BACKGROUND ART There are known lifting devices and apparatuses substantially constituted by a platform connected to the vehicle frame by means of suitable mechanisms and driven by actuators between a lowered position and a raised position, according to an almost rectilinear and vertical trajectory.

A disadvantage of the above known devices consists in that they are very bulky and heavy and, thus, they can be installed only on some types of vehicles, after suitable and important adjustment works, which are very expensive.

Other disadvantage consists in that in folded or unused condition, said devices are bulky release hindrance and, however, they are aesthetically unpleasant to see.

DISCLOSURE OF THE INVENTION An object of the present invention is to propose a lifting device which is compact and light, thus adapted to be installed on a wide range of different vehicles with minimal adjustment works.

Other object consists in proposing a device which can be easily modified and adapted, in accordance with the specific demands, safe and reliable.

Further object is to propose a device having, in a internal condition, a compact configuration, with reduced dimensions and low visibility.

The above-mentioned objects are achieved in accordance with the claim content.

BRIEF DESCRIPTION OF THE DRAWINGS The characteristics of the present invention are underlined in the following with particular reference to the attached drawings, in which: - figure 1 shows a side view of the lifting device of the present invention associated to a vehicle in an external condition and with a platform in a raised position; - figure 2 shows a side view of device in figure 1 with the platform in an middle position; - figure 3 shows a side view of device in figure 1, in which some elements have been removed for better underlining others and with the platform in a lowered position; - figure 4 shows a side view of device in figure 1 in a internal condition; - figures 5 and 6 show respectively a plan top view and plan bottom view of figure 1 device, in which some elements have been removed for better underlining others.

BEST MODE OF CARRYING OUT THE INVENTION With reference to figures 1 to 6, numeral reference 1 indicates the lifting device for an user associated to a vehicle 100 and substantially constituted by lifting means 2, provided with a platform 3 for lifting the user, and with translation means 4 for moving said lifting 2.

The lifting means 2 are sliding supported by support means 5, fixed to a lower portion of vehicle 100, and they include a carriage means 10 and two couples of shaped levers, first 12 and second 13, positioned at the two sides of said carriage means 10. The levers have an approximately bent shape and they have ends rotatably coupled'to the carriage means 10 and to the platform 3, respectively, so carrying out two articulated quadrilateral.

At each side of the carriage means 10, the lifting means 2 include a couple of connecting rods, first 17 and second 18, which are synchronously driven by first actuator means 15 through transmission means 16 and they are connected to the levers, respectively first 12 and second 13.

The transmission means 16 are constituted at least by a chain or timing belt which connects first cogwheels 33 fixed to each connecting rod 17,18.

The first actuator means 15, of electric or pneumatic or hydraulic rotating type, rotate a couple of pinions 20, each of which is connected to the respective second connecting rod 18 by second transmission means 21. Particularly, the second transmission means 21 consist of a chain

connecting each pinion 20 to a second cogwheel 34 integral with the respective second connecting rod 18.

A train of gears can also constitute the first transmission means 16 and second transmission means 21.

Preferably, the output shaft of first actuator means 15 is connected to one or more speed reduction unit 19, for instance of worm screw type or of epicycloidal type. The speed ratio between the pinion 20 and the second cogwheel 34 can be opportunely defined for further reducing the output revolution number and for obtaining an advantageous torque operating on the connecting rods 17,18.

The support means 5 have a plurality of sliding guides 22 for slidingly supporting corresponding sliding means 23 of carriage means 10 of lifting means 2. Particularly, the sliding means 23 consist of free wheels or rolls engaging the guides 22.

The translation means 4 include a couple of transmission elements 25, which are driven by second actuator means 26, of electric or pneumatic or hydraulic rotating type, and which are coupled to lifting means 2. Particularly, each transmission element 25 consists of a chain or of a timing belt rolled around return pulleys 27 and operated by second actuator means 26 through a respective pinion 28. The rotation of chain 25 causes the translation of the lifting means 2 coupled thereto.

In alternative, the translation means 4 may include screw nut-screw means, of known type and not shown, rotated by the second actuator means 26 and whose nut screw is connected to the lifting means 2 for their translation.

The output shaft of the second actuator means 26 can be coupled to a second speed reduction unit 29, for instance of worm screw type, in order to reduce and to more carefully control the translation speed of lifting means 2.

The translation means 4 can also consist of a linear actuator of electric or pneumatic or hydraulic type.

The device 1 has one or more brackets 31 for fixing the support means 5 to the lower portion of

vehicle 100.

There are further provided sensor means 30 fixed to a lower portion of platform 3 and capable to sense the presence of ground or of possible obstacles.

Electronic control means are connected to the actuator means, first 15 and second 26, and to sensor means 30 for automatic driving the device 1.

Interface means are also provided, of known type and not shown, connected to the electronic control means in order to allow an user to activate and to deactivate the device 1.

There are alarm means connected to the lifting means 2 and to a speedometer or a gearbox or an instrument panel of vehicle 100, in order to provide an alarm signal in correspondence of all the working positions of lifting means 2 in the external condition E with the vehicle 100 moving.

The operation of lifting device 1 of the present invention provides that the translation means 4, driven by second actuator means 26, move the lifting means 2 between a internal condition R, wherein they are arranged underneath the lower portion of vehicle 100, and an external condition E, wherein the lifting means 2 are externally arranged and placed side by side the vehicle 100.

In said external condition E, the operation of first actuator means 15, which move the shaped levers 12 and 13 by the connecting rods 17 and 18 and the transmission means first 16 and second 21, allows to move the platform 3, along a direction almost orthogonal to the ground, at least between a lowered condition B, wherein said platform 3 is at minimum distance from the ground in order to allow an user to easily mount the platform 3, and a raised condition A, wherein the platform 3 is at the maximum distance from the ground, namely near to an entry of the vehicle 100.

The lifting motion of platform 3 can occur only in the external condition E of device 1.

It must be noted that the shaped levers 12 and 13, carrying out with the platform 3 and with the carriage means 10 an articulated quadrilateral, allow the platform 3 to stay perfectly parallel to the ground always, in any operational position thereof, between two extreme conditions, lowered B and raised A. Furthermore, the platform 3 moves in accordance with an curved

trajectory, which allows said platform 3 to avoid possible external encumbrances of the vehicle 100 during the up and down movements.

The presence of sensor means 30, fixed to a lower portion of platform 3, allows to detect the presence of the ground or of possible obstacles and to send a stop signal of the descent of platform 3 to electronic automatic control means of device 1; the electronic control means are connected to the first actuator means 15.

Likewise the alarm means provides an alarm signal in the external condition E with the vehicle 100 moving, in order to avoid impacts and collisions of platform 3 against objects and people.

An advantage of the present invention is that to provide a lifting device that is compact and light thus which is adapted to be installed on a wide range of different vehicles with minimal adjustment works.

Other advantage is to provide a device which can be easily modified and adapted, in accordance with the specific dimensions requirements and which is characterized by a safe and reliable operation.

Further advantage is to provide a device having, in a internal condition, a compact configuration, with reduced dimensions and low visibility.