Abstract:
A transporting device has wheels, a stair climbing unit having climbing legs, an electric motor provided for driving of the stair climbing unit, a drive shaft which is driven by the electric motor and is formed as a crank shaft located symmetrically to a central longitudinal axis of the device, the drive shaft having halves each rotatably supporting a first crank for the climbing leg and a second crank for the wheel.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a transporting device which has wheels and a stair climbing unit Which is driven by an electric motor and provided with climbing legs. 
     Transporting devices with step climbing units are known in many modifications. One of such transporting devices is disclosed in German patent document DE 37 13 564, and used in particular for a wheelchair. It is provided on both sides with a wheel pair whose wheels are turnable around special, jointly driven spaced parallel shafts. The shafts are connected each eccentrically with a hub disc, on which a rim of associated wheel is concentrically and rotatably supported. 
     The German patent document DE 197 45 153 discloses another transporting device which has wheels arranged on a frame and a stair climbing unit driven by an electric motor. The electric motor drives first eccentric lever, on which correspondingly a second eccentric lever is rotatably transported. It is rotatably supported with its end on supports which are linearly guided on the transporting device. Toothed gears or chains are arranged between the first and second eccentric levers. These transporting devices have a common feature that they require a relatively expensive construction with the use of chains or toothed gears. Moreover, a relatively great electric motor for the stair climbing unit is needed. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of present invention to provide a transporting device of the above mentioned general type, which eliminates the disadvantages of the prior art. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a transporting device in which the electric motor drives a drive shaft which is formed as a crankshaft symmetrical to the central longitudinal axis of the device, and on each half of the drive shaft on a crank climbing leg and on a further crank a wheel is rotatably supported. 
     Since the drive shaft formed at a crankshaft moves up and down both the climbing legs and the wheels, an expensive power transmission by means of chains or gears is dispensed with. The stair climbing unit can be produced in a price-favorable manner and also not susceptible to disturbances. A further advantage of the transporting device when compared with the German document DE 37 13 564 is that the climbing legs take up the load with smaller distances before the next stage. Thereby the horizontal extension between the supporting leg and the wheel set on the next step is shortened. The loading change at the hand grips is therefore substantially reduced. 
     The cranks for lifting and lowering of the wheels can enclose for example an angle of substantially 180° with the cranks for lifting and lowering of the climbing legs. When both the wheel cranks and the climbing leg cranks have the same length, the required torque and the motor power is minimal. When compared with the transporting device disclosed in German patent document DE 197 45 153, the required torque and the motor power is half as high. Finally, the transmission and the accumulator can be dimensioned correspondingly smaller. Thereby the weight or the total transporting device is reduced. Moreover, the accumulator can have a lower power and a shorter charging cycle. 
     For guiding the climbing legs on the device, they can be raisable lowerable, preferably along the guiding rails. Furthermore, for reducing the friction between the climbing legs and the guiding rails, the climbing legs can be guided preferably with guide rollers along the guiding rails. 
     Alternatively to a guidance on a rail, the climbing legs can be guided for example also by a guiding crank supported on a frame for lifting and lowering movements. This guiding crank which is arranged not on the crank shaft rotates parallel to the climbing leg cranks. 
     The guiding cranks and the cranks for lifting and loading movement of the climbing legs can be connected with one another by a chain or a transmission band. Thereby it is prevented that the guiding cranks and the climbing leg cranks are in an unstable position, when the guiding cranks and the climbing leg cranks are oriented in one line. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a transporting device with a stair climbing unit in accordance with the present invention; 
     FIG. 2 is a view of second embodiment of transporting device with a stair climbing unit; 
     FIG. 3 is a view of the transporting device of FIG. 1 as seen from behind; and 
     FIGS. 4-11 are side views of the transporting device of FIG. 1 in different positions during climbing a stair step. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows a transporting device  10  with a step climbing unit  31  which is shown in detail in FIG. 3, during climbing of a stair step  1 . The transporting device  10  has a frame  12  for receiving a not shown load. Furthermore, it has two wheels  17  and two climbing legs  15 . Only one of them is shown on the side view. The wheel  17  is lifted and lowered by the electric motor  13  and a transmission, via the crank  14  and the climbing leg  15  via a crank  16 . The climbing leg  15  is provided with a guiding roller  18  on its upper end, which is guided in the guiding rail  19 . 
     FIG. 2 shows an alternative embodiment of a transporting device  20 . It is different from the transporting device  10  of FIG. 1 in the guidance of the climbing leg  21 . The motor  13  moves the wheel  17  through the crank  14  and lifts and lowers the climbing leg  21  via the crank  16 . Parallel to the climbing leg crank  16 , a guiding crank  22  rotates. It is rotatably supported on a climbing leg  21  and on the frame  24  of the device  20  and holds the climbing leg  21  always in an approximately vertical position. The climbing leg crank  17  and the guiding crank  22  are coupled with one another via a chain  23 . This coupling prevents that the cranks  16  and  22  can be blocked in a point in which the crank  16  and  22  are located on one line. 
     FIG. 3 shows a rear view of the stair climbing unit  31  of the transporting device  10  of FIG.  1 . The step climbing unit  30  has a motor  13  in which the transmission is also integrated, and a shaft  30  which is formed as a crankshaft. The crankshaft  30  is formed symmetrically to the central longitudinal axis of the device  10 . It has cranks  14  for lifting and lowering of the wheels  17 , and cranks  16  for lifting and lowering of the climbing leg  13 . The cranks  14  and  16  are arranged on the shaft  30  so that they are offset relative to one another by 180°. The climbing legs  15  are guided in their upper region by guiding rollers  18  in the guiding rails  19  which are shown in FIG.  1 . 
     An operation of the transporting device  10  is illustrated in FIGS. 4-11. In FIG. 4 the transporting device  10  with a load  40  is in a stationary position. The wheel  17  is located directly before the edge of a stair step  41 . In FIG. 5 the transporting device  10  is inclined and the motor is turned on. Thereby the crankshaft  30  is rotated. It produces the situation shown in FIG. 6, wherein the climbing leg  15  is moved downwardly and the transporting device  10  is lifted. Simultaneously, with downward movement of the climbing leg  15 , the wheel  17  is moved upwardly. In FIG. 7 the climbing leg  15  is in its lowest point and the wheel  17  reaches its highest point. Thereby the lowest point of the wheel  17  is located over the upper edge of the next step of the stairs  1  to be climbed. In the position shown in FIG. 8 the wheel  17  is again moved somewhat downwardly and the climbing leg  15  is moved somewhat upwardly. Thereby the wheel  17  is placed on the step of the stairs  41 . The climbing leg  15  still stands on the preceeding stair step. 
     FIGS. 9-11 show how the climbing leg  15 , due to the further rotation of motor  13  and the crankshaft  30 , is moved upwards and the wheel  17  is moved further downwards. Thereby the transporting device  10  is lifted on the new step of the stairs  41  to be climbed. The climbing leg  15  is pulled in. FIG. 1 shows the climbing leg  15  in its upward apex point and the wheel  17  in its lower apex point. Thereby the transporting device  10  and the load  40  reach their highest point on the newly climbed step of the stairs  41 . During climbing of the next step, the cycle shown in FIGS. 5-11 is repeated again. 
     When the transporting device  10  must move down the stairs, the rotary direction of the motor is switched over, and the movement sequence is performed in an order which is opposite to the order shown in FIGS. 5-11. When necessary, the device  10  can be also provided with a brake for the wheels  17 . 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in transporting device, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.