A fluid machine, a propulsion system for a marine vessel and a turbine

Abstract

Invention relates to a fluid machine (10), comprising - a circular stator assembly (12) with a winding aggregate (13), - a circular rotor assembly (16) with magnets (17) co-operating with the winding aggregate (13) and blades (18) in force transmission connection with the rotor assembly (16), - the winding aggregate (13) comprise a first circular array of winding units (130.1) and a second circular array of winding units (130.2) in the stator assembly (12) axially spaced from each other, and - the magnets (17) in the rotor assembly (16) comprise a first circular array of magnets (170.1) and a second circular array of magnets (170.2) and the first circular array of magnets (170.1) is arranged on the axial side of the first circular array of winding units (130.1) and the second circular array of magnets (170.2) is arranged on the axial side of the second circular array of winding units (130.2).

Description

A fluid machine, a propulsion system for a marine vessel and a turbineTechnical field

[0001] The present invention relates to a fluid machine according to the preamble of claim 1.

[0002] The present application generally relates to fluid machines, and more particularly to the design and operation of devices that convert fluid energy into mechanical energy or vice versa.Background art

[0003] In many types of electrical machine, electric currents in a stator create a travelling magnetic field that interacts with a set of electric currents, a set of permanent magnets or a set of ferromagnetic features on the moving part of the machine, i.e. a rotor in the case of a rotary machine, or a translator in the case of a linear machine. The usual method of creating the travelling field is to use three component windings housed together in a laminated iron stator through which three alternating currents travel either from a three-phase electrical power supply to three phase electricity consumer. Each component winding has a cyclic distribution of coils and the three component windings are placed with their magnetic axes spaced at intervals of 1 / 3 of a wavelength along the stator. The alternating currents fed to the windings have relative phase differences of 120 degrees. As a result, the combined magnetic flux approximates a sinewave of constant amplitude travelling at a speed equal to one wavelength of the cyclic distribution during one cycle of the alternating current.

[0004] A shaftless fluid machine is an advanced type of fluid handling device that eliminates the traditional central shaft. The fluid machine is provided with a rotor which is supported to stationary and generally circular body at a rim of the rotor. Such a fluid machine can be configured to recovery energy from fluid flowing through the fluid machine as well as to move fluid by rotating the rotor with energy supplied to the fluid machine.

[0005] A rim-driven fluid machine, such as a rim-driven propeller, is a type of propulsion or turbine system where the blades are connected to a ring (or rim) rather than a central hub. The rim houses an electric motor or generator, with the stator fixed to the rim and the rotor connected to the blades. This configuration allows the electric machine to drive the propeller or to be driven by it directly from the outer edge. The benefits of this design include reduced noise, higher efficiency, and the elimination of the central shaft, which improves fluid flow. These systems are commonly used in marine applications, like ship thrusters, where precise, efficient, and low-vibration propulsion is required. Rim-driven propellers, while offering advantages like reduced noise, better flow efficiency, and compact design, also have some common disadvantages. The integration of the motor into the rim makes the design and manufacturing process more complex and expensive compared to traditional propellers. Rim-driven designs may face limitations in the maximum power they can handle, making them less suitable for high-power applications compared to traditional shaft-driven propellers.

[0006] An object of the invention is to provide a fluid machine in which the performance is considerably improved compared to the prior art solutions.Disclosure of the Invention

[0007] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention. Embodiments of the invention are associated with various advantages and / or technical effects.

[0008] A fluid machine according to the invention, comprises- a circular stator assembly having a circular space, the circular stator assembly comprising a winding aggregate,- a circular rotor assembly, the rotor assembly comprising magnets which are configured to the rotor assembly to co-operate with the winding aggregate in the stator assembly, and several blades in force transmission connection with the rotor assembly,- axial and radial bearings configured to support the rotor to the stator assembly, wherein- the winding aggregate comprise a first circular array of winding units and a second circular array of winding units in the stator assembly axially spaced from each other, and- the magnets in the rotor assembly comprise a first circular array of magnets and a second circular array of magnets and the first circular array of magnets is arranged on the axial side of the first circular array of winding units and the second circular array of magnets is arranged on the axial side of the second circular array of winding units.

[0009] The dual circular arrays of winding units and magnets enhance the magnetic interaction within the fluid machine, leading to improved torque generation and more efficient energy conversion.

[0010] In the present invention the fluid machine comprises two axial flux electric motors arranged to substantially same radial position, which considerably decreases overall diameter of the fluid machine.

[0011] The axial spacing between the two circular arrays of winding units allows for a more balanced distribution of magnetic forces, which can reduce vibration and noise during operation, contributing to a longer lifespan of the machine.

[0012] The configuration of the winding aggregates in two separate arrays can facilitate cooling and heat dissipation, as there is more surface area exposed to cooling mechanisms, thus improving the thermal management of the fluid machine.

[0013] The fluid machine provides the advantage of modularity, enabling flexible design configurations and easier maintenance or upgrades.

[0014] According to an aspect of the invention the first circular array of winding units, the second circular array of winding units, the first circular array of magnets and a second circular array of magnets are at a common operational radial distance from a center of rotation of the rotor assembly.

[0015] The equal radial positioning of the arrays makes the design radially slim, potentially reducing space requirement, production costs and facilitating easier assembly and maintenance.

[0016] Positioning the winding units and magnets at substantially the same radial distance, capable of interact with each other, from the center of rotation ensures a uniform magnetic field, which can lead to consistent and stable motor performance.

[0017] The symmetrical arrangement of the magnetic components at equal radial distances minimizes the risk of magnetic flux imbalances, which can enhance the efficiency of the fluid machine.

[0018] According to an aspect of the invention the first circular array of magnets and the second circular array of magnets are arranged axially between the first circular array of winding units and the second circular array of winding units.

[0019] Arranging the magnets axially between the winding units can create a compact and efficient magnetic circuit, which may result in a higher power density and reduced material usage.

[0020] This configuration can provide a direct path for magnetic flux between the arrays of magnets and winding units, potentially increasing the electromagnetic efficiency of the machine.

[0021] The axial arrangement of the first and second circular arrays of magnets between the winding units can optimize the magnetic interaction, potentially increasing the torque and efficiency of the fluid machine.

[0022] This configuration can also contribute to a more balanced distribution of magnetic forces, which can reduce vibration and noise during operation, leading to a smoother and quieter performance.

[0023] According to an aspect of the invention the first circular array of winding units and the second circular array of winding units are arranged axially between the first circular array of magnets and the second circular array of magnets.

[0024] Placing the winding units axially between the magnets can protect the more sensitive winding units from environmental contaminants and physical damage, potentially extending the operational life of the fluid machine.

[0025] This arrangement can allow for a more even distribution of the magnetic field across the winding units, which may result in smoother operation and reduced electromagnetic interference.

[0026] The axial arrangement of the first and second circular arrays of winding units between the corresponding arrays of magnets optimizes the magnetic coupling, thereby enhancing the efficiency of electromagnetic energy conversion.

[0027] This configuration allows for a more compact design, reducing the overall size of the fluid machine and facilitating its integration into various applications with limited space availability.

[0028] The axial alignment of the winding units with the magnets can provide improved thermal management by facilitating uniform heat distribution and dissipation throughout the machine.

[0029] According to an aspect of the invention the fluid machine comprises a body to which the stator assembly is arranged, and the rotor assembly is radially inside the body.

[0030] By having the rotor assembly inside the stator assembly, the fluid machine can be easily adapted for use as a marine propeller.

[0031] The arrangement of the rotor assembly radially inside the body allows for a more compact design, which can reduce the overall size and footprint of the fluid machine, making it suitable for applications where space is limited.

[0032] By having the rotor assembly inside the stator, the design may provide improved protection for the rotor from external environmental factors, potentially increasing the durability and operational lifespan of the machine.

[0033] According to an aspect of the invention the fluid machine comprises a body to which the stator assembly is arranged, and the rotor assembly is radially outside the body.

[0034] By having the rotor assembly inside the stator assembly, the fluid machine can be easily adapted for use as a marine propeller as well as a turbine.

[0035] Positioning the rotor assembly radially outside the body can facilitate easier access for maintenance, inspection, and replacement of the rotor and its components such as blades, thereby reducing downtime and maintenance costs.

[0036] This configuration may allow for a larger rotor diameter compared to an internal rotor design, which can increase the torque output and efficiency of the fluid machine for certain applications.

[0037] According to an aspect of the invention the bearing comprises a self-positioning padded bearing.

[0038] The incorporation of a self-positioning padded bearing allows for self-adjustment to accommodate misalignments, including misalignments in direction of normal to the surface of the bearing, provide elasticity in several degrees of freedom, and reduces stress on the bearing, thereby enhancing the operational lifespan of the fluid machine.

[0039] The self-positioning feature of the padded bearing can absorb and dampen vibrations and misalignment of the rotor, leading to quieter operation and improved performance in environments sensitive to noise and vibration.

[0040] According to an aspect of the invention axial bearings comprise two radially extending bearing surfaces and an array of self-positioning pad bearings, which form together axial thrust bearings, and the arrays of self-positioning padbearings are arranged to substantially same radial distance as the first circular array of winding units, the second circular array of winding units, the first circular array of magnets and a second circular array of magnets.

[0041] This way in the present invention the fluid machine comprises two electric motors and axial bearings arranged to same radial position, which considerably decreases overall diameter, or alternatively radial thickness of the fluid machine.

[0042] According to an aspect of the invention the rotor assembly comprises a center axis of rotation defining axial direction and radial direction, and the axial bearings comprise two radially extending bearing surfaces and an array of selfpositioning pad bearings facing both of the radially extending bearing surfaces, the radial bearings comprise one axially extending circular bearing surface and an array of self-positioning pad bearings facing the axially extending circular bearing surface.

[0043] The inclusion of two radially extending bearing surfaces with an array of self-positioning pad bearings enables the axial bearings to accommodate misalignments and distribute loads evenly, enhancing the stability and reliability of the rotor's operation.

[0044] The design of the radial bearings with one axially extending circular bearing surface and self-positioning pad bearings facing it provides precise control of radial movements and reduces wear, leading to a longer bearing life and improved machine performance.

[0045] According to an aspect of the invention the first circular array of winding units and the second circular array of winding units, the first circular array of magnets and a second circular array of magnets, and the axial bearings are at a same radial distance from a center of rotation the rotor assembly.

[0046] Having the first and second circular arrays of winding units, magnets, and axial bearings at the same radial distance from the center of rotation ensures a balanced distribution of magnetic forces, which can minimize vibrations and noise during operation.

[0047] This symmetrical arrangement of components can also contribute to uniform heat dissipation, reducing the risk of overheating and improving the thermal efficiency of the fluid machine.

[0048] According to an aspect of the invention the first circular array of winding units and the second circular array of winding units are arranged axially between the first circular array of magnets and the second circular array of magnets, and the stator assembly comprises power distributor bars for each electric phase, which power distributor bars are arranged between the first circular array of winding units and the second circular array of winding units.

[0049] In addition to the effect that the axial spacing between the two circular arrays of winding units allows for a more balanced distribution of magnetic forces, which can reduce vibration and noise during operation, contributing to a longer lifespan of the machine, this arrangement provides axially centralized location for the power distributor bars, and it also makes it possible to provide common power distributor bars for the first circular array of winding units and the second circular array of winding units.

[0050] According to an aspect of the invention the winding aggregate in the stator assembly is comprised of multiple winding units, which comprise a core having adjacent core plates and a first core plate end at a first end of the core and a second core plate end at second end of the core, opposite to the first end, and a coil arranged on the core.

[0051] The modular design of the winding aggregate with multiple winding units allows for ease of manufacturing and assembly, as each unit can be produced separately and then assembled into the stator assembly.

[0052] The presence of a core with adjacent core plates and core plate ends at both ends of the core provides structural integrity and stability to the winding aggregate, enhancing the durability and lifespan of the fluid machine.

[0053] The arrangement of a coil on the core optimizes the electromagnetic interaction within the stator assembly, improving the efficiency and performance of the fluid machine.

[0054] According to an aspect of the invention the first core plate end is provided with dovetail groove parallel to core plates on its back face.

[0055] The dovetail groove on the back face of the first core plate end facilitates a secure and precise connection with complementary components, reducing the likelihood of misalignment and improving the overall robustness of the assembly.

[0056] The parallel alignment of the dovetail groove with the core plates ensures that the forces exerted during operation are evenly distributed, minimizing stress concentrations and potential damage to the stator assembly.

[0057] According to an aspect of the invention a dovetail key, which is provided with attachment means, such as at least two threaded bolts and at least one position pin on its back side, is positioned to the dovetail groove of first core plate end.

[0058] The use of a dovetail key with attachment means, such as threaded bolts and position pins, provides a reliable and easily adjustable method for securing the key bar to the first core plate end, enhancing the maintainability of the fluid machine.

[0059] The attachment means on the back side of the dovetail key allow for a strong mechanical connection that can withstand the operational stresses and vibrations encountered in the fluid machine, contributing to a stable and consistent performance.

[0060] According to an aspect of the invention the first core plate ends are arranged side by side against each other when assembled, forming a back iron so as to close magnetic flux and provide a path for the magnetic flux generated by the coils.

[0061] The side-by-side arrangement of the first core plate ends when assembled into a back iron effectively closes the magnetic flux, which maximizes the magnetic efficiency of magnetic circuit in the stator assembly and reduces energy losses.

[0062] The contiguous formation of the back iron by the first core plate ends provides a uniform magnetic path, which can lead to improved electromagnetic characteristics and a more compact design of the fluid machine.

[0063] According to an aspect of the invention the winding aggregate of the stator assembly comprises a pair or circular stator frames, each of which includes a radially extending flat portion, wherein the winding units are attached on a first side of the flat portion, and that the stator assembly comprises power distributor bars for each electric phase, each of which power distributor bars is attached on a second side of the flat portion.

[0064] The configuration of the stator assembly with circular stator frames and radially extending flat portions provides a robust structure that can effectively support the winding units, enhancing the mechanical stability of the machine.

[0065] The attachment of power distributor bars on the opposite side of the flat portion from the winding units allows for a compact design, reducing the overall size of the stator assembly and potentially minimizing the footprint of the fluid machine.

[0066] According to an aspect of the invention the power distributor bars are of different diameters and the winding wires of winding units are guided axially through the flat portion of the stator frame radially between the power distributor bar having the greatest diameter of the distributor bars and the power distributor bar having the smallest diameter of the distributor bars.

[0067] Utilizing power distributor bars of different diameters facilitates the organization of winding wires, which can improve the electrical efficiency by reducing the resistance and inductance variations across the phases.

[0068] The axial guidance of winding wires through the flat portion of the stator frame between the power distributor bars of varying diameters can enhance the cooling of the wires, as it allows for better airflow and heat dissipation.

[0069] According to an aspect of the invention the circular stator frame comprises an axially extending portion at radially outer edge and radially inner edge of the radially extending flat portion, which axially extending portions extends axially to both directions from the radially extending flat portion, forming a first axially opening groove in the stator frame and a second axially opening groove in the stator frame, wherein the winding units are arranged in the first axially opening groove and the distributor bars are arranged in the second axially opening groove.

[0070] The inclusion of axially extending portions at the edges of the radially extending flat portion, forming grooves, provides dedicated spaces for the winding units and distributor bars, which can simplify assembly and maintenance procedures.

[0071] The design of the first and second axially opening grooves in the stator frame ensures that the winding units and distributor bars are securely housed, protecting them from external environmental factors and reducing the risk of damage during operation.

[0072] According to an aspect of the invention the first axially opening groove is provided with a barrier covering the groove.

[0073] The presence of a barrier on the first axially opening groove can prevent debris or foreign objects from entering the groove, thereby protecting the winding units from potential contamination and damage.

[0074] The barrier can also serve to contain the winding units within the groove, reducing the likelihood of displacement or vibration-induced wear, which contributes to the reliability and longevity of the fluid machine.

[0075] According to an aspect of the invention the second axially opening groove is filled with insulation material, which provides insulation against water ingress, electric insulation and assist heat dissipation.

[0076] The inclusion of insulation material in the second axially opening groove enhances the thermal management of the fluid machine, potentially increasing its efficiency and longevity by reducing the risk of overheating.

[0077] The insulation material can also provide electrical insulation, which can prevent short circuits and improve the overall safety and reliability of the fluid machine.

[0078] According to an aspect of the invention the first circular array of winding units is attached to a first circular stator frame and a second circular array of winding units is attached to a second circular stator frame in the pair of the circular stator frames, wherein the stator frames are arranged their winding units facing each other.

[0079] Attaching the first and second circular arrays of winding units to separate stator frames allows for modular construction, which can simplify manufacturing and maintenance processes.

[0080] The arrangement of the winding units facing each other on the stator frames can create a more uniform magnetic field, which can improve the operational efficiency and performance of the fluid machine.

[0081] According to an aspect of the invention the pair of the circular stator frames and the winding units attached to the frames are assembled inside a body of the fluid machine.

[0082] Assembling the pair of circular stator frames and the winding units inside the body of the fluid machine can protect these components from external environmental factors, such as dust and moisture, thereby enhancing durability.

[0083] The internal assembly can also lead to a more compact design, reducing the overall size of the fluid machine and making it more suitable for applications where space is at a premium.

[0084] According to an aspect of the invention the magnets in the rotor assembly are permanent magnets.

[0085] Utilizing permanent magnets in the rotor reduces the need for external power to maintain magnetic fields, leading to lower operational costs and higher reliability due to fewer components susceptible to wear and failure.

[0086] Permanent magnets can produce stronger magnetic fields than electromagnets of comparable size, potentially increasing the torque and overall performance of the fluid machine. This way the fluid machine comprises preferably two axial flux permanent magnet motors at same radial distance from center axis.

[0087] According to an aspect of the invention the rotor assembly comprises a circular main rotor ring arranged into the circular space of the stator assembly, and the first circular array of magnets and the second circular array of magnets are arranged radially outside the main rotor ring, both at the same radial distance, such that magnetic flux is substantially axial.

[0088] The radial arrangement of the magnets around the main rotor ring at the same radial distance ensures a uniform magnetic field across the rotor assembly, which can lead to smoother operation and reduced vibration.

[0089] Positioning the magnets such that the magnetic flux is substantially axial, aligns the natural flow of magnetic with the lines of force, improving the magnetic efficiency and potentially reducing energy losses.

[0090] The circular main rotor ring provides structural integrity to the rotor assembly, ensuring that the magnets are securely held in place during operation, which can extend the lifespan of the machine.

[0091] According to an aspect of the invention the main rotor ring comprises a first radially and outwardly extending rotor ring and a second radially andoutwardly extending rotor ring, axially at a distance from each other, wherein the first circular array of magnets is attached to the first radially and outwardly extending rotor ring, and the second circular array of magnets is attached to the second radially and outwardly extending rotor ring.

[0092] The use of radially and outwardly extending rotor rings for attaching the magnets allows for a robust and stable construction, which can withstand the mechanical stresses encountered during high-speed rotation.

[0093] Having the magnets attached to separate rotor rings axially distanced from each other can facilitate assembly and maintenance, as each array of magnets can be accessed and serviced independently.

[0094] This design enables precise positioning of the magnets, which is critical for maintaining the balance of the rotor and ensuring optimal magnetic interaction with the stator, leading to improved operational efficiency.

[0095] According to an aspect of the invention the rotor rings are axially spaced from each other leaving a space between the rotor rings, wherein the first circular array of magnets is arranged to an axial outer face of the first rotor ring, opposite to the space, and the second circular array of magnets is arranged to an axial outer face of the second rotor ring, opposite to the space.

[0096] The axial spacing between the rotor rings with the magnets arranged on their outer faces opposite the space allows for a compact and efficient magnetic field interaction, which can lead to improved electromagnetic efficiency and reduced energy losses within the fluid machine.

[0097] The configuration of the magnets on the axial outer faces of the rotor rings facilitates easier assembly and maintenance of the fluid machine, as the magnets are readily accessible and can be replaced or serviced without disassembling the entire machine.

[0098] According to an aspect of the invention the rotor assembly comprises circular main rotor ring arranged into the circular space of the stator assembly,wherein the axial and radial bearings are arranged between the main rotor ring and the stator assembly.

[0099] The arrangement of axial and radial bearings between the circular main rotor ring of the rotor assembly and the stator assembly ensures stable and precise rotation of the rotor, which can result in reduced vibration and noise during operation, enhancing the machine's overall performance and longevity.

[0100] The presence of bearings on both axial and radial planes provides robust support for the rotor, allowing the fluid machine to handle higher loads and operate effectively under varying operational conditions, including changes in fluid pressure and flow rates.

[0101] According to an aspect of the invention the main rotor ring of the rotor comprises a first radially and outwardly extending rotor ring extending around the main rotor ring, and a second radially and outwardly extending rotor ring extending around the main rotor ring, axially spaced from each other leaving a space between the rotor rings, and the stator assembly comprises a bearing support attached to a body of the fluid machine, which bearing support extends radially inwards into the space between the first and the second rotor ring, and that axial thrust bearing is arranged between the bearing support and the first and the second rotor ring.

[0102] The bearing support extending radially inwards into the space between the rotor rings and the inclusion of an axial thrust bearing between the bearing support and the rotor rings contribute to the effective absorption of axial loads, which can improve the operational stability and reduce wear on the rotor assembly.

[0103] The strategic placement of the bearing support within the space between the rotor rings allows for a more compact design of the fluid machine, potentially reducing the overall size and material usage without compromising the structural integrity or performance capabilities of the machine.

[0104] According to an aspect of the invention the main rotor ring of the rotor comprises a axially extending radial bearing surface between the first radially and outwardly extending rotor ring and the second radially and outwardly extending rotor ring, and that radial bearing is arranged between the axially extending radial bearing surface of the main rotor ring and radially inner surface of the bearing support.

[0105] The axially extending radial bearing surface between the rotor rings and the corresponding radial bearing arranged between this surface and the radially inner surface of the bearing support provides a dedicated load-bearing interface, which can minimize friction and wear, leading to a longer service life of the bearing components.

[0106] The specific arrangement of the radial bearing in relation to the main rotor ring of the rotor ensures that radial loads are evenly distributed, which can enhance the dynamic balance of the rotor and improve the fluid machine's efficiency by maintaining a consistent gap between rotating and stationary parts.

[0107] According to an aspect of the invention the bearing support is generally of T-shaped cross section, having a flange part attached to the body of the fluid machine, wherein axial bearings are arranged to both sides of the web part.

[0108] The T-shaped cross-section of the bearing support provides a robust and stable platform for the bearings, ensuring reliable operation under varying loads and reducing the likelihood of mechanical failure.

[0109] The arrangement of axial bearings to both sides of the web part allows for the even distribution of axial forces, which can improve the balance of the fluid machine and result in smoother operation.

[0110] According to an aspect of the invention a self-positioning padded bearing comprise a resilient attachment means.

[0111] The resilient attachment means for the self-positioning padded bearing enables it to adapt to thermal expansion and contraction, maintaining optimal contact and reducing wear over time.

[0112] The flexibility provided by the resilient attachment means allows for better shock absorption or forces, protecting the fluid machine from potential damage due to sudden impacts or overloads.

[0113] According to an aspect of the invention the magnets comprise a first circular array of magnets and a second array of magnets, wherein the first circular array of magnets is arranged to face the first circular array of winding units and the second circular array of magnets is arranged to face the second circular array of winding unit, forming two electromechanical machine assemblies assembled axially spaced from each other.

[0114] The dual circular arrays of magnets facing corresponding winding units create two electromechanical assemblies that can operate independently or in tandem, offering redundancy and the potential for higher power output.

[0115] The axial spacing between the two electromechanical machine assemblies allows for improved heat dissipation, which can enhance the efficiency and reliability of the fluid machine by preventing overheating.

[0116] According to an aspect of the invention the fluid machine is a shaftless propulsor, preferably a thruster for a marine vessel, wherein the blades are directly connected to the main rotor ring.

[0117] The direct connection of the blades to the main rotor ring in the shaftless propulsor design simplifies the overall structure, reducing space requirement, potential points of failure and maintenance requirements.

[0118] Elimination of the shaft in the thruster allows for a more compact design, potentially reducing the drag and improving the hydrodynamic efficiency of the marine vessel.

[0119] The shaftless configuration can lead to a reduction in the weight of the thruster system, contributing to improved fuel efficiency and performance of the marine vessel.

[0120] According to an aspect of the invention the fluid machine is a shaftless tunnel thruster and the body of the fluid machine is a frame tube.

[0121] Utilizing a frame tube as the body of the fluid machine provides a robust and rigid structure that can withstand the stresses and strains encountered during operation.

[0122] The frame tube design allows for ease of assembly and disassembly, facilitating maintenance and repair operations.

[0123] The inherent simplicity of a frame tube body can lead to cost savings in manufacturing due to the reduction in complex components and assembly processes.

[0124] According to an aspect of the invention the frame tube is a sleevelike body frame which has a cylindrical outer surface, and which has axial length which is 5 - 15 times of radial thickness of the body frame.

[0125] The sleeve-like body frame with a cylindrical outer surface provides a streamlined profile that can minimize turbulence and flow separation, leading to improved fluid dynamic performance.

[0126] A body frame with an axial length that is significantly greater than its radial thickness ensures a high degree of structural integrity, enabling the fluid machine to operate reliably under high-pressure conditions.

[0127] According to an aspect of the invention the fluid machine is a shaftless propulsor for a marine vessel, wherein the blades are connected to the main rotor ring by an axial extension, such as a shaft, which is coupled to the main rotor ring.

[0128] The connection of the blades to the main rotor ring via an axial extension, such as a shaft, allows various practical applications replacing conventional shaft power trains.

[0129] The use of a shaft to connect the blades to the main rotor ring can provide a means for adjusting the blade pitch, offering the ability to optimize propulsion under varying load conditions.

[0130] The shafted design may facilitate the transmission of torque from the main rotor ring to the blades more effectively, potentially increasing the thrust generated by the propulsor.

[0131] According to an aspect of the invention a water feeding system is provided, which is configured to feed filtered water for the bearing pads. This way the bearing pads are maintained at clean environment since substantially no debris can enter inside the bearing and / or motor area of the propulsor from outside water.

[0132] According to an aspect of the invention a body of the propulsor has a cylindrical form having a first diameter, and the main rotor ring has a second diameter, wherein ratio of the first diameter to difference between the first and the second diameter is 8 - 12.

[0133] This provides very slim structure which thereby improves hydrodynamical behaviour of the fluid machine.

[0134] According to an aspect of the invention the blades of the thruster are connected to the main rotor ring and to a propeller hub arranged to the center axis A of the thruster, wherein the hub is supported only to the blades.

[0135] A hub in the middle increase strength of the blades.

[0136] According to an aspect of the invention the hub has diameter which is 10-20% of outer diameter of the thruster. This has been found beneficial for supporting the blades while still providing proper hydrodynamical performance.

[0137] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.Brief Description of Drawings

[0138] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in whichFigures 1 to 4 disclose alternative aspects of the invention,Figure 5 illustrates a fluid machine according to an embodiment of the invention, Figure 6 illustrates cross-sectional view of stator assembly and rotor assembly of the fluid machine shown in the figure 5,Figure 7 illustrates a fluid machine according to another embodiment of the invention,Figure 8 shows a cross-sectional view of stator frame and rotor of the fluid machine shown in the figure 7,Figure 9 illustrates a winding unit according to an embodiment of the invention, Figure 10 illustrates a core for a winding unit according to an embodiment of the invention,Figure 11 illustrates a dovetail key of attaching a winding unit according to an embodiment of the invention,Figure 12 illustrates a stator frame according to an embodiment of the invention, Figure 13 illustrates a constructional part of the rotor assembly according to an embodiment of the invention,Figure 14 illustrates principal of interaction between the winding units in the stator assembly according to an embodiment of the invention,Figure 15 illustrates a detail of the rotor assembly according to an embodiment of the invention,Figure 16 illustrates a detail of the rotor assembly according to an embodiment of the invention,Figure 17 illustrates details of bearings of the fluid machine according to an embodiment of the invention,Figure 18 illustrates details of a bearing pad according to an embodiment of the invention,Figure 19 illustrates further details of a bearing pad according to an embodiment of the invention,Figure 20 illustrates a tunnel thruster for a marine vessel according to an embodiment of the invention, andFigure 21 illustrates detail of a tunnel thruster according to an embodiment of the invention.Detailed Description of Drawings

[0139] In the following the figures 1 to 4 disclose some alternative aspects of the invention where shaftless fluid machine is utilized. Figure 1 discloses a cross section of a fluid machine 10 according to an embodiment of the invention, which comprises a circular stator assembly 12 and a circular rotor assembly 16. The stator assembly comprises a winding aggregate 13, which goes round the stator assembly. The rotor assembly comprises magnets 17, which are configured to the rotor assembly to co-operate with the winding aggregate 13 in the stator assembly 12 forming an electric machine, a motor or a generator, depending on the practical application. In this embodiment the stator assembly 12 and the rotor assembly 16 are arranged inside a body 22 of the fluid machine 10. The fluid machine 10 comprises several blades 18 in force transmission connection with the rotor assembly 16, in the figure the blades are directly attached to the rotor assembly. The rotor assembly 16 is supported on the stator assembly by axial and radial bearings 20.

[0140] The winding aggregate 13 in the stator assembly comprises a first circular array of winding units 130.1 and a second circular array of winding units 130.2, such that they are axially spaced from each other. On the other hand, the magnets 17 in the rotor assembly comprise a first circular array of magnets 170.1 and a second circular array of magnets 170.2. The rotor assembly 16 comprisesa center axis A of rotation which defines axial direction and radial direction in the fluid machine. The rotor assembly is arranged to rotate about the center axis. The first circular array of magnets 170.1 are arranged on axially on side of the first circular array of winding units 130.1 and the second circular array of magnets 170.2 are arranged on the axially on side of the second circular array of winding units 130.2 such there are two axially spaced individual electric machines, which can function as a motor or generator, arranged in the fluid machine and additionally in both of the electric machines the created magnetic flux is substantially axial.

[0141] In the embodiment of the figure 1 the first circular array of winding units 130.1 , the second circular array of winding units 130.2, the first circular array of magnets 170.1 and a second circular array of magnets 170.2 are substantially at a same radial distance from a center axis A. More precisely the first circular array of magnets 170.1 and the second circular array of magnets 170.2 are arranged axially between the first circular array of winding units 130.1 and the second circular array of winding units 130.2. In the embodiment of the figure 1 the fluid machine 10 comprises an opening inside, and axially through the fluid machine, and blades 18 are arranged in the opening, supported to the rotor assembly 16.

[0142] Figure 2 discloses cross section of a fluid machine 10 according to another embodiment of the invention, which is a shaftless fluid machine. The fluid machine 10 according to the invention comprises a circular stator assembly 12, the stator assembly comprising a winding aggregate 13, which will be explained later in more detailed manner. A fluid machine 10 according to the invention further comprises a circular rotor assembly 16. The rotor assembly comprises magnets 17, which are configured to the rotor assembly to co-operate with the winding aggregate 13 in the stator assembly 12. In this embodiment the stator assembly 12 and the rotor assembly 16 are arranged outside a body 22 of the fluid machine 10. The rotor assembly 16 is supported on the stator assembly by axial and radial bearings 20.

[0143] The winding aggregates 13 and the magnets 17 are similar to that shown in the figure 1. Also, in the figure 2 there are two individual electricmachines arranged in the fluid machine and additionally in both of the electric machines the created magnetic flux is substantially axial.

[0144] In the embodiment of the figure 2 the first circular array of winding units 130.1 , the second circular array of winding units 130.2, the first circular array of magnets 170.1 and a second circular array of magnets 170.2 are substantially at a same radial distance from a center axis A. More precisely the first circular array of magnets 170.1 and the second circular array of magnets 170.2 are arranged axially between the first circular array of winding units 130.1 and the second circular array of winding units 130.2. In the embodiment of the figure 2 the fluid machine 10 may comprise an opening inside the body 22 or the body may occupy totally or partly the space inside the stator assembly. The fluid machine 10 comprises several blades 18 in force transmission connection with the rotor assembly 16, and in the embodiment of figure 2 the blades 18 are arranged radially outside the rotor assembly 16.Figure 3 discloses a fluid machine otherwise similar to that shown in the figure 1 but in this embodiment the first circular array of winding units130.1 and the second circular array of winding units 130.2 are arranged axially between the first circular array of magnets 170.1 and the second circular array of magnets 170.2. Also, in the figure 3 there are two individual electric machines arranged in the fluid machine and additionally in both of the electric machines the created magnetic flux is substantially axial. The first circular array of winding units130.1 and the second circular array of winding units 130.2 are arranged axially at a distance from each other such that there is a space for electric distributor bars 158 for each electric phase 158.1 , 158.2, 158.3. The distributor bars 158 all against inner wall of the 22 body of the fluid machine arranged one after the other in axial direction. Electric connection 310 to the electric motor is provided axially through the body of the fluid machine. In this case the first circular array of winding units130.1 and the second circular array of winding units 130.2 share common distributor bars 158, which makes the fluid machine more compact. There is an array of self-positioning axial pad bearings 208.1 208.2 and an array of self-positioning radial pad bearings 208 arranged at both axial ends.

[0145] The stator assembly 12 comprises end flanges 186 attached to the body 22 behind of which the pad bearings 208,208.120.2 are located and therefore the pad bearings are readily accessible simply by removing the end flanges 186.

[0146] The figures 1 to 4 the bearings 20 include axial bearings which comprise two radially extending bearing surfaces and an array of self-positioning pad bearings facing both of the radially extending bearing surfaces, and the radial bearings comprise one axially extending circular bearing surface and an array of self-positioning pad bearings facing towards the axially extending circular bearing surface.

[0147] In the embodiment shown in the figure 4 the bearings 20 are separate to the electric machine i.e. the winding aggregate 13 and the magnets 17. The embodiment in the figure 4 the stator assembly 12 and the rotor assembly 16 are arranged radially inside a body 22 of the fluid machine 10. However, in the figure 4 the rotor assembly 16 comprises an axial extension which extends axially out from the body 22, blades 18 are arranged to outer side of the extension. The first circular array of winding units130.1 and the second circular array of winding units 130.2 are arranged axially at a distance from each other such that there is a space for electric distributor bars 158 for each electric phase 158.1 , 158.2, 158.3. The distributor bars 158 of different diameter arranged at the same axial position. In this case the first circular array of winding units130.1 and the second circular array of winding units 130.2 share common distributor bars 158, which makes the fluid machine more compact. Wires 132 connects the distributor bars 158 with the winding aggregates 13 However, it is possible to provide each circular array with a dedicated distributor bars. There is an array of self-positioning axial pad bearings 208.1 208.2 and an array of self-positioning radial pad bearings 208 arranged at both axial ends. It is to be noted that actual setup of the distributor bars may vary.

[0148] In all of the figures above describing different aspects of the invention the first circular array of winding units 130.1 and the second circular array of winding units 130.2, the first circular array of magnets 170.1 and a secondcircular array of magnets 170.2, and the axial bearings 20 are at substantially a same radial distance from a center of rotation A of the rotor assembly.

[0149] The rotor assembly interacts with fluid, such as water or the air, and the fluid machine may be configured to convert rotational energy into fluid movement as impellers and propellers, or to convert fluid energy into mechanical energy as turbine blades.

[0150] In the following the figures 5 to 8 disclose further alternative aspects of the invention where shaftless fluid machine is utilized. Figure 5 depicts schematically a fluid machine 10 according to an embodiment of the invention, which is a shaftless propulsor for a marine vessel. In a propulsor its body 22 is preferably a frame tube, which is a sleeve-like body frame. The frame tube has a center axis A, which is also an axis of rotation of the machine. The body has a cylindrical outer surface, and which has axial length which preferably is 5 - 15 times of radial thickness of the body.

[0151] Figure 6 shows a cross-sectional view of stator assembly 12 and rotor assembly 16 of the fluid machine 10 shown in the figure 5. Such a propulsor can be applied to various practical marine applications, such as a tunnel thruster, a nozzle propeller and to waterjet propulsors, just to mention a few. Also, when applying an axial extension in its rotor, the propeller can be positioned axially at a distance from the electric aggregate, in corresponding manner as is disclosed in the figure 4.

[0152] With a reference to figures 5 and 6 the propulsor 10 according to the invention comprises a stator assembly 12 having a circular opening or a space 14 radially inside the stator assembly and the rotor assembly. The stator assembly comprises a winding aggregate 13. The stator assembly 12 is arranged radially inside a body 22 of the fluid machine 10.

[0153] A fluid machine 10 according to the embodiment of the invention further comprises a rotor assembly 16, the rotor assembly comprising magnets 17, which are configured to the rotor assembly to co-operate with the winding aggregate 13 in the stator assembly 12. The magnets in the rotor assembly arepreferably permanent magnets, but they can be also electrically excited magnets in some practical applications. The fluid machine 10 comprises several blades 18 in force transmission connection with the rotor assembly 16. The rotor assembly is supported on the stator assembly by axial and radial bearings, which are not visible in the figure 5.

[0154] The there is a winding aggregate 13 in the stator which comprise a first circular array of winding units 130.1 and a second circular array of winding units 130.2 in the stator assembly 12, such that they are axially spaced from each other. On the other hand, the magnets 17 in the rotor assembly comprise a first circular array of magnets 170.1 and a second circular array of magnets 170.2. The first circular array of magnets 170.1 are arranged axially on a side of the first circular array of winding units 130.1 and the second circular array of magnets 170.2 are arranged axially on the side of the second circular array of winding units 130.2 such that created magnetic flux is substantially axial.

[0155] The first circular array of magnets 170.1 is arranged to face the first circular array of winding units 130.1 and the second circular array of magnets 170.2 is arranged to face the second circular array of winding unit 130.2, forming two axial flux electromechanical machine assemblies, such as electric motors or generators in the stator body assembled axially spaced from each other.

[0156] Figure 7 depicts schematically a fluid machine 10 according to another embodiment of the invention, which is a turbine aggregate in a windmill. Thus, the invention relates also to a turbine for converting fluid energy into electricity, comprising a fluid machine according to the invention. In addition of being a wind turbine such a turbine aggregate is applicable to various other practical applications, such as water turbines. Figure 8 shows a cross-sectional view of stator frame and rotor of the fluid machine 10 shown in the figure 7. With a reference to figure 8 such a turbine aggregate 10 according to the invention comprises a stator assembly 12 having a circular opening or a space 14, the stator assembly comprising winding aggregate13, which will be explained later. The stator assembly 12 is arranged integrated to a body 22 of the fluid machine 10. A turbine aggregate 10 according to the embodiment of the invention in the figures 7 and 8 comprises a rotor assembly 16, the rotor assembly comprising magnets, 17 which are configured to the rotor assembly to co-operate with the windingaggregate in the stator assembly 12. The magnets in the rotor assembly are preferably permanent magnets, but they can be also electrically excited magnets in some practical applications. The fluid machine 10 comprises several blades 18 in force transmission connection with the rotor assembly 16. The rotor assembly is supported on the stator assembly by axial and radial bearings 20.

[0157] There is a winding aggregate 13 in the stator which comprise a first circular array of winding units 130.1 and a second circular array of winding units 130.2 in the stator assembly 12, such that they are axially spaced from each other. On the other hand, the magnets 17 in the rotor assembly comprise a first circular array of magnets 170.1 and a second circular array of magnets 170.2. The first circular array of magnets 170.1 are arranged axially on a side of the first circular array of winding units 130.1 and the second circular array of magnets 170.2 are arranged axially on the side of the second circular array of winding units 130.2 such that created magnetic flux is substantially axial.

[0158] The bearings are preferably of self-positioning pad type. In the figure 8 there is shown a cross section of the bearing, where the axial bearings comprise two radially extending bearing surfaces 202.1 , 202.2 and an array of self-positioning pad bearings 204.1 , 204.2 facing both of the radially extending bearing surfaces. The radial bearings comprise one axially extending circular bearing surface 206 and an array of self-positioning pad bearings 208 facing the axially extending circular bearing surface. The fluid machine according to embodiment shown in the figure 5 has a corresponding bearing structure.

[0159] In the following the structure of winding aggregate 13 is explained in more detailed with reference to figures 9 to 12.

[0160] Figure 9 discloses a winding unit 130, a number of which are installed as the winding aggregate 13 in the stator assembly. The winding aggregate 13 is comprised of multiple winding units 130 going round the stator assembly. The winding unit 130 is built on a core 134, which is shown in more detail in the figure 10. The core 134 comprises several adjacent core plates 136 of soft magnetic material stacked one above the other. The core 134 is preferably made up of thin steel plates, which can also be called laminations, which are stacked together and attached suitably with each other. Each plate is electrically insulatedfrom the next by a thin layer of insulation material, such as a varnish or oxide coating. The lamination plates being thin, planar plates reduce eddy current losses. The core plates can be characterized to be substantially of a shape of an elongated H-letter. Thus, the lamination plates are shaped such that a first core plate end 138 is formed at a first end of the core and a second core plate end 140 at second end of the core, opposite to the first end. Thus, the first core plate end 138 and the second core plate end 140 are extensions of laminating plates outside the area of the coil 152 (see figure 9) and they are at opposite ends of the core 134. The lamination plates in the coiled area may have different widths, that is a dimension between edges which extend from the first core plate end 138 to the second core plate end 140 (width in the position shown in the figure 10) so as to make the upper and lower sides (in the position shown in the figure 10) of the core 134 substantially rounded. The core stack comprises plates of at least 4 different widths, preferably 10 widths and most preferably there are plates of 20 different widths which provides very smoothly rounded sides of the core. Ideally within the coiled area all plates could be of different width but often that is not the most practical solution. The winding unit comprises a wire coil 152 arranged around the core 134 between the first and the second core plate ends. Actual structure, such as number of coil turns and direction of wounding, may differ in practical solutions. Direction of wounding of coiling refers to the way the electrical conductors (wires) are wound around the stator core to form the motor's coils.

[0161] The first core plate end 138 is provided with a dovetail groove 142 parallel to core plates on its back face for attaching the winding unit 130 to the stator assembly 12. Respectively a dovetail key 144, shown in the figure 11 , is provided, which is then attached to the first core plate end 140 by means of the dovetail groove 142 therein. The dovetail key 144 is a flat part which has its narrower back face 146 provided with attachment means, such as at least two threaded bolts 148 and at least one positioning pin 150. The positioning pin is preferably arranged to a middle of the back face and the threaded bolts 148 are symmetrically in respect to the pin 150 at the ends of the back face 146. Winding units are substantially rectangular, or cuboid block arranged to form of circular array about the center.

[0162] The winding aggregate 13 of the stator assembly comprises a pair or circular stator frames 154, as is shown in the figure 6, one of such frames 154 is shown in the figure 12. The stator frame is preferably made of aluminium which has 5 -15 times better thermal conductivity than steel, depending on the specific alloy, the type of steel (e.g., carbon steel, stainless steel) and temperature. Aluminium is preferred particularly in situations where rapid heat transfer is required, whereas steel can be chosen where strength and lower thermal conductivity are beneficial. The stator frame 154 is a ring frame, which includes a radially extending flat portion 156. The flat portion has axial side walls which are planar, radially directed and parallel with each other. The winding units 130 are attached on a first side of the flat portion 156 of the stator frame 154. There are holes provided for the threaded bolts 148 as well as for the positioning pin 150 in the flat portion, and the bolts are tightened to the frame by respective nuts (not shown here). Position pin is used for positioning the winding unit in correct place and its clearance is smaller than clearance of the bolts.

[0163] Each winding unit 130 is placed in the stator frame 154 making use of holes for the winding unit: one hole for the positioning pin, 2 for threaded bolts and optionally 2 holes for wires of the coil of the winding unit 130. The holes for one winding unit are arranged radially spaced such that the winding unit is arranged its laminations being radially directed. It is preferred embodiment of the invention to lead the wires directly through the radially extending flat portion, but still other routes are technically possible. Preferably the pin hole is not a through- hole. The core plate ends are formed such that they have planar ends and sides. The winding units are arranged such that the first core plate ends 138 (see figure 10) are arranged side by side, one against the other to form electric continuity, this way forming a back iron so as to close magnetic flux created when in use. As it can be seen in the figure 12 the winding aggregate 13 in the stator assembly 12 comprises circular power distributor bars 158 for each electric phase 158.1 , 158.2, 158.3. Each of the power distributor bars is attached on the second side of the radially extending flat portion 156, axially opposite to the winding units 130. This way the winding aggregate 13, what comes to the winding units 130 and the power distribution bars 158 is axially substantially short.

[0164] The circular power distributor bars 158 are of ring shape. One bar may extend over the whole circle, but the bar for one phase may be made of several angular sections which are connected to power supply by dedicated cables. Also, in case the distributor bar is a full ring, it may be provided with several power supplies connected to locations being distributed substantially evenly over the bar. Preferably there are at least two cables per phase provided in the motor. This reduces diameter of a single cable and makes installation easier. Sufficient insulation is placed behind the stator frame 154 and around the wires to meet earth insulation requirements (not shown). The power distributor bars 158.1 , 158.2, 158.3, are of different diameters and the winding wires of winding units 130 are guided preferably axially through the flat portion 156 of the stator frame 154 radially between the power distributor bar 158.1 having the greatest diameter and the power distributor bar 158.3 having the smallest diameter. This way all wiring is radially located between the power distributor bars.

[0165] The circular stator frame 154 comprises an axially extending portion 160, 162 both at radially outer edge and radially inner edge of the radially extending flat portion 156. The axially extending portion is a rim-like element arranged perpendicularly to the radially extending flat portion 156. The axially extending portion 160, 162 extends axially to both directions from the radially extending flat portion 156 forming a first axially opening groove 164 in the stator frame and a second axially opening groove 166 in the stator frame, wherein the winding units 130 are arranged in the first axially opening groove 164 and the distributor bars 158 are arranged in the second axially opening groove 166. The first axially opening groove 164 is provided with a barrier 168 on the groove which covers and protects the winding units 130 by sealing the first axially opening groove 164 and by using a fill material such as epoxy, which is preferably filled with thermally conducting fill material. The barrier 168 has outer surface which is flat and parallel to the radially extending flat portion 156 of the stator frame 154. The second axially opening groove 166, where the distributor bars are installed is filled with an electric insulation material.

[0166] With reference to the figure 6, the winding aggerate 13 includes a pair of the circular stator frames 154, provided with the winding units 130 and the power distribution bars as shown in the figure 12. In the pair of the circular statorframes, the stator frames 154 are arranged with their winding units 130 facing each other.

[0167] As it is disclosed in the figures 4 and 8 according to an aspect of the invention the stator assembly comprise a pair of circular stator frames 154 assembled such that the winding units 130 are opposite sides of the pair, and the power distributor bars (even if not shown in the figures) are between the winding units 130. In such embodiment the power distributor bars may serve both of the winding units.

[0168] In the figure 13 there is shown a basic constructional part of the rotor assembly 16 which is shown in the figure 6. Assembly of magnets 17 is shown in the figure 13 in more detailed manner, which results in a circular array of magnets 170. The rotor assembly comprises a circular rotor ring 172. The rotor ring 172 comprises a radially extending portion to which plurality of magnets 17 are attached such that they from the circular array of magnets 170. The magnets 17 are substantially perpendicular to the center axis A of the rotor assembly. There is a back iron 174 arranged between the magnets and the rotor ring to close the magnetic flux. The back iron can be formed of multiple adjacent plates of soft magnetic material such that there is one plate where one magnet is attached. As is shown in the figure the plate, to which the magnet is attached e.g. by gluing, may be attached to the rotor ring 172 by a dovetail joint using a corresponding dovetail key as disclosed in the figure 11 .

[0169] Figure 14 discloses principal of interaction between the winding units 130 in the stator assembly 12 and the magnets 17 in the rotor assembly 16 of one half of the rotor and stator assemblies. There are two permanent magnets 17 arranged for each three winding units 130. The permanent magnet poles are arranged alternately with N pole and S pole and mounted on the surface of each rotor back iron, the magnetic flux flows in the axial direction. In one winding unit (every third of the winding units in the array of winding units) the coil is wound in the opposed direction to the other two. Each coil constitutes one phase. In the figure the winding units 130 are in delta connection to the connection bars 158.1 , 158.2, 158.2 of the phases which is preferably in high-power applications.

[0170] Figure 15 discloses next steps of manufacturing of the rotor assembly 16. After the magnets 17 and the back iron 174 is attached to the rotor ring 172, the surface of the magnets is protected by a barrier cover 176, which in case the practical application of the fluid machine is submerged is a water barrier. The water barrier may be for example fiber reinforced polymer. Ring shaped strip 178 is arranged at radial end of the magnets 17 and the back iron 178 and rims 180 are arranged to cover radial edges of the barrier 176.

[0171] As is disclosed in the figure 16 in the rotor assembly a pair circular arrays of magnets 170.1 , 170.2 supported by the rotor ring 172 are installed on circular main rotor ring 182. This way the main rotor ring 182 of the rotor comprises a first radially and outwardly extending rotor ring 172 extending around the main rotor ring, and a second radially and outwardly extending rotor ring 172 extending around the main rotor ring, axially spaced from each other leaving a space between the rotor rings. More particularly the rotor rings 172 are arranged on axial edges of the main rotor ring 182 magnets facing axially outwards such that an axial gap 184 is formed between the rotor rings 172, substantially in the middle of the rotor ring 172. The axial gap opens radially outwards.

[0172] The gap 184 in the rotor assembly forms a space for axial and radial bearings of the fluid machine. There are two radially extending opposite bearing surfaces 202.1 , 202.2 in the gap which are back walls of the rotor rings 172. The circular main rotor ring has an even outer surface at its radial end in bottom of the gap 184. The surface form axially extending circular bearing surface 206 for radial bearing between the first radially and outwardly extending rotor ring 172 and the second radially and outwardly extending rotor ring 172. The radial bearing comprise one axially extending circular bearing surface 206 and an array of self-positioning pad bearings 208 facing the axially extending circular bearing. Now turning to the figure 17 the axial bearings are formed by arrays of self-positioning pad bearings 208.1 ,208.2 facing to both of the radially extending bearing surfaces 202.1 , 202.2 (see figure 16). There are two arrays of self-positioning pad bearings 208.1 ,208.2 providing support in opposite axial directions, i.e. the first array of self-positioning pad bearings 208.1 providing support in first axial direction and the second array of self-positioning pad bearings 208.2 providing support in second axial direction. The pads in the pad bearings are positionedto cover a whole circle. This way the rotor assembly is rotatably supported by the bearings such that the position of the rotor assembly is always withing a predetermined tolerance.

[0173] According to an aspect of the invention the first circular array of winding units, the second circular array of winding units, the first circular array of magnets and a second circular array of magnets and the first and the second axial bearings are at a same radial distance from a center of rotation of the rotor assembly rendering the assembly thin in radial direction.

[0174] As is disclosed in the figure 17 the stator assembly comprises a bearing support 212 attached to a body 22 of the fluid machine, which bearing support extends radially inwards into the space between the first and the second rotor rings 172, and axial thrust bearing is arranged between the bearing support 212 and the first and the second rotor rings 172. Radial bearing 208 is arranged between the axially extending radial bearing surface 206 of the main rotor ring 182 and radially inner surface of the bearing support 212. The bearing support is generally of T-shaped cross section, having a flange part 212.1 attached to the body 22 of the fluid machine, and a web part 212.2 acting as the bearing support, wherein axial bearings are arranged to both sides of the web part 212.2.

[0175] In the figure 18 a self-positioning bearing pad 210 is disclosed. The views A, B, and C disclose different setups and cross-section views. The self-positioning padded bearing 210 is a hydrodynamic bearing which supports and stabilizes rotating rotor in the fluid machine preferably without a shaft, which should be understood as a component configured to transmit rotational torque, to rotate about is longitudinal axis and being at least twice as long as wide. These reduce effectively friction and accommodate varying load conditions and keep the rotor properly aligned. Self-positioning padded bearing comprises pads supported on a base at a support extension 213 located at or near center of bearing surface of the pad 210 The support extension comprises preferably a round extension from surface of the pad. The support extension has a substantially flat bottom 214 such that the pads capability to pivot about the support extension is limited. The bearing pad 210 is provided with a support cup 216 which has a cavity for accommodating a resilient adaptor 218 substantially corresponding toform of the support extension. Between the support cup 216 and the support extension 213 there is the resilient adaptor 218 arranged. The adaptor 218 allows radial, axial and only moderate pivoting movement of the pad in respect to the support cup 216, in response to changes in load and position of the rotor assembly. The bearing consists of multiple pads, which can compress and accommodate to forces and moment of the rotor assembly independently. The pads are made of materials with good bearing properties to provide a smooth and low- friction surface.

[0176] The support cup 216 is provided with at least three recesses 220, only one of which is shown in the figure 18, which are arranged substantially perpendicularly to bearing surface of the pad 210 in at least two side wall of the support cup 216. Figure 19 discloses how the recesses 220 are used for stabilizing the pads in the bearing support 212. The bearing support 212 is provided with pins 222 which correspond to the form of the recess 220 in the support cup 216. The pins extend from the surface of the bearing support not more than to meet with the thickness of the side wall of the support cup 216. The pins 222 and the recesses 220 are arranged in opposite side walls of the support cup 216 in direction of rotation of the rotor assembly. The pads can individually displace in direction of normal of the pad and pivot under load on a small distance due to a spring-like construction and radially to distribute the load and accommodate manufacturing tolerances and allow moderate stiffness of the frame.

[0177] In the figure 20 a tunnel thruster 300 is shown installed in a marine vessel 302. The marine vessel 302 comprises thruster tunnel 304, which is assembled to a hull 306 of the vessel 302 in transverse direction through the vessel. The shaftless propulsor 10, which is disclosed in the figure 5, is arranged inside the tunnel 304 and attached to the tunnel 304. The propulsor comprises two axial flux electric motors as is depicted in the figure 6, and axial bearings, as is depicted in the figure 17, arranged to same radial position, which considerably decreases overall diameter of the propulsor. Electric connection 310 (see figure 5) to the electric motor is provided through the tunnel 304 in sealed manner. As it can be seen in the figure 5 the blades 18 are directly connected to the rotor assembly. After the propulsor 10 is assembled in the tunnel the thruster 300 is provided with a diffuser sleeve 308 attached to an inner wall of the tunnel on bothaxial side of the propulsor 10. Inner diameter of the tunnel 304 is greater than outer diameter of body 22 of the propulsor. The diffusor sleeves 308 provide smooth transition from inner diameter of the rotor assembly of the propulsor to inner diameter of the tunnel 304.

[0178] With a reference to figure 20 the thruster has a propeller hub 30 positioned to the center axis A of the thruster. The blades 18 of the thruster are connected to the main rotor ring 182 and also to the hub 30 in the middle. The hub functioning as a connection between the blades increasing stiffness of the structure, particularly of the blades.

[0179] In its longitudinal direction, i.e. in the direction of the center axis A, the hub 30 is provided with a first end cap 32, a cylindrical part 34 and a second end cap 36. Tips of the blades are attached to the cylindrical part 34 of the hub 30. The hub 30 is supported only to the blades so it has no direct support e.g. via any bearings from stationary parts, such as the stator assembly, the diffuser sleeves 308 or the tunnel 304 of the thruster. The cylindrical part 34 of the hub 30 is either attached to, for example by bolt joint, or is an integral part of the blades 18, in which case the blades and the cylindrical part 34 of the hub are preferably formed as a casting object. The cylindrical portion 34 is preferably hollow, which makes the hub lighter and its manufacturing consuming less material. It is advantageous if the hub is of light structure therefore the caps, or the caps and the cylindrical part may be of suitable composite material.

[0180] Advantageously wall thickness of hollow cylindrical portion 34 of the hub is substantially equal to thickness of blade root which joins the cylindrical portion of the hub. This makes the structure advantageous in terms of material usage and strength.

[0181] Advantageously cylindrical portion 34 of the hub 30 has diameter which is 10-20% of outer diameter of the thruster. Axial length of the cylindrical portion 34 preferably equals substantially to blade root axial length. The caps 32,36 at the ends of the cylindrical portion 34 are identical, because both of the cap need to operate in an advantageous manner when being a trailing end of the hub. The cup has a first end 32.1 attached to an axial end of the cylindrical portioncylindrical part 34 of the hub. The cup 32 has axial length L which is preferably 0,5-1 , 7 times the diameter of the cylindrical part 34 of the hub 30. This way the hub is of advantageous form and size.

[0182] As a further development of the fluid machine according to the invention shown in the figure 21 the main rotor ring 182 is provided with an access door 314 for maintenance and replacement of bearing pads. This is a feature applicable to all embodiments of the fluid machine, but it is of special importance for submerged marine applications. The access door is a sealed structure withholding also required pressure. Size of the access door makes it possible to service or replace one pad at a time by rotating the access door to position of the pad to be serviced or replaced.

[0183] As a further development of the marine propulsor there is water feeding system 312 provided, which is configured to feed filtered water for the bearing pads. Water feeding system extends into the axial gap 184, more particularly to space between the bearing support 212 and the first and the second rotor rings 172 (see figure 17) where the arrays of bearing pads 208.1 , 208.2 are located. Filtered water, which is substantially free from solid particles, is fed at elevated pressure into the space from which it may purge into the tunnel via gaps between the rotor assembly and the stator assembly. The water feeding system comprises a pump 316 and a filter system 318 to clean and pressurize the water.

[0184] Such a shaftless propulsor, which is a preferred practical application of the fluid machines according the invention, may be successfully used also in other marine propulsor applications, such as a steerable thruster, a manoeuvring thruster, such as a bow or stern thruster, nozzle propeller and a water jet propulsor. Also, a contra-rotating propeller propulsor can be provided by arranging two propulsors 10 co-axially adjacent to one another. With reference to figure 4 the fluid machine is a propulsor for a marine vessel, wherein the blades are connected to the main rotor ring by an axial extension, such as a shaft, which is coupled to the main rotor ring. The body of the propulsor is frame tube which is a sleeve-like body frame and which has a cylindrical outer surface, and which has axial length (L) which is 5 - 15 times of radial thickness of the body frame.

[0185] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is obvious to the skilled person that, along with the technical progress, the basic idea of the invention can be implemented in many ways. The invention and its embodiments are thus not limited to the examples and samples described above but they may vary within the contents of patent claims and their legal equivalents. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.Part list a fluid machine 10 a stator assembly 12 a winding aggregate 13 opening or a space 14 a rotor assembly 16 magnets 17 a blade 18 bearings 20 a body 22 a first circular array of winding units 130.1 a second circular array of winding units 130.2 a winding unit 130 a wire 132 a core 134 core plates 136 a first core plate end 138 a second core plate end 140 a dovetail groove 142 a dovetail key 144 a back face 146 a threaded bolt 148 pin 150a coil 152 a stator frame 154 a radially extending flat portion 156 a power distributor bar 158, 158.1 , 158.2, 158.3. an axially extending portion 160, 162 a first axially opening groove 164 a second axially opening groove 166 a barrier 168 circular array of magnets 170 a first circular array of magnets 170.1 a second circular array of magnets 170.2. rotor ring 172 a back iron 174 a barrier 176 a strip 178 a rim 180 a main rotor ring 182 an axial gap 184 an end flange 186 radially extending axial bearing surfaces 202.1,202.2 self-positioning pad bearings 204.1, 204.2 an axially extending radial bearing surface 206 an array of self-positioning axial pad bearings 208.1 ,208.2 an array of self-positioning radial pad bearings 208 a bearing pad 210 a bearing support 212 a flange part 212.1 a web part 212.2 a support extension 213 a bottom 214 a support cup 216 a resilient adaptor 218 recesses 220 a tunnel thruster 300 a marine vessel 302a tunnel 304 a hull 306 a diffuser sleeve 308 electric connections 310 a water feeding system 312 an access door 314 a pump 316 a filter system 318 a propeller hub 30 a cap 32,34 a first cap end 32.1 second cap end 32.2 a cylindrical part 34 a second end cap 36

Claims

Claims1. A fluid machine (10), comprising a circular stator assembly (12), the stator assembly (12) comprising a winding aggregate (13), a circular rotor assembly (16), the rotor assembly (16) comprising magnets (17) which are configured to the rotor assembly (16) to co-operate with the winding aggregate (13) in the stator assembly (12), and several blades (18) in force transmission connection with the rotor assembly (16), axial and radial bearings (20) configured to support the rotor to the stator assembly (12), characterized in that the winding aggregate (13) comprise a first circular array of winding units(130.1) and a second circular array of winding units (130.2) in the stator assembly (12) axially spaced from each other, and the magnets (17) in the rotor assembly (16) comprise a first circular array of magnets (170.1) and a second circular array of magnets (170.2) and the first circular array of magnets (170.1) is arranged on the axial side of the first circular array of winding units (130.1) and the second circular array of magnets (170.2) is arranged on the axial side of the second circular array of winding units (130.2).

2. A fluid machine (10) according to claim 1 , characterized in that the first circular array of winding units (130.1), the second circular array of winding units(130.2), the first circular array of magnets (170.1) and a second circular array of magnets (170.2) are at a common operational radial distance from a center of rotation the rotor assembly (16).

3. A fluid machine (10) according to claim 1 or 2, characterized in that the first circular array of magnets (170.1) and the second circular array of magnets(170.2) are arranged axially between the first circular array of winding units (130.1) and the second circular array of winding units (130.2).

4. A fluid machine (10) according to claim 1 or 2, characterized in that the first circular array of winding units (130.1) and the second circular array ofwinding units (130.2) are arranged axially between the first circular array of magnets (170.1) and the second circular array of magnets (170.2).

5. A fluid machine (10) according to claim 1 , 2, 3 or 4, characterized in that the fluid machine (10) comprises a body (22) to which the stator assembly (12) is arranged, and the rotor assembly (16) is radially inside the body (22).

6. A fluid machine (10) according to claim 1 , 2, 3 or 4, characterized in that the fluid machine (10) comprises a body (22) to which the stator assembly (12) is arranged, and the rotor assembly (16) is radially outside the body (22).

7. A fluid machine (10) according to anyone of the preceding claims 1 to 5 or anyone of the claims 1 ,2, 3, 4 or 6, characterized in that the rotor assembly (16) comprises a centre axis of rotation defining axial direction and radial direction, and that the axial bearings (20) comprise two radially extending bearing surfaces(202.1.202.2) and an array of self-positioning axial pad bearings (208.1 , 208.2) facing both of the radially extending bearing surfaces, the radial bearings (20) comprise one axially extending circular bearing surface (206) and an array of self-positioning pad bearings (206) facing the axially extending circular bearing surface (206).

8. A fluid machine (10) according to claim 7, characterized in that the first circular array of winding units (130.1) and the second circular array of winding units (130.2), the first circular array of magnets (170.1) and a second circular array of magnets (170.2), and the axial bearings (208.1 ,208.2) are at a same radial distance from a center of rotation the rotor assembly (16).

9. A fluid machine (10) according to claim 4, characterized in that the stator assembly (12) comprises power distributor bars (158,158.1 ,158.2,158.3) for each electric phase, which power distributor bars are arranged between the first circular array of winding units (130.1) and the second circular array of winding units(130.2).

10. A fluid machine (10) according to claim 1 , characterized in that the winding aggregate (13) in the stator assembly (12) is comprised of multiple winding units (130), which comprise a core (134) having a first core plate end (138) at a first end of the core (134) and a second core plate end (140) at second end of the core, opposite to the first end, and a coil (152) arranged on the core wherein the first core plate end (138) is provided with dovetail groove (142) parallel to core plates on its back face.

11. A fluid machine (10) according to claim 10, characterized in that a dovetail key (144), which is provided with attachment means (148), such as at least two threaded bolts and at least one position pin (150) on its back side, is positioned to the dovetail groove of first core plate end (138).

12. A fluid machine (10) according to claim 10 or 11 , characterized in that the first core plate ends (138) are arranged side by side against each other when assembled, forming a back iron so as to close magnetic flux.

13. A fluid machine (10) according to anyone of the preceding claims 1 to 9, characterized in that the winding aggregate (13) comprises a circular stator frame (154), which includes a radially extending flat portion (156), wherein the winding units (130) are attached on a first side of the flat portion (156), and that the stator assembly (12) comprises power distributor bars(158.158.1.158.2.158.3) for each electric phase, each of which power distributor bars is attached on a second side of the flat portion (156).

14. A fluid machine (10) according to claim 13, characterized in that the power distributor bars (158,158.1 ,158.2,158.3) are of different diameters and the winding wires of winding units (130) are guided axially through the flat portion (156) of the stator frame (154) radially between the power distributor bar (158.1) having the greatest diameter of the distributor bars and the power distributor bar(158.3) having the smallest diameter of the distributor bars.

15. A fluid machine (10) according to claim 13 or 14, characterized in that the circular stator frame (154) comprises an axially extending portion (160, 162) at radially outer edge and radially inner edge of the radially extending flat portion (156), which axially extending portions (160,162) extends axially to bothdirections from the radially extending flat portion (156), forming a first axially opening groove (164) in the stator frame and a second axially opening groove (166) in the stator frame, wherein the winding units (130) are arranged in the first axially opening groove (164) and the distributor bars (158,158.1 ,158.2,158.3) are arranged in the second axially opening groove (160).

16. A fluid machine (10) according to claim 15, characterized in that the first axially opening groove (158) is provided with a barrier covering the groove.

17. A fluid machine (10) according to claim 15 or 16, characterized in that the second axially opening groove (160) is filled with insulation material.

18. A fluid machine (10) according to claim 4 and anyone of the preceding claim 13 to 17, characterized in that the first circular array of winding units (130.1) is attached to a first circular stator frame (154) and a second circular array of winding units (130.2) is attached to a second circular stator frame (154), wherein the stator frames are arranged their winding units facing each other.

19. A fluid machine (10) according to claim 8, 9, or 10, characterized in that the pair of the circular stator frames (154) and the winding units (130) attached to the frames (154) are assembled inside a body (22) of the fluid machine (10).

20. A fluid machine (10) according to anyone of the preceding claims, characterized in that the magnets (17) in the rotor assembly are permanent magnets.

21. A fluid machine (10) according to claim 7, characterized in that the rotor assembly (16) comprises a circular main rotor ring (182), and the first circular array of magnets (170.1) and the second circular array of magnets (170.2) are arranged radially outside the main rotor ring (182), both at the common operational radial distance, such that magnetic flux is substantially axial.

22. A fluid machine (10) according to claim 21 , characterized in that the main rotor ring (182) comprises a first radially and outwardly extending rotor ring (172) and a second radially and outwardly extending rotor ring (172), axially at a distance from each other, wherein the first circular array of magnets (170.1) is attached to the first radially and outwardly extending rotor ring (172), and thesecond circular array of magnets (170.2) is attached to the second radially and outwardly extending rotor ring (172).

23. A fluid machine (10) according to claim 22, characterized in that the rotor rings (172) are axially spaced from each other leaving a space between the rotor rings, wherein the first circular array of magnets (170.1) is arranged to an axial outer face of the first rotor ring (172), opposite to the space, and the second circular array of magnets (170.2 ) is arranged to an axial outer face of the second rotor ring, opposite to the space.

24. A fluid machine (10) according to anyone of the preceding claims 21 to 23, characterized in that the main rotor ring (182) of the rotor assembly (16) comprises a first radially and outwardly extending rotor ring (172) extending around the main rotor ring (182), and a second radially and outwardly extending rotor ring (172) extending around the main rotor ring (182), axially spaced from each other leaving a space between the rotor rings (172), and the stator assembly (12) comprises a bearing support (212) attached the body (22) of the fluid machine (10), which bearing support extends radially inwards into the space between the first and the second rotor ring (172), and that axial thrust bearing (20) is arranged between the bearing support (212) and the first and the second rotor ring (172).

25. A fluid machine (10) according to claim 24, characterized in that the main rotor ring (182) of the rotor assembly comprises a axially extending radial bearing surface (206) between the first radially and outwardly extending rotor ring (172) and the second radially and outwardly extending rotor ring (172), and that radial bearing is arranged between the axially extending radial bearing surface (206) of the main rotor ring (182) and radially inner surface of the bearing support (212).

26. A fluid machine (10) according to claim 24 or 25, characterized in that the bearing comprises a self-positioning padded bearing (208.1 ,208.2).

27. A fluid machine (10) according to claim 24, 25 or 26, characterized in that the bearing support (212) is of T-shaped cross section, having a flange part (212.1) attached to the body (22) of the fluid machine (10), and a web part (212.2) wherein axial bearings are arranged to both sides of the web part (212.2).

28. A fluid machine (10) according to claim 1 , characterized in the fluid machine comprises two electromechanical machine assemblies assembled axially spaced from each other.

29. A fluid machine (10) according to claim anyone of the preceding claims, characterized in that the fluid machine (10) is a shaftless propulsor for a marine vessel, wherein the blades (18) are directly connected to the main rotor ring (182).

30. A fluid machine (10) according to claim 29, characterized in that the blades (18) are connected to the main rotor ring (182) by an axial extension, such as a shaft, which is coupled to the main rotor ring (182).

31. A fluid machine (10) according to claim anyone of the preceding claims 29 to 30, characterized in that a water feeding system (312) is provided to the propulsor, which is configured to feed filtered water for the bearing pads (210).

32. A fluid machine (10) according to anyone of the preceding claims 29 to 30, characterized in that a body (22) of the propulsor has a cylindrical outer surface, and which has axial length (L) which is 5 - 15 times of radial thickness of the body (22).

33. A fluid machine (10) according to anyone of the preceding claims 29 to 30, characterized in that a body (22) of the propulsor has a cylindrical form having a first diameter, and the main rotor ring (182) has a second diameter, wherein ratio of the first diameter to difference between the first and the second diameter is 8 - 12.

34. A fluid machine (10) according to anyone of the preceding claims 29 to33, characterized in that the blades (18) of the thruster are connected to the main rotor ring (182) and to a propeller hub (30) arranged to the center axis A of the thruster, wherein the hub (30) is supported only to the blades (18).

35. A fluid machine (10) according to anyone of the preceding claims 28 to34, characterized in that the hub (30) has diameter which is 10-20% of outer diameter of the thruster (10).

36. A propulsion system for a marine vessel, comprising a fluid machine (10) according to anyone of the preceding claims 1 to 35, configured to generate thrust to move the vessel through water.

37. A turbine for converting fluid energy into electricity, comprising a fluid ma- chine (10) according to anyone of the preceding claims 1 to 28.

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