High load operation of an industrial roll door

[0001] The present invention relates to the operation of heavy duty industrial roller doors. More specifically, the invention relates to rolling gates comprising a door leaf or curtain that can be rolled on a roller, provided with a drive system, tensioning elements, as well as means for preventing the movement of tensioning elements beyond a predetermined point in such a way as to prevent the movement of the curtain when the external load is operating.

Background Art [0002] Since the 1970s there has been a great demand for high speed industrial building gates. This applies to both internal openings and external walls, where the gate provides a partition between the various activities performed or prevents the movement of air currents and heat losses. Preferably, roller gates with flexible gate wings are used for this purpose, but stiffer constructions are also used, such as shutter gates with polymer or metal plates. These gates are rolled up on a top cylinder and can be fitted with additional elements such as transverse wind reinforcements on the gate wing to counteract wind load, weight balance system, tensioning system or the like. For safety reasons, rolling gates can also be equipped with edge protection, damage proofing devices, anti-fall protection as well as collision protection functions.

[0003] US 5,222 541 discloses an industrial roller door with a counterweight and tensioning system that balances the weight of the door leaf, and also, through the tensioning mechanism, acts downward stress on the closed door leaf to tension the door and avoid deformation by wind . It should be noted that this system operates with a constant pull force downwards, but does not include a frame sash lock in the down position. Either way, this invention primarily relates to the function of moving the gate.

[0004] US Patent 5,474,117 describes a locking mechanism for an up-rolled closure with horizontal slats. The lowest and highest slats have spring loaded pins that resist accidentally lifting this closure. The drawings of this patent show the gate locked at the bottom. It should be noted that similar solutions have been proposed earlier, but mainly as hitch assemblies.

[0005] A similar gate structure is disclosed in US Patent 5,632,317. The invention relates to an upward rolling door assembly with a number of embodiments including a movable barrier bar to minimize the deflection of the gate closing member or curtain due to wind or other forces pressure. However, this solution is very complex and contains expensive components. In addition, manual door locking is also provided for additional wind resistance.

[0006] US Patent 6,439,292 relates to a rolling up door with an anti-collision system that can automatically restore the door to working condition. In case the gate is not automatically restored, it can be restored manually. It should be noted that this patent provides a tear function in conjunction with a photocell to ensure safe operation when opening and closing the gate.

[0007] Although some of the above-mentioned solutions have some associated advantages, further improvements and / or alternative forms are always desirable.

SUMMARY OF THE INVENTION [0008] The object of the present invention is to provide an industrial gate that reduces the likelihood of intrusion and the occurrence of unwanted air current by substantially reducing the vertical gate flatulence.

[0009] Another object of the present invention is to provide an industrial gate that safely limits the edges of the gate plate in the guide channels, and thus prevents undesired penetration by substantially reducing the bulge of the industrial gate in the horizontal direction.

[0010] Still another object of the present invention is to provide an industrial gate that can withstand safely undesirable bulging in or out of the gate curtain in gate systems protecting machines. Inward bulging can be caused by people bumping into the gate. Bulging out can be caused by e.g. robot arms or goods that are scattered by a malfunctioning robot.

[0011] The present invention relates to an industrial rolling door operating under heavy loads. One embodiment of the present invention described herein provides an absolute stop inserted into the tensioning mechanism / counterweight in the gate. This absolute stop prevents movement of the counterweight spring or other tensioning elements beyond a certain point, thanks to which the gate curtain stays closed, even when it is exposed to strong winds or other external forces that cause a serious load on the gate.

[0012] These embodiments typically include a door curtain that can be wound on a roller that is provided with a drive system, tensioning means operating so that they extend when a load is applied to the curtain, a cable having a first end connected to the bottom of the curtain , where the cable extends from it, around the blocks, and the other end of the cable is connected to the cable drum, and an absolute stop to prevent the tensioning elements from moving beyond a predetermined point to prevent the closed curtain from moving when it is subjected to an external load.

[0013] Another embodiment includes an additional block and a split cord. This embodiment also includes a roller and cable drum provided with a drive system; the curtain of the gate to be wound on a roll and unrolled from a roll; tensioning elements operating in such a way that they move / stretch when a load is applied to the curtain; the first cable to be wound / unwound from the cable drum and has one end connected to it, the first cable extending from it above the first and second blocks, while the other end of the cable is connected to the reduction blocks; and a second cable with one end fixed, its other end extending above it over the reduction block and the third block, the other cable being connected to the bottom of the curtain.

Brief description of the drawings [0014] To better understand this invention, reference is made to the following description and the attached drawings, in which:

Fig. 1 shows a side elevational view of a prior art gate system;

Fig. 2 is a side elevational view of the gate system with an absolute stop according to the present invention;

Fig. 3 is a side view of the prior art gate system with an alternative spring position;

Fig. 4 is a side view of a gate system with a mechanical stop and an alternative spring position in accordance with the present invention;

Fig. 5 is a side view of a gate system with a spring limiter according to the present invention;

Fig. 6 is a side view of a gate system with a spring stop in an alternative position according to the present invention;

Fig. 7 is a side view of a gate system with a reduction block;

Fig. 7A is a side view of the door system shown in Fig. 7, where the cable drum is smaller than the top roller;

Fig. 8 is a side view of the gate system, with a reduction block and mechanical stop; Fig. 8A is a side view of the gate system shown in Fig. 8 where the cable drum is smaller than the top roller;

Fig. 9 is a side view of the gate system with a reduction block and an alternative spring position;

Fig. 9A is a side view of the door system shown in Fig. 9 where the cable drum is smaller than the top roller;

Fig. 10 is a side view of a gate system, with a reduction block, mechanical stop, and also an alternative position of the spring according to the invention;

Fig. 10A is a side view of the gate system shown in Fig. 10 where the cable drum is smaller than the top roller;

Fig. 11 is a side view of the gate system, with a reduction block and spring stop; Fig. 11A is a side view of the gate system shown in Fig. 11 where the cable drum is smaller than the upper roller;

Fig. 12 is a side view of the gate system with the reduction block and spring stop in an alternative position;

Fig. 12A is a side view of the gate system shown in Fig. 12 where the cable drum is smaller than the upper roller;

Fig. 13 is a side view of a gate system with block and absolute electromechanical stop in accordance with the present invention;

Fig. 14 is a side view of a gate system with block and mechanical stop in accordance with the present invention;

Fig. 15 is a side view of a gate system with block and mechanical stop according to the present invention;

-4Fig. 16 is a side view of a gate system, with a block and balance mechanical stop, in accordance with the present invention;

Fig. 17 is a side view of a gate system with block and electro-mechanical stop according to the present invention;

Fig. 18 is a side view of a gate system with a block and mechanical spring-loaded absolute stop according to the present invention;

Fig. 19 is a side view of a gate system with block and absolute stop with a pneumatic piston in accordance with the present invention;

Fig. 20 is a side view of a gate system with a block and an electro-mechanical stop with a compression spring according to the present invention;

Fig. 21 is a side view of a gate system with a connecting block and a drum of truncated cone; while

Fig. 22 is a side view of a gate system with a connector block and a drum of truncated cone.

Detailed Description of Preferred Embodiments [0015] Figs. 1 and 3 show a side view of prior art roller doors with standard tensioning and balancing systems. As can be seen in Fig. 1, the upper roller 1 and cable drum 7 are rotatably mounted above the gate and are provided with a drive system (not shown), with the gate curtain (gate plate) 2, operating in such a way that it can be wound and unwinding around the top roller 1. In addition, the lower beam 3 is attached to the lower end of the gate curtain 2. A cable 6 was used, which has one end attached to the bottom beam 3, while its other end is attached to the cable drum 7. The cable 6 extends around the stationary block 4 and around block 12 loaded by the bias tension spring 5. This tensile safety spring 5 can alternatively be located at the top of the gate wall opening, as illustrated in Fig. 3. In each case, this spring 5 extends when the curtain 2 is loaded, for example by wind or other external forces. Nevertheless, in the case of the standard door systems shown in Fig. 1 and 3, the extension / extension of the tension safety spring 5 is unlimited (except for the internal force of the spring). Unfortunately, this can lead to unwanted rising of the beam 3 in high winds or when other external forces act on the curtain 2 of the door.

[0016] Preferably, the gate tensioning and balancing system according to the present invention solves the above-described problems, while avoiding the drawbacks of prior art gate systems. It is understood that the cord 6 may be in the form of a wire, belt, chain, cord, wire or other solutions without departing from the scope of the present invention. Further solutions may alternatively be used for the upper roller 1, including, but without imposing any restrictions, disks located on each side of the gate, collecting rollers of a suitable size or other elements known to those skilled in the art.

[0017] As shown in Fig. 2, one embodiment of this invention includes a door curtain 2 suitable for winding around the top roller 1, which is located above the door frame and is provided with a drive system (not shown). The lower beam 3 is attached to the end of the curtain

-52. In addition, a cable 6 has been used which has one end attached to the bottom beam 3, the other end being attached to the cable drum 7. The cord 6 extends around the stationary blocks 4 and around the movable block 12 loaded with a tension spring 5. This tension spring 5 extends when the curtain 2 is loaded.

[0018] Although the spring extension is unlimited in a standard tensioning system, the present invention, as shown in Fig. 2, provides for a rigid extension limiter or mechanical stop ("absolute stop") 9A and 9B to prevent tension displacement safety spring 5 beyond a certain point. Advantageously, this prevents the lower beam 3 from rising when strong winds or other external forces cause a heavy load on the curtain 2 of the door. This absolute stop 9 may include, for example, a first member 9A, which during spring expansion is engaged with the second member 9B attached to block 12. The mechanical stop mechanisms 9 described in this document resist not only wind, but also significant loads caused by air conditioning, fans and the like, or vertical forces acting on the curtain 2 of the gate from, for example, an intruder. In addition, means may be used to fix the lower beam 3 in a closed position, for example using mechanical or electromechanical locks.

[0019] The limitation of the elongation of the tension spring 5 ensures the tension between the lower beam 3 and the upper roller 1. This in turn prevents the external load caused by wind or other forces from lifting the lower beam 3 because its movement is limited by the rope system 6 until the upper roller 1 moves. The movement of the upper roller 1 can be prevented by means of the motor brake, or in extreme conditions by the addition of a supplementary locking device. In addition, it is noted that the elongation of the cable 6 under load may reduce the efficiency of the device, and therefore the cable 6 should be carefully selected so as to minimize its unwanted elongation. Furthermore, those skilled in the art will be aware that the springs 5 ​​and 13 may in fact be a combination of two or more springs (see, for example, the springs 5 ​​in Fig. 15) that can be positioned in various positions including attachment to the top or bottom part of the door frame or inside the top roller. The springs 5 ​​may furthermore be located on one or both sides of the gate, and may also be connected in parallel or in series. Furthermore, those skilled in the art will understand that the springs 5 ​​and 13 may be made of rubber cables that are connected in parallel or formed into loops. Similarly, a pneumatic or gas spring, or a hydraulic spring can replace springs 5 ​​and 13 in each embodiment of the present invention. [0020] It will be understood by those skilled in the art that the curtain of the gate 2 may comprise coated textile material, flexible or rigid slats or tiles, or any other material that can be rolled. In addition, the door curtain can be flexible in all directions, or flexible only in the rolling direction, while it is made essentially non-bending in other directions by means of stiffening members attached to this curtain 2 of the gate, or by using other appropriate means . In addition, instead of vertical, the gate can be horizontal and sideways, or it can even be installed at an angle. It should also be noted that the lower beam 3 does not need to be used, in which case the cable (s) 6 may be attached to the lower corners of the curtain of the gate 2.

[0021] As described above, the present invention provides some advantages over the concepts proposed in the prior art for preventing the gate from rising in high wind conditions or when other forces act on the curtain 2 of the gate. For example, one prior art gate system uses significant tensioning through the tensioning / balancing system in open positions, but this is considered undesirable because it introduces instability into the mechanical gate systems. It is further noted that locking systems have been used, but they are disadvantageous due to the additional costs and their complexity. On the other hand, the benefits provided by the door system of the present invention include high reliability, low cost, and especially the flexibility of providing collision protection.

[0022] It should be noted that the efforts made in the prior art to develop a collision protection function for a gate with a strong tensioning system have proved to be problematic. For example, in one of the state of the art projects, in the so-called "Posidrive" system, the inclusion of the collision protection function is limited due to the requirement that the lower beam 3 must be rigidly connected to the drive system.

[0023] In contrast, the structure according to the present invention provides a strong tension by pulling down only in the closed position of the gate. This means that in intermediate positions of the gate's movement, the lower beam 3 is connected to the drive system with less stress. (Note, however, that springs 5 ​​or 13 always provide some tension on the curtain 2). Accordingly, the use of the collision protection system in connection with the present invention is simplified by this more flexible coupling of the lower beam 3 to the drive system.

[0024] One example of a collision protection assembly allows the gate curtain to be released from guide channels in which the gate curtain is raised and lowered after a strong external force such as being hit by a vehicle or other moving object. Collision protection assemblies do not deflate the gate after being exposed to strong wind conditions or forces related to, for example, burglar attack. It should be noted that collision protection systems typically work best when the gate is in the "almost open" position (when most collisions occur) and are generally less effective when the gate reaches the closed position. Collision protection assemblies may include various mechanical or electromechanical designs, including, but not limited to, a pin that breaks at a certain threshold stress, a sensor connected to the release assembly, or a spring loaded system. The collision protection assembly is optionally used in each of the embodiments described herein.

[0025] Figs. 4-6 illustrate further variations of the present invention. For example, Fig. 4 shows an embodiment in which the extendable safety spring 5 is located near the top of the door frame instead of the bottom. Figures 5 and 6 show further variants in which the pressure safety spring 13 was used instead of the pressure safety spring 5 as shown in Fig. 1. This safety pressure spring 13 can be positioned either running downwards as shown in Fig. 5 or as running upwards as shown in Fig. 6. In each of these cases, the safety pressure spring 13 acts as a stop. absolute when this spring 13 remains completely

-7ściśnięta. It should be noted that for each of the embodiments shown in Fig. 4 6, limiting the extension or compression of the spring 5 or 13 preferably prevents the lower beam 3 from rising when external forces act on the curtain 2 of the door. The compression spring elements depicted in these drawings may also represent a spring element consisting of compression springs in series or parallel systems.

[0026] Figs. 7-12 show further variants of this invention in which an additional block 8 ("reduction block") and a split line 6 are used. It should be noted that each of Figs. 7A, 8A, 9A, 10A, 11A and 12A shows a slight change compared to Figs. 7, 8 etc., where the cable drum 7 has a smaller diameter than the upper roll 1. The split cable arrangement 6 provides the advantage of reducing the downward pulling force and enabling the use of a reduced cable drum diameter, which results in both economical and space saving considerations. For example, in the embodiment shown in Fig. 7, a door curtain 2 is used which has a lower beam 3 and is wound around the upper roller 1. The first part of the cable 6 has one end connected to the cable drum 7 and runs around the block 12 loaded with a tension spring 5 and then around the stationary block 4, while the other end of the cable is connected to the reducing block 8. The other part of the cable 6 has one end attached to bottom beam 3, and runs from it around the fixed block 4 and around the reducing block 8, while the other end of the cable is attached near the bottom of the door frame. The extension safety spring 5 can alternatively be located at the top of the door frame, as shown in Fig. 9.

[0027] In addition, the elongation stop 9 can additionally be used as shown in Figs. 8 and 10. Alternatively, the spring 13 with the stop being used can be used as shown in Figs. 11 and 12. Thus , in addition to providing the advantage of reducing downward tension force and cable drum diameter, the variants shown in Fig. 8 and 10-12, in which the expansion or compression of the spring 5 or 13 has been limited, provide another advantage in preventing the curtain 2 from moving during high load operation. The elongation stop 9 can be equipped with a lock and release mechanism 10, e.g. an electromagnet, as shown in Figs. 13, 17 and 20, which can be actuated by a sensor or other suitable elements. In each of the embodiments shown in Figs. 2, 4, 8 and 10, limiting the elongation of the extension spring 5 prevents the lower beam 3 from rising when external forces act on the curtain 2 of the door. In the other embodiments mentioned herein, similar locking and release mechanisms operate with similar effect. In addition, the examples cited herein are given as examples and are not intended to limit the scope of the present invention, as other locking and release mechanisms can be easily identified as being suitable for use in this case by those skilled in the art.

[0028] It will be understood by those skilled in the art that many different combinations of springs or tensioning elements, in combination with collision protection elements or other securing elements, can be used in the constructions of the present invention. For example, Fig. 14 shows a gate operating under heavy load, similar to that of Fig. 2,

- whereby the elongation stop has been replaced by a section of chain, cable, cord or the like 11, which limits the movement of the tension spring 5. As a safety function, chain 11 can be used in combination with the "weak link" mechanism (not illustrated) to protect the gate components in the event of a collision or other heavy load incident.

[0029] Fig. 15 shows a further variant of the high-load gate illustrated in Fig. 2, further comprising a second safety tension spring 5, as well as a mechanical extension stop 9A & 9B. These two springs are arranged in series and both resist movement of the gate, while the mechanical stop 9A and 9B prevents movement of the springs 5 ​​and ultimately the curtain 2 of the gate beyond a predetermined point.

[0030] Fig. 16 shows a gate under high load, which is almost identical to that of Fig. 15, the main difference being that the weight 16 has replaced the second spring 5. The weight 16 works together with the spring 5 to preventing the curtain of the gate 2 from rising. In addition, the weight of the weight can be optimized by specialists in this field for the needs of a particular application.

[0031] Fig. 17 is another embodiment of a gate operating at high load according to the present invention. The embodiment shown in Fig. 17 combines the electromechanical locking and release mechanism 10, shown in the embodiment according to Fig. 13, and used in conjunction with the double spring 5 and the mechanical stop 9A and 9B shown in Fig. 15. In this embodiment, the movement of the two springs 5 ​​is limited by the mechanical stop 9A and 9B until an event occurs, which releases this electromechanical locking mechanism 10, whereby part 9A of the mechanical stop is released and the force acting on the curtain 2 of the gate is released acted on springs 5.

[0032] Fig. 18 shows yet another embodiment of the present invention, using a pressure safety spring 13 and a tension safety spring 5. This pressure safety spring 13 cooperates with a mechanical stop 9A and 9B to limit the movement of the door curtain 2. Then, the safety pressure spring 13 and the extendable safety spring 5 work in such a way as to slow down or prevent the gate curtain 2 from moving within a certain movement limit. Fig. 19 shows a system almost identical to that of Fig. 18, except that the pressure safety spring 13 has been replaced by a pneumatic or gas spring 15. As illustrated in Fig. 19, the gas spring 15 may include one or more pressure valves 14 that can be used to assist in limiting the movement of the gate curtain 2. A similar functional feature using valves can be obtained by replacing this pneumatic spring with a hydraulic spring system.

[0033] A further embodiment of the present invention is shown in Fig. 20, it comprises a safety pressure spring 13 used in conjunction with the mechanical stop 9A and the electromechanical locking and release mechanism 10.

[0034] Yet another embodiment is shown in Fig. 21. Fig. 21 shows a gate system 100 including downward pulling and stretching systems. This system includes a compression safety spring or balance spring 101, a tension safety spring or

Downwardly extending spring 102, connecting block 103, door leaf roller 104, frusto-cone-shaped drum 105, first cable 107, and second cable 108. Alternatively, this system may also include a spring stop 106 that limits the range of the operating spring down the pull spring 102.

[0035] In one preferred embodiment, the truncated cone cord 105 is half the diameter (D / 2) of the gate curtain roll 104. In this embodiment, the gate curtain roll 104 and truncated cone drum 105 rotate at the same speed and in the same direction. During the opening and closing operations, the diameter of the working part of the cable drum 105 having a frustoconical shape, i.e. the part on which the first cable 107 acts at one point in time, is reduced in a proportion similar to the change in the thickness of the door leaf roller 104. This means that when the door curtain 110 is lowered, the thickness of the door curtain roller 104 is reduced. At the same time, the frustoconical drum 105 of the cord collects the first cord 107, and as more and more cord is collected, the cord wound on the frustum-conical drum 105 of the cord is wrapped on a portion having a smaller diameter of this frustum-conical drum 105 of the cord. This results in the connecting block only moving approximately at the distance of the gate curtain 110 during the opening or closing operations. In addition, due to the fact that this system is effectively balanced by the truncated cone-shaped cable drum 105, there is little or no displacement of the downwardly extending tension spring 102, while there is a relatively constant tension acting on both the curtain 110 of the gate as well as a truncated cone 105 cable drum via the first and second cables 107 and 108, respectively.

[0036] The spring stopper 106 limits the extension of the downwardly extending tension spring 102. A drive unit (not shown) and a second cable 108 keep the gate curtain 110 stretched and pull this gate curtain 110 downward with more force than would be possible with due to the downwardly extending spring 102 itself. In this way, the door can remain closed, even when exposed to strong winds. When it is known that high wind applications are envisaged, the spring stop 106 should be adjusted with a minimum gap to prevent blockage and excessive stretching of the ropes.

[0037] For some applications, it may be desirable to use a truncated cone-shaped cable drum (105) that has a diameter larger than D / 2 of the gate curtain roll 104. This configuration will cause the downwardly extending extension spring 102 to be limited by the spring stopper 106 when the door curtain 110 is in the closed position. When it is in this position, the lower beam will therefore be less susceptible to collision with, for example, a vehicle, because the lower beams and the curtain of the gate can leave the side guide tracks. Due to the above, it is possible to easily apply typical picking systems and the function of self-adjusting the lower beam. Also when the spring stopper 106 acts on the downwardly extending tension spring 102, the door curtain 110 is pushed down by the drive unit via the first and second cables.

[0038] Other options that can be included in this configuration include the use of additional blocks to limit the travel range of the connector block 103, which in turn would allow

-10 to increase the drum diameter of 105 cables. Additional blocks would also limit the extension of the balance spring 101.

[0039] Such a system as described with reference to Fig. 21 allows the gate to be operated with any tension and a downward force acting, which allows the spring size to be optimized for a given application. Preferably, this system requires only a single cable drum on each side of the gate, effective for both supporting and balancing the gate. Moreover, since the system is substantially balanced, the size of the downwardly extending spring 102 can be reduced and its displacement limited to substantially zero. In addition, when used in conjunction with the spring stop 106 and where the drive unit cannot move backwards when not in use, the gate is effectively locked, thereby increasing the security of the gate. Finally, this configuration uses the torque from the drive unit to both pull down and pull up the door curtain during the entire opening and closing operations, and therefore it is suitable for applications where there is very strong wind . Another embodiment is shown in Fig. 22. Although it has been illustrated as two separate wheels, in practice the truncated cone-shaped cable drum 105 and the gate roller 104 are in fact on the same axis and are shown as separate in Fig. 22 to facilitate interpretation of the drawings. The gate roller 104 houses the gate curtain 110, which is connected to the first cable 108. The first cable 108 is connected to the truncated cone 105 of the inca drum via three blocks 116. At least one combination of three blocks is connected to a safety bias spring or downwardly extending spring 102. This downward extending spring can optionally be connected to a spring stopper 106, which can optionally include an adjustable gap. The first cord 108 is connected to the second cord 107 through a wire connector 115. The second cord 107 passes through at least one block 118, and preferably a combination of three blocks, and connects to a balance spring or pressure spring 101.

[0040] The gate system 111 shown in Fig. 22 has a tensioning system separate from the balance system. The balancing portion of system 111 is the portion extending from the conduit connector 115 to the balance spring 101, while the tensioning system is the portion of the system 111 extending from the curtain 110 of the gate to the conduit 115. The diameter of the gate roller 104 depends on the thickness of the gate curtain 110 and varies depending on the position of the gate, from the maximum diameter when the gate is fully open to the minimum diameter when the gate is completely closed.

[0041] When the door curtain 110 is rolled up and down, the frustoconical shape of the cable drum 105 compensates for changes in the diameter of the door roller 104, allowing the forces acting on the door curtain 110 to be balanced. Because the gate roller 104 and truncated cone drum 105 have the same axis, they rotate at the same speed. The use of the frustoconical shape in the cable drum 105 compensates for changes in the rotational speed and torque at which the cable drum 105 and the gate roller 104 operate when engaged during the operation of raising or lowering the gate curtain 110. Slight size differences between the truncated cone drum 105 of the cable and the gate rollers 104 are compensated by the downwardly extending tension spring 102. Moreover, in at least one embodiment, the pitch coefficient of the truncated cone drum 105 of the cord is designed to be higher than the pitch coefficient of the gate roller 104.

[0042] The tensile force F1 acts due to the downwardly extending tension spring 102, and can also be optimized for a particular installation. The downwardly extending extension spring 102 resists stretching of the door curtain 110 in the event of load due to high winds, and also prevents the door curtain 110 from moving vertically due to such loads. The spring stopper 106 can be used to prevent the extension of the downwardly extending tension spring 102 and further prevents the gate curtain 110 from moving under stress, while the downwardly extending extension spring 102 alone would not prevent the gate curtain 110 from moving. Furthermore, the gap between the spring stopper 106 and the downwardly extending tension spring 102 can be optimized in such a way that the spring operates when operating the gate, and thus always provides a certain downward pulling force, F1. In addition, such an adjustable gap can be adjusted such that when the gate is in the closed position, a zero gap is available, thereby preventing any movement of the gate plate 110. In some embodiments, the door curtain 110 will better withstand load conditions as a result of using the lower beam 120.

[0043] The tensile force F1 does not affect the balance of the system. When the curtain 110 of the gate is opened or closed, the diameter of the gate roller 104 and the frusto-conical drum 105 of the cord remain approximately the same. The moment resulting from F1 on the frusto-conical cable drum 105 will therefore be almost identical, but the opposite sign than the moment caused by the action of force F4 on the roller 104 of the gate, resulting in a system close to balance. Any differences are compensated by the balancing spring 101.

[0044] The force F3 acting on the frustoconical cable drum 105 is almost equal to the force F4 acting on the door roller 104. The force F2 with which the balance spring 102 operates is approximately equal to the force caused by% of the weight of the gate curtain 110 and the bottom beam 120 when the system is in a balanced state. While the curtain 110 of the gate moves downwards, the force F4 increases but is balanced by the counteracting increase F2 with which the balancing spring operates. In this way, the system remains balanced during operation, regardless of whether it is moving up or down.

[0045] In this way, the above-described examples, objects and advantages of the present invention are realized, although although preferred embodiments have been disclosed and described in detail herein, the scope and objectives should not be limited by them; on the contrary, the scope of the invention should be determined by the scope of the appended claims.