Patent Publication Number: US-11661778-B2

Title: High speed overhead door

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a 371 of PCT/EP2018/080115 filed on Nov. 5, 2018, published on May 16, 2019 under publication number WO 2019/091896, which claims priority benefits from Swedish Patent Application No. 1730307-4 filed on Nov. 8, 2017, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     Technical Field 
     The invention relates to an overhead door for covering a door opening comprising a door blade with a plurality of panels, said door blade being movable between a vertical, closed position and a horizontal, opened or overhead position within a side frame comprising double-sided a vertical track and a horizontal track, connected by a connecting portion, respectively, and with a belt or a chain associated with one side each of the said side frame to lift the panels from said vertical position to said horizontal position. 
     In this context, the indication horizontal track is a general definition, used for a track leading the door blade in a horizontal, opened or overhead position. This horizontal track runs in an upper part of the overhead door and does not have to be horizontal necessarily, but can be transversely as well. Thus, the angle between the not necessarily vertically extending vertical track and the not necessarily horizontally extending horizontal track can deviate from a right angle. 
     Description of Related Art 
     Exemplarily an overhead door is known from WO 2005/100730 A1. According to this document an overhead door is provided with a movable door element, comprising a flexible steel door blade with a rounded rectangular or rounded trapezoidal profile and with opposed side regions, which ride in a track when travelling between an opened and a closed position. The track includes a vertical and a horizontal part, as well as a link portion, operatively connected there between. Carriages including rollers are connected to the door blade to facilitate smooth running of the door blade in the tracks. 
     Further, sectional overhead doors are known, presenting door blades, providing a plurality of panels, connected by rigid hinges, placed on both ends of the panels and partly in the middle of the panels. Usually a lifting device, for example a steel rope, a belt or a chain is fixed at the bottom of the door blade and pulls up the door blade, thus, leading the operating forces from the bottom of the door blade to the top. This leads to the following disadvantages:
         (1) rigid hinges are required to push the panels into the open, horizontal position; the forces which operate on the hinges require maintenance, like lubrication, and exchange of the same;   (2) if the bottom panel is damaged, for example caused by a crash (exemplarily a forklift truck drives into the door blade), the lifting devices can&#39;t work any longer;   (3) the rigid hinges are often twisted after a crash which makes the movement of the door blade impossible; repairing time and costs are quite high.       

     Another disadvantage of the known overhead doors is that usually at minimum one set of rollers is used to guide the door blade in the tracks. This rollers move all the way over a complete operation process, thus creating noises and wear. 
     Closing an overhead door fast requires a force to push or pull the door blade from the horizontal position into the vertical position. Known high speed overhead door systems for instance, use pull down systems to close a door blade. The hinges load inverse and the panels follow with inertia. This causes a discontinuous movement of panels during the acceleration. Alternatively, overhead doors were closed by gravity or press down devices, like spring starters, thus, reducing the operation speed of the closing procedure compared to the opening procedure. 
     Known high speed doors are usually rollup doors, exemplarily known from EP 2 304 154 A1. This rollup door provides a door leaf comprising a plurality of ridged lamellae and a flexible strip as a lifting device for selectively lifting and lowering the door leaf. Also, rollup doors are known with a curtain made of soft plastic, like PVC. By rolling up the door leaf the diameter of the resulting top roll increases strongly. Further, as energy saving becomes more important at industrial high speed doors, to optimize the thermal insulation and to increase the wind stability, the thickness of the door leaf increases more. Therefore a big spatial need over a lintel is required. Often this does not fit to applications with limited space over the lintel. To reduce the required spatial need over the lintel significant, overhead doors are used instead of rollup doors. 
     BRIEF SUMMARY 
     Having regard to the state of art, the invention&#39;s purpose is to develop the stated overhead door in a way that the advantages of a high speed rollup door and the advantages of an overhead door are combined, to offer an overhead door with a low space requirement above, low maintenance requirements and a high speed opening and closing possibility. 
     The technical problem outlined above is solved by an overhead door as stated above, comprising driving means for simultaneously driving a plurality of said panels. 
     In this way, during the closing procedure, a plurality of panels can be accelerated simultaneously by the driving means, thus, leading to a smooth start of the closing procedure and facilitating a high closing speed. 
     In a preferred embodiment of the invention the driving means comprise a conveyor belt system adjacent to the horizontal track. The horizontal track can run transverse or perpendicular to the vertical track. Said conveyor belt system is at least in said horizontal position of said door blade in engagement at least partially with the door blade. In particular, said conveyor belt system is at least in said horizontal position of said door blade in engagement at least partially with the said belt, being fixed to said door blade. 
     Said conveyor belt system can transport said door blade. Instead of a conveyor belt system said driving means can comprise a flexible toothed rack or a timing belt. 
     In a preferred embodiment of the invention said panels have a height from 100 mm to 350 mm, preferably from 150 mm to 300 mm, particularly preferably from 200 mm to 250 mm. The reduced height of the panels enables the overhead door to lift fast, especially around a curved shaped guideway. 
     As a further improvement of the solution said panels are guided sliding in said side frame. Thus, no rollers are required for vertical guiding. Therefore, the creating of noises and wear is reduced. 
     In another preferred embodiment, the overhead door is characterized by end pieces. Preferably two of said end pieces are assigned to one of said panels each. Thereby one of said end pieces is fitted in longitudinal direction to a first end of a panel. Another of said end pieces is fitted in longitudinal direction to a second end of a panel. Said end pieces fitted to the first end of said panels and said end pieces fitted to the second end of said panels are fixed to one belt, respectively. In particular said belt is constructed as flexible, flat belt. Said belt can be constructed as a flexible cord or as a flexible metal strip. In particular, said belt can be constructed as a rigid belt, cord or metal strip, being flexible enough to be guided around a curved shaped guideway. Said belt can work as a flexible hinge. The use of a belt as flexible hinge limits the damage after a crash, as compared to the use of ridged hinges to connect panels. Further, said belt can work as lifting device, to lift the door blade. As the end pieces of the panels are fixed to the belt each, even if the bottom panel is damaged, the opening and closing procedure can work properly. Also, by using a belt no maintenance would be required on hinges. Further, by using a belt, panels or the position of a panel can be changed fast and more easily, compared to the use of hinges to connect panels. 
     As a further improvement of the solution at an upper end of said belt additional end pieces can be fixed without being fitted to said panels. This enables said belt to be pulled in an accurate radius around a curved connection part, connecting said vertical track and said horizontal track by using said guideway. In a preferred embodiment of the invention two or three additional end pieces can be fixed without being fitted to said panels. 
     As a further improvement of the solution said conveyor belt system is powered by a drum axis. Said drum axis can have a rotation axis. Said drum axis can be turned around said rotation axis. Depending on the direction said drum axis is turned around said rotation axis, said conveyor belt system can be driven in one direction or in another direction. In particular, a transmission element can be used to couple said conveyor belt system with said drum axis. 
     In another preferred embodiment said drum axis extends in parallel to said panels. Preferably said drum axis is arranged in a transition region between said vertical tracks and said horizontal tracks. Preferably said drum axis is carried by a support means. The support means can be used to couple said drum axis to a motor, which can power said drum axis. When powering said drum axis, said drum axis can be turned around a rotation axis. In particular, said rotation axis of said drum axis can run lengthwise to the spreading direction of said drum axis. 
     In another preferred embodiment, the overhead door is characterized by at least one disc. Preferably said disc is assigned to said drum axis. In particular two discs are assigned in axial direction to a first end and/or to a second end of said drum axis, respectively. In other words, lengthwise to the spreading direction of said drum axis, two discs are arranged on a first side of the drum axis and two discs are arranged on a second side of the drum axis, respectively. Preferably two discs are arranged to a first end and/or a second end of a drum supported to the drum axis, respectively. In particular, said disc can rotate free on said drum. Further said conveyor belt system can be coupled to said disc by using a transmission element. 
     In another preferred embodiment, the overhead door is characterized by at least one gearwheel. Preferably said gearwheel is assigned to said drum axis. In particular two gearwheels are assigned in axial direction to a first end and/or to a second end of said drum axis, respectively. Further said conveyor belt system can be coupled to said disc by using a transmission element. Said gearwheel can be used as transmission drive between said drum axis and said conveyor belt system. In particular said gearwheel can be used to connect said drum axis with one cogwheel or one wheel of the conveyor belt system. 
     In another preferred embodiment, the overhead door is characterized by at least one blade spring or tension spring or weight. Preferably said spring or weight is assigned to said drum axis. In particular two or more springs are assigned in axial direction to a first end and to a second end of said drum axis, respectively. Said springs can be connected to a drum shaft, provided double-sided of said drum axis. Said drum shaft can be provided by said side frames. Said blade springs can be used to support a motor, which powers said drum axis. Further said blade springs can be used to balance said door blade. 
     As a further improvement of the solution said conveyor belt system comprises one, preferably two cogwheels, a conveyor belt, a chain and/or a plurality of wheels. Preferably said conveyor belt system comprises two cogwheels. A first cogwheel and a second cogwheel can be arranged on both sides of the conveyor belt system, respectively, averted from each other. Said first cogwheel can be arranged on that side of said conveyor belt system adjacent to said disc. Said second cogwheel can be arranged on that side of said conveyor belt system averted from said disc. Said conveyor belt can extend lengthwise along said conveyor belt system. In particular said conveyor belt can circulate said cogwheels or said plurality of wheels. Alternatively said conveyor belt can circulate said cogwheels and said plurality of wheels. By doing so, said cogwheels or said wheels guide and stabilize said conveyor belt. 
     In another preferred embodiment, the overhead door is characterized by a bracket. Said bracket couples said conveyor belt system with an upper end of said belt. In particular said bracket couples said conveyor belt of said conveyor belt system with an upper end of said belt. By doing so, when the conveyor belt system is actuated, said conveyor belt moves. In accordance with the movement of said conveyor belt said bracket moves and simultaneously said belt is moved. In this way, the door blade can be moved from a vertical to a horizontal, opened or overhead position, or the other way around, depending on the direction of movement of the conveyor belt. As a further improvement of the solution said door blade is guided above said conveyor belt of said conveyor belt system. 
     In another preferred embodiment, the overhead door is characterized by a transmission element. Said transmission element couples said conveyor belt system with said drum axis or said gearwheel. In particular said transmission element couples said cogwheel or any of said other wheels of said conveyor belt system with said drum axis or said gearwheel. Especially said transmission element couples said cogwheel and any of said other wheels of said conveyor belt system with said drum axis or said gearwheel. By coupling said conveyor belt system with said drum axis or said gearwheel by using said transmission element, said drum axis can power the conveyor belt system by turning around its rotation axis. Said transmission element can be constructed as a transfer belt. Said gearwheel can be coupled to said drum axis. 
     In another preferred embodiment, the overhead door is characterized by a motor. Preferably said motor is coupled to a gear box. Said motor is coupled to said drum axis. Alternatively said motor is coupled to said cogwheels or any of said other wheels of the conveyor belt system. The motor can be used to power the drum axis. Also, the motor can be used to power the conveyor belt system. 
     As a further improvement of the solution said connection portion comprises a guideway with a disc, at least one wheel, a support belt and/or a curve guiding. Said connecting portion connects said vertical track and said horizontal track. 
     The above described driving attachment allows transferring the operating forces to all of said panels, in particular from said panels in a horizontal position to said panels in a vertical position. Further, this kind of driving attachment is largely maintenance-free. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Hereinafter preferred embodiments of the invention will be described with reference to the attached figures. The figures show: 
         FIG.  1    a schematic rear view of a first embodiment of an overhead door with the features of the invention in a closed state, 
         FIG.  2    a schematic sectional top view of the overhead door in accordance with  FIG.  1   , presenting the overhead door in a closed state, 
         FIG.  3    a schematic sectional view of the overhead door in accordance with  FIG.  1   , presenting the overhead door in a closed state, 
         FIG.  4    a schematic sectional view of the overhead door in accordance with  FIG.  1   , presenting the overhead door in an opened state, 
         FIG.  5    a schematic sectional view of a second embodiment of the overhead door with the features of the invention in an opened state, 
         FIG.  6    a schematic section of a third embodiment of an overhead door with the features of the invention in a closed state, 
         FIG.  7    a schematic section of a fourth embodiment of an overhead door with the features of the invention in a closed state, 
         FIG.  8    a schematic section of a fifth embodiment of an overhead door with the features of the invention in a closed state, and 
         FIG.  9    a schematic section of another embodiment of an overhead door with the features of the invention in a closed state. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a schematic rear view of a first embodiment of an overhead door  10  with the features of the invention in a closed state. The overhead door  10  has a door blade  11  for covering a door opening  45 , running in a side frame  12 . In the shown example, the door blade  11  covers a door opening surrounded double-sided by a wall  42  and by a ceiling  43  above. The side frame  12  has double-sided a vertical track  13 , provided as a guiding element on the left and on the right side of the door blade  11 , respectively. Further, the side frame  12  has double-sided a horizontal track  14 . The horizontal track  14  runs transversely to the vertical track  13 , extending rearward to the door blade  11  in front view. In this example the horizontal track  14  runs perpendicular to the vertical track  13 . A connecting portion  15  with a curved shape connects the vertical track  13  and the horizontal track  14 , providing a guideway  16 . The horizontal tracks  14  of the side frame  12  are fixed at a rear side  46  (see  FIG.  4   ) below the ceiling  43 . At a front side the horizontal tracks  14  are fixed at the vertical tracks  13  of the side frames  12 , respectively. 
     The door blade  11  comprises a plurality of panels  17 . The shown door blade  11  comprises ten panels  17 , consisting of a rigid material. To provide a better overview, reference signs are only attached to two panels  17 . Each of the panels  17  has a height of two hundred millimeters. Further, each of the panels  17  provides two end pieces  18 , one end peace  18  of a panel  17  is shown in  FIGS.  2  to  9   . To provide a better overview, reference signs are only attached to few end pieces  18  in  FIGS.  2  to  9   . The end pieces  18  are arranged lengthwise on both sides of each panel  17 , respectively. The end pieces  18  of the panels  17  run in vertical direction in slots  19 , provided double-sided on the vertical track  13  of the side frame  12 . 
     The panels  17  are connected to a belt  20 . For doing so, one belt  20  connects the end pieces  18  of the panels  17  on both sides of the panels  17 , respectively. Thereby the belt  20  works as a lifting device and as a hinge between the panels  17 . The belt  20  runs in vertical direction in the slot  19  on both sides of the vertical track  13  of the side frame  12 , respectively. In the shown example the belts  20  are constructed as flexible, flat belts  20 . 
     Adjacent to the connecting portion  15 , a drum  21  is arranged. The drum  21  extends horizontally between both sides of the side frame  12 . The drum  21  is mounted rotatable on a drum axis  51 . The drum axis  51  is mounted rotatable on support means  49 , not shown in this figure. Double-sided to the drum  21  two discs  22  are arranged. In the pictured execution example, the discs  22  represent at the same time the guideway  16  of the connecting portion  15  between the vertical track  13  and the horizontal track  14 . By using two discs  22  as guideway, the load of the connection between the panels  17  and the corresponding end pieces  18  can be reduced. Alternatively, instead of two discs  22  a single broad disc could be used as guideway. A transmission element  23  is provided, coupling the drum axis  51  and the horizontal track  14  on both sides of the side frame  12 , respectively, shown detail in  FIGS.  3  and  4   . 
     Further, adjacent to the drum axis  51  a gear box  24  and a motor  25  are arranged. Further, support means  49  are arranged adjacent to the drum axis  51  for supporting the same. In the shown example, the gear box  24  and the motor  25  are arranged on the right side of the drum axis  51 . The gear box  24  is connected to the motor  25 . The motor  25  is coupled via the gear box  24  to the drum axis  51 . The gear box  24  and the motor  25  are used to power the drum axis  51 . Double-sided of the drum axis  51  springs  26  are arranged. In the shown example the springs  26  are designed as blade springs  26 . Two blade springs  26  are arranged on each side of the drum axis  51 , respectively. In other words, lengthwise to the axial direction of said drum axis  51 , two blade springs  26  are arranged on a first side of the drum axis  51  and two blade springs  26  are arranged on a second side of the drum axis  51 . The blade springs  26  extend in vertical direction, parallel to the vertical track  13  in the side frame  12 , respectively. The blade springs  26  support the motor  25 . 
       FIG.  2    shows a schematic sectional top view of the overhead door  10  in accordance with  FIG.  1   , presenting the overhead door  10  in a closed state. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway, in this example represented by the two discs  22 . 
     In this top view, only a single panel  17  and a single end piece  18  are visible. The end pieces  18  of the panels  17  run in vertical direction in the slot  19 . The panels  17  are connected to the belt  20 . 
     The drum axis  51  is mounted rotatable on support means  49 . Adjacent to the drum axis  51  a gear box  24 , a motor  25 , which is not shown in this figure, and two blade springs  26  are arranged. 
     The horizontal track  14  has a conveyor belt system  27 . The conveyor belt system  27  extends lengthwise along the horizontal track  14 . A second conveyor belt system  27  is provided on the right side of the side frame  12 , not visible in this view. The conveyor belt system  27  has a conveyor belt  40 . In the pictured execution example the conveyor belt  40  is constructed as a timing belt. Alternatively the conveyor belt  40  can be constructed as a chain. Further, the conveyor belt system  27  has a first cogwheel  28 . The first cogwheel  28  and the drum axis  51  are coupled by the transmission element  23  on both sides of the side frame  12 , respectively. Coupling the first cogwheel  28  and the drum axis  51 , the transmission element  23  circulates the cogwheel  28  and a wheel disc  50  of the drum axis  51 . 
       FIG.  3    shows a schematic sectional view of the overhead door  10  in accordance with  FIG.  1   , presenting the overhead door  10  in a closed state. In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway, in this example represented by the discs  22 , of which only one disc  22  is visible in this figure. 
     A bottom sealing  47  is provided on that panel  17  being located adjacent to the ground. To provide a better overview, the panels  17  are shown without end pieces  18 . At the upper end of the belt  20  additional end pieces  18  are fixed without being fitted to panels  17 . In the shown example, three additional end pieces  18  are fixed at the upper end of the belt  20 , without being fitted to panels  17 . This enables the belt  20  to be pulled in an accurate radius around the curved connection portion  15  as the discs  22  are used as guideway. 
     The conveyor belt system  27  extends lengthwise along the horizontal track  14 . The conveyor belt system  27  has a conveyor belt  40 , a first cogwheel  28  and a second cogwheel  29 . The first cogwheel  28  and the second cogwheel  29  are arranged on both sides of the conveyor belt system  27 , respectively, averted from each other. The first cogwheel  28  is arranged on that side of the conveyor belt system  27  adjacent to the drum axis  51 . The second cogwheel  29  is arranged on that side of the conveyor belt system  27  averted from the drum axis  51 . The conveyor belt  40  extends lengthwise along the conveyor belt system  27 , circulating the cogwheels  28 ,  29 . 
     The first cogwheel  28  and the drum axis  51  are coupled by the transmission element  23  on both sides of the side frame  12 , respectively. 
     On an upper end of the belt  20  a bracket  30  is provided. The bracket  30  is connected with the conveyor belt  40  of the conveyor belt system  27 . By doing so, the belt  20  is coupled with the conveyor belt system  27 . In the closed state of the overhead door  10 , the bracket  30  is located on the conveyor belt  40  of the conveyor belt system  27  adjacent to the first cogwheel  28 . 
       FIG.  4    shows a schematic sectional view of the overhead door  10  in accordance with  FIG.  1   , presenting the overhead door  10  in an opened state. In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely opened. The door blade  11  is moved to the horizontal track  14  of the side frame  12 . To provide a better overview, only seven of the ten panels  17  are shown. The vertical track  13  and the horizontal track  14  are connected by a guideway, represented by the discs  22 , of which only one disc  22  is visible in this figure. At the upper end of the belt  20  three additional end pieces  18  are fixed without being fitted to panels  17 . Depending on the radius of the disc  22  and the height of the panels  17 , more or less than three additional end pieces  18 , not being fitted to panels  17 , are possible. 
     The first cogwheel  28  and the drum axis  51  are coupled by the transmission element  23  on both sides of the side frame  12 , respectively. 
     The bracket  30  is provided on the upper end of the belt  20 , connected to the conveyor belt  40  of the conveyor belt system  27 . In the opened state of the overhead door  10 , the bracket  30  is located on the conveyor belt  40  of the conveyor belt system  27  adjacent to the second cogwheel  29 . 
       FIG.  5    shows a schematic section of a second embodiment of an overhead door  48  with the features of the invention, in an opened state. The operating principle of the overhead door  48  is comparable to those of the overhead door  10 , therefore, similar objects are signed with the identical reference signs. 
     In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely opened. The overhead door  48  only differs from the overhead door  10  in its orientation of the horizontal track  14  of the side frame  12  to the vertical track  13  of the side frame  12 . In this embodiment, the horizontal track  14 , extending rearward to the door blade  11 , does not run perpendicular to the vertical track  13 . The angle between the horizontal track  14  and the vertical track  13  is more than 90°. Thus, a back area of the horizontal track  14  is lifted up compared to a front area of the horizontal track  14 , which is faced to the vertical track  13 . 
       FIG.  6    shows a schematic section of a third embodiment of an overhead door  31  with the features of the invention, in a closed state. The operating principle of the overhead door  31  is comparable to those of the overhead door  10 , therefore, similar objects are signed with the identical reference signs. 
     In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway. In the shown example the guideway is represented by a plurality of wheels  32 . In this example, the guideway comprises eight wheels  32 . To provide a better overview, reference signs are only attached to two wheels  32 . The wheels  32  are arranged in line in the connecting portion  15 , following the curved shape of the connecting portion  15 . The first cogwheel  28  is coupled with a gearwheel  41  by using the transmission element  23  on both sides of the side frame  12 , respectively. The gearwheel  41  is driven by the motor  25 . 
     To provide a better overview, the panels  17  are shown without end pieces  18 . At the upper end of the belt  20  three additional end pieces  18  are fixed without being fitted to panels  17 . 
       FIG.  7    shows a schematic section of a fourth embodiment of an overhead door  33  with the features of the invention, in a closed state. The operating principle of the overhead door  33  is comparable to those of the previously described overhead doors  10 ,  31 , therefore, similar objects are signed with the identical reference signs. 
     In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway. In the shown example the guideway is represented by a support belt  34  supported by a plurality of wheels  35 . In this example, the guideway comprises six wheels  35 . To provide a better overview, reference signs are only attached to two wheels  35 . The wheels  35  are arranged in line in the connecting portion  15 , following the curved shape of the connecting portion  15 . The support belt  34  circulates the wheels  35 . The first cogwheel  28  is coupled with the gearwheel  41  by using the transmission element  23  on both sides of the side frame  12 , respectively. The gearwheel  41  is driven by the motor  25 . 
     To provide a better overview, the panels  17  are shown without end pieces  18 . At the upper end of the belt  20  three additional end pieces  18  are fixed without being fitted to panels  17 . 
       FIG.  8    shows a schematic section of a fifth embodiment of an overhead door  36  with the features of the invention, in a closed state. The operating principle of the overhead door  36  is comparable to those of the previously described overhead doors  10 ,  31 ,  33 , therefore, similar objects are signed with the identical reference signs. 
     In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway. In the shown example the conveyor belt system  27 , in particular the conveyor belt  40 , represents at the same time a guideway. By doing so, the conveyor belt system  27  has a plurality of wheels  35 . The wheels  35  are arranged in line in the connecting portion  15 , following the curved shape of the connecting portion  15 . Further, the conveyor belt system  27  has a wheel  37 . In the shown example, the wheel  37  differentiates from the wheel  35  in its size. In this execution example the wheel  37  is of bigger size compared to the wheels  35 . Further, the wheel  37  is adjustable to tension the conveyor belt  40 . The wheel  37  is located between the line of wheels  35  and the gearwheel  41 . Further, the conveyor belt system  27  has a second cogwheel  29 , not shown in this figure, arranged on that side of conveyor belt system  27  averted to the disc  22 . In the shown example the conveyor belt system  27  do not have a first cogwheel  28 . The conveyor belt  40  of the conveyor belt system  27  circulates the wheels  35 ,  37  and the cogwheel  29 . The gearwheel  41  is coupled with one of the wheels  35  by the transmission element  23  on both sides of the side frame  12 , respectively. The gearwheel  41  is driven by the motor  25 . 
     To provide a better overview, the panels  17  are shown without end pieces  18 . At the upper end of the belt  20  three additional end pieces  18  are fixed without being fitted to panels  17 . 
       FIG.  9    shows a schematic section of another embodiment of an overhead door  38  with the features of the invention, in a closed state. The operating principle of the overhead door  38  is comparable to those of the previously described overhead doors  10 ,  31 ,  33 ,  36 , therefore, similar objects are signed with the identical reference signs. 
     In this view, only the left side of the side frame  12  is visible. The door opening  45  is completely closed by the door blade  11 . Thereby the door blade  11  is located between the vertical tracks  13  of the side frame  12 . The vertical track  13  and the horizontal track  14  are connected by a guideway. In the shown example the guideway is represented by a curve guiding  39 . The curve guiding  39  has a curved shaped adjusted to the shape of the connecting portion  15 . In the shown example the curve guiding  39  consists of a rigid material. To reduce friction, in this example the sliding surface is covered with a low friction material  44 . The first cogwheel  28  is coupled with the gearwheel  41  by using the transmission element  23  on both sides of the side frame  12 , respectively. The gearwheel  41  is driven by the motor  25 . 
     To provide a better overview, the panels  17  are shown without end pieces  18 . At the upper end of the belt  20  three additional end pieces  18  are fixed without being fitted to panels  17 . 
     The operating principle of the overhead door  10 ,  31 ,  33 ,  36 ,  38 ,  48  according to the invention will be explained hereinafter according to the  FIGS.  1  to  9   : 
     To open the overhead door  10 ,  31 ,  33 ,  36 ,  38 ,  48  the door blade  11  has to be pulled up from the vertical position to the horizontal position. 
     The gear box  24  and the motor  25  are used to turn the drum axis  51  and simultaneously the conveyor belt  40 , which are arranged on both sides of the drum axis  51 , respectively. The drum axis  51  and the conveyor belt  40  are coupled by the transmission element  23  and the cogwheel  28  and/or any other wheel  35 ,  37  of the conveyor belt systems  27  on both sides of the side frame  12 , respectively. By turning the drum axis  51 , the conveyor belt systems  27  are actuated. Thereby, the conveyor belt  40  of the conveyor belt systems  27  moves in the direction averted from the door blade  11 . The conveyor belt  40  of the conveyor belt system  27  is coupled with the belt  20  by using a bracket  30 . Thus, when the conveyor belt system  27  is actuated, both belts  20  were pulled synchronous with same speed upwards to the horizontal track  14 , thereby pulling the door blade  11  upwards. Doing so, the panels  17  are guided upwards sliding in the side frame  12 . 
     To guide the door blade  11  from the vertical track  13  to the horizontal track  14 , the end pieces  18  of the panels  17  can be move around the curved connecting portion  15  by using different guideways  16 :
     (1) the end pieces  18  can be transported by rotatable discs  22  as shown in  FIGS.  1  to  5   ,   (2) the end pieces  18  can be rolled over a line of wheels  32  as shown in  FIG.  6   ,   (3) the end pieces  18  can be move over a support belt  34  supported by wheels  35  as shown in  FIG.  7   ,   (4) the end pieces  18  can be transported by the conveyor belt  40  of the conveyor belt system  27 ; in this case the conveyor belt  40  runs over the wheels  35 ,  37  as shown in  FIG.  8   , or   (5) the end pieces  18  can slide over a rigid curve guiding  39  as shown in  FIG.  9   .   

     By turning the drum axis  51  in the opposite direction, the conveyor belt systems  27  transport the panels  17  the other way around from the horizontal track  14  around the curved connection portion  15  into the vertical track  13 . As nearly all panels  17  are actively transported, there is no relative movement between the panels  17  and the conveyor belt  40  of the conveyor belt system  27 . 
     REFERENCE NUMERALS 
     
         
           10  overhead door 
           11  door blade 
           12  side frame 
           13  vertical track 
           14  horizontal track 
           15  connecting portion 
           16  guideway 
           17  panel 
           18  end piece 
           19  slot 
           20  belt 
           21  drum 
           22  disc 
           23  transmission element 
           24  gear box 
           25  motor 
           26  blade spring 
           27  conveyor belt system 
           28  first cogwheel 
           29  second cogwheel 
           30  bracket 
           31  overhead door 
           32  wheel 
           33  overhead door 
           34  support belt 
           35  wheel 
           36  overhead door 
           37  wheel 
           38  overhead door 
           39  curve guiding 
           40  conveyor belt 
           41  gearwheel 
           42  wall 
           43  ceiling 
           44  low friction material 
           45  door opening 
           46  rear side 
           47  bottom sealing 
           48  overhead door 
           49  support means 
           50  wheel disc 
           51  drum axis