TECHNICAL FIELD

The invention relates to a top-hinged foldable concertina door for a marine vessel, comprising a top door panel, at least one mid-door panel and a bottom door panel arranged to seal a coaming in either the superstructure or in the hull of the marine vessel. The concertina door is especially suited for use as a helicopter hangar door on a naval vessel.

BACKGROUND

Doors for marine vessels are built to withstand harsh weather conditions in all conceivable sea states. In closed position the door must withstand sea spray, green sea, wind pressure, icing and ship dynamic motions. In the particular case of a helicopter hangar door at the flight deck of a naval vessel, the door must also withstand added temporary load from vertical and reflected horizontal wind force from a helicopter at landing and take-off. Furthermore, the door must function at maximal longitudinal and transversal inclination depending on current sea state and ship speed according to rigid naval building specifications.

Several types of hangar doors are well known in the art, including roller gate doors and concertina doors of various kinds. Roller gates are generally thin, compact and unobtrusive but tend to be weaker than folding concertina doors. Known types of concertina doors on the other hand, are generally more robust, but they require much space for stowage either inside or outside of the hangar - a feature that is often undesirable in a cramped environment of a helicopter hangar on a naval vessel. SUMMARY

An object of the invention is to alleviate the above mentioned problems by providing a top-hinged foldable concertina door for a marine vessel, comprising a top door panel, at least one mid-door panel and a bottom door panel arranged to seal a coaming in either the superstructure or in the hull of the marine vessel. The top panel is hinged in a top portion of the coaming and hinged to the mid-door panel which in turn is hinged to the bottom door panel and said door being provided with a compressible sealing gasket arranged to seal against the coaming when the door is closed. The invention is especially characterized in:

- that the door and the coaming have slanting sides forming a wedge-shaped door opening with a downwardly narrowing width;

- that the door, in an initial opening stage, is arranged to be raised linearly relative to the coaming with the door panels maintained in a common plane for a linear raising distance allowing the sealing gasket to uncompress and disengage from the slanting sides of the coaming, and

- that the door panels are arranged to be folded in a secondary opening stage into a stowed, fully folded position at the top portion of the coaming. In a favourable embodiment of the invention the slanting angle of the slanting sides are between 2 and 10 degrees, preferably between 4 and 6 degrees.

Favourably, the top door panel is arranged to be pivoted at its top edge whereas the other door panels are arranged to be pivoted at half their height. In a preferred embodiment, the top door panel is arranged to be pivoted inwards towards the inside of the coaming.

The top door panel may favourably be provided with a winch adapted to hoist and lower the folding door panels by means of a system of wires and pulleys.

In an advantageous embodiment of the invention, the height of the top door panel is half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with equal protrusion lengths inside and outside of the coaming.

In an alternative embodiment of the invention, the height of the top door panel is more than half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with an external protrusion length being less than its internal protrusion length relative to the coaming.

In another alternative embodiment of the invention, the height of the top door panel is less than half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with an external protrusion length exceeding its internal protrusion length relative to the coaming.

The bottom door panel is provided with a lower guide pin protruding horizontally outwards from each side. The guide pins are arranged in a lower half section of the bottom door panel and are each adapted to slide within a lower side guiding console having a first linear guide section oriented in the plane of the door opening and directed perpendicularly upwards with respect to a horizontal bottom edge of the coaming. The guiding console also has a second, angled guide section arranged at an angle to said first linear guide section. The first linear guide section is arranged to guide the door linearly upwards in the initial opening stage, whereas angled guide section initiates the folding movement of the door panels.

The door is prevented from folding in its closed lowered position by means of an auto-cleat system including upwardly open, U-shaped cleats positioned on each side of the coaming. The cleats are positioned at heights corresponding to a horizontal hinge axis between the top door panel and the mid-door panel as well as a horizontal hinge axis between the mid-door panel and the bottom door panel. These cleats are adapted to receive locking pins protruding from the slanting sides at said hinge axes. The locking pins are held within the cleats in said closed lowered position of the door and during the initial linear opening stage of the door. The invention provides certain advantages over previously known technology, primarily due to the fact that this door can protrude from the coaming - in stowed position - both inward and outwards throug h the coaming and therefore enable use the "dead volume" that wou ld otherwise are u nusable with known types of concertina doors. The concertina door of the invention is especially su itable for naval vessels with a reduced radar cross-section desig n .

The concertina door of the invention may also advantageously be used as a mission bay door on the sides or at the stern of a marine vessel.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

Fig. 1 shows a cut-out perspective view of a top-hinged foldable concertina door according to the present invention. The door is shown in its closed position. Fig. 2 shows a broken side view of a naval vessel with a flight deck, a helicopter and a helicopter hangar having a concertina door according to the invention. This view is an example of use of the invention, although the door may also be used in other positions on the marine vessel.

Fig. 3 shows a simplified and geometrically exaggerated schematic view of a concertina door as seen from inside a helicopter hangar. The door is shown in a closed position and also in a partially open position indicated by dashed lines. shows a cut-out cross-sectional view taken along line IV-IV in Fig. 3 of a door panel and the coaming with the door in its closed position in which the sealing gasket is compressed against the coaming. shows a similar cross-sectional view as in Fig. 4, only here the door is shown directly after its initial opening stage where the door has parted from the sides of the coaming and the sealing gasket is uncompressed. shows a side view of the concertina door in a closed position. shows a side view of the concertina door in a position where the door panels have just begun to fold after the initial linear opening stage. shows a broken, enlarged side view of the top door panel and its upper guiding console with the concertina door in a position where the door panels have just begun to fold. shows a broken, enlarged side view of the top door panel and its upper guiding console with the concertina door in a closed position. is a perspective view of the concertina door in its closed position as viewed from the inside of the helicopter hangar. is a perspective view of the concertina door in a position where the door panels have just begun to fold after the initial linear opening stage as viewed from the inside of the helicopter hangar. shows a side view of the concertina door in a position where the door panels are folded 45 degrees. shows a side view of the concertina door in a fully opened, stowed position at the top portion of the coaming. is a perspective view of the concertina door in a position corresponding to Fig. 12 where the door panels are folded 45 degrees as viewed from the inside of the helicopter hangar. is a perspective view of the concertina door in a position corresponding to Fig. 12 and 14 where the door panels are folded 45 degrees, but here as viewed from the outside of the helicopter hangar. is a perspective view of the concertina door in a position corresponding to Fig. 13 showing the concertina door in a fully opened, stowed position at the top portion of the coaming, as viewed from the inside of the helicopter hangar. is a perspective view of the concertina door in a position corresponding to Fig. 13 and 16 but here as viewed from the outside of the helicopter hangar. Fig.18 is a schematic side view of a concertina door in its top, stowed

position, wherein the height of the top door panel is half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with equal protrusion lengths inside and outside of the coaming.

Fig. 19 is a schematic side view of a concertina door in its top, stowed

position, wherein the height of the top door panel is more than half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with an external protrusion length being less than its internal protrusion length relative to the coaming.

Fig. 20 is a schematic side view of a concertina door in its top, stowed

position, wherein the height of the top door panel is less than half of the height of each of the other door panels, so that the folded door in its top stowed position protrudes horizontally with an external protrusion length exceeding its internal protrusion length relative to the coaming.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

The invention will now be described with reference to embodiments of the invention and with reference to the appended drawings. With initial reference to Fig. 1 , this figure shows a cut-out perspective view of a top-hinged foldable concertina door 1 according to the present invention. The concertina door 1 is shown in a closed position and comprises a top door panel 2, a mid-door panel 3 and a bottom door panel 4 that are arranged to seal a coaming 5. The top panel 2 is hinged in a top portion 6 of the coaming 5 and hinged to the mid-door panel 3 which in turn is hinged to the bottom door panel 4. The door 1 is provided with a compressible sealing gasket 7 arranged to seal against the coaming 5 when the door 1 is closed. The sealing gasket 7 will be shown in enlarged views below with reference to Figs. 4 and 5 and is only faintly indicated in the overview presented in Fig. 1 . There may alternatively be more than one mid-door panel 3, depending on the size and proportions of the door 1 , although only one mid-door panel 3 is shown in the drawings.

Fig. 2 shows a broken side view of a marine vessel 8, more particularly a naval vessel with a flight deck 9 for a helicopter 10 and a helicopter hangar 1 1 having a concertina door 1 according to the invention. The helicopter 10 is used as a general representative of any applicable aircraft, such as pilotless drones or VTOL (Vertical Take-Off and Landing) aircraft, which may take-off and land on the flight deck 9 and then be stored in the hangarl 1 . As shown in the figure, the door 1 may 5 also be used in other positions on the marine vessel 8 - for example as a mission bay door as indicated in the hull 13 below the flight deck 9. Hence, the door 1 may favourably be used both in the superstructure 12 and the hull 13 of the marine vessel 8 as the robust construction of the door 1 is well capable of withstanding the demanding operational conditions of a naval vessel.

10

Fig. 3 shows a simplified and geometrically exaggerated schematic view of a concertina door 1 as seen from inside the helicopter hangar 1 1 . The door 1 is shown in a closed position and also in a partially open position indicated by dashed lines. The figure clearly shows that the door 1 and the coaming 5 have

15 slanting sides 14 forming a wedge-shaped door opening 15 with a downwardly narrowing width. The door 1 is arranged, in an initial opening stage, to be raised linearly relative to the coaming 5 with the door panels 2, 3, 4 maintained in a common plane (i.e. the plane of the paper sheet of the figure) for a linear raising height, h, which in turn creates a gap, g, between the door 1 and the coaming 5

20 allowing the sealing gasket 7 to uncompress and disengage from the slanting sides 14 of the coaming 5. In the figure, the door 1 in its linearly raised position is indicated by a dashed contour line 16. After this initial opening stage, the door panels 2, 3, 4 are arranged to be folded in a secondary opening stage into a stowed, fully folded position at the top portion 6 of the coaming 5, which will be

25 described In greater detail below with reference to Figs. 7 through 20. The slanting angle, a, of the slanting sides 14 are between 2 and 10 degrees and preferably between 4 and 6 degrees. As seen in Fig. 1 , the linear raising distance, h, in the initial opening stage is less than 10% of the height of the door opening 15. For example, the linear raising distance, h, in the initial opening stage may typically be

30 200mm for a typical size helicopter hangar 1 1 . As further illustrated in Fig. 3, the bottom door panel 4 is provided with a lower guide pin 17 protruding horizontally outwards from each slanting side 14. The guide pins 17 are arranged in a lower half section of the bottom door panel 4 and are each adapted to slide within a lower side guiding console 18 having a first linear guide section 19 oriented in the plane of the door opening 15 and directed perpendicularly upwards with respect to a horizontal bottom edge 20 of the coaming 5. A second angled guide section 21 is arranged at an angle to said first linear guide section 19. Hence, the first linear guide section 19 is arranged to guide the door 1 linearly upwards in the initial opening stage, whereas the angled guide section 21 initiates the folding movement of the door panels 2, 3, 4. In the simplified, schematic view of Fig. 3, the lower side guiding consoles 18 are illustrated as being slightly angled to the left and right, respectively, in a direction towards the viewer for the sake of demonstrative illustration only, although in reality they would both be directed perpendicularly inwards from the plane of the drawing toward the viewer and the inside of the helicopter hangar 1 1 , which is clearly shown in the following drawings that depict the actual design according to a favourable embodiment of the invention.

With further reference to the simplified view of Fig. 3, the door 1 is prevented from folding in its closed lowered position by means of an auto-cleat system including upwardly open, U-shaped cleats 22 positioned on each slanting side 14 of the coaming 5 at heights corresponding to a horizontal hinge axis 23 between the top door panel 2 and the mid-door panel 3 as well as a horizontal hinge axis 24 between the mid-door panel 3 and the bottom door panel 5. The cleats 22 are adapted to receive locking pins 25 protruding from the slanting sides 14 of the door 1 at said hinge axes 23, 24. These locking pins 25 are held within the cleats 22 in said closed lowered position of the door 1 and during the initial linear opening stage of the door 1 . In the closed position, the bottom door panel 4 is further secured vertically into the flight deck 9 by means of two vertical locking pins 26 that are received within two corresponding locking cavities 27 in said flight deck 9. In the shown exemplifying embodiment, the linear movement of the door 1 in the initial opening stage is effected with a pair of hydraulic, pneumatic or electric actuators 28 via over-center linkage mechanisms 29 linked to the top door panel 2, arranged to positively lock the door 1 in a closed position. This will be further described below with reference to Fig. 6 and onwards. The linear movement of the door 1 may alternatively be effected in other well-known ways, for example by actuators arranged to push the door 1 upwards (not shown).

Still with reference to Fig. 3, each door panel 2, 3, 4 is arranged to rotate about a horizontal pivot spindle 30 protruding sideways from each slanting panel side 14, said pivot spindles 30 being movably guided within straight side guide rails 31 arranged on each side of the door 1 . The side guide rails 31 extend perpendicularly upwards with respect to the horizontal bottom edge 20 of the coaming 5. In the shown schematic example, the pivot spindles 30 slide within the side guide rails 31 by mean of rollers 32 for reduced friction, but may alternatively slide by means of lubricated sliding blocks or similar (not shown).

The folding movement of the door 1 is - in the shown example - effected by a winch 33 provided on the inside of top door panel 2. The winch 33 is adapted to hoist and lower the folding door panels 2, 3, 4 by means of a system of wires 34 and pulleys 35 as diagrammatically shown in Fig. 3.

As is further seen in Fig. 3, the bottom door panel 4 may conveniently be provided with a crew door 36 and windows 37. The crew door may be opened when the rest of the concertina door 1 is in its closed position. The windows 37 enables crew members to monitor a helicopter landing from a protected position within the helicopter hangar 1 1 so as to determine when the landing is completed and it is safe to open the concertina door 1 . Of course, the crew door 36 may alternatively be positioned in the hangar wall next to the coaming 5 if so desired.

Fig. 4 shows an enlarged cut-out cross-sectional view taken along line IV-IV in Fig. 3 of the mid-door panel 3 and the coaming 5 with the door 1 in its closed position in which the sealing gasket 7 is compressed against the against a flat sealing surface 38 of the coaming 5. The sealing gasket 7 is made of an elastic, oil-and weather resistant polymer material and the shown example has three internal cavities 39. The sealing gasket 7 is here glued to a metal structure of the mid-door panel 3, partly within a recess 40. The shown cross-section of the mid-door panel is identical to the corresponding cross-sections of the top door panel 2 and the bottom door panel 4. Both the coaming 5 and the door-panels 2, 3, 4 are insulated with an internal insulation material 41 in the shown example. In other, not shown examples the door panels 2, 3, 4 may optionally be non-insulated depending on the position and use of the door 1 . The door 1 is also provided with a fire safety system including a heat-expanding sealing trim 42 positioned on the interior side (i.e. the lower side in the figure) of the compressible sealing gasket 7 relative to the coaming 5, said heat-expanding sealing trim 42 being arranged to expand and seal against the coaming 5 in case of a fire.

Fig. 5 shows a similar cross-sectional view as in Fig. 4, only here the door 1 is shown directly after its initial opening stage where the door 1 has been raised linearly and parted from the sides of the coaming 5 due to the wedge-shaped door opening. Now the sealing gasket 7 is uncompressed and has elastically reassumed its original shape, leaving the gap, g, between the sealing gasket 7 and the coaming 5 which allows the door panels 2, 3, 4 to be folded.

In Fig. 6, the concertina door 1 is shown in a side view in its closed position. The lower guide pins 17 are in the lowermost position within the lower side guiding console 18 and the horizontal locking pins 25 are secured in the U-shaped cleats 22 as described above with reference to Fig. 4. Furthermore, the door 1 is positively locked in its closed position by the over-center linkage mechanism 29. As can be clearly seen in the figure, an actuator rod 43 of the actuator 28 is arranged to push a knee-joint 44 between an upper linkage arm 45 and a lower linkage arm 46. Both the actuator 28 and the upper linkage arm 45 are hinged in an upper mounting console 47 attached which in this example is fixedly mounted to the roof 48 of the hangar 1 1 . The lower linkage arm 46 is hinged in the top door panel 2. The horizontal pivot spindle 30 of the top door panel 2 is shown in its lower position in an upper guiding console 49, which will be described in greater detail below with reference to Figs. 8 and 9, respectively. Fig. 7 shows a side view of the concertina door 1 in a position where the door panels 2, 3, 4 have just begun to fold after the initial linear opening stage. Hence, the lower guide pins 17 have now left the linear guide section 19 of the lower side guiding console 18 and have entered the angled guide section 2, which initiates the folding movement of the door 1 , as it has now been raised linearly by means of the actuator 28. As shown in the figure, the actuator 28 have now retracted its actuator rod 43, pulling the knee-joint 44 out of the over-center locking position and consequently moving the upper linkage arm 45 and the lower linkage arm 46 of the over-center linkage mechanism 29 so that the horizontal pivot spindle 30 of the top door panel 2 is shown in its upper position in the upper guiding console 49.

The upper guiding console 49 is shown in the broken, enlarged side view of Fig. 8. Here, the top door panel 2 and its upper guiding console 49 is shown with the concertina door in the position previously shown in Fig. 7 where the door panels 2, 3, 4 have just begun to fold. As shown in Fig. 8, the upper guiding console 49 is provided with a linear guiding slot 50 in which the horizontal pivot spindle 30 of the top door panel 2 is arranged to slide. In the shown position, corresponding to the one in Fig. 7, the horizontal pivot spindle 30 is in its top position within the linear guiding slot 50 and will remain there during the rest of the opening sequence, as this position forms the pivot point of the top door panel 2. Fig. 8 also shows the top door panel 2 being provided with a compressible horizontal top sealing gasket 51 mounted in a top recess 52. The top sealing gasket 51 is arranged to seal against an external wall section 53 extending along the top portion 6 of the coaming 5.

Fig. 9 shows a broken, enlarged side view of the top door panel and its upper guiding console 49 with the concertina door 1 in a closed position corresponding to the closed position previously shown in Fig. 6. Here, the horizontal pivot spindle 30 is in its lowermost position within the linear guiding slot 50 and the top sealing gasket 53 is compressed against the external wall section 53.

Fig. 10 is a perspective view of the concertina door 1 in its closed position corresponding to the side view in Fig. 6 as described earlier, here viewed in perspective from the inside of the helicopter hangar 1 1 . In the following figure, Fig. 1 1 , the door 1 is shown in a similar perspective view but with the door in a position where the door panels 2, 3, 4 have just begun to fold after the initial linear opening stage. This view corresponds to the position as shown earlier in the side view of Fig. 7. In the shown embodiment, the top door panel 2 is arranged to be pivoted at its top edge whereas the other door panels 3, 4 are arranged to be pivoted at half their height. The top door panel 2 is arranged to be pivoted inwards towards the inside of the coaming 5 and towards the inside of the helicopter hangar 1 1 . In Fig. 12, the concertina door 1 is shown in a position where the door panels 2, 3, 4 are folded 45 degrees and is in the folding process ending in the fully opened, stowed position at the top portion 6 of the coaming 5 as shown in Fig. 13.

Fig. 14 is a perspective view of the concertina door 1 in a position corresponding to Fig. 12 where the door panels 2, 3, 4 are folded 45 degrees as viewed from the inside of the helicopter hangar 1 1 . A corresponding perspective view of the door 1 from the outside of the helicopter hangar 1 1 is shown in Fig. 15.

Fig. 16 is a perspective view of the concertina door 1 in a position corresponding to Fig. 13 showing the door 1 in a fully opened, stowed position at the top portion 6 of the coaming 5, as viewed from the inside of the helicopter hangar 1 1. Fig. 17 is a perspective view of the concertina door 1 in a position corresponding to Fig. 13 and 16 but here as viewed from the outside of the helicopter hangar 1 1 . In the stowed position, the door 1 according to the invention may protrude from the coaming 5 both inwards and outwards and therefore make efficient use of "dead volume" that would otherwise be unusable, as will be described with reference to Figs 18 through 20 below. Thus, Fig 18 is a simplified schematic side view of a concertina door 1 in its top, stowed position, where the height of the top door panel 2 is half of the height of each of the other door panels 2, 3. Hence, the folded door 1 in its top stowed position protrudes horizontally with equal protrusion lengths L _ex t _, L _in t inside and outside of the coaming 5.

Fig. 19 shows another embodiment in a similar schematic view, where the height of the top door panel 2 is more than half of the height of each of the other door panels 2, 3. In this embodiment, the folded door 1 in its top stowed position protrudes horizontally with an external protrusion length L _ex t being less than its internal protrusion length L _in t relative to the coaming 5.

Finally, in Fig. 20, yet another embodiment is shown, where the height of the top door panel 2 is less than half of the height of each of the other door panels 3, 4. Here, the folded door 1 in its top stowed position protrudes horizontally with an external protrusion length L _ex t exceeding its internal protrusion length L _in t relative to the coaming 5.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings and a skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

LIST OF REFERENCE NUMERALS USED IN THE ACCOMPANYING DRAWINGS

I . Concertina door

2. Top door panel

3. Mid-door panel

4. Bottom door panel

5. Coaming

6. Top portion of the coaming

7. Compressible sealing gasket

8. Marine vessel

9. Flight deck

10. Helicopter

I I . Helicopter hangar

12. Superstructure

13. Hull

14. Slanting sides of door and coaming

15. Wedge-shaped door opening

16. Contour of linearly raised position of the door

17. Lower guide pins

18. Lower side guiding console

19. Linear guide section

20. Horizontal bottom edge of the coaming

21 . Angled guide section

22. U-shaped cleats

23. Horizontal hinge axis

24. Horizontal hinge axis

25. Horizontal locking pins

26. Vertical locking pins

27. Locking cavities

28. Actuator

29. Over-center linkage mechanisms 30. Horizontal pivot spindle

31 . Side guide rails

32. Rollers

33. Winch

34. Wires

35. Pulleys

36. Crew door

37. Window

38. Flat sealing surface

39. Internal cavities in sealing gasket

40. Recess for sealing gasket

41 . Insulation material

42. Heat-expanding sealing trim

43. Actuator rod

44. Knee-joint of over-center mechanism

45. Upper linkage arm

46. Lower linkage arm

47. Upper mounting console

48. Roof of the helicopter hangar

49. Upper guiding console

50. Linear guiding slot

51 . Compressible horizontal top sealing gasket

52. Top recess

53. External wall section along top portion of the coaming

a: Slanting angle

g: Gap between door panels and coaming after initial opening stage h: Raising height after initial opening stage