Patent Application
20080041536
The present invention relates to the high load operation of an industrial roll door. More specifically, the invention relates to a roll door comprising a door blade, or curtain, which is windable about a roll that is provided with a drive system, a biasing means, and means for preventing the biasing means from traveling beyond a predetermined point, so to prevent movement of the curtain when an external load is applied.
Since the 1970's there has been a great need to use rapidly moving doors in buildings for industrial use. This applies to openings indoors as well as in external walls, where the door provides shielding between different activities or prevents drafts and heat losses. Presently, rolling doors with flexible door leaves are used for this purpose, but also more rigid constructions like slatted doors with polymeric or metallic lamellae are used. These doors are rolled up on an overhead drive cylinder and can be provided with additional elements like transverse wind reinforcements on the door leaf to counteract wind load, a weight balance system, tensioning system, windows or the like. For safety reasons, rolling doors can be further provided with safety edge protection, failsafe devices, drop protection, and crash safety functions.
U.S. Pat. No. 5,222,541 teaches a roll-up industrial door with a counter-balancing and tensioning system which counter-balances the weight of the door panel and, through a biasing mechanism, applies a downward tension to the closed door panel to stretch the panel and resist wind deflection. It is noted that the system operates with constant force in the pull-down direction, but contains no locking of the door leaf in the lower position. In any case, the invention is primarily directed to a break-away function.
U.S. Pat. No. 5,474,117 describes a locking mechanism for a roll-up closure with horizontal slats. The lowermost and uppermost slats carry spring-biased pins which resist unintentional lifting of the closure. The drawings of this patent shows a door locked at the bottom. It is noted that similar solutions have been previously proposed, but mainly as catching devices.
A related door construction is disclosed in U.S. Pat. No. 5,632,317. The invention is a roll-up door assembly with a number of embodiments including a moveable barrier bar to minimize deflection of the door closure member, or curtain, due to wind or other pressure generating forces. However, this solution is very complex and contains expensive elements. In addition, manual locking of the door is also provided for added wind resistance.
U.S. Pat. No. 6,439,292 is a roll-up door with a crash safety system that can automatically return the door to an operational condition. In the event that the door is not automatically restored to operation, it can be restored manually. It is noted that this patent presents a break-away function in combination with a photocell for safe operation during opening and closing of the door.
While some of the foregoing references have certain attendant advantages, further improvements and/or alternative forms, are always desirable.
It is an object of the present invention to provide an industrial door that reduces the potential for trespassing and unwanted draft by substantially reducing the bulging of the industrial door in the vertical direction.
It is another object of the present invention to provide an industrial door that safely restricts the door blade edges to guide channels, and thereby prevents unwanted trespassing by substantially reducing the bulging of the industrial door in the horizontal direction.
It is another object of the present invention to provide an industrial an industrial door that safely can withstand unwanted inwards or outwards bulging of the door curtain in machine protection door installations. The inwards bulging may be caused by people falling into the door. The outwards bulging may be caused by e.g., robot arms or by goods that are thrown around by a runaway robot.
The present invention provides a high load operation industrial roll door. One embodiment of the present invention described herein provides a positive stop inserted into a tensioning/counter-balance mechanism of the door. This positive stop prevents a counterbalance spring or other biasing means from moving beyond a certain point, thereby keeping the door curtain in a closed position when subjected to high winds or other external forces that cause heavy loading on the door.
These embodiments typically comprises a door curtain which is windable about a roll that is provided with a drive system, a biasing means operable to stretch when a load is applied to the curtain, a cable having a first end connected to the bottom of the curtain, the cable running therefrom over pulleys, a second end of the cable being connected to a cable drum, and a positive stop preventing the biasing means from traveling beyond a predetermined point, so to prevent movement of the closed curtain when an external load is applied thereto.
Another embodiment of the present invention includes an extra pulley and a divided cable. This embodiment also includes a roll and cable drum provided with a drive system; a door curtain to be wound upon the roll and unwound from the roll; a biasing means operable to travel/stretch when a load is applied to the curtain; a first cable to be wound/unwound from the cable drum and having one end connected thereto, the first cable running therefrom over first and second pulleys and the other cable end being connected to a reduction pulley; and a second cable with one end being fixed, the second cable running therefrom over the reduction pulley and a third pulley, and the other cable end being connected to the bottom of the curtain.
For a more complete understanding of the invention, reference is made to the following description and accompanying drawings, in which:
Advantageously, the door tensioning and balance system according to the present invention provides a solution to the above-described problems while avoiding the drawbacks of the prior art door systems. It is appreciated that the cable 6 could be in the form of a wire, a belt, a chain, a cord, a rope, or other configurations without departing from the scope of the present invention. Further alternatives to the top roll 1 may be employed including but not limited to disks located on each side of the door, truss rolls of a desired size or other means known to those of skill in the art.
As shown in
Whereas spring elongation is unrestricted in a standard tensioning system, the present invention, as shown in
Restricting the elongation of the tension resistant spring 5 provides tension between the bottom beam 3 and the top roll 1. This, in turn, prevents external loading of wind or other forces from raising the bottom beam 3, since movement thereof is restricted via the cabling 6, as long as the top roll 1 does not move. The movement of top roll 1 can be prevented by a motor brake, or in extreme conditions, by adding a supplemental locking device. Incidentally, it is noted that cable 6 elongation under loading can reduce the effectiveness of the device, and that, therefore, care should be taken in selecting the cable 6 so to minimize unwanted elongation. Further, one of skill in the art will appreciate that the springs 5 and 13 could in fact be a combination of two or more springs (see for example springs 5 in
Those of skill in the art will understand that the door curtain 2 can comprise coated fabrics, polymeric film, flexible or rigid slats or lamellae, or any other materials that can be rolled up. In addition, the door curtain can be flexible in all directions, or flexible only in the rolling direction while being made substantially inflexible in other directions via stiffing members fastened to the door curtain 2, or via other suitable means. Additionally, instead of being vertical, the door can be horizontal so to operate sideways, or can even be installed on an angle. Note also that the bottom beam 3 need not be included, in which case the cable(s) 6 can be fixed to the bottom corners of the door curtain 2.
As described above, the present invention provides certain advantages over prior proposals for preventing the raising of the door in high wind conditions or when other forces act on the door curtain 2. For example, one prior art door system provides high amounts of tension from the tension/balance system at open positions, but this is considered undesirable since this introduces instability to mechanical door systems. It is further noted that locking systems have been employed, but are disadvantaged by additional costs and complexity. The advantages provided by the door system according to the present invention, on the other hand, include high reliability, low cost, and, in particular, the flexibility to provide crash functions.
It is noted that prior art attempts at designing an anti-crash function for a door with a high pulldown tensioning system have proved problematic. For example, one prior art door design, a so-called “Posidrive” system, limits the inclusion of a anti-crash function, due to a requirement that the bottom beam 3 be rigidly connected to the drive system.
The design of the present invention, on the other hand, provides the higher pull down tension only at the closed position of the door. This means that at intermediate positions of door movement, the bottom beam 3 is less tensely connected to the drive system. (Note, however, that the springs 5 or 13 always provides some tensioning of the curtain 2). Accordingly, the use of an anti-crash system in conjunction with the present invention is simplified by this more flexible coupling of the bottom beam 3 to the drive system.
One example of an anti-crash device releases the door curtain from the guide channels, in which the door curtain is raised and lowered, upon application of a high external force, such as when hit by a vehicle or other moving object. Anti-crash devices do not release the door when subjected to high wind conditions or by forces applied by burglar attacks, for example. It is noted that the anti-crash systems typically operate best when the door is in the “almost open” position (where most collisions occur), and are generally less effective as the door reaches the closed position. Anti-crash devices may include a variety of mechanical or electromechanical designs, including but not limited to a pin that is broken at some threshold pressure, a sensor connected to a release device, or a spring-loaded arrangement. An anti-crash device is optionally included in each of the embodiments described herein.
In addition, an elongation stopper 9 can be further included as shown in
It will be appreciated by those of skill in the art that a variety of combinations of the springs or biasing means in combination with anti-crash or other safety means can be incorporated into the designs of the present invention. For example
A further embodiment of the present invention is shown in
Yet a further example of the present invention is shown in
In one preferable embodiment the frusto-conical cable drum 105 is half the diameter (D/2) of the door curtain roll 104. In this embodiment the door curtain roll 104 and the frusto-conical cable drum 105 rotate at the same speed and in the same direction. During the opening and closing operations, the diameter of the effective portion of the frusto-conical cable drum 105 i.e., that portion upon which the first cable 107 is acting at one point in time, is reduced at a rate similar to the change in thickness of the door blade roll 104. That is as the door curtain 110 is lowered, the thickness of the door curtain roll 104 is reduced. At the same time, the frusto-conical cable drum 105 takes up the first cable 107, and as more cable is taken up the cable spooled onto the frusto-conical cable drum 105 is wrapped at a successively smaller diameter portion of the frusto-conical cable drum 105. This results in connection pulley only moving approximately ½ the distance of the door curtain 110, during an opening or closing operation. In addition, because the system is effectively balanced by the frusto-conical cable drum 105, there is little or no movement in the pull down spring 102, while there is relatively constant pressure being applied to both the door curtain 110 and the frusto-conical cable drum 105 by the first and second cables 107 and 108, respectively.
The spring stopper 106 limits the elongation of the pull down spring 102. The drive unit (not shown) and second cable 108 keep the door curtain 110 stretched and pull down the door curtain 110 with greater tension that would be possible by the pull down spring 102 would be capable of alone. Thus the door can be closed even when subjected to high winds. When known to be used in high wind applications, the spring stopper 106 should be adjusted with a minimal gap to prevent jams and overstretching of the cables.
In certain applications it may be desirable to utilize a frusto-conical cable drum (105) that has a diameter of greater than D/2 of the door curtain roll 104. Such a configuration will result in the pull down spring 102 being restricted by the spring stopper 106 when the door curtain 110 is in the closed position. When in this position, the bottom beam will therefore be less vulnerable to a collision with, for instance, a vehicle since the bottom beams and door curtain can leave the side guide tracks. Accordingly, typical bottom beam break away systems and self-repairing functions known in the art may readily be implemented. Also, when the spring stopper 106 is acting on pull down spring 102, the door curtain 110 is being forced down by the drive unit through the first and second cables.
Other options that may be included in this configuration include the use of additional pulleys to limit the amount of travel of connection pulley 103, which in turn would allow the cable drum 105 diameter to be increased. Extra pulleys would also limit the elongation of balance spring 101.
Such a system as described in connection with
The door system 111 shown in
As the door curtain 110 is rolled up or down, the frusto-conical shape of the cable drum 105 accounts for the change in diameter of the door roll 104 allowing for a balancing of the forces applied to the door curtain 110. Because the door roll 104 and the frusto-conical cable drum 105 are on the same axis, they rotate at the same speed. Use of the frusto-conical shape of the cable drum 105 accounts for the changing rotational speed and torque that are applied by the cable drum 105 and the door roll 104 when engaged in either a raising or lowering operation of the door curtain 110. Small variations in difference in size between the frusto-conical cable drum 105 and the door roll 104 are accommodated by the pull down spring 102. Further, in at least one embodiment the pitch ratio of the frusto-conical cable drum 105 is designed to be higher than the pitch ration of the door roll 104.
A stretch force F1 is applied by the pull down spring 102, and may be optimized for a particular installation. The pull down spring 102 resists stretching of the door curtain 110 when experiencing high wind loads, and prevents the door curtain 110 from moving in the vertical direction when under such loads. The spring stopper 106 may be used to prevent the over extension of the pull down spring 102, and further prevent movement of the door curtain 110 when under extreme conditions, where the pull down spring 102 alone would not prevent movement of the door curtain 110. Further, the gap between the spring stopper 106 and the pull down spring 102 may be optimized so that the spring is effective throughout the operation of the door, thereby always providing some pull down force, F1. Still further, the adjustable gap may be set so that when the door is in a closed position zero gap is available, thereby preventing any movement of the door blade 110. In some embodiments, the door curtain 110 will better withstand high loading conditions by use of a bottom beam 120.
The stretch force F1 does not affect the balance of the system. As the door curtain 110 is opened or closed the diameter of the door roll 104 and the frusto-conical cable drum 105 remains approximately the same. Torque from F1 on the frusto-conical cable drum 105 will thus be nearly identical but of the opposite sign as the torque applied by the force F4 on the door roll 104, thus resulting in a near balanced system. Any difference is accounted for with the balance spring 101.
The force F3 on the frusto-conical cable drum 105 is approximately equal to the force F4 on the door roll 104. Force F2 imparted by the balancing spring 102 is approximately equal to the force created by ½ of the weight of the door curtain 110 and bottom beam 120, when the system is in a balanced state. While the door curtain 110 is moving in the downward direction, force F4 increases, but is balanced by a counteracting increase in F2 imparted by the balance spring. Thus the system remains balanced throughout operation, whether moving in the upward or downward directions.
Thus by the foregoing examples, the objects and advantages of the present invention are realized, and although preferred embodiments have been disclosed and described in detail herein, its scope and objects should not be limited thereby; rather its scope should be determined by that of the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US05/14700 | 5/2/2005 | WO | 7/12/2007 |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10838783 | May 2004 | US |
| Child | 11587226 | Jul 2007 | US |
