Patent Publication Number: US-6910233-B2

Title: Elongated roller shutter profile made of plastic or metal for swimming pool covers

Description:
FIELD OF THE INVENTION 
     The invention relates to an elongated roller shutter profile made of plastic or metal for swimming pool covers, comprising at least one water-proof closure with which at least one hollow chamber extending in the longitudinal direction of the roller shutter profile can be closed off on a face side of the roller shutter profile, with the closure comprising a cap which is at least partly insertable into the hollow chamber from the face side, comprises a piston plate disposed at a distance to the cap within the respective hollow chamber and a sealing medium extending between the cap and the piston plate. 
     BACKGROUND INFORMATION 
     Such a roller shutter profile is known for example from EP 0 225 862 A1 as well as EP 0 732 469 A1. The known roller shutter profiles are used in particular in the form of extruded plastic profiles for swimming pool covers. Since the swimming pool covers lay on the water surface and should swim on the water surface due to the air-filled hollow chambers, it is important that the roller shutter profiles are occluded at their ends. Since such roller shutter profiles are used in the outside, special attention must be given to the fact that both the material of the roller shutter profile per se as well as the material of the closure are weatherproof, i.e. it must be especially resistant to UV radiation and larger temperature fluctuations. It is not permitted that the materials become brittle during the service life of such covers or will warp as a result of temperature fluctuations, which would lead to leakages. 
     In the roller shutter profiles as are known from EP 0 225 862 A1 as well as EP 0 732 469 A1 the piston plates are each connected via a piston-rod-like shaft with the cap. The cap comprises a stopper section which is adjusted to the cross section of the respective hollow chamber and is introduced into the same. The cross section of the piston plate is similarly adjusted to the cross section of the hollow chamber. The impermeability is produced in such a way that the intermediate space between the piston plate and the stopper section is filled at first with sealing medium which is free-flowing at first, which sealing medium is introduced through an opening in the stopper section of the cap from the outside by means of a suitable filling means. The sealing medium which is based on a plastic material shows favorable adhesive properties which produce a permanent connection of the same with the walls of the hollow chamber and cures after a certain period of time. In this way a permanent closure of the roller shutter profile can be achieved which cannot be reversed. Whereas each hollow chamber is associated with its own supply opening and a venting or overflow opening adjacent thereto in the roller shutter profiles as known from EP 0 225 862 A1, the further development as known from EP 0 732 469 A1 is that adjacent hollow chambers can be closed off by way of a single filling process. For this purpose the liquid scaling medium flows at first through a supply opening into the first hollow chamber in order to then pass through an overflow duct into the adjacent hollow chamber and to move from there to further adjacent hollow chambers, if any. In the last hollow chambers which are thus connected in series there is a venting or overflow opening in the associated stopper section of the cap, so that the filling process can be ended at the time when the sealing medium emerges from said opening. 
     Even though it was possible to achieve a reduction of the working time in the production of waterproof closures in the further development as described in EP 0 732 469 B1, the use of such free-flowing and curing sealing mediums is generally problematic. One disadvantage is that the closures cannot be mechanically loaded directly after the filling with the sealing medium because it reaches the required hardness only after a certain period of time, i.e. it is capable of withstanding the action of a force. Moreover, the filling of the sealing medium into the intermediate space between the piston plate and the sealing cap can only occur with a certain conveyance rate, so that in practice there is a required time per hollow chamber to be filled of several seconds. A further disadvantage is that interruptions in the filling process lead to a curing of the sealing medium also in the filling apparatus, so that time-consuming cleaning work is necessary prior to resuming the filling. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of further developing a closure for a roller shutter profile for swimming pool covers in such a way that on the one hand the time required in producing the impermeable closure is reduced and on the other hand the removability of the sealing is enabled. 
     Based on the roller shutter profile of the kind mentioned above this object is achieved in accordance with the invention in such a way that the sealing medium is a sealing body made of an elastic and/or plastic material which based on a mounting state in which it can be introduced into the hollow chamber it can be brought into a sealing state by clamping between the piston plate and the cap in which it is expanded in a direction perpendicular to the longitudinal direction of the hollow chamber, so that it rests in a circumferentially tight manner on the walls delimiting the hollow space. 
     The closure in accordance with the invention thus differs at first from the state of the art in that a free-flowing sealing medium is no longer used, but a sealing body which although it has elastic and/or plastic properties is substantially dimensionally stable without any external action of a force. The sealing effect relative to the walls of the hollow chamber is achieved in accordance with the invention in such a way that a pressure is exerted on the sealing body on both sides in the direction of the longitudinal direction of the hollow chamber, so that a deformation of the same consequently occurs which produces an increase in the dimensions of the sealing body in the direction perpendicular to the longitudinal direction of the hollow chamber. This extension of the roller shutter profile produces a circumferential contact of the same on the walls of the hollow chamber, thus producing the desired sealing effect. 
     The use of a sealing medium is advantageously no longer required which changes its properties after the filling into the intermediate space between the piston plate and the sealing cap in such a way that it changes from a free-flowing state to a sufficiently solid one. A chemical or other change of material after fitting the roller shutter profile with the closure is no longer required according to the teachings in accordance with the invention. Ageing problems as may occur during an extended storage of the liquid sealing medium according to the state of the art need not be anticipated any longer in accordance with the invention. When using suitable materials the invention also allows a reversibility of the closure in the sense that after removing the clamping of the sealing body between the piston plate and the sealing cap there is a detachment from the walls of the roller shutter profiles due to a reverse formation of the sealing body, so that the closure can be removed again in its entirety. When using a sealing body which deforms in a exclusively plastic way and which may come with adhesion properties in conjunction with the walls of the hollow chamber, the property of reversibility is obviously not given because a reverse formation and detachment of the sealing body from the walls could hardly be achieved in this case. 
     It is principally imaginable that the piston plate rests with a projection on the walls of the hollow chamber which prevents a further displacement of the same into the interior of the hollow chamber and that a clamping between the piston plate and the cap is achieved in such a way that the cap also latches behind a projection for example. The distance between the piston plate and cap in this sealing state of the closure is dimensioned in such a way that the shortening of the sealing body in the axial direction which is thus obtained produces a sufficient radial expansion of the same in order to achieve producing contact with the walls with a sufficient amount of pre-tensioning. 
     It is provided for according to an especially preferred embodiment of the invention that a connecting element is provided which extends between the cap and the piston plate and is under tensile stress at least during the transfer of the sealing body into the sealing state. In this case it is not necessary to provide a support both for the piston plate as well as the cap on the walls of the roller shutter profile, which is especially advantageous in the case of extruded profiles because such projections (e.g. abutments) are not easy to make. Under certain circumstances it is sufficient to produce the tensile stress only once or for a certain period of time, namely when the sealing body consists of a plastic material which develops a strong adhesive force in conjunction with the walls of the hollow chamber. In this case it is not necessary to expect a reverse formation of the sealing body even after removing the tensile stress on the connecting element, i.e. a pressure relief of the sealing body, as a result of the elasticity properties which are manifested either in a weak way or not at all, so that the circumferential adherence to the walls will be maintained even without any further action of force on the sealing body. 
     In the case of roller shutter profiles with several hollow chambers which extend parallel with respect to each other and are separated from each other by a separating wall extending in the longitudinal direction of the roller shutter profile, the sealing process can be completed in an especially rational fashion when the closure comprises a cap which can be introduced into several hollow chambers simultaneously and which is associated with a number of sealing bodies and piston plates which corresponds to the number of hollow chambers. 
     In accordance with a further embodiment of the roller shutter profile in accordance with the invention, the connecting element penetrates the sealing body and the cap and is movable in the longitudinal direction of the hollow chamber relative to the sealing body and the cap. The penetration of the sealing body allows a reliable sealing on its circumference, i.e. a direct contact of the elastic or plastic material of the sealing body on the ambient chamber walls. 
     A further development of the invention is also that the connecting element is a screw whose thread cooperates with the piston plate. Preferably, the screw also penetrates the cap and rests with its screw head thereon on the outside. A metallic nut can be formed into the piston plate when it is produced by way of injection-molding, which metallic nut cooperates with the machine tap of the screw. As an alternative it is also possible to shape merely a pocket bore into the piston plate into which a screw with a self-cutting thread is turned. 
     An alternative embodiment of the roller shutter profile in accordance with the invention is that the rod-like connecting element is connected in an integral manner with the piston plate and comprises barbs on its surface which cooperate with a detent pawl which is arranged in the cap. In this type of connection between piston plate and cap which works according to the principle of cable binders, the process of producing the pre-tensioning on the sealing body is strongly simplified. A free end of the connecting element which projects from the cap merely needs to be pulled in the direction out of the hollow chamber with a defined force. The pre-tensioning on the sealing body is maintained permanently by the locking function of the barbs after removing the external tensile force. A reversible removal of the sealing effect is not possible in this kind of locking. An unlatching possibility for the detent pawl is possible in principle, however. 
     There is a further development of the roller shutter profile in the respect that the piston plate and/or the cap are elevated in a conical manner on the face-side contact surface facing the sealing body and the sealing body per se is sunk in a complementary conical manner on at least one of its two opposite face-side contact surfaces which correspond to the contact surfaces of the piston plate and/or the cap. The cooperation of the conical surface with the conical surface which is configured in a complementary fashion leads to an improved translation of the axial tension into a radially directed expansion of the sealing body in the case of the axial clamping of cap and sealing body or of piston plate and sealing body. The contact surfaces which are cone-shaped/conical in a complementary fashion can be attached either only to one side to the sealing body and the respectively adjacent component or also to both sides of the sealing body. 
     It is moreover possible to provide the sealing body with a gas filling in a hollow chamber which is inherently closed off in an annular way and is externally sealed off. In the case of an axial pressing of the sealing body between the piston plate and the cap, the compression of the hollow chamber leads to a radial expansion of the same due to its impermeability. In conjunction with the reduced wall thicknesses of the sealing body in the region between the hollow chamber and the wall of the hollow chamber of the roller shutter profile, the outside jacket of the sealing body sits close to the inside jacket of the hollow chamber in an improved manner. 
     It finally also lies within the scope of the present invention to provide a closure for sealing in a water-proof manner an elongated roller shutter profile made of plastic or metal, with the closure having the features and properties as described above. Such closures can be used for example as spare parts for roller shutter profiles which are already present or as independently marketable merchandise. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The closure of a roller shutter profile in accordance with the invention is explained below by reference to several embodiments shown in the drawings, wherein: 
         FIG. 1  shows a top view of a closure of a roller shutter profile represented in sections; 
         FIG. 2  shows a side view of the closure according to  FIG. 1 ; 
         FIG. 3  shows a rear view of the closure according to  FIG. 1 ; 
         FIG. 4  shows a front side of the closure according to  FIG. 1 ; 
         FIG. 5  shows an alternative closure with connecting elements in the form of machine screws; 
         FIG. 6  shows a further alternative closure with connecting elements in the form of screws with self-cutting threads; 
         FIG. 7  shows a further alternative closure with cone-shaped/conical contact surfaces between sealing body and piston plate as well as sealing body and cap, and 
         FIG. 8  shows a further alternative closure with a sealing body with an annular hollow chamber. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE OF THE INVENTION 
     A roller shutter profile  1  which is shown in  FIGS. 1  to  4  in sections in a longitudinal sectional view consists of a thermoplastic material (e.g. PVC) and is produced by way of extrusion. The roller shutter profile  1  comprises two hollow chambers  3   a  and  3   b  which extend in its longitudinal direction  2  and are delimited by two longitudinal walls  4  and  5  as well as a separating wall  6  extending between the hollow chambers  3   a  and  3   b . Adjacent to the longitudinal wall  5  there is a further chamber  7  which is open on its longitudinal side and in which engages a bridge-like hook strip  8  of an adjacent roller shutter profile, thus producing a flexible connection between two or a plurality of roller shutters  1 . A roller shutter armor is formed in this way from a plurality of extruded profile elements which extend parallel with respect to each other, e.g. for a swimming pool cover which can be wound up or off. 
     From a face side  9  of the roller shutter profile  1 , the same is sealed off in a water-proof manner by means of a closure  10 . The closure  10  consists of a cap  11 , two piston plates  12   a  and  12   b , two sealing bodies  13   a  and  13   b  as well as two connecting elements  14   a  and  14   b . Cap  11  comprises a plate  15 , a rounded sliding strip  16  which projects therefrom in a rectangular manner as well as two stopper sections  17   a  and  17   b  which are adjusted to the cross section of the hollow chambers  3   a  and  3   b  like the piston plates  12   a  and  12   b  and the sealing bodies  13   a  and  13   b . The stopper sections  17   a  and  17   b  penetrate with their entire length into the hollow chambers  3   a  and  3   b , whereas the plate  15  rests on the face sides of the roller shutter profile  1 . 
     The connecting elements  14   a  and  14   b  are integrally connected with the respective piston plates  12   a  and  12   b  and consist of nylon. The upper side of the flexible rod-shaped connecting elements  14   a  and  14   b  is provided with barbs  18 . The connecting elements  14   a  and  14   b  penetrate the sealing bodies  13   a  and  13   b  in breakthroughs (not shown) which with respect to their cross section are adjusted to the cross section of the connecting elements  14   a  and  14   b . Similarly, said connecting elements  14   a  and  14   b  also penetrate the cap  11  in the region of the stopper sections  17   a  and  17   b  as well as the plate  15  in adjusted breakthroughs  19   a  and  19   b  (cf. FIG.  3 ). Detent pawls  20   a  and  20   b  are provided within the plate  15  on the upper side of the breakthroughs  19   a  and  19   b , which detent pawls cooperate with the barbs  18  of the connecting elements  14   a  and  14   b  and prevent a movement of the same in the direction of arrow  21 . 
     The sealing bodies  13   a  and  13   b  consist of a rubber-elastic plastic material of a low hardness. The material is UV-resistant and can resist temperatures of up to at least 100° C. because due to insolation on the upper and lower walls  22  and  23  of the roller shutter profile far from inconsiderable temperatures can occur in the region of the closure  10 . Suitable materials are silicone elastomers, fluorine elastomers, fluorosilicone elastomers or blending elastomers from the unvulcanized rubbers of the aforementioned elastomers or polyurethanes. 
       FIGS. 1 and 2  show the closure  10  in its mounting state. The cross section of the sealing bodies  13   a  and  13   b  which are free from the external forces is adjusted to the hollow chambers  3   a  and  3   b , so that the pre-mounted closure  10  can be introduced with all its parts (as shown in  FIGS. 1 and 2 ) from the face-side end of the roller shutter profile  1 . The transfer of the closure  10  or the sealing body  13   a  and  13   b  to the sealing state (not shown in the drawing) is performed in a simple manner, such that the connecting elements  14   a  and  14   b  are pulled out of the hollow chambers  3   a  and  3   b  against the direction of the arrow  21 , with the cap  11  being held in its contact position on the face side  9  of the roller shutter profile  1 . By pulling out the connecting elements  14   a  and  14   b , the piston plates  12   a  and  12   b  are pushed against the sealing bodies  13   a  and  13   b  and these two components then jointly against the stopper sections  17   a  and  17   b  of cap  11 . Once the tensile force on the connecting elements  14   a  and  14   b  is further increased after reducing the intermediate spaces  24   a  and  24   b  and  25   a  and  25   b  to zero, there will be an elastic deformation of the same or, depending on the chosen material of the sealing bodies  13   a  and  13   b , even a plastic deformation of the same. As a result of the pressure exerted in the longitudinal direction  2  of the hollow chambers  3   a  and  3   b , the sealing bodies  13   a  and  13   b  will extend in the direction perpendicular thereto, so that as a result of the increase in the cross section of the sealing bodies  13   a  and  13   b  there will be a circumferentially tight contact of the same on the longitudinal walls  4  and  5 , the separating wall  6  as well as the upper and lower wall  22  and  23  of the roller shutter profile  1 . As a result of the compressive strain on the sealing bodies  13   a  and  13   b  produced by the tensile stress in the connecting elements  14   a  and  14   b , there will also be a circumferentially tight contact of the mutually facing plane face sides of the contact surfaces of the piston plates  12   a  and  12   b  and the sealing bodies  13   a  and  13   b  as well as the latter and the stopper sections  17   a  and  17   b  of the cap  11 . It is prevented in this way that liquid can reach along the connecting elements  14   a  and  14   b  through the breakthroughs  19   a  and  19   b  into the stopper sections  17   a  and  17   b  and through the breakthroughs into the sealing bodies  13   a  and  13   b  into the interior of the hollow chambers  3   a  and  3   b.    
     As shown in  FIG. 3 , the cross-sectional shape of the chambers  3   a  and  3   b , and thus also of the stopper sections  17   a  and  17   b , the sealing bodies  13   a  and  13   b , and the piston plates  12   a  and  12   b , can be a polygon having plural straight sides or edges. For example, the chamber  3   b  has a four-sided rectangular shape, while the chamber  3   a  has a six-sided complex polygon shape. 
     The closure  10 ′ as shown in  FIG. 5  differs from that shown in  FIGS. 1  to  4  merely in the respect that the connecting elements  14   a ′ and  14   b ′ are configured as machine screws made of stainless special steel with a recessed countersunk head screw  26 . The ends of the connecting elements  14   a ′ and  14   b ′ which are averted from the cap  11 ′ cooperate with nuts  27   a  and  27   b  which are also made of stainless special steel. Said nuts  27   a  and  27   b  are simultaneously injected over when the piston plates  12   a ′ and  12   b ′ are produced by means of injection molding. The reduction in the distance between the piston plates  12   a ′ and  12   b ′, the sealing bodies  13   a ′ and  13   b ′ and the stopper sections  17   a ′ and  17   b ′ of the cap  11 ′ occurs by turning the screws. The radial expansion which occurs by pressing the sealing bodies  13   a ′ and  13   b ′ and the thus achieved sealing can be removed again by a respective reverse turning of the screws. Consequently, the hollow chambers of the profiles which are closed off with such closures  10 ′ can be accessed again at any time without destroying the sealing and having to produce the same with spare parts again. 
       FIG. 6  shows a further alternative closure  10 ″ in which the connecting elements  14   a ″ and  14   b ″ are configured as screws with a self-cutting thread. The ends the connecting elements  14   a ″ and  14   b ″ which are averted from the cap  11 ″ engage in pocket bores  28   a  and  28   b  in the piston plates  12   a ″ and  12   b ″. The diameters of the pocket bores  28   a  and  28   b  which are shaped by means of injection-molding are smaller than the diameters of the screws. Whereas the thread extends over the entire shaft length of the screw in the connecting element  14   a ″, the shaft of the connecting element  14   b ″ is subdivided into a front part with a thread and a rear part without such a thread. The piston plate  12   b ″ comprises a contact part  29   b  which faces the sealing body  13   b ″ and whose cross section is adjusted to the cross section of the hollow chamber  3   b , and comprises rear pin part  30   b  whose cross section is reduced with respect to the same. 
     The mounting of the connecting elements  14   a ′ and  14   b ′,  14   a ″ and  14   b ″ which are arranged as screws preferably occurs by means of torque-controlled tightening tools in order to produce a defined axial pre-tensioning on the sealing bodies  13   a ′ and  13   b ′,  13   a ″ and  13   b ″. The mounting of the closure  10  according to  FIGS. 1  to  4  occurs preferably by means of a tool in the manner of tongs which produces at first a pretension on the rod-shaped connecting elements  14   a  and  14   b  and, when reaching a certain tensile force in analogy to the function of blind riveting tongs, causes a cut-off or notching and detachment of the projecting end of the connecting elements  14   a  and  14   b . They can also be provided at the respective position with a defined break-off point which responds when a certain tensile stress is reached. 
       FIG. 7  shows a closure  30  in which the sealing body  33  which is penetrated by a screw has a shape which is provided at the two mutually opposite face-side contact surfaces  35 ′ and  35 ″ with a conical hollow. Both the piston plate  32  and the cap  31  have conical elevations in the region of the contact surfaces  35 ′ and  35 ″, which elevations are complementary to the hollows in the sealing body  33 . The inclined surfaces which slide on each other during the axial pressing produce an especially favorable translation of the axial pre-tensioning into a radial expansion of the sealing body  33 . 
       FIG. 8  finally shows a further embodiment of a closure  40  in which the piston plate  42  and the cap  41  and the substantially cylindrical sealing body  43  which is provided with a central pass-through bore for the screw are each provided with plane face-side contact surfaces  45 ′ and  45 ″. Differing from the sealing bodies as explained above, the sealing body  43  according to  FIG. 8  comprises an annular, inherently closed and outwardly sealed hollow chamber  46 . It has the shape of a torus with an oval cross section. The wall thickness of the sealing body  43  in the region between the hollow body  46  and the wall of the roller shutter profile is smaller than the wall between the hollow chamber  46  and the pass-through bore for the screw. The comparatively thin outside wall produces a high amount of flexibility in the sealing area, so that a reliable contact and thus sealing can be achieved. The hollow chamber  46  which is under axial pressure acts like a pneumatic spring which guarantees permanently maintaining the sealing effect.