GB2589708A

GB2589708A - Rotor assembly

Info

Publication number: GB2589708A
Application number: GB2014052.1A
Authority: GB
Inventors: John Bradley Albert
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-09-05
Filing date: 2020-09-07
Publication date: 2021-06-09
Also published as: GB202014052D0; GB201912814D0

Abstract

A rotor assembly (5, fig.1) has a rotatable carrier (10, fig.1) on which two or more vanes 54 are rotatably mounted with axes 52 parallel to that of the carrier, whose axis 24 is perpendicular to the air current or wind 13, as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in an opposite rotational sense, the frontal area of the vanes is reduced, that is feathered reducing drag, over that part of the vanes orbit during which the vane travels generally against the airflow minimising the profile to reduce wind resistance, the assembly determines the wind direction and adjusts the carrier so that the vane orientation is optimised relative to and/or in response to wind direction. Preferably the assembly uses planetary 32, or epicyclic, gears arranged around a fixed central gear 20 and has a wind direction sensor, and encoders for the vanes, allowing a motor to be used to drive the assembly – with gears, chains (162, fig.3) or pulleys – so that it can be reorientated to the prevailing air current. The assembly can be housed in a duct and further mounted to a vehicle (fig.4).

Description

ROTOR ASSEMBLY

Field of the Invention

The present invention relates to a rotor assembly that uses vanes to create torque around an axis to produce power to drive a generator or other consumer unit.

Background of the Invention

Wind turbines fall into two main categories; lift-based and drag-based. Lift-based turbine examples include conventional horizontal axis aerofoil wind turbines. The most common drag-based wind turbine is a Savonius rotor wherein the rotational motion is caused by a drag differential between the two faces of the turbine vanes. Unlike conventional aerofoil wind turbines, the airflow direction is generally transverse to the axis of rotation of a Savonius rotor. These types of turbines comprise vanes around a central axis, the vanes having a curved cross section, so that the concave face has relatively higher drag, and the convex face has relatively lower drag. When an airflow is applied transverse the axis of rotation, this drag differential causes rotation of the of the turbine around the axis. These simple turbines are inefficient at producing power as the vanes move in an unconfined airflow. Additionally, the torque produced by these designs of turbines is small when compared with other designs of wind turbine.

An object of this invention is to provide a more efficient rotor assembly.

Summary of the Invention

An aspect of the present invention provides a rotor assembly comprising: a carrier mounted and rotatable about a central axis; two or more vanes rotatably mounted on the carrier, each vane being rotatable about a respective vane axis parallel to and spaced from the central axis and interconnected with the carrier such that as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in a rotational sense opposite that in which the carrier is caused to rotate by airflow over the vanes, such that the frontal area of the vanes is reduced over that part of the vanes orbit during which the vane travels generally against the airflow, in which the assembly comprises means for determining wind direction and means for positioning the assembly relative to and/or in response to wind direction.

An aspect of the present invention provides a rotor assembly comprising: a carrier mounted and rotatable about a central axis; two or more vanes rotatably mounted on the carrier, each vane being rotatable about a respective vane axis parallel to and spaced from the central axis and interconnected with the carrier such that as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in a rotational sense opposite that in which the carrier is caused to rotate by airflow over the vanes, such that the frontal area of the vanes is reduced over that part of the vane's orbit during which the vane travels generally against the airflow, in which the assembly comprises means for turning the carrier to position the vanes such that the frontal area of the vanes is maximised over that part of the vane's orbit during which the vane travels generally with the airflow.

The assembly may comprise means for determining wind direction and means for positioning the assembly relative to and/or in response to wind direction.

In some aspects and embodiments the positioning means turns the carrier to position the vanes such that the frontal area of the vanes is maximised over that part of the vane's orbit during which the vane travels generally with the airflow.

A positioning gear may be mounted to the carrier to turn the rotor so as to position it into the airflow.

Some embodiments comprise a sensor, for example an encoder, for determining and/or monitoring prevailing wind direction In some embodiments a motor is provided for positioning the carrier/vanes relative to/based on wind direction.

Wind direction may be monitored, for example, regularly (e.g. at regular intervals/periodically) or substantially continuously. Changes to the orientation of the assembly may be made in response. In some embodiments, therefore, wind conditions are measured and the assembly is set up for those conditions. In other embodiments dynamic changes can be made in response to changes in wind conditions.

Changes to the position of the assembly may be made to position the vanes into the wind to ensure correct phasing of the vanes.

Some embodiments comprise a wind direction sensor and a motor; the sensor output may control the motor.

A motor may drive rotation of the assembly such that the rotor assembly can be positioned relative to the wind direction.

The carrier may be or may comprise a turntable.

Some embodiments consist of two vanes.

A gear arrangement may be provided.

A fixed gear may be mounted on a rotor shaft.

A positioning gear may be fixedly mounted to a rotor shaft A chain or other such suitable means may transfer the rotation of a motor to the positioning gear and through the rotor shaft such that the rotor can be positioned accordingly.

The positioning gear may be used to position the vanes into the wind to ensure correct phasing of the vanes.

Gears may turn in a direction rotationally opposite to that of an adjacent meshing gear.

Each vane may be mounted on a respective drive shaft.

The assembly may have a stationary gear fixedly mounted against rotation about the central axis, around which the carrier rotates.

A drive gear may be mounted to rotate with each drive shaft.

An epicyclic gear train may be provided, for example comprising inner and outer planetary gears; the planetary gears may interconnect a stationary gear and a drive gear of each vane.

A belt drive may connect a fixed gear and a drive gear of each vane.

A positioning gear may be mounted to the carrier and driven by the motor to turn the rotor so as to position it into the airflow.

Diametrically opposite vanes may be orthogonal to one another when the vane is at a minimum frontal area when travelling against the airflow.

In some embodiments the assembly may be housed within a duct to confine and direct the airflow to turn through an angle such to reduce the variation in the frontal area as the vanes move from a point in their orbit in which they move with the airflow towards a point moving against the airflow.

The present invention also provides a wind turbine including a rotor assembly as described herein.

The present invention also provides a vehicle-mounted/mountable wind turbine having a rotor assembly as described herein.

According a further aspect of the present invention, there is provided a rotor assembly comprising: a carrier mounted and rotatable about a central axis; two or more vanes rotatably mounted on the carrier, each vane being rotatable about a respective vane axis parallel to and spaced from the central axis and interconnected with the carrier such that as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in a rotational sense opposite that in which the carrier is caused to rotate by airflow over the vanes, such that the frontal area of the vanes is reduced over that part of the vanes orbit during which the vane travels generally against the airflow; in which the rotor assembly additionally comprises a sensor for determining wind direction, and a motor for positioning the rotor assembly such that the rotor assembly can be positioned relative to the wind direction.

The sensor may be an encoder and may control the motor such that the motor drives rotation of the assembly such that the assembly can be positioned relative to the wind direction.

Each vane may be mounted on a respective drive shaft.

The rotor assembly may have a stationary gear fixedly mounted against rotation about the central axis, around which the carrier rotates.

A drive gear may be mounted to rotate with each drive shaft.

The rotor assembly may have an epicyclic gear train, comprising inner and outer planetary gears, which interconnects the stationary gear and the drive gear of each vane.

A belt drive may connect the fixed gear and the drive gear of each vane.

A positioning gear may be mounted to the carrier to turn the rotor so as to position it into the airflow before rotation of the rotor is initiated Diametrically opposite vanes may be orthogonal to on another when the vane is at a minimum frontal area when travelling against the airflow.

The rotor assembly may be included in a wind turbine.

The rotor assembly may be included in a vehicle-mounted wind turbine.

The duct may be shaped so as to divert the airflow through a step in the duct, such that the inlet airflow and outlet airflow are substantially parallel.

The rotor assembly may be arranged such that the axis of rotation is horizontal or vertical.

The rotor vanes may have flat or curved surfaces. They may also have a continuous surface, or a surface comprising perforations or protrusions.

A further aspect provides a rotor assembly comprising: a carrier mounted and rotatable about a central axis; two or more vanes rotatably mounted on the carrier, each vane being rotatable about a respective vane axis parallel to and spaced from the central axis and interconnected with the carrier such that as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in a rotational sense opposite that in which the carrier is caused to rotate by airflow over the vanes, such that the frontal area of the vanes is reduced over that part of the vanes orbit during which the vane travels generally against the airflow, in which the rotor assembly is housed within a duct to confine and direct the airflow to turn through an angle such to reduce the variation in the frontal area as the vanes move from a point in their orbit in which they move with the airflow towards a point moving against the airflow.

In some embodiments the duct outlet airflow is not parallel to the duct inlet airflow.

Different aspects and embodiments may be used separately or together.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with the features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

Brief Description of the Drawings

Embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure I is a cross-section of an embodiment of the rotor assembly.

Figure 2 is the rotor assembly of Figure I with the rotor blades in a different rotational position. Figure 3 is a perspective view of the gear arrangement of the rotor assembly of Figures I and 2. Figure 4 is a schematic illustration of a turbine mounted on a vehicle.

Figures SA, 5B and SC illustrate a part of the rotor assembly having a vertical axis of rotation, in three different positions in one revolution of the rotor.

Description

The exemplary embodiments are described in sufficient detail to enable those of ordinary skill in the art to embody and implement the systems and processes herein described. It is important to understand that embodiments can be provided in many alternative forms and should not be construed as limited to the examples set forth herein.

Accordingly, while embodiments can be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the drawings and described in detail below as examples.

There is no intent to limit to the particular forms disclosed. On the contrary, all modifications, equivalents, and alternatives falling within the scope of the appended claims should be included.

In the following description, all orientational terms, such as upper, lower, radially and axially, are used in relation to the drawings and should not be interpreted as limiting on the invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein are to be interpreted as is customary in the art. It will be further understood that terms in common usage should also be interpreted as is customary in the relevant art and not in an idealised or overly formal sense unless expressly so defined herein.

Referring now to the drawings, wherein like reference numbers are used to designate like elements throughout the various views, several embodiments of the present invention are further described. The figures are not necessarily drawn to scale, and in some instances the drawings may have been exaggerated or simplified for illustrative purposes only. One of ordinary skill in the art will appreciate the many possible applications and variations of the present invention based on the following examples of possible embodiments of the present invention.

An embodiment of the invention is shown in Figure I. A cross section of a turbine I is shown, having a rotor assembly 5 housed within a duct 16, the duct having an inlet 12 and an outlet 14. The duct 16 has a curved wall 18 to divert the input airflow 13 through an angle. The rotor assembly 5 comprises a carrier 10 which is fixedly mounted on a rotor shaft 22, both of which are rotatable around a central axis 24. The rotor shaft 22 passes through the fixed gear 20 which remains stationary while the rotor shaft 22 and the carrier 10 turn. Two drive gears 50a, 50b are rotatably mounted to the carrier 10 by respective drive shafts 52a, 52b. Vanes 54a, 54b are mounted on and fixed to respective drive shafts 52a, 5213. Vane 52a is shown in the maximum upstream position within the duct, and vane 526 is shown in the maximum downstream position within the duct. The drive shafts 52a, 52b rotate around axes parallel to and spaced from the axis of the rotor shaft 22. Intermediate gears 30a, 306 are rotatable mounted on the carrier 10, each gear 30a, 30b being rotatable about a respective axis I 32a, I 32b parallel to and spaced from that of the axis of the rotor shaft 22. The intermediate gears 30a, 30b connect the drive gears 50a, 50b to the fixed gear 20. The gear ratio of the fixed gear to the drive gears 50a, 50b is 2:1 so that the vanes 54a, 54b only rotate 180° for every 360° rotation of the carrier. In this embodiment, the drive gears 50a, 50b have 40 teeth, and the intermediate gears 30a, 3013 and the fixed gear have 20 teeth each. The drive gears 50a, 50b and the intermediate gears 30a, 306 form a double planetary gear system around a sun gear, the fixed gear 20.

Figure 2 shows the turbine I of Figure I after the rotor assembly 5 has rotated by 90 degrees around the rotor shaft 22. Vanes 52c and 52d are at intermediate points between the maximum upstream and maximum downstream positions.

The pressure applied to the vanes 54a and 54b by the inlet airflow 13 causes the carrier 10 to rotate around the central rotor axis. The vanes 54a, 54b cannot freely rotate with the airflow due to the engagement of the drive gears 50a, 50b, with the fixed gear 20 via the belt drives 40a, 40b. The rotation of the carrier 10 relative to the fixed gear 20 therefore causes rotation of the drive gears 50a, 50b. The gear ratio of the fixed gear 20 to drive gears 50a, 50b is 2:1 so that the vanes 54a, 546 only turn through 180° for every 360° rotation of the carrier 10. This vane rotation causes the vane at the intermediate point 52d travelling against the airflow to be substantially parallel to the inlet airflow 13. This gives the vane a feathered effect, reducing the drag on the vane when it is travelling against the direction of the inlet airflow 13. The vane at the intermediate point 52c travelling with the airflow is therefore held substantially perpendicular to the inlet airflow 13. As the vanes rotate with the carrier around the central axis 24, each vane is turned such that its angular position stays substantially transverse the airflow path throughout the length of the curved duct wall 18. The inlet airflow 13 is not parallel to the outlet airflow 15 due to the shape of the curved duct wall 18 (although further ducting may be provided to achieve this). The combination of the wall 18 and the angular position of the vane therefore allows a greater frontal area to face the airflow through the duct 16.

The duct confines and directs the airflow to turn through an angle such to reduce the variation in the frontal area as the vanes move from a point in their orbit in which they move with the airflow towards a point moving against the airflow. The duct outlet airflow may not be parallel to the duct inlet airflow.

Figure 3 shows a gear arrangement on the reverse of a carrier I 10, external to the duct. The fixed I 5 gear 120 is mounted on the rotor shaft 122, and a positioning gear 160 being fixedly mounted to the rotor shaft 122. A chain 162 transfers the rotation of a motor 164 to the positioning gear 160 and through the rotor shaft 122 such that the rotor can be positioned accordingly before allowing the turbine to rotate. This is used to position the vanes into the wind to ensure correct phasing of the vanes. The arrows on the gears and rotor shaft show the direction of rotation each gear turning in a direction rotationally opposite to that of its adjacent meshing gear.

Figure 4 shows an embodiment of the invention mounted on a vehicle 202. The turbine 201 can be mounted on the top of a vehicle 202 such that the airflow over the top of the vehicle causes the turbine 201 to rotate. The airflow into the turbine is indicated by arrows A, and the airflow out of the turbine is indicated by arrows B. The vane 254a is shown in the intermediate point travelling against the airflow and is therefore substantially parallel to the airflow direction, or 'feathered' to reduce drag. The vane 254b is shown in the intermediate point travelling with the airflow and has a large frontal area and is therefore the driven vane at this point in time of its rotation.

The duct may also be provided so that the inlet and outlet airflow are parallel, but the duct is stepped, so the airflow is still diverted through an angle within the duct.

Figures SA, 5B & SC shows an alternative embodiment wherein the axis of rotation is vertical and the rotor assembly is not housed in a duct. The airflow indicated by arrows C still remains transverse the axis of rotation. The direction of rotation around the drive shaft 352 is indicated by arrows D. Figure SA is when the vane 354a is at the maximum upstream position and the vane 354b is at the maximum downstream position. Figure 5B shows vane 354b at the intermediate point travelling against the airflow and therefore angled to give a minimum frontal area. Hidden from view, the vane 354a will be at an intermediate point travelling with the wind and will be angled to give a maximum frontal area. Figure SC shows the vanes 354a and 354b between the two positions shown by Figure SA and Figure SB. In this embodiment, the vanes are not within a duct so as to show the rotation of the vanes 354a, 354b relative to the rotation of the rotor shaft 352.

The rotor assembly comprises a motor to drive the positioning gear such that its position is optimised in relation to the wind direction. A sensor is provided to detect the wind direction and output signals to the motor so that the turbine can be rotated into the wind. The sensor may be an encoder on the top of the rotor assembly. The motor rotates the fixed gear and therefore the carrier such that the vanes can be positioned with the vane travelling with the airflow at 900 to the airflow, and the vane travelling against the airflow parallel to it such that the drag of that vane is minimised. A control system may be used to connect the sensor and the motor and can be programmed such that it will prohibit the carrier being rotated.

This rotational control allows for the turbine to be rotated with changing wind directions to improve turbine efficiency.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims

CLAIMSI. A rotor assembly comprising: a carrier mounted and rotatable about a central axis; two or more vanes rotatably mounted on the carrier, each vane being rotatable about a respective vane axis parallel to and spaced from the central axis and interconnected with the carrier such that as the carrier is caused to rotate by the effect of an airflow over the vanes, the vanes are caused to rotate about their respective axes in a rotational sense opposite that in which the carrier is caused to rotate by airflow over the vanes, such that the frontal area of the vanes is reduced over that part of the vanes orbit during which the vane travels generally against the airflow, in which the assembly comprises means for determining wind direction and means for positioning the assembly relative to and/or in response to wind direction.
2. An assembly as claimed in claim I, comprising a sensor for determining and/or monitoring prevailing wind direction.
3. An assembly as claimed in claim I or claim 2, comprising an encoder.
4. An assembly as claimed in any preceding claim, a motor for positioning the carrier relative to the wind direction.
5. An assembly as claimed in any preceding claim, in which wind direction is monitoring regularly or continuously and changes to the orientation of the assembly are made in response.
6. An assembly as claimed in any preceding claim, in which changes to the position of the assembly are made to position the vanes into the wind to ensure correct phasing of the vanes.
7. A rotor assembly as claimed in any preceding claim, comprising a wind direction sensor and a motor, in which the sensor output controls the motor.
8. A rotor assembly as claimed in any preceding claim, in which a motor drives rotation of the assembly such that the rotor assembly can be positioned relative to the wind direction.
9. An assembly as claimed in any preceding claim, in which the carrier is a turntable.
10. An assembly as claimed in any preceding claim, in which a gear arrangement is provided.
I I. An assembly as claimed in claim 10, in which a fixed gear is mounted on a rotor shaft.
12. An assembly as claimed in claim 10 or claim II, in which a positioning gear is fixedly mounted to a rotor shaft.
13. An assembly as claimed in claim 12, in which a chain transfers the rotation of a motor to the positioning gear and through the rotor shaft such that the rotor can be positioned accordingly.
14. An assembly as claimed in claim 13, in which the positioning gear is used to position the vanes into the wind to ensure correct phasing of the vanes.
15. An assembly as claimed in any of claims 10 to 14, in which each gear turning in a direction rotationally opposite to that of an adjacent meshing gear.
16. A rotor assembly as claimed in any preceding claim, in which each vane is mounted on a respective drive shaft.
17. A rotor assembly as claimed in any preceding claim, having a stationary gear fixedly mounted against rotation about the central axis, around which the carrier rotates.
18. A rotor assembly as claimed in any of claims 10 to 17, in which a drive gear is mounted to rotate with each drive shaft.
19. A rotor assembly as claimed in claim 18, in which an epicyclic gear train comprising inner and outer planetary gears which interconnect the stationary gear and the drive gear of each vane.
20. A rotor assembly as claimed in claim 19, in which a belt drive connects the fixed gear and the drive gear of each vane.
21. A rotor assembly as claimed in any preceding claim, in which a positioning gear is mounted to the carrier and driven by the motor to turn the rotor so as to position it into the airflow.
22. A rotor assembly as claimed in any preceding claim, in which diametrically opposite vanes are orthogonal to one another when the vane is at a minimum frontal area when travelling against the airflow.
23. An assembly as claimed in any preceding claim, the assembly being housed within a duct to confine and direct the airflow to turn through an angle such to reduce the variation in the frontal area as the vanes move from a point in their orbit in which they move with the airflow towards a point moving against the airflow.
24. A wind turbine including a rotor assembly as claimed in any preceding claim.
25. A vehicle-mounted wind turbine having a rotor assembly as claimed in any of claims 1 to 23.