Using of doors as structural members of the car's frame

This invention relates to the technical field of designing and manufacturing of car frames and it is about a method and a system to increase their rigidity. This method makes use of the car's doors as part of the frame structure; while at the same time maintain their main function.

This system improves the car's frame rigidity to a great extent, reduces weight, increases passenger's safety and eliminates the possibility of the doors get unlocked during an accident and it can also replace the current door locking mechanisms.

As it is known the car's frame is the skeleton on which the car vehicle is build up, it's rigidity is the base on which all parameters of energetic and passive safety is based upon. For this reason the improvement of frame's rigidity in conjunction with weight saving, are the first tasks of all car manufacturers.

Up to day with the existing technical level, the monocoque type car frames base their rigidity either exclusively or partially on the floor pans. The open type cars (without permanent roof top) base their rigidity exclusively on the floor pan, while in the closed type cars (with permanent roof top) the rigidity of floor pan is reinforced by the contribution of the roofs strength through the side pillars. These additional elements, strengthen the frame, change the form of the car's frame and improve to a large extent its rigidity.

As a result of the decreased rigidity of open cars, compared to the closed ones, the weight of the cars is dramatically increased, through the strengthening of the floor pans to obtain an acceptable level of rigidity. The strengthening, by several methods and ways, of the existing elements of car frames like the floor pan for the open types and the roof with the side pillars for the closed ones, is the only way the designers and the car manufacturers up to now have to improve rigidity. The scope of this invention is the improvement of car's frame rigidity with the introduction of new elements in the frame structure and these new elements are the car's doors.

With the present technical level of today, the doors are simply suspended on the main frame and they are not used as integral parts of the frame, because either this idea never occurred or if it occurred, the method end the system of incorporating the doors to be parts of the car's frame were not invented, which would have allowed the use of the doors to be part of the frame and at the same time perform their main function.

The use of the doors as structural elements of the car's frame, will result in that the open roofed cars which have a form of "U" shape, will now become a closed frame and the closed ones will have smaller openings, the two frames (open and closed) will have more longitudinal and transverse strengthening with obvious gains, the improvement in rigidity.

The use of doors as structural elements of the car's frame, while at the same time keeping their main function, this invention makes use of "Using of doors as structural members of the car's frame" is described in a brief and general way.

1. It uses a method, to improve the car's frame rigidity, using the doors as structural elements of the frame.

2. It uses a system for the application of this improved rigidity method using the car's doors as structural elements of the frame, which is comprised from: a. Hollow beams systems (13, 14 & 15) which are introduced to each one of the doors (1) of the car and to the opposite of them vertical (2) and horizontal (3) elements of the frame and b. A control unit of the hollow beams systems (13, 14 & 15).

The hollow beams systems (13, 14 & 15) are:

1. System of five hollow beams (13) (FIG. 1, 2, 7 & 8), which is made up from one or more subsystems of five hollow beams (16).

2. System of three hollow beams (14) (FIG. 3, 4, 9 & 10), which is made up from two or more subsystems of three hollow beams (17).

3. A combined system of hollow beams (15) (FIG. 5, 6, 11 & 12), made up from at least one subsystem of five hollow beams (16) and at least of one subsystem of three hollow beams (17).

Each subsystem of five hollow beams (16), is made up from three fixed hollow beams (4 & 5), which are attached or firmly fixed, the one (4) in the doors frame (1) as an integral part, while the other two (5) are structural members of the vertical elements (2) of the car's frame, from two movable hollow beams (7), which are installed inside the door's (1) fixed hollow beam (4), two moving mechanism (8) and four securing mechanisms (9) of the movable hollow beams (7).

Each subsystem of three hollow beams (17), is made up from two fixed beams (4 & 5 or 4 & 6), which are attached or fitted and are, the one (4) structural member of the door's frame (1) and the other (5 or 6) structural member of the vertical (2) or the horizontal (3) elements of the car's frame respectively, from one movable hollow beam (7), which is positioned inside the door's (1) fixed hollow beam (4), from one moving mechanism (8) and two securing mechanisms (9) for the movable hollow beam (7).

The three fixed hollow beams (4 & 5) of each of the five hollow beams subsystem (16) and the two fixed hollow beams (4 & 5 or 4 & 6) of each subsystem of three hollow beams (17), are of the same shape of equal inner cross sectional area, and equal thickness and are installed in, such a way as to be in alignment with each other in the three dimensions in space, the movable hollow beams (7) have the shape of the fixed hollow beams (4, 5 & 6) of subsystem (16 & 7).

In the five hollow beams (16). subsystems, the fixed hollow beam (4) of the door's frame (1) has two locking holes (11), the fixed hollow beams (5) of the vertical elements (2) of the car's frame have one locking hole (12) and the movable hollow beams (7) have two locking holes (B & K).

At the three hollow beams (17) subsystems, the fixed hollow beams (4) of the door's frame (1) and the fixed hollow beams (5 & 6) of the vertical (2) and the horizontal (3) elements of the car's frame have one locking hole (11 & 12)

respectively and the movable hollow beams (7) have two locking holes (B & K).

The moving mechanisms (8), are taken from the existing technical level, and move the hollow beams (7) from the "off ¹ position to the "on" position and vice versa and also the securing mechanisms (9), taken from the existing technical level, secured (lock) the movable hollow beams (7) to the "on" and "off' positions using locking pins (10) through the locking holes (11 , 12, B & K).

The car's computer is used as control unit and is programmed in accordance with the operational method of the systems and the needs to keep the ability of the doors to operate under normal conditions but also in under extreme conditions like that of an accident, and it controls the moving mechanisms (8) and also the securing mechanisms (9). The above described systems of hollow beams (13, 14 & 15), make the doors structural elements of the car's frame, keeping at the same time their main function by the following described way.

It strengthens the door's frame (1) in such a way as to result in a strong and stiff element of the car's frame using, any way and method taken from the existing technical level and is formed in such a way as to be ready to accept the hollow beams systems (13, 14 & 15). The same is done for the vertical (2) and horizontal (3) frame's elements. The movable hollow beams (7) of the subsystems (16 & 17) are used as a mean to bridge the door's (1) fixed hollow beams (4) with the fixed hollow beams (5 & 6) of the vertical (2) and horizontal (3) elements of the car's frame. For this purpose the movable hollow beams (7) are moved by the moving mechanisms (8) and are secured (locked) by the securing mechanisms (9), in order to:

In the "on" position (FIG. 2, 4, 6, 8, 10 & 12), to bridge strong and rigid the fixed hollow beams (4), which are structural elements the door's frame (1), with the fixed hollow beams (5 or 6) which are structural elements of the vertical elements (2) or the horizontal (3) ones of the frame. In this position they are secured with the securing mechanisms (9) by the locking pins (10) through the locking holes (12 & B) and (11 & K) of both the fixed hollow beams (4, 5 & 6) and the movable hollow beams (7).

In this way this invention makes the car's doors (1) structural elements of the frame, preventing their opening, because at the same time the system functions as a door's securing system (1) and locks the car's doors rendering the classic locks obsolete.

In the "off' position (FIG. 1, 3, 5, 7, 9 & 11) the moving hollow beams (7) of the subsystems (16 & 17), are inside the fixed hollow beams (4) of the doors (1), secured in this position by the locking pins (10) of the securing mechanisms (9), inside the locking holes (11) of the fixed hollow beams (4) of the door (1), and inside the locking holes (B) of the movable hollow beams (7).

At this position the system is inactive, the movable hollow beams (7) do not bridge one or more of the fixed hollow beams (4) of the door (1) with the fixed hollow beams (5 & 6) of the vertical (2) and horizontal (3) elements of the frame, the doors (1) do not function as an integral part of the frame and they are can be

opened.

The above implementation of this invention does not prevent any other implementation and application, in accordance with the general principles which have been described at it's presentation.

Indicative and not limiting we mention below some characteristics of the modifications and combinations which can be introduced in the above implementation, if it thinks so, the designer or constructor. 1. Each designer-constructor can choose any combination of the hollow beams systems (13, 14 & 15) or subsystems of the hollow beams (16 & 17), for implementation to all type of cars, either sedans or convertibles.

2. The fixed hollow beams (4, 5 & 6) of both subsystems of hollow beams (16 & 17) could be not of special manufacture and are mounted or riveted on the door's frame (1) and to the respective vertical (2) and horizontal (3) elements of the car's frame but by construction to be part of the door (1) and to the above (2 & 3) elements of the frame after they have been previously formed to a hollow beam. 3. To increase the rigidity of the subsystems of hollow beams (16 & 17), more securing mechanisms can be used (9) out of the least required for each subsystem (16 & 17), by increasing the relevant locking holes (11, 12, B & K) thus keeping the analogies of the application of the above invention. The securing mechanisms (9) can be installed either on the fixed hollow beams (4, 5 & 6) or inside the movable hollow beams (7).

4. To deal with any problem of twisting, momentarily or permanently, the movable hollow beams (7) can have a conical tip and can be inserted inside the fixed hollow beams of the car's frame (5 & 6), which can have a slightly larger opening to facilitate it's insertion and are near the door's (4) fixed hollow beam, also the locking pins (10) of the securing mechanisms (9) can have conical tips.

5. The movable hollow beams (7) and the moving mechanisms (8), of each subsystem (16 & 17), if there is enough available space, when are in the "off' position, can be positioned inside the fixed hollow beams (5 & 6) of the vertical (2) and horizontal (3) elements of the car's frame while in the "on" position can be moved inside the fixed hollow beam (4) of the door's frame (1).

6. The walls of all the hollow beams (4, 5, 6 & 7) could be of not equal thickness but can vary at certain chosen points or sections, or their walls can have openings either for rigidity reasons or for controlled deformation.

For increased rigidity the movable hollow beams (7) can have internal strengthening taken from the existing technical level or could not be hollow but solid.

7. The securing mechanisms (9) can use for locking pins (10), any mean and method from the existing technical level.

8. For the improvement of frame's rigidity in conjunction with the cost decrease, an implementation of this invention can be chosen, using a system of three hollow beams (14), comprising from a subsystem of three hollow beams (17) for each

door (1), which is installed at the rear of the door. In this case the bridging of the door (1) with the vertical elements (2) of the car's frame which are in front of the door is made by the door's hinges (1) strengthened with means or method taken from the existing technical level.

9. At any system of the hollow beams (13, 14 & 15) a moving mechanism (8), can be used, common to the subsystems of the hollow beams (16 & 17) for each door or common for each system of hollow beams (13, 14 & 15) of the car at it's total. 10. At any close car with strengthening of the frame around the door's window (1), taken from the existing technical level an implementation can be used which uses one or more subsystems of three hollow beams (17), so as to bridge the upper part of the door's frame (1), with the upper horizontal element (6) of the car's frame, in other words the car's top (roof).

11. The control unit of the whole system can be autonomous comprising from en electronic circuit board and a switch enabling the driver to send orders. The switch is of two positions type (on-off) and the electronic circuit board is programmed in accordance with the principles and method of the operation of this invention.

12. The above invention, apart from cars, it can be used to improve the rigidity, be used as a locking device of any truck, or machine or boat or any make, on which doors are used and rigidity is a prerequisite. This invention applied to open roof cars converts the structure and form of the frame, changing it from open and discontinued, and of "U" shape (looking from the side), to closed and continue, having joined rigidly the unconnected(with the existing technical level), vertical elements of the frame around the doors, it strengthens particular strategic points of the car's frame with obvious gains in improvement of the rigidity and reduction of weight, because there is no need for stronger floor pans.

When applied to closed cars, the openings at the frame become smaller, having joined rigidly, the unconnected (with the existing technical level), vertical and horizontal elements of the frame around the doors, which are important strategic points, gaining profits similar with that of open cars.

Apart of the improvement of rigidity of car's frame and reduction of weight, another big advantage of this invention is the strengthening of the passenger's cabin resulting in improvement of passive safety of the passengers.

Finally, another big advantage is that it eliminates the possibility of the doors getting unlocked, to all the cars, this invention is applied, in the case of an accident, because the system is used as a locking device as well in the car's doors eliminating the classic type locks.

This invention is described in details below, with the help of three examples of it's implementation and with reference to the attached drawings, which show longitudinal cross sections of three systems of hollow beams (13, 14 & 15) and their application to a door (1) and the around of this vertical (2) and horizontal (3) elements of the frame of a two door open roof car, like below.

The FIG. 1 shows a system of five hollow beams (13), comprising from a subsystem of five hollow beams (16), in the "off' position, the FIG. 2 shows the same system (13) in the "on" position, the FIG. 7 shows this application of the above system (13), in a door (1) and to the vertical elements (2) of the frame in a state in the "off position and the FIG. 8 shows the same application of the system (13) in the "on" position.

The FIG. 3 shows a system of three hollow beams (14) comprised of three subsystems of three hollow beams (17), in the "off" position, the FIG. 4 shows the same system (14) in the "on" position, the FIG. 9 shows the application of the above system (14) in a door (1)' and around it the vertical (2) and horizontal (3) elements of the frame in the "off' position and the FIG. 10 shows the same application of the system (14) in the "on" position The FIG. 5 shows a combined system of hollow beams (15), comprised of a subsystem of five hollow beams (16) and one subsystem of three hollow beams (17), in the "off' position, the FIG. 6 shows the same system (15) in the "on" position, the FIG. 11 shows the application of the above system (15) to a door (1) and around of it the vertical (2) and horizontal (3) elements of the frame in the "off position and the FIG. 12 shows the same application of the system (15) in the "on" position.

These drawings have been made exclusively for understanding this invention only, so the real analogies were not followed to show the actual size of the drawings and secondary elements are not shown, like the openings in the hollow tubes for the routing of the power cables and the signal cables that go to the auxiliary devices, the installation of the sensors and the control unit with it's connections, and also the door hinges, because all these are derived from the existing technical level and the addition of all of them would have caused difficulties in understanding the drawings of this invention.

In all the drawings, at the "off position, the locking holes (11) are not visible like the ones of the fixed hollow beams (4) or the ones of the door (1) and the locking holes (B) or the movable hollow beams (7), because the locking pins (10) are visible in their place which have them locked at this position and in the "on" position no locking holes are visible (11 , 12, B & K), instead the locking pins (10) are visible, having locked the movable hollow beams in this position.

In the first example of the application of this invention (FIG. 1 , 2, 7 & 8) an implementation of this invention is presented with a system of five hollow beams (13), and for each door, a subsystem of five hollow beams (16) is needed and described as follows.

A) Door's frame (1) The door's frame (1) is designed in such a way as to be ready to accept the fixed hollow beam (4) of subsystem (16) and is strengthened, with any way and method taken from the existing technical level, to improve rigidity.

B) Vertical elements of the car's frame (2) The vertical elements (2) of the frame are designed in such a way, from the existing technical level as to be ready to accept inside them the fixed hollow

,

7 beams (5) of subsystem (16) and are strengthened with ways and methods from the existing technical level for the improvement of their rigidity.

C) Hollow beams (4, 5 & 7) C1) Fixed hollow beams (4 & 5) - Construction and installation

The three fixed hollow beams (4 & 5) of the five hollow beams (16) subsystem, are square in cross section with constant the inside diameter and apart from the length, equal in dimension. They are installed in place, as it is defined below, in such a way as to be in line to one another in all three dimensions in space.

The one of the fixed hollow beam (4) is positioned inside the door frame (1) secured with any convenient way allowed by the present technical level in such a way as to be an integral part of it. The length (4) is exactly that of the door's frame (1) length, so that the two ends are flush with the ends of the door's frame (1 ).

The other two fixed hollow beams (5), are riveted or installed rigidly with any convenient way allowed by the present technical level, in special housings conveniently shaped at the proper points of the relevant vertical elements (2) of the door's frame (1), which surround in the front and in the rear the same door, in such a way as to comprise an integral part of the car's frame.

Also, the fixed hollow beams (5) of the vertical elements (2) of the frame, are flush with the car's frame to eliminate any gap among them (5) and the fixed hollow beam (4) of the door's (1) frame, which could introduce fatigue to them and reduction of the required rigidity.

The length of the fixed hollow beams (5) of the vertical elements (2) of the frame is not standard, but it depends on of the available space for their installation and the required demands for rigidity of each car manufacturer. The door's (1) fixed hollow beam (4) is open at both ends, while the fixed hollow beams (5) of the vertical elements (2) of the frame are open only at the end that faces the door (1).

C2) Movable hollow beams (7) - Construction and installation.

The two movable hollow beams (7) of subsystem (16) are of the same construction and type with the three fixed hollow beams (4 & 5) and are installed inside the door's (1) fixed hollow beam (4), in such a position so that their ends are flush with the doors hollow beam ends.

The dimensions of the external cross sectional area of the movable hollow beams (7) should be as close as possible with the dimensions of the internal cross section of the fixed hollow beams (4 & 5) of subsystem (16), so that the clearance between, the fixed and movable hollow beams to be very small and actually touching each other in order to facilitate movement without a lot of friction and avoid big clearances between them, which could produce a lot of movement and decrease rigidity at first place and second it could become a source of unwanted noise, introduced from the subjection of heavy loads and great flexing of the car's frame.

The length of the movable hollow beams (7) is not standard but it should be as long as it is required by the individual car manufacturer so that during operation to be able to bridge as rigidly as possible the fixed hollow beams (5) of the vertical elements (2) of the frame, with relevant fixed hollow beam (4) of the door's (1) frame.

C3) Common characteristics and operation of the fixed (4 & 5) and movable hollow beams (7)

The material and their wall thickness of the fixed hollow beams (4 & 5) and the movable hollow beams (7) could be any that will satisfy the needs of each car constructor, depending on the hardness and rigidity characteristics the system of five hollow beams (13) could have and at the end to the car frame. The internal surfaces of the three fixed hollow beams (4 & 5) and the outside surfaces of the two movable hollow beams (7), could have been subjected to any treatment from the present technical level and could have been pre-lubricated accordingly in order to have small coefficient of friction, to eliminate resistance during the movement of the movable hollow beams (7).

At certain points, openings could be made for the purpose of installation and operation of the auxiliary mechanisms, the cable routing etc, or to obtain controlled deformation of the subsystem (16), during their design depending of the manufacturer.

At selected points of all hollow beams, fixed (4 & 5) and movable (7), there would be locking holes (11 , 12, B & K) of circular shape and diameter chosen by any manufacturer to be used by the securing mechanisms (9). For that purpose at the door's fixed hollow beam (4) there are two locking holes (11), also at the two ends, of the fixed hollow beams (5) of the vertical frame elements (2) one locking hole (12) and at the movable hollow beams (7) two locking holes (B & K) as close to their ends as possible.

With the above arrangement of positioning and specifications of construction of the fixed hollow beams (4 & 5), and movable hollow beams (7), the two movable hollow beams (7), are able to move inside the fixed hollow beams (4 & 5) of the subsystem (16) and can have only two certain positions.

The "off' position (FIG. 1 & 7), at which the movable hollow beams (7) are inside the door's (1) fixed hollow beam (4), locked at this position and the "on" position (FIG. 2 & 8), at which one part is inside the fixed hollow beams (4) of the door (1), and the rest is inside of the fixed hollow beams (5) of the vertical frame tubes (2), locked at this position.

D) Moving mechanisms (8) of the movable hollow beams (7) For the movement of the movable hollow beams (7), at the "on" and "off positions, two electromagnetic mechanisms (8) are used, one for each movable hollow beam

(7).

These mechanisms (8) are installed inside the door's (1), fixed hollow beam (4), with method derived from the existing technical level, are connected with the movable hollow beams (7), with the same way and are powered from the car's electrical supply through wiring.

E) Securing mechanisms (9) of the movable hollow beams (7)

The securing mechanisms (9) of the movable hollow beams (7), are four and are of the electromagnetic type, powered from the cars electric power supply using electrical cables and are positioned over the locking holes (11 & 12) of the fixed hollow beams (4 & 5), the method of their installation comes from the existing technical level.

Two of the securing mechanisms (9) are installed in the fixed hollow beam (4) of the car's doors (1) and one each mechanism (9) in the fixed hollow beam (5) of the vertical elements (2) of the car's frame.

The securing mechanisms (9), use locking pins (10) of circular cross section, as locking pins of equal diameter with that of the locking holes (11 , 12 , B & K), which are on the fixed hollow beams (4 & 5) and the movable hollow beams (7) when positioned inside the locking holes (11, 12, B & K), secure the movable hollow beams (7) at the two positions ("on" and "off') which can have.

For the sake of space and the shortening of moving distance the locking pins (10), can be inserted during installation as deep as the thickness of the wall of fixed hollow beams (4 & 5). F) Control Unit

As a control unit of the hollow beams systems (13), the car's computer is used, and is programmed in accordance with the method of the operation of the system to cover the needs of operation of the doors in normal conditions and in case of an accident, and to provide the suitable orders to the moving mechanisms (8) and securing mechanisms (9).

For its operation the control unit, is connected with cables to carry over the signals and receive data back with: a) The moving mechanisms (8) of the movable hollow beams (7), b) The securing mechanisms (9) of the movable hollow beams (7) and c) with sensors, which are installed to each door (1), in order to detect if the doors

(I) are at the closed position, with sensors which are connected internally and externally with the door (1) handles to open and close the doors, and with the sensors of the air bags of the car, because the receiving of this data is important for the smooth operation of the system.

For the improvement of the car's rigidity by using the car doors as part of the car's frame the above described system of five hollow beams (13), works as follows: The moving hollow beams (7) of each subsystem of hollow beams (16), in accordance with this invention could take two positions, which are "on" and "off".

In the "off' position (FIG. 1 & 7), the system of five hollow beams (13) is found, when the car's doors (1) are open.

Then the movable hollow beams (7) of the subsystems of hollow beams (16), are inside the fixed hollow beam (4) of the door (1) and secured at this position, by the locking pins (10) of the securing mechanisms (9) at the specified locking holes

(I I) of the door's fixed hollow beam (4) and the locking holes (B) of the movable hollow beams (7).

In this position the three fixed hollow beams (4 & 5) are not bridged to each other, the five hollow beams system (13), is not functioning and the frame's rigidity is not changed.

In the "on" position (FIG. 2 & 8) the five hollow beams (13) are, when the car doors

(1) are closed.

Then, the movable hollow beams (7), of the subsystems of the hollow beams (16), having moved from their previous position by the moving mechanisms (8), are half inside the door's fixed hollow beam (4) of the door (1) and half inside the fixed hollow beams (5) of the frame's vertical elements (2), secured in this position by the locking pins (10) of the securing mechanisms (9) at the specified locking holes (12 & B) and (11 & K) of the fixed hollow beams (4, 5, & 6) and the movable hollow beams (7).

In this position the system of the five hollow beams (13) is "operational", the two

movable hollow beams (7) bridge the three fixed hollow beams (4 & 5) and the five hollow beams (4, 5 & 7), secured (locked) between them, function as one beam which connects the vertical elements (2) of the frame to each other and turns each door (1) of the car, as a structural element of the frame, improving their rigidity.

To fulfill the possibility to operate and as a door (1) locking system in place of the existing door (1) locking mechanisms, the above described system of five hollow beams (13), operates as follows: When the door handle (inner or outer) is pulled out to open the door (1), the relevant sensor sends a signal to the control unit (the car's computer), which in turn sends a signal to the securing mechanisms (9), of the system of the five hollow beams (13) of the certain door (1) to unlock the movable hollow beams (7), from the "on" position, then the control unit sends a second signal to the moving mechanisms (8) to move to the "off" position inside the fixed hollow beam (4) of the door (1), and last, orders the securing mechanisms (9) to secure the movable hollow beams (7) at this position.

At this position the fixed hollow beams (4 & 5) are not bridged, the system is non operational (FIG. 1 & 7) and the doors (1) can open or stay open. During the closing of an open door (1), the sensor of the door will send a signal, that the door (1) is at the closing position, to the car's control unit which orders the securing mechanisms (9) of the five system hollow beams (13), of the specified door (1) to unlock the movable beams (7), from the "off' position, next sends a signal to the moving mechanisms (8) to move them to the "on" position inside the fixed hollow beams (5) of the frame's vertical pillars (2) and last orders the securing mechanisms (9) to lock securely the movable hollow beams (7), at this position.

For safety reasons, when the system is in the "on" position and a car crash happens, the car's control unit receives from the air bags sensor the relevant signal, sends a signal to de energize the system of five hollow beams (13) (as above) with a time delay device set by any individual car manufacturer, in relation to the collision time, in order the doors (1) to open without any problem.

Also, for safety reasons when the car is in motion the control unit may prohibit the de-activation of the five hollow beams system (13), keeping the doors (1) closed, even though somebody tries to open the door from outside or from inside, using the door handles.

At the second example of application of this invention (FIG. 3, 4, 9 & 10) an implementation of this invention is shown with a system of three hollow beams (14), which, for each door comprises from three subsystems of three hollow beams (17) like bellow.

A) Door's Frame (1) The doors frame (1) is designed in such a way as to be ready to accept the fixed hollow beams (4), of the three hollow beams subsystem (17), inside the frame and is strengthened with any way and method derived from the existing technical level, so it could be a robust and rigid element of the cars frame. B) Vertical (2) and horizontal (3) elements of the car's frame.

The vertical (2) and the horizontal (3) elements of the car's frame are designed in

such a way, derived from the existing technical level, in order to readily accept inside them the fixed hollow beams (5 & 6) and are strengthened in accordance with the existing technical level for the improvement of their rigidity. C) Hollow beams (4, 5, 6 & 7)

C1) Fixed hollow beams (4, 5 & 6 ) - Construction and installation The two fixed hollow beams (4 & 5 or 4 & 6) from each subsystem of three hollow beams (17) are square in cross section and equal in internal dimensions and apart from the length, of equal dimensions. They are installed at their position, as is described below in a way so that to be completely in line to each other and in to three dimensions in space.

The one fixed hollow beam (4), is positioned inside the door's frame (1), and installed by any convenient way in accordance with the existing technical level to the doors frame (1). It's length (4), is at least, exactly what is needed by design to be able to accept inside, the movable hollow beam (7), and it's one end is flush with the door's frame

(1).

The second fixed hollow beam (5 or 6) of each subsystem (17), is fixed permanently by any convenient way and method derived from the existing technical method, in a housing properly formed for this purpose, either to the corresponded vertical element (2), or the corresponded horizontal element (3) of the car frame so as to be structural element of the cars frame.

The fixed hollow beam (5 or 6) comes flush with the car frame in order to minimize any gaps (5 & 6) with the respective door's (1) fixed hollow beam (4) which will introduce fatigue to the tubes and reduction to their expected rigidity.

It's length is not specified but is dependable from the available for their installation space and the requirements for rigidity of each manufacturer.

The fixed hollow beams (4, 5 & 6), of each subsystem of three hollow beams (17) are compulsory open only at the end at which the one faces the other.

Movable hollow beam (7)-Construction and installation

The movable hollow beam (7) of each subsystem of three hollow beams (17) is of the same shape with the fixed beams (4 & 5 or 4 & 6) and are installed inside the fixed hollow beams (4), of the door's (1) in such away so that the one end to be flat with the face of the fixed hollow beams (5 or 6) of the vertical (2) or horizontal (3) elements of the frame.

The outer dimensions of the movable hollow beam (7), should be as close as possible with the inner dimensions of the fixed hollow beams (4 & 5 or 4 & 6), so that the clearance between the fixed hollow beams (4, 5 & 6), and the movable hollow beam (7), should be as small as possible almost touching each other as required to facilitate the movement and have little friction and no too large clearance which would create movement thus decreasing the rigidity and been a source of unwanted noise due to deflection and fatigue of the frame. The length of the movable hollow beam (7) is not specified but it should be at least as long as required by each manufacturer, so when the system is in the "on" position to be able to bridge the fixed hollow beams (4 & 5 or 4 & 6) as rigidly as possible of the subsystem of three hollow beams (17). C3) Common characteristics and operation of the fixed (4, 5 & 6) and movable hollow beam (7)

The common characteristics and the operation of the fixed hollow beams (4, 5 & 6), and the movable hollow beam (7) of each subsystem of three hollow beams (17), is quite the same with that defined at the first example, with the following exception: For the securing mechanism's operation (9) of each subsystem of three hollow beams (17), of the door's (1), fixed hollow beam (4), there is one locking hole (11), at the fixed hollow beam (5 or 6) of the vertical (2) or horizontal (3) elements of the frame one locking hole (12) and at the movable hollow beam (7) two locking holes (B & K). With the above arrangement of installation and the above specifications of construction and installation of the hollow beams (4, 5, 6 & 7), the movable hollow beam (7) of each subsystem (17), has the ability to move inside the fixed hollow beams (4 ,5 & 6) and can have two specific positions. The "off position (FIG. 3 & 9), at which the movable hollow beams (7) of each subsystem (17) is secured and completely inside the fixed hollow beam (4), of the door (1) and the "on" position (FIG. 4 & 10) at which part of the movable hollow beam (7), is inside the door's (1) fixed hollow beam (4) and part of it, is inside the fixed hollow beam (5), of the vertical elements (2) of the car's frame or inside the fixed hollow beam (6) of the horizontal elements (3), also secured in this position.

D) Moving mechanisms (8) of the movable hollow beams (7) For the movement of the movable hollow beam (7), of each subsystem of three hollow beams (17) in the "on" and "off' positions an electromagnetic mechanism (8) is used.

This moving mechanism (8) is fitted inside the door's (1) fixed hollow beam (4), in a way and method derived from the existing technical level and is powered from the cars electrical system. E) Securing mechanisms (9) of the movable hollow beams (7).

To secure the movable hollow beam (7) of each subsystem of three hollow beams (17) in the "on" and "off" positions two securing mechanisms (9) are used of the electromagnetic type and are powered from the car's electrical power system using electrical cables and are positioned in the locking holes of the of the fixed hollow beams (4, 5 & 6), installed in to them with method and way derived from the existing technical level.

They use locking pins (10) of round sectional area, ready to be fitted inside the locking holes (11 , 12, B & K) which are in the hollow beams (4, 5, 6 & 7) which when they are moved in and out of the respective locking holes, they lock and unlock the movable hollow beams (7) at the two positions it can have.

To save space and to minimize the distance of movement the locking pins (10), are inserted so deep as to cover the thickness of the wall of the fixed hollow beams (4, 5 & 6). F) Control unit

As a control unit of the whole system the car's computer is used having the same characteristics and specifications of its operation like the ones of the previous example. For the improvement of rigidity of the car's frame through the use of the doors as an structural element of the car's frame the above described system of three

hollow beams (14), functions as below:

The movable hollow beam (7), of each subsystem of three hollow beams (17), in accordance with the invention, can have only two positions, which correspond to the "on" (locked) position and "off' (unlocked) position respectively.

In the "off' position (FIG. 3 and 9) the system of three hollow beams (14), is when the car's door's (1), are open.

Then the movable hollow beams (7) of the three hollow beams subsystem (17), are entirely inside the door's (1) fixed hollow beams (4), secured in this position by the locking pins (10) of the securing mechanisms (9), inside the locking holes (11) of the door's (1) fixed hollow beams (4) and the locking holes (B) of the movable hollow beams (7).

In this position, the fixed hollow beam (4) of each subsystem of three hollow beams (17), of the door (1), is not bridged with the fixed hollow beam (5 or 6) of the vertical (2) or horizontal (3) elements of the frame, the system of three hollow beams (14) is non operational and the rigidity is not altered.

In the "on" position (FIG. 4 & 10) the system of the three hollow beams (14) is when the doors (1) of the car are closed.

Then the movable hollow beam (7), of each subsystem of three hollow beams (17), having been moved from their previous position by the moving mechanism (8), is found partially inside the fixed hollow beam (4) of the door (1) and partially inside the fixed hollow beam (5) of the vertical (2) or inside the fixed hollow beam (6) of the horizontal (3) elements of the frame, secured at this position, by the locking pins (10) of the securing mechanisms (9), inside the locking holes (12 & B) and (11 & K) of the fixed hollow beams (4, 5 & 6) and the movable hollow beam

(7).

In this position the system of three hollow beams (14) is operational, the movable hollow beams (7) bridges the fixed hollow beams (4) of the door (1) with the fixed hollow beams (5 & 6) of the vertical (2) or the horizontal (3) elements of the frame and the three hollow beams ( 4, 5 & 7 or 4, 6 & 7) of each subsystem of three hollow beams (17), secured (locked) between them, operate as one which bridges the door (1) with the vertical (2) and the horizontal (3) elements of the frame, intergrading each door (1) of the car as structural element of the frame , thus improving it's rigidity.

At the third example (FIG. 5, 6, 11 & 12) of the implementation of this invention an application of this invention is presented with a combined system of hollow beams (15) which, for each door (1), comprises from one subsystem of five hollow beams (16) and one subsystem of three hollow beams (17) and one control unit of the hollow beams (16 & 17) subsystems. • ^■ *

The characteristics of construction, installation and operation of subsystems of hollow beams (16 & 17), are the same with the examples (1) and (2) respectively. The FIG. 5 & 11 show the combined system of hollow beams (15) in the "off" position and the FIG. 6 & 12 shows it at the "on" position.