Hatch arrangement for closing an opening in a floor of a wind turbine and a wind turbine

Abstract

A hatch arrangement with at least one slidable hatch for closing an opening in a floor of a wind turbine including a first guiding device fixedly mountable to the floor and a second guiding device pivotably mountable to the floor, a first coupling means to guide the slidable hatch along a first guidance path in the first guiding device and a second coupling means to couple the slidable hatch at least pivotably to the second guiding device, wherein the slidable hatch is coupled to the first guiding device at a first position and to the second guiding device at a second position, wherein a movement of the slidable hatch from a closed position along the first guidance path results in a pivoting movement of the second guiding device and in a movement of the slidable hatch to an open position and vice versa is provided.

Claims

1. A hatch arrangement with at least one slidable hatch for closing an opening in a floor of a wind turbine, the hatch arrangement comprising: a first guiding device which is fixedly mountable to the floor; a second guiding device which is pivotably mountable to the floor; a first coupling means to guide the at least one slidable hatch along a first guidance path in the first guiding device and a second coupling means to couple the at least one slidable hatch at least pivotably to the second guiding device; and a hinged hatch which is pivotably mountable to the floor, wherein the hinged hatch can be brought from a closed position into an open position and vice versa by pivoting the hinged hatch around a pivot axis of the hinged hatch, further wherein the at least one slidable hatch and the hinged hatch are, if both in the open position, located on opposite sides of the opening; wherein the at least one slidable hatch is coupled to the first guiding device at a first position and to the second guiding device at a second position, the first position and the second position being located along a longitudinal direction of the at least one slidable hatch and spaced apart from each other; wherein a movement of the at least one slidable hatch from a closed position along the first guidance path results in a pivoting movement of the second guiding device and in a movement of the at least one slidable hatch to an open position and vice versa.

2. The hatch arrangement according to claim 1, wherein the second guiding device comprises a second guidance path, and the second coupling means is further adapted to guide the at least one slidable hatch along the second guidance path at the second position.

3. The hatch arrangement according to claim 2, wherein the first guidance path comprises a first section and a second section, and a movement of the at least one slidable hatch along the first section from the closed position results in a transmission of force from the at least one slidable hatch to the second guiding device using the second coupling means which is located at an end stop of the second guidance path, further wherein the force causes the second guiding device to pivot from a first orientation into a second orientation, further wherein the hatch arrangement comprises a stopper which defines the second orientation as the position where the stopper blocks the second guiding device with respect to the pivoting movement, further wherein the movement of the at least one slidable hatch along the second section results in a movement of the second coupling means along the second guidance path while the second guiding device remains in the second orientation.

4. The hatch arrangement according to claim 2, wherein the second guiding device comprises two second guiding rails which are pivotably mountable on the floor such that the second guiding rails are pivotable around a horizontal pivot axis, which is perpendicular to the first guidance path, further wherein the second coupling means comprises two second sliders arranged on two opposite sides of the slidable hatch, wherein each second slider is movable along one of the second guiding rails.

5. The hatch arrangement according to claim 1, wherein the first guiding device comprises two hollow first guiding rails which are fixedly mountable parallel to each other laterally on two opposite sides of the opening, further wherein the first coupling means comprises two first sliders which are arranged on two adjacent corners of the slidable hatch, and each first slider is movable along one of the first guiding rails.

6. The hatch arrangement according to claim 1, wherein, if the at least one slidable hatch and the hinged hatch are both in the closed position, the at least one slidable hatch is arranged below the hinged hatch.

7. The hatch arrangement according to claim 1, wherein the at least one slidable hatch comprises a hatch opening for a wire in the closed position.

8. The hatch arrangement according to claim 1, further comprising at least one elastic means in or at the first guiding device and/or the second guiding device, wherein closing the at least one slidable hatch leads to an elastic deformation of the at least one elastic means against an elastic force of the at least one elastic means.

9. The hatch arrangement according to claim 1, further comprising a holding means configured to hold the at least one slidable hatch in the open position.

10. A wind turbine comprising at least one hatch arrangement according to claim 1.

11. The wind turbine according to claim 10, wherein the opening is arranged on a floor of a nacelle and/or on a platform within a tower of the wind turbine.

12. The wind turbine according to claim 10, wherein the at least one slidable hatch and the hinged hatch are located on two opposite sides of the opening, further wherein on each of the two other opposing sides a component of the wind turbine is located, wherein each of the components prevents a user from falling into the opening from the respective side.

13. A hatch arrangement with at least one slidable hatch for closing an opening in a floor of a wind turbine, the hatch arrangement comprising: a first guiding device which is fixedly mountable to the floor; a second guiding device which is pivotably mountable to the floor; and a first coupling means to guide the at least one slidable hatch along a first guidance path in the first guiding device and a second coupling means to couple the at least one slidable hatch at least pivotably to the second guiding device; wherein the at least one slidable hatch is coupled to the first guiding device at a first position and to the second guiding device at a second position, the first position and the second position being located along a longitudinal direction of the at least one slidable hatch and spaced apart from each other; wherein a movement of the at least one slidable hatch from a closed position along the first guidance path results in a pivoting movement of the second guiding device and in a movement of the at least one slidable hatch to an open position and vice versa; wherein the at least one slidable hatch comprises a hatch opening for a wire in the closed position.

14. A hatch arrangement with at least one slidable hatch for closing an opening in a floor of a wind turbine, the hatch arrangement comprising: a first guiding device which is fixedly mountable to the floor; a second guiding device which is pivotably mountable to the floor; and a first coupling means to guide the at least one slidable hatch along a first guidance path in the first guiding device and a second coupling means to couple the at least one slidable hatch at least pivotably to the second guiding device; wherein the at least one slidable hatch is coupled to the first guiding device at a first position and to the second guiding device at a second position, the first position and the second position being located along a longitudinal direction of the at least one slidable hatch and spaced apart from each other; wherein a movement of the at least one slidable hatch from a closed position along the first guidance path results in a pivoting movement of the second guiding device and in a movement of the at least one slidable hatch to an open position and vice versa; wherein the first guiding device comprises two hollow first guiding rails which are fixedly mountable parallel to each other laterally on two opposite sides of the opening, further wherein the first coupling means comprises two first sliders which are arranged on two adjacent corners of the slidable hatch, and each first slider is movable along one of the first guiding rails.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 depicts an embodiment of a wind turbine comprising several hatch arrangements;

(3) FIG. 2 depicts a first part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(4) FIG. 3 depicts a second part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(5) FIG. 4 depicts a third part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(6) FIG. 5 depicts a fourth part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(7) FIG. 6 depicts a fifth part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(8) FIG. 7 depicts a sixth part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(9) FIG. 8 depicts a seventh part of the process of opening one of the hatch arrangements of the wind turbine according to FIG. 1 in a side view;

(10) FIG. 9 depicts the first part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(11) FIG. 10 depicts the second part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(12) FIG. 11 depicts the third part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(13) FIG. 12 depicts the fourth part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(14) FIG. 13 depicts the fifth part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(15) FIG. 14 depicts the sixth part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(16) FIG. 15 depicts the seventh part of the opening process of the hatch arrangement according to FIGS. 2 to 8 in a perspective side view;

(17) FIG. 16 depicts a vertical cut through a first guiding device of the hatch arrangement according to the previous figures;

(18) FIG. 17 depicts a vertical cut through a second guiding device of the hatch arrangement according to the previous figures;

(19) FIG. 18 depicts a detailed view of a slidable hatch of the hatch arrangement according the previous figures; and

(20) FIG. 19 depicts a sectional view along the line XIX-XIX in FIG. 18.

DETAILED DESCRIPTION

(21) FIG. 1 shows a longitudinal cut through a wind turbine 1 according to the present invention. The wind turbine 1 comprises a tower 2 and a nacelle 3 which is located on top of the tower 2 and houses components of the wind turbine 1, like an electric generator and others. The wind turbine 1 further comprises several floors 4, namely several working platforms 5 within the tower 2 and a nacelle floor 6. Each of the floors 4 comprises an opening 7. The openings 7 are provided to crane loads 8, e.g. from one of the floors 4 to another, or from or to a base 9 of the wind turbine 1. Optionally, the openings 7 can be parts of an access path of the wind turbine 1, e.g. from the base 9 via the working platforms 5 to the nacelle 3.

(22) To crane, i.e. to hoist or to lower, the load 8 through the respective opening 7, a crane 10 is provided which is exemplarily located in the nacelle 3. The crane 10 comprises a wire 11 with a hook 12 to hoist/lower the load 8. Since the openings 7 are located above each other along a vertical line and the crane 10 is located above the openings 7, the crane 10 can be used as a common means to crane loads between the base 9, the working platforms 5 and the nacelle 3. However, several cranes on several platforms 5 or the nacelle 3, respectively, can be provided.

(23) The wind turbine 1 comprises several hatch arrangements 13 according to the present invention, wherein the hatch arrangements 13 are adapted to open and close the respective opening 7. While not in use, e.g. while no load 8 is desired to be craned through one of the openings 7, the respective hatch arrangement 13 is closed to prevent persons or objects from falling down through the openings 7 unintentionally. However, if the load 8 is supposed to be craned through the opening 7, the respective hatch arrangement 13 can be brought into an open state. In FIG. 1, the hatch arrangement 13 of the nacelle floor 6 and the hatch arrangements 13 of the uppermost working platform 5 are in a closed state. As will be described later in more detail, the wire 11 is, nonetheless, going through these hatch arrangements 13. The hatch arrangement 13 of the lowermost working platform 5 is in the open state, since the load 8 is desired to be hoisted through the respective opening 7.

(24) Next, bringing the hatch arrangement 13 from the closed state into the open state, that is opening the hatch arrangement 13, and the mechanical system will be explained in more detail with the help of FIGS. 2 to 8. FIGS. 9 to 15 show the same opening process of the hatch arrangement 13 from another, perspective point of view. FIG. 9 shows the same situation as FIG. 2, FIG. 10 shows the same situation as FIG. 3 and so on.

(25) The hatch arrangement 13 comprises a slidable hatch 14 and a hinged hatch 15. The hatch arrangement 13 is in the closed state if at least one of the hatches 14, 15 is in a closed position, in particular if both hatches 14, 15 are in the closed position. The hatch arrangement 13 is in the open state if both hatches 14, 15 are in an open position. According to the closed state of the hatch arrangement 13, the slidable hatch 14 is arranged below the hinged hatch 15.

(26) Starting from the hatch arrangement 13 being in the closed state as shown in FIG. 2, a user 16 can open the hinged hatch 15, which is pivotably mounted on the floor 4. To bring the hinged hatch 15 from the closed, namely horizontal or lying, into the open, namely vertical or standing, position and vice versa, the hinged hatch 15 can be pivoted around a pivot axis 17. Since the slidable hatch 14 is in the closed, namely horizontal or lying, position while the hinged hatch 15 is opened by the user 16, the user 16 can step onto the slidable hatch 14 while pivoting the hinged hatch 15 into the open position. After the hinged hatch 15 has been brought into the open position (see FIG. 3) the user 16 can open the slidable hatch 14 to finally bring the hatch arrangement 13 into the open state while the opened hinged hatch 15 provides a security barrier on the other side of the opening 7.

(27) Next, the mechanical components of the hatch arrangement 13 will be described in more detail. The hatch arrangement 13 comprises a first guiding device 18 with exemplarily two hollow first guiding rails 19 which are fixedly mounted parallel to each other on the floor 4 laterally on two opposite sides of the opening 7. The hatch arrangement 13 furthermore comprises a first coupling means 20 to guide the slidable hatch 14 along a first guidance path 21 of the first guiding device 18. The first coupling means 20 exemplarily comprises two first sliders 22 which are arranged on two adjacent corners of the slidable hatch 14, wherein each first slider 22 is movable along one of the first guiding rails 19 and the first guidance path 21, respectively. The first sliders 22 are located in one of the first guiding rails 19 each at a first position 23, wherein the first position 23 is located on a longitudinal axis or direction of the slidable hatch 14. Hence, two first guidance paths 21 are provided, wherein each of the guidance paths 21 is provided for one of the guiding rails 19.

(28) The hatch arrangement 13 furthermore comprises a second guiding device 24, which is pivotably mounted to the floor 4, namely around a pivot axis 25, which is, regarding the opening 7, located on the opposite side of the pivot axis 17 of the hinged hatch 15. The pivot axes 17, 25 are parallel to each other and, hence, perpendicular to the first guidance path 21. The second guiding device 24 comprises exemplarily two second guiding rails 26, which are pivotably mounted on the floor 4 such that the second guiding rails 26 are pivotable around the horizontal pivot axis 25.

(29) The hatch arrangement 13 comprises a second coupling means 27 to couple the slidable hatch 14 with the second guiding device 24. The second coupling means 27 comprises exemplarily two second sliders 30 which are arranged on two opposite sides of the slidable hatch 14, wherein each second slider 30 is movable along one of the second guiding rails 26. The second coupling means 27 couples the slidable hatch 14 pivotably to the second guiding device 24 and guides the slidable hatch 14 along the second guidance path 28 of the second guiding device 24 at a second position 29. Hence, each of the second sliders 30 is movable along the second guidance path 28 of the respective second guiding rail 26.

(30) The positions 23, 29 are located along the longitudinal axis of the slidable hatch 14, wherein the first and the second position 23, 29 are spaced apart from each other.

(31) Next, the first sliders 22 are described in more detail. Each of the first sliders 22 is located within the respective first guiding rail 19, which comprises a U-shaped cross section, wherein each of the two end sections of the U-shaped cross section comprises a lateral protrusion, wherein the two protrusions are facing towards each other to hold the first slider 22 within the first guiding rail 19. The first sliders 22 are rectangular and block-like components which comprise, concerning their surface which faces the opening of the U-shaped cross section of the first guiding rails 19, a bore hole or a bolt to interact with a respective bolt or bore hole of the slidable hatch 14 such that the sliders 22 allow the movement of the slidable hatch 14 along the guiding rails 19 and a pivot motion of the slidable hatch 14 with respect to the first guiding device 18. The position of the first sliders 22 along the first guidance path 21 defines the current coupling location of the first position 23.

(32) Next, the second sliders 30 are described in more detail. Each of the second sliders 30 comprises a protrusion which engages into an undercut longitudinal groove of the respective second guiding device 24. Alternatively, the second slider 30 may comprise protrusions which surround the respective bar- or rod-like second guiding rail 26. The second coupling means 27 furthermore comprises a holding component which is attached to the slidable hatch 14, wherein the holding component is pivotably coupled to the respective slider 30. Hence, using the sliders 30, the slidable hatch 14 can be moved along the second guidance path 28 of the second guiding device 24. Furthermore, the pivotably held sliders 30 allow for the pivot motion of the slidable hatch 14 with respect to the second guiding device 24. The position of the second sliders 30 along the second guidance path 28 defines the current location of the second position 29 with respect to the second guidance path 28.

(33) Next, bringing the slidable hatch 14 from the closed, namely horizontal or lying, position (see FIG. 3) into the open, namely vertical or standing, position (see FIG. 8) will be described in more detail. This can be performed by the user 16 by pulling the slidable hatch 14 into the open position. The first guidance path 21 is divided into two subsequent sections, namely a first section 31 and a second section 32. As can be seen in FIGS. 3 to 6, the movement of the slidable hatch 14 from the closed position along the first section 31 of the first guidance path 21 mainly results in a pivoting movement of the second guiding device 24. As can be seen in FIGS. 6 to 8, the subsequent movement of the slidable hatch 14 along the second section 32 of the first guidance path 21 mainly results in a pivoting movement of the slidable hatch 14 into the open position.

(34) Next, the movement of the slidable hatch 14 along the sections 31, 32 will be described in more detail. Starting from the closed position, the movement of the slidable hatch 14 and, hence, of the first sliders 22 along the first section 31 results in a transmission of force from the slidable hatch 14 to the second guiding device 24. While the hinged hatch 14 moves along the first section 31, the second coupling means 27 is located at an end stop 33 of the second guidance path 28. The end stop 33 is the end of the second guidance path 28 which faces the pivot axis 25. Since the angle between the force and the free direction of the second guidance path 28 is, in particular in the situations as shown in FIGS. 3 to 5, larger than 90°, the second sliders 30 are pressed against the end stop 33 which causes the second device 24 to pivot from a first, namely horizontal or lying, orientation (FIG. 3) into a second, namely vertical or standing, orientation (FIGS. 6 to 8), while the second position 29 or second slider 30, respectively, remains at the end stop 33. Even if the angle between the force and the free direction of the second guiding path 28 becomes smaller than 90°, the gravitational force of the hinged hatch 14 is large enough to keep the second position 29 at the end stop 33.

(35) During the movement of the slidable hatch 14 along the first section 31, the slidable hatch 14 moves towards the user 16 who, as a consequence, has to step back while opening the slidable hatch 14. This increases the distance between the user 16 and the opening 7, reducing the risk of the user 16 falling down into the opening 7.

(36) The hatch arrangement 13 comprises a stopper 34 which defines the second orientation of the second guiding device 24. At the second orientation, the stopper 34 blocks the second guiding device 24 with respect to its pivoting movement. In other words, the stopper 34 defines the end of the first section 31 and the beginning of the second section 32. Once the second guiding device 24 has reached the second orientation (see FIG. 6), the subsequent movement of the slidable hatch 14 along the second section 32 of the first guidance path 21 begins. This movement results in a movement of the second coupling means 27 along the second guidance path 28. During this movement, the second guiding device 24 remains in the second orientation, which is shown in FIGS. 6 to 8. During the movement of the slidable hatch 14 along the second section 32 of the first guidance path 21, the slidable hatch 14 mainly pivots into the vertical position. Hence, the slidable hatch 14 acts as a safety barrier, opposing the barrier formed by the open hinged hatch 15, preventing the user 16 from falling down through the opening.

(37) However, as can be seen from FIGS. 3 and 4, large loads 8 can already be placed above the opening 7 while the slidable hatch 14 is still in the closed position. As can be seen from FIGS. 4 to 6, while using the first section 31 of the first guidance path 21, the slidable hatch 14 slides away under the load 8, not gaining much height and providing a large available space for loads, since most of the pivoting of the slidable hatch 14 into the open position takes place at the side of the opening 7 while using the second section 32 and the second guidance path 28.

(38) Although only the opening process of the hatches 14, 15 has been described on the basis of FIGS. 2 to 15, the closing processes can be performed analogously.

(39) Now referring to FIG. 8, where the hatch arrangement 13 is in the open state, on two opposite sides of the opening 7 the slidable hatch 14 and the hinged hatch 15, which are in the open position each, are located. Regarding these two sides, the hatches 14, 15 act as a prevention means to prevent people or objects from falling down through the opening 7 from the respective sides or direction. On each of the two other opposing sides, a component 35 of the wind turbine 1 is located, wherein each of the components 35 prevent persons or objects from falling into the opening 7 from the respective side. Note that in FIGS. 2 to 15 only one of the components 35 is shown. The components 35 are exemplarily electric cubicles 36 of the wind turbine 1. From the view of the user 16, his side is secured by the slidable hatch 14 and the other three sides are secured by the electrical cubicles 36 and the hinged hatch 15. Hence, the components 35 and the hatches 14, 15 replace guiding rails, which typically have to be mounted at the opening 7 to prevent objects or people from falling down.

(40) To avoid remaining open gaps between the components 35 of the wind turbine 1 and the hinged hatch 15 being in the open position, the hinged hatch 15 exemplarily comprises two lateral side walls 49 to close these gaps. To close these gaps completely, the side walls 49 have a width of exemplarily 20 centimetres. In the closed position of the hinged hatch 15, the side walls 49 laterally cover the other components of the hatch arrangement, in particular the slidable hatch 14 and the guiding devices 18, 24.

(41) Another advantage of the hatch arrangement 13 concerns the load 8. After the hinged hatch 15 has been opened, the load 8 can be brought over the opening 7 using the crane 10. As can be seen in FIGS. 4 to 8, the movement of the slidable hatch 14 allows the load 8 to be positioned closely above the opening 7. If, like in many traditional systems, only the hinged hatch 15 would be provided, there would not be enough space to locate the load 8 that close upon the opening 7 before opening the hinged hatch 15. In these systems, the load 8 has to be hoisted over the hinged hatch 15 in the open state or over the respective guiding rails, which have to be mounted before opening the hinged hatch 15. Hence, the crane 10 has to be much higher or larger than in the present invention. In the shown embodiment of the present invention, this concerns in particular the nacelle 3 of the wind turbine 1, where the crane 10 is located. Basically, further cranes can be provided on other floors 4 than the nacelle floor 6.

(42) Another aspect of the hatch arrangement 13 is explained in FIGS. 16 and 17. As can be seen in FIG. 16, the hatch arrangement 13 or the first guiding device 18, respectively, comprises a holding means 37, wherein the holding means 37 is adapted to hold the slidable hatch 14 in the open position. The holding means 37 is a U-shaped lateral recess 38 of the first guidance path 21. Once the slidable hatch 14 is in the open position, the first coupling means latches into the lateral recess 38. To close the slidable hatch 14 again, the user 16 has to lift the slidable hatch 14 a bit and push against the slidable hatch 14 with his foot. Alternatively, the holding means 37 can be a clamping means.

(43) A further holding means, although not shown in the figures, is exemplarily provided for the hinged hatch 15. The further holding means is a clamping means to releasably clamp a pivot joint of the hinged hatch 15 at the pivot axis 17. Additionally or alternatively, the hinged hatch 15 can be held by its own gravity in the open position, which is, e.g., realised by an angle between the hinged hatch 15 and the floor 4 of larger than 90°, e.g. of 100°, if the hinged hatch 15 is in the open position.

(44) FIG. 16 shows another aspect concerning the first guiding device 18. The hatch arrangement 13 comprises an elastic means 39 with a first spring 40 which is arranged at or in the first guiding rail 19. While closing the slidable hatch 14, the first spring 40 deforms elastically against the elastic force of the first spring 40. One end side of the first spring 40 is located at the first coupling means 20 and the other end side is located at the end stop of the first guiding rail 19 which is opposed to the holding means 37.

(45) The elastic means 39, as depicted in FIG. 17, comprises a second spring 41, which is located at the second guiding device 24. One end side of the second spring 41 is located at the second coupling means 27 and the other end side is located, regarding the second orientation of the second guiding device 24, at the lower end of the second guidance path 28. Closing the slidable hatch 14, hence, leads to an elastic deformation of the second spring 41 against the elastic force of the second spring 41.

(46) As a consequence, when closing the slidable hatch 14, a certain portion of the potential energy of the slidable hatch 14 and of the second guiding device 24 is stored in the first spring 40 and the second spring 41. As a consequence, the movement of the slidable hatch 14 while closing it is softer compared to the case when no elastic means 39 is provided. Furthermore, the energy stored in the elastic means 39 supports the user 16 when opening the hinged hatch 14 by pulling it on its, regarding the open position, upper side 42 which is opposed to the lower side 43.

(47) The properties of the elastic means 39, in particular the spring stiffness of the springs 40, 41 are chosen such that after initiating the closing of the slidable hatch 14, the slidable hatch 14 automatically changes from the open into the closed position.

(48) Although not shown in the figures, the hinged hatch 15 of the hatch arrangement 13 comprises a further elastic means, wherein closing the hinged hatch 15 leads to an elastic deformation of the further elastic means against the elastic force of the further elastic means. The further elastic means is exemplarily a leg spring which is located at the pivot axis 17 of the hinged hatch 15.

(49) Alternatively, a, in particular electrical and/or hydraulic, driving means can be provided to bring the slidable hatch 14 and/or the hinged hatch 15 from the closed position into the open position and vice versa.

(50) Another aspect of the hinged hatch 14 is shown in FIGS. 18 and 19, wherein FIG. 19 shows a sectional view through the slidable hatch 14 along the line XIX-XIX in FIG. 18. The slidable hatch 14 comprises a hatch opening 44 on the lower side 43. The opening 43 allows the wire 11 to go through the slidable hatch 14 in the closed position. The hatch opening 44 is a lateral slit 45 allowing the hinged hatch 14 to be opened and closed while the wire 11 passes through the hatch opening 44. The lateral slit 45 can be cut into a cover blade 46 of the slidable hatch 14 which particularly consists of steel or grated steel. The slidable hatch 14 comprises a preserving means 47, which consists of a, in particular replaceable, soft material like a rubber or another synthetic material such as a plastic material. The preserving means 47 avoids the wire 11 from scratching directly against the metal of the cover plate 46 during operation. The lateral slit 45 can have a width, regarding the preserving means 47, of 30 mm and, regarding the cover plate 46, of 50 mm. The cover plate 46 can have a thickness of 4 mm. The lateral slit 45 of the preserving means 47 can comprise an oblique tread 48 for an easy insertion of the wire 11 into the lateral slit 45 while closing the slidable hatch 14.

(51) Although not explicitly shown in the figures, the hinged hatch 15 also comprises a hatch opening, namely a lateral slit on its, regarding the open position, upper side, and a preserving means. The hatch opening and the preserving means of the hinged hatch 15 act analogously to the hatch opening 44 and the preserving means 47 of the slidable hatch 14.

(52) The hatch opening 44 of the slidable hatch 14 and the hatch opening of the hinged hatch 15 allows the wire 11 to go through the respective hatch 14, 15, even if the hatches 14, 15 are in the closed position, like it is shown for the uppermost two hatch arrangements 13 in FIG. 1.

(53) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(54) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.