Propulsion device for applying thrust to fluid

Abstract

A propulsion device for applying thrust to a fluid is disclosed, the propulsion device comprising a central hub (10, 110, 210) and at least two propulsion devices (20, 120, 220). The central hub (10, 110, 210) has a front end (11) and a rear end (12) and is rotatable about a rotation axis (A) extending longitudinally between the front end (11) and the rear end (12); the at least two propulsion devices (20, 120, 220) protrude radially from the hub (10, 110, 210) and are evenly distributed around the circumference of the hub (10, 110, 210). Each propulsion device (20, 120, 220) comprises a front propulsion element (30) extending from a front inner end (31) to a front outer end (32). The rear propulsion element (40) extends from a rear inner end (41) to a rear outer end (42). The outer guide element (60) extends from the front outer end (32) to the rear outer end (42). The inner guide element (70) extends from the front inner end (31) to the rear inner end (41) at an inner guide element distance (IG). The elongated front spacing member (35) and the elongated rear spacing member (45) extend radially from the hub (10) to the inner guide element (60). At least one intermediate propulsion element (50) is arranged between the front propulsion element (30) and the rear propulsion element (40) and extends radially from the inner guide element (70) to the outer guide element (60). The inner guide element (70), the front spacing member (35), the rear spacing member (45) and the outer periphery of the hub (10) define an open space that allows fluid to pass freely.

Description

Technical Field

[0001] This disclosure generally relates to the field of propulsion devices for generating thrust to fluids. The propulsion devices disclosed herein can be used in a variety of applications, such as for the propulsion of vehicles including marine and aerial vehicles (including unmanned aerial vehicles), and for the generation of forced fluid flow, such as fans, blowers, and liquid pumps. Background Technology

[0002] Traditional propellers typically consist of a rotating hub and two or more blades, which are fixed to the hub and project radially from it. The blades are arranged at intervals, thus defining a helical structure resembling a spiral.

[0003] Traditional propellers typically exhibit high rotational drag, resulting in high motor loads and low energy efficiency. They are also susceptible to cavitation, which can damage the blades, cause undesirable vibrations, and generate noise. Furthermore, these traditional propellers often exhibit significant slippage, further reducing energy efficiency.

[0004] GB188,206 discloses a propeller comprising a hub and a plurality of radially supported main blades fixed to the hub. Each main blade is connected to a first auxiliary blade disposed in front of the main blade and a second auxiliary blade disposed behind the main blade. The tips of the main blades and auxiliary blades extend radially beyond the junction between the main blades and auxiliary blades. Summary of the Invention

[0005] The object of this invention is to provide an enhanced propulsion device for generating thrust into a fluid.

[0006] Another objective is to provide efficient propulsion equipment.

[0007] Another objective is to provide a propulsion device that generates an axial flow with relatively very small separation.

[0008] Another objective is to provide a propulsion device that exhibits relatively low resistance to fluids.

[0009] Another objective is to provide propulsion devices that prevent cavitation.

[0010] Another objective is to provide propulsion devices with relatively low slip ratios.

[0011] Generally, unless otherwise expressly defined herein, all terms used in the claims shall be interpreted according to their ordinary meaning in the art. Unless otherwise expressly stated, all references to “an element, device, component, apparatus, step, etc.” shall be openly interpreted as referring to at least one instance of an element, device, component, apparatus, step, etc. Unless expressly stated otherwise, the steps of any method disclosed herein need not be performed in the exact order disclosed.

[0012] According to a first aspect, this disclosure provides a propulsion device as described in appended claim 1. The propulsion device is arranged to apply thrust to a fluid. The propulsion device includes a central hub and at least two propulsion devices. The central hub has a front end and a rear end and is rotatable about a rotation axis extending longitudinally between the front end and the rear end. At least two propulsion devices project radially from the hub and are evenly distributed around the circumference of the hub. Each propulsion device includes a front propulsion element and a rear propulsion element, the front propulsion element extending radially from a front inner end to a front outer end, and the rear propulsion element extending radially from a rear inner end to a rear outer end. An outer guide element maintains a radial outer guide element distance from the rotation axis extending from the front outer end to the rear outer end, and an inner guide element maintains a radial inner guide element distance from the rotation axis extending from the front inner end to the rear inner end. An elongated front spacing member and an elongated rear spacing member extend radially from the hub to the inner guide element. At least one intermediate propulsion element is arranged between the front propulsion element and the rear propulsion element and extends radially from the inner guide element to the outer guide element. The longitudinal projections of the front propulsion element, the intermediate propulsion element, and the rear propulsion element at least partially overlap. The inner guide element, front spacing member, rear spacing member, and outer periphery of the hub define an open space that allows fluid to pass freely.

[0013] By incorporating an intermediate propulsion element (extending from an inner guide element radially positioned at a distance from the hub) within the propulsion device, an additional thrust-generating surface is provided on the outer periphery of the device. This thrust-generating region on the outer periphery provides greater thrust and lower axial and tangential drag than the blade region in the center of a conventional propeller. Therefore, the intermediate propulsion element improves the efficiency of the propulsion device by increasing thrust while maintaining low drag. In a propulsion unit, the inner and outer guide elements, extending longitudinally between all propulsion elements, reduce radial flow and promote axial flow. Consequently, the axial component of the flow generated by the propulsion device increases while maintaining low lateral flow separation. This also contributes to improved propulsion device efficiency. The outer and inner guide elements also increase the rigidity of the propulsion device, allowing for relatively thinner propulsion elements and reduced vibration. The outer guide element also reduces cavitation on the outer periphery of the propulsion elements, thereby reducing wear, noise, and other vibrations.

[0014] The propulsion device has proven to be highly efficient, low-drag, with highly concentrated axial flow and minimal lateral separation, low cavitation, and low levels of noise and other vibrations in both the axial and circumferential directions.

[0015] In this implementation of the propulsion device, the longitudinal projections of the front propulsion element, the intermediate propulsion element, and the rear propulsion element completely overlap. This further reduces axial drag.

[0016] The axial projection lengths of the chords of the forward, rear, and intermediate propulsion elements can be essentially constant. Therefore, the axial projections of the propulsion elements are rectangular or rhomboid. In this way, while keeping the chords short, the effective area of ​​the propulsion elements can be large. This, in turn, increases thrust while minimizing cavitation.

[0017] The maximum chord length of the front, rear, and intermediate propulsion elements can be a short chord length. This short chord length is defined by the NACA standard nomenclature. Therefore, the propulsion elements exhibit a relatively short circumferential extension in the effective region radially outside the inner guide element, which reduces cavitation.

[0018] The inner guide element distance (IG) can be at least 40% of the outer guide distance (OG). This means that the distance between the intermediate propulsion element and the axis of rotation is large enough to provide greater thrust relative to drag.

[0019] The outer guide element can protrude rearward from the rear outer end. The protruding part of the outer guide element provides what is called a wing, which effectively reduces cavitation.

[0020] The outer and inner guide elements can have a substantially constant longitudinal cross-section that protrudes outward. This reduces circumferential drag.

[0021] The outer and inner guide elements can have a substantially constant longitudinal cross-section with an inward concavity. This further reduces circumferential drag.

[0022] The convex or concave radius of curvature can be approximately equal to the radial distance from the axis of rotation to the corresponding outer and inner guide elements. This also reduces circumferential drag.

[0023] The distance between the leading and trailing edges of each of the forward, rearward, and intermediate propulsion elements can be essentially constant. This allows for a larger effective propulsion element area while maintaining a relatively short chord.

[0024] The front and rear spacing components can be aligned longitudinally.

[0025] The front and rear spacing members can be arranged to extend radially from the front inner end and the rear inner end to the hub, respectively.

[0026] Each propulsion device may include multiple intermediate propulsion elements, preferably two or three. This further enhances the advantage of arranging an effective propulsion element area on the outer periphery of the propulsion device.

[0027] Propulsion equipment may include:

[0028] Two propulsion devices spaced 180° apart in the circumferential direction; or

[0029] Three propulsion devices spaced 120° apart in the circumferential direction; or

[0030] Four propulsion devices spaced 90° apart in the circumferential direction; or

[0031] Five propulsion devices spaced 72° apart in the circumferential direction; or

[0032] Six propulsion devices spaced 60° apart in the circumferential direction.

[0033] Other objects and advantages of the propulsion device according to the first, second and third aspects will become apparent from the following description of exemplary embodiments and the appended claims. Attached Figure Description

[0034] The aspects and implementation methods will now be described by way of example and with reference to the accompanying drawings, wherein:

[0035] Figure 1 This is a perspective view of the propulsion device according to the first embodiment.

[0036] Figures 2a to 2c They are Figure 1 The side view, front view, and rear view of the propulsion device are shown.

[0037] Figure 3 This is a perspective view of the propulsion device according to the second embodiment.

[0038] Figure 4 This is a perspective view of the propulsion device according to the third embodiment. Detailed Implementation

[0039] The present disclosure will now be described more fully with reference to the accompanying drawings, in which certain embodiments of the invention are shown.

[0040] However, these aspects can be embodied in many different forms and should not be considered limiting; rather, these embodiments are provided by way of example to make this disclosure comprehensive and complete, and to fully convey the scope of all aspects of the invention to those skilled in the art. Throughout the description, the same numbers denote the same elements.

[0041] Figures 1 to 4 The propulsion devices shown are all intended for use in the propulsion of marine vehicles. Other embodiments not shown within the scope of this disclosure can be used for other applications, such as for the propulsion of aircraft including unmanned aerial vehicles or for generating forced fluid flow, such as fans, blowers, and pumps.

[0042] according to Figures 1 to 2c The marine propulsion device of the illustrated embodiment includes a central hub 10 rotatable about a central axis of rotation A. In the illustrated embodiment, the hub 10 is arranged to allow exhaust gases from an outboard or inboard engine (not shown) to pass through its interior. The hub has a tapered end, gradually tapering from a front end 11 to a rear end 12. The hub 10 has a central bore 13 extending longitudinally from the front end 11 to the rear end 12. A cylindrical internal spline sleeve 14 extends through the center of the bore 13. The sleeve 14 is secured to the inner wall of the bore 13 by four radial struts 15, forming an annular channel for exhaust gas discharge within the bore 13 surrounding the sleeve 14.

[0043] The propulsion device also includes two propulsion units 20, which are fixed to the outer peripheral surface of the hub 10 and spaced 180° apart. The two propulsion units are identical; for simplicity, only one will be described below.

[0044] Each propulsion device 20 includes a front propulsion element 30, a rear propulsion element 40, and an intermediate propulsion element 50. The front propulsion element 30 has a front inner end 31 and a front outer end 32. Correspondingly, the rear propulsion element 40 has a rear inner end 41 and a rear outer end 42.

[0045] The outer guide element 60 extends parallel to the rotation axis A, from the front outer end 32 to the rear outer end 42. The outer guide 60 is arranged at a radial distance OG from the rotation axis A. The outer guide element 60 protrudes axially a short distance behind the rear propulsion element 40, forming a rearwardly protruding wing 61.

[0046] The inner guide element 70 extends parallel to the axis of rotation A, from the front inner end 31 to the rear inner end 41. The inner guide element 70 is secured to the outer periphery of the hub by an elongated front spacing member 35 and an elongated rear spacing member 45. The spacing members 35 and 45 each extend radially from the hub to the inner guide element 70. In the illustrated embodiment, the front spacing member 35 forms a radially inward extension of the front propulsion element 30, and the rear spacing member forms a radially inward extension of the rear propulsion element 40. However, in other embodiments not shown, the spacing members may be arranged at other longitudinal locations on the inner guide element, provided that the spacing members hold the inner guide element 70 at a radial distance from the hub 10.

[0047] The inner guide element 70 is arranged at a radial distance IG from the rotation axis A. The distance IG is shorter than the outer guide distance OG, but greater than the maximum outer diameter of the hub 10. That is, the inner guide element 70 is radially arranged between the outer periphery of the hub and the outer guide element 60. In the illustrated embodiment, the distance IG is approximately 60% of the distance OG. Preferably, the distance IG is 40% to 75% of the distance OG.

[0048] The outer radial surface of the outer guide element 60 is convex, and its radius of curvature is approximately equal to the distance OG between the outer guide elements. The inner radial surface of the outer guide element 60 is concave, and its radius of curvature is also approximately equal to the distance OG between the outer guide elements.

[0049] Accordingly, the inner guide element 70 has a convex surface and a concave surface, both of which have a radius of curvature substantially equal to the distance IG from the inner guide element. In this way, the circumferential drag of the propulsion device is reduced.

[0050] The intermediate propulsion element 50 is longitudinally arranged at the center between the front propulsion element 30 and the rear propulsion element 40, and extends radially from the inner guide element 70 to the outer guide element 60. The intermediate propulsion element 50 has an intermediate inner end 51 fixed to the inner guide 70 and an intermediate outer end 52 fixed to the outer guide 60.

[0051] As can be understood from the above description, the front spacing member 35, the rear spacing member 45, the outer periphery of the hub 10, and the inner guide element 70 define an open space through which fluid (water in this example) can flow freely without generating any axial or circumferential resistance when the propulsion device rotates.

[0052] The front propulsion element 30, the rear propulsion element 40, and the intermediate propulsion element 50 have substantially the same geometry. At each propulsion element 30, 40, and 50, the leading edge is arranged substantially parallel to the trailing edge. Furthermore, the axial projection of the propulsion elements is substantially rhomboid. Additionally, the propulsion elements 30, 40, 50, the inner guide element 70, and the outer guide element 60 have substantially equal widths in the circumferential direction.

[0053] The circumferential width of the propulsion elements 30, 40, and 50 can also be represented by the length of the chord (or string) extending from the leading edge to the trailing edge through the respective propulsion element and the axial projection of that chord. Using the propulsion device according to this disclosure, compared to conventional propellers, a shorter chord and its axial projection can be maintained while still achieving satisfactory thrust. This is highly advantageous because a shorter or smaller chord reduces the risk of cavitation. It has been shown that the chord of the propulsion elements 30, 40, and 50 is preferably what is called a short chord or a small chord according to the NACA standard nomenclature.

[0054] Figure 3 A second embodiment of the propulsion device is shown, which includes a hub 110 and three propulsion devices 120 distributed along the outer periphery of the hub 110 and spaced 120° apart.

[0055] Figure 4 A third embodiment of the propulsion device is shown, which includes a hub 210 and four propulsion devices 220 distributed along the outer periphery of the hub 210 and spaced at 90° intervals.

[0056] exist Figure 3 and Figure 4 In the embodiment shown, the hubs 110, 210 and each propulsion device 120, 220 are substantially the same as... Figures 1 to 2c As shown and as described above, the hub 10 and the propulsion device 20 are the same, and will not be described again here.

[0057] In an embodiment not shown, each propulsion device may include one or more intermediate propulsion elements disposed between the front propulsion element and the rear propulsion element. Similarly, in this case, the intermediate propulsion element extends radially between an inner guide element and an outer guide element disposed at a distance from the hub, the outer guide element extending between the outer ends of the front and rear propulsion elements. In this embodiment, each propulsion device includes effective propulsion elements disposed between the inner and outer guide elements, the total number of which is equal to the number of intermediate propulsion elements plus two.

[0058] In another embodiment, not shown, each propulsion device may include two or more elongated, spaced members to connect the inner guide element to the hub.

[0059] In all the propulsion devices shown and described above, preferably, all propulsion elements in the propulsion device are longitudinally aligned and completely overlap each other in the longitudinal direction.

[0060] The foregoing has primarily described various aspects of the present invention in conjunction with several implementation methods and embodiments. However, those skilled in the art will readily understand that, in addition to the embodiments disclosed above, other embodiments are also within the scope of the present invention as defined by the appended patent claims.

Claims

1. A propulsion device for applying thrust to a fluid, the propulsion device comprising: A central hub (10, 110, 210) having a front end (11) and a rear end (12) and being rotatable about a rotation axis (A) extending longitudinally between the front end (11) and the rear end (12); and At least two propulsion devices (20, 120, 220) are radially projecting from the hub (10, 110, 210) and evenly distributed around the circumference of the hub (10, 110, 210), wherein each propulsion device (20, 120, 220) comprises: - A forward propulsion element (30) that extends radially from the front inner end (31) to the front outer end (32). - Rear propulsion element (40), which extends radially from the rear inner end (41) to the rear outer end (42). - An outer guide element (60) that maintains a radial outer guide element distance (OG) from the front outer end (32) to the rear outer end (42) with respect to the rotation axis (A). - Inner guide element (70), the inner guide element (70) is kept at a radial inner guide element distance (IG) from the front inner end (31) to the rear inner end (41) of the rotation axis (A). - An elongated front spacing member (35) and an elongated rear spacing member (45), the elongated front spacing member (35) and the elongated rear spacing member (45) extending radially from the hub (10) to the inner guide element (70), and - At least one intermediate propulsion element (50) is arranged between the front propulsion element (30) and the rear propulsion element (40) and extends radially from the inner guide element (70) to the outer guide element (60), wherein the longitudinal projections of the front propulsion element (30), the intermediate propulsion element (50) and the rear propulsion element (40) at least partially overlap, and wherein the outer periphery of the inner guide element (70), the front spacing member (35), the rear spacing member (45) and the hub (10) defines an open space that allows fluid to pass freely.

2. The propulsion device according to claim 1, wherein, The longitudinal projections of the front propulsion element (30), the middle propulsion element (50), and the rear propulsion element (40) completely overlap.

3. The propulsion device according to claim 1 or 2, wherein, The lengths of the axial projections of the chords of the front propulsion element (30), the rear propulsion element (40), and the intermediate propulsion element (50) are substantially constant.

4. The propulsion device according to claim 1, wherein, The maximum chord of each of the forward propulsion element (30), the rear propulsion element (40), and the intermediate propulsion element (50) is a short chord defined by extending a maximum 60% angular range.

5. The propulsion device according to claim 1, wherein, The radial inner guide element distance (IG) is at least 40% of the radial outer guide element distance (OG).

6. The propulsion device according to claim 1, wherein, The outer guide element (60) protrudes rearward from the rear outer end (42).

7. The propulsion device according to claim 1, wherein, The outer guide element (60) and / or the inner guide element (70) have a substantially constant longitudinal cross-section that bulges outward.

8. The propulsion device according to claim 1, wherein, The outer guide element (60) and / or the inner guide element (70) have a substantially constant longitudinal cross-section that is recessed inward.

9. The propulsion device according to claim 7, wherein, The convex or concave radius of curvature is substantially equal to the radial outer guide element distance (OG) or the radial inner guide element distance (IG) from the axis of rotation (A) to the corresponding outer guide element (60) and / or inner guide element (70).

10. The propulsion device according to claim 1, wherein, The distance between the leading and trailing edges of each of the front propulsion element (30), the rear propulsion element (40), and the intermediate propulsion element (50) is substantially constant along the radial extension of the front propulsion element (30), the rear propulsion element (40), and the intermediate propulsion element (50).

11. The propulsion device according to claim 1, wherein, The front spacing member (35) and the rear spacing member (45) are longitudinally aligned.

12. The propulsion device according to claim 1, wherein, The front spacing member (35) and the rear spacing member (45) are arranged to extend radially from the front inner end (31) and the rear inner end (41) to the hub (10), respectively.

13. The propulsion device according to claim 1, wherein, Each propulsion device includes multiple intermediate propulsion elements.

14. The propulsion device according to claim 1, wherein the propulsion device comprises: Two propulsion devices (20) spaced 180˚ apart in the circumferential direction; or Three propulsion devices (120°) spaced 120° apart in the circumferential direction; or Four propulsion devices (220) spaced 90˚ apart in the circumferential direction; or Five propulsion devices spaced 72˚ apart in the circumferential direction; or Six propulsion devices spaced 60˚ apart in the circumferential direction.

15. The propulsion device according to claim 5, wherein, The radial inner guide element distance (IG) is 40% to 75% of the radial outer guide element distance (OG).

16. The propulsion device according to claim 13, wherein, Each propulsion device includes two or three intermediate propulsion elements.

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