Abstract:
The invention relates to a small vehicle, particularly a wheel chair, comprising a chassis having a monocoque-type main body to which arms for supporting wheels are coupled and at which a seat component can be attached. The main body is designed as a monolith and preferably is manufactured from an extruded profile of aluminium or an aluminium alloy, or is made of wound sheet metal or of plastic. Four arms for two freely pivotable supporting wheels and two driving wheels are springably coupled to said main body.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to a small vehicle, particularly a wheel chair comprising a chassis having a monocoque-type main body.  
           [0002]    Wheel chairs, including those which are driven by a motor, usually comprise a wheel chair frame in which a seat is integrated, two wheels which can be driven and two wheels which can be either freely pivoted or steered by a motor wherein said wheels are directly coupled to said frame. The drivable wheels can be driven manually via hand rims or driven by a motor. Such wheel chairs often comprise a folding mechanism which allows folding of the wheel chair frame in order to reduce the overall size for the purpose of transport of the wheel chair. A wheel chair of this kind is for instance disclosed in EP 0 790 049 A2.  
           [0003]    Wheel chairs of the kind as explained above are rather unsuitable for outdoor operation, that is for operation outside houses and particularly on uneven tracks, for instance tracks in fields or woods. The frame construction as described above has only a relatively low stability. Moreover, direct coupling of the wheels to a pipe frame only allows a suspension which is insufficient for uneven tracks since the only spring system is usually the one provided by the pneumatic tires.  
           [0004]    Wheel chairs having acceptable driving and performance characteristics for outdoor operation are also known. However, the amount of time, work and effort needed for dismantling such wheel chairs for the purpose of transport is not acceptable.  
           [0005]    There is a need for a small vehicle, particularly a wheel chair which has sufficient stability suitable also for outdoor operation as well as a drivability suitable for outdoor operation and, at the same time, can be dismantled so that transport thereof is possible in a typical trunk of an automobile.  
         SUMMARY OF THE INVENTION  
         [0006]    The small vehicle according to the present invention has a chassis having a monocoque-type main body. Four arms for supporting the wheels are springably coupled to the main body and a seat component is mounted at said main body. While according to the prior art discussed above a seat is integrated in a pipe frame and the wheels are directly coupled to said pipe frame, in case of the small vehicle according to the present invention the monocoque-type main body performs the function of supporting the suspension. The main body has sufficient stability to perform this supporting function.  
           [0007]    The main body is designed as a monolith. This means that the main body has a block-like structure which provides sufficient stability, is relatively light weight and has corresponding attachment points for supporting the arms and for receiving the seat component. For this, the main body for example can be manufactured from an extruded profile, i.e. it can be provided in the form of a hard alloy extrusion or extruded shape made of aluminium or an aluminium alloy. Moreover, the main body can be made of a suitable plastic, a compound material, or of wound sheet metal.  
           [0008]    Two freely pivotable wheels and two driving wheels can be detachably mounted at said at said arms, preferably by means of quick release devices. The driving wheels preferably comprise a hub motor, that is a motor which is provided in the region of the wheel hub. Accordingly, there is no necessity of providing a drive train from the vehicle frame to the driving wheels. The torque for driving the vehicle is provided in the hub motor and the stationary portion of the hub motor merely must be supported at the corresponding arm via a suitable support element to enable driving operation.  
           [0009]    Electric motors are particularly suited for driving such small vehicles. Storage batteries necessary for power supply can be mounted at the main body, preferably via suitable quick release devices which allow quick and easy change of the storage batteries. Connection points for the storage batteries can be provided at opposite sides of the main body. Moreover, there can be provided several connecting points for selective operation with one or several storage batteries, wherein, in case the vehicle is to be operated with only one storage battery, this storage battery is mounted in a central position with respect to the center axis of the vehicle, while, if the vehicle is to be operated with several storage batteries, these storage batteries are mounted symmetrically with respect to the center axis of the vehicle.  
           [0010]    The seat component of the small vehicle according to the present invention preferably comprises a seat, a back of seat and foot rests as well as two arm rests and is provided as a complete unit. This unit is adapted to be mounted to the main body and to be dismounted therefrom by means of a quick release device. The seat component can be foldable. Due to the modular structure of the small vehicle the seat can be designed with particular view to ergonomics so that also seat pans for seriously handicapped persons can be used. Moreover, the seat component can be rotatably arranged so that upon turning the seat by 180° a vehicle having rear wheel drive will become a vehicle which has front wheel drive.  
           [0011]    The arms for supporting the freely pivotable wheels are preferably designed as springably supported dual arms. This ensures that the caster of the freely pivotable wheels remains essentially constant over the entire range of spring, particularly in case the freely pivotable wheels are coupled to the arms by means of plug-in axles which extend vertically to the ground. In case there is only a limited travel of the spring system, the front arms also can be designed as mono-arms.  
           [0012]    The arms provided for supporting the driving wheels are preferably designed as longitudinally arranged arms which are supported at the main body via a spring/shock absorber unit.  
           [0013]    A small vehicle designed as a wheel chair as explained above has excellent stability. The wheels may be springably supported to also allow operation on uneven tracks. At the same time, the structure and design of the wheel chair allow it to be dismantled into single components, making it possible to transport the wheel chair in the trunk of a common automobile. After the four wheels are detached from the arms, which for instance, can be done very easily if plug-in axles and quick release devices are used, and after the seat component and, as the case may be, storage batteries are removed, only the main body and the four arms, remain. This module unit has a flat shape which can be easily transported. The wheels and the storage batteries also can be easily stowed away and the seat component can also be brought into a space-saving flat form, if a folding mechanism is used.  
           [0014]    Particularly in cases where electric motors are used as driving units, the main body can have interfaces for electric circuits at the connection points of the driving wheels and/or the seat component and/or the storage batteries. A control panel, including a console, can be provided at an arm rest of the seat component. Furthermore, it is possible to provide wireless signal transmission between the control panel and the driving wheels. If hub motors are provided, a separate control unit may be provided for each hub motor. In that case, it will not be necessary to provide wires for control signals. If the storage batteries are attached to the main body, it will only be necessary to provide power transmission to the hub motors.  
           [0015]    If the storage batteries are also disposed adjacent the wheel hubs of the driving wheels and a wireless signal transmission for control signals is provided, it will not be necessary to provide any wires between the frame and the wheels. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    In the following description, the invention is further explained in connection with a preferred embodiment making reference to the drawing in which  
         [0017]    [0017]FIG. 1 is a perspective representation of a vehicle where the parts are taken apart in exploded view;  
         [0018]    [0018]FIG. 2 is a perspective representation of the vehicle corresponding to FIG. 1 wherein the main components except a control panel are depicted as being assembled;  
         [0019]    [0019]FIG. 3 is a perspective depiction of the wheel chair according to FIGS. 1 and 2 where the seat component is omitted;  
         [0020]    [0020]FIG. 4 is a depiction corresponding to FIG. 3 wherein an additional protective cage is attached;  
         [0021]    [0021]FIG. 5 is a side view of the representation according to FIG. 3;  
         [0022]    [0022]FIG. 6 is a side view of a freely pivotable wheel having a climbing device in a position before a step is contacted; and  
         [0023]    [0023]FIG. 7 is a representation corresponding to FIG. 6 in which a step is negotiated. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0024]    [0024]FIG. 1 shows a wheel chair as an embodiment of the present invention in a so-called exploded view, i.e. with the parts taken apart. The main body  10  is provided in the form of a hard alloy extrusion or extruded shape made of an aluminium alloy  11 . The hard alloy extrusion  11  is closed at both longitudinal ends by corresponding end plates  12  and respective bolts. Internal reinforcing members (not shown) or other components, for instance switching units etc. (not shown) can be provided in the essentially hollow inner space of the main body  10 . On the upper side  13  of the main body  10  there is provided a receiving unit  14  which serves for mounting of a seat component  50  by means of a quick release device which is not shown in detail.  
         [0025]    The seat component  50  comprises frame profiles which together with fabric or upholstery provide a seat  51 , a seat back  52 , a foot rest  53  and a strut  54  for mounting control panel  60 . It is understood that armrests (not shown) can be provided on both sides.  
         [0026]    It is also clear that other structures are possible for the seat component; for instance, a seat and a seat back and, as the case may be, corresponding side parts. The whole seat component  50  can be provided as a monocoque structure and can have corresponding connecting elements for connecting the seat component to the main body or to a corresponding seat frame.  
         [0027]    The seat component is provided with a folding mechanism which allows the seat component  50  to fold when it is detached from the main body  10  so that the seat can be easily transported as one element of substantially flat shape.  
         [0028]    On the left side and on the right side, with reference to the driving direction of the vehicle, two front arms  20  and two rear arms  30 , respectively, are connected to the main body  10 . The rear arms  30  are designed as longitudinal arms which are supported at the main body  10  by means of a spring/shock absorber unit  31 . The front arms  20  are designed as dual arms which are connected to each other by a spring/shock absorber mechanism which is disposed within the main body  10  and which is not shown in the drawings.  
         [0029]    The two driving wheels  35  are coupled to the rear arms  30  via horizontally extending plug-in axles  36  and via quick release devices which are not shown in detail. Two front wheels  25 , which are freely pivotable, are coupled to the front arms  20  via vertically extending plug-in axles  26  and via quick release devices which are also not shown in detail. As can be seen for instance from FIGS.  5  to  7 , the position of the axis of rotation  27  of the front wheel  25  is offset with respect to the position of the plug-in axle  26 . Consequently, a caster is provided so that the front wheels  25  are always oriented towards the driving direction when the vehicle is driving straight ahead. The steering of the wheel chair is effected by separate control of both driven rear wheels  35 . Preferably, the driving force is provided by hub motors, i.e. electric motors which are provided in the hub region of the wheels (but are not shown in detail). Steering commands are input via a control panel  60 .  
         [0030]    The front arm  20  (illustrated as a dual arm) is designed in a way that the caster of the front wheel  25  remains substantially constant over the entire range of travel of the spring system.  
         [0031]    One or several storage batteries  70  can be hooked to the main body  10  via quick release devices. The quick release devices for securing the storage batteries  70  comprise interfaces for electric circuits which provide electric connection of the storage batteries  70  to the hub motors.  
         [0032]    A protection device in the form of a protective cage  80  is, preferably detachably, attached to the main body  10 .  
         [0033]    A climbing device  28  is provided at each of the front wheels  25 . There is a pair of climbing devices  28  for each front wheel  25  which is supported on both sides of each front wheel  25  and biased in a way so that under normal operational conditions they are in a position which is depicted in FIG. 6. The climbing device  28  can be pivoted over a certain distance in the direction indicated by arrow A in FIGS. 6 and 7 in the direction of rotation of the wheel with the pivotal axis indicated at reference number  29 .  
         [0034]    For the sake of simplicity, only one front wheel  25  is depicted in FIGS. 6 and 7 in order to explain the function of the climbing device  28 . When the wheel chair travels in the direction of a curb with the front wheel leading, the climbing device  28  initially is in its upper pivotal position due to the bias force of the spring. When the climbing device  28  gets in contact with curb  90 , the climbing device  28  is pivoted in the direction of rotation of the front wheel  25  due to the driving force provided by the driving wheels. As a result, the front wheel  25  is lifted until it gets in contact with the curb in an appropriate position so that upon further travel of the vehicle the curb  90  can be negotiated.  
         [0035]    Due to the fact that the climbing devices  28  are directly coupled to the freely rotatable front wheels  25 , such climbing devices  28  are always in a suitable orientation with respect to an obstacle, particularly in such cases where a curb or another step is approached at an angle. It is clear that the climbing device also can be directly coupled to the main body.  
         [0036]    The seat component  50 , the storage batteries  70 , the rear wheels  35  and the front wheels  25  can be removed by means of simple quick release devices for dismantling the wheel chair. After being removed, the seat component  50  can be folded. Accordingly, single components are provided which can be transported in a space-saving manner and which can be accommodated in the trunk of a common automobile. The ability to be easily dismantled further provides that the single components have a relatively low weight so chat the components can be easily stowed away. The provision of quick release devices facilitates dismantling of the wheel chair also for technically untalented persons and without any tools.  
         [0037]    Even though the wheel chair of the present invention is easily dismantled, it is suitable for outdoor use. It combines the comfort of four spring-suspended wheels and the stability required for outdoor operation with the low weight and transportability of a common indoor wheel chair.  
         [0038]    Although the invention has been described with reference to exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the true spirit and scope of the present invention.