DESCRIPTION

The invention relates to a propulsion device for a vessel, comprising an essentially upright hollow wing provided with a wall portion having an essentially circular shape, as viewed transversely to the longitudinal axis of the hollow wing, wherein air inlets are provided in the wing wall portion at mutually substantially separated locations, wherein a shut-off member is provided, which is able to open and to close the air inlets by means of rotation around the centre of the circular wing wall portion, so that when one air inlet is open, the other is closed and vice versa. The present type of propulsion device is often referred to by the term "Turbosail" (see for example https://en.wikipedia.org/wiki/Turbosail).

This type of propulsion device is known from patent document US4630997A in the name of Jacques Cousteau et al, in which the operation is discussed in full detail.

Object of the present invention is to provide a simple and yet very reliable configuration for the shut-off member for the air inlets, which (also) under heavy climatic and operational conditions at sea (strong wind, salt water, etc.) will continue to function properly.

In order to achieve the object of the invention, a propulsion device for a vessel is provided, comprising an essentially upright hollow wing provided with a wall portion having an essentially rounded profile (hereinafter: circular shape; in 3D, therefore having an essentially cylindrical shape) in which wall portion, at mutually substantially separated locations (A, B), one or more air inlets are provided, extending one above the other, wherein furthermore one or more shut-off members are provided, extending one above the other, the shut-off members being connected to, or forming part of, a displacement frame driven by displacement means, the device being arranged in such a way that, by means of rotation of the displacement frame, the one or more air inlets, extending one above the other at the mutually separated locations, are closed and opened by the one or more shut-off members, wherein the one or more shut-off members comprise a shut-off tarpaulin (sail) of flexible material contained in a mounting frame. The invention is based on the insight that a shut-off tarpaulin/sail in itself can be moved easily along the surface of the cylindrical wing wall portion, since during that movement the shut-off tarpaulin is not or hardly pressed against the wing wall, while the shut-off tarpaulin is pressed against the air inlets under the influence of, on the one hand (on the side of the wing wall/air inlet) the negative pressure/suction force of the air extraction that is connected to the air inlets (see the aforementioned patent) and on the other hand the normal air pressure of the ambient air.

Preferably, the one or more air inlets comprise air inlet gratings, wherein the outer surface of the gratings adjoins the outer surface of the surrounding wing wall portion, as a result of which the shut-off tarpaulins are retained by (the outer surface of) the air inlet gratings and thereby effect a good closure.

As is known from, and discussed in detail in, the aforementioned patent, the device of the present type preferably comprises one or more wind deflection members connected to the one or more shut-off members, the wind deflection members being simultaneously displaced with the shut-off members along the cylindrical portion of the wing surface.

Preferably, the wind deflection members, as viewed transversely to the longitudinal axis of the hollow wing, have an outer shape substantially conforming to the shape of a V, preferably with inwardly curved flanks, wherein the centre of the V-shape extends outwardly from the wing wall and, wherein the shut-off tarpaulins extend between the flanks of the V-shape, which flanks widen relative to each other.

The invention will now be discussed in more detail with reference to the figure description below.

Figure 1 shows an exemplary embodiment of a device according to the invention.

Figure 1 shows an exemplary embodiment of a propulsion device according to the invention, comprising an essentially (schematically and in cross-section) upright hollow wing 1 provided with a wall portion la having an essentially circular shape, as viewed transversely to the longitudinal axis of the hollow wing 1. At mutually substantially separated locations, A and B respectively, the hollow wing is provided with a number of air inlets 2 extending one above the other (see figure Id). Furthermore, a number of (see figure lc) shut-off members 3 is provided, extending one above the other, the shut-off members being connected to, or forming part of, a displacement frame 4, driven by displacement means (not shown).

The device being arranged in such a way that, by means of rotation (see arrows 5) of the displacement frame 4 around an axis of rotation 6, the air inlets 2, extending one above the other at the mutually separated locations A and B, are closed and opened by the shut-off members 3 in alternating operation (compare the figures la and lb).

The shut-off members 3 comprise a mounting frame 3a which is arranged for holding (containing) (the side of) a shut-off tarpaulin 7 of a flexible material, the shut-off tarpaulin being arranged and dimensioned to be able to close to the respective underlying air inlet 2.

The embodiment of figure 1 shows air inlet gratings 2a of the air inlets 2. The outer surface of the air inlet gratings adjoins the outer surface of the surrounding outer wall of the wing 1. The air inlet gratings 2a ensure, inter alia, that the shut-off tarpaulin 7 of the shut-off members 3 cannot be sucked far inside the air inlets 2 but are supported against said gratings, so that a good closure of the air inlets 2 is achieved.

The device further comprises wind deflection members 8, which are connected to the shut-off members 3. In the exemplary embodiment shown, the wind deflection members 8 and the shut-off members 3 are integrated. The wind deflection members 8 partly function as a mounting frame 3a for holding the shut-off tarpaulin 7.

The outside of the wind deflection members 8, as viewed transversely to the longitudinal axis 6 of the hollow wing 1, is provided with an outer shape essentially corresponding to the shape of a V, preferably with inwardly curved flanks 8a, wherein the centre 8b (the tip) of the V-shape extends outwardly from the wing wall, wherein the shut-off tarpaulins 7 extend between the flanks of the V-shape, the flanks 8a widening relative to each other.

Finally, it is also noted that preferably a friction-reducing layer or structure (not shown) is provided on or against the inner surface of the shut-off tarpaulin 7 of the relevant shut-off member 3, or at least between the outer surface of the relevant air inlet gratings, or the outer surface of the wing wall portion between the locations A and B of the relevant air inlets 2, and the inner surface of the shut-off tarpaulin. All this is arranged and designed to reduce the friction between the inner surface of the shut-off tarpaulin and the outer surface of the relevant air inlet gratings 2a, and/or the outer surface of the wing wall portion la between the locations A and B, during the closing and opening of the relevant shut-off member 3 by means of rotation of the displacement frame 4. For example, the friction-reducing layer or structure is provided with a net structure, thereby achieving that in wet/damp conditions the shut-off tarpaulin 7 does not stick or remains stuck to the underlying surface - in particular the outer surface of the wing wall portion between the locations A and B - during the closing or opening of the shut-off member 3 by means of rotation of the displacement frame 4.

Accordingly, the present invention provides a fairly simple design of the shut-off members for the air inlets, which will continue to function properly and reliably, even under harsh climatic and operational conditions at sea.