DRIVE FOR PLASTIC COVER FOIL

Abstract: A building structure consisting of a framework of posts (1) and beams (2) of profile material which is covered on the outside with sheet-like material (10) such as plastic foil, wherein on at least the roof part the foil is fixed with a longitudinal edge to a longitudinal beam (5) connected to the framework, wherein a second longitudinal beam (15) is fixed to the parallel opposite longitudinal edge of the foil and is driven rotatably on the axis thereof such that the second beam winds itself into respectively out of the foil, and the drive is formed by a reversible motor (24) which is provided with a resistance-sensitive sensor element which controls the power supply of the motor for switch-off thereof, so that the tension in the foil is always adjusted optimally.

Description: DRIVE FOR PLASTIC COVER FOIL The invention relates to a building structure consisting of a framework of posts and beams of profile material which is covered on the outside with sheet-like material such as plastic foil, wherein on at least the roof part the foil is fixed with a longitudinal edge to a longitudinal beam connected to the framework, wherein a second longitudinal beam is fixed to the parallel opposite longitudinal edge of the foil and is driven rotatably on the axis thereof such that the second beam winds itself into respectively out of the foil and wherein the drive is formed by a reversible motor. Such a construction has been described earlier in a previous patent of applicant, which embodiment was based on the drive motor of the winding system cutting out at a determined number of revolutions. Since the roof consists of a foil, usually plastic foil, this roof is temperature-sensitive. It may therefore be the case that when the prescribed number of revolutions has been reached the foil does not have the correct tension. If too few revolutions are made -the foil is too slack; with too many revolutions the foil tears or the motor burns out . In such a construction the motor must therefore be very precisely adjusted and regularly readjusted. The foil will stretch or shrink due to hot or cold weather, whereby once the foil has been unrolled it will never have the optimum tension. The invention has for its object to improve the drive of the building structure as described in the preamble and proposes to this end to provide the drive with a resistance-sensitive sensor element which controls the power supply of the motor for switch-off thereof. If use is made of an electric motor, it is recommended to incorporate an electrical resistance in the power supply which detects when the current respectively voltage in the power supply increases and the control signal of which can switch off the power supply. According to a further embodiment the electric motor can drive the second longitudinal beam via a self- locking transmission system. If the power supply of the electric motor fails, the system then remains in self- locked position. The resistance measurement in the case of electrical driving can also take place thermally αr in any other appropriate manner, for instance electronically. According to another embodiment of the invention the motor power can also be limited by a mechanical torque limiter. The invention is further elucidated in the figure description of an embodiment hereinbelow. In the drawing : figure 1 shows a perspective top view of a building structure according to the invention; figure 2 shows a perspective view along arrow II of a detail of the ridge construction of a part of the framework of figure 1; figure 3 is a perspective view along arrow III in figure 1 of a part of the drive of the second longitudinal beam with foil wound thereon; figure 4 is a perspective view along arrow IV in which the winding and tensioning function of the second beam is further elucidated; figure 5 is a perspective view, corresponding with figure 1 of a second embodiment of the building structure according to the invention; figure 6 is a perspective view of a detail of the structure in figure 5 on an enlarged scale; figure 7 is a side view of the upper beam suitable to be used in a building structure according to figure 5, near figure 8, a perspective view of a part of the motor drive for the foil; figure 9 is a cross-section according to arrow IX- IX in figure V; figure 10 is a schematic view of a torque-limiting device used in the drive of figure 8. In the description the same numeral references are used for the same parts of the building and drive means. The building structure shown in figure 1 consists of a framework or assembly of posts 1, longitudinal and cross beams 2 respectively 3, and curved cross beams 4 on the highest point of which is fixed a longitudinal beam 5. All these components are formed from profile material or compound profile material . If desired, cross braces can be arranged which can be formed by rods 6, on the left in figure 1, or tensioning wires 7 between the curved cross beams 4. As shown, the outside of the framework is covered with plastic foil, this being indicated with 10 along the side panels of the framework and 11 on the roof part . The method of fixing and rolling up the cover foil 11 for the roof part is further explained with reference to figures 1-4. Foil 11 is fixedly attached with a longitudinal edge 12 to the roof longitudinal beam 5, see figure 2, which beam consists here of two profiles 13 held at a mutual distance, the lower flange of which is mounted on curved cross beam 4. Longitudinal edge 12 is clamped fixedly against the long side of profile 13 by means of a clamping strip 14. Foil material 11 has a length which corresponds with a part of or the whole length of the building structure to be spanned and a width at least corresponding with half the curved cross beam of the framework. The free edge strip of foil 11 parallel to the longitudinal edge 12 which in the covering situation is situated close to the lower end of curved cross beams 4, is fixed to a second longitudinal beam in the form of a rod or pipe 15, see also figure 3, which is driven rotatably on the axis thereof, this being further elucidated below, such that the rod can wind itself into respectively out of foil 11. It is thus possible to roll up half the span of cross beam 4 from the underside as far as the first longitudinal beam 5 and to unroll it again in reverse direction in order to cover the framework. Reference is made for the drive to figure 3 which shows that the foil width 11 is interrupted locally, wherein two cross beams 4 are arranged lying very close to each other. In the space between cross beams 4 the free second longitudinal beam 15 is embodied with a chain wheel 20 around which is trained a chain 21. This leads to a second chain wheel 22 on the driven shaft 23 of an electric motor 24. This latter is mounted in a sub-frame 25 in the form of a U-shaped bracket to which a reaction rod 26 is fixed. The reaction rod is connected via a slide connection 27 to a longitudinal beam 2 of the framework. Various aspects are embodied such that reaction rod 26 can shift transversely of longitudinal beam 2 when sub-frame 25 moves along the underside of the curved cross beam 4. This movement is effected by suitable energizing of motor 24 in the one or other rotation direction, whereby in chain transmission 21 the wheel 20, and thus rod 15, are set into rotation. Depending on the rotation direction the rod will therefore wind itself into respectively out of foil width 11 in the direction of arrow PI, see figure 3. The chosen construction enables the motor with drive to be situated under foil width 3, whereby the construction is protected against weather influences. It is noted that the gap between the two mutually adjacent cross beams 4 can be covered with a roof covering (not shown) . Other drives are possible within the scope of the invention, for instance a central motor which is connected to the second longitudinal beam 5 via a cable, chain system or the like in order to drive the beam in the one or other rotation direction. In order to draw the foil tautly over the curved cross beams or trusses 4, it is recommended to embody the bottom edge construction of the roof covering close to the intermediate channel profiles 30 such that the bottom edge projects over channel profile 30, see figure 4. This projection is realized here by providing channel profile 30 on the top with a bracket 31, on the free end 32 of which is mounted a tube 33. The lower ends of trusses 4 end on this tube 33. During unwinding of the second longitudinal beam out of foil 11 in the direction of arrow P2 , tube 15 will, when foil 11 has a sufficient width, drop downward past tube 33 into the position indicated with A in figure 4. With continued rotation of longitudinal beam 15 in the same direction P2 the tube will wind itself into the other side of the foil and finally become clamped under the longitudinal tube 33 in the position indicated with B in figure 4. In this manner the foil strip 11 is pulled taut over the fixed longitudinal tube 33 and in normal conditions the foil will come to lie firmly and without play on cross beams 4. In abnormal conditions, for instance a higher temperature, the foil could develop more play, and this is prevented by providing electric motor 24 with the resistance sensor proposed according to the invention as discussed above. Motor 24 is rotated so far in the direction of arrow P2 that the foil is pulled taut over truss 4, whereafter the drive resistance increases such that either the temperature of the motor rises or the voltage respectively the current in the power supply increases, which can be detected by suitable sensors which generate a signal to switch off the motor. The motor can be provided with a self-locking transmission whereby the correct tension remains in the foil, or other locking systems are used. Release of the foil and winding up thereof takes place by driving longitudinal beam 15 in reverse direction, whereby first the position A is reached and winding-up then begins for opening of the roof part of the building structure. Motor 24 is of random nature within the scope of the invention and can also be a hydraulic motor. Turning now to figure 5, the roof structure of said further embodiment is provided with a fixed cover extending over the lower part provided with the plastic foil cover. Also here, the foil is fixed to a second longitudinal beam in the form of a rod or pipe 15, being driven by an electric motor 24 supported on a rotatable guide rod 26 which can pivot at 27 with respect to the cross beam structure 3. The electric motor is not the tube-motor type as depicted in figure 1, but a normal 3 -phase motor, which is provided with a transmission 40, driving a chain transmission taken up in a closed housing 42. The chain transmission drives the longitudinal pipe 15. The electric motor 24 is reversible, such that the rod can wind itself into respectively out of foil 11 dependent on the driving direction. Also here the transmission 40 is self-locking. The other side of the motor housing 24 is provided with a torque limiter, depicted in figure 10. The square rod 50 is clamped in between rockable plates 51, 52, pivotable about pivot, the axis of which is parallel to that of the square rod 50. The plates are biased by springs 54, such that the plates 51, 52 are fixedly clamped with a certain force to the flat sides of the square rod 50. When the torque of the motor 25 will exceed a certain rate, the square rod 50 will turn and spread the plates 51, 52 against the force of the biasing springs. When spreading the plates an end switch 54, 55 will be actuated so giving a signal to the drive of the motor to cut off the electric power for the motor. This will lead to a complete automatic switch off of the drive, maintaining the foil under a certain tension to have it covered closely over the cross beams 4. Furthermore, the gutter structure 30 is amended, now having a flange structure on top of the side walls of the gutter 30, said flenges are profiled such that the upper rim is extending inwardly. That rim 60 will be used to hold the rod or pipe for the foil when the foil is in the closing position over the full width of the structure in figure 5. It is possible to cover the building according to figure 5, by a second fixed cover, made of fixed plastic plates 61, which are supported by the cross beams 4. The upper cover 62, formed by fixed plates of plastic material, is suspended by the upper cross beams 4'. In this embodiment, the foil 11 can be used as a sun shade and will be stretched over the lower opaque cover .61 as depicted in figure 6. Due to the double roof top a good isolation is obtained, whereas the foil 11 can be used for a temperature control leaving more or the less sunshine into the building. In order to make it possible to swing the drive motor 24 on top of the reaction rod 26 from the open to the closed position, the fixed cover 61 is provided with a brush means 63, the chain drive of the drive motor 24 can be passed through, see also figure 8 and 9. Finally it is noted that the top beam 5 in between the lower and upper cross beams 4, 4' in figure 7, is in principal an I-beam, the lower part being provided with channels opening sidewardly in order to take up the fixed edge of the foil 11. The channels 70, 71 receiving said edge of foil 11, can be closed partly by L-shaped beams, the smaller leg pointing into the channel and keeping the thickened edge of the foil 11 in the channels 71, 72.

Claims: CLAIMS 1. Building structure consisting of a framework of posts and beams of profile material which is covered on the outside with sheet-like material such as plastic foil, wherein on at least the roof part the foil is fixed with a longitudinal edge to a longitudinal beam connected to the framework, wherein a second longitudinal beam is fixed to the parallel opposite longitudinal edge of the foil and is driven rotatably on the axis thereof such that the second beam winds itself into respectively out of the foil and wherein the drive is formed by a reversible motor, characterized in that the drive is provided with a resistance-sensitive sensor element which controls the power supply of the motor for switch-off thereof. 2. Building structure as claimed in claim 1, characterized in that the motor is provided with a transmission which is self-locking. 3. Building structure as claimed in claims 1 and 2, characterized in that a resistance sensor or temperature sensor is incorporated in the power supply circuit of the drive embodied as electric motor. 4. Building structure as claimed in claim 1, characterized in that the drive comprises a mechanical torque limiter. *****

Inventors: VERMEULEN ARNOLDUS HENRICUS AN, VERMEULEN, ARNOLDUS, HENRICUS, ANTONIUS
Applicants: ROVERO SYSTEMS B V, VERMEULEN ARNOLDUS HENRICUS AN, ROVERO SYSTEMS B.V., VERMEULEN, ARNOLDUS, HENRICUS, ANTONIUS
Application year: 2000
Main classification: E04H3
IPC codes: A01G9, E04B1, E04B7, E04H15