Magnus rotor, associated assembly and mechanism

Abstract

A Magnus rotor includes a rotor rotatable about a rotor axis and having an outer surface defining a rotor diameter and an inner running surface defining a running surface diameter not greater than 80% of the rotor diameter; a support structure configured to rotatably support the rotor; and a plurality of wheels, each wheel rotatably mounted to the support structure so as to rotate about a respective wheel axis extending substantially parallel to the rotor axis, and positioned such that the wheel rolls against the inner running surface as the rotor rotates about the support structure. The present disclosure further relates to a wheel assembly, a drive assembly, a biasing assembly and a universal wheel mechanism for a Magnus rotor.

Description

Technical Field

[0001] A Magnus rotor, also known as a rotor sail or Flettner rotor, is a marine propulsion system that uses a rotating cylinder to generate forward driving force instead of traditional sails or engines. Background Art

[0002] The basic principle behind the Magnus rotor is the Magnus effect, which describes the force generated by a rotating cylinder as it moves through a fluid. In the case of a Magnus rotor, the rotating cylinder (referred to as the rotor) is vertically placed on the deck of a ship or vessel, i.e., its axis of rotation is vertically upward. An engine or electric motor is used to rotate the rotor, thereby generating a lift force that propels the ship forward. This lift force is generated by the pressure difference between the front and back of the rotating cylinder, which creates a horizontal force perpendicular to the wind direction.

[0003] One of the main benefits of the Magnus rotor is its potential to reduce fuel consumption and emissions in the shipping industry, thus saving significant costs for shipping companies and reducing greenhouse gas emissions. This is particularly important because the emissions from the shipping industry account for a large proportion of global emissions, and the issue of emissions reduction in the shipping industry is receiving increasing attention. By using one or more Magnus rotors to replace or supplement the traditional propeller-driven propulsion force, the fuel required to propel the ship can be greatly reduced.

[0004] However, the Magnus rotors known in the art have their limitations. Specifically, due to the relatively high degree of wear experienced by the Magnus rotors, a large amount of maintenance work may be required. To give some examples, the bearing components that support the rotor must bear the static weight of the rotor, transfer the propulsion force to the ship structure, absorb the vibrations caused by rotor imbalance, and withstand other periodic and / or stresses caused by variable winds or the movement of the ship on the high seas. Additionally, the components exposed to the marine environment can cause additional wear and corrosion due to seawater and debris entering the moving parts of the Magnus rotor. A failure of the Magnus rotor can cause significant damage, and the ship will be forced to revert to using less efficient fuel engines and propellers.

[0005] Therefore, there is a need for a more efficient Magnus rotor configuration that operates more reliably and has fewer maintenance requirements. Summary of the Invention

[0006] According to a first aspect, there is provided a Magnus rotor, the Magnus rotor comprising: a rotor rotatable about a rotor axis, and an outer surface of the rotor defining a rotor diameter, and an inner running surface of the rotor defining a running surface diameter not greater than 80% of the rotor diameter; a support structure configured to rotatably support the rotor; and a plurality of wheels, each wheel rotatably mounted to the support structure to rotate about a respective wheel axis extending substantially parallel to the rotor axis and positioned such that when the rotor rotates about the support structure, the wheels roll against the inner running surface.

[0007] Preferably, the running surface diameter is not greater than 70% of the rotor diameter; more preferably not greater than 60% of the rotor diameter. Compared with the rotor diameter, the running surface diameter is smaller, so that at a given rotor angular velocity, the plurality of wheels rotate at a lower rotational speed. This reduces fatigue, wear, heat generation and noise.

[0008] Preferably, a wheel diameter defined by an outer surface of each wheel is at least 10% of the rotor diameter. The larger the wheel diameter, this also results in the corresponding wheel rotating at a lower rotational speed at a given rotor angular velocity, thereby reducing fatigue, wear, heat generation and noise.

[0009] Preferably, the plurality of wheels are spaced apart from each other about a pitch circle such that each wheel axis extends through the pitch circle; and a pitch circle diameter defined by the pitch circle is not greater than 70% of the rotor diameter; preferably not greater than 50% of the rotor diameter.

[0010] The pitch circle diameter substantially represents the running surface diameter and the wheel diameter considered in combination. In other words, for a given rotor (with a consistent rotor diameter), a smaller running surface diameter and a larger wheel diameter both result in a smaller pitch circle diameter. Therefore, a smaller pitch circle diameter of a given rotor also results in the plurality of wheels rotating at a lower rotational speed at a given rotor angular velocity, thereby reducing fatigue, wear, heat generation and noise.

[0011] Preferably, the support structure includes a hollow tower, a wall of the hollow tower having a substantially circular cross-sectional shape; and at least one of the plurality of wheels is at least partially located within an outer diameter of the tower. Positioning the wheel partially within the tower makes the tower wider and provides greater stiffness and strength to the support structure. The wheel can be positioned in a recess or groove within the tower.

[0012] Preferably, one or more of the wheels that are at least partially located within the outer diameter of the tower are positioned such that most of the wheel or each wheel is located within the outer diameter of the tower. Positioning the wheels within the tower such that most of them are within the tower further increases the possible size of the tower. Preferably, at least 60%, at least 70% or at least 80% of one or more of the wheels are located within the outer diameter of the tower.

[0013] Preferably, the rotor further includes a bearing ring, an inner surface or an outer surface of which is the internal running surface of the rotor; and a radial flange, which is configured to be annular, wherein an inner edge is connected to the outer surface of the bearing ring and an outer edge is connected to the inner surface of the rotor. A solid annular flange can provide greater stiffness and strength than alternatives such as a network of struts.

[0014] Preferably, the radial flange includes a passage. This enables personnel and maintenance systems to access the support structure and the interior of the rotor located above the bearing ring.

[0015] Preferably, the axial height of at least one wheel is at least 50% of the diameter of the wheel. This reduces the contact stress within the wheel when the wheel rolls compared to a shorter wheel, and thus fewer wheels are used at a given limiting contact stress.

[0016] Preferably, at least one wheel includes a substantially cylindrical outer surface. This minimizes the contact stress compared to the profile of a curved-surface wheel or a crowned wheel having contact points, and thus reduces wear and heat generation associated with hysteresis.

[0017] Preferably, at least one wheel includes a solid tire; preferably a solid tire including polyurethane or a fully polyurethane solid tire. For example, a solid tire has better wear resistance, higher load-carrying capacity and lower parasitic losses during rolling compared to a hollow pneumatic tire.

[0018] Preferably, when the rotor is in use, the internal running surface is located in the lower part of the rotor. For example, the internal running surface is located in the bottom 50% of the rotor; optionally in the bottom 30% of the rotor; or even in the bottom 10% of the rotor. This means that the plurality of wheels can be mounted in corresponding lower positions on the support structure. The wheels and the associated mechanisms (not shown) for driving / locating / suspending the wheels can be one of the heaviest components of the Magnus rotor, and thus, by mounting the wheels as close as possible to the deck level, the cost of the support structure can be significantly reduced.

[0019] According to a second aspect, there is provided a wheel assembly for a Magnus rotor, the wheel assembly comprising: a support structure; and a plurality of wheels mounted to the support structure so as to be unevenly spaced from each other, each wheel being rotatable in use to roll against a running surface of the rotor as the rotor rotates.

[0020] Such a wheel assembly allows a given number of wheels to be deployed in the most cost-effective manner by deploying more wheels in the high loading areas and fewer wheels in the low loading areas, thereby avoiding the additional cost of unnecessary wheels in the low loading areas.

[0021] Preferably, each wheel of the plurality of wheels has at least one of the following:

[0022] a height that is substantially the same as the height of each other wheel of the plurality of wheels;

[0023] a diameter that is substantially the same as the diameter of each other wheel of the plurality of wheels;

[0024] a weight that is substantially the same as the weight of each other wheel of the plurality of wheels; and

[0025] a material composition that is substantially the same as the material composition of each other wheel of the plurality of wheels.

[0026] In some instances, a Magnus rotor comprising the wheel assembly according to the second aspect of the present invention may additionally include one or more spacer wheels that may be configured to perform a separate function with respect to the plurality of wheels described above. For example, one or more spacer wheels may simply be included to provide aesthetic symmetry to the Magnus rotor. Such spacer wheels may be a cheaper alternative to the wheels included in the wheel assembly of the second aspect of the present invention. For example, the spacer wheels may be smaller, lighter, made of a cheaper material, and / or configured to carry a significantly lower load than the wheels of the wheel assembly. It should be understood that since such spacer wheels perform a different function from the wheels of the wheel assembly, non-uniform spacing is not considered.

[0027] Preferably, the wheel assembly has: a rear half that is oriented towards the stern of the ship in use; and a front half that is oriented towards the bow of the ship in use, and the front half contains fewer wheels than the rear half. The purpose of the rotor is to assist ship propulsion, and thus the control system is designed to ensure that the thrust load is almost entirely concentrated on the rear side of the rotor (the side away from the direction of travel of the ship). Removing the excess wheels in the front half reduces the rolling resistance of the wheel assembly.

[0028] It will be understood that in some instances, one or both wheels may be positioned such that they span from the front half to the back half of the wheel assembly. In such instances, the fraction of each wheel located in each half may be counted based on the cross-sectional area of the wheel. For example, if there are a total of six wheels, two wheels in the front half, three wheels in the back half, and one wheel is positioned horizontally such that 50% of the wheel is located in each half, then the front half may be considered to have 2.5 wheels and the back half may be considered to have 3.5 wheels.

[0029] The front half may have a front wheel density defined by the number of wheels in each support structure in the front half, and the back half may have a rear wheel density defined by the number of wheels in each support structure in the back half.

[0030] Preferably, the front wheel density is not greater than 75% of the rear wheel density. More preferably, the front wheel density is not greater than 67% of the rear wheel density.

[0031] Preferably, the front half includes a passage located between two adjacent wheels. Compared with a conventional wheel assembly with evenly spaced wheels, the lower wheel density in the front half creates space for equipment and personnel access, as well as for cables and pipes.

[0032] Preferably, the support structure includes a plurality of loading arrangements, each configured to urge the corresponding wheel towards the running surface in use; and at least one loading arrangement urges the corresponding wheel towards the running surface according to a first loading characteristic, and at least one other loading arrangement urges the corresponding wheel towards the running surface according to a second different loading characteristic. In some instances, the loading characteristic refers to the effective stiffness of the loading arrangement. However, in other instances, such as in the case of using a fluid actuator, the loading arrangement does not have a defined stiffness parameter, and the loading characteristic refers to the relationship between the loading force and the displacement of the loading arrangement. Using different loading characteristics for different wheels can avoid resonance modes for all thrust directions, since the loading may be unevenly distributed between the wheels.

[0033] Preferably, the first loading characteristic results in a lower degree of bias applied compared to the second loading characteristic; and at least one loading arrangement in the back half is configured to urge the corresponding wheel according to the first loading characteristic, and at least one loading arrangement in the front half is configured to urge the corresponding wheel according to the second loading characteristic. Since there are fewer front wheels and they are rarely heavily loaded, it may be beneficial to have a higher loading characteristic (such as a stiffer spring) compared to the rear wheels.

[0034] Preferably, each loading arrangement in the rear half is configured to push the corresponding wheel according to the first loading characteristic, and each loading arrangement in the front half is configured to push the corresponding wheel according to the second loading characteristic. Using one set of loading arrangements in the front half and another set in the rear half can address the different wheel densities and loading issues in the front and rear halves without unduly complicating the design and maintenance of the wheel assembly.

[0035] Preferably, the first loading characteristic and the second loading characteristic replicate a first stiffness and a second stiffness, respectively. As previously described, while some components such as springs have inherent stiffness characteristics, other components such as fluid actuators and servo systems do not. However, the loading characteristics of such other components can be controlled to replicate the behavior of a spring. For example, a servo system can be controlled to apply a force proportional to the measured extension or displacement of the servo system, where the proportionality constant is equal to the stiffness of the spring.

[0036] According to a third aspect, there is provided a drive assembly for a Magnus rotor, the drive assembly comprising: one or more drive wheel mechanisms, each drive wheel mechanism including a drive wheel and a drive mechanism, the drive wheel being locatable to roll against a running surface of the rotor in use, the drive mechanism for supplying torque to drive the drive wheel to rotate and drive the rotor to rotate in use; and one or more idler wheel mechanisms, each idler wheel mechanism including an idler wheel, the idler wheel being freely rotatable and locatable to roll against the running surface of the rotor in use when the rotor rotates, wherein: at least one drive wheel includes a first tire having a first tire composition, and at least one idler wheel includes a second tire having a second tire composition different from the first tire composition; and / or at least one drive wheel mechanism further includes a biasing mechanism configured to bias the corresponding drive wheel towards the running surface in use, the biasing mechanism being configured to increase the degree of biasing applied as the torque supplied by the drive mechanism increases.

[0037] In some instances, the one or more drive wheels and the one or more idler wheels may be locatable to roll against the same running surface of the rotor in use. In other instances, the one or more drive wheels may be locatable to roll against a first running surface of the rotor in use, while the one or more idler wheels may be locatable to roll against a second running surface of the rotor different from the first running surface in use.

[0038] Preferably, the first tire is a pneumatic tire.

[0039] Preferably, the first tire composition is formed of a material being or including a rubber material.

[0040] Preferably, the second tire is a solid tire.

[0041] Preferably, the second tire assembly is formed of a material being or including a polyurethane material and / or a metal material.

[0042] Preferably, the Shore hardness of the polyurethane material is 70A or higher.

[0043] Preferably, the Brinell hardness of the metal material is 100HB or higher.

[0044] Preferably, the drive assembly further includes a support structure, on which the one or more drive wheel mechanisms and the one or more idler wheel mechanisms are mounted, wherein at least one biasing mechanism includes a swing chassis pivotally connecting a corresponding drive wheel to the support structure, and the biasing mechanism is configured to bias the swing chassis to pivot relative to the support structure such that the drive wheel is pushed against the running surface. This ensures that sufficient contact force is maintained between the drive wheel and the running surface to prevent slipping, without causing excessive wear to the wheel or the running surface when the torque supplied by the drive mechanism increases.

[0045] According to a fourth aspect, there is provided a biasing assembly for a wheel of a Magnus rotor, the biasing assembly comprising: a first coupling that can be connected to a support structure to mount one or more wheels relative to a vessel; a second coupling that can be connected to a wheel rotatable about a wheel axis, whereby in use when the rotor rotates about the rotor axis, the wheel rolls against a running surface of the rotor; and a biasing member that interconnects the first coupling and the second coupling and is configured to, in use, push the wheel axis towards the running surface with a force related to displacement, wherein when the wheel axis is in a first displacement region, the biasing member pushes the wheel towards the running surface according to a first force characteristic, and when the wheel axis is in a second displacement region, the biasing member pushes the wheel towards the running surface according to a second different force characteristic.

[0046] Preferably, in use, the first displacement region is closer to the running surface in a neutral position than the second displacement region. The running surface can be considered to be in a neutral position when no external load is applied. In some instances, the running surface can be an inward-facing surface, in which case the first displacement region will be further from the rotor axis than the second displacement region. In other instances, the running surface can be an outward-facing surface, in which case the first displacement region will be closer to the rotor axis than the second displacement region.

[0047] Preferably, the first force characteristic results in a lower degree of biasing being applied compared to the result of the second force characteristic.

[0048] Preferably, the first displacement region transitions to the second displacement region at a predetermined transition point. The biasing assembly may be configured in use such that, with zero external loading applied, the wheel axis is located at the transition point.

[0049] Preferably, the biasing assembly includes a first biasing element defining the first force characteristic and a second biasing element defining the second force characteristic.

[0050] Preferably, the first biasing element is or includes a spring, a pneumatic actuator, and / or a hydraulic actuator. For example, the spring may be a helical spring or a leaf spring.

[0051] Preferably, the first biasing element is or includes a pneumatic actuator or a hydraulic actuator having a pressure accumulator.

[0052] Preferably, the second biasing element is or includes an elastomeric block, preferably formed of or including an elastomeric material.

[0053] Preferably, the second force characteristic is selected to prevent the rotor from generating resonant oscillations within the desired operating speed range in use.

[0054] According to a fifth aspect, a wheel assembly for a Magnus rotor, the wheel assembly comprising: a support structure defining a pitch circle; at least one wheel mounted to the support structure and rotatable about a wheel axis to roll against a running surface of the rotor in use when the rotor rotates; and at least one biasing assembly according to any example of the fourth aspect, wherein the first coupling or each first coupling is connected to the support structure and the second coupling or each second coupling is connected to a respective wheel.

[0055] The at least one wheel may be a plurality of wheels and the at least one biasing assembly may be a respective plurality of biasing assemblies. The second force characteristic of the biasing assembly may replicate stiffness, and the second force characteristics of the plurality of biasing assemblies may replicate a stiffness effective on the rotor in use, the stiffness being greater than the desired moving mass of the rotor multiplied by the square of the desired maximum operating angular velocity of the rotor.

[0056] Preferably, the stiffness effective on the rotor in use is 1.5 to 10 times the effective moving mass of the rotor multiplied by the square of the maximum operating angular velocity of the rotor. Preferably, the stiffness effective on the rotor in use is 2 to 5 times the effective moving mass of the rotor multiplied by the square of the maximum operating angular velocity of the rotor.

[0057] According to a sixth aspect, there is provided a caster mechanism for a Magnus rotor, the caster mechanism comprising: a wheel rotatable about a wheel axis to roll against a running surface of the rotor as the rotor rotates about a rotor axis in use; a mounting assembly rotatably supporting the wheel relative to a support structure in use and including a gimbal support configured to allow the wheel axis to pivot about a gimbal axis extending substantially perpendicular to the wheel axis, wherein in use, the wheel axis and the rotor axis extend along a common radial plane, and the gimbal support is configured such that the gimbal axis additionally extends perpendicular to the radial plane.

[0058] Preferably, an outer surface of the wheel is substantially cylindrical such that in use, a contact line or contact area is established between the wheel and the running surface, the length of the contact line or contact area being substantially equivalent to the height of the wheel, and the center of the contact line or contact area representing the center of force between the wheel and the running surface.

[0059] Preferably, the height of the wheel is equal to or greater than 50% of the diameter of the wheel.

[0060] The gimbal axis may extend closer to the contact line or contact area than the wheel axis; preferably, the gimbal axis extends through the contact line or contact area; more preferably, the gimbal axis extends through the center of force. It will be understood that the gimbal axis extending generally through the center of force means that the gimbal axis extends close enough to the center of force such that for the function of the caster mechanism, this difference is negligible.

[0061] Preferably, the gimbal support defines a first pivot point and a second pivot point, whereby the gimbal support provides a gimbal support force acting along a gimbal support axis extending through the first pivot point and the second pivot point; and the pivot points are arranged relative to each other such that the gimbal support axis coincides with the center of force. The gimbal support axis may coincide directly with the center of force or may coincide substantially with the center of force in the sense that the gimbal support axis extends close to the center of force.

[0062] Preferably, the caster mechanism further includes a biasing support configured to resist pivoting of the wheel axis about the gimbal axis. This advantageously prevents the wheel from undesirably rotating about the gimbal axis under the action of its own weight.

[0063] Preferably, the biasing support provides a biasing support force acting along the biasing support axis, the biasing support force counteracting a rotational force acting about the center of action of the caster mechanism, the rotational force being generated by the weight of the caster mechanism.

[0064] Optionally, the swivel axis extends closer to the center of gravity of the caster mechanism than the curved outer surface of the wheel. Preferably, the swivel axis extends substantially through the center of gravity of the caster mechanism. The swivel axis may extend directly through the center of gravity or approximately through the center of gravity in the sense that the swivel axis passes close to the center of gravity.

[0065] According to a seventh aspect, there is provided a Magnus rotor according to any example of the first aspect, wherein the plurality of wheels define one or more of the following:

[0066] a wheel assembly according to any example of the second aspect;

[0067] a drive assembly according to any example of the third aspect; and

[0068] a wheel assembly according to any example of the fifth aspect.

[0069] According to any example of the sixth aspect, at least one wheel may form part of the caster mechanism.

[0070] The features and advantages of the first to sixth aspects of the present disclosure and their embodiments will, with necessary modifications, apply to the seventh aspect of the present disclosure and its examples.

[0071] According to an eighth aspect, there is provided a Magnus rotor comprising:

[0072] a rotor rotatable about a rotor axis and having an inner running surface;

[0073] a support structure configured to rotatably support the rotor; and

[0074] a plurality of wheels, each wheel rotatably mounted to the support structure so as to rotate about a respective wheel axis extending substantially parallel to the rotor axis and positioned such that when the rotor rotates about the support structure, the wheels roll against the inner running surface,

[0075] the plurality of wheels define one or more of the following:

[0076] a wheel assembly according to any example of the second aspect;

[0077] a drive assembly according to any example of the third aspect; and

[0078] The wheel assembly according to any example of the fifth aspect.

[0079] According to any example of the sixth aspect, at least one wheel can form part of a swivel wheel mechanism.

[0080] The features and advantages of the second to sixth aspects of the present disclosure and their embodiments will, with necessary modifications, apply to the eighth aspect of the present disclosure and its examples.

[0081] Although the examples have so far referred to the application of the Magnus rotor in ship propulsion, it will be understood that the examples may also be applicable to other types of vessels or vehicles, such as aircraft and land vehicles. Brief Description of the Drawings

[0082] Figure 1(a) and 1(b) show simplified views of an exemplary Magnus rotor, where FIG. 1(a) is a cross-sectional view along a plane aligned with the rotational axis of the rotor, and FIG. 1(b) is a cross-sectional view along plane A-A of FIG. 1(a).

[0083] Figure 2 show exemplary wheels of a wheel assembly for a Magnus rotor.

[0084] Figure 3(a) and 3(b) show simplified cross-sectional views of an exemplary first wheel assembly and a second wheel assembly for a Magnus rotor, respectively, the wheel assemblies having uneven wheel spacing along a plane extending perpendicular to the rotational axis of the rotor.

[0085] Figure 4 schematically show an example of a drive assembly for a Magnus rotor passing through a plane extending perpendicular to the rotational axis of the rotor.

[0086] Figure 5(a) and 5(b) show an exemplary drive wheel mechanism of a drive assembly for a Magnus rotor, where FIG. 5(a) shows a cross-sectional view along a plane aligned with the rotational axis of the rotor, and FIG. 5(b) is a further cross-sectional view along plane B-B of FIG. 5(a).

[0087] Figure 6(a) and 6(b) show simplified views of a Magnus rotor including a plurality of first biasing assemblies, where FIG. 6(a) is a cross-sectional view along a plane aligned with the rotational axis of the rotor, and FIG. 6(b) shows an enlarged view of one of the first biasing assemblies of FIG. 6(a).

[0088] Figure 7 show formingFigure 6(a) and 6(b) A graph of the force F of a biasing member, which is part of the first biasing assembly shown, versus the linear displacement x.

[0089] Figure 8 An example of a second biasing assembly is shown.

[0090] Figure 9(a) and 9(b) shows Figure 1(a) and 1(b) A simplified view of a Magnus rotor when deflected under load, where Fig. 9(a) is a cross-sectional view along a plane aligned with the rotational axis of the rotor, and Fig. 9(b) shows an enlarged view of the wheel of the rotor of Fig. 9(a), a portion of the rotor, and the associated operating surface.

[0091] Figure 10 A first exemplary caster mechanism for a Magnus rotor is shown, where the caster axis is aligned with the center of gravity of the wheel.

[0092] Figure 11 A second exemplary caster mechanism for a Magnus rotor is shown, where the caster axis is aligned with the center of effort of the wheel. DETAILED DESCRIPTION

[0093] Magnus rotor

[0094] Referring Figure 1(a) and 1(b) , an exemplary Magnus rotor 100 consists of a rotor 101 that is rotatable about a rotor axis 101a (the rotational axis of the rotor). The rotor 101 is substantially cylindrical, where the outer wall 101b extends vertically and is parallel to the rotor axis, and the top disk 110 extends radially from the rotor axis 101a. The rotor 101 is supported by a support structure in the form of a bracket 105 that, in use, extends from a deck 106 of a vessel such as a ship. A driving torque can be applied to the rotor 101 to cause it to rotate about the bracket 105 (i.e., the support structure).

[0095] The rotor 101 includes a bearing ring 102 which is connected to the outer wall 101b of the rotor 101 by a radial flange 102b. The bearing ring 102 is positioned radially inwards from the outer wall 101b of the rotor 101 towards the carriage 105. In the illustrated embodiment, the bearing ring 102 is an annular ring having a rectangular cross-section. However, in other embodiments, the bearing ring may have a different shape, such as an I-shape or a hollow cross-section shape. The radial flange 102b engages the radially outermost edge of the bearing ring 102 with the rotor 101 such that the bearing ring 102 rotates together with the rotor 101. The radial flange 102b is a continuous annular ring like the bearing ring 102. This means that the radial flange 102b is connected to the bearing ring 102 and the rotor 101 along its entire circumference.

[0096] The bearing ring 102, the radial flange 102b and the rotor 101 can be connected together by welding or other fastening means. In some instances, the radial flange and the bearing ring 102 can be formed as a single component, such as a flange having a "T" - shaped cross-section, where the top edge of the "T" forms the inner surface of the bearing ring and the bottom edge of the "T" engages the rotor. In additional instances, the bearing ring and the radial flange can be integrally formed with the rotor.

[0097] In the illustrated embodiment, the above-mentioned inner surface of the bearing ring 102 defines an internal running surface 102a. The bearing ring 102 is brought into contact with a plurality of wheels 103 along its running surface 102a. The wheels 103 are rotatably mounted to, i.e., supported by, the carriage 105 such that the wheels rotate about their respective wheel axes 103a. The wheel axes 103a are arranged parallel to the rotor axis 101a in order to minimize wear between the bearing ring 102 and the wheels 103. The wheels 103 are positioned such that each wheel 103 rolls against the running surface 102a of the bearing ring 102 when the bearing ring 102 rotates. The wheels 103 are covered by the rotor 101, and specifically by the outer wall 101b of the rotor 101, so as to be protected from weather and seawater corrosion.

[0098] In this instance, the internal running surface 102a is located in the lower part of the rotor 101. That is to say, the internal running surface 102a is located in the lower 50% of the rotor 101. Accordingly, the plurality of wheels 103 are mounted in corresponding lower positions on the carriage 105. The wheels 103 and the associated mechanisms (not shown) for driving / positioning / suspending the wheels can be one of the heaviest components of the Magnus rotor, and thus, by mounting the wheels 103 close to the deck 106, the cost of the support structure can be significantly reduced. In other instances, the internal running surface can be located in a lower position, such as the bottom 30% of the rotor; or even the bottom 10% of the rotor.

[0099] In the illustrated embodiment, the running surface diameter D defined by the running surface of the bearing ring 102 运行 is not greater than 80% of the outer diameter of the outer wall 101b of the rotor 101 (i.e., not greater than 80% of the nominal rotor diameter D 转子 . Moreover, the wheel diameter D of each wheel 103 轮子 (which may or may not be defined by the outer surface or the tire surface of the wheel) is at least 10% of the rotor diameter D 转子 . A smaller running surface diameter D 运行 and / or a larger wheel diameter D 轮子 will cause the wheels 103 to rotate more slowly at a given angular velocity (i.e., rotational speed) of the rotor 101. This reduces fatigue, wear, heat generation, and noise. In other embodiments, the running surface diameter may be not greater than 70% or even 60% of the rotor diameter, thereby further reducing wear.

[0100] In an alternative embodiment, the outer surface of the bearing ring may define the internal running surface of the rotor. In such embodiments, the plurality of wheels will be arranged such that each wheel is positioned between the bearing ring and the rotor, or above or below a radial flange connecting the bearing ring and the rotor.

[0101] It should be understood that the nominal rotor diameter D 转子 is defined as the outer diameter of the outer wall 101b of the rotor 101, excluding the top plate 110. In the illustrated embodiment, the outer diameter of the outer wall 101b of the rotor 101 is substantially uniform along the height of the rotor. However, in other instances (not shown), the outer diameter of the outer wall of the rotor may vary along the height of the rotor. In such instances, the rotor diameter may be considered as the average outer diameter of the outer wall of the rotor, excluding the top plate.

[0102] In some instances, the rotor diameter is between 3 meters and 6 meters.

[0103] The plurality of wheels 103 are spaced apart about a pitch circle 104, which is represented by the dashed line in FIG. 1(b). The pitch circle 104 is centered on the rotor axis 101a, where the diameter is defined by the positions of the plurality of wheel axes 103a. That is, each wheel axis 103a is arranged to extend through the pitch circle 104. By circumferentially spacing the wheels 103 about the pitch circle, a plurality of contact points can be established between the circumference of the bearing ring 102, i.e., about its internal running surface 102a, and the bearing ring. This enables the transfer of lateral forces between the rotor 101 and the carriage 105 in a plurality of directions perpendicular to the rotor axis 101a.

[0104] For a given diameter D of the rotor 101 转子 , the diameter of the pitch circle 104 increases as the diameter D of each wheel 103 轮子decreases as it increases, or decreases as the operating surface diameter D defined by the operating surface 102a of the bearing ring 102 运行 decreases. Thus, the pitch circle 104 diameter D 节圆 is smaller, and correspondingly the wear and noise are smaller. Therefore, in some embodiments, the pitch circle diameter D of the pitch circle 104 节圆 is not greater than 70%, 60%, or even 50% of the diameter D 转子 of the rotor 101.

[0105] In the illustrated embodiment, the carriage 105 includes a hollow tower 105a, the wall of which has a substantially circular cross-sectional shape. For example, the tower 105a can be conical, or cylindrical, or elliptical as shown, or a combination including a cylindrical section and a conical section. A cross-sectional shape defined as a regular shape having five or more sides (e.g., pentagon, hexagon, heptagon, etc.) will be understood to be substantially circular in this context.

[0106] Additionally, in the illustrated embodiment, each of the plurality of wheels 103 is at least partially located within the tower 105a. That is, when viewed from above (as shown in FIG. 1(b)), the profile of each wheel 103 overlaps the profile of the tower 105a. This makes the tower 105a wider, and thus for a given pitch circle diameter D 节圆 of the wheels 103 arrangement, provides greater stiffness and strength to the carriage 105 and the plurality of wheels 103. In some other instances (not shown), the wheels can be positioned such that their wheel axes are located on the outer circumference of the tower (or, if the cross-section of the tower is polygonal rather than circular, the wheel axes are located on the circumference defined by the four corners of the polygon). In other words, in such other instances, the pitch circle coincides with the outer circumference of the tower. In still other instances, one or more wheels are positioned such that most of each wheel is located within the tower. In other words, the diameter of the pitch circle is smaller than the diameter of the tower and the carriage. Relative to a given pitch circle diameter, this further increases the diameter of the tower, and thus further reduces the bending stress generated by the load applied to the rotor 101. In some instances, 60%, 70%, or even 80% of the cross-section of each wheel is located within the outer circumference of the tower.

[0107] It can be understood that the outer circumference of the tower 105a can vary with height, for example, if the tower is conical as in the illustrated embodiment. Thus, when considering the position of the wheels 103 relative to the tower 105a, the outer circumference can be considered to be at the plane A-A, as shown in FIG. 1(a), i.e., the plane that is flush with the middle of the wheels 103.

[0108] In known Magnus rotors, passages can be provided within the carriage, for example, for maintenance personnel and the like to pass through. In the illustrated embodiment, since the bearing ring 102 limits the available space of the carriage 105, while the large-diameter wheels 103 and the associated machinery and support structures limit the space within the carriage 105, it can be challenging to provide a passage of a suitable size to allow passage through the carriage. This can complicate the maintenance of the Magnus rotor 100. Thus, in the illustrated embodiment, the radial flange 102b includes a passage 109 in the form of a flap, which is simply an opening extending through the radial flange 102b.

[0109] Providing the passage 109 through the radial flange 102b allows for a reduction in the diameter of the running surface 102b, i.e., a reduction in the running surface diameter D of the running surface 102a 运行 , and / or an increase in the wheel diameter, since the requirement for a passage within the carriage 105 can be eliminated.

[0110] In other instances, the passage can include a door, a baffle, or other movable closure means that can be used to seal the passage when not in use, thereby preventing air flow from circulating through the passage. The illustrated passage 109 is large enough to facilitate the passage of maintenance personnel to enter the internal space between the rotor 101 and the carriage 105. However, in other instances, the passage is smaller and sized to allow only tools and monitoring equipment (such as a camera) to enter, since although a larger passage 109 facilitates entry, it can potentially lead to an increase in the structural stress of the radial flange 102b.

[0111] In the illustrated exemplary embodiment, the carriage 105, and more specifically its tower 105a, contains corresponding housings 108 that enclose portions of each wheel within the tower 105a, such that each wheel 103 provides additional protection. (When considering the outer circumference of the tower 105a, any effect of the housing on the shape of the tower 105a is not considered.)

[0112] In the example shown in FIG. 1(a), an upper bearing assembly 107 is provided. Thus, the plurality of wheels 103, the bearing ring 102, and the radial flange 102b can be considered to together form a lower bearing assembly. In this example, the upper bearing assembly 107 is positioned at the top of the carriage 105 and is configured to support the axial loading of the rotor 101 (primarily the weight of the rotor 101 itself), which means that the bearing ring 102 and the wheels 103 (i.e., the lower bearing assembly) primarily transfer the lateral loading of the rotor 101. In some instances, the drive torque is provided to, i.e., applied to, the rotor through the upper bearing assembly, for example, by a drive shaft that is aligned with the rotor axis and extends upward through the carriage to connect to the rotor. In other instances, the drive torque is provided by one or more of the plurality of wheels 103, as will be discussed in further detail below.

[0113] Now refer to Figure 2 wherein, for any of the previously described instances or embodiments (including the illustrated embodiment), the wheel 203 is configured to rotate about a wheel axis 203a. The wheel has a wheel diameter D 轮子 and an axial height H (measured in the direction of the wheel axis 203a). The axial height H is at least 50% of the wheel diameter D 轮子 . That is, the wheel 203 is relatively tall compared to its diameter. This reduces the contact stress, thereby allowing fewer wheels to be used at a given limiting contact stress. For example, compared to shorter and flatter wheels known in the art

[0114] The outer surface 203b of the wheel 203 is configured to make rolling contact with the bearing ring 102, particularly the running surface 102a, without slipping or generating significant friction. To maximize the contact area while minimizing wear, the shape of the outer surface 203b can be matched to the shape of the running surface 102a of the bearing ring 102. In the illustrated example, the wheel 203 has a substantially cylindrical outer surface 203b configured to roll against the substantially flat running surface 102a of the bearing ring 102. Compared to the profile of a curved or crowned wheel, this wheel shape for the flat running surface 102a can minimize the contact stress and thus reduce wear and heat generation associated with hysteresis

[0115] Additionally, the illustrated wheel 203 includes a tire 203d coupled to the rim of the hub 203e. The hub 203e includes apertures 203c configured to receive the axle about which the wheel 203 rotates. In the illustrated example, the tire 203d is formed of polyurethane or a material including polyurethane. In other examples, the tire can be formed of a material including steel. Compared to other types of tires such as rubber tires, polyurethane tires have lower rolling resistance. Preferably, the tire 203d is as hard as possible to reduce the rolling resistance and heat generation caused by hysteresis of the tire 203d. One way to achieve this is to use a solid tire, and more specifically a solid polyurethane tire, rather than, for example, an inflatable tire, pneumatic tire, or hollow tire. For a given material, the stiffness of the tire 203d can be further increased by making the tire 203d as hard as possible and as thin as possible, thereby improving wear resistance and load capacity and reducing parasitic losses. The thermal stress on the tire 203d can be further reduced by using a hub 203e that includes a highly thermally conductive material such as aluminum. In this way, the heat generated by the rolling resistance can be quickly transferred out of the tire 203d, thereby extending the service life of the tire 203d

[0116] Wheel assembly

[0117] The wind and inertial loads applied to the rotor of a Magnus rotor are unevenly distributed around the circumference of the rotor. The purpose of the rotor is to assist in the propulsion of a ship or other vessel, and thus the associated control systems are typically designed to ensure that the thrust load is concentrated almost entirely on the rear side of the rotor (i.e., the side away from the direction of travel of the vessel), except for situations that occasionally arise due to instantaneous changes in wind direction. The inertial loads will be concentrated on the two sides of the rotor perpendicular to the direction of travel, as the rolling acceleration on a ship or other (e.g., marine) vessel is typically much higher than the pitch acceleration. Thus, when the wheels 103; 203 are evenly distributed around the pitch circle 104 (e.g., as shown in Figure 1(b)), the foremost wheels have the smallest average load, with both thrust and inertial forces being small.

[0118] Figure 3(a) shows an alternative and more efficient first wheel assembly 300a of a Magnus rotor. The first wheel assembly 300a includes a plurality of wheels 303 mounted to a support structure 302, which may or may not be or include a bracket 105, as shown in the exemplary Magnus rotor 100 of Figure 1(a) and 1(b) shown.

[0119] Each of the wheels 303 is rotatable such that, in use, the wheels roll against the running surface of the rotor (not shown in Figure 3(a)). Additionally, the wheels 303 have substantially the same height H (i.e., as defined with respect to the wheels 203 shown), and have substantially the same weight, and have substantially the same material composition, although this is not necessarily the case in other embodiments of the present invention. Figure 2 shown.

[0120] The front side, rear side, port side, and starboard side of the rotor are defined with respect to the direction of travel 301 indicated by the arrow. That is, it is assumed that the direction of travel of the ship is actually aligned with the bow of the ship (or other vessel). The support structure 302 and the wheel axes in this instance define a pitch circle 304, as previously described with respect to Figure 1(b). However, the wheels 303 are not evenly spaced circumferentially around the pitch circle 304, but are spaced unevenly from each other around the pitch circle 304. More specifically, in the regions of higher loading, i.e., the rear side of the rotor, as well as the port and starboard sides, the wheels 303 are spaced closer together, while at the front side of the rotor, they are spaced farther apart. In the example shown in Figure 3(a), this will effectively remove the foremost wheel 303. This creates space for equipment and personnel access, cables, and pipes within the support structure 302. Additionally, the excess costs associated with including the forward wheels (including equipment, installation, maintenance costs, and the weight of the wheels and their auxiliary equipment) are removed. Due to the removal of the excess wheels, the rolling resistance is also reduced, while the contact stress of the remaining wheels 303 does not increase significantly (since the wheels that are effectively removed do not carry a large load).

[0121] In other instances (not shown), the size of the wheels can vary, and thus the wheel axes may not be on a pitch circle. In such instances, the wheel spacing can alternatively be based on the spacing of the running surface around the adjacent contact points between the wheels and the running surface.

[0122] Returning to the shown wheel assembly 300a, it can be along the port-starboard midplane P of the associated rotor P-S divided into a front half H F and a rear half H S . Then, with respect to the front half H F and the rear half H A of the wheel assembly 300a, the wheel density can be defined as the number of complete wheels 303 per support structure 302 in each half H F 、H A . Thus, in the wheel assembly 300a of the first embodiment, the front wheel density is 3, because there are two wheels 303 completely located in the front half H F , and the leftmost wheel 303p and the rightmost wheel 303s are each counted as half a wheel, because they are both divided in half by the port-starboard midplane P P-S , that is, each wheel is located at half the position of the front half H F . Similarly, the rear wheel density is 4, because there are three complete wheels 303 and two half wheels 303p, 303s in the rear half H A . Thus, the front wheel density is 75% of the rear wheel density.

[0123] In addition to the above, in the wheel assembly 300a of the first embodiment, each wheel 303 is mounted to the wall of the support structure 302 by a mounting bracket 306 and a loading arrangement 307. Each wheel 303 is connected to the mounting bracket 306 by an axle 306a, and the wheel 303 can rotate about the axle. The mounting bracket 306 is in turn connected to the support structure 302 by the loading arrangement 307. The loading arrangement 307 pushes the wheel 303 radially outward, that is, towards the running surface against which the wheel 303 is configured to roll in use. That is to say, each loading arrangement 307 provides a radially outward force to the corresponding wheel 303, that is, each loading arrangement 307 can be regarded as biasing the corresponding wheel 303 towards the running surface in use. This ensures that, in use, an ideal degree of contact force is maintained between each wheel 303 and the running surface, while providing a restoring force for the wheel 303 to re-contact the running surface when the given wheel 303 is displaced due to, for example, bumps on the running surface.

[0124] The force exerted by the loading arrangement 307 on the wheels 303 can be in the form of a loading characteristic. In the illustrated embodiment, the loading arrangement 307 includes a pair of springs (although fewer or more than two springs can be utilized), and the pair of springs is configured to exert a tension that pulls the corresponding wheels 303 towards the running surface. The loading characteristic of such a loading arrangement 307 is the effective stiffness of the pair of springs. In another example (not shown), the loading arrangement 307 can alternatively include an active actuator, such as a computer-controlled piston. The loading characteristic of such a loading arrangement is the force exerted by the actuator (e.g., the piston) on the wheel, and the force can be configured as a function of the radial displacement of the wheel from the running surface.

[0125] To achieve the required minimum total effective stiffness, for example, to avoid resonance modes of the rotor of the Magnus rotor in all thrust directions, it may be advantageous for the loading characteristics of the unevenly distributed wheels 303 in the first type of wheel assembly as described above to be different at a given wheel position. For example, as shown, in the case where each loading arrangement 307 includes two springs, the loading arrangement 307 of each wheel 303 in the front half H F may have a higher spring stiffness due to the smaller number and less frequent heavy loading compared to the loading arrangement 307 of each wheel 303 in the rear half H A . That is, the loading characteristic (stiffness) of each loading arrangement 307 of the wheels 303 in the front half H F is higher than the loading characteristic of the wheels 303 in the rear half H A . Therefore, preferably, each loading arrangement of the wheels 303 in the front half H F has a first effective stiffness, and each loading arrangement of the wheels 303 in the rear half H A has a second effective stiffness, and more preferably, the first stiffness is greater than the second stiffness, although this is not necessarily the case.

[0126] FIG. 3(b) shows a second exemplary wheel assembly 300b similar to the first wheel assembly 300a, and similar features share the same reference numerals. Accordingly, in the second wheel assembly 300b, the wheels 303 are similarly unevenly spaced about a pitch circle 304 defined by the support structure 302, but for clarity, the similar mounting chassis and loading arrangement are omitted in FIG. 3(b).

[0127] In addition, as in the first wheel assembly 300a, the wheels 303 of the second wheel assembly 300b have substantially the same height H (i.e., as defined with respect to Figure 2 the shown wheel 203), and have substantially the same weight, and have substantially the same material composition, although this is not necessarily the case in other embodiments of the present invention.

[0128] Although the wheels 303 in the second wheel subassembly 300b are arranged to unevenly surround the pitch circle 304, they are alternatively arranged such that only a single wheel 303 is fully located in the front half H F and only two wheels 303 are fully located in the rear half H F According to the wheel density described previously, the front wheel density of the second wheel subassembly 300b is 2, and the rear wheel density is 3. Therefore, the front wheel density is approximately 67% of the rear wheel density. In other examples (not shown), the ratio between the front wheel density and the rear wheel density may even be lower. In the shown second wheel subassembly 300b, the thrust loading is typically transmitted through the two rear-most wheels 303, and the main inertial loading generated by rolling is transmitted through the left-most wheel 303p and the right-most wheel 303s, which means that the single front-most wheel 303 mainly only needs to transmit the low inertial loading generated by pitching.

[0129] The front half H of the support structure 302 of the second wheel subassembly 300b F has no wheels 303, which provides an opportunity to simplify the channel design inside the structure. The passage 305 can be provided in the large circumferential gap between the single wheel 303 in the front half H F and the adjacent wheels 303p or 303s on the port or starboard side. As described previously, the passage 305 can be large enough for a person to fully pass through, or small enough to only act as a conduit for cables, fluid pipes, or only as a hole for inserting monitoring devices such as cameras.

[0130] In the shown embodiment of the second wheel subassembly 300b, the spacing of the wheels 303 in the front half H F of the support structure 302 is large, such that the passage 305 is large enough to optionally include a ladder 305a, thereby making it easier for a person to pass through the support structure 302.

[0131] The first wheel subassembly 300a and the second wheel subassembly 300b described above can be used in combination with any of the previously described Magnus rotor examples or embodiments. That is, as mentioned, the support structure 302 of each of FIGS. 3(a) or 3(b) can be Figure 1(a) and 1(b)The bracket 105 of the exemplary Magnus rotor 100, or forms part of the bracket, and as previously described, the wheel 303 can be arranged to roll against the running surface 102a of the bearing ring 102 of such a Magnus rotor 100. It can also be understood that either the first wheel assembly 300a or the second wheel assembly 300b can also be used in combination with other Magnus rotor designs. For example, one or the other of the first wheel assembly 300(a) and the second wheel assembly 300(b) can be configured such that the wheel 303 runs directly against the wall of the rotor rather than against a bearing ring or other running surface (whose diameter is smaller than the rotor diameter).

[0132] Drive assembly

[0133] As previously mentioned, in some instances, one or more wheels can be used not only to transfer loads between the rotor and a support structure (such as a bracket), but also to drive the rotation of the rotor. Driving the rotation of the rotor through one or more wheels (e.g., through a lower drive assembly) has several advantages compared to driving the rotor through an upper bearing assembly. First, since the heavy drive assembly is located at a lower position, the weight of the resulting Magnus rotor is distributed at a lower position, thereby otherwise reducing the weight at a higher altitude of, for example, the upper bearing assembly such as a bracket or a tower. This way of distributing the weight downward provides a virtuous cycle regarding the total weight of the Magnus rotor; the smaller the weight at a higher altitude, the smaller the bending stress (due to inertial forces) at the bottom of the tower, and thus the less steel required for the tower (i.e., the support structure). Second, it simplifies equipment access. During the entire service life of the rotor, the drive assembly of the rotor may require a large amount of maintenance (and possibly component replacement). Therefore, it is clearly more advantageous to place the drive system at the lower part of the rotor because the components there are more accessible. Additionally, the requirements for gears are also reduced. A low-cost AC induction motor operates from typical ship power at a 60Hz frequency AC, with a maximum efficient rotational speed of approximately 1200 rpm, while the maximum rotational speed of a rotor with a diameter of 5m is approximately 200 rpm, and the rotational speed needs to be reduced by approximately 6 times. Although this can be achieved by using a gearbox, a belt drive, or a chain drive to drive the rotor through a shaft in the upper bearing assembly, doing so will result in power loss and heat generation, so this is not desirable. If instead one or more wheels in the wheel assembly are driven to form a drive assembly, the ratio between the rotor running surface and the wheel diameter can be arranged to be approximately 6, and thus no gears are required for movement. Finally, using multiple wheels as drive wheels in the drive assembly allows for distributed power transmission, alternative operating modes, and additional redundancy.

[0134] Figure 4Schematically shows an example of a drive assembly 400 for a Magnus rotor. The drive assembly 400 consists of a drive wheel mechanism 407 and a plurality of idler wheel mechanisms 408. The drive wheel mechanism 407 includes a drive wheel 403a that can be positioned to roll against the running surface 402a of the rotor and a drive mechanism 410 connected to the drive wheel 403a. The drive mechanism 410 can be configured to provide torque to drive the drive wheel 403a to rotate. The drive wheel 403a in turn transmits this drive torque to the running surface 402a of the rotor.

[0135] The drive wheel mechanism 407 further includes a biasing mechanism 409 that is configured to bias the drive wheel 403a towards the running surface 402a in use. More specifically, in the illustrated embodiment of the drive assembly 400, the biasing mechanism 409 is configured to increase the degree of biasing applied as the torque supplied by the drive mechanism 410 increases.

[0136] Each idler wheel mechanism 408 includes an idler wheel 403b. The idler wheel 403b is also configured to roll against the running surface 402a. However, the idler wheel 403b is freely rotatable, which means that the idler wheel can rotate about its respective wheel axis with minimal resistance or relative torque. Thus, in use, when the drive wheel 403a rotates the running surface 402a, the running surface 402a in turn rotates the idler wheel 403b.

[0137] In the illustrated embodiment, the drive wheel 403a includes an inflated tire 406a, and each idler wheel 403b includes a solid tire 406b. The drive wheel 403a requires a higher coefficient of friction or preloading to facilitate torque transfer to the running surface 402, but can be designed such that the maximum load it bears may be lower than the maximum load of the idler wheel 403b, which needs to withstand the thrust of the rotor in use. Compared with the solid tire 406b on the idler wheel 403b, the inflated tire 406a on the drive wheel 403a has a greater frictional force against the running surface 402a, while the solid tire 406b on the idler wheel is more durable and wear-resistant. In other words, the tires used for the two wheels 403a, 403b are optimal for their loading characteristics.

[0138] In the illustrated embodiment, the inflated tire 406a has a cylindrical profile (e.g., as shown by the wheel 203 Figure 2 ), and the shape of the inflated tire is set to maximize the effective contact area with the running surface 402a. The inflated tire 406a is preferably made of rubber or a material including rubber, but not necessarily so. As used herein, rubber refers to a synthetic rubber compound similar to automotive tires. In fact, automotive tires themselves can also be suitable for the drive wheel 403a.

[0139] The solid tire 406b can be formed of polyurethane and / or metal, or a material including polyurethane and / or metal. Tires containing polyurethane or metal tend to wear faster, but the traction against the running surface 402a may be lower. To minimize wear, the solid tire 406b preferably uses a polyurethane material with a Shore hardness of 70A or harder, or a metal material with a Brinell hardness of 100HB or harder.

[0140] In the illustrated example, the drive wheel 403a and the three idler wheels 403b are positioned to roll against the same running surface 402a. However, in other examples, one or more drive wheels can roll against one running surface, while one or more idler wheels can roll against a different running surface.

[0141] It will be appreciated that the wheel assembly 300 described with respect to FIG. 3 can be modified to include one or more drive wheels and the remaining number of idler wheels, as described above, in order to determine additional drive assemblies according to another embodiment of the present invention. More specifically, such additional drive assemblies will include a plurality of wheels spaced unevenly apart, where one or more of the wheels are drive wheels and the remaining wheels are idler wheels.

[0142] FIG. 5 shows an exemplary drive wheel mechanism 507 for Figure 4 the drive assembly 400 (or any other drive assembly, such as the additional drive assembly mentioned above). The drive wheel mechanism 507 consists of a drive wheel 503, a drive mechanism 510, and a biasing mechanism 509.

[0143] The drive wheel 503 is configured to roll against the running surface of the rotor. In the illustrated embodiment, the running surface 502a is the inner surface of a bearing ring 502 that is connected to and rotates with the rotor 501. The drive wheel 503 is mounted to an axle such that it rotates about a wheel axis 503a. The drive wheel 503 also includes an elastically compressible tire, such as an inflated tire.

[0144] The drive mechanism 510 can include an electric motor (such as an electric motor), a turbine, or other power systems. In some examples, the drive mechanism is the power source of a ship, and the drive torque is transmitted to the drive wheel through a dedicated drive shaft.

[0145] In the illustrated embodiment, the drive mechanism 510 provides torque to the drive wheel 503 through the biasing mechanism 509, and more specifically, through a drive shaft 510a connected to the axle.

[0146] Meanwhile, the biasing mechanism 509 includes a swing chassis in the form of a swing bracket 511, and the swing chassis is connected to the distal end of the axle through corresponding bearing members 511a. The swing bracket 511 is further pivotally connected to a pair of pivot brackets 512 located on either side of the swing bracket 511 along the driving wheel axis 503a. The pivot brackets 512 themselves are fixedly mounted to the support structure 505, which, as described herein, may be or include a bracket and / or a tower.

[0147] The biasing mechanism 509, i.e., the swing bracket 511 and the associated components, is arranged to pivot relative to the pivot brackets 512 about the pivot axis 512a. Since the driving wheel 503 is spaced apart from the pivot axis 512a, pivoting of the swing bracket 511 causes the driving wheel 503 to trace an arc 515 about the pivot axis 512a. The driving wheel 503, the swing bracket 511, and the pivot axis 512a are arranged relative to each other such that movement of the driving wheel 503 through the arc 515 changes the spacing between the wheel axis 503a and the running surface 502a. More specifically, when the swing bracket 511 is in the first position 515a relative to the pivot brackets 512, i.e., when the swing bracket 511 is aligned with the pivot brackets 512, the distance between the wheel axis 503a and the running surface 502a is the greatest, and as the swing bracket 511 pivots towards the second position 515b relative to the pivot brackets 512, the wheel axis 503a moves towards the running surface 502a, i.e., the spacing between the wheel axis 503a and the running surface 502a decreases.

[0148] As the torque supplied by the driving wheel 503 increases, the risk that the driving wheel 503 slips against the running surface 502a rather than rolls smoothly also increases. Slipping results in increased wear on both the driving wheel 503 and the running surface 502a, and inefficient torque transfer from the driving wheel 503 to the running surface 502a.

[0149] The biasing mechanism 509 can resolve this problem. In use, the torque supplied by the drive mechanism 510 causes the driving wheel 503 to rotate and apply a driving force 513 to the running surface 502a, causing the rotor to rotate. However, the running surface 502a also applies a reaction force 514 against the driving wheel 503, thereby causing the wheel to roll around the running surface 502a. The reaction force 514 ultimately acts on the swing bracket 511, causing the swing bracket to pivot relative to the pivot brackets 512, thereby causing the driving wheel 503 to move through the arc 515, and thus causing the wheel axis 503a to move closer to the running surface 502a, i.e., towards the second position 515b, and thereby pressing the driving wheel 503 into the running surface 502, which results in compression of the wheel tire.

[0150] As the torque increases, the driving force 513 also increases, and thus the reaction force 514 acting on the swing bracket 511 also increases, and the drive wheel 503 is pressed more strongly into the running surface 502a. In other words, the normal contact force between the drive wheel 503 and the running surface 502a increases, which increases the traction force of the drive wheel 503 on the running surface 502a, so that the drive wheel 503 can transmit a greater lateral force to the running surface 502a without slipping.

[0151] However, the higher normal contact force itself may cause increased wear of the drive wheel 503 and / or the running surface 502a, as well as an increase in the rolling resistance of the drive wheel 503 on the running surface 502a, which results in an increase in the energy required to rotate the rotor.

[0152] Therefore, it is desirable to be able to adjust, and in particular reduce, the normal contact force as needed. The biasing mechanism 509 is further configured to achieve this. More specifically, as the torque decreases, for example starting from the maximum desired level, the driving force 513 decreases, and thus the reaction force 514 acting on the swing bracket 511 also decreases. In this way, the elasticity (i.e., compressibility) of the wheel tire can overcome the force pressing the drive wheel 503 into the running surface 502a, and the expansion of the tire causes the swing bracket 511 to pivot in the opposite direction (returning towards the first position 515a), and thus, the traction force between the drive wheel 503 and the running surface 502a decreases.

[0153] Therefore, the biasing mechanism 509 can ensure that torque can be efficiently transferred from the drive wheel 503 to the running surface 502a at all speed and drive torque levels without slipping or excessive wear. In other words, the radial loading on the drive wheel 503 varies with the drive torque such that when the drive torque is low, the rolling resistance provided by the drive wheel 503 is minimized, but when the drive torque is high, the radial loading is large enough to generate sufficient friction to prevent the wheel from slipping.

[0154] In other examples, the biasing mechanism may include a servo or pneumatic actuator configured to move the wheel axis 503a relative to the running surface 502a. In one such example, the controller receives information about the drive torque level (e.g., from the drive mechanism 510 itself), and then provides an instruction to the servo to reduce the spacing between the wheel axis 503a and the running surface 502a.

[0155] In the illustrated embodiment, the drive wheel 503 includes a pair of pneumatic tires mounted parallel to the wheel axis 503a. In other examples, the drive wheel may be a single continuous tire having a cylindrical profile (e.g., as Figure 2as shown by the wheel 203), the shape of the drive wheel is set to maximize the effective contact area with the running surface. In some additional instances, the drive wheel can be made of rubber or a material including rubber. In fact, an automotive tire itself can also be applicable to the drive wheel in some instances.

[0156] The swing bracket 511 and the pivot bracket 512 can be constrained such that the swing bracket 511 cannot rotate more than 15 degrees without being misaligned with the pivot bracket 512. This can additionally help avoid wheel slippage between the drive wheel 503 and the running surface 502a.

[0157] Bias assembly

[0158] As previously discussed with respect to Figure 3(a) and 3(b) the first wheel assembly 300a and the second wheel assembly 300b can include a loading arrangement 307 that is configured to radially outwardly push the wheels. Alternatively or additionally, a biasing assembly, such as the first biasing assembly 604 shown in FIG. 6(b), can act as a suspension system for the wheels within such wheel assemblies 300a, 300b, for example to absorb and damp cyclic or transient forces between the rotor and the support structure.

[0159] Referring to FIG. 6(a), the Magnus rotor includes a rotor 601 and a support structure 602. In use, the support structure 602 is fixedly connected to a vessel such as a ship. The rotor 601 is coaxially arranged with the support structure 602, and a third wheel assembly 600a including a plurality of wheels 603 transfers the load between the running surface 601a of the rotor 601 and the support structure 602. The wheel assembly 600a and the running surface 601a can be considered together as forming at least a part of a lower bearing assembly.

[0160] In this instance, the running surface 601a is the inner surface of the rotor 601. In other instances, the running surface can be the inner surface of a bearing ring as described above, or even the outer surface of a bearing ring as mentioned above.

[0161] In use, when an external load 606 is applied to one side of the rotor 601 (e.g., a gust of wind), the asymmetric loading of the rotor 601 causes an increase in the load on the wheels 603 proximal to the point of application of the external load 606 and a decrease in the load on the wheels 603' distal to the point of application of the external load 606.

[0162] From here on, it can be understood that the prime symbol used with reference numerals (e.g., 603') represents a specific reference to a feature when in use and distal to the point of application of the external load 606.

[0163] Wheels configured only to prevent rotor deflection upon application of an external load may create cyclic or transient forces between the rotor and the support structure, which may cause failure of the associated Magnus rotor. Accordingly, it is desirable to include a biasing assembly, such as the first biasing assembly 604 according to an embodiment of the present invention, in the Magnus rotor to absorb and dampen such cyclic or transient forces. Accordingly, each wheel 603 in the Magnus rotor shown in FIG. 6(a) is connected to the support structure 602 by such first biasing assembly 604.

[0164] The first biasing assembly 604 allows the wheel 603 and the rotor 601 proximal to the external load 606 to deflect away from the direction of the load 606. However, when the wheel 603 is loaded (and deflected) on one side of the support structure 602, the wheel 603' on the other side of the support structure 602, i.e., the wheel away from the load 606, unloads (and deflects) by the same distance.

[0165] Advantageously, all the wheels 603 are held in contact with the running surface 601a with sufficient force such that no slip occurs between any of the wheels 603 and the rotor 601 under all operating conditions to prevent rapid wear. Accordingly, it is desirable that each biasing assembly 604 applies a preload to its wheel 603 such that even when the rotor 601 is offset from the support structure 602, the wheel 603' loaded on the far side will maintain contact with the running surface 601a. In other words, it is desirable that each biasing assembly 604 be configured such that a biasing force is applied to urge the wheel 603 against the running surface 601a even in the absence of any other external forces on the rotor 601.

[0166] However, if each biasing assembly 604 is to produce a constant force characteristic (e.g., where the biasing member is a rigid elastic spring that follows Hooke's Law), for four wheels 603, the preload on each wheel 603 must be at least half of the maximum operating load of the rotor (i.e., the maximum expected value of the asymmetric force 606), which means that the total preload is twice the maximum operating load. However, this arrangement is less efficient because the rolling resistance is approximately proportional to the radial force on the wheel 603.

[0167] To address this issue, the biasing assembly 604 includes a pair of biasing members 605, each of which alternatively exhibits a non-constant force characteristic, thereby decoupling the two functions of carrying the load on the loaded side of the rotor 601 and maintaining contact on the unloaded side. Other embodiments (not shown) may include fewer or more than two biasing members 605.

[0168] Each biasing member 605 includes a first coupling 604a that can be connected to the support structure 602. The first coupling 604a is connectable in the sense that the biasing member 605 can be selectively detached from the support structure 602 (e.g., for maintenance or replacement). Each biasing member 605 also includes a second coupling 604b that can be connected to the wheel 603 such that each wheel 603 can rotate about a wheel axis 603a relative to the corresponding biasing member 605. In the illustrated example, the first coupling 604a takes the form of a mounting bracket that couples a given biasing member 605 to the support structure 602; and the second coupling 604b takes the form of a wheel bearing that supports the axle about which the wheel 603 rotates. In other examples, the first and second couplings can take different forms as long as they interconnect the biasing member between the support structure and the wheel axle.

[0169] A corresponding pair of biasing members 605 are configured to radially outwardly r push the corresponding wheel 603 towards the running surface 601a, in the sense that the biasing member 605 provides a biasing force that radially outwardly pushes the wheel 603 towards the running surface 601a.

[0170] More specifically, when the wheel axis 603a is in a first displacement region, the biasing member 605 pushes the wheel 603 towards the running surface 601a according to a first force characteristic; and when the wheel axis 603a is in a second displacement region, the biasing member pushes the wheel 603 towards the running surface 601a according to a second different force characteristic.

[0171] For example, if the biasing member 605 includes a spring, then the force characteristic can be the stiffness of the spring.

[0172] In the illustrated embodiment, each biasing member 605 includes a first biasing element 605d and a second biasing element 605e. The first biasing element 605d and the second biasing element 605e have different force characteristics, and more specifically the first biasing element 605d has a first force characteristic and the second biasing element 605e has a second force characteristic, where the first force characteristic results in a lower degree of biasing applied compared to the result of the second force characteristic. Thus, the first biasing element 605d provides a lower degree of biasing compared to the second biasing element 605e.

[0173] Figure 7FIG. 700 shows the biasing force F versus the displacement x, which corresponds to the force characteristics provided by each of the biasing members 605 described above. The displacement x is the displacement of the wheel axis 603a relative to the transition point 703 in the direction r shown in FIG. 6(b). Here, a positive displacement x represents the displacement of the wheel axis 603a in the direction of the running surface (away from the rotor axis 601b in this example), while a negative displacement -x represents the displacement of the wheel axis 603a in the opposite direction of the running surface (towards the rotor axis 601b in this example).

[0174] The transition point 703 represents the point at which the first displacement region 704 transitions to the second displacement region 705. As mentioned above, when the wheel axis 603a is in the first displacement region 704, each non-linear biasing member 605 pushes the wheel 603 towards the running surface 601a according to the first force characteristic 701, which is provided by the first biasing element 605d and represented by the gradient of the first force characteristic 701. At the same time, when the wheel axis 603a is in the second displacement region 705, each non-linear biasing member 605 pushes the wheel 603 towards the running surface 601a according to the second force characteristic 702, which is provided by the second biasing element 605e and represented by the gradient of the second force characteristic 702.

[0175] When installed for use, each biasing assembly 604 can be configured such that when the rotor 601 is not experiencing an external load 606 (which would otherwise cause the running surface 601a to deflect), the wheel axis 603a is at the transition point 703. In some instances, each biasing member is adjustable to change the transition point and apply a preload to one or both of the biasing elements. In still other instances, the biasing element itself includes an adjustment mechanism that can independently adjust its preload level.

[0176] Thus, during use, when there is no effective external load on a particular biasing assembly 604, the biasing force F provided by the corresponding biasing member 605 is the biasing force associated with the transition point 703. As shown in FIG. 700 of Figure 7 , the biasing force F at the transition point 703 is generated entirely or almost entirely according to the first force characteristic 701, i.e., by the first biasing element 605d of each biasing element 605 due to the preload applied to the first biasing element 605d. The second biasing element 605e may provide little or no biasing force F. Additionally, at the transition point 703, a given biasing member 605 is preferably configured such that the first biasing element 605d provides its maximum biasing force F, which makes it unlikely that the first biasing element 605d will provide additional biasing force F. For example, this can be achieved by a mechanical stop.

[0177] When an external load 606 is applied to the rotor 601, the external load travels through the running surface 601a to the wheel 603 proximal to the applied load 606, and then to the corresponding biasing assembly 604. In response to the increased load, the biasing member 605 of the biasing assembly 604 counteracts the load with an increased biasing force F, because as the wheel 603 deflects inwards (towards the rotor axis 601b), the wheel axis 603a moves to the second displacement region 705, and the biasing member 605 then pushes the wheel 603 towards the running surface according to the second force characteristic 702 of the second biasing element 605e.

[0178] The wheel 603 proximal to the applied load 606 deflects inwards such that the running surface 601a distal to the applied load 606 deflects outwards (as shown on the left side of Fig. 6(a)). This reduces the load applied to the wheel 603' distal to the applied load 606, and thus reduces the load on the corresponding biasing assembly 604'. As the load to be counteracted decreases, the biasing force F generated by the biasing member 605' of the biasing assembly 604' also decreases as the preload of the first biasing element 605d' is expelled. In other words, when the wheel axis 603a' of the wheel 603' distal to the load moves into the first displacement region 704, the corresponding biasing member 605' pushes the wheel 603' towards the running surface 601a according to the reduced first force characteristic 701 provided by the corresponding first biasing element 605d'.

[0179] The first biasing element 605d can be or include a helical spring, a leaf spring, a pneumatic actuator, and / or a hydraulic actuator (or other types of fluid actuators). Such assemblies can be designed with end stops and such that they have a low effective stiffness before reaching the end stop displacement (at the transition point 703). The force characteristic selected for the first biasing element can be a compromise between different requirements. As discussed, the force to keep the wheel 603 in contact with the running surface 601a should be as small as possible while maintaining sufficient grip force to keep the wheel 603 rotating. Therefore, the effective stiffness should be much lower than the effective stiffness of the second biasing element 605e such that when the second biasing element 605e deflects, the opposing wheel 603' (i.e., the wheel on the other side of the support structure) does not lose too much contact force due to the extension of its first biasing element 605d from the initial preloaded position. In other words, the first biasing element should be selected or configured such that the first force characteristic 701 has a shallower gradient on the graph 700.

[0180] However, if the effective stiffness of the first biasing element 605d is too low (or if the preload comes from gravity or, for example, from a pneumatic or hydraulic actuator with an accumulator, the effective stiffness is zero), then its dynamic behavior may become unpredictable.

[0181] The second biasing element 605e can be or include an elastomeric block, optionally formed of or including an elastomeric material. An elastomeric block, such as a solid rubber block, can have a higher effective stiffness than any actuator or spring. The force characteristics selected for the second biasing element 605e can also be a compromise. The second biasing element 605e should preferably have sufficient stiffness so as to be able to adequately resist the maximum loading without allowing the rotor 601 to hit the support structure 602, but not so effectively stiff that it causes an unduly high cyclic loading on the wheel 603 or the biasing assembly 604 due to the runout (non-circularity) of the wheel 603 or the running surface 601a. For example, if the effective stiffness of the second biasing element 605e is 10 kN / mm, a 2 mm runout (non-circularity) on the running surface 601a will produce a 20 kN cyclic loading, which repeats every revolution. Since the rotor will operate continuously for most of its service life, this can add a large number of stress cycles.

[0182] The effective stiffness of the second biasing element 605e can be selected such that it is stiff enough to prevent the rotor 601a from undergoing resonant oscillations within the desired operating speed range. A biasing assembly 604 with a low effective stiffness can cause the rotor to resonate due to a small imbalance of the rotor within the operating speed range. This situation is undesirable because it may cause the rotor to have to avoid a portion of the operating speed range of the rotor, thereby truncating the operating speed range of the rotor. When the rotor passes through the speed range of said portion, wear / fatigue will increase. For example, on a 5 m x 35 m rotor 601, the rotor mass may be around 20 metric tons, the effective moving mass on the lower bearing assembly is approximately 10 metric tons, and the maximum operating speed is 180 rpm. Thus, an estimate of the minimum stiffness required to keep the resonance mode outside the operating range can be calculated by the following equation:

[0183]

[0184] Thus, for a typical 5 m x 35 m rotor 601, the second force characteristic 702 of the biasing member 605 in each biasing assembly 604 should indicate that the effective stiffness of the rotor should be significantly greater than 4 kN / mm. To avoid resonance, in some instances, the second force characteristic should indicate an effective stiffness on the rotor that is at least twice the product of the rotor moving mass and the square of the desired maximum operating angular velocity of the rotor. In some instances, the effective stiffness is 1 to 4 times the minimum stiffness required to prevent resonant rigid body vibrations of the rotor within the operating speed range.

[0185] Figure 8An example of a second biasing assembly 804 according to another embodiment of the present invention is shown, and a corresponding biasing assembly 805 within the second biasing assembly 804 is shown in particular more detail. The biasing member 805 is coupled to a support structure (not shown) by a first coupling 804a and to a wheel 803 by a second coupling 804b, and thus the second biasing assembly 804 is fully interchangeable with the first biasing assembly 604 described above.

[0186] The biasing member 805 shown includes a first biasing element 805d and a second biasing element 805e. More specifically, the first biasing element 805d includes a helical spring, and the second biasing element 805e includes a pair of elastic blocks, each formed of a solid elastic material.

[0187] The second coupling 804b is connected to the second biasing element 805e, which is in series with a plate 810. At the same time, the first coupling 804a is connected to a rod 811 that extends from the first coupling 804a through the two elastic blocks of the second coupling 804b and the second biasing element 805e and through the plate 810. Attached to the rod 811 is a transition nut 812. The transition nut 812 is threaded onto the rod 811 and is movable along the rod, but only by applying sufficient torsional force. Thus, the transition nut 812 can be rotated by an operator (such as an installer of the second biasing assembly 804) along the rod 811 to a given position and then fixed in that position until another torsional force is applied.

[0188] Thus, the rod 811 is anchored to the support structure by the first coupling 804a, and the transition nut 812 can be fixed at a certain distance from the first coupling 804a (and the support structure). On the other hand, the second coupling 804b, the second biasing element 805e, and the plate 810 are movable freely along the rod 811, and this movement facilitates the movement of the wheel 803 relative to the support structure. However, the plate 810 is configured to abut against the transition nut 812, which means that any additional movement of the wheel 803 towards the rotor axis (i.e., in the -r direction) requires compressing the elastic blocks of the second biasing element 805e.

[0189] As Figure 8As can be seen, the rod 811 extends beyond the transition nut 812 and passes through the helical spring of the first biasing element 805d to reach the preload nut 813. The preload nut 813 is similar to the transition nut 812 and can be rotated along the rod 811 to a given position and then fixed in that position such that, in use, its distance from the first coupling 804a and the support structure is fixed. To enable the first biasing element 805d to exert a force on the wheel 803, a shelf 814 is installed at a fixed distance from the plate 810. The shelf 814 provides a surface for the helical spring to exert a force while bypassing the obstacle otherwise created by the transition nut 812. When the rotor deviates from the rotor axis, the load acting on the first biasing element 605d will decrease and the helical spring will extend such that the shelf 814 and the plate 810 move radially outwards (in the direction r) away from the transition nut 812. This in turn causes the wheel 803 to move radially outwards (in the direction r), thereby maintaining rolling contact between the wheel and the associated running surface of the rotor.

[0190] It can be noted that the second biasing element 805e can be chosen to be stiff enough so as not to compress (or compress negligibly) in response to the load applied to it by the first biasing element 805d, thus ensuring that when the wheel axis ( Figure 8 not shown in the figure) is in the first displacement region 704 (i.e., as Figure 7 shown), only the first biasing element 805d is operative.

[0191] During installation, the biasing member 805 can be configured to make the desired setting by appropriately positioning the transition nut 812 and the preload nut 813. First, the transition nut 812 is positioned such that when the rotor rotates under normal conditions (i.e., without an external load acting to deflect the rotor), as the wheel 803 rolls against the running surface of the rotor, the position of the wheel will cause the plate 810 to abut against the preload nut 813 but not compress the second biasing element 805e. Thus, in response to an external load causing the rotor to deflect in the opposite direction, the resilient block will start to push the wheel 803 away from the rotor axis (in the direction r). In other words, this positioning of the transition nut 812 sets the transition point 703 (as Figure 7 shown) at which, in addition to the first biasing element 805d, the second biasing element 805e also starts to act on the wheel.

[0192] Secondly, the preloading nut 813 is positioned such that the first biasing element 805d is sufficiently compressed to provide sufficient preloading. Sufficient preloading ensures that sufficient force is exerted by the first biasing element 805d to push the wheel 803 away from the rotor axis (in the direction r), such that even if the rotor is offset from the wheel 803, the wheel still maintains rolling contact with the running surface. Thus, sufficient preloading can be set such that the first biasing element 805d still has sufficient loading to keep the wheel 803 in rolling contact with the running surface when the rotor is deflected in the direction r by the maximum expected amount. However, as mentioned above, when the rotor rotates under normal conditions (i.e., in the absence of external loading), it is desirable that the loading exerted by the first biasing element 805d is not excessive, and this can be achieved by selecting the first biasing element (e.g., the stiffness of the helical spring).

[0193] Swivel wheel mechanism

[0194] Another cause of excessive wear of the Magnus rotor is the deformation of the components under loading. Figure 9(a) shows Figure 1(a) and 1(b) a simplified version of the Magnus rotor 100, where the rotor 101 engages with the bracket 105 through the upper bearing assembly 107 and is configured to rotate around the bracket 105. The wheel assembly includes the plurality of wheels 103, each of which contacts a running surface 102a on a bearing ring 102 that runs on the inner surface of the rotor 101. As shown in Figure 9(b), each wheel 103 is mounted relative to the bracket 105 such that the wheel can rotate about the wheel axis 103a, which shows an enlarged view of one such wheel 103. The wheel 103 is substantially cylindrical, as previously discussed, which can maximize its contact area with the running surface 102a.

[0195] In use, when a load 901 is applied by the rotor 101 to the bracket 105, this may cause the bracket 105 to bend in the direction of the applied load 901. This in turn causes the rotor 101 to tilt relative to the deck 106, and in use, the bracket 105 is fixed to the deck, because the upper bearing assembly 107 connected to the top of the bracket 105 is displaced. Thus, the wheel axle 103a of one or more of the wheels 103 may be misaligned with the running surface 102a, as best shown in Figure 9(a). Thus, instead of contacting the running surface 102a along its entire height, the misaligned wheel or each misaligned wheel contacts the running surface 102a only along the edge or a smaller contact area. This increases the local contact stress and asymmetric loading of such misaligned wheels 103 with the running surface 102a, thereby accelerating their corresponding wear rate.

[0196] For clarity, the degree of bending and displacement in FIGS. (a) and 9(b) is exaggerated. However, it will be understood that even a small degree of bending and displacement can cause misalignment between the wheel axis 103a and the running surface 102a of the bearing ring 102. Additionally, manufacturing defects and tolerances in components such as the running surface 102a, the carriage 105, and / or the wheel 103 can cause one or more wheel axes 103a to be misaligned with the running surface 102a.

[0197] Accordingly, Figure 10 and 11 there are shown a first caster mechanism 1000 and a second caster mechanism 1100 for a Magnus rotor, which are configured to eliminate such wheel misalignment. The first caster mechanism 1000 and the second caster mechanism 1100 each include mounting assemblies 1001, 1101, which rotatably support the wheels 1003 in use relative to a support structure (not shown) 1103 by means of bearing members such that each wheel 1003, 1103 can rotate relative to the mounting assemblies 1001, 1101 about corresponding wheel axes 1003a, 1103a. Each wheel 1003, 1103 is configured to run relative to a corresponding running surface 1002a, 1102a of the rotor. The two rotors themselves are not shown except for their respective axes of rotation 1002, 1102. As previously described, the running surfaces 1002a, 1102a can be the inner or outer surface of a bearing ring connected to the inner wall of the rotor, or can be the wall of the rotor itself.

[0198] In any case, in each case, the wheel axes 1003a, 1103a and the rotor axes 1002, 1102 lie in a common radial plane. For example, in Figure 10 and 11 both the wheel axes 1003a, 1103a and the rotor axes 1002, 1102 lie in the plane of the figure itself, and thus such a plane defines a common radial plane. The radial plane can additionally be aligned with the radius or diameter of the rotor or the carriage (since the rotor can be arranged to rotate coaxially about the carriage).

[0199] Each mounting assembly 1001, 1101 includes a universal support, which allows the wheel axes 1003a, 1103a to pivot about corresponding universal axes 1007, 1107 such that each wheel axis 1003a, 1103a remains aligned with the corresponding running surface 1002a, 1102a of the rotor. Each universal axis 1007, 1107 is perpendicular to the corresponding wheel axis 1003a, 1107a and perpendicular to the corresponding rotor axis 1002, 1102 and the corresponding radial plane common to the corresponding wheel axes 1003a, 1103a. In other words, each universal axis 1007, 1107 extends normally toFigure 10 and 11 the plane of itself.

[0200] As mentioned, each wheel 1003, 1103 is substantially cylindrical, with a diameter D and an axial height H (e.g., as shown for a similar wheel 203 with respect to Figure 2 where the height H is measured along the direction of the wheel axes 1003a, 1103a). The axial height H is preferably at least 50% of the wheel diameter to reduce the contact stress within the wheels 1003, 1103, but this is not necessarily the case in practice.

[0201] In any case, when each wheel 1003, 1103 and the corresponding running surfaces 1002a, 1102a are correctly aligned, i.e., as shown in each figure of Figure 10 and 11 the contact surfaces between the wheels 1003, 1103 and the running surfaces 1002a, 1202a can be approximated as lines extending along the running surfaces 1002a, 1102a that are parallel and coplanar with the wheel axes 1003a, 1103a. Each such contact surface can be referred to as a contact line 1009, 1109. Additionally, in the illustrated embodiment, the length of each contact line 1009, 1109 is substantially equal to the height H of the wheels 1003, 1103 (i.e., as defined with respect to Figure 2 ). Each cylindrical wheel 1003, 1103 is symmetric about a plane perpendicular to the wheel axes 1003a, 1103a and passes through the midpoints 1009a, 1109a of the corresponding contact lines 1009, 1109.

[0202] Since the loading forces between each wheel 1003, 1103 and the corresponding running surfaces 1002a, 1102a are mainly (a) loading forces perpendicular to the contact lines 1009, 1109 or (b) axial frictional forces coplanar with the contact lines 1009, 1109, such loading forces can all be considered to act through the corresponding midpoints, such that each midpoint can be referred to as the corresponding center of action 1009a, 1109a.

[0203] In Figure 10 the first caster mechanism 1000 of, the caster axis 1007 is arranged to pass through the center of gravity 1006 of the wheel 1003, which helps to minimize the complexity of the corresponding first mounting assembly 1001, which can take the form of a relatively simple mounting bracket defining a caster support.

[0204] However, when the universal axis 1007 passes through the center of gravity 1006, any misalignment between the wheel axis 1003a and the rotor axis 1002 may cause the wheel 1003 to "tip" about the universal axis 1007 (i.e., the wheel is subjected to an overturning moment). This is because if the rolling direction of the wheel 1003 is not exactly the same as the movement direction of the running surface 1002a, a slip speed will be generated in the axial direction of the wheel 1003, thereby generating frictional force. This slip speed is a function of the misalignment; for example, if the wheel axis 1003a and the rotor axis 1002 are misaligned by 1° and travel at a linear speed of 25 meters per second, the slip speed is 25 * sin(1) = 0.4 meters per second. This may cause the wheel 1003 to tilt about the universal axis 1007, resulting in uneven contact pressure along the line contact 1009 of the wheel and accelerating wear at one edge of the wheel.

[0205] To help alleviate this problem, Figure 11 the second caster mechanism 1100 includes a universal axis 1107, which is alternatively configured to approximately extend through the center of the acting force 1109a, that is, directly through or substantially close to the center of the acting force 1109a, rather than the center of gravity 1106 of the wheel 1103.

[0206] In addition, to enable the wheel axis 1103a to pivot about the gimbal axis 1107, the second gimbal wheel mechanism 1100 includes a second mounting assembly 1101 which, in use, is pivotally coupled to a bracket, tower or other support structure via a gimbal support in the form of an angled link 1104 and an associated first mounting leg 1105, although other types of gimbal supports may also be used. More specifically, a first pivot point 1104a at one end of the angled link connects the angled link 1104 to the mounting assembly 1101, and a second pivot point 1104b at the second end connects the angled link 1104 to the mounting leg 1105 which, in turn, may be fixed to a bracket, tower or other support structure. Thus, the wheel axis 1103a can be considered to be pivotable relative to a bracket, tower or other support structure about the gimbal axis 1107. The gimbal support axis 1112 extends through the first pivot point 1104a and the second pivot point 1104b, assuming the two pivot members are frictionless, such that the angled link 1104 can only transmit force between the mounting leg 1105 and the mounting assembly 1101 along the gimbal support axis 1112. This force may be referred to as the gimbal support force. The pivot members 1104a, 1104b and the angled link 1104 are arranged such that the gimbal support axis 1112 substantially coincides with the center of the applied force 1109a. That is, the gimbal support axis 1112 passes through or close to the center of the applied force 1109a such that the gimbal support force is substantially directed towards the center of the applied force 1109a. This helps to ensure that the gimbal support force does not create a rotational torque about the center of the applied force 1109a which would otherwise cause one edge of the wheel 1103 to press more forcefully into the running surface 1102a than the other and thereby increase wear.

[0207] In the illustrated embodiment, the second mounting assembly 1101 is additionally coupled to a bracket, tower or other support structure in use via a biasing support in the form of a biasing member 1108 and an associated second mounting leg 1105, although other forms of biasing supports may also be used.

[0208] Similar to the angled link 1104, one end of the offset member 1108 is pivotally connected to the second mounting assembly 1101 and the other end is pivotally connected to the mounting leg 1110 which in turn may be fixed to a bracket, tower or other support structure. The arrangement of the gimbal axis 1107 passing through the center of force 1109a, and similarly the gimbal support force acting along the gimbal support member axis 1112 and through the center of force 1109a, the weight of the wheel 1103 (i.e., acting through its center of gravity 1106) and the weight of the mounting assembly 1101 (i.e., the total weight of the second swivel wheel mechanism 1100) all tend to create an overturning moment about the gimbal axis 1107. If not counteracted, this moment (i.e., rotational force) will cause misalignment of the wheel axis 1103a and the rotor axis 1102, resulting in uneven and / or excessive wear on one edge of the wheel axis 1103. However, the offset member 1108 is arranged to provide an offset force 1111 (or in other instances, an offset torque) to counteract the rotational force generated by the weight of the wheel 1103 and the mounting assembly 1101 (i.e., the total weight of the second swivel wheel mechanism 1100). The offset force 1111 is also used to push the wheel 1103 outward against the running surface 1102a, which helps to keep the wheel 1103 and the running surface 1102a in constant contact. The offset member 1108 may comprise a spring as shown or another actuator such as a fluid piston or an elastic member. In other instances, the offset member may comprise a balance weight positioned to counteract the weight forces from the wheel 1103 and the mounting assembly 1101.

[0209] In some instances, the second mounting assembly may be coupled to a support structure of a certain description by a plurality of angled link arms 1104, the first pivot members of the link arms being arranged along a mutual first axis and the second pivot members being arranged along a mutual second axis. By dispersing the loading forces through the plurality of link arms 1104, the stress and bending moment on each link arm 1104 can be reduced.

[0210] Additional examples

[0211] It is contemplated that any two or more instances or embodiments of the present invention described above may be combined together for use with a single Magnus rotor.

[0212] In one instance, the Magnus rotor 100 ( Figure 1(a) and 1(b)) can be easily modified to include the first wheel assembly 300a (Figure 3(a)) or the second wheel assembly 300b (Figure 3(b)). One compromise in the configuration of the Magnus rotor 100 is that reducing the size of the running surface 102a (i.e., reducing the diameter) results in the wheels 103 being arranged closer together compared to the wheel arrangement when the running surface is larger, and the former case may thus reduce the available space within the tower 105a. By adopting a non-uniform spacing of the wheels according to the expected loading envisioned in each of the first wheel assembly 300a and the second wheel assembly 300b, i.e., by removing potentially redundant wheels and thereby providing more space within the tower 105a, this compromise can be negated.

[0213] In another example, the Magnus rotor 100 ( Figure 1(a) and 1(b) ) can also be easily modified to include Figure 4 the drive assembly 400. That is, one or more of the wheels 103 in the Magnus rotor 100 can be configured as drive wheels 403a, and one or more of the remaining wheels 103 can be configured as idler wheels 403b. As previously described, it may be advantageous to drive the rotor rotation through the wheels 103 rather than through the upper bearing assembly 107. Since both the drive wheels and the idler wheels run against the common running surface 102a, it may be advantageous to use a first tire composition for the drive wheels and a second tire composition for the idler wheels in order to minimize rolling friction while avoiding slipping. In additional examples, the Magnus rotor 100 can be modified to include one or more drive wheel mechanisms 507, as shown in Figure 5. Such a drive wheel mechanism 507 will advantageously ensure that any wheel 103 that will become the drive wheel 403a remains in contact with the running surface 102a when the driving force 513 applied by the drive wheel 403a increases, thereby further reducing wear caused by slipping.

[0214] In still another example, the Magnus rotor 100 ( Figure 1(a) and 1(b) ) can be easily modified to include one or more biasing assemblies 604, as Figure 6(a) 、 6(b) shown. That is, one or more of the wheels 103 in the Magnus rotor 100 can be connected to the carriage 105 or the tower 105a through such a biasing assembly 604, whereby when the rotor 101 deflects relative to the carriage 105, the biasing assembly 604 or each biasing assembly reduces wear by absorbing resonance oscillations within the operating speed range of the Magnus rotor and ensuring that the corresponding wheels 103 remain in contact with the running surface 102a.

[0215] In yet another example, the Magnus rotor 100 (Figure 1(a) and 1(b) ) can be easily modified to include one or both of the first caster assembly 1000( Figure 10 ) and the second caster assembly 1100( Figure 11 ). That is, one or more wheels 103 of the Magnus rotor 100 can be connected to the carriage 105 or the tower 105a by one or the other of the first caster assembly 1000 and the second caster assembly 1100. Such first caster assembly 1000 and second caster assembly 1100 will reduce wear of the wheel 103 or each wheel so connected to the running surface 102a by keeping the wheel 103 aligned with the running surface 102a when the rotor 101 and the carriage 105 deform relative to each other under the application of a load.

[0216] In some additional instances, each of the first wheel assembly 300a and the second wheel assembly 300b( Figure 3(a) and 3(b) ) can include Figure 4 a drive assembly 400 therein. That is, one or more wheels 303 in the first wheel assembly 300a or the second wheel assembly 300b can be configured as drive wheels 403a, and one or more of the remaining wheels can be configured as idler wheels 403b. Considering the non-uniform radial loading of the rotor in use, the position of the drive wheel 403b or each drive wheel can be selected to maximize the torque transmission efficiency. For example, the port wheel 303p and the starboard wheel 303s in the second wheel assembly 300b of FIG. 3(b) can be configured as drive wheels 403a. In some instances, the first wheel assembly 300a and the second wheel assembly 300b can utilize Figure 6(a) and 6(b) a biasing assembly 604 therein to connect the wheels 303 configured as idler wheels 403b to the support structure 302 in use. Such modified first wheel assembly 300a or second wheel assembly 300b can be provided for retrofitting an existing Magnus rotor 100.

[0217] In other instances, Figure 6(a) and 6(b) the biasing assembly 604 therein can be easily modified to include the first caster assembly 1000( Figure 10 ) or the second caster assembly 1100( Figure 11), or vice versa. In other words, a single assembly is configured to radially outwardly push the wheel, absorb uneven radial loading, and also allow the wheel to deflect to remain aligned with the running surface during use. Providing this functionality in a single assembly facilitates installation compared to providing separate biasing assemblies 604 and first caster assemblies 1000 or second caster assemblies 1100 for a given wheel.

[0218] In a final example, the Magnus rotor 100( Figure 1(a) and 1(b) ) can be easily retrofitted to include a first wheel assembly 300a (FIG. 3(a)), and thus additionally benefit from the advantages of non-uniform wheel spacing. Further, such a first wheel assembly 300(a) can be easily retrofitted to include a drive wheel mechanism 507 (FIG. 5(a)), and thus additionally provide the advantages of a drive wheel 503 having a tire composition and torque-related biasing mechanism different from that of an idler wheel.

[0219] While such a drive wheel 503 benefits from a torque-related biasing mechanism, Figure 4 each of the idler wheels 403b Figure 6(a) and 6(b) The biasing assembly 604 is coupled to the carriage 105 in FIG. 1(a), and thus benefits from displacement-related biasing away from the rotor axis 101a.

[0220] In addition, one or more of the drive wheel 503 and the idler wheels 403b can be mounted to the carriage 105 using a first caster mechanism 1000( Figure 10 ) to maintain alignment of the drive wheels 503, 403b with the running surface 102a (FIG. 1).

Claims

1. A Magnus rotor, comprising: a rotor rotatable about a rotor axis, wherein an outer surface of the rotor defines a rotor diameter and an inner running surface of the rotor defines a running surface diameter no greater than 80% of the rotor diameter; a support structure configured to rotatably support the rotor; as well as A plurality of wheels are each rotatably mounted to the support structure for rotation about a respective wheel axis extending substantially parallel to the rotor axis and positioned so that the wheels roll against the inner running surface as the rotor rotates about the support structure.

2. A Magnus rotor according to claim 1, wherein the running surface diameter is no more than 70% of the rotor diameter; preferably no more than 60% of the rotor diameter.

3. A Magnus rotor according to any preceding claim, wherein the outer surface of each wheel defines a wheel diameter which is at least 10% of the diameter of the rotor.

4. The Magnus rotor according to claim 1, wherein: The plurality of wheels are spaced apart from one another about a pitch circle such that each wheel axis extends through the pitch circle; and The pitch circle defines a pitch circle diameter that is no greater than 70% of the rotor diameter; preferably no greater than 50% of the rotor diameter.

5. A Magnus rotor according to any one of the preceding claims, wherein: The support structure comprises a hollow tower having a wall having a substantially circular cross-sectional shape; and At least one wheel of the plurality of wheels is at least partially located within an outer diameter of the tower.

6. A Magnus rotor according to claim 5, wherein one or more of the wheels which are located at least partially within the outer diameter of the tower are positioned so that a majority of the or each wheel is located within the outer diameter of the tower.

7. A Magnus rotor according to any one of the preceding claims, wherein the rotor further comprises: a bearing ring, the inner surface or the outer surface of the bearing ring being the running surface of the rotor; as well as A radial flange is configured in an annular shape, wherein an inner edge is connected to an outer surface of the bearing ring, and an outer edge is connected to an inner surface of the rotor.

8. A Magnus rotor according to claim 7, wherein the radial flange comprises a passage.

9. A Magnus rotor according to any one of the preceding claims, wherein the axial height of at least one wheel is at least 50% of the diameter of the wheel.

10. A Magnus rotor according to any preceding claim, wherein at least one wheel comprises a substantially cylindrical outer surface.

11. A Magnus rotor according to any one of the preceding claims, wherein at least one wheel comprises a solid tyre; preferably a solid tyre comprising polyurethane or a fully polyurethane solid tyre.

12. A wheel assembly for a Magnus rotor, the wheel assembly comprising: Support structures; and A plurality of wheels are mounted to the support structure so as to be unevenly spaced from one another, each wheel being rotatable in use to roll against a running surface of the rotor as the rotor rotates.

13. The wheel assembly of claim 12, wherein each wheel of the plurality of wheels has at least one of the following: a height substantially the same as a height of each other wheel of the plurality of wheels; a diameter that is substantially the same as a diameter of each other wheel in the plurality of wheels; a weight that is substantially the same as the weight of each other wheel of the plurality of wheels; as well as A material composition that is substantially the same as the material composition of each other wheel in the plurality of wheels.

14. A wheel assembly according to claim 12 or claim 13, having: a rear half oriented, in use, towards the stern of the vessel; and A forward half is oriented towards the bow of the vessel in use and includes a fewer number of wheels than the rear half.

15. The wheel assembly of claim 14, wherein the front half has a front wheel density defined by the number of wheels of each support structure in the front half, the rear half has a rear wheel density defined by the number of wheels of each support structure in the rear half, and the front wheel density is no greater than 75% of the rear wheel density.

16. The wheel assembly of claim 15, wherein the front wheel density is no greater than 67% of the rear wheel density.

17. A wheel assembly according to any one of claims 14 to 16, wherein the front half comprises a passage located between two adjacent wheels.

18. A wheel assembly according to any one of claims 12 to 17, wherein: The support structure comprises a plurality of stowage arrangements, each configured to propel a respective wheel towards the running surface in use; and At least one loading arrangement urges the corresponding wheel toward the running surface according to a first loading characteristic, and at least another loading arrangement urges the corresponding wheel toward the running surface according to a second, different loading characteristic.

19. A wheel assembly according to claim 18 when dependent on claim 14 or any claim dependent therefrom, wherein: The first loading characteristic results in a lower degree of applied bias than the second loading characteristic; and at least one loading arrangement in the rear half is configured to push the corresponding wheel according to the first loading characteristic, and At least one loading arrangement in the front half is configured to push the corresponding wheel according to the second loading characteristic.

20. The wheel assembly of claim 19, wherein each loading arrangement in the rear half is configured to push the corresponding wheel according to the first loading characteristic, and each loading arrangement in the front half is configured to push the corresponding wheel according to the second loading characteristic.

21. A wheel assembly according to any one of claims 18 to 20, wherein the first loading characteristic and the second loading characteristic replicate a first stiffness and a second stiffness respectively.

22. A drive assembly for a Magnus rotor, the drive assembly comprising: one or more drive wheel mechanisms, the or each drive wheel mechanism comprising a drive wheel positionable to roll against a running surface of a rotor in use and a drive mechanism for supplying torque to drive the drive wheel in rotation and drive the rotor in use in rotation; and one or more idler mechanisms, the or each idler mechanism comprising an idler wheel freely rotatable and positionable, in use, to roll against a running surface of the rotor as the rotor rotates, in: At least one drive wheel includes a first tire having a first tire composition, and at least one idler wheel includes a second tire having a second tire composition different from the first tire composition; and / or At least one drive wheel mechanism further comprises a biasing mechanism configured to bias the corresponding drive wheel towards the running surface in use, the biasing mechanism being configured to increase the degree of bias applied as torque supplied by the drive mechanism increases.

23. The drive assembly of claim 22, wherein the first tire is a pneumatic tire.

24. A drive assembly according to claim 22 or 23, wherein the first tire component is formed from a material that is or includes a rubber material.

25. A drive assembly according to any one of claims 22 to 24, wherein the second tyre is a solid tyre.

26. A drive assembly according to any one of claims 22 to 25, wherein the second tire component is formed of a material that is or includes a polyurethane material and / or a metallic material.

27. The drive assembly of claim 26, wherein the polyurethane material has a Shore hardness of 70A or higher.

28. The drive assembly of claim 26, wherein the Brinell hardness of the metal material is 100 HB or higher.

29. A drive assembly according to any one of claims 22 to 28, further comprising a support structure, wherein the one or more drive wheel mechanisms and the one or more idler wheel mechanisms are mounted on the support structure, wherein at least one biasing mechanism includes a swinging chassis pivotally connecting the corresponding drive wheel to the support structure, and the biasing mechanism is configured to bias the swinging chassis to pivot relative to the support structure so that as the torque supplied by the drive mechanism increases, the drive wheel is increasingly pushed toward the running surface.

30. An offset assembly for a wheel of a Magnus rotor, the offset assembly comprising: a first coupling connectable to a support structure to mount one or more wheels relative to the vessel; a second coupling connectable to a wheel rotatable about a wheel axis whereby, in use, the wheel rolls against a running surface of the rotor as the rotor rotates about the rotor axis; and a biasing member interconnected with the first coupling and the second coupling and configured to, in use, urge the wheel axis toward the running surface with a force related to the displacement, wherein when the wheel axis is in a first displacement region, the biasing member urges the wheel toward the running surface according to a first force characteristic, and when the wheel axis is in a second displacement region, the biasing member urges the wheel toward the running surface according to a second, different force characteristic.

31. A biasing assembly according to claim 30, wherein in use, the first displacement region is closer to the running surface in a neutral position than the second displacement region.

32. The biasing assembly of claim 31, wherein the first force characteristic results in a lower level of bias being applied than the second force characteristic results.

33. A biasing assembly according to any one of claims 30 to 32, wherein the first displacement region transitions to the second displacement region at a predetermined transition point.

34. A biasing assembly according to any one of claims 30 to 33, wherein the biasing assembly comprises a first biasing element defining the first force characteristic and a second biasing element defining the second force characteristic.

35. A biasing assembly according to claim 34, wherein the first biasing element is or comprises a spring, a pneumatic actuator and / or a hydraulic actuator.

36. A biasing assembly according to claim 35, wherein the first biasing element is or comprises a pneumatic actuator or a hydraulic actuator having a pressure accumulator.

37. A biasing assembly according to any one of claims 34 to 36, wherein the second biasing element is or comprises a resilient block, preferably formed of or comprising a resilient material.

38. A biasing assembly according to any one of claims 30 to 37, wherein the second force characteristic is selected to prevent resonant oscillation of the rotor in use over a desired operating speed range.

39. A wheel assembly for a Magnus rotor, the wheel assembly comprising: a support structure, the support structure defining a pitch circle; at least one wheel mounted to the support structure and rotatable about a wheel axis to roll against a running surface of the rotor as the rotor rotates, in use; and 39. At least one offset assembly according to any one of claims 30 to 38, wherein the or each first coupling is connected to the support structure and the or each second coupling is connected to a respective wheel.

40. The wheel assembly of claim 39, wherein: The at least one wheel is a plurality of wheels and the at least one biasing assembly is a corresponding plurality of biasing assemblies; and The second force characteristic of each biasing assembly replicates a stiffness, and the second force characteristic of the plurality of biasing assemblies replicates a stiffness effective for the rotor in use that is greater than an expected moving mass of the rotor multiplied by the square of an expected maximum operating angular velocity of the rotor.

41. A wheel assembly according to claim 40, wherein the effective stiffness of the rotor in use is 1.5 to 10 times the effective moving mass of the rotor multiplied by the square of the maximum operating angular velocity of the rotor, preferably 2 to 5 times the effective moving mass of the rotor multiplied by the square of the maximum operating angular velocity of the rotor.

42. A universal wheel mechanism for a Magnus rotor, the universal wheel mechanism comprising: a wheel rotatable about a wheel axis to roll against a running surface of the rotor in use as the rotor rotates about the rotor axis; A mounting assembly which, in use, rotatably supports the wheel relative to a support structure and includes a gimbal support configured to allow the wheel axis to pivot about a gimbal axis extending substantially perpendicular to the wheel axis, wherein, in use, the wheel axis and the rotor axis extend along a substantially common radial plane and the gimbal support is configured such that the gimbal axis further extends substantially perpendicular to the radial plane.

43. The universal wheel mechanism according to claim 42, wherein: The outer surface of the wheel is substantially cylindrical so that, in use, a contact line or contact area is established between the wheel and the running surface, the length of which is substantially equivalent to the height of the wheel, and the center of which represents the center of force between the wheel and the running surface.

44. The universal wheel mechanism according to claim 43, wherein the height of the wheel is equal to or greater than 50% of the diameter of the wheel.

45. A universal wheel mechanism according to claim 43 or claim 44, wherein the universal axis extends closer to the contact line or the contact area than the wheel axis; preferably, the universal axis extends through the contact line or the contact area; more preferably, the universal axis extends through the force center.

46. ​​The universal wheel mechanism according to claim 45, wherein: The gimbaled support defines a first pivot point and a second pivot point, whereby the gimbaled support provides a gimbaled support force acting along a gimbaled support axis extending through the first pivot point and the second pivot point; and The pivot points are arranged relative to each other such that the gimbal axis coincides with the force centre.

47. A caster mechanism according to claim 45 or claim 46, further comprising a biasing support configured to resist pivoting of the wheel axis about the caster axis.

48. The universal wheel mechanism according to claim 47, wherein the offset support member provides an offset support force acting along the axis of the offset support member, the offset support force offsetting the rotational force acting around the force center of the universal wheel mechanism, the rotational force being generated by the weight of the universal wheel mechanism.

49. A caster mechanism according to any one of claims 42 to 44, wherein the caster axis extends closer to the centre of gravity of the caster mechanism than the curved outer surface of the wheel; preferably substantially passing through the centre of gravity of the caster mechanism.

50. The Magnus rotor of any one of claims 1 to 11, wherein the plurality of wheels define one or more of the following: A wheel assembly according to any one of claims 12 to 21; A drive assembly according to any one of claims 22 to 29; and A wheel assembly according to any one of claims 39 to 41.

51. A Magnus rotor as claimed in any one of claims 1 to 11 or 50, wherein at least one wheel forms part of a universal wheel mechanism as claimed in any one of claims 42 to 49.

52. A Magnus rotor comprising: a rotor rotatable about a rotor axis and having an inner running surface; a support structure configured to rotatably support the rotor; as well as a plurality of wheels, each wheel rotatably mounted to the support structure for rotation about a respective wheel axis extending substantially parallel to the rotor axis and positioned so that the wheel rolls against the inner running surface as the rotor rotates about the support structure, The plurality of wheels define one or more of the following: A wheel assembly according to any one of claims 12 to 21; A drive assembly according to any one of claims 22 to 29; and A wheel assembly according to any one of claims 39 to 41.

53. A Magnus rotor according to claim 52, wherein at least one wheel forms part of a universal wheel mechanism according to any one of claims 42 to 49.

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