The present invention relates to a suitcase and more particularly to a suitcase comprising rigid shells rigidly connected to articulated frames. Such suitcases are typically equipped with two shells which substantially define their useful volume. The perimeter of the shells is rigidly connected to respective stiffening frames, hinged at one side to allow the opening and closing of the suitcases themselves. In order to reduce the weight of the finished suitcase as far as possible, application EP 1 867 246 in the name of the Applicant teaches how to produce thin shells adhesively secured to respective stiffening frames.

Since the shell has a shape which is simply convex (or without re-entrants), the shape of the suitcase of EP'246 has a step at the end of the frame, where the shell becomes visible, emerging from the frame to which it is fixed.

This step, besides being visually unpleasing, defines a surface which, especially on the side facing downwards when the suitcase is being dragged, may be subjected to impacts against bumps in the ground.

Moreover, the shells of such a suitcase are adhesively secured to the inside of a seat; it is therefore possible that, during the insertion of the shells into their seat, there may be leakages of adhesive material which, becoming visible on the outside, result in unattractive dribbles.

Any impacts of the frame against bumps in the ground, if they are particularly violent, may possibly _^ lead to detachment of the shell from the frame.

There is therefore a need to provide a suitcase in which the risk of impact between bumps in the ground and the end surface of the frame is reduced to a minimum, so as to diminish the risk of breakages arising from such impacts.

It is an aim of the present invention to fulfil the aforesaid requirements at least partially; this aim is achieved by means of a suitcase according to claim 1.

Further characteristics and advantages of the suitcase according to the present invention will become clear from the following description of some preferred exemplary embodiments thereof, provided by way of non- limiting example with reference to the appended drawings, in which:

Figure 1 is a side view of a portion of a suitcase according to the prior art;

Figure 2 is a perspective view of the cross-section of a suitcase according to the prior art; - Figure 3 is a perspective view of a detail in a cross- section of a suitcase according to a preferred embodiment of the present invention.

Figure 4 is a perspective view of a detail in a cross- section of the suitcase of Figure 3; - Figure 5 is a cross-sectional view of a detail of the suitcase of Figure 3.

With reference to the appended drawings, the suitcase 1 comprises two shells 2 glued to respective frames 3, articulated with one another, for example by means of hinges, and equipped with closure means (not shown) , for example zip closures or snap fasteners, in order to keep the frames 3 and, at the same time, the shells 2 closed together.

For the purposes of the present description, reference will however be made to only one of said shells 2 and frames 3, it being understood thereby that an advantageous embodiment provides for both the frames 3 of the suitcase 1 to comprise the features described hereinafter.

The shell 2 comprises an end portion 4, inserted into a suitable substantially U-shaped seat 5, provided in the frame 3 with which the shell 2 is associated. In this way, the seat 5 defines the end portion 4 as the portion of the shell 2 which is inserted into the seat 5 itself.

The shell 2 also comprises a main portion 6, substantially coinciding with the visible portion of the shell 2 itself; the main portion 6 is connected to the end portion 4 via an intermediate portion 7.

The end portion 4 is off-set towards the inside of the suitcase 1, at least at the lower side 8 of the suitcase 1, but advantageously at the entire perimeter of the shell 2. The lower side 8 can be defined as the side facing downwards when the suitcase 1 is resting on the feet or on the castors, or as the side facing downwards when the suitcase 1 is dragged by means of a pull-out handle, or as the side opposed to the shorter side equipped with a handgrip. In general, depending on the type of suitcase, it will be immediately obvious to a person skilled in the art as to which is the lower side 8 of the suitcase 1.

The intermediate portion 7 connects the end portion 4 and the main portion 6 with each other; having a length which is less than that of the end portion 4, it is particularly inclined with respect to the portions 4, 6 adjacent thereto.

Advantageously, in proximity to the intermediate portion 7, the outer surface of the main portion 6 of the shell 2 is in substantial geometrical continuation of the outer surface of the frame 3, so as to develop an efficacious effect of deflection of the blows caused by bumps in the ground.

As can be seen in Figure 5, the main portion 6 and the intermediate portion 7 form an angle α with each other, while the intermediate portion 7 and the end portion 4 form an angle β with each other. Preferably, α<β. The angle β can be between 40° and 50°, preferably β is around 45°; the angle α, however, may be slightly smaller, for example between 0.5° and 5°, and preferably α is around 1° less than β.

In one embodiment, the difference between α and β is substantially equal in both the shells; in a second embodiment, the difference between α and β is substantially different in the two shells 2.

The outer surface of the end portion 4 may be substantially in continuation of the inner surface of the main portion 6.

The shell 2 may advantageously be produced by thermoforming. Thermoforming consists in deforming a sheet of material, for example of polymer, suitably softened by the effect of heat and mechanical energy, provided for example by nozzles capable of blowing gas and/or aspirating.

In the present case the mould for the shell 2 comprises a negative, the outer shape of which is substantially identical to the inner surface of the shell 2.

This negative comprises nozzles capable of emitting working gas and nozzles capable of aspirating, not necessarily different from the nozzles capable of emitting working gas. In order to be able to produce the shell for the suitcase according to the invention, the negative also comprises a portion, corresponding to the end portion 4 of the shell 2, the surface of which is off -set towards the inside with respect to the surface corresponding to the main portion 6. In practice, the configuration of the negative has a mushroom shape.

Once the sheet of polymer has softened sufficiently, it is caused to adhere to the outer surface of the negative.

In order also to cause the end portion 4 to adhere, the surface of the negative corresponding to the end portion 4 is provided with suitable intake openings, which are capable of drawing to themselves the end portion of softened polymeric sheet.

The counter-mould does not have members for pushing the end portion 4 towards the negative, since such members would have to be movable members, extremely expensive to introduce into a mould. During the extraction of the shell 2 from the mould, the resilient deformability of the shell 2 makes it possible not to have a negative comprising movable carriages; it is optionally possible to act by means of the nozzles of the negative to impart an additional extraction force to the shell 2. The shell 2 may advantageously be made of polymeric material, for example PE, PP, ABS, PC, PC/ABS, and have a thickness of less than 2.2 mm, advantageously less than 1.9 mm, for example around 1.6 mm,- the frame 3 may advantageously be made by the injection-moulding of polymeric material, for example PE, PP, ABS, PC, PC/ABS, preferably of the same material as the shell 2.

As may be appreciated from what has been described, the suitcase according to the present invention makes it possible to fulfil the requirements and remedy the drawbacks referred to in the introductory part of the present description with reference to the prior art .

Naturally, in order to satisfy contingent and specific requirements, a person skilled in the art may apply to the configurations described above many modifications and variants, for example by applying them to a trolley or to another type of luggage. All these modifications and variants are however included within the scope of protection of the invention as defined by the following claims.