EP4023545A1 - Folding propeller - Google Patents

Abstract

The present invention relates to a folding propeller (10), comprising a hub (2) which can be driven about an axis of rotation (A) via a drive shaft (4), at least two propeller blades (6a, 6b) which can be moved between a folded position (Z1) and an unfolded position (Z2) are arranged pivotably on the hub (2), and a propeller blade locking device (8) which is set up to lock the propeller blades (6a, 6b) in the unfolded position (Z2), the propeller blade locking device (8 ) is movable relative to the hub (2) in the direction of rotation (D) between an initial position (Z10) and a locking position (Z20).

Description

technical field

The present invention relates to a folding propeller which comprises a hub which can be driven in rotation about an axis of rotation via a drive shaft and has at least two propeller blades which are arranged on the hub such that they can be pivoted between a folded position and an unfolded position. Typically, such folding propellers are used in a motor drive for sailing boats.

State of the art

It is known to use auxiliary drives with folding propellers in sailing boats because of the advantageous flow properties when they are not used. As a rule, these are folding propellers which have two or more propeller blades which are mostly mounted transversely to the propeller hub and are essentially freely movable. This principle basically allows two operating states. The first operating state occurs when the propeller blades are folded in axially backwards, which occurs, for example, when the drive shaft is at a standstill. The second operating state occurs when the drive shaft rotates and is defined by the fact that the propeller blades are folded out radially outwards in order to be able to apply thrust to the boat in this way.

In the simplest case, the propeller blades fold apart due to centrifugal force both when driving forwards and when reversing. In most cases, the propeller blades are coupled to one another at their base end in order to ensure synchronous opening of the propeller blades. This avoids strong imbalances occurring on the drive shaft when the propeller blades are opened. If the folding propeller is turned in a direction that corresponds to forward travel, the thrust generated by the propeller blades pushes the propeller blades into a fully open position from a certain opening angle of the propeller blades. Consequently, both centrifugal force and thrust generate an opening moment on the propeller blades.

This works very well when driving forward. When reversing, on the other hand, it is more difficult to unfold the propellers, which reduces the efficiency of the known folding propellers when reversing. When reversing, the thrust generated at the propeller blades causes a closing moment on the propeller blades. If there is also a flow at the folding propeller that corresponds to forward travel, this flow also causes a closing moment on the propeller blades. Only the centrifugal force causes an opening moment and thus counteracts thrust and any incoming flow. As a result, the propeller blades often only reach a partially open position when reversing. Therefore, when reversing and especially when stopping, relatively high speeds are necessary in order to oppose the centrifugal force to the other closing torques. The efficiency of the folding propeller is therefore usually quite low when driving in reverse.

Presentation of the invention

Proceeding from the known prior art, it is an object of the present invention to provide an improved folding propeller.

The object is solved by a folding propeller with the features of claim 1. Advantageous developments result from the dependent claims, the description and the figures.

Accordingly, a folding propeller is proposed, comprising a hub which can be driven about an axis of rotation via a drive shaft, at least two propeller blades which are arranged on the hub such that they can be pivoted between a folded position and an unfolded position, and a propeller blade locking device which is set up to to lock the propeller blades in the deployed position.

According to the invention, the propeller blade locking device is movable relative to the hub in the direction of rotation between an initial position and a locking position.

The arrangement of the propeller blades on the hub, which can be pivoted between a folded-in position and a folded-out position, enables two operating states. When the propeller blades are in the folded-in position, the folding propeller is in a first operating state, in which the alignment of the propeller blades is oriented axially to the rear. This condition essentially only occurs when the drive shaft is at a standstill. When the propeller blades are in the unfolded position, the folding propeller is in a second operating state, which occurs when the drive shaft rotates. In this second operating state, the alignment of the propeller blades is oriented radially outwards. The folded position and/or the unfolded one Position can be predetermined end positions between which the propeller blades can be pivoted.

The pivotability of an individual propeller blade can be decoupled from the pivotability of other propeller blades, or the propeller blades can be coupled to one another in terms of pivotability. In particular, the folding propeller can have two or three propeller blades, the pivotability of which is decoupled from the pivotability of the other propeller blades or is coupled to this.

For purposes of the present disclosure, not all existing propeller blades need to be locked directly via the propeller blade locking device. Nevertheless, all existing propeller blades can be locked using the propeller blade locking device.

For the purposes of the present disclosure, a locking position is understood to mean a position of the propeller blade locking device relative to a propeller blade or to a plurality of propeller blades, in which the pivoting ability of the propeller blade or the propeller blades is restricted compared to the pivoting ability of the propeller blade or the propeller blades in the starting position.

The locking position can be a position in which the propeller blades are fully or partially folded out and are secured against folding in by the propeller blade locking device. In particular, the locking position can be a position in which the propeller blades are fully deployed and locked in this position by the propeller blade locking device such that no pivoting of the propeller blades can occur as long as the propeller blade locking device is in the locking position relative to the hub.

According to an advantageous development, the propeller blade locking device is connected to the drive shaft in a torsion-resistant manner, the hub being decoupled from the propeller blade locking device in the direction of rotation, the propeller blade locking device preferably having a sleeve.

According to this embodiment, the folding propeller thus has two components that can be moved relative to one another in the direction of rotation, the first component comprising the drive shaft and propeller blade locking device and the second component comprising the hub and the propeller blades.

As a result, the drive shaft and the propeller blade locking device can be designed as one component, which can be designed in one piece or can consist of several parts. Because the propeller blade locking device has a sleeve, the hub, which is decoupled from the propeller blade locking device in the direction of rotation, can be arranged inside the sleeve, for example. As a result, simple positioning and assembly of the hub, including the propeller blades pivotably arranged on the hub, can be guaranteed.

Advantageously, the hub is designed to be movable in such a way that when a torque is applied, the hub is forced to move from the starting position into the locking position.

The term forcing can mean that a stop is set between two parts that can be moved relative to one another.

For the purposes of the present disclosure, the term torque is to be understood as meaning a torque on the drive shaft from which a corresponding movement of the hub relative to the propeller blade locking device takes place.

In other words, the hub is designed together with the propeller blades arranged on it in such a way that when a torque is applied to the drive shaft and thus also to the propeller blade locking device connected to it in a torsionally rigid manner, the hub moves from the starting position to the locking position in which the propeller blades are locked , is enforced.

According to an advantageous development, the hub can be designed to be movable such that a movement of the hub from a starting position into a locking position in which the propeller blades are locked is forced by utilizing a torque exerted on the hub by the propeller blade locking device.

The torque of the drive shaft and the propeller blade locking device acts against the inhibition which is built up by the - at least partially - unfolded propeller blades, so that the propeller blade locking device is forced against the hub by the application of the torque in such a way that the aforementioned movement is achieved.

According to an advantageous development, the hub can be designed to be movable in such a way that, by utilizing the mass inertia of the hub, the hub is forced to move from the starting position into the locking position in which the propeller blades are locked.

As a result, the mass inertia of the hub and the propeller blades arranged thereon can be used to support the movement of the propeller blade locking device into the locking position when a relative acceleration is applied between the components which are decoupled from one another.

Mass inertia is generally understood to be a moment of inertia, also called mass moment of inertia or inertial moment, which indicates the inertia of a relevant body with respect to a change in its angular velocity during rotation around the axis of rotation (torque divided by angular acceleration).

Utilization of inertia means that essentially inertia is responsible for the movement of the propeller blade locking device from its starting position to its locking position, relative to the hub. This can be done, for example, in that an inert body, whose mass inertia is used to force the hub into the locking position when the rotation of the hub is accelerated, has a sufficient mass and a suitable bearing. How this is to be carried out in detail also depends on the angular velocity and the dimensions, which can be determined using simple tests. It is crucial that for a specific application from a desired angular acceleration of the drive shaft and the propeller blade locking device, the hub is placed in the locking position due to its mass moments of inertia relative to the propeller blade locking device.

According to another advantageous development, the hub is connected to the drive shaft in a torsionally rigid manner, with the propeller blade locking device being decoupled from the hub in the direction of rotation, with the propeller blade locking device preferably having a sleeve.

In this embodiment, for example, only the propeller blade locking device is decoupled in the direction of rotation, with the drive shaft, the hub and the propeller blades pivotably arranged on the hub being connected to one another in a torsionally rigid manner. This has the advantage that the power flow from the shaft to the propeller blades remains unchanged, which means that a redesign of the drive train can be avoided.

In this embodiment, the sleeve can preferably be arranged on the outside of the hub. This allows the propeller blade locking device to be easily integrated into a hub without having to make substantial modifications to the hub. Furthermore, the propeller blade locking device can be integrated into the hub without the flow in the Proximity of the folding propeller is significantly influenced by the propeller blade locking device. Finally, a sleeve is a cost-effective component that is easy to produce and that can easily be replaced or retrofitted if necessary.

In a further development, it is advantageous if the propeller blade locking device is designed to be movable in such a way that a movement of the propeller blade locking device from an initial position into a locking position in which the propeller blades are locked is forced by utilizing a mass inertia that occurs when the hub rotates.

In this embodiment, a mass inertia is essentially responsible for the movement of the propeller blade locking device from its starting position into its locking position, relative to the hub. For this purpose, a sufficient acceleration or a sufficient angular acceleration must be present, which leads to the relative movement being carried out.

In a further development, it can be advantageous if the propeller blade locking device is designed to be movable in such a way that its mass inertia is specifically used to force the movement of the propeller blade locking device from the starting position into the locking position.

As a result, the locking function can be guaranteed solely by the propeller blade locking device. Furthermore, the propeller blade locking device can thus be designed as a retrofit component with which conventional folding propellers can be equipped. In addition, the other components of the folding propeller do not have to be modified, or only slightly so, in order to ensure the locking function of the propeller blades.

According to an advantageous development, the effect of the mass inertia of the propeller blade locking device can optionally be supported or replaced by flow bodies that generate flow forces. Such flow bodies can be wings, ribs, lamellae or other devices on the propeller blade locking device. These airfoils are preferably configured to resist a change in rotational speed (particularly in the reverse direction) similar to the inertia of the propeller blade lock to keep the propeller blade lock stationary while the propeller spins backwards.

According to an advantageous embodiment, such flow bodies, in particular wings, can be designed to be collapsible or collapsible, so that they can nestle against the hub during forward rotation (low water resistance), while they move backwards line up to support inertia. This has the advantage that the propeller blades can be locked more reliably when turning backwards and that the flow body closes again during hydrogeneration because it then turns forward. Consequently, a direction-dependent intensification of that effect can be brought about that also causes the mass inertia.

According to an advantageous development, the direction of rotation corresponds to reverse rotation of the propeller blades. In principle, the propeller blades can be opened both when driving forwards and when driving backwards, ie in both directions of rotation.

If the propeller blades are driven via the drive shaft and set in rotation, they induce impulse forces on the adjacent fluid according to their blade geometry. When driving forwards, the opposing forces acting on the propeller blades increase the opening of the propeller blades. When reversing, on the other hand, it can happen that the counteracting forces that occur in the process cause an advancing moment on the propeller blades, which ultimately leads to the propeller blades folding into the folded position. This disadvantageous effect can be prevented by the propeller blade locking device.

Approaches are known from the prior art for adapting the profiles of the propeller blades in such a way that folding in of the propeller blades in reverse gear becomes less likely. For example, if the lift generated in reverse gear is lower, the speed must be correspondingly higher for a certain boost, which means that the correspondingly higher centrifugal forces make a collapse less likely. The presence of the propeller blade locking device has the advantage that the propeller blades can also be designed in such a way that high thrust is generated in reverse gear at low speeds, since folding into the folded position is indirectly prevented.

As a result, the propeller blades can be designed in such a way that they also generate optimal lift when reversing. This means that reverse travel can also be initiated effectively and reliably, even at low engine speeds. This eliminates the frequently used practice of particularly increasing the speed of the hub to initiate reverse travel in order to provide sufficient centrifugal forces. As a result, the folding propeller can be used in a more environmentally friendly, reliable and quiet manner.

Due to the fact that the locking position is enforced by utilizing a mass inertia that occurs when the hub rotates, a self-adjusting locking of the propeller blades can be achieved can be achieved, which takes place solely by rotating the hub. In addition, a controlled opening is guaranteed when reversing and when towing. This improves the efficiency and predictability of the folding propeller.

Furthermore, the efficiency of hydro-generation (recuperation), e.g. when sailing, can be improved by using the proposed lockable folding propeller. The hydro-generation operation can thus be carried out particularly efficiently.

In a further preferred embodiment, the propeller blades are mounted on a bearing journal arranged transversely to the axis of rotation. As a result, the propeller blades can be folded in parallel to the axis of rotation on the one hand and pivoted into a plane of rotation that is orthogonal to the axis of rotation on the other hand. Furthermore, the propeller blades of this design can be easily replaced and attached to the hub using commercially available bolts and/or locks.

According to an advantageous development, the propeller blade arresting device is designed such that it is in the starting position when the drive shaft is at a standstill, in which case the propeller blades can be freely pivoted between the folded position and the unfolded position. If there is no rotation of the drive shaft and no mass moment of inertia is thereby induced, the propeller blade locking device is in the starting position relative to the hub and the propeller blades of the folding propeller can pivot freely.

As a result, the propeller blade locking device does not appear as a locking component when the drive shaft is at a standstill, as a result of which the folding propeller behaves like a conventional folding propeller when the drive shaft is at a standstill. Consequently, established assembly, maintenance and cleaning work can be carried out in the same way.

According to an advantageous development, the sleeve of the propeller blade locking device has a recess and a latch in the region of each propeller blade, with the latch preferably being formed on a downstream end of the sleeve.

Within the meaning of the present application, an end of the sleeve is to be understood as meaning an end face of the sleeve in the axial direction. The downstream end of the sleeve is that end which is oriented downstream when the folding propeller is in forward motion. The recess is preferably a partial area cut out of the outer surface of the sleeve, in which a propeller blade or a propeller blade root of a propeller blade is accommodated in the unfolded position.

Preferably the latch is part of the sleeve. For example, the bolt is formed in that the recess on the lateral surface of the sleeve extends only partially up to the face of the downstream end of the sleeve. Preferably, the remaining gap between the end of the bar and the adjoining lateral surface of the sleeve is large enough that a propeller blade can be inserted and removed through this gap into the recess.

According to a particularly advantageous embodiment, in which the propeller blade locking device is connected to the drive shaft in a torsionally rigid manner, the opening of the propeller blades is effected or supported by the shape of the recess or the latch in such a way that the propeller blades are folded out by a form fit which is altered by the forces between the driven propeller blade locking device and the inertial hub.

In this way, it can be ensured in a simple manner that the sleeve is twisted relative to the propeller hub during rotation using mass inertia, is forced into the locking position and at the same time a bolt is pushed in front of each propeller blade.

In an advantageous embodiment, the propeller blade locking device has an insertion bevel that is designed in such a way that in a state in which the propeller blade locking device is not yet fully in the locking position, folding in the propeller blades results in the propeller blade locking device being reset to its starting position. Conversely, the incline causes the propeller blades to be pushed open by the incline when driving backwards.

For example, the insertion bevel can be designed on the bolt, in particular on one side of the bolt, which is at the same time an edge structure of the recess. For example, the bar can have a width that tapers towards its free-standing end, the width relating to a dimension that lies in the plane of the lateral surface. The reliability of the function of the propeller blade locking device is improved by the insertion bevels.

According to an advantageous development, the propeller blade locking device is made from one part. This allows the propeller blade locking device to be manufactured inexpensively. For example, the sleeve and bolt can be milled from one part, but in principle any type of primary shaping, in particular casting, forging or the like, is also conceivable. Alternatively, the sleeve and/or the bolt can also be connected with any type of joining. The locking bar can be adapted to the sleeve in the following shape or it can also be freely connected to it.

The propeller blade locking device and/or the propeller blades preferably have a metallic material. With regard to the propeller blade locking device, using a metallic material has the advantage that the mass moment of inertia of the same is increased. As a result, the reliability and predictability of the propeller blade locking device and ultimately the folding propeller with such is improved.

According to an advantageous development, the propeller blade locking device is designed to lock the propeller blades in an unfolded position during towing of the folding propeller, so that the propeller blades auto-rotate, the propeller blade locking device preferably being designed to allow the propeller blades to auto-rotate for energy recovery from a speed of about 5 knots . For example, the propeller blade locking device can have a recess and/or a latch for this purpose, which are designed in such a way that locking is also ensured when driving forward.

In an advantageous development, the propeller blades are designed in such a way that the initial opening of the propeller blades takes place using centrifugal force, preferably with the propeller blades having a metallic material, in particular a metal alloy. The initial opening of the propeller blades can take place from the initial folded position using centrifugal forces. On the one hand, a reliable and predictable function of the folding propeller can be achieved as a result. On the other hand, further technical means for opening the propeller blades can be dispensed with by utilizing centrifugal forces for the initial opening of the propeller blades. Consequently, the propeller blades can be freely pivoted on the hub.

The use of a metallic material for the propeller blades has the advantage that the initial opening of the blades, which is based on centrifugal force, is simplified by the corresponding mass of the propeller blades. This improves the reliability and predictability of the propeller blade locking device and ultimately the folding propeller with one.

• Die Propellerflügelarretiereinrichtung wird zusammen mit der Antriebswelle aus dem Stillstand heraus um eine Drehachse in einer Drehrichtung, die einer Rückwärtsfahrt entspricht, angetrieben.
• Durch die Winkelbeschleunigung der Propellerflügelarretiereinrichtung und der Massenträgheit der Nabe kann ein Kontakt zwischen Propellerflügelarretiereinrichtung und Nabe ausgebildet werden. Die Nabe kann alsdann zusammen mit den Propellerflügeln von der Propellerflügelarretiereinrichtung mitgeschleppt werden.
• Aufgrund von Fliehkräften, die an den Propellerflügeln angreifen, schwenken die Propellerflügel aus der anfänglichen, eingeklappten Position in eine ausgeklappte Position.
• Beim Herausschwenken in die ausgeklappte Position können die Propellerflügel jeweils in eine Aussparung der Propellerflügelarretiereinrichtung fahren, die eine entsprechende Öffnung ausbildet. Dabei können die Propellerflügel einen Riegel passieren, der etwa auf dem stirnseitigen Ende der Hülse ausgebildet sein kann.
• Nach Erreichen der ausgeklappten Position können sich die Propellerflügel vollständig in der Aussparung befinden.
• Verursacht durch die Drehung der Propellerflügelarretiereinrichtung kann das auf die Nabe und die ausgeklappten Propellerflügel ausgeübte Drehmoment dazu führen, dass die Propellerflügel innerhalb der Aussparung aus einer Ausgangsposition in eine Arretierposition bewegt werden. Die Arretierung kann letztlich durch einen Riegel erfolgen, der eine mittelbare Arretierung des Propellerflügels bewirken kann.
• Wird die Drehung angehalten, kann sich der Propellerflügel aufgrund der Massenträgheit der Nabe in die Ausgangsposition bewegen. Dabei ist insbesondere der Riegel so ausgestaltet, dass dieser den Propellerflügel, der sich in diesem Anschlag befindet, freigibt. Dadurch kann der Propellerflügel in diesem Anschlag aus der ausgeklappten Position in die eingeklappte Position zurückschwenken.

In order to explain the function of the propeller blade locking device in more detail using an example, an exemplary movement cycle of a folding propeller according to an embodiment is disclosed below, according to which the propeller blade locking device is connected to the drive shaft in a torsionally rigid manner and the hub is decoupled from the drive shaft in the direction of rotation:

• The propeller blade locking device is driven together with the drive shaft from a standstill about an axis of rotation in a direction of rotation that corresponds to reverse travel.
• Contact between the propeller blade locking device and the hub can be formed by the angular acceleration of the propeller blade locking device and the inertia of the hub. The hub can then be dragged along with the propeller blades by the propeller blade locking device.
• Due to centrifugal forces acting on the propeller blades, the propeller blades pivot from the initial folded position to an unfolded position.
• When swiveling out into the unfolded position, the propeller blades can each move into a recess in the propeller blade locking device, which forms a corresponding opening. In this case, the propeller blades can pass through a latch which can be formed, for example, on the front end of the sleeve.
• After reaching the deployed position, the propeller blades can be fully seated in the recess.
• Due to the rotation of the propeller blade locking device, the torque exerted on the hub and the deployed propeller blades can cause the propeller blades to be moved within the recess from a home position to a locked position. The locking can ultimately be done by a bolt that can bring about an indirect locking of the propeller blade.
• When the rotation is stopped, the propeller blade can move to the home position due to the inertia of the hub. In particular, the bolt is designed in such a way that it releases the propeller blade, which is located in this stop. In this way, the propeller blade can swivel back from the unfolded position to the folded position in this stop.

• Die Nabe wird über eine Antriebswelle aus dem Stillstand heraus um eine Drehachse in einer Drehrichtung, die einer Rückwärtsfahrt entspricht, angetrieben.
• Die Drehung der Nabe kann direkt auf die Propellerflügel übertragen werden, welche aufgrund von angreifenden Fliehkräften aus der anfänglichen, eingeklappten Position in eine ausgeklappte Position schwenken können.
• Beim Herausschwenken in die ausgeklappte Position können die Propellerflügel jeweils in eine Aussparung der Propellerflügelarretiereinrichtung fahren, die eine entsprechende Öffnung auf dem stirnseitigen Ende der Hülse ausbilden können. Dabei können die Propellerflügel einen Riegel passieren, der auf dem stirnseitigen Ende der Hülse ausgebildet sein kann.
• Nach Erreichen der ausgeklappten Position können sich die Propellerflügel vollständig in der Aussparung befinden.
• Verursacht durch die Drehung der Propellerflügel und der Nabe kann die Massenträgheit der Propellerflügelarretiereinrichtung dazu führen, dass die Propellerflügel innerhalb der Aussparung aus einer Ausgangsposition in eine Arretierposition bewegt werden. Die Arretierung kann letztlich durch einen Riegel erfolgen, der eine mittelbare Arretierung des Propellerflügels bewirken kann.
• Wird die Drehung angehalten oder reduziert, kann sich die Propellerflügelarretiereinrichtung aufgrund ihrer Massenträgheit in die Ausgangsposition bewegen. Dabei kann insbesondere der Riegel so ausgestaltet sein, dass dieser den Propellerflügel, der sich in diesem Anschlag befindet, freigeben kann. Dadurch kann der Propellerflügel in diesem Anschlag aus der ausgeklappten Position in die eingeklappte Position zurückschwenken.

In embodiments in which the hub is connected to the drive shaft in a torsionally rigid manner and the propeller blade locking device is decoupled from the hub in the direction of rotation, the mode of operation is as follows:

• The hub is driven via a drive shaft from a standstill about an axis of rotation in a direction of rotation that corresponds to reverse travel.
• The rotation of the hub can be transmitted directly to the propeller blades, which can pivot from the initial folded position to an unfolded position due to centrifugal forces acting on them.
• When swiveling out into the unfolded position, the propeller blades can each move into a recess in the propeller blade locking device, which can form a corresponding opening on the front end of the sleeve. In this case, the propeller blades can pass through a latch which can be formed on the front end of the sleeve.
• After reaching the deployed position, the propeller blades can be fully seated in the recess.
• Due to the rotation of the propeller blades and the hub, the inertia of the propeller blade locking device can cause the propeller blades to be moved from a home position to a locked position within the recess. The locking can ultimately be done by a bolt that can bring about an indirect locking of the propeller blade.
• If the rotation is stopped or reduced, the propeller blade locking device can move to the home position due to its inertia. In particular, the bolt can be designed in such a way that it can release the propeller blade, which is located in this stop. In this way, the propeller blade can swivel back from the unfolded position to the folded position in this stop.

The functions of the propeller blade locking device described herein are intended to be exemplary and not limiting.

The object of the present invention is further achieved by means of a drive for a boat with a folding propeller as described herein. Furthermore, the object of the present invention is achieved by means of a boat with such a drive.

Short description of the figures

Figur 1

eine schematische Ansicht eines Faltpropellers gemäß einer ersten Ausführungsform in einer eingeklappten Position;

Figur 2

eine schematische Ansicht des Faltpropellers gemäß der ersten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Ausgangsposition;

Figur 3

eine schematische Ansicht des Faltpropellers gemäß der ersten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Arretierposition;

Figur 4

eine schematische Ansicht eines Faltpropellers gemäß einer zweiten Ausführungsform in einer eingeklappten Position;

Figur 5

eine schematische Ansicht des Faltpropellers gemäß der zweiten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Ausgangsposition;

Figur 6

eine schematische Ansicht des Faltpropellers gemäß der zweiten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Arretierposition;

Figur 7

eine schematische Ansicht des Faltpropellers gemäß der zweiten Ausführungsform in einer Position, die zwischen der eingeklappten Position und der ausgeklappten Position liegt;

Figur 8

eine schematische Ansicht des Faltpropellers gemäß der zweiten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Ausgangsposition;

Figur 9

eine schematische Ansicht des Faltpropellers gemäß der zweiten Ausführungsform in einer ausgeklappten Position und einer Propellerflügelarretiereinrichtung in einer Arretierposition;

Figur 10

eine schematische Seitenansicht eines Faltpropellers gemäß einer dritten Ausführungsform in einer ersten Position;

Figur 11

eine schematische Seitenansicht des Faltpropellers gemäß der dritten Ausführungsform in einer zweiten Position; und

Figur 12

eine schematische perspektivische Ansicht eines Faltpropellers gemäß einer vierten Ausführungsform in einer ausgeklappten Position.

Preferred further embodiments of the invention are explained in more detail by the following description of the figures. show:

figure 1

a schematic view of a folding propeller according to a first embodiment in a folded position;

figure 2

a schematic view of the folding propeller according to the first embodiment in an unfolded position and a propeller blade locking device in an initial position;

figure 3

a schematic view of the folding propeller according to the first embodiment in an unfolded position and a propeller blade locking device in a locking position;

figure 4

a schematic view of a folding propeller according to a second embodiment in a folded position;

figure 5

a schematic view of the folding propeller according to the second embodiment in an unfolded position and a propeller blade locking device in an initial position;

figure 6

a schematic view of the folding propeller according to the second embodiment in an unfolded position and a propeller blade locking device in a locking position;

figure 7

a schematic view of the folding propeller according to the second embodiment in a position that lies between the folded position and the unfolded position;

figure 8

a schematic view of the folding propeller according to the second embodiment in an unfolded position and a propeller blade locking device in an initial position;

figure 9

a schematic view of the folding propeller according to the second embodiment in an unfolded position and a propeller blade locking device in a locking position;

figure 10

a schematic side view of a folding propeller according to a third embodiment in a first position;

figure 11

a schematic side view of the folding propeller according to the third embodiment in a second position; and

figure 12

a schematic perspective view of a folding propeller according to a fourth embodiment in an unfolded position.

Detailed description of preferred embodiments

Preferred exemplary embodiments are described below with reference to the figures. Elements that are the same, similar or have the same effect are provided with identical reference symbols in the different figures, and a repeated description of these elements is sometimes dispensed with in order to avoid redundancies.

In figure 1 1 is a schematic view of a folding propeller 10 according to a first embodiment in a folded position Z1.

The folding propeller 10 includes a hub 2 which is decoupled from the drive shaft 4 in the direction of rotation D. At the hub 2, two propeller blades 6a, 6b are pivotally mounted. The hub 2 can be driven via the drive shaft 4 about a schematically illustrated axis of rotation A, namely via a propeller blade locking device 8 which is connected to the drive shaft 4 in a fixed and therefore torsionally rigid manner.

Consequently, the hub 2 and the propeller blades 6a, 6b arranged on it form a first component which is mounted decoupled in the direction of rotation D in a further component consisting of the drive shaft 4 and the propeller blade locking device 8 .

The propeller blades 6a, 6b are between a folded position Z1 and an unfolded position Z2 (e.g. in figure 2 shown) pivotally mounted on the hub 2.

The propeller blade locking device 8 is set up to lock the propeller blades 6a, 6b in the unfolded position Z2, in order in this way to prevent (partial) folding in of the propeller blades 6a, 6b, for example when reversing, when stopping or during hydrogeneration. In this case, the propeller blade locking device 8 is designed as a sleeve 14 . The sleeve 14 has a recess 16 formed in its lateral surface and a latch 18 formed at the downstream end of the sleeve 14 . The sleeve 14 The propeller blade arresting device 8 formed here is, together with the drive shaft 4 fastened to it, relative to the hub 2 in the direction of rotation D between an initial position Z10 and an arresting position Z20 (e.g. in figure 3 shown) movable.

Correspondingly, a relative movement between the hub 2 and the sleeve 14 can be achieved by utilizing the torque exerted by the sleeve 14 on the hub 2, which occurs when the drive shaft 4 and thus the propeller blade locking device 8 in the form of the sleeve 14 rotates. The hub 2, together with the propeller blades 6a, 6b arranged on it, is impeded by its movement through the water, so that it accordingly provides a counter-torque and by the torque exerted on the propeller blade locking device 8 on the hub 2, a movement between the propeller blade locking device 8 and the hub 2 is caused. This allows a movement of the sleeve 14 relative to the hub 2 from a starting position Z10, as shown in figure 1 , to a Z20 detent position, as shown in figure 3 , to be forced.

In figure 2 1 is a schematic view of the folding propeller 10 according to the first embodiment in an unfolded position Z2, with the propeller blade locking device 8 still being in the initial position Z10 relative to the hub 2. In the figure 2 The representation shown corresponds approximately to the case that arises when the folding propeller 10 is in forward motion. Accordingly, the direction of rotation D is one that corresponds to forward travel.

The unfolding of the propeller blades 6a and 6b from the in figure 1 The folded-in position Z1 shown in the folded-out position Z2 is effected by rotating the drive shaft 4 together with the propeller blade locking device 8, which ultimately acts on the hub 2 via the propeller blades 6a, 6b. As soon as the propeller blades 6a, 6b are set in rotation, a centrifugal force or centrifugal force acts on them, which promotes the opening of the propeller blades 6a, 6b and thereby generates an opening moment on the propeller blades 6a, 6b. In addition, an opening moment acts on the propeller blades 6a, 6b when a rotation of the hub 2 is applied and the resulting simultaneous application of a forward thrust.

From the figure in figure 2 , in particular from the orientation of the blade profile, it can be seen that a rotation of the folding propeller 10 in the direction of rotation D generates a forward thrust S _V upwards in the drawing. The resulting counterforce acting on the propeller blades 6a, 6b supports the unfolding of the propeller blades 6a, 6b. In other words, they will Propeller blades 6a, 6b moved both by the centrifugal force and by reaction forces from the forward thrust generated by rotation in the unfolded position Z2.

Since the forward thrust S _V is applied to the drive shaft 4 in this direction of rotation D and no advancing torque acts on the propeller blades 6a, 6b, locking of the folding propeller 10 via the propeller blade locking device 8 is not provided and is also not necessary. At each point in time at which forward thrust is to be applied, the propeller blades 6a, 6b are driven into the unfolded position Z2.

Consequently remains in this state, as in figure 2 shown, the propeller blade locking device 8 in the form of a sleeve 14 typically in its initial state Z10. Alternatively or additionally, the propeller blade locking device 8 can also be designed in such a way that the folding propeller 10 is also locked via the propeller blade locking device 8 in the direction of rotation D, which corresponds to forward travel. In this way, the propeller blades 6a, 6b can be locked both by “sharp” turning backwards and by “sharp” turning forwards.

In figure 3 1 is a schematic view of the folding propeller 10 according to the first embodiment in an unfolded position Z2 and a propeller blade locking device 8 in a locking position Z20. In the figure 3 The illustration shown corresponds, for example, to the case that arises when the folding propeller 10 is driven in reverse. Accordingly, the direction of rotation D corresponds to that of reverse travel. Since in this direction of rotation D a feeding moment acts on the propeller blades 6a, 6b via the reverse thrust S _R - for example due to the flow of the surrounding water and the exertion of the backward thrust S _R directed in the closing direction of the propeller blades 6a, 6b - the feeding moment competes at Propeller blade with the centrifugal force acting on the propeller blade. Consequently, locking of the folding propeller 10 via the propeller blade locking device 8 is necessary or provided.

For this purpose, the proposed propeller blade locking device 8 in the form of a sleeve 14 and the hub 2 are designed in such a way that by utilizing the torque applied to the hub 2, which occurs when the drive shaft 4 rotates, a movement of the hub 2 relative to the sleeve 14 in the locking position Z20 is enforced. In this position, the propeller blades 6a, 6b are locked in the locking position Z20. The difference between the starting position Z10 and the locking position Z 20 can be clearly seen from a comparison of Figures 2 and 3 derive From this it can be seen that the change in the direction of rotation D from the Forward travel in reverse travel means that the sleeve 14 in the latter case, cf. figure 3 , is rotated relative to the hub 2 in such a way that the sleeve 14 adjoins the propeller blade 6a with another flank, namely with the opposite flank of the recess 16 in which the relevant propeller blade 6b is located. This takes place in that the torque exerted on the hub 2, which occurs when the drive shaft 4 rotates, is used to force a relative movement of the hub 2 relative to the sleeve 14 from an initial position Z10 into a locking position Z20.

In figure 4 a schematic view of a folding propeller 10 according to a second embodiment is shown in a folded position Z1.

The folding propeller 10 comprises a hub 2 which can be driven about an axis of rotation A via a drive shaft 4 (shown schematically). Furthermore, the folding propeller 10 comprises at least two propeller blades 6a, 6b, which can be moved between a folded position Z1 as shown and an unfolded position Z2 (for example in figure 5 shown) are arranged pivotably on the hub 2. In addition, the folding propeller 10 comprises a propeller blade locking device 8 which is movably coupled to the hub 2 and is set up to lock the propeller blades 6a, 6b in the unfolded position Z2 in order in this way to (partially) fold in the propeller blades 6a, 6b, for example when reversing, stopping or hydro-generation.

In this case, the propeller blade locking device 8 is designed as a sleeve 14 . The sleeve 14 has a recess 16 formed in its lateral surface and a latch 18 formed at the downstream end of the sleeve 14 . The locking bar 18 has an insertion bevel 20 . The propeller blade locking device 8 embodied as a sleeve 14 is in this case relative to the hub 2 in the direction of rotation D between an initial position Z10 and a locking position Z20 (e.g. in figure 6 shown) freely movable.

Correspondingly, a relative movement between the hub 2 and the sleeve 14 can be achieved by utilizing the mass inertia of the sleeve 14, which occurs when the hub 2 accelerates. A movement of the sleeve 14 from a starting position Z10, as shown in figure 4 , to a Z20 detent position, as shown in figure 6 , to be forced.

In figure 5 1 is a schematic view of the folding propeller 10 according to the second embodiment in an unfolded position Z2, with the propeller blade locking device 8 still being in the starting position Z10. In the figure 5 the representation shown corresponds approximately to that Case that occurs when the folding propeller 10 is in forward motion. Accordingly, the direction of rotation D is one that corresponds to forward travel.

The unfolding of the propeller blades 6a and 6b from the in figure 4 The folded-in position Z1 shown, into the unfolded position Z2, is effected by a rotation of the hub 2 and the centrifugal force acting above it on the propeller blades 6a, 6b. In addition, an opening moment acts on the propeller blades 6a, 6b when a rotation of the hub 2 is applied and the resulting simultaneous application of a forward thrust. In other words, the propeller blades 6a, 6b are moved to the unfolded position Z2 by the centrifugal force and the applied forward thrust.

Since in this direction of rotation D of the hub 2 no advancing moment acts on the propeller blades 6a, 6b in the forward thrust direction, locking of the folding propeller 10 via the propeller blade locking device 8 is not provided and also not necessary. At each point in time at which forward thrust is to be applied, the propeller blades 6a, 6b are driven into the unfolded position Z2.

Consequently remains in this state, as in figure 5 shown, the propeller blade locking device 8 in the form of a sleeve 14 typically in its initial state Z10. Alternatively or additionally, the propeller blade locking device 8 can also be designed in such a way that the folding propeller 10 is also locked via the propeller blade locking device 8 in the direction of rotation D, which corresponds to forward travel. In this way, the propeller blades 6a, 6b can be locked both by “sharp” turning backwards and by “sharp” turning forwards.

In figure 6 a schematic view of the folding propeller 10 according to the second embodiment is shown in an unfolded position Z2 and a propeller blade locking device 8 in a locking position Z20. In the figure 6 The illustration shown corresponds, for example, to the case that arises when the folding propeller 10 is driven in reverse. Accordingly, the direction of rotation D corresponds to reversing. Since in this direction of rotation D an advancing torque acts on the propeller blades 6a, 6b - for example due to the flow of the surrounding water and the exertion of the thrust directed in the closing direction of the propeller blades 6a, 6b - it is necessary or possible to lock the folding propeller 10 via the propeller blade locking device 8 . intended.

For this purpose, the proposed propeller blade locking device 8 is designed in the form of a sleeve 14 such that a movement of the sleeve 14 into the locking position Z20 is forced by utilizing the mass inertia of the sleeve 14 that occurs when the hub 2 accelerates. In this position, the propeller blades 6a, 6b are locked in the locking position Z20. The difference between the starting position Z10 and the locking position Z20 can be clearly seen from a comparison of the figures 5 and 6 derive From this it can be seen that the change in the direction of rotation D from forward travel to reverse travel results in the sleeve 14 in the latter case, cf. figure 6 , is rotated relative to the hub 2 such that the sleeve 14 abuts the propeller blade 6a. This takes place in that the inertia of the sleeve 14, which occurs when the hub 2 accelerates, is used to force a relative movement of the sleeve 14 from an initial position Z10 into a locking position Z20.

This is achieved not only when the direction of rotation is reversed, but each time the speed of the hub 2 increases in the direction of rotation which corresponds to reverse travel. For example, a rapid rotation of the hub 2 can cause the propeller blades 6a, 6b to straighten, and further acceleration of the rotation of the hub 2 can then cause the hub 2 to remain in the current state of motion due to its inertia Sleeve 14 rotates through so that locking of the propeller blades 6a, 6b is achieved.

In figure 7 1 is a schematic view of the folding propeller 10 according to the second embodiment in a position that lies between the folded position Z1 and the unfolded position Z2. figure 7 serves essentially to illustrate a transitional state of the unfolding process of the propeller blades 6a, 6b. From the representation of figure 7 it can be seen that, if the hub 2 is driven in reverse, the locking of the propeller blades 6a, 6b takes place via the bolt 18. The latter can take the propeller blades 6a, 6b with the help of the insertion bevels 20 before they are fully unfolded.

figure 8 shows a schematic view of the folding propeller 10 according to the second embodiment in an unfolded position Z2 and a propeller blade locking device 8 in an initial position Z10. From the figure in figure 8 It can be seen that the propeller blades 6a, 6b are each mounted via a bearing journal 12 which is arranged transversely to the axis of rotation A. In the figure 8 The representation shown corresponds to the case in which the folding propeller 10 is driven in the direction of rotation D, which corresponds to forward travel. Since in this direction of rotation D no advancing torque acts on the propeller blades 6a, 6b, locking the folding propeller 10 via the propeller blade locking device 8 is not absolutely necessary. Therefore can in this state, as in figure 5 shown, the propeller blade locking device 8 remain in the form of a sleeve 14 in an initial state Z10. Alternatively or additionally, the propeller blade locking device 8 can also be designed in such a way that the folding propeller 10 is also locked via the propeller blade locking device 8 in the direction of rotation D, which corresponds to forward travel.

In figure 9 a schematic side view of the folding propeller 10 according to the second embodiment is shown in an unfolded position Z2 and a propeller blade locking device 8 in a locking position Z20. In the figure 9 shown representation corresponds to, analogous to figure 6 , the case of reverse travel of the folding propeller 10. In this case, the folding propeller 10 is driven in the direction of rotation D, which corresponds to reverse travel. Since in this direction of rotation D an advancing torque acts on the propeller blades 6a, 6b, locking of the folding propeller 10 via the propeller blade locking device 8 is necessary or provided.

For this purpose, the propeller blade locking device 8 is designed in the form of a sleeve 14 such that a movement of the sleeve 14 into the locking position Z20 is forced by utilizing the mass inertia of the sleeve 14 that occurs when the hub 2 rotates. In this position, the propeller blades 6a, 6b are locked in the locking position Z20.

In figure 10 a schematic side view of a folding propeller 10 according to a third embodiment is shown in a first position Z110. The folding propeller 10 according to the third embodiment also includes a hub 2 which can be driven about an axis of rotation A via a drive shaft 4 . Furthermore, the third embodiment comprises two propeller blades 6a, 6b, which are arranged on the hub 2 so that they can pivot between a folded-in position Z1 (shown in phantom) and an unfolded position Z2. Furthermore, the third embodiment includes a propeller blade locking device 8 coupled to the hub 2, which is set up to lock the propeller blades 6a, 6b in the second, unfolded position Z2. For this purpose, the propeller blade locking device 8 includes a thread 22.

Consequently, the propeller blade locking device 8 according to the third embodiment is designed to be movable relative to the hub 2 in the direction of rotation D in such a way that by utilizing a mass inertia that occurs when the hub 2 rotates, a movement of the propeller blade locking device 8 from an initial position Z10 into a locking position Z20 ( not in figure 10 pictured) is enforced.

An attachment and a thread 22 are arranged on the drive shaft 4 . The hub 2 can be screwed onto the thread 22 . The special feature of the hub 2 is that due to the thread 22 the entire hub 2 can be screwed on and off the drive shaft 4 in the direction of the axis of rotation of the drive shaft 4 . This screw mechanism is actuated due to the inertia of the hub 2 and the drive shaft 4 .

By screwing and unscrewing the hub 2 relative to the drive shaft 4 in the first state according to figure 10 the propeller blades 6a, 6b are freely pivotable via bearing journals 12 transverse to the axis of rotation A. The propeller blades 6a, 6b are pivoted in a synchronized manner along their propeller blade roots via a toothed rack 24. in the in figure 10 In the first state shown, the propeller blades 6a, 6b can also be controlled via the toothed rack 24. The influencing of the propeller blades 6a, 6b is also initiated via a rod 26 which communicates with the rack 24.

This introduces an additional force to open the propeller blades, improving reliability and opening optimisation. This force, which is only effective in one direction, makes it possible, for example, to fold in the propeller blades 6a, 6b while driving forward.

The hub 2, the propeller blades 6a, 6b and the toothed rack 24 can be made of any material and can in particular have plastic or metal alloys.

On the other hand, the thread 22 must be made of a metal alloy in order to withstand the torques and to ensure sliding on the threaded surface. The thread 22 is preferably made of a material whose hardness differs from that of the hub 2 . This can prevent cold welding from occurring.

figure 11 shows a schematic side view of the folding propeller 10 according to the third embodiment of a second position Z220. According to the figure in figure 11 the propeller blades 6a, 6b are controlled via the rack 24 so that they are in the unfolded position Z2. In addition, the folding propeller 10 is in a locked position, the second position Z220, which is achieved in that due to the mass inertia of the drive shaft 4 and the hub 2, the two components are screwed onto one another.

figure 12 12 is a schematic perspective view of a folding propeller 10 according to a fourth embodiment in an unfolded position. According to the fourth embodiment, the folding propeller 10 comprises a hub 2, which has a first hub element 2a and a second hub element 2b, the hub 2 being about an axis of rotation A is drivable. The fourth embodiment further comprises two propeller blades 6a, 6b (6b not shown), which are arranged pivotably on the hub 2, and a propeller blade locking device coupled to the hub 2 in the form of a forced hub 28, which is set up to secure the propeller blades 6a, 6b, in to lock the unfolded position Z2.

The propeller blade locking device in the form of a forced hub 28 is designed to be movable relative to the hub 2, in particular the hub element 2b, in the direction of rotation D such that by utilizing a mass inertia that occurs when the hub 2 rotates, a movement of the propeller blade locking device in the form of a forced hub 28 is forced into a locking position Z20, in which the propeller blades 6a, 6b are locked.

In a further embodiment, instead of or in addition to the mass inertia, the backward driving torque can be used for locking.

Here, the two hub elements 2a and 2b can rotate freely within 90° to each other. This torsion is initiated and controlled by inertia. In the first hub element 2a there is a forced hub 28, which produces a stroke at the 90° rotation and thus drives a toothed rack 24 between the two propeller blades 6a, 6b and can thus control their end positions. Furthermore, the fourth embodiment has an indentation 30 on the constraining hub 28, which is located at the trailing end of the 90° twist and thus acts as an additional resistance against folding.

This introduces an additional force to open the propeller blades 6a, 6b, which is intended to improve reliability and optimization of the opening. This force is only effective in one direction and still allows folding when driving forward. The first hub element 2a, the constraining hub 28, the rack 24 and the propeller blades 6a, 6b have no material restrictions. These can include or consist of both plastic and metal alloys. The only limitation of the hub element 2b is that it should be heavier than the hub element 2a in order to achieve optimal results. The forced hub 28 and the rack 24 must be made of materials of different hardness to avoid cold welding.

As far as applicable, all individual features that are presented in the exemplary embodiments can be combined with one another and/or exchanged without departing from the scope of the invention.

Reference character list

A

axis of rotation

D

direction of rotation

SR

reverse thrust

Sv

forward thrust

Z1

folded position

Z2

unfolded position

Z10

starting position

Z20

locking position

Z110

First position

Z220

second position

2

hub

2a

First hub element

2 B

Second hub element

4

drive shaft

6a, 6b

propeller blades

8th

Propeller blade locking device

10

folding propeller

12

bearing journal

14

sleeve

16

recess

18

bars

20

lead-in bevel

22

thread

24

rack

26

pole

28

forced hub

30

deepening

Claims (15)

A folding propeller (10) comprising - a hub (2) which can be driven about an axis of rotation (A) via a drive shaft (4), - At least two propeller blades (6a, 6b) which are arranged pivotably on the hub (2) between a folded position (Z1) and an unfolded position (Z2), and - a propeller blade locking device (8) which is set up to lock the propeller blades (6a, 6b) in the unfolded position (Z2), characterized in that the propeller blade locking device (8) is movable relative to the hub (2) in the direction of rotation (D) between a starting position (Z10) and a locking position (Z20). Folding propeller (10) according to Claim 1, characterized in that the propeller blade locking device (8) is connected to the drive shaft (4) in a torsionally rigid manner, the hub (2) being decoupled from the propeller blade locking device (8) in the direction of rotation (D), with the Propeller blade locking device (8) has a sleeve (14). Folding propeller (10) according to Claim 2, characterized in that the hub (2) is designed to be movable in such a way that when a torque is applied to the drive shaft (4), the hub (2) moves from the starting position (Z10) into the locking position ( Z20) is enforced. Folding propeller (10) according to Claim 1, characterized in that the hub (2) is connected to the drive shaft (4) in a torsionally rigid manner, with the propeller blade locking device (8) being decoupled from the hub (2) in the direction of rotation (D), with the Propeller blade locking device (8) has a sleeve (14). Folding propeller (10) according to Claim 4, characterized in that the propeller blade locking device (8) is designed to be movable in such a way that, by utilizing a mass inertia that occurs when the hub (2) rotates, a movement of the propeller blade locking device (8) from a starting position ( Z10) is forced into a locking position (Z20) in which the propeller blades (6a, 6b) are locked. Folding propeller (10) according to Claim 4 or 5, characterized in that the propeller blade locking device (8) is designed to be movable in such a way that its mass inertia is specifically used to stop the movement of the propeller blade locking device (8) from the starting position (Z10) into the locking position (Z20 ) to force. Folding propeller according to one of the preceding claims, characterized in that the direction of rotation (D) corresponds to reverse rotation of the propeller blades (6a, 6b). Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blades (6a, 6b) are mounted on a bearing journal (12) arranged transversely to the axis of rotation (A). Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blade lock (8) is designed so that it is in the starting position (Z10) when the drive shaft (4) is at a standstill, in which case the propeller blades (6a, 6b ) can be pivoted freely between the folded position (Z1) and the unfolded position (Z2). Folding propeller (10) according to Claim 2 or Claim 5, characterized in that the sleeve (14) of the propeller blade locking device (8) has a recess (16) and a latch (18) in the area of each propeller blade (6a, 6b), the Latch (18) is preferably formed at a downstream end (20) of the sleeve (14). Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blade locking device (8) has an insertion bevel (20) which is designed such that in a state in which the propeller blade locking device (8) is not yet fully in the locking position ( Z20), folding in the propeller blades (6a, 6b) causes the propeller blade locking device (8) to be reset to its starting position (Z10). Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blade locking device (8) is made in one piece, preferably wherein the propeller blade locking device (8) and/or the propeller blades (6a, 6b) comprise a metallic material. Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blade locking device (8) is designed to lock the propeller blades (6a, 6b) in an unfolded position (Z2) while the folding propeller (10) is being towed, so that an autorotation the propeller blades (6a, 6b), the propeller blade arresting device (8) preferably being designed to enable an auto-rotation of the propeller blades (6a, 6b) for energy recovery from a speed of about 5 knots. Folding propeller (10) according to one of the preceding claims, characterized in that the propeller blades (6a, 6b) are designed in such a way that the initial opening of the propeller blades (6a, 6b) takes place using centrifugal force, preferably wherein the propeller blades (6a, 6b ) Have a metallic material, in particular a metal alloy. Drive for a boat with a folding propeller (10) according to one of Claims 1 to 14.

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