Abstract:
The assembly system has several profiled bars connected to each other, each of which has at least one clamping channel open to the outside with a bottom surface and two lateral surfaces. They are connected by an elongated or angled connecting element with two opposing external clamping surfaces, at least certain sections of which are straight, and an expansion joint extending between the external clamping surfaces. The connecting element is introduced into the clamping channel, and at least one spreading element is introduced into at least one section of the expansion joint in such a way that the external clamping surfaces of the connecting element are clamped against the lateral surfaces of the clamping channel of at least one profiled bar. The connecting element is covered at the ends by an extensible terminal element, which covers the expansion joint.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority based on European patent application EP 07 015 723.5, filed Aug. 9, 2007. 
       FIELD OF THE INVENTION 
       [0002]    The invention pertains to assembly systems which include several profiled bars connected to each other, and more particularly to assembly systems with a lightweight frame which securely hold flat bodies with precision, durability and safety. 
       BACKGROUND 
       [0003]    According to the prior art, assembly systems for lightweight frames are known and used to hold, for example, electrical or electronic devices. EP 1 420 140 A1 discloses a frame for holding a flat body, wherein the profiled bars are held together by a clamping element, which extends around the periphery and clamps the profiled bars together from inside the frame. These types of assembly systems suffer from the disadvantage that the retaining force with which the electrical or electronic device is held is limited at the connecting points. For outdoor use and for heavy loads, these types of assembly systems are unsuitable due to the intrinsic weight of the device to be supported. 
       SUMMARY OF THE INVENTION 
       [0004]    It is an object of the present invention to provide an assembly system which is universally suitable for holding flat bodies, offers the highest possible strength at the connecting points of the profiled bars, has a long service life, withstands any outdoor exposure, and can be manufactured and assembled quickly and at low cost. 
         [0005]    According to a first aspect of the invention, the assembly system includes several profiled bars connected to each other, each of which comprises at least one clamping channel open to the outside and has a bottom surface and two lateral surfaces. 
         [0006]    The assembly system includes a connecting element comprising two opposing external clamping surfaces, at least certain sections of which are straight, and an expansion joint extending between the external clamping surfaces. The connecting element is introduced into the clamping channel and includes at least one spreading element which is introduced into at least one section of the expansion joint in such a way that the external clamping surfaces of the connecting element are secured to or clamped against the lateral surfaces of the clamping channel of at least one profiled bar. 
         [0007]    The connecting element includes end surfaces each of which have an extensible terminal element covering the expansion joint. The extensible terminal element functions as a flexible spring to absorb expansion of the expansion joint when the spreading elements are introduced or driven into the expansion joint. 
         [0008]    The length of the expansion joint sections depends on the amount of clamping force required when the elements are pressed against each other. 
         [0009]    It is advantageous to increase the width of certain sections of the expansion joint so that openings are provided for the introduction of the spreading elements. The wider sections can be asymmetric with respect to the axis of the expansion joint, as a result of which the clamping force acquires a horizontal component in addition to a vertical component. 
         [0010]    It is also advantageous for at least parts of the lateral surfaces of the clamping channel to include a first ribbing and for at least parts of the external clamping surfaces of the connecting element to include a second ribbing, which extends transversely to the first ribbing, so that, as a result of the clamping operation, a type of permanent cold-weld joint is produced between the lateral surfaces of the clamping channel and the external clamping surfaces of the connecting element. In terms of the technical means required, ribbing of this type is easy to produce. The dimensions of the first and second ribbings are such that, when the ribbings are clamped against each other at essentially a right angle, a very strong non-positive connection is achieved. Depending on the material, the longitudinal and transverse ribs of the first and second ribbings will give way slightly as a result of deformation when they are pressed together. 
         [0011]    The spreading element may include a body-bound rivet, a grooved drive stud, a screw, or the like. These types of connecting components are available at very low cost and in a wide variety of sizes and materials. 
         [0012]    It is advantageous for the spreading element to be made of high-grade steel. It is preferable for the profiled bars and the connecting elements to be made of the same material, preferably aluminum. As a result, when the longitudinal and transverse ribs of the corresponding ribbings are pressed together, an especially strong joint is obtained by the production of a strong non-positive connection. Furthermore, aluminum profiles can be produced quickly and at low cost. In particular, the production of the connecting elements can be adapted flexibly to the depth of the clamping channel. Alternatively, as an example, the profiled bars and the connecting element can be made out of plastic. 
         [0013]    It is especially advantageous for the profiled bars to have 45° bevels at the ends to be connected and to be arranged next to each other at an angle. It is also advantageous for the connecting element to be designed as an angle-shaped connecting element. Thus the profiled bars can be connected to each other at an angle of essentially 90°, as is typical in frame construction. A conventional four-cornered frame construction with four profiled bars can thus be achieved with four angle-shaped connecting elements. Alternatively, profiled bars can be connected to each other at angles other than 90°. For this purpose the profiled bars will be beveled at an angle essentially equal to half of the angle formed by profiled bars when secured with the connecting element. 
         [0014]    It is also advantageous, furthermore, for two profiled bars with straight ends to be connected perpendicularly to each other and for at least one profiled bar to have two opposing projecting strips which project into the clamping channel. These strips are then able to engage in a groove located in the area of the external clamping surfaces. As a result, it is possible not only to connect the end surfaces of profiled bars to each other but also to connect the end surface of one profiled bar to the open side of the clamping channel of the other profiled bar. A connection of this type can be made permanent by providing a strong non-positive connection, or it can be made so that the one bar can slide longitudinally along the clamping channel of the other bar. 
         [0015]    According to another aspect of the present invention a flat frame-and-panel element includes the above described assembly system and an essentially flat body, preferably a solar panel, supported within the profiled bars. The frame supporting the solar panels must comprise a very high carrying capacity and strength at the connecting points, have a long service life, and withstand extreme exposure when used in an outdoor installation. These boundary conditions are fulfilled by the inventive assembly system for these types of flat support elements. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    Additional details, features, and advantages of the present invention can be derived from the following detailed description and the drawings. 
           [0017]      FIG. 1  is a perspective view of a first embodiment of the inventive assembly system, showing a profiled bar and two connecting elements; 
           [0018]      FIG. 2  is a perspective view of the embodiment of  FIG. 1 , showing two profiled bars, each of which has two clamping channels, connected to each other by means of a connecting element installed in each clamping channel; 
           [0019]      FIG. 3  is a side view of a connecting element according to the first embodiment of the invention illustrated in  FIGS. 1 and 2 ; 
           [0020]      FIG. 4  is a side view of a detail of the connecting element of  FIG. 3 ; 
           [0021]      FIG. 5  is a perspective view of a second embodiment of the inventive assembly system, showing two profiled bars connected to each other at a right angle by means of an angled connecting element; 
           [0022]      FIG. 6  is a side view of the angle-shaped connecting element of  FIG. 5 ; 
           [0023]      FIG. 7  is a perspective view of the angle-shaped connecting element of  FIG. 5 ; 
           [0024]      FIG. 8  is a perspective view of a third embodiment of the inventive assembly system, showing two profiled bars connected to each other in a T-shaped arrangement; 
           [0025]      FIG. 9  is a side view of the third embodiment of the inventive assembly system illustrated in  FIG. 8 ; 
           [0026]      FIG. 10  is a side view of the connecting element used in the third embodiment illustrated in  FIGS. 8 and 9 ; and 
           [0027]      FIG. 11  is a perspective view of the connecting element of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]      FIG. 1  illustrates the assembly system of the present invention  1  showing, for simplicity, one profiled bar  2  with its two clamping channels  4  (one of which is not visible), into each of which a connecting element  6  has been introduced. The connecting elements  6  are introduced from the end surface of profiled bar  2  approximately half-way into clamping channels  4 . Connecting elements  6  have external clamping surfaces  8  (only one clamping surface  8  is visible on each of two connecting elements  6  shown in  FIG. 1 ). Each of two connecting elements  6  comprises an expansion joint  10 , which, in the embodiment shown here, is widened into an opening at two points in both connecting elements  6 . The spreading elements  12 , which are designed as body-bound rivets in  FIG. 1 , can be introduced into these openings. 
         [0029]      FIG. 2  shows two profiled bars  2  in the connected state with the ends of each profiled bar  2  butted up against each other. Connecting elements  6  (only one connecting element  6  can be seen in  FIG. 2 ) are introduced approximately half-way into each of two clamping channels  4 . As a result of the clamping action of spreading elements  12 , which are driven all the way in through the entire length of the opening, the connecting elements connect the two bars tightly to each other.  FIG. 2  shows the lateral surfaces  16  on the inside of clamping channel  4  which include a first ribbing (not shown) extending in the longitudinal direction. External clamping surfaces  8  of connecting element  6  have a second ribbing  20  (see  FIG. 4 ) extending in the transverse direction. The very high strength of the connection is provided by a type of permanent cold-weld joint, which arises under pressure, between the two ribbings on lateral surfaces  16  of clamping channel  4  and on external clamping surfaces  8  of connecting element  6 . 
         [0030]    In the embodiment shown in  FIG. 2 , both profiled bars  2  and connecting elements  6  are made of aluminum. When the first and second ribbings, which are essentially perpendicular to each other, are pressed together, a very strong non-positive connection is formed. Another advantage of making connecting element  6  and profiled bar  2  out of the same material is that corrosion is avoided when the components are installed outdoors. 
         [0031]      FIG. 3  shows connecting element  6  including expansion joint  10  which is widened at two points on each side forming openings  14  into which spreading elements  12  (see  FIG. 1 ) can be inserted. In the embodiment shown in  FIG. 3 , openings  14  are asymmetric with respect to the longitudinal axis of the expansion joint. This offers the advantage that, when spreading elements  12  are introduced into openings  14 , external clamping surfaces  8  of connecting element  6  move not only in the vertical direction but also in opposite horizontal directions. As a result of such construction of connecting element  6 , an extremely strong connection is obtained between connecting element  6  and clamping channel  4  in the clamped state. At each of the longitudinal ends, connecting element  6  has an extensible terminal element  24 . As a result of extensible terminal element  24  spring-like extensibility, it can compensate for the different longitudinal movements of external clamping surfaces  8  during the clamping operation without causing the connection to lose strength. 
         [0032]    Connecting element  6  can be produced at low cost out of aluminum. The width of connecting element  6  can be varied in a flexible manner, depending on the depth of clamping channel  4  in profiled bar  2 . 
         [0033]      FIG. 4  shows connecting element  6  with second ribbing  20  of external clamping surface  8 . Second ribbing  20  is designed in such a way that the angle  22  between the rising and falling flanks of each rib of second ribbing  20  is about 90°. Other angles are possible, depending on the material being used and on the desired strength. 
         [0034]      FIG. 5  shows two profiled bars  2  arranged at a 90° angle to each other and formed to hold a flat body. Two profiled bars  2  are permanently connected to each other by an angle-shaped connecting element  6 . Spreading elements  12  are introduced at three points into expansion joint  10  of connecting element  6  to produce the clamping effect, one in each arm or sidepiece and one in the corner area of connecting element  6 . In the second embodiment shown in  FIG. 5 , profiled bars  2  are beveled 45° at their ends, which is half of the angle between the two bars. As a result of this beveling, clamping channel  4  acquires a slanted open end, into which the angle-shaped connecting element  6  is introduced when assembly system  1  is being constructed. As soon as profiled bars  2  are arranged accurately with respect to each other, spreading elements  12  can be introduced into the openings in expansion joint  10  in a first step of the assembly process. Depending on the length of the arms of the angle-shaped connecting element  6 , it is also possible to provide several widened areas for the introduction of spreading elements  12  into expansion joint  10 . The widened area in the corner of expansion joint  10  is optional. 
         [0035]    As in the case of the first embodiment, clamping channels  4  have a first, longitudinal ribbing  18  on their lateral surfaces  16 , and connecting element  6  has a second ribbing  20  on its external clamping surfaces  8  (see  FIG. 4 ). 
         [0036]      FIG. 6  is a side view of the angle-shaped connecting element  6  shown in  FIG. 5 . Like the first embodiment, the widened areas of expansion joint  14  on the sidepieces are offset from each other asymmetrically with respect to the corresponding longitudinal axis of the expansion joint. This construction provides the additional horizontal component of the clamping force produced when spreading elements  12  are introduced into openings  14  in the sidepieces. The clamping effect between external clamping surfaces  8  and lateral surfaces  16  of clamping channel  4  is achieved by movements in opposite directions of either side of connecting element  6 . Extensible terminal elements  24  formed on the ends of the angle-shaped connecting element  6  are able to absorb these oppositely directed clamping movements by undergoing elastic deformation without causing any loss of strength. 
         [0037]      FIG. 7  is a perspective view of the angle-shaped connecting element  6  of the assembly of  FIG. 6  showing second ribbing  20  on external clamping surfaces  8 . See the discussion concerning  FIG. 4  above for details of second ribbing  20  on external clamping surfaces  8  of connecting element  6 . 
         [0038]    As illustrated in  FIG. 8 , the end surfaces of two profiled bars  2 A and  2 B are not butted up against each other. Instead, the end surface of one profiled bar  2 A is arranged at essentially a right angle to second profile bar  2 B to form a T-shaped arrangement illustrating a third embodiment of the invention. In such a T-shaped arrangement, the end surface of first profiled bar  2 A is oriented to fit into the opening in clamping channel  4  of second profiled bar  2 B. As shown in  FIG. 8 , first profiled bar  2 A has two clamping channels  4 , and the end surfaces of these two channels, located at one end of the first profiled bar  2 A, face one of clamping channels  4  of second profiled bar  2 B. Connecting the first and second profiled bars  2 A and  2 B together is accomplished by introducing one end of connecting element  6  into the open end surface of clamping channel  4  of first profiled bar  2 A and pushing the connecting element  6  most of the way into the channel, so that its other end projects out of the clamping channel of first profiled bar  2 A. The length of the projection of connecting element  6  is approximately equal to the depth of clamping channel  4  of second profiled bar  2 B. This projecting end of connecting element  6  is introduced into clamping channel  4  of second profiled bar  2 B in such a way that connecting element  6  and second profiled bar  2 B are essentially perpendicular to each other. 
         [0039]      FIG. 9  is a side view of the clamping configuration illustrated in  FIG. 8  and thus the connection between two profiled bars  2 A and  2 B. As noted above profiled bars  2 A and  2 B are arranged at 90° to each other through the use of connecting element  6 , which is installed lengthwise in clamping channel  4  of first profiled bar  2 A and inserted into clamping channel  4  of second profiled bar  2 B at essentially a right angle. Spreading elements  12  are located so that they can be easily accessed for the clamping operation. One of spreading elements  12  is located as close as possible to the end of clamping channel  4  of first profiled bar  2 A to maximize the clamping effect. The free end of connecting element  6  is introduced laterally into connecting channel  4  of second profiled bar  2 B. Guidance is provided by projecting strips  26  of clamping channel  4 , each of which engages in a groove  28  in each side of connecting element  6 . 
         [0040]    Connecting element  6  of the third embodiment of the inventive assembly system is explained with reference to  FIG. 10 . Connecting element  6  of the third embodiment includes widened areas of expansion joint  10  which create openings  14 . Openings  14  are symmetric with respect to the axis of expansion joint  10  resulting in producing a clamping force that has essentially only a vertical component. Extensible terminal element  24  at the top end of connecting element  6  is designed so that it does not project beyond the external clamping surfaces. This ensures that the projection of connecting element  6  into clamping channel  4  of second profiled bar  2 B produces maximum contact between external clamping surfaces  8  and lateral surfaces  16  of clamping channel  4  (see  FIGS. 1 ,  2 ,  5  and  8 ). 
         [0041]      FIG. 11  is a perspective view of the connecting element shown in  FIG. 10 . External clamping surfaces  8  between the top end of the connecting element and the groove  28  are not provided with transverse ribbing, which makes it possible for first profiled bar  2 A to slide along clamping channel  4  of the second profiled bar  2 B. Ribbing  20  of the external clamping surfaces is provided only on one side of groove  28  which is inserted into profiled bar  2 A. As a result, as explained above, an optimal connecting action is guaranteed between connecting element  6  and clamping channel  4  of first profiled bar  2 A. 
         [0042]    In all of the embodiments shown here, it is advantageous, when pressing the spreading elements into the openings provided for their insertion, to start in the middle of the connecting element. The reason for this is that the force required to expand the expansion joint is the weakest in the middle of the connecting element, that is, in the area which is the farthest away from the extensible terminal elements. 
         [0043]    With respect to the ribbings of the external clamping surfaces of the connecting element and of the lateral surfaces of the clamping channel, it should also be pointed out that these can also extend in directions other than the transverse and longitudinal directions. In particular, it is not necessary for the ribbings to be at a 90° angle to each other. By way of example only, a 60° ribbing of the lateral surfaces of the clamping channel and of the external clamping surfaces of the connecting element is also possible. Many other angles are possible as necessary for an given configuration. 
         [0044]    The inventive assembly system can be used to hold a wide variety of flat bodies, depending on the design of the profiled bars. One such result is a flat frame-and-panel element configuration. Thus the inventive assembly system can be used for a wide variety of flat bodies, especially for very heavy photovoltaic modules which are installed outdoors and exposed to extreme weather conditions. Other examples of flat bodies which can be held by the inventive assembly system include LCD panels, panels of special glass, and the like. 
         [0045]    While the invention is shown in several forms, it is not limited to those embodiments illustrated, but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.