The invention concerns a method for the production of a vehicle, wherein the vehicle has a rigid, supporting framed structure and a body of plastic, with bottom, front and back parts and a roof in the case of a closed vehicle.

Vehicles, and especially cars, have traditionally been constructed of steel as the principal material and are therefore designed according to the design criteria and production methods which form the basis for the utilization of this material. This design has traditionally been based on a rigid bottom frame and body panels which have been assembled on this bottom frame. New designs have subsequently been devel- oped using so-called self-supporting bodies, i.e. with an integrated assembly of body plates and internal, matching plates which are assembled so as to provide a self- supporting and strong structure. The engine, suspension, wheeis and all the necessary equipment were then installed on and inside this structure. A further development has taken place in which attempts have been made to find other types of material and in this connection aluminium has been considered as a construction material as well as body parts of plastic. These changes of material, however, have not resulted in any significant changes in design type and the vehicles, and especially cars, which are built to-day are still mainly based on the technology which was based on steel as the building material.

Thus in connection with the further development of vehicle design there has been a need to develop new production methods which provide simpler construction and which are better suited to new and other types of material.

The object of the present invention, therefore, is to provide a new production method for vehicles, wherein the method of production of the vehicle is developed on the basis of those materials which are employed and where a simpler, faster, more efficient and preferably also a more reasonably priced production is achieved. In particular it has been an object of the invention to provide a method which is especially well suited to the production of small, light vehicles, e.g. electric cars. This object is achieved with a method of the type mentioned in the introduction, which is characterized by the features in the patent claims.

In the present invention an entirely new starting-point is taken for the production of a vehicle and untraditional design criteria, modern materials as well as production methods have been used which thus far have not been employed in connection with

vehicle production. The basis of the invention is to build up a rigid, supporting frame, e.g. according to the principle which in recent times has also been considered by the car industry, viz. the so-called "space-frame" system. In the main this system uses extruded aluminium profiles which are assembled in a suitable manner and adapted to one another for a practical and rational installation, the profiles being designed to provide the appropriate strength and deformation conditions. The construction may also include outer elements which are visible in the finished construction. On a bottom frame there is built up a framework, also preferably of extruded aluminium profiles, which constitute a supporting structure and will form a kind of -reinforced cage around the vehicle's cabin. In an open vehicle this framework will be adapted to suit this open design. The design will give access for attaching the other mechanical components and the system which is necessary for the final vehicle both with regard to its operation and in connection with the safety of the vehicle. To the bottom frame there are therefore attached suspension systems, driving wheels, a steering unit, possibly a drive unit and drive energy supply, etc., according to requirements. The actual cabin or the body of the vehicle is made of plastic. It has been shown to be particularly advantageous to use thermoplastic ductile plastic material which preferably includes a total body including bottom, side walls, front and back parts and the roof in the case of a closed vehicle. Alternatively this body can be made of a plurality of parts or plates in such a manner that the assembly is performed in a separate operation before the actual mounting on the bottom part of the frame.

The invention will now be explained in more detail by means of an embodiment, which is illustrated in the drawing, in which:

Figure 1 illustrates the three main components of a vehicle before these are assembled according to the invention, figure 2 is a schematic illustration of the assembled vehicle and figure 3 illustrates another design of the vehicle's frame parts.

The drawing presents a purely schematic illustration of the main concept of the invention. The way in which the principal part is constructed is therefore not illustrated in any detail, since known methods will be employed for this purpose. Thus a number of methods and devices exist for the production of a framework of, e.g., aluminium profiles and the individual features which will be included in such a framework are also not described in any detail, there being many possibilities here within the scope of the invention. The underbody of the frame will therefore be designed with deformation zones in order to secure the vehicle in case of collision, and reinforcing elements of

various kinds will also be included. It will be possible for a person skilled in the art to vary these design features. With regard to the actual body, as already stated this is preferably made of thermoplastic and can, e.g., be manufactured by means of rotational moulding, as in the case of, e.g., small boats and the like. It is an advantage for the plastic to be coloured throughout.

The vehicle's framed structure is composed of a frame bottom part 1 and a frame upper part 2. The vehicle's plastic body which is preferably formed in one piece, but which may be prefabricated of several elements, is generally indicated by 3. The shape of the frame bottom part 1 will be dependent on the type of vehicle which has to be produced. In general, however, this bottom part will be equipped with at least one set of upwardly projecting posts 4,5. The posts are in pairs on the two sides of the vehicle and will subsequently form the attachment points for the body, preferably on both sides of the location which will form the door opening in the body.

The vehicle body 3 is mounted on the frame bottom part 1. The former is located on the frame bottom part 1 in such a manner that the bottom of the body will abut against the frame bottom part and partially rest on it and be supported by it. As mentioned, the body 3 is designed with a complete bottom and will thereby lie sealingly against the base. Before the body 3 is mounted, necessary equipment, such as the suspension system, steering, the engine and wheel suspension are mounted on the bottom part 1.

After the body 3 is in position, the upper frame part 2 is mounted. This is illustrated schematically in figure 1. This part preferably also has at least one set of posts which project downwards and which are indicated by 6 and 7. These posts are designed to be brought into abutment against the posts 4 and 5. The frame part 2 is inserted into the body part by being passed in through the window opening as illustrated by arrow A or in through a planned rear opening as indicated by arrow B. In other words the frame upper part is adapted in such a manner that it will be able to be passed into the body. In order to obtain the desired reinforced cage for a closed vehicle, posts 4 and 6 and 5 and 7 are joined together, e.g. by welding, riveting, bolting or by means of securing flanges or nuts, thus providing a rigid construction. This can be done very rapidly and efficiently since there are only two frame parts which have to be joined together. Further reinforcements may be provided or further posts can be provided on the frame parts or other construction beams in order to provide further reinforcement in the rear section or the front section.

Figure 2 illustrates schematically how the framed structure will be located in the body, which is indicated here by dotted lines. The point of attachment is indicated by 8. In an open construction the upper part of the upper framed structure can be omitted, with reinforcements only around the windscreen and possibly a roll bar at the rear post 5. Other reinforcing elements may also be attached according to the nature of the construction.

Figure 3 illustrates a possible design wherein the upper frame part does not have downwardly projecting posts in the same manner as in figures 1 and 2, but is designed with different kinds of reinforcing elements. At the front edge there is an oblique reinforcing post 9, which constitutes a fastening for front windows, while at the rear edge there is mounted a profile beam 10, which supports the rear edge of the vehicle and is also attached to the frame bottom part 1 at a point further forward. A design of this kind can be suitable for securing, e.g., a push-in box for batteries or the like. Many modifications will be possible within the scope of the invention. In figures 1 and 2 the posts are indicated as approximately vertical, but they can, of course, also form an angle, even in relation to each other. With regard to the actual joining of the body and the framed structure, several alternatives exist. The most advantageous is the use of the hooking together design which is described in the applicant's Norwegian patent application no. 893155 wherein by means of hooking and clamping means a simple clamping and securing of the plastic body's open edge to the framed structure's profile beam is performed. Thus the body can be firmly secured to the framed structure by simple means. With the illustrated post construction excellent reinforcement with easy access for joining will thereby be obtained in the door opening, while at the same time the posts constitute the beams required for attachment of the doors. Thus there will always be a need for an upwardly projecting post and bottom part of the framed structure for mounting of doors, regardless of whether an open or a closed body is involved.