A contra-rotating propeller electric propeller driven by an axial flux motor

Abstract

The present invention relates to a counter-rotating propeller electric propulsion device driven by an axial flux motor, comprising a propeller unit, wherein the propeller unit comprises: a housing, an axial flux motor, a propeller and a bearing assembly, wherein a forward propeller unit and a reverse propeller unit are coaxially arranged in parallel front and back, and the propeller of the forward propeller unit and the propeller of the reverse propeller unit have opposite rotation directions, and are used to generate thrust in the same direction. The present invention reduces the intermediate transmission loss between the motor and the propeller, and has the characteristics of improving efficiency, simplifying the structure of the propulsion system, reducing noise and vibration, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship propulsion devices, and in particular relates to a counter-rotating propeller electric propulsion device driven by an axial flux motor. Background Art

[0002] With the development of electric propulsion technology, electric propulsion systems are increasingly used in ships. Common electric propulsion systems include variable speed gearboxes, shaft systems (including shafts, couplings, various bearings and bearing seats, stern tube seals), propellers, etc. The propulsion method of the electric propulsion system is that the motor drives the variable speed gearbox to decelerate, and then drives the shaft system and propeller to rotate, generating thrust for the ship to move forward or backward. This propulsion method has the following problems: complex structure, many parts, high failure rate, large space occupation, and heavy weight; low propulsion efficiency: the motor and propeller are transmitted through gears, shaft systems and other components, and the gear meshing produces energy loss. At the same time, the bearings are usually sliding bearings with large friction and high friction power consumption; the above transmission links produce intermediate transmission losses, reducing the propulsion efficiency of the system; the transmission gear meshing produces vibration and causes noise. Secondly, after the water flows through the shaft system and underwater appendages, turbulence is generated, and the propeller rotates in the turbulent flow, generating excitation and cavitation, and the cavitation bursts to produce noise. Summary of the invention

[0003] In order to reduce the intermediate transmission loss between the motor and the propeller, improve efficiency, simplify the propulsion system structure, reduce noise and vibration, etc., the present invention proposes a counter-rotating annular electric propeller driven by axial flux motors arranged in front and behind. This adopts an axial flux motor placed in the water to directly drive the counter-rotating propeller to rotate, eliminating the intermediate transmission equipment, and the rotor and propeller assembly are supported by bearings placed in the water and transmit the thrust to the motor and the hull.

[0004] In order to solve at least one of the above technical problems, the technical solution adopted by the present invention is:

[0005] An axial flux motor driven counter-rotating propeller electric propeller comprises a propeller unit, wherein the propeller unit comprises: a housing, an axial flux motor, a propeller and a bearing assembly, wherein:

[0006] The axial flux motor comprises: an end face flange, a rotor assembly and two stator assemblies, the end face flanges are respectively provided at both ends of the housing, the two stator assemblies are respectively fixed to the end face flanges at both ends, the rotor assembly is arranged between the two stator assemblies and the air gap magnetic field direction generated by the two stator assemblies is axial; the propeller is connected to the rotor assembly through the blade tip flange; the bearing assembly comprises: a thrust bearing and a radial bearing, the thrust bearing is connected to one end of the blade tip flange and is located outside the end face flange, and the radial bearing is arranged between the end face flange and the blade tip flange;

[0007] The forward-rotating propeller unit and the reverse-rotating propeller unit are coaxially arranged in parallel front and back, and the propeller of the forward-rotating propeller unit and the propeller of the reverse-rotating propeller unit have opposite rotation directions and are used to generate thrust in the same direction.

[0008] Furthermore, the rotor assembly includes: a permanent magnet and a support frame, the permanent magnet is embedded in the support frame, the support frame is arranged parallel to the stator assembly, and one end of the support frame is connected to the blade tip flange.

[0009] Furthermore, it also includes a protective cover connected to the shell.

[0010] Furthermore, the thrust bearing of the forward rotation propeller unit is located between the end face flange of the forward rotation propeller unit and the protective cover, and the thrust bearing of the forward rotation propeller unit and the inner end face of the protective cover form a forward thrust bearing pair, and the thrust bearing of the forward rotation propeller unit and the end face flange of the forward rotation propeller unit form a reverse thrust bearing pair.

[0011] Furthermore, the thrust bearing of the reversing propeller unit is located between the end face flange of the forward rotation propeller unit and the end face flange of the reversing propeller unit, and the thrust bearing of the reversing propeller unit and the end face flange of the forward rotation propeller unit form a forward thrust bearing pair, and the thrust bearing of the reversing propeller unit and the end face flange of the reversing propeller unit form a reverse thrust bearing pair.

[0012] Furthermore, the radial bearings are coaxially arranged on the end face flanges at both ends, and the radial bearings and the outer cylindrical surface of the blade tip flange constitute a radial bearing pair to support the weight of the rotor assembly and the propeller, and to withstand the centrifugal force generated by eccentricity during the rotation of the rotor assembly and the propeller.

[0013] Furthermore, water grooves are provided on the surfaces of the radial bearing pair, the forward thrust bearing pair and the reverse thrust bearing pair for accommodating mud and sand in the water and cooling them by water flow.

[0014] Furthermore, the thrust bearing and radial bearing are both made of corrosion-resistant and wear-resistant metal or non-metal materials, or polymer materials, or hard wear-resistant coatings.

[0015] Furthermore, the thrust bearing uses paired permanent magnets or electromagnetic coils with the same polarities repelling each other to form a magnetic thrust bearing pair.

[0016] Furthermore, the propeller is an integral propeller or a split propeller.

[0017] Furthermore, the counter-rotating propeller unit comprises a plurality of the propeller units connected in series.

[0018] The beneficial effects of the present invention include at least:

[0019] 1) Improved propulsion efficiency: First, an axial flux permanent magnet brushless motor (disc motor) with a dual-stator single-rotor structure is used, which has high motor efficiency; second, the motor rotor directly drives the propeller to rotate, and no intermediate transmission link is required, which reduces transmission losses; third, the counter-rotating propeller type is adopted, and the rear propeller absorbs the circumferential rotating eddy current energy of the front propeller, further improving efficiency;

[0020] 2) High power density: Dual motors are used, and each motor has a dual-stator single-rotor structure. The magnetic fields on both sides of the rotor generate electromagnetic force to drive the rotor, and output power at the same time, with high power density;

[0021] 3) Reduced noise and vibration: Since the rotor directly drives the propeller, the vibration and noise caused by the gear meshing of the gearbox in traditional propulsion types are eliminated;

[0022] 4) Simpler structure, improved reliability, and less space occupied in the cabin: The motor directly drives the propeller, eliminating the intermediate transmission link, making the structure simpler and more reliable. In addition, since the motor is placed underwater, space in the cabin is saved;

[0023] 5) Achieve higher power and thrust through the combination of multi-stage thrusters. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the propeller structure of the present invention.

[0025] Figure 2 for Figure 1 Cross-sectional view along the line CC of the first embodiment.

[0026] Figure 3 for Figure 2 A partial enlarged view of .

[0027] Figure 4 It is a schematic diagram of the structure of the integrated propeller of the present invention.

[0028] Figure 5 It is a schematic diagram of the split propeller structure of the present invention.

[0029] Figure 6 for Figure 1 A cross-sectional view taken along the line CC of the second embodiment.

[0030] Among them, 1. front propeller, 2. front radial bearing, 3. front thrust bearing, 4. front protective cover, 5. front motor front end face flange, 6. front motor double stator assembly, 7. front motor single rotor assembly, 8. front motor casing, 9. front motor rear end face flange, 10. rear motor front end face flange, 11. rear thrust bearing, 12. rear motor single rotor assembly, 13. rear motor double stator assembly, 14. rear motor rear end face flange, 15. rear protective cover, 16. rear radial bearing, 17. rear propeller, 18. blade tip flange, 19. first stage thruster unit, 20. second stage thruster unit, 21. third stage thruster unit. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0032] Embodiment 1: In this embodiment, the present invention is composed of two propeller units arranged in front and behind, see Figure 1-3 As shown, the forward (front) propeller unit and the reverse (rear) propeller unit are coaxially arranged in parallel front and back, and each propeller unit includes a housing, an axial flux motor (disc motor), a propeller and a bearing assembly. Each motor is independently controlled by a controller, and each drives a propeller with opposite rotation directions and consistent thrust directions, forming counter-rotating propellers arranged front and back. The rear propeller absorbs the circumferential rotating eddy current energy of the front propeller, thereby improving the propulsion efficiency. The motor type is a dual-stator single-rotor axial flux permanent magnet brushless motor (disc motor), which directly drives the propeller to rotate, and the propeller thrust is transmitted to the motor through the bearing group, and finally pushes the hull.

[0033] It can be understood that in this embodiment of the present invention, two motors are arranged in series front and back, coaxially, and each drives a propeller. The front propeller rotates forward, and the rear propeller rotates reversely. The rotation directions of the front and rear propellers are opposite, and the thrust directions are consistent. The rear propeller absorbs the circumferential rotating vortex energy of the front propeller to form a counter-rotating propeller, which improves the propulsion efficiency. The blade parameters such as the number of blades and pitch distribution of the front and rear propellers need to be determined through hydrodynamic optimization design.

[0034] The present invention adopts an axial flux permanent magnet brushless motor (disc motor) which is different from ordinary motors. Its air gap is planar, the direction of the air gap magnetic field is axial, the current-carrying conductor system is placed radially, and the stator assembly and the rotor assembly are disc structures. The motor is composed of a stator assembly, a rotor assembly, a housing, and an end face flange. In the present invention, the front and rear motors are both double-stator single-rotor structures. In each motor, two stator assemblies are respectively fixed on the front and rear end face flanges of the motor, and a single rotor assembly is in the middle. The motor stator assembly is composed of an axial iron core and a coil, and can also be designed as a coreless structure. The stator is integrally encapsulated with a multi-layer sealing insulation filling protective material to isolate it from water and play an insulating role. The rotor assembly is sandwiched between the two stator assemblies and is parallel to the stator assembly, rather than a radially concentric structure with the stator like an ordinary motor. The rotor assembly contains a permanent magnet and a support frame, the permanent magnet is embedded in the support frame, and the support frame is encapsulated with a sealing insulation filling material to prevent water from entering the interior and corroding the permanent magnet. The housing is the thruster housing, and the left and right ends of the housing are connected to the end face flanges of the motor.

[0035] The rotor assembly of the present invention has a large inner diameter and can accommodate a propeller. The propeller is fixed on the blade tip flange, and the blade tip flange is connected to the inner diameter of the rotor support frame. The rotor directly drives the propeller to rotate, and the motor speed is the propeller speed, and no intermediate transmission links such as gears are required. The left and right stators of the motor generate a rotating magnetic field after a three-phase power supply is connected, and the permanent magnets in the middle rotor assembly generate electromagnetic force under the action of the rotating magnetic field. The rotor rotates and outputs torque, and the propeller generates thrust to propel the ship after rotating in the water.

[0036] The propeller of the present invention is a metal propeller or a composite propeller. The number of propeller blades is determined according to the calculation of hydrodynamic performance, and the number of blades can be 2, 3, 4, 5, 6 or more. The number of front and rear propellers can be inconsistent to reduce vibration and improve efficiency.

[0037] like Figure 4 As shown, the propeller can be an integral type, with each blade connected to a common blade tip flange as a whole, and then connected to a rotor support frame through the blade tip flange.

[0038] like Figure 5 As shown, the propeller blades can also be split, and each blade is fixed to the inner circle of the rotor support frame through a blade tip flange, supported and directly driven by the rotor. At the same time, since the propeller is made into a split type, it is also convenient for disassembly and replacement.

[0039] Whether it is an integral propeller or a split propeller, both are hubless propellers. Each blade is connected to the rotor through a blade tip flange and is directly driven by the rotor. The motor speed is the propeller speed. There is no need for a shaft system and hub for support and transmission, nor is there a need for intermediate transmission links such as transmission gears.

[0040] Each motor and the propeller it drives are equipped with a set of bearing assemblies. The bearing assemblies are water-lubricated bearings that bear the weight of the rotor assembly and the propeller, as well as the forward and reverse thrust of the propeller. Each set of bearing assemblies consists of a thrust bearing and a radial bearing: the thrust bearing is connected to one end of the blade tip flange and is located outside the end face flange, and the radial bearing is arranged between the end face flange and the blade tip flange.

[0041] More specifically: the radial bearings are coaxially arranged on the end face flanges at both ends, and the two coaxial radial bearings and the outer cylindrical surface of the blade tip flange form a radial bearing pair to support the weight of the rotor assembly and the propeller, and bear the centrifugal force formed by the eccentricity during the rotation of the rotor assembly-propeller. A thrust bearing is connected to the blade tip flange. In the front propeller unit: the thrust bearing and the end face of the protective cover form a forward thrust bearing pair, and the thrust bearing and the front end face flange form a reverse thrust bearing pair to bear the forward and reverse thrust generated by the forward and reverse rotation of the front propeller; in the rear propeller unit: the thrust bearing and the rear end face flange of the front motor form a forward thrust bearing pair, and the thrust bearing and the front end face flange of the rear motor form a reverse thrust bearing pair to bear the forward and reverse thrust generated by the forward and reverse rotation of the rear propeller.

[0042] Both thrust bearings and radial bearings are made of corrosion-resistant and wear-resistant metal or non-metal materials, or polymer materials, or hard wear-resistant coatings, etc. The protective cover and motor flange end faces that rub against them are also sprayed with wear-resistant coatings or equipped with wear-resistant sleeves.

[0043] The thrust bearing may even use paired permanent magnets or electromagnetic coils with the same poles repelling each other to form a magnetic thrust bearing pair. The magnetic thrust formed by the repulsion can bear the weight of the rotor assembly and the propeller, while bearing the forward and reverse thrust of the propeller. In addition, it can also reduce contact friction, reduce losses, and extend service life.

[0044] The surfaces of the radial bearing pair and the thrust bearing pair may be provided with water grooves for containing mud and sand in the water and cooling the bearing pair through water flow.

[0045] The front protective cover is installed at the front end of the front motor, and the rear protective cover is installed at the rear end of the rear motor. They play the role of protecting the motor and the rotating thrust plate and bearing the thrust of the propeller. The front and rear protective covers can be made into arc or streamlined shapes, which is beneficial to reduce resistance and improve hydrodynamic performance.

[0046] Embodiment 2: In this embodiment of the present invention, each axial flux motor and its propeller and bearing form an independent, modular propeller unit, so that multiple propeller units can be connected in series to form a multi-stage linkage propeller combination. Each time a set of propeller units is added, it is only necessary to fasten the front face flange of the propeller unit to the rear face flange of the previous stage propeller unit, and then assemble the rear protective cover on the rear face flange of the last stage propeller unit. That is, not only can the counter-rotating propellers be composed of two sets of propeller units, but also can be formed by three sets of propeller units. Figure 6 The three-stage propeller shown, the four-stage propeller formed by four sets of propeller units, and the five-stage, six-stage, seven-stage, etc., can achieve greater power and thrust through the combination of multi-stage propellers. Of course, in order to improve the hydrodynamic performance, the propeller of each stage of the propeller unit needs to be hydrodynamically optimized and calculated, and the propellers of each stage of the propeller unit will be different.

[0047] In summary, the present invention eliminates all transmission links between the motor and the propeller in the electric propulsion system, and the motor directly drives the propeller, which has high efficiency, simple structure and high reliability; two motors are used to drive counter-rotating propellers or multiple motors are used to drive more propellers, which improves efficiency and has high power density. The motor adopts an axial flux motor with a double-stator single-rotor structure, which has high power density and efficiency and low operating noise. In addition, the motor is placed underwater, which reduces the space occupied in the cabin and improves the utilization rate of the cabin space. It is suitable for use on various electric ships.

[0048] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "front", "rear", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0049] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention. At the same time, a person skilled in the art may make changes in the specific implementation methods and scope of application based on the ideas of the present application.

Claims

1. An axial flux motor driven counter-rotating propeller electric propeller, characterized in that: The invention comprises a propeller unit, wherein the propeller unit comprises: a housing, an axial flux motor, a propeller and a bearing assembly, wherein: The axial flux motor comprises: an end face flange, a rotor assembly and two stator assemblies, the two ends of the shell are respectively provided with the end face flanges, the two stator assemblies are respectively fixed on the end face flanges at the two ends, the rotor assembly is arranged between the two stator assemblies and the air gap magnetic field direction generated by the two stator assemblies is axial; the propeller is connected to the rotor assembly through the blade tip flange; the bearing assembly comprises: a thrust bearing and a radial bearing, the thrust bearing is connected to one end of the blade tip flange and is located on the outside of the end face flange, and the radial bearing is arranged between the end face flange and the blade tip flange; the rotor assembly comprises: a permanent magnet and a support frame, the permanent magnet is embedded in the support frame, the support frame is arranged parallel to the stator assembly, and one end of the support frame is connected to the blade tip flange; The forward propeller unit and the reverse propeller unit are coaxially arranged in parallel front and back, and the propeller of the forward propeller unit and the reverse propeller unit have opposite rotation directions, and are used to generate thrust in the same direction; It also includes a protective cover connected to the shell; the thrust bearing of the forward-rotating propeller unit is located between the end face flange of the forward-rotating propeller unit and the protective cover, and the thrust bearing of the forward-rotating propeller unit and the inner end face of the protective cover form a forward-rotating thrust bearing pair, and the thrust bearing of the forward-rotating propeller unit and the end face flange of the forward-rotating propeller unit form a reverse-rotating thrust bearing pair; The thrust bearing of the reverse propeller unit is located between the end face flange of the forward propeller unit and the end face flange of the reverse propeller unit, and the thrust bearing of the reverse propeller unit and the end face flange of the forward propeller unit form a forward thrust bearing pair, and the thrust bearing of the reverse propeller unit and the end face flange of the reverse propeller unit form a reverse thrust bearing pair; The radial bearings are coaxially arranged on the end face flanges at both ends, and the radial bearings and the outer cylindrical surface of the blade tip flange constitute a radial bearing pair to support the weight of the rotor assembly and the propeller, and to withstand the centrifugal force formed by eccentricity during the rotation of the rotor assembly and the propeller.

2. The contra-rotating propeller electric propeller according to claim 1, characterized in that: The surfaces of the radial bearing pair, the forward thrust bearing pair and the reverse thrust bearing pair are provided with water grooves for containing mud and sand in the water and cooling them by water flow.

3. The contra-rotating propeller electric propeller according to claim 1, characterized in that: The thrust bearing and radial bearing are both made of corrosion-resistant and wear-resistant metal or non-metal material, or polymer material, or hard wear-resistant coating.

4. The contra-rotating propeller electric propeller according to claim 1, characterized in that: The thrust bearing adopts paired permanent magnets or electromagnetic coils with the same poles repelling each other to form a magnetic thrust bearing pair.

5. The contra-rotating propeller electric propeller according to claim 1, characterized in that: The propeller is an integral propeller or a split propeller.

6. The contra-rotating propeller electric propeller according to any one of claims 1 to 5, characterized in that: The counter-rotating thruster unit comprises a plurality of the thruster units connected in series.

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