Patent Publication Number: US-2022233370-A1

Title: Motor vehicle for a person with reduced mobility, which is easier to get into/out of

Description:
The present invention relates to the technical field of vehicles for persons with reduced mobility and whose physical capacity does not allow the driving of a traditional vehicle without transformation of the latter, and relates in particular to a motor vehicle allowing an extremely easy and safe way to get into and out of. 
     A motor tricycle, proposed by the inventors of the present invention, is known from French patent application FR 3 005 931, allowing such a person to recover a lost autonomy while having the pleasure of driving in a vehicle whose design is modern. 
     Briefly, the chassis frame of this motor tricycle has a platform on which can be carried a person in a wheelchair, or which can be equipped with a specific chair with armrests fixed to the chassis frame, and two steerable wheels located at the front and a driving wheel at the rear, aligned with the longitudinal axis of the tricycle. The tricycle has a side access on each side of the platform, through a side door mounted to pivot about a horizontal axis at the platform. In the closed position, the side door is raised and closes off the tricycle&#39;s interior laterally, and in the open position, the side door is lowered and forms an inclined ramp whose free edge can rest directly on a sidewalk. 
     The main advantages of this tricycle, due to the lateral access it offers, are that it allows the driver to park in a motor vehicle space and to get off directly onto the sidewalk, and not on the roadway with the risks and inconveniences that this entails, as well as to allow for a space behind the driving position, leaving one or even two places, according to the motorization power, to accommodate one or two passengers. It therefore allows to travel over long distances with an unequalled level of comfort. 
     The tricycle according to the French patent application FR 3 005 931 is therefore a satisfactory solution in principle. 
     However, in practice, getting on/off the tricycle can in some cases be difficult or even impossible, for example for people who do not have enough strength to climb the ramp, or when the slope of the ramp is too steep, for example when there is no sidewalk. To try to overcome this disadvantage, a hydraulic system has been provided to temporarily lower the entire tricycle. However, such a lowering, besides resulting in a compression of the shock absorbers when the tricycle is in the lowered position, which is not admissible in the long term for the shock absorbers and the wheel tires, prevents fixing motorization elements, etc., under the chassis frame, and thus leads to a more complex arrangement of the tricycle, as it is very different from motor tricycles not intended for people with reduced mobility. 
     It has been proposed to connect the ramp to a movable portion of a vehicle platform. For example, in US application No. 2016/0242975 A1 request, the ramp is connected to a movable portion that can pivot up and down. In U.S. Pat. No. 4,804,308, the ramp is connected to a movable portion of the platform that is vertically movable between high and low positions, with the ramp beginning its downward pivoting movement when the movable portion has begun to approach its low position and beginning its upward pivoting movement at the beginning of the raising of the movable portion to the high position. In both of these examples, only the movable portion of the platform accommodates the person in the wheelchair during the vertical movement between the high and low positions, and getting on and off this movable portion is still via an inclined ramp. Thus, the problems presented above are not solved. 
     The present inventors have sought to solve these problems and to provide a motor tricycle of simple structure and allowing easy access when getting on and off in all cases. 
     The solution according to the present invention is based on the use, for getting on/off, of a vertically movable portion forming part of the platform in the driving position, to which movable portion is connected a folding side that can be placed in a horizontal position in which it is movable in one piece with said movable portion, as will be explained in more detail hereinafter. 
     The present inventors have realized that this solution is not limited to motor tricycles, but can also be applied to any motor vehicle, such as cars. 
     The present invention thus relates to a motor vehicle, comprising:
         a chassis frame,   a steerable front wheel assembly and a rear wheel assembly,   a platform for accommodating at least the driver of the vehicle, at least a portion of the platform being secured to the chassis frame, and   at least one folding side located on one side of the platform and connected thereto so as to be able to pivot between a so-called raised position, in which the folding side has been raised and is generally vertical, and a so-called lowered position, in which the folding side has been pivoted downwards to form a means of access by which a person can get onto the platform and get off the same,
 
the vehicle being characterized in that the platform comprises a stationary portion secured to the chassis frame and at least one lateral movable portion located at one side of the platform, the movable portion being vertically movable relative to the stationary portion in such a way as to be able to be placed in a first position, called the high position, in which it is flush with the stationary portion, and a second position, called the low position, in which it is located at a lower height than that of the stationary portion, means being provided for controlling the vertical movement of the at least one movable portion, the or each folding side being connected to a respective movable portion in such a way that the folding side and the respective movable portion are vertically movable in one piece between the high and low positions while the folding side is in the lowered position.
       

     Thus, when a folding side has been placed in the lowered position, the folding side and the respective movable portion to which it is connected constitute a movable sub-platform which on the one hand is of sufficient size for a person in a wheelchair to be able to be placed on it and on the other hand is vertically movable while remaining generally horizontal. In other words, the folding side and the respective movable portion are vertically movable in one piece from the high position to the low position, and vice versa, with the folding side in the lowered position throughout the entire vertical movement of the movable portion. 
     It is easily understood that when the person wishes to get off the vehicle, he or she simply pivots the folding side to the lowered position, moves onto the sub-platform thus formed, and then lowers the sub-platform to the desired height, such as that of a sidewalk or directly onto the roadway. When the person wants to get on the vehicle, he/she only has to proceed with the same method, except that this time the sub-platform is raised to the high position, from which the person can raise the folding side. 
     It can therefore be seen that the means of access is generally horizontal when getting on/off, which allows an easy access even for people who do not have enough strength to climb a ramp, which by definition is inclined, as in the prior art. 
     Moreover, this result is achieved without increasing the length of the side door in the case where the folding side constitutes a side door of the vehicle, and thus a reduced lateral overall dimension is maintained even when getting on/off, which is particularly important to allow getting on/off when space is limited at the side of the vehicle, as for example in parking lots. 
     Finally, according to the solution of the present invention, the shock absorbers are no longer stressed when getting on/off and the height of the chassis frame is not modified, which allows to keep a conventional positioning for the elements of motorization, drivetrain, etc., making the design of this aspect of the vehicle and its manufacture much simpler. 
     Consequently, the vehicle according to the present invention retains the advantages provided by that of the French patent application FR 3 005 931 while solving the problems it posed. 
     It is advantageous to provide, at a free edge of the or each folding side, a lip, preferably foldable, which, in the lowered position of the folding side, preferably at least when approaching the lowered position of the movable portion, is inclined relative to the rest of the folding side so as to facilitate getting onto said folding side and getting off the same by preventing said free edge of the folding side, which would otherwise form a small step, of the thickness of the folding side, from constituting an obstacle to the wheels of the wheelchair. 
     It is underlined here that the term “folding side” is understood to mean any element of the panel or plate type capable, in the lowered position, of forming a means of access to the platform. 
     Preferably, the vehicle further comprises stabilizing means for stabilizing the vehicle during the movement of the at least one movable portion between the high and low positions. This further increases the safety of the person with reduced mobility. 
     By “stabilizing means” is meant dedicated means allowing the vehicle to be kept immobile when getting on/off, in addition to the conventional means such as handbrakes which are used to immobilize the vehicle. 
     An example of stabilizing means is stabilizing jacks designed to raise the vehicle above the ground, well known for example in motor homes and truck cranes. The number of such stabilizing jacks and their position can be determined in particular by the weight and dimensions of the vehicle, and two stabilizing jacks, one in the front region of the vehicle and the other in the rear region, could be provided under each side of the platform. 
     Preferably, the stabilizing means will be formed by the at least one stand forming part of the means for controlling the vertical movement of the at least one movable portion according to one embodiment that will be discussed below. 
     Preferably, the at least one movable portion forms part, in the high position, of the section of the platform where the driving position of the vehicle is located. This will be preferred, for example, when the vehicle is a tricycle. Thus, the vehicle may be a tricycle, including a tricycle in which the steerable front wheel assembly comprises a single front wheel and the rear wheel assembly includes two rear wheels, or a tricycle in which the steerable front wheel assembly includes two front wheels and the rear wheel assembly includes a single rear wheel or two twin rear wheels. 
     The at least one movable portion may also form part, in the high position, of a section of the platform intended to accommodate a passenger of the vehicle, the vehicle comprising two front wheels and at least two rear wheels. 
     Preferably, the vehicle comprises two folding sides, located on either side of the platform, and two movable portions. Thus, it is possible to get on/off the vehicle from both sides of the vehicle, as required. 
     The at least one folding side may constitute, in the raised position, a side door of the vehicle. 
     Alternatively, the vehicle may further comprise at least two side doors, located on either side of the platform and capable of being opened and closed, the or each folding side extending, in the raised position, opposite a respective side door, on the interior side of the vehicle, the or each folding side being capable of being moved to the lowered position after opening the respective side door. The solution according to the present invention is therefore fully applicable to conventional vehicles, where only the design of the chassis frame needs to be modified for the integration of the at least one movable portion of the platform. 
     The vehicle may further comprise, for the or each folding side, a non-manual actuator able to move the respective folding side between the raised position and the lowered position. This actuator may take any suitable form, such as electric or hydraulic jacks, etc. 
     Alternatively, the or each folding side may be connected in a freely pivotable manner to the respective movable portion of the platform, there being further provided, for the or each folding side, manual raising means for raising the folding side from the lowered position to the raised position, as well as stopping means for stopping the folding side in the lowered position and locking means for locking the folding side in the raised position. 
     The raising means may comprise, for the or each folding side, a horizontal handrail mounted so as to be pivotable about a vertical axis located in front of or behind the respective movable portion of the platform, the handrail being further connected to an edge of the folding side by a belt or strap. Such raising means are particularly dependable and simple to implement, as the handrail can also be used by the person to move around on the folding side/moving portion when getting on/off. 
     Preferably, the chassis frame is configured such that the at least one movable portion is, in the high position, inscribed in and protected by the chassis frame. 
     In other words, for the or each movable portion, the structural elements of the chassis frame define sides of an opening forming a space in which the movable portion is placed in the high position, these structural elements thus protecting said movable portion. 
     Particularly in the case where the vehicle is a tricycle, the chassis frame may comprise a central portion and, on each side thereof, a front lateral extension and a rear lateral extension, the chassis frame thus being H-shaped, a space being formed between the front and rear lateral extensions located on the same side of the central portion, in which space a respective movable portion of the platform is placed when in the high position. 
     With this configuration of the chassis frame, the movable portions of the platform form a section of the surface of the platform upon which the person is when in the driving position, thus not increasing the lateral dimensions of the vehicle, and the movable portions are furthermore inscribed in the chassis frame and protected by it when the vehicle is being driven. 
     For the or each movable portion, locking means for locking the movable portion in the high position may be provided, such as means with locking fingers which, in a so-called locking position, oppose a movement of the movable portion and in a so-called release position, no longer oppose such a movement. 
     Preferably, the means for controlling the vertical movement of the at least one movable portion are able to ensure a continuous vertical movement of the at least one movable portion and to stop this vertical movement at any height lower than that of the movable portion in the high position. In this way, the user can define the low position of the movable portion depending on the needs, as for example depending on the height of the sidewalk or to go directly onto the road. 
     The means for controlling the vertical movement of the at least one movable portion may be manual. A manual crank system could thus be provided, which would be turned by the user, and which would make the movable portion go up and down, for example via a wheel and worm screw system, with the interposition of a force multiplier. 
     Preferably, the means for controlling the vertical movement of the at least one movable portion comprises, for the or each movable portion, at least one non-manual actuator. 
     In one exemplary embodiment, the or each actuator is a linear actuator, in particular a jack, a first part of which, called fixed, is secured to the chassis frame and a second part of which, called movable, is connected to the respective movable portion of the platform. The vehicle may advantageously comprise, on each side of the fixed portion of the platform where a movable portion is located, at least one tubular structure secured to the chassis frame and comprising an upright carrying a support to which the fixed part of a respective linear actuator is connected. A single actuator may be provided for each movable portion. In this case, it will be advantageous to provide on the side opposite to the one where the actuator is located, a translation guide, such as a ball bearing slide for example, to ensure that the movable portion and the folding side remain globally horizontal when getting on/off. Preferably, on each side of the fixed portion of the platform where a movable portion is located, a front tubular structure and a rear tubular structure are provided, to each of which the fixed part of a linear actuator is connected, so that the movement of each movable portion of the platform is controlled by two linear actuators. The linear actuator(s) may, for example, be hydraulic jacks, electric jacks, etc., or consist of a rack-and-pinion mechanism whose rack is secured to the movable portion and extends upwardly therefrom. In the case of such linear actuators, the vehicle stabilizing means may be stabilizing jacks, as mentioned above. 
     However, according to one preferred embodiment, the means for controlling the vertical movement of the at least one movable portion comprises, for the or each movable portion:
         an actuator formed by a stand foldable under said movable portion and able to be unfolded downwards from the latter, the stand being motorized by motorization means, the stand constituting said stabilizing means; and   means for guiding said movable portion in translation with respect to the chassis frame.       

     When the stand is in contact with the ground, its folding allows the movable portion to be lowered while its unfolding allows it to be raised. The motorization means will preferably ensure a continuous movement of the stand, in both directions, allowing to stop the movable portion at any height, as mentioned above. 
     In addition to the function of raising/lowering the movable portion/folding panel, the stand ensures a stabilization function of the whole vehicle throughout the raising/lowering, which is particularly important from the point of view of safety of the person with reduced mobility. 
     Preferably, the stand comprises a main arm and a secondary arm, the main arm having a first end articulated to a part located inside a hollow longitudinal member belonging to the movable portion, and a second end capable of coming to bear on the ground after the stand has been unfolded, the secondary arm being foldable inside the main arm and having a first end articulated to the latter and a second end articulated to a bearing fixed inside said longitudinal member, and the motorization means comprises said part and means for driving said part in translation in the two direction of translation. 
     It is readily understood that since the end of the secondary arm which is articulated to the bearing is fixed in translation, a translational movement of said part, and thus of the end of the main arm which is articulated thereto, away from said bearing causes the main arm and the secondary arm to fold back towards said longitudinal member, whereas a movement towards said bearing causes the main arm and the secondary arm to unfold. 
     Preferably, the part is a sleeve and the means for driving said part in translation comprises a shaft extending through said sleeve and along the inside of said longitudinal member, and means for rotating the shaft that are able to rotate the shaft in both directions of rotation, the sleeve and the shaft being connected by a helical connection such that a rotation of the shaft causes a translation of the sleeve. For example, the shaft may be a ball splined shaft and the sleeve may be a ball cage sleeve, in which case the means for driving in translation is implemented as a ball screw, or the shaft may be externally threaded and the sleeve internally threaded, in which case the means for driving in translation is implemented as a screw-nut system. 
     The second end of the main arm may be provided with a caster. Thus, when the movable portion is in a low position, i.e., when a person is getting on or off, it is possible to roll the vehicle over a small distance in order not to leave it in a dangerous position, for example. Together with this ability to move, this caster allows for a slight height misalignment between, on the one hand, the point of contact with the ground and, on the other hand, the axes of articulation of the main and secondary arms inside said hollow longitudinal member, which allows to reduce the power that must be provided by the motorization means at the beginning of the raising, and thus to relieve the latter. 
     In a preferred variation, the second end of the main arm is provided with an articulated plate, preferably articulated about a first pivot axis that is horizontal and parallel to the longitudinal axis of the main arm, and a second pivot axis that is horizontal and perpendicular to the first pivot axis, one of the first and second pivot axes being located above the other. Such an articulation, and particularly with the preferred configuration indicated above, allows the plate to be properly placed on an inclined ground for a proper stabilization by the stand. Moreover, the use of such a plate allows to offer a larger contact surface with the ground, compared to the use of a simple castor, and thus to avoid that the stand sinks into the ground, for example in case of muddy ground. The plate thus allows the stand to ensure its stabilization function in all cases. 
     Preferably, the means for guiding in translation consist of, for the or each movable portion, two sliding connections, each at a lateral edge of said movable portion and each comprising a fixed guiding part secured to the chassis frame and a sliding guiding part secured to said movable portion. 
     In the case where the vehicle is a tricycle, it may advantageously comprise, on each side of the central portion of the platform, at least one tubular structure secured to the chassis frame and comprising an upright to which, where appropriate, the fixed guide part of a sliding connection is fixed. The tubular structure(s) may also serve as a support for accessories, such as, for example, reflectors, lamps, wheelchair immobilization clamps, at the front and rear, etc. 
     In the case where the vehicle is a tricycle, it may advantageously comprise, behind the driving position of the vehicle, at the rear of the platform, a seat support which is foldable and/or removable so as to be able to be placed in a first position, so-called position of use, in which it supports a single or double seat, or a second position in which it has been folded down or, if applicable, removed, in order to free the section of the platform located behind the driving position, so as to allow a person in a wheelchair to position themselves behind said driving position. Advantageously, a removable and/or collapsible front seat may also be provided in the driving position for use when the wheelchair is behind the driving position. 
     The features of the present invention described above are not limited to the specific type of motorization used for the vehicle. However, it will be readily understood that it is important that such motorization allows for travel in reverse. Indeed, since the vehicle according to the present invention allows a person with reduced mobility to get on and off the vehicle very easily, particularly onto a sidewalk, to fully benefit from the advantages provided by the present invention the driver must be able to perform maneuvers such as parallel parking, herringbone parking, etc., which require travel in reverse. 
     In the context of incorporating such a reverse gear into a vehicle according to the present invention which would be a tricycle, the present inventors have developed an innovative reverse gear system which can be used in the case where the rear wheel assembly of the vehicle is a single rear wheel or two twin rear wheels. 
     Thus, preferably, the vehicle according to the present invention includes a reverse gear system able to drive in reverse rotation the wheel axle of the rear wheel assembly, the reverse gear system comprising:
         a dedicated motor means, comprising a driving shaft intended, in use, to rotate in a direction of rotation leading to a reverse movement of the vehicle, parallel to the wheel axle;   selective coupling means controllable so as to couple or uncouple the driving shaft and the wheel axle; and   means for controlling the selective coupling means.       

     Preferably, the selective coupling means is a clutch, so-called reverse clutch, a first part of which is fixed in rotation, directly or indirectly, to the driving shaft and a second part of which is fixed in rotation, directly or indirectly, to the wheel axle. 
     Preferably, the dedicated motor means is an angle drive electric motor, which allows the motor means to be arranged so that its longitudinal direction is parallel to that of the vehicle, in this way the reverse gear system is compact and fits easily behind the vehicle bodywork, without protruding laterally from the latter. 
     The means for controlling the selective coupling means, in particular the reverse clutch, may be formed by any suitable means, which are well known per se, and these means may be, for example, mechanical, hydraulic or electrical. 
     Advantageously, the reverse clutch may be an electromagnetic clutch, for example with teeth. 
     The reverse clutch could be interposed directly between the driving shaft and the wheel axle, without interposing complementary elements such as a drivetrain. 
     However, in a preferred embodiment, the vehicle comprises a forward drive system comprising a motor means for forward drive, located forward of the rear wheel assembly and having a driving shaft connected by a belt to a drivetrain which comprises a drive shaft rotated by the belt and driving the wheel axle in forward drive rotation, the drive shaft extending outwardly so that an end section thereof lies beyond said belt, the selective coupling means, if applicable the second part of the reverse clutch, being connected to said end section of the drive shaft. 
     The present inventors have realized that the reverse gear system as defined above is not limited to use on a vehicle according to the present invention, i.e., incorporating a movable portion and a folding side for getting a person with reduced mobility on/off, but that it could also be used for conventional two or three-wheeled vehicles of scooter type. 
     Indeed, conventionally, two or three-wheeled vehicles like scooters are not equipped with a reverse gear system and it is up to the user, by his or her own strength, to move the vehicle backwards while controlling it, which in practice is at best delicate for people of good stature, but very difficult for most people. In any case, moving the vehicle backwards is tedious. 
     The reverse gear system solves this problem, as the user only has to steer the vehicle, and no longer has to move it by their own force. 
     Thus, there is disclosed herein a reverse gear system for a scooter-type motor vehicle having a single rear wheel assembly, which may consist of, for example, a single rear wheel or two twin rear wheels, the reverse gear system being able to drive the wheel axle of the rear wheel assembly in reverse rotation, the reverse gear system being characterized in that it comprises:
         a dedicated motor means, comprising a driving shaft;   selective coupling means controllable so as to couple or uncouple the driving shaft and the wheel axle; and   means for controlling the selective coupling means.       

     The optional features of the reverse gear system described in connection with the vehicle according to the present invention are also optional features of the reverse gear system as defined in the preceding paragraph. 
     By “dedicated motor means” is meant that the motor means providing reverse travel is separate from that providing forward travel. 
    
    
     
       To better illustrate the object of the present invention, particular embodiments thereof will be described hereinafter, with reference to the appended drawings. 
       In these drawings: 
         FIG. 1 : perspective view of a motor vehicle according to a particular embodiment of the present invention, here a tricycle, in the configuration with the folding side in the lowered position, the movable portion in the high position and the stand unfolded on the right of the view, and in the driving position on the left of the view; 
         FIG. 2 : top perspective view of the chassis frame of the vehicle of  FIG. 1 , with the presence of a folding side; 
         FIG. 3 : bottom perspective view of the chassis frame of  FIG. 2 ; 
         FIG. 4 : detailed view, from below, of the stand in the unfolded position; 
         FIG. 5 : detailed view of the connection between a folding side and the respective movable portion, with the folding side in the raised position; 
         FIG. 6 : detailed view similar to  FIG. 5 , with the folding side in the lowered position; 
         FIG. 7 : detailed view of the folding side in the raised position, showing the means for locking it in the raised position; 
         FIG. 8 : perspective view of the vehicle in driving configuration, i.e., with the folding side in the raised position, the movable portion in the high position and the stand in the folded position; 
         FIG. 9 : perspective view of the vehicle in the configuration with the folding side in the lowered position, the movable portion in the high position and the stand in the unfolded position; 
         FIG. 10 : perspective view of the vehicle in the configuration with the folding side in the lowered position, the movable portion in the low position and the stand completely folded; 
         FIG. 11 : schematic top view of a tricycle type vehicle, with two steerable front wheels and one rear wheel, and a single seat behind the driving position; 
         FIG. 12 : view similar to  FIG. 11 , but with two seats at the rear; 
         FIG. 13 : view similar to  FIG. 11 , but with a seat in the front and a wheelchair at the rear; 
         FIG. 14 : view similar to  FIG. 11 , but for a tricycle type vehicle with one front steerable wheel and two rear wheels; 
         FIG. 15 : view similar to  FIG. 14 , but with two seats at the rear; 
         FIG. 16 : view similar to  FIG. 14 , but with a seat at the front and a wheelchair at the rear; 
         FIG. 17 : schematic top view of a four-wheeled vehicle, with a movable portion forming part of the driving position; 
         FIG. 18 : similar view to  FIG. 17 , but with a movable portion forming part of a passenger section; 
         FIG. 19 : side view of the rear wheel and the reverse gear system of the vehicle; and 
         FIG. 20 : partial longitudinal sectional view of the reverse gear system of  FIG. 19 . 
     
    
    
     Referring first to  FIG. 1 , it can be seen therein, represented in perspective view, a motor tricycle  1  according to a particular embodiment of the present invention, which has been illustrated without bodywork. 
     The motor tricycle  1  comprises, in a similar manner to the motor tricycle of the French application FR 3 005 931, a chassis frame  2 , two front steerable wheels  3 , a rear wheel  4 , a platform  5  for accommodating the driver and, if desired, one or two passengers behind the driver, and two side doors  6 . 
     Referring now to  FIG. 2 , it can be seen that the chassis frame  2  is generally H-shaped, and thus comprises a central portion  20  and, on either side thereof, a front lateral extension  21  and a rear lateral extension  22  at a distance from each other. The central portion  20  has a general form of a rectangular frame comprising two side rails  200  ( FIG. 3 ), the ends of which are connected at the front by a crossmember  201  and at the rear by a crossmember  202 . Each lateral extension  21  and  22  is formed by two beams,  210  and  220  respectively, which extend outwardly from a respective side rail  200 , approaching each other as they extend away from the side rail  200 , so that the free ends of the beams  210 ,  220  are close to each other. On each side of the central portion  20  is thus formed a space  23  ( FIG. 10 ) delimited by the side rail  200  and the two beams  210 ,  220 . 
     Referring to  FIG. 1 , it can be seen that the platform is supported by the chassis frame  2  and comprises in particular a central, stationary portion  50  and two vertically movable lateral portions  51 . 
     The stationary portion  50  corresponds to the central portion  20  and to the lateral extensions  20 ,  21  of the chassis frame  2 , on which have been attached plates for closing the openings that the chassis frame  2  has. 
     Referring also to  FIG. 2 , it can be seen that each movable portion  51  comprises a rigid frame  510  across which a closing plate  514  extends ( FIG. 1 ). 
     The frame  510  is dimensioned such that at least a portion of the frame  510  extends into the space  23  when the movable portion  51  is in the high position. 
     Here, the frame  510  is formed by an inner longitudinal member  510   a , an outer longitudinal member  510   b , and two crossmembers  510   c  connecting them at their ends. In the high position, the inner longitudinal member  510   a  is located in the vicinity of the side rail  200  of the chassis frame  2  while each crossmember  510   c  is located in the vicinity of a respective beam  210 ,  220 . The inner longitudinal member  510   a  thus has a length at least slightly less than the length of the space  23 . The outer longitudinal member  510   b , on the other hand, has a length greater than the length of the space  23 , and to this end the crossmembers  510   c  extend beyond the beams  210 ,  220 , so that the outer longitudinal member  510   b  is located outside the space  23 . In particular, each end of the outer longitudinal member  510   b  is located, when the movable portion  51  is in the high position, opposite the free ends of the beams  210 ,  220  forming one of the lateral extensions  21 ,  22 . 
     Referring further to  FIG. 3 , it can be seen that the outer longitudinal member  510   b  has a cross-sectional profile that is generally U-shaped, with its opening directed downward, to receive means  7  for controlling the movement of the movable portion  51  between the high and low positions, and which will now be described in more detail. 
     As can be better seen in  FIG. 4 , the means  7  consist here, in a general way, of a stand  70  foldable into the outer longitudinal member  510   b  and of motorization means  71  for unfolding/folding the stand  70 . 
     The stand  70  comprises a main arm  700  and a secondary arm  701 . One end of the main arm  700  is intended to come to bear on the ground, and is provided with a plate  702 , while the other end terminates as a clevis that is located inside the outer longitudinal member  510   b  and across which is mounted, in an articulated manner, a part  710 . The secondary arm  701  has one end articulated to the main arm  700 , generally midway along the latter, and has its other end articulated to a bearing  711  secured to the inside of the outer longitudinal member  510   b . The main arm  700  has a U-shaped profile, and the secondary arm  701  is sized to be able to be lodged within the main arm  700  when the stand  70  is in the folded position. 
     The motorization means  71  are based on a helical connection type drive, here implemented by a ball screw comprising a ball splined shaft  712 , extending through the part  710  which is here a sleeve, and a means for driving the splined shaft  712  in rotation. 
     The splined shaft  712  extends inside the outer longitudinal member  510   b  and is supported, at a first end, by the bearing  711 , and at a second end by a bearing  714  mounted fixedly in the outer longitudinal member  510   b , at which the splined shaft  712  is coupled to a drive shaft  715  also extending along the outer longitudinal member  510   b  and projecting out of the rear end thereof, at one end of which it is coupled to a motor  716  ( FIG. 6 ), for example an electric motor, configured to be able to rotate the drive shaft  715 , and thus the splined shaft  712 , in both directions of rotation. The motor  716  is remotely controllable. 
     Due to the helical connection between the stand  70  and the splined shaft  712 , a rotation of the latter in a first direction of rotation will result in a translational movement of the sleeve  710  in the direction away from the bearing  711 , and thus in a folding of the stand  70  towards the inside of the outer longitudinal member  510   b , whereas a rotation of the splined shaft  712  in a second direction of rotation, opposite to the first one, will result in the sleeve  710  being brought closer to the bearing  711 , and thus in an unfolding of the stand  70 . 
     As will be described below, the folding and unfolding of the stand  70  allows, depending on the position of the movable portion  51 , to move the latter vertically between a high position, in which the movable portion  51  is at the level of the stationary portion  50  of the platform  5 , and a low position, in which the movable portion  51  is at a lower height than that of the stationary portion  50 . 
     Locking means for locking each movable portion  51  in position are further provided to immobilize the movable portion  51  in any of the low and high positions and in any position between them. These locking means may in particular be integrated within the motor  716 , and consist, for example, of a power failure brake in the case of an electric motor  716 : in the absence of control of the locking means, thus in cases where it is not desired to move the movable portion  51 , the brake automatically prevents the movable portion  51  from moving, and this without consuming energy. 
     The movement of each movable portion  51  relative to the chassis frame  2  is guided by the translation guiding means  8 , which generally consist here of two sliding connections between the movable portion  51  and the chassis frame  2 . 
     In the embodiment represented, as can be seen in  FIGS. 5 and 10 , each sliding connection, one at each end of the outer longitudinal member  510   b , comprises a rod  81  that is secured to the outer longitudinal member  510   b  and extends vertically, upwards, from the latter, and at least one plain bearing, here two plain bearings, mounted in a cylindrical tube  82  extending vertically, upwards, from the free ends of the beams  210 ,  220  forming a lateral extension  21 ,  22 , to which it is fixed by a bracket  83  the horizontal wing of which is fixed to said beams  210 ,  220 , and the vertical wing of which is fixed to the tube  82 . Each rod  81  is fixed, at its lower end, by any appropriate means, to one of the free ends of the outer longitudinal member  510   b , which as indicated above is located opposite the free ends of the beams  210 ,  220 , and extends in a sliding manner in the tube  82 , passing through the plain bearing or bearings. 
     The lateral portion  51  is thus guided in vertical translation at each of the two free ends of the outer longitudinal member  510   b.    
     It is emphasized here that each tube  82  is also fixed to the chassis frame  2  at the upper end of the tube  82 , in particular fixed if applicable to a front tubular structure or a rear tubular structure  25  secured to the chassis frame  2  and provided respectively in front of the front lateral extensions  21  or behind the rear lateral extensions  22  ( FIGS. 1 and 2 ). 
     The tubular structures  24 ,  25  can be used as guardrails and as a support for the attachment of accessories, for example safety accessories such as reflectors, safety lamps, etc., or as represented, arms carrying clamps  713  intended to be clamped onto the tubes of the wheelchair frame so as to immobilize the latter on the platform. 
     In addition, safety means  52  are also provided, for the automatic locking of the movable portion  51  when it reaches the high position as well as for its manual unlocking. As can be seen in  FIG. 2 , for example, these safety means  52  may comprise, for each movable portion  51 , two handles  520 , each carried by a support  521  secured to a tube  82 , each handle  520  having a locking finger which, in a so-called locking position, extends through a corresponding hole in said tube  82  and the free end of which is received, in the locking position, in a recess provided for this purpose in the respective rod  81 . The handles  520  are spring biased towards the locking position. When it is desired to move the movable portion  51  downwards, the stand  70  is first unfolded to the ground, then both handles  520  are pulled to disengage the locking fingers from the rod  81  and the tube  82 , so as to allow the rod  81  to slide in the tube  82 , and then the handles  520  are rotated, for example, by at least a quarter turn, into a position where the locking fingers are held disengaged. Prior to raising, each handle  520  will be rotated in the opposite direction, for example at least a quarter turn, such that the locking finger extends through the corresponding tube  82  and will automatically engage the recess in the rod  81  upon reaching the high position. 
     The manner in which the folding sides  6  are connected to the movable portion  51  will now be described with reference to  FIGS. 5 and 6 . 
     First of all, each folding side  6  is here formed by two bars  60  across which is placed a closing means  61  such as, for example, based on sheet metal. 
     Each folding side  6  is connected to a respective movable portion  51  so as to be pivotable between a raised position (left folding side in  FIG. 1 ), in which it extends substantially vertically, and a lowered position, in which it extends horizontally or is slightly inclined towards the interior of the motor tricycle  1  (right folding side in  FIG. 1 ). It may be emphasized here that in this embodiment each folding side  6  constitutes the side door of the vehicle  1  in the raised position. 
     In the embodiment represented, this connection between the folding side  6  and the movable portion  51  is provided at each section of the outer longitudinal member  510   b  that is located in the vicinity of the end of the space  23 . A fastening tab  511  and a U-shaped fastening piece  512 , used for fastening the rod  81 , are carried by the outer longitudinal member  510   b , on top of the latter, and one end of a bar  60  extends between them. Each of the fastening tabs  511 , the fastening piece  512 , and the end of the bar  60  has a hole therethrough, with the holes aligned and a pivot  513  extending fixedly therethrough. The holes in the ends of the two bars  60  are sized to allow pivotal movement of the bars  60 , and thus of the folding side  6 , about the pivot axis formed by the two pivots  513 . In addition, said ends of the bars  60  each has an angled step  601  complementary in shape to that of the outer beam  510   b , in particular forming a stop face  602 . Two stops  603  are attached to the outer vertical face of the outer longitudinal member  510   b.    
     The various elements above are sized and arranged so that in the lowered position, each stop face  602  abuts the respective stop  603  and each bar  60  also bears against the upper face of the outer longitudinal member  510   b , so as to safely stop the downward pivoting of the folding side  6  in the lowered position. 
     The folding sides  6  are held in the raised position by push-lock means  64 , which can be better seen in  FIG. 7 . Each tube  82  carries a lug  640  extending towards the folding side  6 , and this folding side  6  has a hole  641  on each of its two side edges, which are vertical in the raised position, in which the end of the lug  640  engages, thus immobilizing the folding side  6 . Simply pushing on the folding side  6  disengages the lug  640  from the hole  641  or engages it in the hole  641 . 
     The folding sides  6  can be raised from the lowered position to the raised position by manual means  9  formed here by a handrail  90  mounted on the rear side of the tube  82  so as to be pivotable about the axis of the tube  82 , and by an inextensible connecting means between the handrail  90  and an edge of the folding side  6 , for example a side or outer edge, as for example by a strap or a belt (not represented). 
     The manner in which the driver can get on or off the vehicle  1  will now be described with reference to  FIG. 1  and  FIGS. 8 to 10 . 
     In the driving configuration of the vehicle  1  ( FIG. 8 ), the movable portions  51  are in the high position, the folding sides  6  are in the raised position, the stands  70  are in the folded position and the safety means  52  are in the locking position. The driver, and possibly one or two passengers behind him, is located on the platform  5  composed of the stationary portion  50  and the two movable portions  51  which are in the same plane. The folding sides  6  constitute the doors that close the passenger compartment laterally. 
     After stopping the vehicle  1 , the driver wishing to get down on one side will move the appropriate folding side  6  from the raised position to the lowered position, the respective movable portion  51  remaining in the high position. This is done simply by disengaging the push-lock means  64 , with the folding side  6  pivoting downwards due to its weight and the driver controlling the opening of the folding side  6  by accompanying the pivoting of the handrail  90  caused by that of the folding side  6 . 
     The driver then controls the unfolding of the stand  70 , by controlling the motor means  716 , until the plate  702  comes into contact with the ground, and only then does he disengage the safety means  52  by pulling on the handles  520  and then rotating them. The stand  70  allows to stabilize the movable portion  51 /folding side  6 . 
     It is emphasized here that the unfolding can be continued even after contact with the ground, in order to correct the attitude of the vehicle  1  in case for example the road is inclined. The continued unfolding of the stand  70  will lead the front or rear part of the vehicle  1  to rise correspondingly until its attitude is horizontal, this movement being allowed by the shock absorbers of the vehicle  1 . 
       FIG. 9  shows the motor tricycle  1  in the configuration with the folding side  6  in the lowered position, the movable portion  51  in the high position and the stand  70  in the unfolded position. 
     The driver can then position himself on the movable sub-platform formed by the folding side  6  and the movable portion  51 . The fact that the folding side  6  is horizontal or slightly tilted upwards allows, in case the driver is in a wheelchair, to avoid the wheelchair rolling involuntarily outwards. 
     The driver then controls the motor  716  to fold up the stand  70 , and because the safety means  52  have been disengaged, the movable sub-platform will descend vertically, while remaining horizontal. 
     This descent is stopped by the driver, simply by stopping the motor control  716 , at the desired height, for example at the height of a sidewalk on which the outer edge of the folding side  6  will have come to bear. The driver then simply goes off the movable sub-platform. 
     The movable sub-platform can be lowered until the stand  70  is fully folded into the outer longitudinal member  510   b , as represented in  FIG. 10 . This allows the movable sub-platform to be lowered to the roadway, in the event that the driver does not goes off to a sidewalk. 
     Once the driver has left the movable sub-platform, the driver rotates the handles  520  for locking fingers, and can operate the motor  716  to unfold the stand  70 , which will cause the movable sub-platform to rise, until the movable part  51  is in the high position and locked by the safety means  52 . The stand  70  can then be folded back into the outer longitudinal member  510   b  and the driver can raise the folding side  6  by pushing on the handrail  90  after moving to one side, and then pressing against the folding side  6  to engage the push-lock means  64 . 
     It will be easily understood that when the driver wishes to get back into the vehicle  1 , after having placed himself on the side of the place where the movable sub-platform will come to be placed on the ground, it is enough for the driver first to unlock the folding side  6  by disengaging it from the locking means with the push-lock  64 , then to control its opening with the handrail  90 , then to control the unfolding of the stand  70  to the ground, then to disengage the safety means  52 , then to control the folding back of the stand  70  to make the movable sub-platform go down to the desired height, at which point the driver can get on to it. Once on it, the driver rotates the handles  520  so that they are spring-returned to the locking position, the driver then controls the unfolding of the stand  70  to make the movable sub-platform rise to the high position, the movable portion  51  then being automatically locked at its arrival in the high position by the safety means  52 , then the driver folds back the stand  70  in the outer longitudinal member  510   b  and, after the driver has placed himself in the driving position, the driver raises the folding side  6  and engages it in the push-lock means  64 . The vehicle  1  is then again in the driving configuration. 
     It is understood that the particular embodiment just described has been given as an indication and is not limiting, and that modifications may be made without departing from the present invention. 
     For example, a single seat Ss or a double seat Sd can be provided behind the driving position, as illustrated schematically in  FIGS. 11 and 12 , respectively. This seat, whether single or double, will advantageously be foldable so as to allow a wheelchair F to be placed at the rear, as illustrated in  FIG. 13 , in which it can be seen that it is possible to provide a seat Ss at the front, which will advantageously be removable, because it will be connected to the platform, for example, by quick-fixing means, or will be foldable. 
     It is also possible to provide these same configurations on a tricycle having a single front steerable wheel and two rear wheels, as illustrated in  FIGS. 14 to 16 . 
     Alternatively, a platform could be provided that allows two wheelchairs to be positioned one behind the other, one in the driving position and the other at the rear. 
     Furthermore, as previously indicated, the principle of a movable portion and a folding side according to the present invention is not limited to an application to a motor tricycle but is as well applicable to four-wheeled vehicles, as illustrated in  FIGS. 17 and 18 , or more, such as six-wheeled vehicles with four rear wheels. In the case of a vehicle with at least four wheels, it is emphasized that the movable portion can be positioned to be part of, in the high position, the driving position, as illustrated in  FIG. 17 , or be located on the passenger side as illustrated in  FIG. 18 . It is of course also possible to provide more than one movable portion, for example, two movable portions, one on each side, and the movable portion(s) could just as well be placed at the front or at the rear of the vehicle. 
     Above, the features of the vehicle  1  that allow a person with reduced mobility to get on/off have been described. The vehicle  1  is also equipped with a reverse gear system  1000  shown in  FIGS. 19 and 20 . 
     In the embodiment represented, the rear wheel  4  is a drive wheel rotated by a forward drive system similar to that found on two-wheeled vehicles of the scooter type, in which the power supplied by a forward drive means, located in front of the reverse gear, is transmitted, by a belt, to a drivetrain, for example composed of a primary drivetrain and a secondary drivetrain, which is engaged with the wheel axle of the rear wheel  4  so as to rotate it in the forward direction. The belt and drivetrain are conventionally protected by a housing  1001  which can be seen in  FIGS. 19 and 20 . 
     Since the present invention not being limited to any particular forward drive system, and since such systems are well known per se, they will not be described in further detail. It may be emphasized, however, that in the illustrated embodiment, the drivetrain includes a primary drivetrain and a secondary drivetrain, and the drive shaft  1002  ( FIG. 20 ) of the primary drivetrain extends outwardly a distance such that its end region protrudes from the housing  1001 . 
     The reverse gear system  1000  includes a motor  1003  and a clutch  1004  interposed between the motor  1002  and the drive shaft  1001 . 
     The motor  1003  is an electric motor carried by a support  1005  that is itself attached to the housing  1001 . In particular, the motor  1003  is an angle drive motor, well known per se, which allows it to be oriented so that its longitudinal direction is parallel to that of the vehicle  1 , and thus to obtain a more compact arrangement of the reverse gear system  1000 . 
     The output shaft  1006 , or driving shaft, of the motor  1003  is thus parallel to the wheel axle of the rear wheel  4 , as can be seen in  FIG. 20 . 
     The clutch  1004  is here a toothed electromagnetic clutch, a first part  1007  of which is made rotationally secured to the output shaft  1006  by any suitable means, such as by key, and a second part  1008  of which is rotationally secured to the end region of the drive shaft  1001  by any suitable means, such as by key. Since the electromagnetic toothed clutch and its operating principle are well known per se, it is not necessary to describe them in further detail. 
     The motor  1003  and the clutch  1004  are both electrically controlled here, which control may be remote from the driving position of the vehicle  1 , in conjunction with the control of the forward drive system. Preferably, there will be a first button, which controls the turning on/off of the motor  1003 , and a second button which controls the engagement/disengagement of the clutch  1004  and the driving in rotation/stopping of the output shaft  1006  of the motor  1003 . 
     In forward motion, the clutch  1004  is automatically placed in the disengaged position, such that rotation of the drive shaft  1002  is not transmitted to the output shaft  1006  of the motor  1003 . 
     When the driver wishes to shift into reverse, he must first press the first button, to start the motor  1003 . If he then presses the second button, the clutch  1004  is brought to the engaged position and the output shaft  1006  is caused to rotate, this rotation being transmitted to the drive shaft  1002  through the clutch  1004 , and from there to the wheel axle of the rear wheel  4 . When the driver releases the second button, the output shaft  1006  stops rotating and the clutch  1004  is disengaged. Thus, the driver controls the movement of the vehicle in reverse by pressing the second button, and the driver controls the speed by pressing the second button for a longer or shorter time (pulse control). 
     It is emphasized here that during a reverse drive, the forward drive remains available to the driver: the acceleration and braking controls of the forward drive can be used at any time, as the clutch  1004  is disengaged upon release of the second button. This is particularly important because the driver must be able to move the vehicle without delay and, for example, not obstruct traffic. 
     Thus, it can be seen that the driver of the vehicle  1  will be able to perform correctly all the usual maneuvers that a vehicle should be able to perform, such as, for example, parallel parking.