Patent Description:
Such a flow converter is known in the art and for example disclosed in <CIT>. Further flow converters of this kind are known from <CIT> and <CIT>.

These flow converters each define a flow channel into which the liquid flow is introduced so as to be flown, in a top view, against one half of the rotor so as to induce rotation of the rotor. The pivotable vanes of all these flow converters are passively self-aligning to the flow of liquid upon rotation of the rotor. In particular, the vanes located in the driven half of the rotor against which the liquid is flown pivot about the pivot axis being limited by abutment at a limit stop so that the liquid flow impacts on a large surface of the vanes resulting in rotation of the rotor. Upon further rotation of the rotor, the vanes being located in the non-driven half of the rotor should only provide for a little impact surface, because any impact of the liquid flow on these vanes would counteract the rotation. Hence, the vanes again pivot about the pivot axis so as to align the large surfaces with the liquid flow.

This aspect of the prior art improves efficiency of the flow converter but bears certain risks and disadvantages with respect to reliability, because the vanes repeatedly hit the limit stop with increased wear and, therefore, requiring short maintenance intervals involving higher maintenance costs.

To that extent, even further flow converters are known from <CIT> forming the basis for the preamble of claim <NUM> and <CIT>.

Accordingly, it is the object of the present invention to provide a device for generating electricity from a liquid flow as described in the introductory portion being more reliable enabling shorter maintenance intervals at lower costs.

This object is according to one aspect solved by the features defined in claim <NUM>. Embodiments of the invention are named in the dependent claims.

According to another aspect, this object is solved by actively pivoting the vanes about the pivot axes rather than passively as suggested in the prior art. This may preferably be achieved by a mechanical mechanism transmitting the rotation of the rotor to the vanes thereby pivoting the vanes about the pivot axes depending on the rotational position of the rotor. The mechanical mechanism may comprise a cam mechanism, a link mechanism or a combination thereof. Alternatively, one may force the vanes in one rotational direction by urging the vane about the pivot axis in one direction. This may be achieved by providing an elastic element, particularly a spring (for example a torsion spring or a tension spring).

According to an aspect, the device for generating electricity from a liquid flow comprises a rotor and a plurality of vanes. The rotor is preferably contained in housing and accommodated to be rotatable about an axis of rotation. The vanes are disposed in a radial and/or circumferential direction of the rotor and fixed to the rotor for common rotation with the rotor. Further, the vanes are each pivotable about a pivot axis parallel to the axis of rotation within a predetermined limited angular range. To limit the angular range, a limit stop is provided at which the vane abuts in one end position. If both positions are to be restricted, two limit stops may be provided at the opposite end positions of the angular range. Preferably each vane pivots (reciprocates) in opposite directions during rotation of the rotor, whereas the rotor rotates in only one direction. In order to have a balanced distribution of forces it is preferable that the pivot axes are equally spaced about a circumference of the rotor with the axis of rotation of rotor as a center. More, the device may preferably be configured to be completely immersed in the liquid during operation. In one embodiment, the axis of rotation of the rotor is vertically oriented during use. The housing may further comprise an inlet path for channeling the liquid flow relative to the axis of rotation and flow the liquid flow against one half (driven half) of the rotor whereas no liquid flow is flown against the opposite half (non-driven half) of the rotor relative to the axis of rotation. Thereby, the liquid flow is flown against the driven side of the rotor, that is that side of the rotor at which the direction of the liquid flow corresponds to the rotational direction of the rotor whereas a liquid flow opposite to the rotational direction of the rotor onto the vanes is prevented at the opposite side. Accordingly, the force applied by the liquid flow onto the vanes in the non-driven half counteracting the rotation is reduced and the resistance of the rotor is merely produced by the rotational movement of the vanes through the liquid, whereby the efficiency is improved. This effect may be dispensed if the vanes are pivotable about a pivot axis because even if the liquid flow is flown against the non-driven half, the surfaces of the vanes hit by the liquid flow are reduced if the vanes pivot so that there leading edge faces the liquid flow. Yet, it is preferred that both of the above features are combined to even further increase efficiency, because the latter also serves to reduce the resistance caused by the rotational movement of the vanes through the liquid.

To improve the above device in regard of reliability and to shorten the length of the maintenance interval, it is suggested to force the vanes into at least one rotational direction about the pivot axes, respectively. Thereby, the vanes are actively controlled preventing repeated high impacts on the vanes. Accordingly, wear of the vanes and, therefore, length of maintenance intervals and cost of maintenance may be reduced. In addition the movement of the vanes about the pivot axis being controlled is more reliable and independent from turbulences in the liquid flow. Also fluttering of the vanes may be prevented.

According to one embodiment, an actuator may be provided, which is driven upon or by the rotation of the rotor and configured to transmit the rotation of the rotor (driving force) to the vane, whereby the vane is forced to pivot about the pivot axis. Preferably, the actuator is configured to transmit the rotation of the rotor to the vane in both rotational directions of the vane. Accordingly, the vane may pivot about the pivot axis in opposite directions and depending on the rotational position of the rotor. Preferably, the actuator is a mechanism for physically or mechanically transmitting the rotation of the rotor to the vanes, thereby providing a simple and less cost intensive mechanism at the same time providing for ease of maintenance.

In order to provide for a balanced distribution of forces introduced into the vanes for rotation thereof about the pivot axes, it may be preferred to have two of said actuators, a first actuator at a first end of the vane in an axial direction parallel to the axis of rotation and a second actuator at a second end of the vane in an axial direction parallel to the axis of rotation opposite to the first end. Accordingly, the rotation of the vane about the pivot axis may be introduced at opposite ends with equal forces so that tilting of the vane may be prevented and, hence, larger tolerances may be used during production.

A very reliable mechanism requiring little maintenance is provided if the actuator comprises a cam follower moving along a cam surface upon rotation of the rotor. Thereby a mechanism similar to a camshaft can be used, which has been proven as very reliable. In this context, however, it is preferred that the camshaft is fixed to the housing, that is does not rotate together with voters. As a consequence, the cam followers move along the surface of the camshaft rather than vice versa. In that the distance of the cam follower to the axis of rotation is changed along the movement on the cam surface (by the cam surface), the vane may be forced to pivot about the pivot axis. According to an embodiment, the cam follower may be urged towards the cam surface by an elastic element, particularly a spring, even more particularly a torsion spring. Thereby, secure contact of the cam follower with the cam surface may be secured.

In order to ensure a secure guidance of the cam follower on the cam surface, it may be preferred to use a slotted guide as a cam surface. This also provides for a simple solution to enable rotational movement of the vane about the pivot axis in opposite directions as the cam follower may be forced away from the center axis by a cam surface located closer to the center axis (inner cam surface) and towards the center axis by a cam surface located further away from the center axis (outer cam surface). Alternatively to or in addition to the slotted guide, the cam follower or - if the cam follower is fixed to the vane - the vane itself may be urged by an elastic element into one direction relative to the rotational direction of the rotor to ensure contact of the cam follower with the cam surface and or to move the vane in opposite directions. For this purpose, an elastic element such as a tension spring or a torsion spring may be used.

In order to enable a smooth and reliable movement of the cam follower along the cam surface preferably with low friction, the cam follower may be a wheel rotatable about an axis parallel to the axis of rotation. The wheel runs along the cam surface rotating on the cam surface whereby low friction is obtained and a play between the cam follower and the cam surface may be reduced to a minimum. Further and if the wheel has an elastic running surface, play may even be avoided completely and a secure contact of the wheel against the cam surface be ensured.

According to one embodiment, the cam surface extends continuously about a circumference of the rotor with the distance between the cam surface and the axis of rotation changing along the circumference. As a result, continuous contact of the cam follower with the cam surface may be achieved preventing engagement and disengagement of the cam follower with the cam surface. Accordingly, reliability can be further enhanced.

The cam surface is preferably fixed. In other words, the rotor rotates relative to the cam surface or to put it differently the cam surface does not rotate together with the rotor. Hence, the cam follower which rotates together with the rotor as being for example part of the vane (the vanes rotate together with the rotor) moves along the cam surface so that even though the cam surface is fixed it has a function comparable to a common camshaft. In one embodiment, the cam surface may be fixed relative to the housing containing the rotor.

According to an embodiment the actuator acts as a lever arm wherein one end of the lever arm is connected to the vane and the opposite end is driven. If a driving force is applied to the opposite end, the lever arm rotates about the pivot axis of the vane, because of being connected at the opposite end to the vane, resulting in the pivoting movement of the vane. In this context, the actuator may be a lever arm or act as a lever arm. An example for the latter is a disk with its rotational center being preferably concentric with the pivot axis and the driving force being applied to the disc at an eccentric position. According to a preferred embodiment, the driving force is applied to the lever arm via the above-described cam follower. In other words, the cam surface acts on the cam follower upon rotation of the rotor and thereby drives the opposite end of the lever arm resulting in a pivoting movement of the vane.

Under certain conditions, it may be preferred that the speed of rotation of the rotor is converted to a higher or lower speed of the pivoting movement of the vanes. To obtain such a conversion with a simple construction, it may be preferred that each vane comprises a transmission comprising the above-described actuator, wherein the transmission provides for the transmission ratio.

According to one embodiment, the transmission comprises a first gear and a second gear. The first gear is mounted at one end of the vane in a direction parallel to the axis of rotation. The first gear is preferably disposed coaxial to the pivot axis. Also two first gears may be provided which are then provided at opposite ends of the vane to provide a balanced force distribution as described above. If two first gears are provided it is also preferred that two second gears are provided. The actuator described above is preferably the second gear. As a consequence, the second gear is driven by the rotation of the rotor and preferably has the cam follower being eccentrically disposed on the second gear. Upon rotation of the second gear, the first gear is rotated. One or more gears may be provided between the first and second gear. According to one embodiment however, the first gear and the second gear directly mesh. The first and second gears are preferably rotatable relative to the rotor. If the second gear has the cam follower, the cam follower moves along the cam surface and thereby rotates the second gear. This rotation is transferred is a directly or via other gears to the first gear, thereby rotating the vanes. As a result, a very simple transmission with low maintenance being required is achieved.

According to an aspect, the vanes are urged into one rotational direction by an elastic element. For example, a tension spring or a torsion spring may be used for this purpose. As previously described, the elastic element may alternatively or additionally be used to act on the vanes or the cam follower in order to secure a contact between the cam follower and the cam surface during rotation of the rotor.

Another problem concerning the application in running waters particularly rivers is that the flow rate of the liquid flow is under certain circumstances not sufficient to achieve an appropriate efficiency of the device. Further, the flow rate of the liquid in the river may not be constant and may necessitate adaption during operation.

In order to solve this problem it is suggested to provide a device for generating electricity comprising two or more (particularly an even number of rotors) and more particularly a device as described in <CIT> or as described above. The device is arranged between two floating bodies each having a curved airfoil surface facing the device, the airfoil surfaces forming a flow channel to be passed by the liquid flow.

In a particular embodiment, the rotor of the device is rotatable about a vertical axis meaning that the axis of rotation is substantially parallel to the surfaces of the airfoils facing towards the device. The two or more rotors are preferably arranged so that the axes of rotation of the rotors are parallel. In a particular embodiment, the rotor has a plurality of vanes equally spaced about the circumference of the rotor. Further, the device is preferably mounted so that the rotor of the device is completely immersed in the liquid.

Furthermore, it may be preferred that one or both surfaces of the airfoils facing towards the device are adjustable so as to change an angle of the surface relative to the flow direction of the liquid flow. For this purpose a control may be provided to enable adjustment during operation. Alternatively, the adjustment may be achieved by mechanical means at the site of the system by an installer of the system without adjustability during operation. The adjustability enables to adapt the inlet of the channel formed by the airfoils to the speed of the liquid flow to achieve the required flow rate of the liquid flow to achieve a high efficiency. In this context it has been found that an angle between <NUM>° and <NUM>°, preferably between <NUM>° and <NUM>° and most preferred <NUM>° of one surface of the airfoil relative to the flow direction of the liquid flow or the opposite air foil is advantageous to achieve an appropriate acceleration of the flow rate of the liquid flow. By the use of the above-described floating bodies with the airfoil an acceleration of twice the original speed of the running water can be obtained. This is particularly assisted in that under pressure is created at the outlet of the channel formed between the surfaces of the airfoils at the downstream position of the device whereby more liquid is sucked into the inlet formed between the surfaces of the airfoils at an upstream position of the device.

According to one embodiment, three floating bodies are provided wherein a first device for generating electricity from a liquid flow is disposed between an intermediate floating body and a first outer floating body and a second device for generating electricity from a liquid flow is disposed between the intermediate floating body and a second floating body opposite to the first floating body relative to the intermediate floating body, whereby a trimaran is formed.

It may also be advantageous if the floating bodies are movable relative to each other not only for adjustment of their inclination relative to each other as described above and to adjust to the intended liquid flow rate but also to close an inlet at an upstream side between the facing airfoil surfaces of the floating bodies to prevent damaging of the device/-s in case of for example floods in which the liquid flow rate of the running water is increased and a plurality of foreign matter may be expected to enter the inlet.

The later aspect described above may be implemented even independently from the pivotability of the vanes as described in claim <NUM>. According to an aspect, a device for generating electricity from a liquid flow is suggested comprising at least one rotor being rotatable about an axis of rotation and having a plurality of vanes spaced about the circumference of the rotor, and at least two floating bodies, wherein the rotor is rotatably fixed to the floating bodies so as to be (preferably completely) immersed in the liquid, the floating bodies each having an airfoil surface facing each other and the rotor, the airfoil surfaces forming a channel having an inlet at an upstream position of the rotor and an outlet at a downstream position of the rotor, whereby the liquid flow rate (speed) of the liquid passing the rotor may be adjusted.

According to an embodiment, the floating bodies are adjustable relative to each other with respect to the inclination of the airfoil surface/-s relative to the flow direction of the liquid flow and/or to each other. Thereby, one and the same system can be used for different applications with the ability to adjust to the circumstances. Even further, it may be conceivable to construct the floating bodies so as to be movable relative to each other between an operating position and a non-operating position, wherein the inlet formed between the facing airfoils surfaces is closed in the non-operating position. This aspect is also described in more detail in the particular embodiment below.

Further features, embodiments and advantages of the invention are described in the following detailed description referring to the accompanying drawings.

In the following description, the same or similar parts throughout the different embodiments are referred to by the same reference numerals and a repeated description of these elements is omitted.

<FIG> shows a cross sectional view of a flow converter according to a first embodiment. The flow converter comprises two rotors <NUM> and has a symmetric configuration in <FIG> with a longitudinal line of symmetry <NUM>.

The rotor <NUM> is rotatable about an axis of rotation <NUM>. The axis of rotation <NUM> in the present embodiment is oriented perpendicular to the liquid flow indicated by the arrow <NUM>. In a particular embodiment, the flow converter is completely immersed in liquid, for example a river with the axis of rotation <NUM> being vertically oriented.

The rotor <NUM> further comprises a bottom plate <NUM> and a top plate <NUM> (see <FIG>). A plurality of vanes <NUM> are fixed to the rotor <NUM> between the top plate <NUM> and the bottom plate <NUM>. Each of the vanes <NUM> is fixed to the plates <NUM>, <NUM> so as to be pivotable about a pivot axis <NUM> in a limited angular range. The vanes <NUM> are equally spaced about the circumference of the rotor and equally distanced in the circumferential direction as is visible from the <FIG>. The pivoting movement of the vanes <NUM> will be described in more detail below.

The rotors <NUM> are provided in a housing <NUM> and rotatable relative thereto. The housing <NUM> has an inlet path <NUM> for channeling the liquid flowing in the direction <NUM> into the flow converter, particularly the inlet path <NUM>. The construction of the housing <NUM> is selected so that the liquid channeled by the inlet path <NUM> is flown against only one half, namely the driven half of the rotor <NUM>. As best visible from <FIG> the driven half of the lower rotor <NUM> is the lower half and the driven half of the upper rotor is the upper half. The driven and non-driven halves are respectively separated by the dotted line <NUM> in <FIG> further indicates (see arrows R) that the two rotors rotate in opposite directions. In particular, the upper rotor <NUM> rotates counterclockwise and the lower rotor <NUM> rotates clockwise.

It is also apparent from <FIG> that the vanes <NUM> are oriented in the driven half with their opposite faces <NUM>, extending from a leading edge to a trailing edge, facing the liquid flow <NUM> and being as perpendicular thereto as possible so that the liquid is flown against these faces <NUM> thereby driving the rotor <NUM> in the rotational direction R. To the contrary the faces <NUM> in the non-driven half of the rotor <NUM> are oriented with their faces <NUM> substantially aligned with the flow direction of the liquid so that the liquid is not flown as much against the faces <NUM> as in the driven half of the rotor <NUM> thereby reducing both the resistance of the vanes <NUM> rotating through the liquid and reducing the impact of the liquid flown against the vanes in the non-driven half preventing a force tending to counter rotate the rotor.

In order to force the vane <NUM> in one rotational direction about the pivot axis <NUM>, in the present embodiment even a both directions, a cam mechanism is implemented.

The cam mechanism comprises a slotted guide <NUM> disposed in a plate <NUM> fixed relative to the housing <NUM>. Accordingly, the plate <NUM> does not rotate together with the rotor <NUM>, but the rotor <NUM> rotates relative to the plate <NUM> and hence the slotted guide <NUM>. The depicted embodiment comprises a plate <NUM> with a slotted guide <NUM> at both ends of the rotor in the axial direction. The configuration of the plates <NUM> at both ends is identical as is the remainder of the cam mechanism so that the cam mechanism will only be described at one end. The slotted guide <NUM> has a cam surface <NUM> (inner cam surface) continuously extending about the circumference of the rotor <NUM> with the axis of rotation <NUM> as a center. The cam surface <NUM> has a changing distance to the axis of rotation <NUM> along the circumference. A further cam surface <NUM> (outer cam surface) is provided which runs parallel to the cam surface <NUM>. Hence, what has been said with respect to the cam surface <NUM> also applies to the cam surface <NUM>.

Each vane <NUM> comprises at opposite ends an actuator formed as a lever arm <NUM>. One end of the lever arm <NUM> is fixed to the vanes <NUM>. The opposite end of the lever arm <NUM> has a cam follower <NUM>. The cam follower <NUM> comprises a rotatable wheel <NUM> and an axis <NUM> attached to the lever arm <NUM>. The wheel <NUM> has an elastic surface. The diameter of the wheel <NUM> is adapted to the width of the slotted guide <NUM> with or without play so that the wheel <NUM> is engaged between the inner cam surface <NUM> and the outer cam surface <NUM>.

In order to allow the vanes <NUM> to rotate about the pivot axis <NUM> without the cam follower <NUM> and particularly the axis <NUM> interfering with the top and bottom plate <NUM>, <NUM> curved slots <NUM> are formed in the plates <NUM>, <NUM> corresponding to each vane <NUM> with the pivot axis <NUM> as a center of the curve.

In operation, the rotor <NUM> together with the vanes <NUM> rotates. Thereby, the wheels <NUM> of the cam follower <NUM> run along the cam surfaces <NUM>, <NUM> within the slotted guide <NUM>. Because the distance of the cam surfaces <NUM> and <NUM> changes relative to the axis of rotation <NUM> along the circumference, the cam followers <NUM> are either pushed away or towards the axis of rotation. Accordingly, the vanes <NUM> are forced to rotate about the pivot axis <NUM> in the one or the other direction depending on the movement of the cam follower <NUM>. The axis <NUM> of the cam follower <NUM> thereby may enter into the curved slots <NUM> to allow the pivoting movement. The above-described system is purely mechanical with simple parts so that no electronic control or electric motor is required. Still it is enabled that the vanes <NUM> pivot about the pivot axis <NUM> depending on the rotational position of the rotor so as to achieve the effect described above with respect to the orientation of the vanes <NUM> in the driven and non-driven half of the rotor <NUM>.

An alternative second embodiment achieving a similar effect is shown in <FIG>. This embodiment implements a transmission mechanism <NUM>, which may be disposed at opposite ends or at one end only. The benefit of this embodiment as compared to the previous embodiment is on the one hand, that the curved slots <NUM> in the top and bottom plates <NUM>, <NUM> may be avoided and that a transmission ratio between the speed of rotation of the rotor <NUM> about the axis of rotation <NUM> and the speed of rotation of the vanes <NUM> about the pivot axis <NUM> may be achieved.

As the remainder of the second embodiment is similar to the first embodiment, a repeated description of the parts which are referred to by the same numerals is avoided.

The transmission mechanism <NUM> comprises first gears <NUM> fixed to the vanes <NUM> concentric to the pivot axis <NUM> so that rotation of the first gears <NUM> results in a rotation of the vanes <NUM> about the pivot axis <NUM>, respectively. The gears <NUM> are rotatably fixed to the top plate <NUM> of the rotor <NUM>. Moreover, second gears <NUM> are disposed meshing with the first gears <NUM> and rotatably fixed to the top plate <NUM> about an axis of rotation <NUM> parallel to the axis of rotation <NUM> and the pivot axis <NUM>. Each of the second gears <NUM> has a cam follower <NUM> disposed concentric to the axis of rotation <NUM> but rotating together with the second gear <NUM>. The cam followers <NUM> are constructed similar as the cam followers <NUM> shown in <FIG> each having an axis <NUM> and a wheel <NUM>.

A support <NUM> is fixed relative to the housing <NUM>. The support <NUM> comprises a slotted guide <NUM> with an inner cam surface <NUM> and an outer cam surface <NUM> similar as in the first embodiment described above. In particular, the distance between the inner cam surface <NUM> and the parallel outer cam surface <NUM> to the axis of rotation <NUM> changes along the circumference. Thereby the cam followers <NUM> or more particularly their wheels <NUM> are pushed toward or away from the axis of rotation <NUM>.

During operation, the rotor <NUM> rotates relative to the support <NUM> and hence the slotted guide <NUM>. Thereby, the wheels <NUM> of the cam followers <NUM> move along the circumference of the slotted guide <NUM> and run along the cam surfaces <NUM> and <NUM> as in the first embodiment. Because of the changing distance, and as previously mentioned, the wheels <NUM> and hence the cam follower <NUM> are pushed away and towards the axis of rotation <NUM> whereby the second gears <NUM> are rotated. Because the second gears <NUM> mesh with the first gears <NUM>, the rotation of the second gears <NUM> is transferred to the first gears <NUM>. Because the first gears <NUM> are connected to the pivot axis <NUM> of the vanes <NUM>, the vanes <NUM> are rotated by the rotation of the first gears <NUM> to assume the corresponding rotational position about the pivot axis <NUM> depending on the rotational position of the rotor as described in the first embodiment above. Depending on the size of the first and second gears <NUM> and <NUM> the rotational speed of the vanes <NUM> about the pivot axis <NUM> may be adjusted as needed. In addition, weakening of the top and bottom plates <NUM> and <NUM> because of the curved slots <NUM> in the first embodiment may be avoided by this construction.

A third embodiment, which does not form part of the present invention and may be implemented isolated from or combined with the first and second embodiment described above, is shown in <FIG>. The rotor shown in <FIG> has a plurality of vanes <NUM> having protrusions <NUM> at opposite ends engaging with a curved cutout <NUM>, the curve having the pivot axis <NUM> as a center. Opposite ends <NUM> of the cutout <NUM> serve as a limit stop to limit the angular range in which the vanes <NUM> may pivot, Baron the protrusion <NUM> abut at the ends <NUM> of the cutout <NUM> in the corresponding end positions of the angular range. According to this embodiment, a tension spring <NUM> is provided preferably at opposite ends of the vanes <NUM> in the axial direction. The tension springs <NUM> are fixed at one end <NUM> to the top or bottom plate <NUM>, <NUM> respectively and at the opposite end <NUM> to the vanes <NUM> at a distance to the pivot axis <NUM>. Thereby, the tension springs <NUM> force (urge) the vanes <NUM> into one rotational direction about the pivot axis <NUM> (in the present embodiment in a clockwise direction). This is the most simple construction of actively controlling the movement of the vanes <NUM>, though it is only possible to control this movement in one rotational direction. Further, the springs may also be used to urge the vanes <NUM> in one direction and ensure secure engagement of the cam followers with the cam surface in other embodiments. Of course different solutions to urge the cam followers <NUM> against the cam surface may be used instead of these springs. In this context a torsion spring may be used applying a torsion force to the vanes <NUM> at the pivot axis <NUM>. Also in the first and/or second gears <NUM> may be urged by a torsion spring to urge the cam followers <NUM> into contact with the inner cam surface <NUM>.

In view of the aforesaid, it is clear that the basic idea of the present invention may be implemented differently than described above and that combinations of the embodiments are conceivable unless they contradict each other.

One application is for example shown in <FIG> and <FIG>. <FIG> embodies two of the devices described earlier wherein the housings <NUM> are visible in <FIG> and <FIG>. Hence, the system disclosed in these drawings comprises four rotors <NUM> which may have the configuration as described above, but which may also have a different construction with for example fixed vanes or vanes which are passively pivoting about the pivot axis. The construction of the rotor is not of significance with respect to this particular application and this particular application may also be embodied with different rotors <NUM>.

In order to immerse the devices comprising the rotors <NUM> in a river <NUM>, three floating bodies <NUM>, <NUM> and <NUM> are provided. The floating body <NUM> is an intermediate floating body which fixed to the waterside <NUM> using a crossbar <NUM>. An axis <NUM> at the end of the crossbar <NUM> opposite to the connection to the waterside <NUM> is fixed to the ground of the river by a support <NUM>. The intermediate floating body <NUM> is rotatably supported by the axis of <NUM> so as to automatically adjust to the flow direction <NUM> of the liquid flow in the river <NUM>.

As will be best visible from <FIG>, the longitudinal section of the floating bodies resembles an airfoil with airfoil surfaces <NUM> of the outer floating bodies <NUM>, <NUM> facing airfoil surfaces <NUM> of the intermediate floating body <NUM>. The facing surfaces <NUM> and <NUM> form a flow channel <NUM> having an inlet <NUM> upstream of the rotors <NUM> and an outlet <NUM> downstream of the rotors <NUM>.

The outer floating bodies <NUM>, <NUM> are respectively fixed to the intermediate floating body <NUM> by arms <NUM> and <NUM> which are at opposite ends rotatably fixed to the outer floating bodies <NUM> and <NUM> and to the intermediate floating body <NUM>. Thereby, parallelograms are formed which by movement of the arms <NUM>, <NUM> enable to adjust the inclination alpha of the airfoil surfaces <NUM> relative to the flow direction <NUM> and/or the airfoil surfaces <NUM> to adjust to the requirements of the river <NUM> particularly the flow rate of the liquid flow in the direction <NUM>.

Accordingly, it is enabled by moving the arms <NUM> to change the inlet <NUM> and the flow channel <NUM> so as to create an underpressure depicted by the dark areas in <FIG> at the outlet <NUM> thereby suctioning the liquid into the inlet <NUM> with a higher flow rate (speed/velocity) depicted by the light grey areas in <FIG> near the inlet <NUM> than the flow rate of the river <NUM>. As a result, the efficiency of the devices for generating electricity may be enhanced.

In addition, the arms <NUM> may rotate so as to bring the outer floating bodies <NUM>, <NUM> in front of the intermediate floating body <NUM> thereby closing the inlet <NUM>, thus bringing the entire system into a non-operating position. In this position, the rotors <NUM> are protected from any liquid flowing through the rotors <NUM> so that for example during floods the rotors may be protected from being damaged by too high flow rates of the liquid flowing in the river <NUM> or from foreign matters being entrained in the river during those instances.

Claim 1:
Device for generating electricity from a liquid flow, comprising:
a rotor (<NUM>) rotatable about an axis of rotation (<NUM>);
a plurality of vanes (<NUM>) extending parallel to the axis of rotation (<NUM>) and fixed to the rotor for common rotation with the rotor, each vane (<NUM>) being pivotable about a pivot axis (<NUM>) parallel to the axis of rotation (<NUM>) within a predetermined limited angular range, wherein a limit stop (<NUM>) is provided at which the vane (<NUM>) abuts in one end position, the pivot axes (<NUM>) being equally spaced about a circumference of the rotor with the axis of rotation (<NUM>) as a center,
wherein the vanes (<NUM>) are forced into at least one rotational direction about the pivot axes (<NUM>), respectively, and
the vanes (<NUM>) each comprise an actuator driven upon rotation of the rotor (<NUM>) and configured to transmit the rotation of the rotor (<NUM>) to the vane (<NUM>), whereby the vane (<NUM>) is forced to pivot about the pivot axis (<NUM>),
characterized in that
the actuator has a cam follower (<NUM>) moving along a cam surface (<NUM>, <NUM>) upon rotation of the rotor (<NUM>), wherein the distance of the cam surface (<NUM>, <NUM>) to the axis of rotation (<NUM>) changes along the movement of the cam follower (<NUM>) along the cam surface (<NUM>, <NUM>) to force the vane (<NUM>) to pivot about the pivot axis (<NUM>).