Abstract:
An actuator assembly for a lifter device for disabled persons on wheelchair and prams for children comprising a vertically movable platform able to move between a lowered position and a raised position to overcome a difference in level of access. The actuator assembly comprises an electric motor and a transmission device including a chain of transmission members, provided exclusively with rotary motion.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of Italian patent application number TO2003A000759, filed Sep. 30, 2003, which is herein incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates in general to lifter devices and in particular it pertains to equipment to facilitate the access of disabled persons and children&#39;s prams aboard vehicles, for example collective transport vehicles, or to fixed installations such as public buildings, museums and the like.  
         [0004]     2. Description of the Related Art  
         [0005]     The invention can be applied in particular to a lifter device to be permanently applied to a vehicle or to a fixed installation to overcome a difference in level to access said vehicle or said fixed installation. The present invention can nonetheless be applied more in general to lifter devices of various kinds for persons or for loads, in vehicles or in private, commercial or industrial buildings. The invention can, for example, be applied in lifter devices under the body or over the body for automobiles or buses, in lifter devices over the box or under the box for trains, in buildings such as shopping centres or the like.  
         [0006]     The main drawback in actuators for known lifter devices consists of the possibility of sticking and blocking of the vertical actuation system of the lifting platform, in particular if the load on the platform is displaced on one side.  
         [0007]     The object of the present invention is to provide an actuator assembly for lifter devices which is simple, robust and reliable and which allows to avoid risks of sticking.  
       SUMMARY OF THE INVENTION  
       [0008]     According to the present invention, said object and other objects are achieved by an actuator assembly having the characteristics set out in the claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The characteristics and advantages of the present invention shall become readily apparent in the detailed description that follows, provided purely by way of non limiting example, with reference to the accompanying drawings, in which:  
         [0010]      FIG. 1  is a schematic perspective view of an actuator assembly according to the present invention,  
         [0011]      FIG. 2  is a lateral view according to the arrow  11  of  FIG. 1 ,  
         [0012]      FIG. 3  is a perspective view of a first embodiment of an actuator assembly according to the invention,  
         [0013]      FIG. 4  is a perspective view of a second example of application of an actuator assembly according to the invention,  
         [0014]      FIG. 5  is a perspective view of the part designated by the arrow V in  FIG. 4 , and  
         [0015]      FIG. 6  is a perspective view of a third example of application of an actuator assembly according to the invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     With reference to  FIGS. 1 and 2 , an actuator assembly according to the invention comprises an electric motor  40  and at least one transmission device  42 . The or each transmission device  42  is connected to two arms  44 ,  46  of an articulated parallelogram device associated to a vertically movable platform.  
         [0017]     The transmission assembly  42  comprises a fixed case  48  bearing a chain of transmission members provided exclusively with rotary motion. Each transmission device  42  comprises a first transmission mechanism with worm screw  50  and helical wheel  52 . The worm screw  50  constitutes the input member of the transmission device  42 . The first helical wheel  52  is integral with a shaft bearing a second worm screw  54  freely rotatable around an axis that is transverse relative to the axis of rotation of the first worm screw  50 . The second worm screw  54  co-operates with a second helical wheel  56  integral with a shaft bearing a third worm screw  58  rotatable around an axis that is orthogonal relative to the axis of rotation of the second worm screw  54 . The third worm screw  58  meshes with a sector of helical wheel  60  constituting the output member of the transmission device  42 .  
         [0018]     In an embodiment of the invention, two transmission devices  42  are provided, situated on two opposite sides of a vertically movable lifting platform. The toothed sector  60  is keyed onto a transverse synchronisation shaft  62  mounted oscillating relative to the case  48  of the transmission device  42  around a horizontal case  64 . The toothed sector  60  is integral with the lower arm  44  of the articulated parallelogram device. The transverse shaft  62  mutually connects the toothed sectors  60  of two transmission assemblies  42  situated on the two sides of the platform and its purpose is mutually to synchronise the oscillation movements of the two lower arms  44 . The electric motor  40  is connected to the two transmission devices  42  by means of positive drive belts  66 ,  68 .  
         [0019]     It is readily apparent that the rotation of the output shaft of the motor  40  causes the oscillation of the toothed sector  60  around the axis  64 . The toothed sector  60  commands, through the articulated parallelogram device  44 ,  46 , the rising or lowering of the platform.  
         [0020]     With reference to  FIG. 3 , the reference number  70  designates a retracting lifter device comprising a fixed frame  72  to be encased within a seat (not shown) provided below the plane of access to a vehicle or to a fixed installation. The fixed frame  72  has a general U-shaped configuration, with two parallel branches  74 ,  76  mutually joined by a rear branch  78 .  
         [0021]     The fixed frame  72  bears a carriage  80 , movable in the longitudinal direction between an extracted position and a retracted position. The carriage  80  bears an actuator assembly according to the invention, having an electric motor  40  and two transmission devices  42 . Each transmission device  42  bears two arms  44 ,  46  connected to a vertically movable platform  82  according to an articulated parallelogram configuration.  
         [0022]     The transmission devices  42  according to the present invention, mutually synchronised by means of the transverse shaft  62 , allow to avoid the sticking or blocking of the vertical motion of the platform  82  even under conditions in which the load on the platform  82  is laterally unbalanced.  
         [0023]      FIGS. 4 and 5  show a second example of application of an actuator assembly according to the invention. In this case, the actuator assembly  40 ,  42  is applied to a lifter device including a base structure  84  provided with a vertically movable platform  82  able to receive and to lift and lower a wheelchair  86 . The actuator assembly  40 ,  42  is borne by the base structure  84  and it is connected to the vertically movable platform  82  by means of the articulated parallelogram device  44 ,  46 .  
         [0024]     An additional example of application of the actuator assembly according to the invention is shown in  FIG. 6 . In this case, the actuator assembly  40 ,  42  is applied to a lifter device including a vertically movable platform borne by a vertical upright  88 . The lifter device is mounted rotatable around a vertical axis  90  and the actuator assembly  40 ,  42  is used to command the rotation of the entire lifter device around the vertical axis  90  in the direction indicated by the double arrow  92  between an inoperative position and an operative position, and vice versa.  
         [0025]     Naturally, without altering the principle of the invention, the construction details and the embodiments may be widely varied relative to what is described and illustrated herein, without thereby departing from the scope of the present invention as defined in the appended claims.