Toroidal propeller

Abstract

Provided is a toroidal propeller that is rotationally driven about a central axis, said toroidal propeller comprising a hub which extends in an axial direction along the central axis and loop-shaped blades which are provided outward of the hub in the radial direction intersecting the axial direction. The blades each integrally include: a first curved blade part that extends outwardly in the radial direction in a curved manner from a first base end part which is positioned inward in the radial direction; a second curved blade part that extends outwardly in the radial direction in a curved manner from a second base end part which is provided at a different position inward in the radial direction from the first base end part, and that is provided so as to be separate from the first curved blade part in at least one of the axial direction and the circumferential direction about the central axis; and a blade end part that, at the outermost side in the radial direction, connects a first tip end part on the radially outer side of the first curved blade part and a second tip end part on the radially outer side of the second curved blade part. The first base end part and the second base end part are disposed at differing positions in the radial direction.

Description

Toroidal Propeller

[0001] This disclosure relates to a toroidal propeller. This application claims priority to Japanese Patent Application No. 2025-019165, filed in Japan on February 7, 2025, the content of which is incorporated herein by reference.

[0002] Patent Document 1 discloses a toroidal propeller including a hub (central axis) extending in the central axis direction and a loop-shaped blade (blade) extending radially outward from the hub.

[0003] Japanese Patent No. 6140296

[0004] However, in a toroidal propeller having a configuration as described in Patent Document 1, further improvement in propeller performance, such as efficiency improvement and noise reduction, is desired.

[0005] This disclosure has been made to solve the above problems, and an object thereof is to provide a toroidal propeller capable of further improving propeller performance. [[ID=十七]]

[0006] To solve the above problems, the toroidal propeller according to this disclosure is a toroidal propeller that is rotationally driven around a central axis. The toroidal propeller includes a hub and a loop-shaped blade. The hub extends in the axial direction along the central axis. The blade is provided on the outer side in the radial direction intersecting the axial direction with respect to the hub. The blade integrally includes a first curved blade portion, a second curved blade portion, and a blade end portion. The first curved blade portion curves and extends from a first proximal end portion located on the inner side in the radial direction toward the outer side in the radial direction. The second curved blade portion curves and extends from a second proximal end portion provided at a position different from the first proximal end portion on the inner side in the radial direction toward the outer side in the radial direction. The second curved blade portion is provided at a distance from the first curved blade portion in at least one of the axial direction and the circumferential direction around the central axis. The blade end portion is on the outermost side in the radial direction and connects a first tip portion on the outer side in the radial direction of the first curved blade portion and a second tip portion on the outer side in the radial direction of the second curved blade portion. The first proximal end portion and the second proximal end portion are arranged at different positions in the radial direction.

[0007] The toroidal propeller according to this disclosure is a toroidal propeller that is rotationally driven about a central axis. The toroidal propeller comprises a hub and a loop-shaped blade. The hub extends axially along the central axis. The blade is provided radially outward from the hub, intersecting the axial direction. The blade integrally comprises a first curved blade section, a second curved blade section, and a blade tip. The first curved blade section curves outward from a first base end located radially inward. The second curved blade section curves outward from a second base end located radially inward at a different position from the first base end. The second curved blade section is provided at least one distance from the first curved blade section in the axial direction and in the circumferential direction about the central axis. The wingtip connects the first radially outer tip of the first curved wing section and the second radially outer tip of the second curved wing section at the outermost radial point. The first curved wing section has a first forward curved section and a first rearward curved section. The first forward curved section curves to one side in the circumferential direction of the wing around the central axis. The first rearward curved section is provided radially inward or outward relative to the first forward curved section. The first rearward curved section curves to the other side in the circumferential direction. The second curved wing section has a second rearward curved section and a second forward curved section. The second rearward curved section curves to the other side in the circumferential direction so as to move away from the first forward curved section to the other side in the circumferential direction. The second forward curved section curves to one side in the circumferential direction so as to move away from the first rearward curved section to one side in the circumferential direction.

[0008] The toroidal propeller according to this disclosure is a toroidal propeller that is rotationally driven about a central axis. The toroidal propeller comprises a hub and a loop-shaped blade. The hub extends axially along the central axis. The blade is provided radially outward from the hub, intersecting the axial direction. The blade integrally comprises a first curved blade section, a second curved blade section, and a blade tip. The first curved blade section curves outward from a first base end located radially inward. The second curved blade section curves outward from a second base end located radially inward at a different position from the first base end. The second curved blade section is provided at least one distance from the first curved blade section in the axial direction and in the circumferential direction about the central axis. The wingtip connects the radially outermost first tip of the first curved wing section and the radially outer second tip of the second curved wing section at the radially outermost point. The first curved wing section, with respect to the first base end and the first tip, has a first intermediate wing section between the first base end and the first tip that curves rearward in the direction of rotation of the wing around the central axis. The second curved wing section, with respect to the second base end and the second tip, has a second intermediate wing section between the second base end and the second tip that curves rearward in the direction of rotation of the wing around the central axis.

[0009] The toroidal propeller of this disclosure makes it possible to further improve propeller performance.

[0010] This is a perspective view showing a toroidal propeller according to the first embodiment of this disclosure. This is a view of the toroidal propeller according to the first embodiment of this disclosure from the axial direction. This is a view of the toroidal propeller according to the first embodiment of this disclosure from the radially outward direction. This is a diagram showing the configuration of a toroidal propeller according to another modification of the first embodiment of this disclosure. This is a diagram showing the configuration of a toroidal propeller according to the second embodiment of this disclosure. This is a diagram showing the configuration of a toroidal propeller according to the third embodiment of this disclosure. This is a diagram showing the configuration of a toroidal propeller according to the fourth embodiment of this disclosure.

[0011] Hereinafter, a toroidal propeller according to an embodiment of the present disclosure will be described with reference to Figures 1 to 7. <First Embodiment> (Configuration of Toroidal Propeller) As shown in Figures 1 to 3, the toroidal propeller 1A comprises a hub 2A and a plurality of blades 3A. The toroidal propeller 1A is attached to an external mounting object 100 (see Figure 3). Examples of mounting objects 100 include a drive shaft that is provided on a ship, an underwater vehicle, an underwater drone, etc., and is driven by a drive source such as a motor or engine.

[0012] The hub 2A extends in the axial direction Da along the central axis O. In this embodiment, the hub 2A is formed in a frustoconical shape in which the diameter in the radial direction Dr intersecting the axial direction Da gradually decreases from the end 2a of the first side Da1 in the axial direction Da to the end 2b of the second side Da2 in the axial direction Da. In this embodiment, the entire axial direction Da of the hub 2A is a reduced diameter section 22 in which the diameter gradually decreases from the first side Da1 to the second side Da2 in the axial direction Da. The end 2a of the second side Da2 in the axial direction Da of the hub 2A is connectable to an external mounting target 100.

[0013] Multiple blades 3A are provided on the outside of the hub 2A in the radial direction Dr, intersecting the axial direction Da. Multiple blades 3A are provided at intervals in the circumferential direction Dc around the central axis O. In this embodiment, for example, three sets of blades 3A are provided. The number of blades 3A may be two sets, or four or more sets may be provided.

[0014] Each of the multiple wings 3A is formed in a loop shape. Specifically, each wing 3A integrally comprises a first curved wing section 31A, a second curved wing section 32A, and a wingtip 33A.

[0015] The first curved wing portion 31A has a first base portion 311A ​​located on the inside in the radial direction Dr and a first tip portion 312A located on the outside in the radial direction Dr.

[0016] The first base end 311A ​​is connected to the outer circumferential surface of the reduced diameter portion 22 of the hub 2A. The first curved wing portion 31A curves outward from the first base end 311A ​​toward the first tip portion 312A in the radial direction Dr. The first intermediate portion 313A between the first base end 311A ​​and the first tip portion 312A is curved to protrude from the first base end 311A ​​and the first tip portion 312A in at least one of the axial direction Da and the circumferential direction Dc.

[0017] The second curved wing portion 32A is provided at least one of the axial direction Da and the circumferential direction Dc relative to the first curved wing portion 31A. The second curved wing portion 32A has a second base portion 321A located on the inside in the radial direction Dr and a second tip portion 322A located on the outside in the radial direction Dr.

[0018] The second base end 321A is located at a different position from the first base end 311A. In this embodiment, the second base end 321A is located at a different position in the axial direction Da relative to the first base end 311A. The second base end 321A is connected to the outer circumferential surface of the reduced diameter portion 22 of the hub 2A. The second curved wing portion 32A curves outward from the second base end 321A toward the second tip portion 322A in the radial direction Dr. The second intermediate portion 323A between the second base end 321A and the second tip portion 322A is curved to protrude from the second base end 321A and the second tip portion 322A in at least one of the axial direction Da and the circumferential direction Dc. The second intermediate portion 323A of the second curved wing portion 32A is curved away from the first intermediate portion 313A of the first curved wing portion 31A in at least one of the axial direction Da and the circumferential direction Dc.

[0019] The wingtip 33A is located at the outermost point in the radial direction Dr of the wing 3A. The wingtip 33A connects the first tip 312A of the first curved wing section 31A and the second tip 322A of the second curved wing section 32A.

[0020] The hub 2A has a first wing support portion 23A to which the first base end portion 311A ​​is connected, and a second wing support portion 24A to which the second base end portion 321A is connected. The first wing support portion 23A and the second wing support portion 24A are formed in the reduced diameter portion 22 of the hub 2A. As shown in Figure 3, the first wing support portion 23A of the hub 2A has a first diameter dimension D1. The second wing support portion 24A of the hub 2A is formed on the second side Da2 in the axial direction Da relative to the first wing support portion 23A, and has a second diameter dimension D2 which is smaller than the first diameter dimension D1. As a result, the first base end portion 311A ​​connected to the first wing support portion 23A and the second base end portion 321A connected to the second wing support portion 24A are positioned at different locations in the radial direction Dr.

[0021] (Effects) In the toroidal propeller 1A of the above embodiment, the first base end 311A ​​of the first curved blade section 31A and the second base end 321A of the second curved blade section 32A, which constitute the loop-shaped blade 3A, are positioned at different locations in the radial direction Dr. Therefore, when the toroidal propeller 1A is rotated around the central axis O, the vortex (hub vortex) Sa generated around the first base end 311A ​​of the first curved blade section 31A and the vortex Sb (hub vortex) generated around the second base end 321A of the second curved blade section 32A are at different locations in the radial direction Dr. Consequently, the superposition of the vortex Sa generated around the first base end 311A ​​of the first curved blade section 31A and the vortex Sb generated around the second base end 321A of the second curved blade section 32A, which increases the effect of vortices, is suppressed. Therefore, the effects of vortices Sa and Sb generated around the hub 2A during the rotation of the toroidal propeller 1A can be suppressed, thereby improving efficiency and reducing noise. As a result, further improvements in propeller performance can be achieved.

[0022] Furthermore, in the above embodiment, the hub 2A has a first wing support portion 23A having a first diameter dimension D1 to which the first base end portion 311A ​​is connected, and a second wing support portion 24A having a second diameter dimension D2 smaller than the first diameter dimension D1 to which the second base end portion 321A is connected. Therefore, the first base end portion 311A ​​of the first curved wing portion 31A and the second base end portion 321A of the second curved wing portion 32A can be connected to the hub 2A at different positions in the radial direction Dr. Furthermore, since the second wing support portion 24A is formed on the second side Da2 in the axial direction Da relative to the first wing support portion 23A, the rotation of the toroidal propeller 1A causes the fluid (water) to flow from the first side Da1 to the second side Da2 in the axial direction Da. As a result, the influence of vortices Sa generated around the first base end portion 311A ​​on the upstream side in the fluid flow direction (first side Da1 in the axial direction Da) may extend to vortices Sb generated around the second base end portion 321A on the downstream side in the flow direction (second side Da2 in the axial direction Da). In contrast, since the first base end portion 311A ​​of the first curved wing portion 31A and the second base end portion 321A of the second curved wing portion 32A are connected to the hub 2A at different positions in the radial direction Dr, the influence of vortices Sa generated on the upstream side in the fluid flow direction can be effectively suppressed from extending to vortices Sb generated on the downstream side in the flow direction.

[0023] Furthermore, in the above embodiment, a first wing support portion 23A is provided at the end portion 2a of the first side Da1 in the axial direction Da of the hub 2A, having a first diameter dimension D1 that is larger than the second diameter dimension D2 of the second wing support portion 24A. This makes it easier to firmly attach the hub 2A to an external mounting object.

[0024] Furthermore, in the above embodiment, by providing the hub 2A with a reduced diameter portion 22 in which the diameter gradually decreases from the first side Da1 to the second side Da2 in the axial direction Da, a first wing support portion 23A having a first diameter D1 and a second wing support portion 24A having a second diameter D2 smaller than the first diameter D1 can be easily formed. Therefore, a configuration in which the first base end portion 311A ​​of the first curved wing portion 31A and the second base end portion 321A of the second curved wing portion 32A are positioned at different locations in the radial direction Dr can be easily realized. In addition, by providing the hub 2A with a reduced diameter portion 22, pressure loss around the hub 2A can be suppressed compared to forming a stepped shape portion on the hub 2A.

[0025] (Modification of the First Embodiment) In the above embodiment, the reduced diameter portion 22 is formed over the entire axial direction Da of the hub 2A, but the embodiment is not limited to this. The reduced diameter portion 22 on which the first wing support portion 23A and the second wing support portion 24A are provided may be formed only on a part of the axial direction Da of the hub 2A.

[0026] (Other Modifications of the First Embodiment) Figure 4 is a diagram showing the configuration of a toroidal propeller according to another modification of the first embodiment of the present disclosure. As shown in Figure 4, the toroidal propeller 1B according to this modification has a hub 2A and blades 3B. The blades 3B have a first blade intersection angle θ1 at the first base end 311B of the first curved blade section 31B, while the second blade intersection angle θ2 at the second base end 321B of the second curved blade section 32B is smaller. Here, the first blade intersection angle θ1 is the inclination angle of the line connecting the first leading edge 311f located on one side of the circumferential direction Dc of the blade 3B and the first trailing edge 311r located on the other side of the circumferential direction Dc at the first base end 311B, with respect to a virtual reference plane F that intersects the central axis O. The second wing crossing angle θ2 is the inclination angle with respect to the virtual reference plane F of the line connecting the second leading edge portion 321f, located on one side of the circumferential direction Dc at the second base end portion 321B, and the second trailing edge portion 321r, located on the other side of the circumferential direction Dc.

[0027] By making the second wing crossing angle θ2 of the second base end 321B smaller than the first wing crossing angle θ1 of the first base end 311B, the vortices generated around the second base end 321B can be made weaker than the vortices generated around the first base end 311B. Therefore, the generation of vortices around the hub 2B can be suppressed.

[0028] <Second Embodiment> Next, a second embodiment of the toroidal propeller according to the present disclosure will be described. In the second embodiment described below, the same reference numerals will be used for the same parts as in the first embodiment, and redundant explanations will be omitted. (Configuration of the toroidal propeller) Figure 5 is a diagram showing the configuration of a toroidal propeller according to the second embodiment of the present disclosure. As shown in Figure 5, the toroidal propeller 1C comprises a hub 2C and blades 3C. In Figure 5, only one blade 3C provided on the hub 2C is shown, but the toroidal propeller 1C has multiple blades 3C.

[0029] The hub 2C extends in the axial direction Da along the central axis O. In this embodiment, the hub 2C is formed in a cylindrical shape with a constant diameter in the radial direction Dr, from the end 2a of the first side Da1 in the axial direction Da to the end 2b of the second side Da2 in the axial direction Da.

[0030] The wing 3C is positioned radially outward from the hub 2C in the direction Dr. The wing 3C is formed in a loop shape. Specifically, each wing 3C integrally comprises a first curved wing section 31C, a second curved wing section 32C, and a wingtip 33C.

[0031] The first curved wing portion 31C has a first base portion 311C located on the inside in the radial direction Dr and a first tip portion 312C located on the outside in the radial direction Dr.

[0032] The first base end 311C is connected to the outer circumferential surface of the hub 2C. The first curved wing portion 31C curves outward from the first base end 311C toward the first tip end 312C in the radial direction Dr. The first intermediate portion 313C between the first base end 311C and the first tip end 312C is curved to protrude from the first base end 311C and the first tip end 312C in at least one of the axial direction Da and the circumferential direction Dc.

[0033] The second curved wing portion 32C is provided at least one of the axial direction Da and the circumferential direction Dc relative to the first curved wing portion 31C. The second curved wing portion 32C has a second base portion 321C located inside the radial direction Dr and a second tip portion 322C located outside the radial direction Dr.

[0034] The second curved wing portion 32C curves outward from the second base portion 321C toward the second tip portion 322C in the radial direction Dr. The second intermediate portion 323C between the second base portion 321C and the second tip portion 322C is curved to protrude from the second base portion 321C and the second tip portion 322C in at least one of the axial direction Da and the circumferential direction Dc. The second intermediate portion 323C of the second curved wing portion 32C is curved away from the first intermediate portion 313C of the first curved wing portion 31C in at least one of the axial direction Da and the circumferential direction Dc.

[0035] The second base end 321C is located at a different position from the first base end 311C. In this embodiment, the second base end 321C is joined to the first curved wing portion 31C at an intermediate position between the first base end 311C and the first tip portion 312C. As a result, the second base end 321C is located at a different position in the radial direction Dr from the first base end 311C. The radial distance K between the second base end 321C and the first base end 311C is preferably about 1.5 to 2.5 times the wing thickness of the first base end 311C.

[0036] The wingtip 33C is located at the outermost point in the radial direction Dr of the wing 3C. The wingtip 33C connects the first tip 312C of the first curved wing section 31C and the second tip 322C of the second curved wing section 32C.

[0037] (Effects) In the toroidal propeller 1C of the second embodiment described above, the first base end 311C of the first curved blade section 31C and the second base end 321C of the second curved blade section 32C, which constitute the loop-shaped blade 3C, are positioned at different locations in the radial direction Dr. Therefore, when the toroidal propeller 1C is rotated around the central axis O, the vortex generated around the first base end 311C of the first curved blade section 31C and the vortex generated around the second base end 321C of the second curved blade section 32C are at different locations in the radial direction Dr. Consequently, the superposition of the vortex generated around the first base end 311C of the first curved blade section 31C and the vortex generated around the second base end 321C of the second curved blade section 32C, which increases the effect of vortices, is suppressed. Therefore, when the toroidal propeller 1C rotates, the effect of vortices generated around the hub 2C is suppressed, improving efficiency and reducing noise. As a result, further improvements in propeller performance can be achieved.

[0038] Furthermore, in the second embodiment described above, the second base end 321C of the second curved wing portion 32C is connected to the first curved wing portion 31C at an intermediate position between the first base end 311C and the first tip end 312C. This makes it possible to achieve a configuration in which the first base end 311C of the first curved wing portion 31C and the second base end 321C of the second curved wing portion 32C are positioned at different locations in the radial direction Dr.

[0039] <Third Embodiment> Next, a third embodiment of the toroidal propeller according to the present disclosure will be described. In the third embodiment described below, only the configuration of the blades differs from the first embodiment, so the same reference numerals are used for the same parts as in the first embodiment, and redundant explanations will be omitted. (Configuration of the toroidal propeller) Figure 6 is a diagram showing the configuration of a toroidal propeller according to the third embodiment of the present disclosure. As shown in Figure 6, the toroidal propeller 1D comprises a hub 2D and blades 3D. In Figure 6, only one blade 3D provided on the hub 2D is shown, but the toroidal propeller 1D has multiple blades 3D.

[0040] The hub 2D extends in the axial direction Da along the central axis O. The hub 2A of the present embodiment is formed in a frustum shape with a gradually decreasing diameter dimension in the radial direction Dr intersecting the axial direction Da, from the end 2a on the first side Da1 of the axial direction Da to the end 2b on the second side Da2 of the axial direction Da. Note that the hub 2D may be in a cylindrical shape with a constant diameter dimension in the radial direction Dr from the end 2a on the first side Da1 of the axial direction Da to the end 2b on the second side Da2 of the axial direction Da.

[0041] The blade 3D is provided outside the hub 2D in the radial direction Dr. The blade 3D is formed in a loop shape. Specifically, each blade 3D integrally includes a first curved blade portion 31D, a second curved blade portion 32D, and a blade end portion 33D.

[0042] The first curved blade portion 31D has a first base end portion 311D located inside the radial direction Dr and a first tip end portion 312D located outside the radial direction Dr.

[0043] The first base end portion 311D is connected to the outer peripheral surface of the hub 2D. The first curved blade portion 31D curves and extends from the first base end portion 311D toward the first tip end portion 312D outside the radial direction Dr. The first curved blade portion 31D of the present embodiment has a first forward curved portion 314D and a first rearward curved portion 315D.

[0044] The first forward curved portion 314D curves at least on one side in the circumferential direction Dc of the blade 3D and / or on the first side Da1 of the axial direction Da. The first rearward curved portion 315D is provided outside the first forward curved portion 314D in the radial direction Dr. The first rearward curved portion 315D curves at least on the other side in the circumferential direction Dc and / or on the second side Da2 of the axial direction Da.

[0045] The second curved blade portion 32D is provided at a distance from the first curved blade portion 31D in at least one of the axial direction Da and the circumferential direction Dc. The second curved blade portion 32D has a second base end portion 321D located inside the radial direction Dr and a second tip end portion 322D located outside the radial direction Dr. The second curved blade portion 32D curves and extends from the second base end portion 321D toward the second tip end portion 322D outside the radial direction Dr.

[0046] The second curved wing portion 32D has a second rear curved portion 324D and a second front curved portion 325D. The second rear curved portion 324D is curved so as to be separated from at least one of the other side in the circumferential direction Dc with respect to the first front curved portion 314D and the second side Da2 in the axial direction Da. The second front curved portion 325D is provided on the outer side in the radial direction Dr with respect to the second rear curved portion 324D. The second front curved portion 325D is curved so as to be separated from at least one of one side in the circumferential direction Dc with respect to the first rear curved portion 315D and the first side Da1 in the axial direction Da.

[0047] The first base end portion 311A connected to the first wing support portion 23A and the second base end portion 321A connected to the second wing support portion 24A are connected to the hub 2D at different positions in the axial direction Da and the radial direction Dr.

[0048] The wing end portion 33D is provided at the outermost side in the radial direction Dr in the wing 3D. The wing end portion 33D connects the first tip end portion 312D of the first curved wing portion 31D and the second tip end portion 322D of the second curved wing portion 32D.

[0049] (Function and effect) In the toroidal propeller 1D of the above embodiment, the first base end portion 311D of the first curved wing portion 31D and the second base end portion 321D of the second curved wing portion 32D that constitute the loop-shaped wing 3D are arranged at different positions in the radial direction Dr. For this reason, when the toroidal propeller 1D is rotated around the central axis O, the vortices generated around the first base end portion 311D of the first curved wing portion 31D and the vortices generated around the second base end portion 321D of the second curved wing portion 32D are different in position in the radial direction Dr. Therefore, it is possible to suppress the superposition of the vortices generated around the first base end portion 311D of the first curved wing portion 31D and the vortices generated around the second base end portion 321D of the second curved wing portion 32D and the increase in the influence of the vortices. Therefore, when the toroidal propeller 1D rotates, the influence of the vortices generated around the hub 2D can be suppressed, and the efficiency can be improved and the noise can be reduced. As a result, the propeller performance can be further improved.

[0050] Furthermore, in the above embodiment, the first forward curved portion 314D and the first rearward curved portion 315D of the first curved blade 31D, and the second rearward curved portion 324D and the second forward curved portion 325D of the second curved blade 32D, are in opposite directions. As a result, pressure fluctuations on the blade surface can be canceled out in the first curved blade 31D and the second curved blade 32D, contributing to noise reduction. In addition, vortices (hub vortices) generated around the first base end portion 311D and the second base end portion 321D can be reduced.

[0051] <Fourth Embodiment> Next, a fourth embodiment of the toroidal propeller according to the present disclosure will be described. In the fourth embodiment described below, only the configuration of the blades differs from that of the first embodiment, so the same reference numerals are used for the same parts as in the first embodiment and redundant explanations will be omitted. (Configuration of the toroidal propeller) Figure 7 is a diagram showing the configuration of a toroidal propeller according to the fourth embodiment of the present disclosure. As shown in Figure 7, the toroidal propeller 1E comprises a hub 2E and a plurality of blades 3E.

[0052] The hub 2E extends in the axial direction Da along the central axis O. Note that in Figure 7, the axial direction Da is a direction that intersects the plane of the paper and is therefore not shown. In this embodiment, the hub 2E is formed in a frustoconical shape in which the diameter in the radial direction Dr intersecting the axial direction Da gradually decreases from the end 2a of the first side Da1 in the axial direction Da to the end 2b of the second side Da2 in the axial direction Da. Alternatively, the hub 2E may be cylindrical in which the diameter in the radial direction Dr is constant from the end 2a of the first side Da1 in the axial direction Da to the end 2b of the second side Da2 in the axial direction Da.

[0053] Multiple blades 3E are provided on the outside of the hub 2E in the radial direction Dr, which intersects the axial direction Da. Multiple blades 3E are provided at intervals in the circumferential direction Dc around the central axis O. In this embodiment, for example, three sets of blades 3E are provided. The number of blades 3E may be two sets, or four or more sets may be provided.

[0054] Each of the multiple wings 3E is formed in a loop shape. Specifically, each wing 3E integrally comprises a first curved wing section 31E, a second curved wing section 32E, and a wingtip 33E.

[0055] The first curved wing portion 31E has a first base portion 311E located on the inside in the radial direction Dr and a first tip portion 312E located on the outside in the radial direction Dr.

[0056] The first base end 311E is connected to the outer circumferential surface of the hub 2E. The first curved wing portion 31E curves outward from the first base end 311E toward the first tip end 312E in the radial direction Dr. In this embodiment, the first intermediate portion 313E between the first curved wing portion 31E and the first tip end 312E is curved toward the rear side Ddr of the rotation direction Dd of the wing 3E around the central axis O, relative to the first base end 311E and the first tip end 312E.

[0057] The second curved wing portion 32E is provided at a distance from the first curved wing portion 31E in the circumferential direction Dc and the axial direction Da. The second curved wing portion 32E has a second base portion 321E located on the inside in the radial direction Dr and a second tip portion 322E located on the outside in the radial direction Dr.

[0058] The second base end 321E is located at a different position from the first base end 311E. In this embodiment, the second base end 321E is located at different positions relative to the first base end 311E in the axial direction Da, radial direction Dr, and circumferential direction Dc. The second base end 321E is connected to the outer circumferential surface of the hub 2E. The second curved wing portion 32E curves outward from the second base end 321E toward the second tip portion 322E in the radial direction Dr. In this embodiment, the second intermediate portion 323E between the second curved wing portion 32E and the second tip portion 322E is curved toward the rear side Ddr of the rotation direction Dd of the wing 3E around the central axis O relative to the second base end 321E and the second tip portion 322E.

[0059] The wingtip 33E is located at the outermost point in the radial direction Dr of the wing 3E. The wingtip 33E connects the first tip 312E of the first curved wing section 31E and the second tip 322E of the second curved wing section 32E.

[0060] (Effects) In the toroidal propeller 1E of the fourth embodiment described above, the first base end 311E of the first curved blade section 31E and the second base end 321E of the second curved blade section 32E, which constitute the loop-shaped blade 3E, are positioned at different locations in the radial direction Dr. Therefore, when the toroidal propeller 1E is rotated around the central axis O, the vortex generated around the first base end 311E of the first curved blade section 31E and the vortex generated around the second base end 321E of the second curved blade section 32E are at different locations in the radial direction Dr. Consequently, the superposition of the vortex generated around the first base end 311E of the first curved blade section 31E and the vortex generated around the second base end 321E of the second curved blade section 32E, which increases the effect of vortices, is suppressed. Therefore, when the toroidal propeller 1E rotates, the effect of vortices generated around the hub 2E is suppressed, improving efficiency and reducing noise. As a result, further improvements in propeller performance can be achieved.

[0061] Furthermore, in the fourth embodiment described above, the first intermediate portion 313E of the first curved blade section 31E and the second intermediate portion 323E of the second curved blade section 32E are curved to the rear side Ddr in the rotation direction Dd of the blade 3E. As a result, the blade 3E has a so-called forward skew, where the first tip portion 312E of the first curved blade section 31E and the second tip portion 322E of the second curved blade section 32E protrude to the front side Ddf in the rotation direction Dd of the blade 3E. With such a toroidal propeller 1E, vibrations caused by vortices are suppressed while fluid force fluctuations are suppressed. Moreover, since the first tip portion 312E and the second tip portion 322E are connected by the blade tip 33E, the rigidity of the portion of the blade 3E that protrudes to the front side Ddf in the rotation direction Dd can be increased, and the generation of vibrations can be suppressed more effectively. As a result, the propeller performance can be further improved.

[0062] (Other Embodiments) Although embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes design changes and the like that do not depart from the gist of the present disclosure. In the above embodiments, examples were shown in which the hubs 2A to 2E are frustoconical in shape, with the diameter gradually decreasing from the end 2a of the first side Da1 in the axial direction Da to the end 2b of the second side Da2 in the axial direction Da, but the present invention is not limited to this. The hubs 2A to 2E (reduced diameter portion 22) may also be configured such that the diameter gradually decreases from the end 2b of the second side Da2 in the axial direction Da to the end 2a of the first side Da1 in the axial direction Da. Furthermore, the hubs 2A to 2E may have a stepped shape, having a first wing support portion 23A having a first diameter D1 and a second wing support portion 24A formed at a different position in the axial direction Da from the first wing support portion 23A and having a second diameter D2. Furthermore, the cross-sectional shape of the hubs 2A to 2E, as viewed from the axial direction Da, may be other than circular, for example, a polygonal shape.

[0063] <Note> The toroidal propellers 1A to 1E described in each embodiment can be understood, for example, as follows.

[0064] (1) The toroidal propellers 1A to 1E according to the first embodiment are toroidal propellers 1A to 1E that are rotationally driven around a central axis O, and include hubs 2A, 2C to 2E extending in an axial direction Da along the central axis O, and loop-shaped blades 3A to 3E provided on the outside of the radial direction Dr that intersects the axial direction Da with respect to the hubs 2A, 2C to 2E, wherein the blades 3A to 3E include first curved blade portions 31A to 31E that curve outward from first base ends 311A ​​to 311E located on the inside of the radial direction Dr, and second base ends 321A to 32 provided on the inside of the radial direction Dr at a position different from the first base ends 311A ​​to 311E The first curved wing portion 32A, 32C-32E extends outward from 1E in the radial direction Dr and is provided at least one of the axial direction Da and the circumferential direction Dc around the central axis O relative to the first curved wing portion 31A-31E, and the wing end portion 33A-33E is provided integrally at the outermost part in the radial direction Dr, connecting the first tip portion 312A-312E of the first curved wing portion 31A-31E on the radial direction Dr side and the second tip portion 322A-322E of the second curved wing portion 32A-32E on the radial direction Dr side, wherein the first base portion 311A-311E and the second base portion 321A-321E are positioned at different locations in the radial direction Dr.

[0065] As a result, when the toroidal propellers 1A to 1E are rotated around the central axis O, the vortices (hub vortices) generated around the first base ends 311A ​​to 311E of the first curved blade sections 31A to 31E and the vortices (hub vortices) generated around the second base ends 321A to 321E of the second curved blade sections 32A to 32E are located at different positions in the radial direction Dr. Therefore, the superposition of the vortices generated around the first base ends 311A ​​to 311E of the first curved blade sections 31A to 31E and the vortices generated around the second base ends 321A to 321E of the second curved blade sections 32A to 32E, which would increase the influence of the vortices, is suppressed. Consequently, when the toroidal propellers 1A to 1E are rotated, the influence of the vortices generated around the hubs 2A, 2C to 2E is suppressed, improving efficiency and reducing noise. As a result, further improvements in propeller performance can be achieved.

[0066] (2) The toroidal propeller 1A according to the second embodiment is the toroidal propeller 1A of (1), wherein the hub 2A has a first diameter dimension D1 and a first wing support portion 23A to which the first base end portion 311A ​​is connected, and a second wing support portion 24A formed on the second side Da2 in the axial direction Da with respect to the first wing support portion 23A and having a second diameter dimension D2 smaller than the first diameter dimension D1 and to which the second base end portion 321A is connected.

[0067] As a result, the hub 2A has a first wing support portion 23A having a first diameter dimension D1 to which the first base end portion 311A ​​is connected, and a second wing support portion 24A having a second diameter dimension D2 smaller than the first diameter dimension D1 to which the second base end portion 321A is connected. Therefore, the first base end portion 311A ​​of the first curved wing portion 31A and the second base end portion 321A of the second curved wing portion 32A can be connected to the hub 2A at different positions in the radial direction Dr. Furthermore, since the second wing support portion 24A is formed on the second side Da2 in the axial direction Da relative to the first wing support portion 23A, when the fluid flows in the axial direction Da due to the rotation of the toroidal propeller 1A, the vortices generated on the upstream side in the direction of fluid flow, among the vortices generated around the first base end portion 311A ​​of the first curved wing portion 31A and the vortices generated around the second base end portion 321A of the second curved wing portion 32A, are more likely to affect the vortices generated on the downstream side in the direction of flow. However, since the first base end 311A ​​of the first curved blade 31A and the second base end 321A of the second curved blade 32A are connected to the hub 2A at different positions in the radial direction Dr, the influence of vortices generated upstream in the fluid flow direction on vortices generated downstream in the flow direction can be effectively suppressed.

[0068] (3) The toroidal propeller 1A according to the third embodiment is the toroidal propeller 1A of (2), wherein the hub 2A has an end 2a on the first side Da1 in the axial direction Da that can be connected to an external mounting target 100.

[0069] In this way, a first wing support portion 23A is provided at the end portion 2a of the first side Da1 in the axial direction Da of the hub 2A, having a first diameter dimension D1 that is larger than the second diameter dimension D2 of the second wing support portion 24A. This makes it easier to firmly attach the hub 2A to the external mounting target 100.

[0070] (4) The toroidal propeller 1A according to the fourth embodiment is the toroidal propeller 1A of (2) or (3), wherein the hub 2A has a reduced diameter portion 22 in at least a part of the axial direction Da, the diameter of which gradually decreases from the first side Da1 to the second side Da2 of the axial direction Da, and the first wing support portion 23A and the second wing support portion 24A are formed in the reduced diameter portion 22.

[0071] By providing the hub 2A with a reduced diameter section 22 in which the diameter gradually decreases from the first side Da1 to the second side Da2 in the axial direction Da, it is possible to easily form a first wing support section 23A having a first diameter D1 and a second wing support section 24A having a second diameter D2 smaller than the first diameter D1. Therefore, it is possible to easily realize a configuration in which the first base end 311A ​​of the first curved wing section 31A and the second base end 321A of the second curved wing section 32A are positioned at different locations in the radial direction Dr. Furthermore, by providing the reduced diameter section 22 in the hub 2A, pressure loss around the hub 2A can be suppressed compared to forming a stepped shape on the hub 2A.

[0072] (5) The toroidal propeller 1B according to the fifth embodiment is any one of the toroidal propellers 1B from (1) to (4), wherein at the first base end 311B, the second wing crossing angle θ2 is smaller than the first wing crossing angle θ1, which is the angle of inclination of the line connecting the second leading edge 321f, which is located on one side Dc1 of the circumferential direction Dc of the wing 3B around the central axis O, and the first trailing edge 311r, which is located on the other side of the circumferential direction Dc, with respect to the virtual reference plane F intersecting the central axis O.

[0073] By making the second wing crossing angle θ2 of the second base end 321B smaller than the first wing crossing angle θ1 of the first base end 311B, the vortices generated around the second base end 321B can be made weaker than the vortices generated around the first base end 311B. Therefore, the generation of vortices around the hub 2B can be suppressed.

[0074] (6) The toroidal propeller 1C according to the sixth embodiment is the toroidal propeller 1C of (1), wherein the second base end 321C is joined to the first curved blade portion 31C in the intermediate portion between the first base end 311C and the first tip portion 312C.

[0075] By connecting the second base end 321C of the second curved wing portion 32C to the first curved wing portion 31C in the intermediate portion between the first base end 311C and the first tip end 312C, a configuration can be achieved in which the first base end 311C of the first curved wing portion 31C and the second base end 321C of the second curved wing portion 32C are positioned at different locations in the radial direction Dr.

[0076] (7) The toroidal propeller 1D according to the seventh embodiment is any one of the toroidal propellers 1D of (1) to (5), wherein the first curved blade portion 31D has a first forward curved portion 314D that curves toward one side Dc1 of the circumferential direction Dc of the blade 3D about the central axis O, and a first rearward curved portion 315D provided on the inside or outside of the radial direction Dr relative to the first forward curved portion 314D and curving toward the other side of the circumferential direction Dc, and the second curved blade portion 32D has a second rearward curved portion 324D that curves toward the other side of the circumferential direction Dc so as to be separated from the first forward curved portion 314D toward the other side of the circumferential direction Dc, and a second forward curved portion 325D that curves toward one side Dc1 of the circumferential direction Dc so as to be separated from the first rearward curved portion 315D toward one side Dc1 of the circumferential direction Dc.

[0077] As a result, the curvature directions are opposite in the first forward curved section 314D and the first rearward curved section 315D of the first curved wing section 31D, and in the second rearward curved section 324D and the second forward curved section 325D of the second curved wing section 32D. Therefore, pressure fluctuations on the wing surface can be canceled out in the first curved wing section 31D and the second curved wing section 32D, contributing to noise reduction. In addition, since the load received by the first base end 311D and the second base end 321D is distributed, vortices (hub vortices) generated around the first base end 311D and the second base end 321D can be reduced.

[0078] (8) The toroidal propeller 1E according to the eighth embodiment is the toroidal propeller 1E of (1), wherein the first curved blade portion 31E has a first intermediate portion 313E between the first base portion 311E and the first tip portion 312E that is curved to the rear side Ddr of the rotation direction Dd of the blade 3E around the central axis O, relative to the first base portion 311E and the first tip portion 312E, and the second curved blade portion 32E has a second intermediate portion 323E between the second base portion 321E and the second tip portion 322E that is curved to the rear side Ddr of the rotation direction Dd of the blade 3E around the central axis O.

[0079] As a result, the wing 3E has a so-called forward skew, where the first tip 312E of the first curved wing section 31E and the second tip 322E of the second curved wing section 32E protrude to the rear side Ddr in the rotational direction Dd of the wing 3E, thereby suppressing vibrations caused by vortices while suppressing fluid force fluctuations. Furthermore, since the first tip 312E and the second tip 322E are connected by the wingtip 33E, the rigidity of the portion of the wing 3E that protrudes to the forward side Ddf in the rotational direction Dd can be increased, and the generation of vibrations can be suppressed more effectively.

[0080] (9) A toroidal propeller 1D according to the ninth embodiment is a toroidal propeller 1D that is rotationally driven about a central axis O, comprising a hub 2D extending in an axial direction Da along the central axis O, and a loop-shaped blade 3D provided on the outside of the hub 2D in a radial direction Dr that intersects the axial direction Da, wherein the blade 3D comprises a first curved blade portion 31D that curves outward from a first base end 311D located on the inside of the radial direction Dr, a second curved blade portion 32D that curves outward from a second base end 321D located on the inside of the radial direction Dr at a different position from the first base end 311D, and is provided at least one of the axial direction Da and the circumferential direction Dc about the central axis O apart from the first curved blade portion 31D, and the outermost part of the radial direction Dr, the first curved blade portion 31 The first curved wing portion 31D comprises a first tip portion 312D on the radially outer side of D and a second base portion 321D on the radially outer side of the second curved wing portion 32D, with the first curved wing portion 31D comprising a first forward curved portion 314D that curves toward one side Dc1 in the circumferential direction Dc of the wing 3D around the central axis O, and provided on the inside or outside of the radial direction Dr relative to the first forward curved portion 314D, in the circumferential direction Dc The second curved wing portion 32D has a first rearward curved portion 315D that curves toward the other side of the first forward curved portion 314D, and the second curved wing portion 324D has a second rearward curved portion 324D that curves toward the other side of the circumferential direction Dc so as to be separated from the first forward curved portion 314D toward the other side of the circumferential direction Dc, and a second forward curved portion 325D that curves toward one side Dc1 of the circumferential direction Dc so as to be separated from the first rearward curved portion 315D toward one side Dc1 of the circumferential direction Dc.

[0081] As a result, the curvature directions are opposite in the first forward curved section 314D and the first rearward curved section 315D of the first curved wing section 31D, and in the second rearward curved section 324D and the second forward curved section 325D of the second curved wing section 32D. Therefore, pressure fluctuations on the wing surface can be canceled out in the first curved wing section 31D and the second curved wing section 32D, contributing to noise reduction. In addition, since the load received by the first base end 311D and the second base end 321D is distributed, vortices (hub vortices) generated around the first base end 311D and the second base end 321D can be reduced. As a result, further improvements in propeller performance can be achieved.

[0082] (10) A toroidal propeller 1E according to the tenth embodiment is a toroidal propeller 1E that is rotationally driven about a central axis O, comprising a hub 2E extending in an axial direction Da along the central axis O, and a loop-shaped blade 3E provided on the outside of the hub 2E in a radial direction Dr that intersects the axial direction Da, wherein the blade 3E comprises a first curved blade portion 31E that curves outward from a first base end 311E located on the inside of the radial direction Dr, and a second curved blade portion 32 that curves outward from a second base end 321E located on the inside of the radial direction Dr at a different position from the first base end 311E, and is provided at least one of the axial direction Da and the circumferential direction Dc about the central axis O relative to the first curved blade portion 31E The first curved wing portion 31E comprises E and a wingtip 33E that is located at the outermost point in the radial direction Dr and connects the first tip 312E of the first curved wing portion 31E on the radial direction Dr side and the second tip 322E of the second curved wing portion 32E on the radial direction Dr side. The first curved wing portion 31E has a first intermediate portion 313E between the first base end 311E and the first tip 312E that is curved to the rear side Ddr of the rotation direction Dd of the wing 3E around the central axis O, relative to the first base end 311E and the first tip 312E. The second curved wing portion 32E has a second intermediate portion 323E between the second base end 321E and the second tip 322E that is curved to the rear side Ddr of the rotation direction Dd of the wing 3E around the central axis O.

[0083] As a result, the wing 3E has a so-called forward skew, where the first tip 312E of the first curved wing section 31E and the second tip 322E of the second curved wing section 32E protrude to the rear side Ddr in the rotation direction Dd of the wing 3E. This suppresses vibrations caused by vortices while suppressing fluid force fluctuations. Furthermore, since the first tip 312E and the second tip 322E are connected by the wingtip 33E, the rigidity of the portion of the wing 3E that protrudes to the forward side Ddf in the rotation direction Dd can be increased, and the generation of vibrations can be suppressed more effectively. As a result, propeller performance can be further improved.

[0084] The toroidal propeller of this disclosure makes it possible to further improve propeller performance.

[0085] 1A to 1E Toroidal propeller 2A to 2E Hub 2a, 2b End part 3A to 3E Wing 22 Reduced diameter part 23A First wing support part 24A Second wing support part 31A to 31E First curved wing part 32A to 32E Second curved wing part 33A to 33E Wing tip part 100 Installation target 311A ​​to 311E First base end portion 311f First front edge portion 311r First rear edge portion 312A to 312E First tip portion 313A, 313C, 313E First intermediate portion 314D First front curved portion 315D First rear curved portion 321A to 321E Second base end portion 321f Second front edge portion 321r Second rear edge portion 322A to 322E Second tip 323A, 323C, 323E Second intermediate section 324D Second rear curved section 325D Second front curved section F Virtual reference plane

Claims

1. A toroidal propeller that is rotationally driven around a central axis, comprising: a hub extending axially along the central axis; and a loop-shaped blade provided radially outward and intersecting the axial direction with respect to the hub, wherein the blade comprises: a first curved blade portion extending inward from a first base end located radially inward; a second curved blade portion extending radially outward from a second base end located radially inward at a different position from the first base end, and provided at least one of the axial direction and the circumferential direction around the central axis relative to the first curved blade portion; and a blade end at the outermost radial point connecting the radially outward first tip of the first curved blade portion and the radially outward second tip of the second curved blade portion, wherein the first base end and the second base end are located at different radial positions.

2. The toroidal propeller according to claim 1, wherein the hub has a first diameter dimension and a first wing support portion to which the first base end is connected, and a second wing support portion formed on the second axial side of the first wing support portion and having a second diameter dimension smaller than the first diameter dimension and to which the second base end is connected.

3. The toroidal propeller according to claim 2, wherein the first axial end of the hub is connectable to an external mounting object.

4. The toroidal propeller according to claim 2 or 3, wherein the hub has a reduced-diameter portion in at least a part of the axial direction, the diameter of which gradually decreases from the first side to the second side in the axial direction, and the first wing support portion and the second wing support portion are formed in the reduced-diameter portion.

5. A toroidal propeller according to claim 1 or 2, wherein, at the first base end, the second wing crossing angle is smaller than the first wing crossing angle, which is the angle of inclination of the line connecting the second leading edge located on one side of the circumferential direction of the wing and the first trailing edge located on the other side of the circumferential direction of the wing, with respect to a virtual reference plane intersecting the central axis, with respect to the virtual reference plane, at the second base end.

6. The toroidal propeller according to claim 1, wherein the second base end is joined to the first curved wing portion at an intermediate position between the first base end and the first tip end.

7. The toroidal propeller according to claim 1 or 2, wherein the first curved wing portion has a first forward curved portion that curves to one side in the circumferential direction of the wing about the central axis, and a first rearward curved portion provided radially inward or outward of the first forward curved portion and curving to the other side in the circumferential direction, and the second curved wing portion has a second rearward curved portion that curves to the other side in the circumferential direction so as to move away from the first forward curved portion to the other side in the circumferential direction, and a second forward curved portion that curves to one side in the circumferential direction so as to move away from the first rearward curved portion to one side in the circumferential direction.

8. The toroidal propeller according to claim 1 or 2, wherein the first curved wing portion is curved in the other direction in the circumferential direction of the wing around the central axis, with respect to the first base end and the first tip end, and the second curved wing portion is curved in the other direction in the circumferential direction of the wing around the central axis, with respect to the second base end and the second tip end, and the second intermediate wing portion is curved in the other direction in the circumferential direction of the wing around the central axis.

9. A toroidal propeller that is rotationally driven around a central axis, comprising: a hub extending axially along the central axis; and a loop-shaped blade provided radially outward and intersecting the axial direction with respect to the hub, wherein the blade comprises: a first curved blade portion extending radially outward from a first base end located radially inward; a second curved blade portion extending radially outward from a second base end located radially inward at a different position from the first base end, and provided at least one of the axial direction and the circumferential direction around the central axis relative to the first curved blade portion; and a blade end at the outermost radial point connecting the radially outward first tip of the first curved blade portion and the radially outward second tip of the second curved blade portion, wherein the first curved blade portion comprises: a first forward curved portion curving toward one side in the circumferential direction of the blade around the central axis, A toroidal propeller having a first rearward curved portion provided radially inward or outward from the first forward curved portion and curving toward the other side in the circumferential direction, the second curved wing portion having a second rearward curved portion that curves toward the other side in the circumferential direction so as to move away from the first forward curved portion toward the other side in the circumferential direction, and a second forward curved portion that curves toward one side in the circumferential direction so as to move away from the first rearward curved portion toward one side in the circumferential direction.

10. A toroidal propeller that is rotationally driven around a central axis, comprising: a hub extending axially along the central axis; and a loop-shaped blade provided radially outward and intersecting the axial direction with respect to the hub, wherein the blade comprises: a first curved blade portion extending inward from a first base end located radially inward; a second curved blade portion extending radially outward from a second base end located radially inward at a different position from the first base end, and provided at least one of the axial direction and the circumferential direction around the central axis relative to the first curved blade portion; and a blade end at the outermost radial point connecting the radially outward first tip of the first curved blade portion and the radially outward second tip of the second curved blade portion, wherein the first curved blade portion has a first intermediate blade portion between the first base end and the first tip that curves rearward in the rotational direction of the blade around the central axis, with respect to the first base end and the first tip. The second curved wing section is a toroidal propeller in which the second intermediate wing section between the second base end and the second tip end is curved rearward in the direction of rotation of the wing around the central axis, relative to the second base end and the second tip end.

Images