Methods for landing a kite system, and kite system

Abstract

A method for landing a kite system (23), the kite system (23) comprising a kite (14) and a control pod (25). The kite (14) is held on the control pod (25) via a line system (24). The control pod (25) is held on a ground attachment point (16, 44) via a tether (15) during normal operation of the kite system (23). The sail surface of the kite (14) spreads over a first kite section (40) and a second kite section (41). A connection (36) present in the sail surface between the first kite section (40) and the second kite section (41) is separated so that the kite (14) adopts a different aerodynamic state and falls to the ground together with the control pod (25). The invention also relates to a kite system.

Description

Background

[0001] The present invention relates to a method for landing a kite system. The kite system comprises a kite and a control pod, and the kite is held on the control pod via a line system. In normal operation of the kite system, the control pod is held on a ground attachment point via a tether. The present invention also relates to a kite system.

[0002] The kite is oriented substantially at a right angle to the tether, and can be moved by appropriate adaptation of aerodynamic properties along a flight path, thereby applying a tensile force to the tether.

[0003] For the operation of such a kite, a safety mechanism is desirable that still allows control to be applied to the kite even when it is impossible to maintain normal operation. For example, an operating condition may occur in which the control system fails and the kite can no longer be actively controlled. If the kite applies a high tensile force to the tether in this condition, it may not be possible to pull the kite in depending on the situation. Furthermore, a situation in which it is not possible to pull the kite in may also occur due to a failure of the tether winch. If the tether tears, joining the break point with a catch device is known from European Patent Application Publication No. 3456630. Since the catch device requires a certain distance to be able to absorb high forces, a portion of the flight altitude that can be used in normal operation is lost.

[0004] The object of the present invention is to propose such a method and a kite system that can reliably and safely land the kite system even outside normal operation. From the above-described prior art, this object is achieved by the features of the independent claims. Preferred embodiments are provided in the dependent claims.

[0005] In the method according to the present invention, the sail surface of the kite extends across a first kite portion and a second kite portion. A connection existing in the sail surface between the first kite portion and the second kite portion is separated such that the kite assumes a different aerodynamic state and falls to the ground together with the control pod.

[0006] The present invention recognizes that separating the connecting portion located within the sail surface between the first and second kite sections provides a quick and reliable method for correcting the aerodynamic state of the kite so that tensile forces are reduced. After the connecting portion is separated, an aerodynamic state is achieved in which the lift exerted by the kite is no longer sufficient to keep the kite system airborne. The kite and the control pod attached to it fall to the ground, and the kite functions as an umbrella.

[0007] In particular, the kite can function as a deceleration umbrella in this state so that the tension energy of the rope decreases without the rope experiencing a sudden reduction in load when the rope load is high. A sudden reduction in load is undesirable because it may cause the tether to bounce off the pulley at the ground station. If the tether is prevented from bouncing, the tether can be pulled further even though the emergency landing system has been triggered. The method is preferably performed such that after the trigger the kite rotates around the axis of the tether so that the kite falls to the ground under a low load, but with the tether pulled.

[0008] The sail face refers to the area of ​​the kite over which air flows when the kite is moved along its flight path. The sail face may include an inner surface facing the control pod and an outer surface facing the opposite side of the control pod. The inner and outer surfaces may be spaced apart from each other and spread out in an airfoil shape. The connecting section may extend in the direction of the airfoil so that both the first and second kite sections form a complete airfoil before separation. The direction of the airfoil is designated as the longitudinal direction of the kite. Viewed laterally, the first kite section may be positioned next to the second kite section.

[0009] The attachment point is on the ground if the kite cannot be lifted off the ground by its tensile force. Ground attachment points can be permanently connected to the ground. For example, ground attachment points on ships, floating barges, or land-based mobile systems are also possible.

[0010] During normal operation of the system, a connecting section is formed within the sail between the first kite section and the second kite section. The connecting section can form a continuous transition between the first kite section and the second kite section. The connecting section may be designed so that the sail and / or airfoil are not interrupted in the region of the connecting section.

[0011] The method may be carried out such that, after separation, the first kite portion and the second kite portion are completely separated from each other such that no connecting portion exists in the sail surface between the first kite portion and the second kite portion. In another embodiment, the first kite portion and the second kite portion are partially separated from each other such that, even after separation, a connecting portion still exists in the sail surface between the first kite portion and the second kite portion.

[0012] The first and second kite sections can be the same size such that the separation occurs at the center of the kite. It is also possible for the kite to have two kite sections of different sizes such that the separation occurs off-center.

[0013] A kite may include three or more kite sections. In any case, two of the kite sections involved will spread out on the sail in the sense of the present invention. The kite sections may be arranged adjacent to each other laterally on the kite, such that in any case the central kite section is contained between two kite sections that are adjacent to each other laterally. The connecting section that is separated when performing the method according to the present invention may be formed between two adjacent kite sections in any case. Even relatively large kites can be reliably landed by separating them into three or more kite sections.

[0014] The separation of the kite portion can be triggered by a trigger element. Therefore, the kite system can be configured so that the trigger element is automatically triggered when it is not possible to maintain the normal operation of the kite system. The trigger element can be triggered after an exceptional event. An exceptional event that would result in the inability to maintain normal operation could be, for example, a break in the wire or tether of the wire system, or an excessive load acting on the wire or tether of the wire system. An exceptional event can also result from a situation determined by the control unit where one or more operating parameters of the kite system are outside the normal range.

[0015] In addition to, or as an alternative to, independent triggers, the trigger element may be provided with the possibility of being triggered by an external intervention. An intervention might occur, for example, when the operator notices that the kite system has entered an abnormal state. The intervention might consist, for example, of the operator making an input or activating a switch.

[0016] A trigger signal can be mechanically transmitted to a trigger element. For example, a trigger element may be mechanically coupled to a rope so that it is triggered when the rope breaks or becomes overloaded. A trigger signal can also be a control signal that is electronically communicated to the trigger element. In particular, the control signal can be communicated to the trigger element by cable or via a wireless connection.

[0017] A kite may have a predetermined separation point at which the connection between the first kite section and the second kite section is separated. A fixing device may be provided at the predetermined separation point so that the connection between the first kite section and the second kite section is maintained as long as the fixing device is active. The predetermined separation point may be designed so that the connection between the first kite section and the second kite section is separated by applying an aerodynamic force acting on the sail surface when the fixing device is no longer active.

[0018] A predetermined separation point may include a zipper, which connects a first kite section and a second kite section. The zipper may be held closed by a fastening device. By releasing the fastening device, a portion of the zipper can be loosened, and as a result, the zipper can be opened longitudinally. From the loosened portion, the zipper can continue to open in one direction or both directions. In one embodiment, the zipper is designed so that some teeth are missing or not engaged in the area where the fastening device is located.

[0019] In other modifications, the kite portion may be joined at predetermined separation points to a material less tear-resistant than the adjacent material on the sail, such that the material at predetermined separation points tears after the fastening device is removed. A joint that loosens longitudinally after the fastening device is removed is also possible. In another embodiment, a fuse ignited by a trigger element extends along a predetermined separation point. The kite material can be weakened by the fuse at the predetermined separation point so that the kite tears.

[0020] A predetermined separation point may be designed to separate after the anchoring device has been released under the influence of aerodynamic forces generated during the normal operation of the kite system.

[0021] Furthermore, in order to separate the connecting parts, the kite can be subjected to a higher aerodynamic force at a predetermined separation point than during normal operation of the kite system. This method can be performed so that the higher aerodynamic force directly causes separation at the predetermined separation point. Alternatively, separation at the predetermined separation point can be achieved by a combination of removing the fixing device and the higher aerodynamic force.

[0022] The line system between the control pod and the kite may comprise multiple lines through which tensile force is transmitted from the kite to the control pod. The line system may comprise a line designed as an active steering line, the free length of which can be adjusted between the control pod and the kite. The kite may be steered by activating the active steering line to move along a desired flight path. The line system may comprise a line designed as a fixed line, which holds parts of the kite at a fixed distance apart. The line system may comprise a line designed as a passive steering line, extending between a first attachment point and a second attachment point on the kite, and being reoriented between the attachment points by a pulley connected to the control pod. The distance between the control pod and the first attachment point and the distance between the control pod and the second attachment point can be changed using such a passive steering line, while the sum of the two distances remains constant. The fixed line may be positioned in the part of the kite that is centered with respect to the lateral direction. A steering line may be positioned in the peripheral portion of the kite. A passive steering line may be positioned laterally in a portion of the kite located between the central and peripheral portions.

[0023] The kite system may be configured such that a wire in a wire system is cut by a trigger element. To enable cutting triggered by the trigger element, the wire or a retaining element connected to the wire may be provided with, for example, a pyrocutter or a compressed air shackle. When no tensile force acts on the relevant part of the kite, that part separates from the control pod. Movement of the relevant kite may be used to detach the anchoring device. For example, an anchoring wire may extend from the control pod to the anchoring device via the relevant part of the kite so that movement in the kite applies a tensile force to the anchoring device. The wire cut by the triggering element may be an anchoring wire.

[0024] A kite may be designed such that a cavity enclosed by an outer skin is surrounded between the outer and inner surfaces of the kite. During normal operation of the kite system, there may be a rise in pressure higher than the ambient pressure, for example, 50 mbar to 1000 mbar, preferably 100 mbar to 500 mbar. This rise in pressure may be supplied by the airflow along the sail surface as the kite moves along its flight path. The kite may have an inlet opening located between the outer and inner surfaces of the kite. In particular, the inlet opening may be located at the end face of the kite facing the direction of travel.

[0025] By separating the connection between the first and second kite sections, an opening can be created in the kite's outer sheath to release the rising pressure present inside the kite. By releasing the rising pressure, the aerodynamic state of the kite can be modified so that the tensile force acting in the direction of the control pod is reduced.

[0026] Furthermore, the present invention relates to a kite system comprising a kite and a control pod. The kite is held on the control pod via a wire system. The sail of the kite extends into a first kite portion and a second kite portion. A connecting portion is formed in the sail between the first kite portion and the second kite portion. The kite system includes a trigger element for separating the connecting portion so that the kite takes on different aerodynamic states after the connecting portion has been separated and fallen to the ground together with the control pod.

[0027] The kite system may include a tether extending between a control pod and a ground mounting point. The mounting point may be a component of the kite system fixedly connected to the ground. The kite system may be an element of a device for generating electrical energy. The device may include a generator driven via a tether winch. The kite system may also be connected to a mounting point on a ship so that the kite system can generate power for the ship. The ship's mounting point is a ground mounting point in the sense of this invention.

[0028] The kite system can be further developed with additional features described in connection with the method according to the present invention. The method can be further developed with additional features described in connection with the kite system according to the present invention.

[0029] The present invention is described below by way of example with preferred embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] [Figure 1] It is a schematic diagram of the device according to the present invention. [Figure 2] It is a schematic diagram of the operating state of the device of Figure 1. [Figure 3] It is a diagram showing a kite system according to the present invention. [Figure 4] It is an enlarged view of details of the kite system of Figure 3. [Figure 5] It is another enlarged view of details of the kite system of Figure 3. [Figure 6] It is yet another enlarged view of details of the kite system of Figure 3. [Figure 7] It is a diagram showing one state of the kite system according to the present invention. [Figure 8] It is a diagram showing another state of the kite system according to the present invention. [Figure 9] It is a diagram showing still another state of the kite system according to the present invention. [Figure 10] It is a diagram showing still another state of the kite system according to the present invention. [Figure 11] It is a diagram showing an alternative embodiment of the device according to the present invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0031] According to Figure 1, the device according to the present invention for generating electrical energy comprises the kite system (23) according to the present invention connected to a tether winch (16) via a tether (15). The kite system (23) comprises a kite (14) connected to a control pod (25) via a line system (24).

[0032] A power drive device 17 is connected to the tether winch 16, which functions as a generator in a first operating state and as a motor in a second operating state. The power drive device is connected to the public power grid 19 via a powertrain 18, which includes an inverter and a transformer, so that the electrical energy generated by the power drive device 17 can be supplied to the power grid 19, or so that the power drive device 17 can be operated as a motor using electrical energy taken from the power grid 19. The device includes a control unit 20 designed to control the interaction of the device's components.

[0033] The control unit 20 is equipped with an antenna 22 so that it can exchange control signals with the control pod 25 via a wireless connection 22. In particular, control signals are sent from the control unit 20 to the control pod 25 to control the flight path of the kite 14. The length of the steering wire of the line system 24 is modified using the control signals, and as a result the flight direction of the kite 14 is affected.

[0034] In the exemplary embodiment shown in Figure 2, the kite 14 is guided in a figure-eight shape, essentially oriented perpendicular to the wind direction W. As the kite 14 follows its flight path, a tensile force is applied to the tether 15, thereby driving the power drive device 17 via the tether winch 16. The mechanical energy is converted into electrical energy and supplied to the public power grid 19 via the powertrain 18 by the power drive device 17, which acts as a generator in this operating state. It is also possible to store a portion of the generated energy in the energy storage unit of the powertrain 18 in the form of electricity. In this way, electrical energy can be generated until the length of the tether 15 is exhausted and the entire tether 15 is released from the tether winch 16. The tether 15 is then pulled in by the power drive device 17, which acts as a motor, before it becomes possible to generate electrical energy again.

[0035] The line system 24 of the kite system 23 according to the present invention, as shown in Figure 3, comprises an active steering line 26, a passive steering line 27, and a fixed line 28, each connected to a control pod 25 and branching from a knot point 29 to multiple ends connected to the kite 14. The fixed line 28 extends from an end fixedly connected to the control pod 25 to the central portion of the kite 14. The active steering line 26, whose length can be adjusted, extends from the control pod 25 to two peripheral portions of the kite 24. The passive steering line 27, which can be oriented by a pulley 30 in the control pod 25, is connected to the kite 14 between the fixed line 28 and the active steering line 26.

[0036] The direction of movement of the kite 14 can be controlled by adjusting the length of the active steering wire 26. When the active steering wire 26 is adjusted, the passive steering wire 27 moves simultaneously on the pulley 30, while the length of the passive steering wire 27 that goes from the kite 14 over the pulley 30 and back to the kite 14 remains unchanged.

[0037] The kite 14 forms an airfoil that extends longitudinally from the end face 31 visible in Figure 3 to the rear end not visible in Figure 3, across the outer surface 32 and inner surface 33. During normal operation of the kite system, a cavity in the increased pressure is formed inside the kite 14. The kite 14 includes an opening 34 formed in the end face 31, through which air can enter the interior, thereby increasing the increased pressure as the kite 14 moves.

[0038] A zipper 36 is formed on the outer skin 35 of the kite 14, extending from the end face 31 to the rear end of the kite 14 over the length of the airfoil, across both the outer surface 32 and the inner surface 33. The zipper 36 is closed during normal operation of the kite system. By opening the zipper 36, the kite 14 can be separated into a first kite section 40 and a second kite section 41. In the sense of the present invention, the zipper 36 connects the first kite section 40 and the second kite section 41, forming a predetermined separation point between the first kite section 40 and the second kite section 41.

[0039] As shown in Figure 5, the zipper 36 includes a portion from which several teeth have been removed and which is secured by a fixing device 37. The fixing device 37 extends over the zipper 36 and holds the zipper closed despite the absence of teeth. The fixing device 37 can be removed by pulling the trigger line 38, and as a result, the zipper 36 can be loosened longitudinally by a force acting laterally on the zipper 36. Figure 6 shows the state of the zipper 36 immediately after the fixing device 37 has been removed, in which state the zipper 36 begins to open. By continuing to pull laterally, the zipper 36 can be opened along its entire length, and as a result, the first kite portion 40 and the second kite portion 41 are separated from each other.

[0040] As shown in Figure 3, the trigger wire 38 extends from the control pod 25 to the fixing device 37 via an attachment point 39 formed on the kite 14. When the fixing wire 28 is disconnected, the trigger wire 38 is pulled, causing the central portion of the kite 14 to separate from the control pod 25, thereby releasing the fixing device 37. As a result, the zipper 36 opens vertically, separating the kite 14 into a first kite section 40 and a second kite section 41. The opening of the zipper 36 creates an opening in the outer skin 35 of the kite 14 through which the rising pressure can escape. In this state, the first kite section 40 and the second kite section 41 each function as an umbrella from which the control pod 25 falls to the ground.

[0041] As shown in Figure 4, the pyrocutter 42 is positioned adjacent to the control pod 25 of the fixed wire 28. The pyrocutter 42 can be triggered by an electrical signal, resulting in the disconnection of the fixed wire 28. The pyrocutter 42 forms a trigger element in the sense of the present invention. An electrical signal for triggering the pyrocutter 42 may be provided and generated by the control unit 20 when an exceptional event occurs, thereby preventing the kite system from operating under normal conditions.

[0042] After the anchoring wire 28 is cut, the central portion of the kite 14 rises and thus separates from the control pod 25, resulting in tensile stress being applied to the trigger wire 38. The anchoring device 37 is removed and the zipper 36 is opened so that the control pod, along with the two kite portions 40 and 41 that act as an umbrella, falls to the ground.

[0043] The relevant sequences are shown in Figures 7 to 10. The kite system 23 is shown in Figure 7 in normal operation. In Figure 8, the fixing line 28 is cut so that the central portion of the kite 14 rises and the fixing device 37 separates from the zipper 36. In Figure 9, the zipper 36 is partially loosened. After the zipper 36 is completely loosened, the two kite sections 40 and 41 separate from each other. As the rising pressure escapes from the inside, the kite sections 40 and 41 lose their aerodynamic profile and continue to function only as umbrellas.

[0044] An alternative embodiment of the present invention is shown in Figure 11, in which the kite system 23 according to the present invention is used to generate power for a ship 43.

Claims

1. A method for landing a kite system (23), wherein the kite system (23) comprises a kite (14) and a control pod (25), the kite (14) being held on the control pod (25) via a line system (24), the control pod (25) being held on a ground attachment point (16, 44) via a tether (15) during normal operation of the kite system (23), the sail of the kite (14) being spread into a first kite portion (40) and a second kite portion (41), and a connecting portion (36) existing in the sail between the first kite portion (40) and the second kite portion (41) being separated so that the kite (14) takes on different aerodynamic states and falls to the ground together with the control pod (25).

2. The method according to claim 1, characterized in that the sail surface includes an inner surface (33) facing the control pod and an outer surface (32) facing the opposite side of the control pod, and the inner surface (33) and the outer surface (32) are spaced apart from each other and spread out in an airfoil shape.

3. The method according to claim 1 or 2, characterized in that, after separation, the first kite portion (40) and the second kite portion (41) are completely separated from each other such that there are no longer any connecting portions within the sail surface between the first kite portion (40) and the second kite portion (41).

4. The method according to claim 1, characterized in that the separation of the connecting portion (36) is triggered by a trigger element (42).

5. The method according to claim 4, characterized in that the trigger element (42) is triggered by a control signal from the control unit (20).

6. The method according to claim 1, characterized in that the kite (14) has a predetermined separation point (36) that forms the connecting portion between the first kite portion (40) and the second kite portion (41).

7. The method according to claim 6, characterized in that the predetermined separation point includes a zipper (36), and the zipper (36) connects the first kite portion (40) and the second kite portion (41) to each other during normal operation of the kite system (23).

8. The method according to claim 7, characterized in that the predetermined separation point (36) is fixed by a fixing device (37) during the normal operation of the kite system (23).

9. The method according to claim 8, characterized in that the zipper (36) is designed such that some teeth are missing or do not engage in the area where the fixing device (37) is placed.

10. The method according to claim 4, characterized in that, after the triggering of the trigger element (42), the kite (14) is in an aerodynamic state in which the force acting on the connecting portion (36) is higher than during the normal operation of the kite system (23).

11. The method according to claim 4, characterized in that the lines (26, 27, 28) of the line system (24) are cut by the trigger of the trigger element (42).

12. The method according to claim 1, characterized in that by separating the connecting portion (36) between the first kite portion (40) and the second kite portion (41), an opening can be created in the outer skin (35) of the kite (14) to release the increased pressure present inside the kite (14).

13. A kite system (23) comprising a kite (14) and a control pod (25), wherein the kite (14) is held on the control pod (25) via a line system (24), the sail surface of the kite (14) extends into a first kite portion (40) and a second kite portion (41), a connecting portion (36) between the first kite portion (40) and the second kite portion (41) is formed in the sail surface, and the kite system (23) further comprises a trigger element (42) for separating the connecting portion (36) such that, after separation, the kite (14) takes on a different aerodynamic state and falls to the ground together with the control pod (25).

14. The kite system according to claim 13, characterized in that the control pod (25) is held on a ground mounting point (16, 44) via a tether (15) during normal operation of the kite system (23).

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