A multi-section roll-up curtain is raised and lowered by plural support/rotational drive mechanisms disposed in a spaced manner along the length of the curtain. Each drive mechanism is symmetrically loaded with a curtain section attached to opposed sides of each drive mechanism. Each curtain section includes plural vertically spaced curtains which are simultaneously rolled-up and unrolled. Each drive mechanism includes plural vertically spaced drive motors each connected to first and second curtain-bearing roll-up tubes disposed on opposite sides of a drive motor. A generally vertical guide member is coupled to each drive motor by a respective carriage assembly allowing the drive motors to travel up in rolling up the curtains and down in unrolling the curtains. This arrangement accommodates the large torques encountered in operating long curtain sections permitting multi-section curtains 600′ and longer in length to be reliably and safely operated without using large, powerful motors.

FIELD OF THE INVENTION 
     This invention relates generally to multi-section roll-up curtains, where each section includes plural vertically aligned curtains which are simultaneously rolled-up and unrolled, and is particularly directed to very long, multi-section curtains and a curtain support/rotational drive arrangement capable of accommodating the large torques encountered in these types of curtains. 
     BACKGROUND OF THE INVENTION 
     A common type of flexible door employs a drive mechanism for raising and lowering the door and includes an electrically powered motor which applies torque to a roller causing the door to wind up on or to unwind from the roller in positioning the door in either the open or closed position, or any position therebetween. A common type of flexible curtain is comprised of a lightweight, strong fabric material and includes an electric motor typically connected to a roller mechanism via a reduction gear to reduce the number of revolutions of the electric motor per unit distance of travel of the flexible door in raising and lowering the door. Movable structures of this type can be used either to cover an opening, such as a doorway in a building structure, or they may be used as a movable partition, wall or curtain in the structure. 
     When used as a partition, or curtain, this roll-up structure may span large distances in the building structure. These types of flexible curtains isolate the inside of the building structure from the elements, such as wind, rain, snow and sunlight, while permitting the building structure to be opened up so as to provide access to the outside when the environment is more hospitable. 
     As the applications for these types of flexible curtains have increased, additional demands have been placed on their structure and operation. For example, these types of flexible curtains are being used to span increasingly longer distances within the building structure. This, of course, places increasing demands upon the curtain support and drive, or displacement, system. Higher power ratings are required for the curtain drive mechanism, which typically includes an electrically powered motor, for increasing heights and horizontal distances spanned by the curtain. In addition, the curtain support system, which typically includes a horizontal, elongated rod, must be stronger to accommodate the increased weight of curtains spanning larger openings and must itself be lightweight to compensate for the increased weight of the curtain. This further increases the power requirements to operate the flexible curtain. In addition, the increased weight of the curtain with longer curtain lengths gives rise to the application of large torques arising from the unwinding forces exerted by the long length of the rolled-up curtain on the curtain support/drive mechanism. This increased torque places increased stress on the curtain support structure and drive mechanism. Where a roll-up rod is attached to a lower end of the flexible curtain, a complicated displacement and support mechanism is typically required to accommodate vertical movement of the rod during curtain roll-up and unrolling. 
     These types of curtains are increasingly being used in dairy barns wherein large numbers of cows are maintained and housed. Roll-up curtains are particularly adapted for this type of environment because they allow for easy and quick control of air flow as well as access to the outside environment. Sufficient ventilation is important in this environment to allow warm moisture to escape, to protect the cows from drafts and cold winter air, and to keep the cows dry. The increase in the size of herds has increased the demand for larger buildings offering improved ventilation and environmental isolation characteristics. This has necessitated the adoption of curtains of longer length with corresponding increased demands on the curtain support structure and drive mechanism. 
     The present invention addresses the aforementioned increased demands on roll-up curtains used in various applications by providing a curtain support and drive arrangement which accommodates the increased weights of longer curtain sections forming the walls of larger structures. The curtain support and drive arrangements used in the present invention are particularly designed to accommodate the large torques encountered when operating roll-up curtains of increased length. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a multi-section roll-up curtain incorporating plural drive mechanisms arranged in a spaced manner along the length of the curtain to accommodate curtains spanning very long distances, i.e., as long as 600′ in length. 
     Another object of the present invention to incorporate a counter force in the rotary drive mechanism of a roll-up curtain to accommodate the large torque exerted by very long length and/or very large height curtains on the curtain support/rotary drive mechanism. 
     Still another object of the present invention is to reduce the mechanical stress on and prolong the operating lifetime of a rotary drive mechanism used in raising and lowering a roll-up curtain by applying the force of the curtain's weight symmetrically to the curtain support/rotary drive mechanism. 
     It is another object of the present invention is to provide a drive arrangement for a roll-up curtain which is easily installed, highly reliable, comprised of a small number of easily assembled components, and capable of accommodating the weight of large curtains. 
     This invention contemplates a roll-up curtain comprising: a first curtain section including a first fixed upper rod attached to a support structure and a second lower rod; a second curtain section including a third fixed upper rod attached to the support structure and a fourth lower rod, wherein the second curtain section is aligned with and laterally spaced from the first curtain section; a rotary drive disposed intermediate the first and second curtain sections and coupled to the second and fourth lower rods for rotationally displacing the second and fourth lower rods in a first direction for rolling up the first curtain section on the second lower rod and the second curtain section on the fourth lower rod in opening the first and second curtain sections, and for rotationally displacing the second and fourth lower rods in a second opposed direction for unrolling the first curtain section from the second lower rod and the second curtain section from the fourth lower rod in closing the first and second curtain sections; and a vertical guide engaging the rotary drive for directing the rotary drive in vertical travel upward during rolling up of the curtain sections and downward during unrolling of the curtain sections and maintaining the rotary drive a fixed distance from and in a fixed orientation relative to the first and second curtain sections during rolling up and unrolling of the curtain sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The appended claims set forth those novel features which characterize the invention. However, the invention itself, as well as further objects and advantages thereof, will best be understood by reference to the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which: 
         FIG. 1  is a perspective view of a multi-section roll-up curtain assembly in accordance with the principles of the present invention; 
         FIG. 2  is a perspective view of a curtain support/drive mechanism for raising and lowering plural curtain sections in the roll-up curtain assembly of the present invention; 
         FIG. 3  is an upper perspective view of a curtain rotary drive and displacement assembly used in the roll-up curtain of the present invention; 
         FIG. 4  is a partial perspective view showing a sensor arrangement for limiting the upward and downward movement of a curtain section in accordance with one aspect of the present invention; 
         FIG. 5  is a simplified combined block and schematic diagram of a control system for use in controlling the roll-up curtain assembly of the present invention; 
         FIG. 6  is a lower perspective view of the curtain drive and displacement assembly shown in  FIG. 3 ; and 
         FIG. 7  is a bottom view of the curtain drive assembly shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , there is shown a perspective view of multi-section roll-up curtain assembly  10  in accordance with the present invention. Roll-up curtain assembly  10  includes first, second and third curtain sections  12 ,  14  and  16  disposed in a laterally spaced array over an opening in a building structure. Each of the first, second and third curtain sections  12 ,  14  and  16  includes an upper curtain and a lower curtain capable of being moved between a rolled-up position, wherein the curtain is opened, and an unrolled position, wherein the curtain sections fully cover the opening in the building structure. Thus, the first curtain section  12  includes an upper curtain  18  and a lower curtain  20 . The second curtain section  14  includes upper curtain  22  and lower curtain  24 . Finally, the third curtain section  16  includes upper curtain  26  and lower curtain  28 . The lower curtain  20  of the first curtain section  12  includes an upper portion  20   a  and lower portion  20   b . Similarly, the lower curtain  24  of the second curtain section  14  includes upper portion  24   a  and lower portion  24   b . Finally, lower curtain  28  includes an upper portion  28   a  and a lower portion  28   b.    
     The opening in the building structure over which the roll-up curtain assembly  10  is positioned is defined by an upper support member  40 , a lower support member  42 , and a pair of lateral limits to the opening which are not shown in  FIG. 1  for simplicity. The upper and lower support members  40 ,  42  are connected to and integral with the building structure, which also is not shown in the figure for simplicity. 
     Disposed within each of the aforementioned curtain sections are plural hems which extend the length of the curtain section and which are each adapted to receive a respective elongated, linear, tubular rod extending the length of the curtain section. Thus, upper curtain section  22  includes upper and lower hems respectively adapted to receive an upper support rod  55  and a lower drive rod  60 . Similarly, upper curtain section  26  includes upper and lower hems which are adapted to receive an upper support rod  57  and a lower drive rod  62 , respectively. Finally, upper curtain section  18  includes upper and lower hems which are adapted to receive an upper support rod  56  and a lower drive rod  61 , respectively. Each of the aforementioned upper support rods is securely attached to the upper support member  40 , or another structural member within the building structure, by means of a conventional connecting bracket which is not shown in the figure for simplicity. 
     Similarly, lower curtain  24  is provided with plural spaced hems which are adapted to receive an upper support rod  58   a , an intermediate drive rod  64  and a lower rod  63   a . Lower curtain  28  is adapted to receive an upper support rod  58   b , an intermediate or drive rod  66  and a lower rod  63   b . Finally, lower curtain  20  is adapted to receive an upper support rod  58   c , an intermediate drive rod  65  and a lower rod  63   c . Each of the aforementioned upper support rods  58   a ,  58   b  and  58   c  of the lower curtains is securely attached to the building structure by conventional means such as mounting brackets which are not shown in the figure for simplicity. It is in this manner that each of the lower curtains is supported by and suspending from the building structure. The weight of each of the lower rods  63   a ,  63   b  and  63   c  maintains each of the lower curtains in a stretched condition when suspended from a respective upper support rod. Each of the rods disposed in each of the lower curtains extends the full length of the lower curtain. Each of the aforementioned rods is preferably comprised of a high strength, lightweight, rigid material such as structural steel or aluminum. 
     Disposed between and connected to each adjacent pair of upper and lower curtains is a respective curtain support/drive mechanism. Thus, a first curtain support/drive mechanism  30  is disposed between and connected to upper curtains  18  and  22  and lower curtains  20  and  24  of the first and second curtain sections  12 ,  14 . Similarly, a second curtain support/drive mechanism  32  is disposed between and coupled to upper curtains  22  and  26  and lower curtains  24  and  28  of the second and third curtain sections  14 ,  16 . A similar curtain support/drive mechanism is connected to the outer end of each of the end curtain sections in a manner similar to that shown in  FIG. 1  and described below, although this is not shown in  FIG. 1  for simplicity. Although  FIG. 1  shows three curtain sections driven by two or more curtain support/drive mechanisms, a preferred embodiment of the present invention includes first and second curtain sections driven by an inner curtain support/drive mechanism located between the two curtain sections and by two outer curtain support/drive mechanisms each located on an outer end of one of the curtain sections. Individual curtain sections several hundred feet in length may be raised and lowered in this preferred embodiment to cover openings of 600′ and longer in length. 
     The second curtain support/drive mechanism  32  is shown in greater detail in the front perspective view of  FIG. 2 . Curtain support/drive mechanism  32  includes a generally vertically oriented guide member  44  connected near its upper end to the upper support member  40  by conventional connecting brackets which are not shown in the figure for simplicity. Similarly, the lower end of vertical guide member  44  is securely attached to the lower support member  42  by means of connecting brackets  68  and  70 .  FIG. 3  is a perspective view illustrating additional details of an upper drive assembly  100  attached to the vertical guide member  44 .  FIGS. 6 and 7  are lower perspective views showing additional details of the manner in which the upper drive assembly  100  is attached to and is displaced along the vertical guide member  44 . 
     Each of the curtain support/drive mechanisms includes an upper drive assembly and a lower drive assembly. The upper drive assembly includes an upper electrical drive motor  46 , while the lower drive assembly includes a lower electrical drive motor  48 . The upper drive assembly  100  further includes a first gearbox  52  connected to the upper electric drive motor  46 , while the lower drive assembly includes a second gearbox  54  connected to the lower electric drive motor  48 . The combination of the lower electrical drive motor  48  and the second gearbox  54  is coupled to the intermediate drive rods  64  and  66  of the lower curtains  24  and  28  by suitably connecting hardware which will now be described in detail in terms of the upper drive assembly  100  shown in  FIG. 4  because the construction and operation of the upper and lower drive assemblies is identical. 
     Connected to the first gearbox  52  and rotationally driven by the upper electric drive motor  46  is a drive shaft  102 . Attached to respective ends of the drive shaft  102  are a first drive sprocket  104  and a second drive sprocket, which is not shown in  FIG. 4  for simplicity. Disposed about the first drive sprocket  104  is a first endless chain  106 , while disposed about the second drive sprocket is a second endless chain  110 . Respectively disposed above and adjacent to the first drive sprocket  104  and the second drive sprocket are first and second driven sprockets  108  and  112 . Endless chains  106  and  110  also respectively engage the first and second driven sprockets  108  and  112 . Thus, rotation of the drive shaft  102  produces a corresponding rotation of the first drive sprocket  104  and the second drive sprocket giving rise to a corresponding rotation of the first and second driven sprockets  108  and  112 . The first and second driven sprockets  108 ,  112  are securely coupled together by means of the combination of a spacer tube  114  and first and second brass bushings  116  and  118 . Thus, the first and second driven sprockets  108  and  112  undergo the same rotational displacement. The first brass bushing  116  is securely connected to lower drive rod  60  of the upper curtain  22  of the second curtain section  14  as shown in  FIG. 2 . Similarly, the second brass bushing  118  is securely connected to the lower drive rod  62  of the upper curtain  26  of the third curtain section  16  as also shown in  FIG. 2 . Thus, the upper drive assembly  100  simultaneously rotationally displaces lower drive rods  60  and  62  in a first direction for rolling up the upper curtains and raising the two curtain sections, or in a second, opposed direction for unrolling the two upper curtains in unrolling the two adjacent curtain sections. A similar arrangement allows the lower drive assembly which includes a combination of lower electric drive motor  48  and second gearbox  54  to either roll-up the adjacent lower curtains  24  and  28  respectively onto intermediate drive rods  64  and  66 , or to unroll these curtains from the two intermediate drive rods in lowering the curtain sections. It should be noted that each of the upper and lower portions  24   a  and  24   b  of lower curtain  24  and each of the upper and lower portions  28   a  and  28   b  of lower curtain  28  are simultaneously rolled onto or unrolled from the lower drive rods  64  and  66 , respectively, during operation of the lower electric drive motor  48 . 
     While each of the lower curtains has been described and is illustrated as including an upper support rod, an intermediate drive rod and a lower rod, the present invention will work equally as well if the intermediate rod is omitted and the curtain is raised and lowered by means of its lower rod. Thus, for example, the present invention contemplates eliminating the intermediate drive rods  64 ,  65  and  66  of lower curtains  24 ,  20  and  28  and driving, i.e., raising and lowering, these curtains by means of a drive assembly connected to the lower rods  63   a ,  63   b  and  63   c  of these lower curtains. The advantage of the arrangement shown in  FIG. 2  where the drive arrangement is connected to an intermediate drive rod is that the upper and lower portions of each of these curtains are simultaneously rolled up on or unrolled from the rotating drive rod which reduces the time and the number of revolutions to roll-up or unroll the curtain. 
     As shown in the various figures, each drive assembly includes a carriage  146  connected to a drive motor as shown for the case of the upper electric drive motor  46  of the upper drive assembly  100 . A similar carriage arrangement is connected to the lower electric drive motor  48  and operates in a similar manner to allow the drive assembly to move upward and downward within the vertical guide member  44  as described in the following paragraphs. 
     Carriage  146  is in the form of a linear, elongated shaft of a high strength material such as structural steel and includes an inner shaft, or axle,  148  which extends the length of the carriage. Attached to a first end of shaft  148  is a first roller  150 , while attached to a second, opposed end of the shaft is a second roller  152 . Vertical guide member  44  includes a generally flat inner portion  44   c  and first and second edge flanges  44   a  and  44   b  disposed on opposed lateral edges thereof. Each of the edge flanges  44   a ,  44   b  extends outwardly from the flat inner portion  44   c  of the vertical guide member  44  and forms a channel which is adapted to receive and engage a respective roller of the carriage  146 . Thus, the first edge flange  44   a  is adapted to receive and engage the first roller  150 , while the second edge flange  44   b  is adapted to receive and engage the second roller  152 . Each of the rollers  150 ,  152  freely rotates on the carriage's shaft  148  and allows the carriage  146  to move vertically along the length of the vertical guide member  44 . Thus, as the lower drive rods  60  and  62  are rotationally displaced by the upper electric motor  46  of the upper drive assembly  100 , the combination of the upper electric motor and first gearbox  152  and associated hardware attached to the carriage  146  is free to move vertically up in the direction of arrow  154  and down in the direction of arrow  156  in  FIG. 6  along and within the vertical guide member  44 . This permits adjacent curtains to be rolled-up onto or unrolled from the two drive rods. 
     The larger weights of longer curtains apply increasingly larger torques to the curtain support and drive mechanism, particularly during raising of the curtain. Thus, if as shown in  FIG. 6 , lower drive rod  62  rotates in the direction of arrow  92 , the weight of the raised, or partially upraised, curtain will exert a torque counter to the direction of arrow  92 . The torque exerted by the curtain will urge the first roller  150  in a downward direction as shown by direction arrow  94  in  FIG. 7  and will urge the second roller  152  in an upward direction as shown by direction arrow  96  in the figure. The vertical guide member  44  opposes any displacement of the rollers out of the plane of the vertical guide member and ensures that the carriage  146  and the upper electric drive motor  46  attached thereto move only vertically during rolling up and unrolling of the attached curtains. In addition, the torque exerted along the lower drive rod  62  in the direction of arrow  98  shown in  FIG. 6  urges the carriage  46  and the upper electric drive motor  46  in a direction toward the vertical guide member  44 . In order to accommodate this latter torque, a third roller  160  shown in  FIG. 7  is attached to the carriage  146  by means of mounting bracket  158 . This third roller  160  facilitates displacement of the carriage  146  and upper electric drive motor  46  combination along the length of vertical guide member  44 . Third roller  160  thus counters the tendency of the aligned lower drive rods  60  and  62  to be rotationally displaced by the weight of the attached curtains and opposes any bending of carriage  146  and movement of the upper electric drive motor  46  toward the flat inner portion  44   c  of the vertical guide member  44 . 
     Referring to  FIG. 4 , there is shown a perspective view of the combination of first and second limit switches  72  and  74 . The first limit switch  72  is attached to a vertical pipe, or tube,  78  by means of a first coupling bracket  80 . Similarly, the second limit switch  74  is attached to the vertical pipe  78  by means of a second coupling bracket  82 . The vertical pipe  78  is disposed within and attached to the vertical guide member  44  by conventional means such as connecting brackets which are not shown for simplicity. The first limit switch  72  includes a first pivot arm  88  coupled to a first sensor housing  84 . Similarly, the second limit switch  74  includes a second pivot arm coupled to a second sensor housing  86 . Each of the first and second pivot arms  88 ,  90  is free to pivot upward or downward about its associated sensor housing. Thus, the first limit switch  72  provides an indication that the upper curtains  22  and  26  are in the full “DOWN” position. Another limit switch (not shown in the figures for simplicity) located in an upper portion of the roll-up curtain assembly provides an indication of the full “UP” position of the two upper curtains  22 ,  26 . The second limit switch  74  provides an indication of the full “UP” position of the two lower curtains  24 ,  28 . A third limit switch  76  mounted to a lower portion of the vertical pipe  78  as shown in  FIG. 2  provides an indication that the lower curtains  24  and  28  are in the full “DOWN” position. In the embodiment shown in the figures, the third limit switch  76  is engaged by the lower rod  63   a  of the second curtain section's lower curtain  24 . In the embodiment of the present invention where the lower curtain does not include upper and lower portions with the curtain's drive rod disposed on its lower edge, the third limit switch  76  would be engaged by the lower curtain's drive rod located on its lower edge. 
     Referring to  FIG. 5 , there is shown a combined schematic and block diagram of a control panel  50  coupled to a computer controller  138  for controlling the operation of the roll-up curtain assembly of the present invention. The left portion of the control panel  28  provides control of the first curtain section  12  shown in  FIG. 1 , while the right portion of the control panel controls the operation of the second curtain section  14 . A third portion of the control panel  50  provides control for the third curtain section  16  shown in  FIG. 1 , but this is not shown in  FIG. 5  for simplicity. Control panel  50  includes first and second toggle switches  130  and  132 . The first toggle switch  130  allows the user to select either an automatic or manual mode of operation, or to turn the controller for the first curtain section  12  “OFF”. When in the “AUTOMATIC” mode of operation, the operation of the first curtain section is under the control of the computer controller  138  which stores a pre-programmed operating program. The second toggle switch  132  is operable when the first toggle switch  130  is in the “MANUAL” mode of operation and allows for closing and opening of the first curtain section under the control of an operator. The right portion of the control panel  50  which controls operation of the second curtain section  14  similarly includes a first toggle switch  134  and a second toggle switch  136 . The first toggle switch  134  allows for the user to select between “AUTOMATIC” or “MANUAL” operation of the second curtain section, or to turn the curtain controller “OFF”. The second toggle switch  136  allows for manually controlling the position of the first curtain section  12  when the first toggle switch is in the “MANUAL” mode of operation. 
     While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.