WO2021157675A1

WO2021157675A1 - Propeller blade-to-hub coupler for an unmanned aerial vehicle

Info

Publication number: WO2021157675A1
Application number: PCT/JP2021/004187
Authority: WO
Inventors: Emil Ghapgharan
Original assignee: Hapsmobile Inc.
Priority date: 2020-02-04
Filing date: 2021-02-04
Publication date: 2021-08-12

Abstract

Systems, devices, and methods including a propeller comprising at least one first mating surface; a blade-to-hub coupler comprising at least one second mating surface, where the blade-to-hub coupler is positioned at a base of the propeller, and where the at least one second mating surface of the blade-to-hub coupler mates with the at least one first mating surface of the propeller to connect the blade-to-hub coupler to the propeller.

Description

PROPELLER BLADE-TO-HUB COUPLER FOR AN UNMANNED AERIAL VEHICLE

　　Embodiments relate generally to propeller blade-to-hub couplers, and more particularly to a propeller blade-to-hub coupler for an unmanned aerial vehicle.

Summary

　　A system embodiment may include: a propeller comprising at least one first mating surface; a blade-to-hub coupler comprising at least one second mating surface, where the blade-to-hub coupler may be positioned at a base of the propeller, and where the at least one second mating surface of the blade-to-hub coupler mates with the at least one first mating surface of the propeller to connect the blade-to-hub coupler to the propeller.

　　In additional system embodiments, the at least one second mating surface may be one or more splines. In additional system embodiments, the at least one first mating surface may be one or more teeth. In additional system embodiments, the at least one first mating surface may be smooth, and the at least one second mating surface may be smooth. In additional system embodiments, the blade-to-hub coupler may be made of high strength stainless steel. In additional system embodiments, the propeller may be made from at least one of: Kevlar, carbon fiber, fiberglass, and foam. In additional system embodiments, the at least one first mating surface and the at least one second mating surface prevent twisting between the base of the propeller and the blade-to-hub coupler.

　　In additional system embodiments, the blade-to-hub coupler may further include: a base; a body disposed distal from the base; a first tapered portion extending away from the base; a second tapered portion extending away from the body; and a ringed portion disposed between the first tapered portion and the second tapered portion. In additional system embodiments, the ringed portion may provide a centrifugal load transfer connection to the first tapered portion. In additional system embodiments, the body of the blade-to-hub coupler may include a lower portion proximate the second tapered portion and an outwardly-tapered portion distal from the second tapered portion.

　　In additional system embodiments, the blade-to-hub coupler may be hollow. Additional system embodiments may include an adhesive connecting the at least one first mating surface and the at least one second mating surface.

　　The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the invention. Like reference numerals designate corresponding parts throughout the different views. Embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which:
[Fig. 1] FIG. 1 depicts a propeller and a propeller blade-to-hub coupler of an unmanned aerial vehicle;
[Fig. 2] FIG. 2 depicts a cross-sectional view of the propeller and propeller blade-to-hub coupler of FIG. 1;
[Fig. 3] FIG. 3 depicts a rear perspective view of the propeller blade-to-hub coupler of FIG. 1;
[Fig. 4] FIG. 4 depicts a top perspective view of the propeller blade-to-hub coupler of FIG. 1;
[Fig. 5] FIG. 5 depicts a side perspective view of the propeller blade-to-hub coupler of FIG. 1;
[Fig. 6] FIG. 6 depicts a side perspective view of the propeller blade-to-hub coupler of FIG. 1;
[Fig. 7] FIG. 7 depicts cross-sectional views of the propeller blade-to-hub coupler of FIGS. 1-6; and
[Fig. 8] FIG. 8 depicts a cross-sectional views of the propeller blade-to-hub coupler of FIG. 7 enhanced in a detail C and along a line B-B showing splines of the propeller blade-to-hub coupler.

　　With respect to FIG. 1, a propeller blade-to-hub coupler 100 for a propeller 101 (partially shown) of an unmanned aerial vehicle (UAV) is depicted. UAVs are aircraft with no onboard pilot and may fly autonomously or remotely. In one embodiment, the UAV is a high altitude long endurance aircraft. In one embodiment, the UAV may have one or more motors, for example, between one and forty (40) motors, and a wingspan between one hundred (100) feet and four hundred (400) feet. In one embodiment, the UAV has a wingspan of approximately two hundred sixty (260) feet and is propelled by a plurality of propellers 101 coupled to a plurality of motors, for example, ten (10) electric motors, powered by a solar array covering the surface of the wing, resulting in zero emissions. Flying at an altitude of approximately sixty five thousand (65,000) feet above sea level and above the clouds, the UAV is designed for continuous, extended missions of up to months without landing.

　　The UAV functions optimally at high altitude and is capable of considerable periods of sustained flight without recourse to land. In one embodiment, the UAV may weigh approximately three thousand (3,000) lbs.

　　In one embodiment, the propeller blade-to-hub coupler 100 is positioned at a base 103 of the propeller 101. More specifically, a propeller hub inside the base of the propeller 101 may clamp onto the propeller blade-to-hub coupler 100 for connection of the propeller blade-to-hub coupler 100 to the propeller 101. The propeller blade-to-hub coupler 100 may have a plurality of splines 120. In one embodiment, the splines 120 may mate to teeth of the hub of the propeller 101. In another embodiment, the mating surfaces of the propeller blade-to-hub coupler 100 and the propeller hub are smooth (e.g., where the propeller hub clamps onto the propeller blade-to-hub coupler). In one embodiment, the blade-to-hub coupler 100 is made of high strength stainless steel.

　　Generally speaking, it is a challenge to bond ferrous materials to composites (e.g., carbon fiber); this is because the ferrous materials and the composite materials have very different coefficients of thermal expansion (CTEs). The difference in CTE can cause delamination between the mating faces of the parts when exposed to large temperature variations, such as climbing to high altitude (even when an appropriate adhesive is used to bond the dissimilar materials). The splines 120 provide the mechanical means of interlocking the composite propeller 101 to the ferrous blade-to-hub coupler. The composite propeller 101 may be made of Kevlar, carbon fiber, fiberglass, and filled with foam. The composite base 103 of the propeller 101 may be composed of Kevlar, carbon fiber and fiberglass. The splines 120 may also prevent unwanted twisting between the base 102 and the blade-to-hub coupler 100.

　　With respect to FIG. 2, the propeller blade-to-hub coupler connected to the propeller 101 are shown in cross section. In one embodiment, a ring 105 is positioned and configured to keep the composite base 103 from splitting open circumferentially as the load increases with the spinning propeller.

　　With respect to FIGS. 3-6, the propeller blade-to-hub coupler 100 may include a base 102 and a body 110. A first tapered portion 104 may extend from the base 102 to a ringed portion 106. A second tapered portion 108 may extend from the ringed portion 106 to the body 110. The ringed portion 106 may be configured to provide a centrifugal load transfer bridge/connection to the first tapered portion 104. Without the second tapered portion 106, the propeller blade may fly outward and slip out of the propeller hub as the motor speed increases. The body 110 may include a lower portion 112 and an upper, outwardly-tapered portion 114. In one embodiment, the base 102, the lower portion 112, and the upper portion, outwardly-tapered portion 114 hold the propeller 101 steady in the plane of rotation when clamped in the hub.

　　In one embodiment, the propeller blade-to-hub coupler 100 is hollow and made of stainless steel with a material thickness of approximately 0.05 ± 0.01 inches. In one embodiment, the propeller blade-to-hub coupler 100 is approximately 2.725 ± 0.005 inches in length. In one embodiment, the length of the upper portion 114 is approximately 1.186 ± 0.005 inches long. In one embodiment, the propeller blade-to-hub coupler 100 weighs approximately 51 grams (10%). In one embodiment, the upper portion 114 has an opening angle of 9.7° ± 1.0°.

　　The propeller blade-to-hub coupler 100 may have splines 120 that keep the propeller 101 from rotating. The splines 120 may further allow for a higher capacity of the load to be transferred to the propeller blade-to-hub coupler 100 by mechanically interlocking the propeller 101 to the blade-to-hub coupler 100. The interlocking of the propeller 101 to the blade-to-hub coupler 100 gives the joint greater strength than just a joint made with adhesive, especially when exposed to large temperature changes, such as temperature changes within a range between -85°C and +60°C. More specifically, the propeller blade-to-hub coupler 100 may transfer the propeller gyroscopic and aerodynamic loads to the propeller hub.

　　Generally speaking, the UAV may fly at a wide range of altitudes with varying ambient temperatures. In one embodiment, there may be both a glue connection and a mechanical connection of the propeller blade-to-hub coupler 100 to the propeller 101; therefore, attachment of the propeller blade-to-hub coupler 100 to the propeller 101 may be maintained even when large temperature changes occur.

　　With respect to FIG. 8, the splines 120 are shown in greater detail. More specifically, the left-hand panel depicts the splines 100 in cross section along a line B-B shown in the right panel of FIG. 7. In one embodiment, each spline 120 has a width of 0.125 ± 0.002 inches. In one embodiment, the hub of the propeller 101 may have an accompanying tooth to fit into each spline 120 creating a mechanical connection of the propeller blade-to-hub coupler 100 to the propeller 101. In one embodiment, there may also be a glue connection of the propeller blade-to-hub coupler 100 to the propeller 101. Configured as such, the splines 120 may keep the propeller 101 from rotating if a bond failure were to occur between the composite and the blade-to-hub coupler 100.

　　With respect to the right-hand panel depicted in FIG. 8, a profile of a spline 120 is shown. More specifically, an enhanced cross-sectional view taken as detail C of the left-hand panel of FIG. 7 is illustrated. As described above, the thickness of the walls of the propeller blade-to-hub coupler 100 are approximately 0.05 ± 0.01 inches. In one embodiment, each spline 120 has a depth of approximately 0.02 ± 0.002 inches throughout the upper portion 114 of the body 110 of the propeller blade-to-hub coupler 100. In the lower portion 112 of the body 110, the depth of the spline 120 may taper to a shallower depth towards the end of the spline 120. In one embodiment, the taper in the blade-to-hub coupler 100 provides a wedge against the propeller blade shape. This is analogous to a system of a cone within another cone, where a cone cannot be pulled thru another cone without breaking it. The taper in the blade-to-hub coupler 100 reacts against the taper in the propeller blade as the propeller spins, therefore keeping the blade from sliding off the blade-to-hub coupler 100. The gyroscopic and aerodynamic loads generated by the propeller are reacted by all the geometric features in the blade-to-hub coupler 100.

　　The blade-to-hub coupler 100 provides for the blade angle of the propeller 101 to be adjusted when the UAV is on the ground and when the associated engine is not running. On the ground, the blades may be loosened in the propeller hub and the blade angle may be adjusted. A new blade angle may be set and the hub may be tightened to the propeller 101 with the blade-to-hub coupler 100.

　　It is contemplated that various combinations and/or sub-combinations of the specific features and aspects of the above embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another in order to form varying modes of the disclosed invention. Further, it is intended that the scope of the present invention is herein disclosed by way of examples and should not be limited by the particular disclosed embodiments described above.

Claims

　　A system comprising:
　　a propeller comprising at least one first mating surface;
　　a blade-to-hub coupler comprising at least one second mating surface, wherein the blade-to-hub coupler is positioned at a base of the propeller, and wherein the at least one second mating surface of the blade-to-hub coupler mates with the at least one first mating surface of the propeller to connect the blade-to-hub coupler to the propeller.
　　The system of claim 1, wherein the at least one second mating surface is one or more splines.
　　The system of claim 2, wherein the at least one first mating surface is one or more teeth.
　　The system of claim 3, wherein the one or more teeth fit into the one or more splines and create a mechanical connection of the blade-to-hub coupler to the propeller.
　　The system of any one of claims 1 to 4, wherein the at least one first mating surface is smooth, and wherein the at least one second mating surface is smooth.
　　The system of any one of claims 1 to 5, wherein the blade-to-hub coupler is made of high strength stainless steel.
　　The system of any one of claims 1 to 6, wherein the propeller is made from at least one of: Kevlar, carbon fiber, fiberglass, and foam.
　　The system of any one of claims 1 to 7, wherein the at least one first mating surface and the at least one second mating surface prevent twisting between the base of the propeller and the blade-to-hub coupler.
　　The system of any one of claims 1 to 8, wherein the blade-to-hub coupler further comprises:
　　a base;
　　a body disposed distal from the base;
　　a first tapered portion extending away from the base;
　　a second tapered portion extending away from the body; and
　　a ringed portion disposed between the first tapered portion and the second tapered portion.
　　The system of claim 9, wherein the ringed portion provides a centrifugal load transfer connection to the first tapered portion.
.　　The system of claim 9 or 10, wherein the body of the blade-to-hub coupler comprises a lower portion proximate the second tapered portion and an outwardly-tapered portion distal from the second tapered portion.
　　The system of claim 11, wherein the depth of the spline is taper to a shallower depth towards the end of the spline in the lower portion.
　　The system of any one of claims 1 to 12, wherein the blade-to-hub coupler is hollow.
　　The system of any one of claims 1 to 13, further comprising an adhesive connecting the at least one first mating surface and the at least one second mating surface.