Variable toroidal propeller

Abstract

A variable toroidal propeller (10) is proposed, comprising a hub (12) and toroidal propeller blades (14) connected to the hub (12). The hub (12) is configured to operably couple the blades (14) to an actuator (44), and the blades (14) are configured to deform when the actuator (44) is operated.

Description

Technical Field

[0001] The proposed technology generally relates to the field of propellers for aviation and marine applications, and more particularly to variable and toroidal propellers.

Background Art

[0002] Toroidal propellers have blades that form a loop. These can be used for both aviation and marine applications, such as for example, unmanned aircraft and motorboats. Toroidal propellers have the advantage of being considerably quieter than conventional propellers. Toroidal propellers are also known to generate fewer vortices and be more efficient. A variable propeller, or variable pitch propeller, can typically change the orientation of the blades relative to the hub by rotating the blades around an axis transverse to the propeller centerline. This allows for the selection of a more effective pitch at a given speed. The proposed technology aims to combine the advantages of toroidal propellers and variable propellers.

Summary of the Invention

[0003] In a first aspect of the proposed technology, a variable toroidal propeller or variable pitch toroidal propeller is proposed, the propeller comprising a hub or boss and toroidal propeller blades connected to the hub. The hub or propeller is configured to operably couple the blades to an actuator, and the blades are configured to deform, or change their shape, or change the pitch of the propeller when the actuator is actuated.

[0004] In a second aspect of the proposed technology, an assembly is proposed comprising a variable toroidal propeller or a variable pitch toroidal propeller and an actuator. The propeller comprises a hub or boss and toroidal propeller blades connected to the hub. The actuator is operably coupled to the blades, for example by the hub, and is configured to deform the blades, change the shape of the blades, or change the pitch of the propeller when the actuator is actuated. In other words, the assembly comprises a variable toroidal propeller according to a first aspect of the proposed technology and an actuator, the actuator being operably coupled to the blades, for example by the hub, and configured to deform the blades, change the shape of the blades, or change the pitch of the propeller when the actuator is actuated.

[0005] It is understood that the propeller may have additional toroidal blades connected to a hub, and that actuators may be operably coupled to the additional blades and configured to deform the additional blades. For example, the propeller may have a total of two, three, or four toroidal blades. Each blade may be configured with any of the features described below, or a combination thereof. It is further understood that the hub may be configured to be connected to the propeller shaft.

[0006] In this specification, deformation is understood as a transformation of an object from a reference shape to its current shape, where the shape is a set of shapes that include the positions of all particles of the object. Deformation includes structural deformation, such as elastic deformation. Deformation also includes mechanical deformation, for example, by mechanical joints or paired pairs having one or more degrees of freedom. Deformation is understood to include a combination of structural and mechanical deformation.

[0007] The blade may have a blade tip and may consist of a first blade portion and a second blade portion connected at the blade tip, or may have both, and the blade may include a first blade root and a second blade root, the first blade root connecting the first blade portion to the hub, and the second blade root connecting the second blade portion to the hub. The blade is configured to deform the first blade portion or change its pitch when the actuator is operated. In other words, the actuator is configured to deform the first blade portion or change its pitch. The blade may be further configured to deform the second blade portion or change its pitch when the actuator is operated, i.e., the actuator may be further configured to deform the second blade portion or change its pitch.

[0008] It is understood that the first blade section, the tip section, and the second blade section are configured to define at least a portion of the loop. The first blade root and the second blade root may be separated at the hub or spaced apart. In this case, the blade and the hub may together form a loop. The first blade root and the second blade root may be spaced apart at least parallel to the propeller centerline or along the propeller centerline. This means that when viewed from the side, the blade outlines the loop. This contributes to increasing the rigidity of the blade in the direction parallel to the propeller centerline, and furthermore, allows the use of thinner blades that are more easily deformed. This is advantageous, for example, in watercraft applications. The first blade root and the second blade root may be spaced apart at least tangentially to the propeller centerline. This allows the use of a shorter hub, which is advantageous in aerospace applications.

[0009] The propeller centerline, or propeller axis of rotation, is understood as a straight reference line or axis that passes through the hub and around which the propeller rotates during use. Typically, the propeller centerline lies at the center of the propeller axis or is coaxial with the propeller axis. The blade tip is understood as the maximum reach of the propeller blade from the propeller centerline.

[0010] The leading edge is understood as the edge of the propeller blade that first enters the fluid or flow when providing forward thrust. The trailing edge is understood as the edge of the propeller blade that separates from the fluid or flow when providing forward thrust. When the propeller is viewed from the rear, the leading edge is the furthest and the trailing edge is the closest. The chord is understood herein as part of a helical curve centered on the propeller centerline and connecting the leading and trailing edges. The chord length is understood as the length of the chord at a given radial position.

[0011] The forward-moving blade is understood as the pressure side of the propeller blade. Typically, the forward-moving blade is visible when viewing the propeller from the rear. The backward-moving blade is understood as the negative-pressure side of the propeller blade. Typically, the backward-moving blade is not visible when viewing the propeller from the rear.

[0012] The pitch of a propeller is generally understood as the straight-line distance traveled when the propeller makes one rotation in a fluid with no or minimal slippage. Similarly, the pitch of a blade or blade section is generally understood as the straight-line distance traveled when the propeller makes one rotation in a fluid with no or minimal slippage. The blade section is the cross-section cut out by a cylinder centered on the propeller's centerline. The pitch reference line is the line passing through the leading and trailing edges of the blade section. The pitch angle is the angle between the pitch reference line and a line perpendicular to the propeller's centerline. The pitch angle of a constant-pitch blade is the same from the root to the tip. In other words, blades generally have a blade section with the same pitch angle. A variable-pitch blade has a pitch angle that changes from the root to the tip. In other words, blades generally have cross-sections with different pitch angles.

[0013] The blade may be configured to work in cooperation with an actuator to change the shape or curvature of the forward-moving surface of the first and / or second blade portion. In other words, the actuator may be configured to change the shape or curvature of the forward-moving surface in the blade cross-section of the first and / or second blade portion. This change may be in the blade cross-section. For example, the blade cross-section may be at the blade root, the blade tip, or between the blade root and the blade tip. It is understood that the shape of the backward-moving surface may change along with the shape of the forward-moving surface. Deformation at the blade tip is advantageous because it can change the pitch of the first and second blade portions.

[0014] The blades may be configured to cooperate with the actuator to change the pitch of the first and / or second blade sections when the actuator is activated. In other words, the actuator may be configured to change the pitch of the first and / or second blade sections. The actuator may be configured to change the pitch angle of the blade cross-section of the first and / or second blade sections. For example, the blade cross-section may be at the blade root, the blade tip, or somewhere between the blade root and the blade tip.

[0015] The actuator described above may be a hydraulic actuator or an electromechanical actuator. An actuator is understood as a device that performs mechanical work by converting energy to deform, for example, the blades described above, or to change their shape. This work is understood to be performed when the actuator is in operation. It is further understood that the actuator must be coupled with a control device and an energy source in order to function. For example, the control device may consist of a set of valves, and the energy source may be a hydraulic source such as a pump. The control device may be a set of electrical switches, the energy source may be a battery, or the control device may be a set of manual levers.

[0016] The above states that the propeller is configured to operably connect its blades to an actuator, or that the actuator is operably connected to the blades. The propeller may include a mechanical connection or mechanical component configured to operably connect its blades to an actuator, or to operably connect its blades to an actuator. In other words, the propeller may include a mechanical connection configured to transmit the work performed by the actuator to the blades. For example, the first hub, the second hub, the first blade holder, and the second blade holder described below may each form part of a mechanical connection.

[0017] The actuator may be located inside the hub, or primarily located inside the hub. This means that the entire actuator is located inside the hub, or a large portion of the actuator is located inside the hub. For example, the actuator may comprise a hydraulic cylinder and a piston, and the hub may form the cylinder. In other words, the actuator may be inside the hub, or the actuator may form part of the propeller. The actuator may be located outside the hub, or primarily located outside the hub. This means that the entire actuator is located outside the hub, or a large portion of the actuator is located outside the hub. For example, the actuator may be an electromechanical actuator located outside the hub.

[0018] The hub may be a rigid structure, meaning it is composed of parts that cannot move relative to each other. In other words, the positions where the wings connect to the hub may be fixed relative to each other.

[0019] The hub may comprise a first hub portion and a second hub portion, the first and second hub portions being structurally separate or distinct and having an adjustable relative orientation and / or position. The first blade root is connected to the first hub portion, and the second blade root is connected to the second hub portion, and the first and second hub portions may be configured to be operably coupled to an actuator and to change the relative orientation and / or position of the first and second hub portions when the actuator is operated, or the actuator may be configured to change the relative orientation and / or position of the first and second hub portions. This allows for deformation of the blades even when the first and second blade roots are fixed to the hub. A change in the relative orientation or position between the first hub and the second hub causes a change in the relative orientation or position between the first blade root and the second blade root, which in turn deforms the blade, for example, causing a change in pitch.

[0020] The change in the relative orientation of the first hub portion and the second hub portion may be a rotation about the propeller centerline. The change in the relative position of the first hub portion and the second hub portion may be along the propeller centerline or parallel to the propeller centerline. For example, the hub may have a cam coupling between the first hub portion and the second hub portion, or a cam coupling may be formed, configured to change the relative orientation of the first hub portion and the second hub portion by rotation about the propeller centerline when the relative position of the first hub portion and the second hub portion changes along the propeller centerline. In this case, the actuator may be configured to change the relative position of the first hub portion and the second hub portion along the propeller centerline.

[0021] The hub or propeller may include a first blade retainer or first blade mounting section that connects the root of a first blade to the hub or a first hub section. Similarly, the hub or propeller may include a second blade retainer or second blade mounting section that connects the root of a second blade to the hub or a second hub section. The blade retainer is understood to be fixed to the blade root.

[0022] The first blade root or the first blade fastener can be fixed to the hub or the first hub portion, or fixed to the hub or the first hub portion. Similarly, the second blade root or the second blade fastener can be fixed to the hub or the second hub portion, or fixed to the hub or the second hub portion. This means that the orientation or position of the blade root cannot be changed with respect to the hub to which the blade root is connected, or to the hub portion.

[0023] The features and functions relating to the first wing section are described above. The same features and functions can also be embodied in, or in relation to, the second wing section. The orientation and / or position of the first blade root or the first blade retainer relative to the hub or the first hub portion can be variable or adjustable. For example, the first blade retainer may be configured to rotate relative to the hub or the first hub portion, the first blade root may be configured to tilt relative to the hub or the first hub portion, and / or the first blade root may be configured to move relative to the hub or the first hub portion. In other words, the first blade retainer can form an articulated joint with respect to the hub or with respect to the propeller centerline.

[0024] The first blade fixture and the actuator may be separated. This means that the first blade fixture does not directly contact the actuator. The hub or first hub portion can interconnect the first blade fixture and the actuator. In other words, the hub or first hub portion can connect the actuator to the first blade fixture. As described above, the actuator may be configured to change the relative orientation and / or position of the first hub portion and the second hub portion. When the first blade fixture and the actuator are separated, the orientation and / or position of the first blade root or the first blade fixture may be configured to change relative to the first hub portion when the relative orientation and / or position of the first hub portion and the second hub portion is changed. In other words, the first blade root or the first blade fixture may be configured to passively change its orientation and / or position relative to the hub or the first hub portion when the actuator is operated.

[0025] The first blade root or first blade retainer may be operably connected to an actuator and configured to change or alter its orientation and / or position relative to the hub, the first hub portion, or the propeller centerline when the actuator is operated. In other words, the actuator may be operably connected to the first blade root or first blade retainer and configured to change or alter the orientation and / or position of the first blade root or first blade retainer relative to the hub, the first hub portion, or the propeller centerline.

[0026] The first blade root or the first blade fixture may be configured to rotate relative to the hub or the first hub portion when the actuator operates. In other words, the actuator may be configured to rotate the first blade root or the first blade fixture relative to the hub or the first hub portion, or to rotate the first blade root or the first blade fixture around the first blade axis. The first blade axis may intersect the propeller centerline or may be perpendicular to the propeller centerline. It is understood that the first blade axis can intersect the propeller centerline.

[0027] The first blade root or the first blade fixture may be configured to tilt relative to the hub or the first hub portion when the actuator operates. In other words, the actuator may be configured to tilt the first blade root or the first blade fixture relative to the hub or the first hub portion, or relative to the propeller centerline. This tilt may be lateral relative to the hub or the first hub portion, or tangential relative to the propeller centerline. Alternatively, or in addition to this, this tilt may be longitudinal relative to the hub or the first hub portion, or may vary the tilt of the blade relative to the propeller centerline. The actuator may be configured to combine two or more of the above-mentioned changes in orientation. For example, it may be configured to combine rotation and tilt.

[0028] The first blade root or the first blade retainer may be configured to move relative to the hub or the first hub portion when the actuator is operated. In other words, the actuator may be configured to move the position of the first blade root or the first blade retainer relative to the hub or the first hub portion. This movement may be outward or inward relative to the hub or the first hub portion, or radial relative to the propeller centerline. This movement may be longitudinal relative to the hub or the first hub portion, or parallel to the propeller centerline. This movement may be lateral relative to the hub or the first hub portion, or tangential relative to the propeller centerline. The actuator may be configured to combine two or more of the above position changes. For example, it may be configured to combine lateral and longitudinal movement relative to the hub or the first hub portion. The actuator may be configured to combine one or more of the above orientation changes with one or more of the above position changes. For example, it may be configured to combine a rotational change with a longitudinal change.

[0029] As described above, the hub may have a first hub portion and a second hub portion that are structurally separate and adjustable relative to each other. It is understood that this can be combined with the various changes in orientation and position described herein. For example, the actuator may be configured to rotate the first hub portion relative to the second hub portion, to move the first hub portion relative to the second hub portion, and to rotate the first vane fixture relative to the first hub portion.

[0030] The propeller or blade may be configured to move the position of the first blade root or the first blade fixture relative to the second blade root or the second blade fixture when the actuator is actuated. In other words, the actuator may be configured to move the position of the first blade root or the first blade fixture relative to the second blade root or the second blade fixture. This movement may be outward or inward with respect to the hub or the first hub portion, or may be radial with respect to the propeller centerline. This movement may be along the hub or the first hub portion, or may be parallel to the propeller centerline. This movement may be lateral with respect to the hub or the first hub portion, or may be tangential with respect to the propeller centerline. For example, this can be achieved by fixing the second blade root or the second blade fixture to the hub, or by configuring the actuator to perform only the first movement for the position of the first blade root or the first blade fixture and only a second movement different from the first movement for the position of the second blade root or the second blade fixture. It is understood that the relative position changes described herein may be combined with either the above-described change in the orientation and / or position of the first blade root, or the relative orientation and / or position change between the first hub portion and the second hub portion.

[0031] It is understood that the blade or actuator may be configured to change the orientation and / or position of the second blade root or the second blade fixture in the same manner as described above with respect to the first blade root or the first blade fixture.

[0032] The blade can have an average chord length, and the chord length may vary by less than 40%, less than 25%, or less than 10% from the average between the first blade root and the second blade root. Such chord lengths have been found to be suitable for water applications.

[0033] A feather may have a maximum chord length, and the chord length at the feather tip may be less than 40%, less than 20%, or less than 10% of the maximum chord length. In other words, the feather may taper towards the feather tip. The first feather portion may have a maximum chord length, and the chord length at the feather tip may be less than 40%, less than 20%, or less than 10% of the maximum chord length. In other words, the first feather portion may taper towards the feather tip. Similarly, the second feather portion may have a maximum chord length, and the chord length at the feather tip may be less than 40%, less than 20%, or less than 10% of the maximum chord length. In other words, the second feather portion may taper towards the feather tip.

[0034] The blades may have a maximum chord length, and the chord length at the hub may be less than 75%, less than 50%, or less than 25% of the maximum chord length. In other words, the blades may taper towards the hub. The first blade section may have a maximum blade chord length, and the chord length at the root of the first blade may be less than 75%, less than 50%, or less than 25% of the maximum blade chord length. In other words, the first blade section may taper towards the hub or towards the root of the first blade. Similarly, the second blade section may have a maximum blade chord length, and the chord length at the root of the second blade may be less than 75%, less than 50%, or less than 25% of the maximum blade chord length. In other words, the second blade section may taper towards the hub or towards the root of the second blade. Tapering towards the blade tip and root has been shown to be suitable for aerospace applications. The tapering towards the blade tip contributes to increasing the blade's flexibility during deformation such as rotation relative to the hub at the base of the first blade, while maintaining structural strength along the propeller's centerline.

[0035] The blade may have a first side and a second side joined at the leading and trailing edges, the first side may form a forward-moving surface on the first blade portion of the propeller and a backward-moving surface on the second blade portion. Similarly, the second side may form a backward-moving surface on the first blade portion of the propeller and a forward-moving surface on the second blade portion. This means that the blade has a twisted appearance.

[0036] The blades may have a maximum axial extension length parallel to the propeller centerline and a maximum radial extension length radially relative to the propeller centerline. The maximum axial extension may be greater than 60%, greater than 80%, or greater than 100% of the maximum radial extension. In other words, there may be an axial gap between the leading edge of the first blade root and the trailing edge of the second blade root, and there may be a radial gap between the hub and the blade tip, with the axial gap being greater than 60%, greater than 80%, or greater than 100% of the radial gap. The axial gap is understood to be parallel to the propeller centerline, and the radial gap is understood to be perpendicular to the propeller centerline. This contributes to increased structural strength along the propeller centerline, and furthermore, allows for thinner blades that are more easily deformed. For example, this is advantageous in watersport applications, especially high-speed watersport applications.

[0037] The maximum axial extension may be less than 40%, less than 20%, or less than 10% of the maximum radial extension. This is advantageous in aerospace applications. This means that the blade has a bent appearance when, as described above, the first side forms a forward-moving blade surface on the first blade portion of the propeller and a backward-moving blade surface on the second blade portion of the propeller.

[0038] Various extension lengths can change during blade deformation, and these relationships are understood to exist with any changes in the orientation and / or position of the first and second blade roots, or the first and second blade fixtures. In other words, the actuator may be configured to vary the maximum axial and maximum radial extensions of the blades. The blades can be deformed during use. For example, the blade tips can be bent forward during use. The specified relative extension lengths are understood to be defined relative to a stationary propeller.

[0039] The feather may be a single, unjointed structure, meaning that the feather itself does not allow relative movement between its different parts without deformation. In other words, the first and second feather sections may form a single continuous structure. In this case, the deformation of the feather described above is elastic deformation.

[0040] Alternatively, the feather may be an articulated structure, meaning that the feather itself allows relative movement between its different parts without deformation. The feather may comprise a first feather segment, a second feather segment, and an articulated joint, where the first and second feather segments are juxtaposed and interconnected by the articulated joint. The articulated joint may be a hinge joint, a rotary joint, a universal joint, or a spherical joint. This allows the first and second feather segments to move relative to each other without deformation of themselves. It is understood that the first and second feather segments may form at least part or all of the feather. For example, the first or second feather portion may be divided into a first feather segment and a second feather segment, or the first feather portion may constitute the first feather segment, and the second feather portion may constitute the second feather segment. The latter means that the articulated joint is located at the tip of the blade. This articulated structure contributes to increasing the degree of freedom to obtain the desired deformation. It is understood that the blade may have additional blade segments and joints configured as described above.

[0041] The blades may be made of fiber-reinforced polymer or fiber-reinforced plastic, or may be made primarily of them. For example, the entire blade may be made of fiber-reinforced polymer, or more than 50% by volume of the blade may be made of fiber-reinforced polymer. Preferably, the polymer is a cured thermosetting resin. Preferably, the fibers are carbon fibers. The carbon fibers may be in the form of woven sheets of carbon fibers. The sheets may overlap to form a layered structure. This allows the blade thickness to be varied both between the leading edge and the trailing edge, and between the first blade root and the second blade root. The sheets may be arranged along the aforementioned first and / or second sides. This is advantageous in combination with the increased axial stiffness of the blade, as described above, when, for example, the first and second blade roots are spaced parallel to the propeller centerline. Arranging the sheet along the side of the blade contributes to improving the flexibility of the blade perpendicular to the side without significantly affecting the axial rigidity of the blade itself. The fact that the blade is made of a fiber-reinforced polymer is advantageous, as it allows the aforementioned first and second blade fixtures to be configured to distribute the load to the first and second blade roots when the actuator is operating. For example, the first and second blade fixtures may be made of metal such as stainless steel. The fiber-reinforced polymer can have a Young's modulus of 200 to 500 Gpa.

[0042] The blade may have, or may be equipped with, a protective shield positioned to protect the blade from cavitation. The shield may be made of a metal such as stainless steel. This is advantageous when combined with a blade primarily composed of a fiber-reinforced polymer, which may have a lower tolerance to cavitation than metal. The shield may be positioned on the trailing surface of the blade. This contributes to protecting the blade from cavitation on the negative pressure surface. In addition to, or instead of, the shield may be positioned on the leading edge of the blade. This contributes to protecting the blade from vortex cavitation at the tip. The shield may be a sheet-like structure. The shield may partially define the first side and / or second side. The shield may partially cover the fiber-reinforced polymer. Thus, the shield has little impact on the structural strength and deformability of the blade.

[0043] Instead of the feather being composed of a fiber-reinforced polymer, the feather may be composed of a metal such as stainless steel, or may be primarily composed of one. For example, the entire feather may be composed of metal, or more than 50% of the feather may be composed of metal. This is advantageous when combined with the fact that the feather has an articulated structure, as described above. The metal may have a Young's modulus of at least 100 GPa, preferably between 150 GPa and 215 GPa. In one example, the metal is stainless steel having a Young's modulus of 190-200 GPa, such as 193 GPa.

[0044] Alternatively, the feathers may be made of polymer, meaning the entire feather is made from this material. This is advantageous for low-load aerospace applications. The above and other features and advantages of the proposed technology will be better understood from the following detailed description of preferred embodiments of the proposed technology, in conjunction with the attached drawings. [Brief explanation of the drawing]

[0045] [Figure 1]This is a perspective view of a variable toroidal propeller for high-speed watercraft applications. [Figure 2] This is a perspective view of a variable toroidal propeller for aviation applications. [Figure 3] This is a perspective view of another variable toroidal propeller for high-speed watercraft applications. [Figure 4] A perspective view of another variable toroidal propeller for aviation applications. [Figure 5] Figure 1 is a schematic cross-sectional view of the assembly of the propeller and the internal hydraulic actuator. [Figure 6] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 7] Figure 3 is a schematic cross-sectional view of the assembly of the propeller and the internal hydraulic actuator. [Figure 8] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 9] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 10] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 11] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 12] This is a schematic cross-sectional view of another assembly consisting of a variable toroidal propeller and an internal hydraulic actuator. [Figure 13] Figure 2 is a schematic cross-sectional view of the assembly of the propeller and the external electromechanical actuator. [Figure 14] Figure 4 is a schematic cross-sectional view of the assembly of the propeller and the external electromechanical actuator. [Figure 15] This is a perspective view of the blades and hub of a variable toroidal propeller. [Figure 16] This is a perspective view of the blades and hub of another variable toroidal propeller. [Figure 17] A perspective view of another variable toroidal propeller. [Figure 18] This is a perspective view of the blades and hub of another variable toroidal propeller. [Modes for carrying out the invention]

[0046] Figure 1 is a perspective view of a variable toroidal propeller 10 for high-speed watercraft applications. The propeller 10 has a hub 12 and three toroidal blades 14 connected to the hub 12. Various connections between the blades 14 and the hub 12 are described below in reference to Figure 5. The hub 12 is centered on the propeller centerline 16, and the blades 14 are arranged symmetrically with respect to the propeller centerline 16. The blades 14 are structurally and functionally identical.

[0047] Each blade 14 consists of a first blade portion 18 and a second blade portion 20 connected at the blade tip 22 of the blade 14. The blade has a first blade root 24 that connects the first blade portion 18 to the hub 12, and a second blade root 26 that connects the second blade portion 20 to the hub 12. The first blade root 24 and the second blade root 26 are arranged at a distance from the hub 12, mainly parallel to the propeller centerline 16. In this way, the blades 14 and the hub 12 together form a loop.

[0048] The chord length along the blade 14 varies by less than 10% from the average chord length of the blade 14. The blade 14 has a maximum axial extension length parallel to the propeller centerline 16 and a maximum radial extension length radially relative to the propeller centerline 16, the former being approximately 110% of the latter. The blade 14 has a leading edge 32 and a trailing edge 34. The blade 14 also has a first side surface 36 and a second side surface 38 joined at the leading edge 32 and the trailing edge 34. The first side surface 36 forms the blade forward surface 40 of the first blade portion 18 and the blade backward surface 42 of the second blade portion 20, and the second side surface 38 forms the blade backward surface 42 of the first blade portion 18 and the blade forward surface 40 of the second blade portion 20.

[0049] The hub 12 has a structurally separate first hub portion 28 and a second hub portion 30 that can be adjusted relative to each other. The first blade root 24 is connected to the first hub portion 28, and the second blade root 26 is connected to the second hub portion 30. The hub 12 has a projection 62 for attaching the propeller 10 to a propeller shaft (not shown). The hub 12 has a first blade fixing device 46 for fixing the first blade root 24 to the first hub portion 28, and a second blade fixing device 48 for fixing the second blade root 26 to the second hub portion 30.

[0050] The blade 10 is a non-articulated, one-piece structure composed of a carbon fiber reinforced polymer. The polymer is a cured thermosetting resin, and the carbon fibers are in the form of woven sheets that overlap to form a layered structure. These sheets are arranged along the first side 36 and the second side 38 of the blade 14.

[0051] As shown in Figure 5, the propeller 10, together with the actuator 44, forms an assembly 8. The actuator 44 is located inside the hub 12 and can therefore be considered part of the propeller 10. The first hub portion 28 is connected to the second hub portion 30 by a linear coupling 50 positioned along the propeller centerline 16. The first hub portion 28 interconnects the first blade fixture 46 with the actuator 44, and the second hub portion 30 interconnects the second blade fixture 48 with the actuator 44. The actuator 44 is configured to move the first hub portion 28 along the propeller centerline 16 relative to the second hub portion 30, and further to move the position of the first blade root 24 along the propeller centerline 16 relative to the second blade root 26. The first hub portion 28 and the second hub 30 constitute a mechanical connection portion 60 configured to transmit the work performed by the actuator 44 to the blades 14. Thus, the actuator 44 is operably coupled to the blade 14 and configured to deform the blade 14.

[0052] As shown in Figure 5, the actuator 44 is an internal hydraulic actuator having a cylinder 52 formed by a first hub portion 28 and a double-acting piston 54 fixed to a second hub portion 30 by a piston rod 56. A hydraulic conduit 58 extends from the outside of the propeller 10 through the piston rod 56 to the outlets on both sides of the piston 54. Thus, the actuator 44 is configured to change the position of the first hub portion 28 relative to the second hub 30 by adjusting the pressure of the hydraulic fluid in the hydraulic conduit 58 using an external hydraulic control system.

[0053] Figure 2 is a perspective view of a variable toroidal propeller 10 for aviation applications. This propeller 10 differs from the propeller 10 described in relation to Figure 1 in that it has two blades 14, the first blade root 24 and the second blade root 26 of each blade 14 are spaced apart at the hub 12, mainly tangentially with respect to the propeller centerline 16, to form a loop. The chord length along the blades 14 varies by less than 10% from the average chord length of the blades 14. The blades 14 have a maximum axial extension length parallel to the propeller centerline 16 and a maximum radial extension length radially with respect to the propeller centerline 16, the former being about 15% of the latter. The hub 12 does not have dedicated blade fasteners. Instead, the first blade root 24 is welded to the first hub section 28, and the second blade root 26 is welded to the second hub section 30. As shown in Figure 13, the propeller 10, together with the actuator 44, forms an assembly 8. The actuator 44 is located outside the hub 12 and is not considered part of the propeller 10. As in the embodiment of Figure 1, the first hub section 28 is connected to the second hub section by a linear coupling 50 positioned along the propeller centerline 16.

[0054] The actuator 44 is an electromechanical rotary actuator, and the propeller 10 has a mechanical connection 60 that operably connects the actuator 44 to the blades 14. The mechanical connection 60 consists of an arm 64 that connects the rotating shaft 66 of the actuator 44 to the outer ring of a bearing 68. The inner ring of the bearing 68 is fixed to a second hub 30. The mechanical connection 60 further consists of a propeller shaft 70 fixed to a first hub 28, and the first hub 28 is rotationally locked to the second hub 30 by a linear coupling 50. When in use, the propeller shaft is connected to an electric motor (not shown) fixed to the actuator 44. Therefore, when the actuator 44 is activated, the second hub 30 is moved to a position parallel to the propeller centerline 16 relative to the first hub 28. In this way, the actuator 44 is operably connected to the blades 14 and configured to deform the blades 14.

[0055] Figure 3 is a perspective view of another variable toroidal propeller 10 for high-speed water surface applications. The propeller 10 forms part of the assembly 8 shown in Figure 7. The propeller 10 differs from the propeller 10 described in relation to Figure 1 in that the hub 12 is a single rigid structure and the points where the blades 14 connect to the hub 12 are fixed relative to each other. In addition, each of the first blade fixtures 46 and the second blade fixtures 48 is connected to the rest of the hub 12 by a rotary coupling 72. The first blade fixture 46 can rotate around the first blade axis 74, and the second blade fixture 48 can rotate around the second blade axis 76. Both the first blade axis 74 and the second blade axis 76 are perpendicular to the propeller centerline 16 and intersect the propeller centerline 16.

[0056] The actuator 44 has a cylinder 52 formed by the hub 12 and a double-acting piston 54, the piston rod 56 being movable relative to the entire hub 12. The propeller 10 has a mechanical connection 60 in the form of a yoke 78 fixed to the piston rod 56 and cooperating pins 80 fixed to a first blade fixture 46 and a second blade fixture 48. The pins 80 are eccentric with respect to the first blade axis 74 and the second blade axis 76. The yoke 78 is configured to cam the pins 80 when the actuator 44 is operated, thereby rotating the first blade fixture 46 and the second blade fixture 48. The first blade root 24 and the second blade root 26 are fixed to the first blade fixture 46 and the second blade fixture 48, respectively. In this way, the actuator 44 is operably coupled to the blade 14 and configured to deform the blade 14.

[0057] Figure 4 is a perspective view of another variable toroidal propeller 10 for aviation applications. The propeller constitutes part of the assembly 8 shown in Figure 14. Propeller 10 differs from propeller 10 described in relation to Figure 2 in that the hub 12 is a single rigid structure and the points where the blades 10 connect to the hub 12 are fixed relative to each other. In addition, the first blade fixture 46 can rotate around the first blade axis 74 and the second blade fixture (not shown) can rotate around the second blade axis 76. Both the first blade axis 74 and the second blade axis (not shown) are perpendicular to the propeller centerline 16.

[0058] The actuator 44 is an electromechanical rotary actuator, and the propeller 10 has a mechanical connection 60 that operably connects the actuator 44 to the blades 14. The mechanical connection 60 consists of an arm 64 that connects the rotating shaft 66 of the actuator 44 to the outer ring of a bearing 68. The inner ring of the bearing 68 is fixed to a hollow rod 82 that extends into the hub 12. A yoke 78 is fixed to the hollow rod 82, and a cooperating pin 80 is fixed to a first blade fixture 46 and a second blade fixture (not shown). The pin 80 is eccentric with respect to the first blade axis 74 and the second blade axis (not shown). The mechanical connection 60 further consists of a propeller shaft 70 that passes through the hollow rod 82 and is fixed to the hub 12. When in use, the propeller shaft is connected to an electric motor (not shown) fixed to the actuator 44. Next, when the actuator is activated, the first blade holder 46 and the second blade holder (not shown) rotate around the first blade axis 74 and the second blade axis (not shown). The first blade root 24 and the second blade root (not shown) are fixed to the first blade holder 46 and the second blade holder (not shown), respectively. In this way, the actuator 44 is operably coupled to the blade 14 and configured to deform the blade 14.

[0059] Figure 6 is a schematic cross-sectional view of another assembly 8 comprising a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 largely corresponds to the propeller 10 described in relation to Figure 1, and the actuator largely corresponds to the actuator described in relation to Figure 5. The propeller 10 differs in that a first hub portion 28 is connected to a second hub portion 30 by a helical coupling 84 centered on the propeller centerline 16. This allows the first hub portion 28 to rotate around the propeller centerline 16 and to move along the propeller centerline 16 relative to the second hub portion 30. Thus, the actuator 44 is configured to change the relative orientation and position of the first hub portion 28 and the second hub portion 30.

[0060] The first blade fixing device 46 is connected to the hub 12 by a spherical coupling 86, and the second blade fixing device 48 is connected to the hub 12 by a linear coupling 88 positioned along a certain angle from the propeller centerline 16. The first blade root 24 and the second blade root 26 are fixed to the first blade fixing device 46 and the second blade fixing device 48, respectively. In this way, the orientation of the first blade root 24 and the position of the second blade root 26 are variable with respect to the hub 12. The first hub section 28 interconnects the first blade fixing device 46 and the actuator 44, and the second hub section 30 interconnects the second blade fixing device 48 and the actuator 44. Therefore, the first blade root 24 is configured to passively change its orientation relative to the first hub section 28 and, furthermore, its orientation relative to the hub 12 when the actuator 44 is operated. Similarly, the second blade root 26 is configured to passively change its position relative to the second hub portion 28. This means that the actuator 44 is configured to deform the blade 14 by actively moving the first hub portion 28 relative to the second hub portion 30 and passively moving the first blade root 24 and the second blade root 26.

[0061] Figure 8 is a schematic cross-sectional view of another assembly 8 of a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 3, and the actuator generally corresponds to the actuator described in relation to Figure 7. The propeller 10 differs in that the first blade fixture 46 and the second blade fixture 48, each of them, are connected to the hub 12 by a rotary coupling 72 having a tilt axis 90 parallel to the propeller centerline 16. The pin 80 of the mechanical connection 60 that transmits work from the actuator 44 to the blades 14 extends perpendicular to the tilt axis 90 and radially inward with respect to the propeller centerline 16. The yoke 78 is configured to cam the pin 80, causing the first blade fixture 46 and the second blade fixture 48 to tilt in opposite directions around their respective tilt axes 90. The first blade root 24 and the second blade root 26 are fixed to the first blade fixing device 46 and the second blade fixing device 48, respectively. This means that the actuator 44 is configured to deform the blade 14 by actively changing the orientation of the first blade fixing device 46 and the second blade fixing device 48, as well as the orientation of the first blade root 24 and the second blade root 26.

[0062] Figure 9 is a schematic cross-sectional view of another assembly 8 of a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 3, and the actuator generally corresponds to the actuator described in relation to Figure 7. The propeller 10 differs in that the first blade fixture 46 is connected to the hub 12 by a rotary coupling 72 having a tilt axis 90 perpendicular to the propeller centerline 16. The pin 80 of the mechanical connection 60 that transmits work from the actuator 44 to the first blade root 24 is mounted on the yoke 78 and extends parallel to the tilt axis 90. The first blade fixture 46 is configured to cam relative to the pin 80 when the actuator 44 is operated, causing the first blade fixture 46 to tilt longitudinally relative to the hub 12. The pin 80 of the mechanical connection 60 that transmits work from the actuator 44 to the second blade root 26 is configured as described in relation to Figure 7. The first blade root 24 and the second blade root 26 are fixed to the first blade fixing device 46 and the second blade fixing device 48, respectively. In this way, the actuator 44 is configured to deform the blade 14 by actively changing the orientation of both the first blade fixing device 46 and the second blade fixing device 48.

[0063] Figure 10 is a schematic cross-sectional view of another assembly 8 of a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 3, and the actuator generally corresponds to the actuator described in relation to Figure 7. The propeller 10 differs in that a first blade fixture 46 is connected to the hub 12 by a linear coupling 88 configured to move the position of the first blade fixture 46 radially with respect to the propeller centerline 16. The propeller 10 further differs in that a second blade fixture 48 is connected to the hub 12 by a linear coupling 88 configured to move the position of the first blade fixture 46 along the propeller centerline 16. A pin 80, which forms part of the mechanical connection 60 that transmits work to the first blade root 24, extends perpendicular to the propeller centerline 16, and the yoke 78 is configured to cam the pin 80 when the actuator 44 is operated, causing the first blade fixture 46 to move radially relative to the hub 12. The other yoke 78 is fixed to the second blade fixture 48 and is therefore configured to move the position of the second blade fixture 48 parallel to the propeller centerline 16. The first blade root 24 and the second blade root 26 are fixed to the first blade fixture 46 and the second blade fixture 48, respectively. In this way, the actuator 44 is configured to deform the blades 14 by actively changing the positions of both the first blade fixture 46 and the second blade fixture 48.

[0064] Figure 11 is a schematic cross-sectional view of another assembly 8 of a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 3, and the actuator generally corresponds to the actuator described in relation to Figure 7. The propeller 10 differs in that a first blade fixture 46 is connected to the hub 12 by a restricted cylindrical coupling 106 that allows movement parallel to and tangential to the propeller centerline 16. A second blade fixture 48 is fixed to the hub 12. The propeller further differs in that the mechanical connection 60 that transmits work to the first blade root 24 has a helical coupling 92 that is centered on the propeller centerline 16 and connects the piston rod 56 to the hub 12. When the actuator 44 is actuated, the piston rod 56 rotates around the propeller centerline 16 and moves parallel to the propeller centerline 16. The first blade holder 46 is fixed to a single yoke 78 of the mechanical connection 60. The first blade root 24 is fixed to the first blade holder 46, and therefore the actuator is configured to deform the blade 14 by actively changing the position of the first blade holder 46.

[0065] Figure 12 is a schematic cross-sectional view of another assembly 8 of a variable toroidal propeller 10 and an internal hydraulic actuator 44. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 1, and the actuator generally corresponds to the actuator described in relation to Figure 6. Instead of directly connecting the first hub portion 28 and the second hub portion 30, the helical coupling 84 connects the first hub portion 28 to the piston rod 56, which is fixed to the second hub portion 30. The first hub portion 28 and the second hub portion 30 are directly connected by a cylindrical coupling 94. When the actuator 44 is operated, the first hub portion 28 moves along the propeller centerline 16 relative to the second hub portion 30 and rotates around the propeller centerline 16.

[0066] The propeller 10 further differs in that the first blade fixture 46 is connected to the first hub portion 28 by a first rotary coupling 72 so that the first blade fixture 46 is perpendicular to the propeller centerline 16 and can rotate around a first blade axis 74 that intersects the propeller centerline 16. This corresponds to the first blade fixture 46 described in relation to Figure 7. The second blade fixture 48 is fixed to the second hub portion 30 as described in relation to Figure 1. The first hub portion 28 and the second hub portion 30 form part of a mechanical connection 60 that transmits work from the actuator 44 to the blades 14. A single yoke 78 and pin 80 of the mechanical connection 60 are configured to rotate the first blade fixture 46 when the position and orientation of the first hub portion 28 and the second hub portion 30 change. The first blade root 24 and the second blade root 26 are fixed to the first blade fixing device 46 and the second blade fixing device 48, respectively. In this way, the actuator 44 is operably coupled to the blade 14 and configured to deform the blade 14.

[0067] Figure 15 is a perspective view of the blades 14 and hub 12 of a variable toroidal propeller 10. The propeller 10 largely corresponds to the propeller 10 described in relation to Figure 3, except that the blades 14 are made of stainless steel instead of carbon fiber reinforced polymer. The propeller 10 is further an articulated structure consisting of a first blade segment 96, a second blade segment 98, and an interconnected articulated joint 100 in the form of a hinge joint. The articulated joint 100 has a rotation axis 102 along the first side 36 and second side 38 of the blade 14. The articulated joint 100 is located at the blade tip 22, meaning that the first blade segment 96 and the second blade segment 98 correspond to the first blade portion 18 and the second blade portion 20 described above, respectively.

[0068] Figure 16 is a perspective view of the blades 14 and hub 12 of a variable toroidal propeller 10. The propeller 10 is largely the same as the propeller 10 described in relation to Figure 15, but differs in that the interconnecting articulation joint 100 has a rotation axis 102 that crosses the first side 36 and second side 38 of the blade 14, and the first blade segment 96 and the second blade segment 98 overlap at the articulation joint 100. The propeller 10 further differs in that the second blade portion 20 is divided into the first blade segment 96 and the second blade segment 98.

[0069] Figure 17 is a perspective view of the blades 14 and hub 12 of the variable toroidal propeller 10. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 2. The propeller 10 differs in that it is made of unreinforced polymer and that the propeller 10 is an articulated structure composed of a first blade segment 96, a second blade segment 98, and an interconnected articulated joint 100 in the form of a spherical joint. The articulated joint 100 is located at the blade tip 22, meaning that the first blade segment 96 and the second blade segment 98 correspond to the first blade portion 18 and the second blade portion 20 described above, respectively. The blade 14 further differs in that it tapers towards the blade tip 22, and the chord length at the blade tip 22 is approximately 50% of the maximum chord length of the blade 14. The propeller further differs in that, instead of a straight joint 50, it has a cam joint 106 between the first hub portion 28 and the second hub portion 30. The cam joint 106 is configured to rotate the first hub portion 28 and the second hub portion 30 relative to each other around the propeller centerline 16 when the actuator 44 shown in Figure 13 moves the relative positions of the first hub portion 28 and the second hub portion 30 along the propeller centerline 16.

[0070] Figure 18 is a perspective view of the blades 14 and hub 12 of a variable toroidal propeller 10. The propeller 10 generally corresponds to the propeller 10 described in relation to Figure 3. The blades 14 differ in that they have a stainless steel protective shield 104 that protects the carbon fiber reinforced polymer that mainly forms the blades 14. The shield 104 is positioned at the leading edge 32 of the blade 14 and is in the form of a folded sheet around it, thus protecting the carbon fiber reinforced polymer from vortex cavitation at the tip. [Explanation of Symbols]

[0071] 8 Assembly 10 propellers 12 hubs 14 feathers 16. Propeller centerline 18. First wing section 20 Second wing section 22 blade tips 24. Base of the first feather 26. Base of the second wing 28. First hub section 30 Second hub section 32 Leading edge 34 Trailing edge 36. First Aspect 38. Second Aspect 40-wing forward-facing surface 42-wing reversed surface 44 Actuators 46 First wing fixing device 48. Second wing fixing device 50 Straight joint 52 cylinders 54 Double-acting piston 56 Piston Rod 58 Hydraulic conduit 60 Mechanical connection 62 Protrusion 64 Arms 66 Rotation axis 68 Bearings 70 Propeller shaft 72 Rotary joint 74. First blade axis 76 Second wing axis 78 York 80 pins 82 Hollow Rod 84. Helical joint 86. Spherical joint for blade fixing device 88. Linear joint for blade fixing device 90° Tilt Axis 92 Spiral joint 94 Cylindrical joint 96 First wing segment 98 Second wing segment 100 Joints 102 Rotation axis 104 Protective Shield 106 Cam joint

Claims

1. - Hub (12) and, - Toroidal propeller blades (14) connected to the hub (12) and Equipped with, A variable toroidal propeller (10) wherein the hub (12) is configured to operably connect the blades (14) to an actuator (44), and the blades (14) are configured to deform when the actuator (44) is operated.

2. The variable toroidal propeller according to claim 1, wherein the blade (14) has a blade tip (22) and is composed of a first blade portion (18) and a second blade portion (20) connected at the blade tip (22), the blade (14) comprises a first blade root (24) and a second blade root (26), the first blade root (24) connects the first blade portion (18) to the hub (12), the second blade root (26) connects the second blade portion (20) to the hub (12), and the actuator (44) is configured to deform the first blade portion (18).

3. The variable toroidal propeller (10) according to claim 2, wherein the blade (14) has a blade advance surface (40), and the blade (14) is configured to cooperate with the actuator (44) to change the shape of the blade advance surface (40) in the blade cross-section of the first blade portion (18).

4. The variable toroidal propeller (10) according to claim 3, wherein the blade (14) has a blade tip (22), and the cross-section of the blade is the cross-section at the blade tip (22).

5. A variable toroidal propeller (10) according to any one of claims 2 to 4, wherein the blade (14) is configured to cooperate with the actuator (44) to change the pitch of the first blade portion (18) and / or the second blade portion (20) when the actuator (44) is operated.

6. A variable toroidal propeller (10) according to any one of claims 2 to 5, wherein the first blade root (24) and the second blade root (26) are separated at the hub (12).

7. A variable toroidal propeller (10) according to any one of claims 2 to 6, wherein the hub (12) comprises a first hub portion (28) and a second hub portion (30), the first hub portion (28) and the second hub portion (30) being structurally separate and having an adjustable relative orientation and / or position, the first blade root (24) being connected to the first hub portion (28), the second blade root (26) being connected to the second hub portion (30), and the actuator (44) being configured to change the relative orientation and / or position of the first hub portion (28) and the second hub portion (30).

8. The variable toroidal propeller (10) according to claim 7, wherein the first blade root (24) is fixed to the first hub portion (28).

9. A variable toroidal propeller (10) according to any one of claims 2 to 7, wherein the hub (12) includes a first blade fixing device (46) that connects the first blade root (24) to the hub (12), the first blade fixing device (46) is configured to be operably connected to the actuator (44), and the first blade fixing device (46) is configured to change its orientation and / or position relative to the hub (12) when the actuator (44) is operated.

10. The variable toroidal propeller (10) according to claim 9, wherein the first blade fixing device (46) is configured to rotate and / or tilt relative to the hub (12) when the actuator (44) is operated.

11. The variable toroidal propeller (10) according to claim 9 or 10, wherein the first blade fixing device (46) is configured to move its position relative to the hub (12) when the actuator (44) is operated.

12. The variable toroidal propeller (10) according to any one of claims 1 to 11, wherein the blades (14) are integrally constructed and made of a fiber-reinforced polymer.

13. The variable toroidal propeller (10) according to any one of claims 1 to 11, wherein the blade (14) is an articulated structure and is made of metal.

14. The variable toroidal propeller (10) according to claim 13, wherein the blade (14) comprises a first blade segment (96), a second blade segment (98), and an articulated joint (100), the first blade segment (96) and the second blade segment (98) being arranged side by side and interconnected by the articulated joint (100).

15. An assembly (8) comprising a variable toroidal propeller (10) and an actuator (44) according to any one of claims 1 to 14, wherein the actuator (44) is operably coupled to the blade (14) and configured to deform the blade (14).

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