Hinge system for airfoil

Abstract

A foil hinge system for a hydrofoil or airfoil includes a main foil body 1, substantially extending in a longitudinal direction L and a transverse direction T, a flap 2 hinged to the main foil body 1 arranged on a longitudinal end side of the main foil body 1, and a flexible element 3 connecting the main foil body 1 and the flap 2. Several rigid structures 4, 5 are arranged in such a manner on the flexible element 3, that they provide a dead stop when the flap 2 is in a maximum deflection with respect to the main foil body 1.

Claims

1. A foil hinge system for a hydrofoil or airfoil, comprising: a main foil body, substantially extending in a longitudinal direction and a transverse direction, a flap hinged to the main foil body arranged on a longitudinal end side of the main foil body, and a flexible element connecting the main foil body and the flap, wherein several rigid structures are arranged in such a manner on the flexible element, that the rigid structures provide a dead stop when the flap is in a maximum deflection with respect to the main foil body.

2. The foil hinge system according to claim 1, wherein the rigid structures are shaped and arranged on the flexible element such that a gap is provided between the adjacent rigid structures, which enables movement of the flap relative to the main foil body.

3. The foil hinge system according to claim 2, wherein the rigid structures substantially extend in the transversal direction and the gap is provided in the longitudinal direction.

4. The foil hinge system according to claim 1, wherein the flexible element substantially extends in a longitudinal direction and transverse direction and connects the main foil body and flap in the longitudinal direction, wherein the rigid structures are provided in a spanwise direction on both sides of the flexible element.

5. The foil hinge system according to claim 1, wherein the flexible element is made of a thin flexible composite sheet.

6. The foil hinge system according to claim 1, wherein the flexible element is made of an anisotropic material.

7. The foil hinge system according to claim 1, wherein flexible element is made of a composite sheet material, whose fiber direction orientation and/or laminate thickness is altered locally.

8. The foil hinge system according to claim 1, wherein at least three rigid structures are arranged on the flexible element.

9. The foil hinge system according to claim 1, wherein the rigid structures have a wedge-like form increasing the longitudinal width of the rigid structures in the spanwise direction towards the flexible element, wherein when the flap is in a central position, the adjacent surfaces of two adjacent rigid structures are arranged in an angle (a) to each other.

10. The foil hinge system according to claim 1, wherein an elastic cover is provided between the main foil body and flap and covers the rigid structures.

11. The foil hinge system according to claim 10, wherein the elastic cover comprises a boundary elastomer which is directly arranged on the rigid structure and an outside elastomer which is arranged on the boundary elastomer.

12. The foil hinge system according to claim 10, wherein the elastic cover provides a continuous surface between the flap and main foil body.

13. The foil hinge system according to claim 1, wherein chamfers are provided at the longitudinal end sides of the main foil body and/or flap, which are adjacent to the flexible element.

14. The foil hinge system according to claim 1, wherein the rigid structures are adapted to come into contact with respective adjacent rigid structures when the flap is in a maximum deflection regarding the main foil body.

15. An airfoil or Hydrofoil comprising a foil hinge according to claim 1, wherein the flap is a leading edge flap, trailing edge flap, aileron or trim tab.

16. The foil hinge system according to claim 1, wherein a plurality of the several rigid structures are disposed on a first side of the flexible element and a plurality of the several rigid structures are disposed on a second side of the flexible element that is opposing the first side.

17. The foil hinge system according to claim 1, wherein each of the several rigid structures has an elongated length that extends in the transverse direction, a width that extends in the longitudinal direction, and a height that extends normal to the transverse direction and the longitudinal direction, the length of each of the several rigid structures being greater than the width or the height.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be further explained with reference to an exemplary embodiment as shown in the figures.

(2) FIG. 1 shows a sectional side view of an embodiment of a foil hinge system according to the invention.

(3) FIG. 2 shows a perspective sectional view of the embodiment according to FIG. 1.

(4) FIG. 3 shows different deflection states of the flexible element and flap of the foil hinge system according to FIG. 1 in a sectional view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) FIG. 1 shows a foil hinge system according to an embodiment of the invention. The foil hinge system may be used in a hydrofoil or an airfoil with a streamline shape as shown in FIG. 1. However, in other embodiments, the foil hinge system may also be used in air foils or hydrofoils of other types, for example, for foils that comprise a leading edge flap, a trailing edge flap, an aileron or trim tab.

(6) The foil hinge system comprises a main foil body 1 substantially extending in a longitudinal direction L and transverse direction T. The main foil body 1 has a thickness perpendicular to the transverse and longitudinal direction, which is smaller than the extension of the main foil body in the longitudinal and transverse directions.

(7) The flexible element 3 is inserted in a groove in the longitudinal end side of the main foil body. Also, the flexible element 3 is inserted in a groove in the longitudinal end side of the flap. The flexible element 3 may be fixed by adhesive and/or mechanical fasteners in the respective grooves. In other embodiments, the flexible element may be laminated as an integral part of either the flap or the main foil body. Further alternatively, the main foil body, flexible element and flap may all be laminated as one piece.

(8) The foil hinge system further comprises a flap 2, which is movable with respect to the main foil body 1. For this purpose, the foil hinge system comprises a flexible element 3 connecting the main foil body 1 and the flap 2. The flexible element 3 is adapted to be bent substantially around the transverse direction T as shown for different articulation states in FIG. 3, such that the flap 2 can be brought into different articulations regarding the main foil body 1. This in particular serves the purpose that the flow of air or water around the foil hinge system may be actively controlled, or that the foil hinge system may passively adapt to external flow conditions.

(9) In particular, the flexible element 3 is made of a thin flexible laminate composite sheet (LCS) connecting the main foil body 1 and the flap 2. This sheet may have a locally or a directionally different stiffness in order to provide the desired curvature when being bent. The desired distribution of stiffness can be effected by using anisotropic material such as carbon fiber and altering the fiber orientation and/or laminate thickness within the flexible element 3.

(10) Several rigid structures 4 are provided on one side of the flexible element 3, and several rigid structures 5 are provided on the other side of the flexible element 3. In particular, the several rigid structures 4, 5 are spanwise rigid structures (SRS) that are laminated in a spanwise direction to the top and bottom of the flexible element 3, which is formed as a flexible composite sheet.

(11) The several rigid structures 4, 5 are shaped in a manner that gaps 6, 7 are provided between them when the flexible element 3 is in an unarticulated position. These gaps 6, 7 serve the purpose of stabilizing the foil hinge system and limiting the curvature of the flexible element 3 in the maximum articulation of the flap 2, as shown in FIGS. 3a and 3g.

(12) In addition to the gaps 6, 7 between the rigid structures 4, 5, gaps 8, 9, 10, 11 may be provided between the respective outer rigid structure and the adjacent main foil body 1 or flap 2. The gaps 6, 7, 8, 9, 10, 11 define several discrete hinge lines in the flexible element 3 along which bending is possible. Thus, they enable a defined movability of the flexible element 3. This enables that defining and ensuring the maximum allowed bend of the flexible element 3, and a well defined movement of the flexible element 3 and the flap 2 according to required properties in between the maxima.

(13) The according angles are also provided between the main foil body 1 and the adjacent rigid structures 4, 5 and the flap 2 and the adjacent rigid structures 4, 5 in the respective gaps 8, 9, 10, 11. In particular, the side walls of each of the gaps 6, 7, 8, 9, 10, 11 define a respective angle , which may be different for each gap. The angle defines the maximum bending at the hinge line defined by the respective gap 6, 7, 8, 9, 10, 11. The addition of all angles at one side of the flexible element defines the maximum articulation of the flap 2.

(14) On the rigid structures 4, 5 and between the main foil body 1 and the flap 2, a boundary elastomer 12, 14 is provided. On the boundary elastomer 12, 14, an outside elastomer 13, 15 is provided, which enables a continuous and smooth surface between the main foil body 1 and the flap 2. In particular, the outside elastomer 13, 15 is flush with the surface of the main foil body 1 and the flap 2. The boundary elastomer 12, 14 and the outside elastomer 13, 15 form together an elastic cover on each side of the foil hinge system. In other embodiments, providing one elastomer layer only for the elastic cover on each side of the flexible element 3 is sufficient. However, the different layers for the outside elastomer 13, 15 and the boundary elastomer 12, 14 enable to use different materials or materials with different characteristics. For example, it may be possible to choose a more soft material for the boundary elastomer 12, 14, while providing a thinner but more resilient material for the outside elastomer 13, 15. The material of the outside elastomer 13, 15 has to withstand the environment, e.g. should not be negatively affected by seawater or UV light. A uniform surface finish can be applied over the entire foil hinge system including the region of the flexible element and thus a smooth continuous surface can be attained. Thus, the foil hinge system has a continuous and uniform surface with the foil and main foil body.

(15) Furthermore, the properties of the elastic cover, in particular the properties of the boundary elastomer 12, 14 and outside elastomer 13, 15 may be varied so as to precisely determine the static and dynamic behaviour of the articulated foil surfaces.

(16) In FIG. 3, several articulations of the flap with respect to the main foil body 1 are shown. FIG. 3d shows the central unarticulated position of the flap 2 with the flexible element 3 being straight. FIG. 3a shows a maximum articulation of the flap 2 towards the top. As can be seen in FIG. 3a, all the upper gaps 6 between the rigid structures 4 and the gaps 8, 9 between the outer rigid structures and the main foil body 1 and respectively the flap 2 are closed, and in particular the side surfaces of the rigid structures 4 are in surface contact with each other.

(17) Thus, the several rigid structures provide a dead stop for the flap and prevent further upward movement. The same situation is shown for the maximum deflection of the flap 2 in the lower direction in FIG. 3g.

(18) FIGS. 3c and 3b show an increasing articulation of the flap 2 with respect to the main foil body 1 toward the state as shown in FIG. 3a. FIGS. 3e and 3f show an increasing articulation of the flap 2 with respect to the main foil body 1 toward the state as shown in FIG. 3g.

(19) It is emphasized that the angles for each of the gaps 6, 7, 8, 9, 10 or 11 may be different and chosen as required by a particularly required static and dynamic behaviour of the foil hinge system. In some embodiments all angles for the upper gaps 6, 8, 9 may be the same and/or all angles for the lower gaps 7, 10, 11 may be the same. In some embodiments all angles of all gaps 6, 7, 8, 9, 10 or 11 may be the same.

(20) While in the present embodiment the foil hinge system was shown to comprise an entire main foil body and flap, the foil hinge system may also be provided as a system that is connected to a foil and flap, by essentially only providing the hinge and connector parts for the foil and flap.

(21) In the present embodiment, the several rigid structures are arranged such that, at the flexible element 3, they are substantially in contact with each other. This enables clearly specified discrete hinge lines on the flexible element 3. However, in other embodiments, it is also possible that a certain distance is provided between the rigid structures on the flexible element, allowing discrete portions of the flexible element 3 in between the rigid structures to be freely curved.