Systems, methods, and devices for a tiltrotor vehicle

Abstract

A pitch control system includes a boom (140, 142) and a rotor (130, 132, 230) pivotally connected to the boom, the rotor being tiltable between a first position and a second position and between intermediate positions, the rotor having blades (175), where the blades are configured to adjust pitch. The pitch control system includes a base (188) connected to the distal end of the boom (140, 142), the base being rotationally stationary, a mount (186) connected to the base, and an actuation member (164). The actuation member is operatively connected with the mount and with the blades (175), the actuation member configured to move relative to the mount (186) in a first direction and in a second direction, the actuation member being configured to move with the rotor (130, 132, 230) when the rotor tilts such that, as the rotor transitions between the first position and the second position, the pitch of the blades is adjusted by the actuation member moving relative to the mount.

Description

SYSTEMS, METHODS, AND DEVICES FOR A TILTROTOR VEHICLECROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 634,718, filed April 16, 2024, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] Embodiments of this disclosure are directed to vehicle operation, and in particular, to systems and methods for changing blade pitch of aircraft.BACKGROUND OF THE INVENTION

[0003] Transitions between high-speed and low-speed flight of hybrid vertical takeoff and landing vehicles (VTOL) result in a significant change in how forces are imparted from the rotors and control surfaces to the vehicle. Due to these changes, the vehicle operator may make more precise movements at low-speeds in which vertical lift is generated by rotors and provide inputs that seek to maintain speed, orientation, and / or direction at higher speeds.

[0004] Some types of VTOL aircraft, such as helicopters, are effective at creating vertical lift. However, some VTOL aircraft have reduced horizontal thrust capability and are not easily scalable to move persons or goods over longer distances efficiently. With regards to VTOL aircraft having multiple rotors for creating vertical lift, such VTOL aircraft may include systems to change the position of the tilt rotors between vertical and horizontal orientations. To control the transition of VTOL aircraft between high speed and low speed flight modalities, changing the pitch of the rotor blades is desirable for producing the appropriate amount of thrust. However, systems for accomplishing these tasks are relatively complex and heavy.

[0005] There is a need for a system to adjust rotor pitch, for example during transition of a tiltrotor aircraft between rotorborne and wingborne flight.SUMMARY OF THE DISCLOSURE

[0006] The present disclosure generally provides for a pitch control system configured to be used with an aircraft, the system including a boom having an end portion and a rotor pivotally connected to the distal end portion of the boom, the rotor being tiltable between a first position and a second position and between a plurality of intermediate positions, the rotor having a plurality of blades, where the plurality of blades are configuredto adjust pitch. The pitch control system may also include a pitch change assembly including a base connected to the distal end of the boom, the base being rotationally stationary, a mount connected to the base, and an actuation member. The actuation member may be operatively connected with the mount and with the plurality of blades, the actuation member configured to move relative to the mount in a first direction and in a second direction, the actuation member being configured to move with the rotor when the rotor tilts such that, as the rotor transitions between the first position and the second position, the pitch of the plurality of blades is adjusted by the actuation member moving relative to the mount.

[0007] The present disclosure also provides for a pitch motion control system configured to be used with a tiltrotor aircraft, the pitch motion control system operatively connected with a plurality of blades and configured to adjust the pitch of the plurality of blades. The pitch motion control system may include a base connected to a distal end portion of a boom, a mount connected to the base and including a profile, and an actuation member. The actuation member may be operatively connected with the mount and with the plurality of blades, the actuation member configured to follow the profile of the mount and to move relative to the mount in a first direction, in a second direction, and between a first position and a second position with a plurality of intermediate positions between the first position and the second position. Where the actuation member moves between the first position and the second position, the pitch of the plurality of blades may be adjusted by the actuation member moving in the first direction and / or the second direction.

[0008] The present disclosure also provides for a method, including rotating a plurality of blades of a rotor while an actuation member is in a first position, the plurality of blades having a first pitch and moving the actuation member from the first position to a second position by tilting the rotor about a tilt axis, the actuation member tilting with the rotor. The method may also include changing pitch of the plurality of blades to a second pitch as the actuation member tilts with the rotor, the actuation member being movably connected to a mount, a position of the actuation member relative to the mount causing motion of the actuation member in a first direction away from the tilt axis or in a second direction toward the tilt axis and rotating the plurality of blades at the second pitch while the actuation member is in the second positionBRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various examples and, together with the description, serve to explain the principles of the disclosed examples and embodiments.

[0010] Aspects of the disclosure may be implemented in connection with embodiments illustrated in the attached drawings. These drawings show different aspects of the present disclosure and, where appropriate, reference numerals illustrating like structures, components, materials, and / or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, and / or elements, other than those specifically shown, are contemplated and are within the scope of the present disclosure.

[0011] Moreover, there are many embodiments described and illustrated herein. The present disclosure is neither limited to any single aspect or embodiment thereof, nor is it limited to any combinations and / or permutations of such aspects and / or embodiments. Moreover, each of the aspects of the present disclosure, and / or embodiments thereof, may be employed alone or in combination with one or more of the other aspects of the present disclosure and / or embodiments thereof. For the sake of brevity, certain permutations and combinations are not discussed and / or illustrated separately herein. Notably, an embodiment or implementation described herein as “exemplary” is not to be construed as preferred or advantageous, for example, over other embodiments or implementations; rather, it is intended to reflect or indicate the embodiment s) is / are “example” embodiment(s).

[0012] FIG. 1 A illustrates a vertical takeoff vehicle in a first configuration.

[0013] FIG. IB illustrates a vertical takeoff vehicle in a second configuration.

[0014] FIG. 2 illustrates a schematic view of a boom with rotors in a vertical position, according to the present disclosure.

[0015] FIG. 3 illustrates a cross-sectional view of one example of a pitch control system according to the present disclosure.

[0016] FIGS. 4A and 4B illustrate a first position and a second position of the pitch control system according to the present disclosure.

[0017] FIGS. 5 A and 5B illustrate a first position and a second position of a tilt motion control system according to the present disclosure.

[0018] FIGS. 6A-6D illustrate examples of pitch control as the tilt motion control system transitions from a first position to a second position through a plurality of intermediate positions.

[0019] FIG. 7 A illustrates another example of a tilt motion control system in a first position according to the present disclosure.

[0020] FIG. 7B illustrates the tilt motion control system of FIG. 7A in a second position.

[0021] FIG. 8 illustrates example pitch control as the tilt motion control system transition from a first position to a second position through a plurality of intermediate positions.

[0022] FIG. 9 illustrates a flow chart corresponding to a method of controlling blade pitch.

[0023] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. The term “exemplary” is used in the sense of “example,” rather than “ideal.” In addition, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish an element or a structure from another. Moreover, the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of one or more of the referenced items.

[0024] Notably, for simplicity and clarity of illustration, certain aspects of the figures depict the general structure and / or manner of construction of the various embodiments. Descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring other features. Elements in the figures are not necessarily drawn to scale; the dimensions of some features may be exaggerated relative to other elements to improve understanding of the example embodiments. For example, one of ordinary skill in the art appreciates that the side views are not drawn to scale and should not be viewed as representing proportional relationships between different components. The side views are provided to help illustrate the various components of the depicted assembly, and to show their relative positioning to one another.DETAILED DESCRIPTION

[0025] Reference will now be made in detail to examples of the present disclosure, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. In the discussion that follows, relative terms such as “about,” “substantially,” “approximately,” etc.are used to indicate a possible variation of a numerical range in a stated numeric value, as will be designated below

[0026] The present disclosure generally provides for systems, methods, and devices of a vertical takeoff and landing (VTOL) aircraft at various speeds, modes, and phases of flights to control position, orientation, direction, and / or speed of the VTOL aircraft. Although the present disclosure makes reference to a VTOL aircraft, those of ordinary skill in the art will readily recognize that reference to an aircraft is exemplary, and that the concepts of the present disclosure may be used in conjunction with any suitable or comparable aircraft, e.g., airplanes, helicopters, aerostats, flight simulators, space crafts, commercial airplanes, electrical vertical takeoff and landing aircrafts (eVTOL aircrafts), or any other type of tilt rotor aircraft. Still further, aspects of the present disclosure may be used in conjunction with any vehicle, including, but not limited to, vehicles designed for operation on land, on water, in the air, in space, or any combination thereof. The above list is not, in any matter, supposed to signify a limited list of what the term “aircraft” defines in terms of structure.

[0027] Turning to Figures 1 A and IB, perspective views of an exemplary hybrid VTOL tiltrotor aircraft 102 (herein aircraft 102), according to one or more embodiments, is provided. Aircraft 102 may function to travel short and long distances to provide transportation to passengers, luggage, cargo, and / or other objects that one of ordinary skill in the art will appreciate. Aircraft 102 may include a fuselage 104, front wings 106, rear wings 107, tilt- capable rotors 130, 132, 230, fixed rotors 133, and control surfaces 134. Aircraft 102 may be an eVTOL aircraft and include one or more batteries located within fuselage 104.

[0028] As can be seen in Figures 1A and IB, fuselage 104 may function as a body of aircraft 102 and support front wings 106, rear wings 107, tilt-capable rotors 130, 132, 230, fixed rotors 133, and control surfaces 134. Fuselage 104 may include cockpit 108, as well as an interior volume configured to house passengers, cargo, the like, or a combination thereof.

[0029] Front wings 106 may be connected with a forward portion of fuselage 104. Rear wings 107 may be connected with an aft portion of fuselage 104. Front wings 106 and rear wings 107 may function to assist aircraft 102 during flight by providing lift as the aircraft travels through the air during wingbome flight. In some examples, front wings 106 and rear wings 107 may connect tilt-capable rotors 130, 132, 230 and fixed rotors 133, as well as, control surfaces 134 to the fuselage 104. As will be described below, control surfaces 134 are connected to the front wings 106, rear wings 107, or both to assist in maneuvering.

[0030] Each of the front wings 106 and rear wings 107 are connected with one or more booms 140, 142. Each boom 140, 142 may be configured to support tilt-capable rotors 130,132, 230 and / or fixed rotors 133 at a distal end portion of boom 140, 142. In Figures 1A and IB, booms 140 pivotally support at least one of rotors 130, 132, and booms 142 support rotors 230. For example, in Figure 1 A, tilt-capable rotors 130, 132, 230 are in a vertical position (e.g., with an axis of rotation of each rotor being generally aligned with a vertical direction) corresponding to a rotorbome configuration 150, and in Figure IB, tilt-capable rotors 130, 132, 230 are in a horizontal position (e.g., with an axis of rotation of each rotor being generally aligned with a horizontal direction) corresponding to a wingborne configuration 152.

[0031] Control surfaces 134 may be connected with the front wings 106 and / or rear wings 107, boom 140, 142, or any other surface of aircraft 102 to assist with controlling aircraft 102 during takeoff, landing, and / or flight. In some examples, control surfaces 134 may be connected with fuselage 104. In some examples, control surfaces 134 may be connected with rotors 130, 132, 230, boom 140, 142, or both. Control surfaces 134 may function to assist with maneuvering aircraft 102 during flight. Control surfaces 134 may be elevators, rudders, ailerons, ruddervators, flaperons, trim, nacelle, flaps or any other control surfaces known to one of ordinary skill in the art. Control surfaces 134 may be configured to assist with moving aircraft 102 in a plurality of degrees of freedom. Control surfaces 134 may be configured to assist with converting aircraft 102 between rotorbome configuration 150 and wingborne configuration 152.

[0032] Tilt-capable rotors 130, 132, 230 (also referred to more simply as “rotors” 130, 132, 230) may be connected with the front wings 106, rear wings 107, or both. In some examples, rotors 130, 132, 230 may be connected with fuselage 104. Rotors 130, 132, 230 may be a propulsion source to move aircraft 102. Rotors 130,132, 230 may be connected with one or more motors for powering the rotors 130, 132, 230 to produce thrust. In some examples, rotors 130, 132, 230 may pivot or tilt relative to the front wings 106, rear wings 107, or both to transition between the horizontal position and the vertical position. In some examples, aircraft 102 may only have rotors 130, 132, and / or 230 as a propulsion source. In other examples, rotors 130, 132, 230 may be used in combination with other sources of propulsion, such as fixed rotors 133, jet engines, the like or a combination thereof. Rotors 130, 132, 230 may provide a primary thrust for takeoff and landing when in the vertical position, as well as the thrust required to sustain altitude and velocity when in the horizontal position. In some examples, aircraft 102 may include two or more rotors 130, 132, 230. In one example, such as shown in Figures 1A-1B, aircraft 102 includes rotors 130, 132 connected to front wings 106 on each side of the aircraft 102 with rotors 130, 132 located on boom 140, 142 and rotors 230 located on boom 142 on rear wings 107. It will be appreciated that even numbers of rotors 130,132, 230 may be provided. Rotors 130, 132, 230 may be configured to assist with moving aircraft 102 in a plurality of degrees of freedom.

[0033] Fixed rotors 133 may be connected with front wings 106, rear wings 107, or both. In some examples, fixed rotors 133 may have a fixed axis of rotation such that rotors 133 are always rotating parallel to vertical axis 110. In some other examples, fixed rotors 133 may be positioned in vertical positions, horizontal positions, or both. Fixed rotors 133 may be a propulsion source to move aircraft 102. In other examples, fixed rotors 133 may be positioned to rotate parallel to longitudinal axis 112. In other examples, a combination of fixed rotors 133 positioned with their axis of rotation parallel to vertical axis 110 and positioned with their axis of rotation parallel to longitudinal axis 112 may be used. Rotors 133 may provide thrust to VTOL aircraft 102 during takeoff and landing, and may further provide enhanced maneuverability for aircraft 102. In some examples, aircraft 102 may include any number of fixed rotors 133. In one example, such as shown in Figures 1A and IB, aircraft 102 includes two fixed rotors 133 connected with front wings 106. Fixed rotors 133 may be configured to assist with moving aircraft 102 in one or more degrees of freedom.

[0034] In some examples, rotors 130, 132, 230 may be connected to front wings 106 and rear wings 107 through boom 140, 142. Boom 140, 142 may be a structure configured to support rotors 130, 132, 230, control surfaces, mechanical systems, the like, or a combination thereof. Boom 140 may be a structure configured to extend past each end of front wing 106 to support rotors 130, 132, control surfaces 134, motors 158, the like or a combination thereof. Each boom 140 may be formed as a continuous body extending beyond the front and the rear of front wing 106, such that a first distal end is in front of wing 106 and a second distal end is behind wing 106. In other configurations, each boom 140 may be discontinuous, with separate front and rear portions that are not directly connected to each other, these front and rear portions forming first and second ends in front of and behind wing 106. As used herein, “boom” refers to booms with continuous structures and booms with discontinuous structures. Boom 142 may connect rotors 230 to rear wings 107.

[0035] Rotors 130, 132, 230 may include pylons 160 configured to support a motor 158 with blades 175. In some examples, pylons 160 may be structures configured to connect rotors 130, 132, 230, with boom 140, 142. As described further below, pylons 160 may be configured to transition between a vertical position corresponding to rotorborne configuration 150 and a horizontal position corresponding to wingborne configuration 152. In some examples, rotors 130, 132 may be connected to motors 158 that are housed by pylons 160 (Figures 2 and 3).

[0036] Figure 1A illustrates aircraft 102 in one example of the first configuration, a rotorborne configuration 150 (also known as a VTOL configuration). Figure 1 A depicts aircraft 102 and vertical axis 110, longitudinal axis 112, lateral axis 114, which aircraft 102 may translate and / or rotate about. In rotorborne configuration 150, rotors 130, 132, 230 are shown in a vertical direction, such that rotors 130, 132, 230 are positioned with their axis of rotation parallel to vertical axis 110 (also referred to as the x-axis; yaw axis). Aircraft 102 may travel generally up or down vertical axis 110 at various times throughout a flight (e.g., during climbing, descending, takeoff, and / or landing). Aircraft 102 may also rotate about vertical axis 110 (also referred to as the x-axis; yaw axis) as shown by rotation arrow 120 for a yaw movement. Aircraft 102 may also move along longitudinal axis 112 (also referred to as the y- axis; roll axis) generally backward or forward. Aircraft 102 may rotate (roll) relative to longitudinal axis 112 as shown by rotation arrow 122. Aircraft 102 may travel along lateral axis 114 (e.g., translate), as well as rotate about lateral axis 114 (also referred to as the z-axis; pitch axis) to cause a pitch movement, as shown by rotation arrow 124.

[0037] Turning now to Figure IB, aircraft 102 is illustrated in the wingborne configuration 152 with each of the rotors 130, 132, 230 arranged with their axis of rotation parallel to longitudinal axis 112. Similar to Figure 1 A, aircraft 102 is capable of moving along each of vertical axis 110, longitudinal axis 112, and lateral axis 114. In the wingborne configuration 152, aircraft 102 may travel generally forwards along longitudinal axis 112 and may also roll about longitudinal axis 112 as shown by rotation arrow 122. In wingborne configuration 152, aircraft 102 may rotate about lateral axis 114 (e.g., pitch up; pitch down). Aircraft 102 may climb up and down along vertical axis 110, as well as also rotate about vertical axis 110 as shown by rotation arrow 120 causing a yaw movement of aircraft 102.

[0038] As illustrated in Figures 1 A and IB, aircraft 102 may be configured to maneuver in a plurality of degrees of freedom. In this example, aircraft 102 may be configured to move in six degrees of freedom. Aircraft 102 may be configured to translate along each of vertical axis 110, longitudinal axis 112, and lateral axis 114. Similarly, aircraft 102 may be configured to rotate about each of vertical axis 110, longitudinal axis 112, and lateral axis 114, shown as rotation arrow 120, rotation arrow 122, and rotation arrow 124, respectively.

[0039] When aircraft 102 is in rotorborne configuration 150, aircraft 102 may operate at a low speed. In some examples, a low speed may refer to aircraft 102 traveling at a rate of 0 Knots to 50 Knots. However, in some other examples, “low speed” may be between 0 Knots and 150 Knots or more. For example, rotors 130, 132, 230, along with static rotors 132, may be used for vertical thrust (when aircraft 102 is in rotorborne configuration 150). In rotorborneconfiguration 150, control surfaces, along with a landing gear (not shown) may be extended and / or engaged.

[0040] When aircraft 102 is in wingborne configuration 152, aircraft 102 may travel at high speed. High speed may refer to movement during cruise, long distance travel, or similar. High speed may be a relative range between a speed higher than the low-speed range and a maximum speed of the craft. In some non-limiting examples, high speed may be between 30 knots and 150 Knots. In other non-limiting examples, the high speed range may be between 30 Knots or less and 450 Knots or more. For example, the rotors 130, 132, 230 may be used for horizontal thrust when in the wingborne configuration 152. In the wingborne configuration 152, one or more of control surfaces 134, landing gear, or other components may be retracted and / or concealed within aircraft 102.

[0041] Aircraft 102 may operate at a transitional speed. The transitional speed may be considered a “medium” speed and correspond to aircraft 102 transitioning between rotorbome configuration 150 and wingborne configuration 152. Put differently, transitional speed may be a speed at which the physical configuration of aircraft 102 changes such that the mechanism for generating lift on aircraft 102 changes. Additionally, a transitional speed may be a range of speeds which the control system of aircraft 102 may change the types of commands. For example, at a transitional speed, rotors 130, 132, 230 may be in the process of switching from generating primarily vertical thrust to primarily horizontal thrust.

[0042] A transitional speed may be any speed between low speed and high speed operation and / or configuration. In some examples, the transitional speed may be between 20 Knots and 60 Knots. In other examples, the transitional speed may be between 10 Knots and 120 Knots. In other examples, the transitional speed may be more than 120 knots. Multiple components of aircraft 102 may transition states while aircraft 102 operates at transitional speed. These components may include a combination of rotors 130, 132, 230 control surfaces, and / or landing gear(s). As examples, features such as spoilers, throttle, pitch control of rotors, rotor speed of rotors, any type of flaps, wing surfaces to resist rotation, rudders, etc., may be implemented to transition aircraft 102 from high speed to low speed.

[0043] As described above, aircraft 102 may transition between rotorbome configuration 150 to wingborne configuration 152 by transitioning rotors 130, 132, 230. With reference to Figure 2, in some examples, rotors 130, 132, 230 may be moved by a rotor tilting system 154 to move rotors 130, 132 between a vertical position corresponding to rotorbome configuration 150 and a horizontal position corresponding to wingborne configuration 152. In some examples, rotor tilting system 154 may include pylons 160, boom 140, 142, links, and apitch change assembly 166 (represented as a box in Figure 3 and described in greater detail below).

[0044] Rotor tilting system 154 may be configured to tilt each rotor 130, 132 relative to boom 140, 142. In some examples, pylons 160 may be configured to move with rotors 130, 132 between the vertical position (also referred to as the first position) corresponding with rotorborne configuration 150, and the horizontal position (also referred to as the second position) corresponding with wingborne configuration 152. Pylons 160 may be configured to support a motor 158, which is connected with rotors 130, 132. In some examples, each pylon 160 may house one or more drive motors 158. In some examples, pylons 160 may be pivotally connected to boom 140.

[0045] As described above, boom 140 may be connected with front wings 106. Boom 140 may be configured to support rotors 130, 132. Boom 140 may be configured as any suitable shape to support rotors 130, 132. Boom 140 may include a longitudinal axis extending between a first end and a second end. Boom 140 may include mounts which may be configured to connect with pylon 160. Each of the mounts may define a tilt conversion axis. The tilt conversion axis may be an axis which pylons 160 pivot about boom 140.

[0046] To assist with maneuvering aircraft 102 in rotorborne configuration 150 and wingborne configuration 152, rotor blades 175 may adjust their respective pitch as rotors 130, 132 are pivoted about boom 140 to tilt and transition between the configurations. As discussed above, aircraft 102 operates in different manners and at different speeds between rotorborne configuration 150 and wingborne configuration 152. For example, in rotorborne configuration 150, aircraft 102 may operate at a relatively low speed, with rotors 130, 132, 230 in the vertical position. Conversely, in wingborne configuration 152, aircraft 102 operates at relatively high speeds with rotors 130, 132 in the horizontal position. To facilitate the different flight characteristics of rotorborne configuration 150, wingborne configuration 152, and transitions between these configurations, the pitch of each rotor blade 175 may be adjusted.

[0047] With reference to Figure 3, pitch control system 156 may include a rotor hub 170, a shaft 162, a control plate 168, and an actuation member 164 (e.g., an actuation rod). A pitch change assembly 166, represented as a box in Figure 3, may work in conjunction with pitch control system 156 and / or as part of pitch control system 156. Pitch control system 156 may be operatively connected with motor 158 on pylon 160 (Figure 2).

[0048] Motor 158 may be configured to provide rotational movement to rotor blades 175 to spin rotor blades 175 to generate thrust. Motor 158 may be configured to pivot relative to boom 140, 142 in order to transition between rotorborne configuration 150 and wingborneconfiguration 152. In some examples, as shown in Figure 3, motor 158 is an electric motor. Motor 158 may be configured to rotate rotor shaft 162.

[0049] Rotor shaft 162 may be a hollow rod connected with motor 158 to provide rotational movement from motor 158 to rotor hub 170, spinning rotor blades 175. In some examples, rotor shaft 162 may be configured as an output shaft for motor 158, such that motor 158 rotates rotor shaft 162 to spin rotor hub 170, spinning rotor blades 175 to create thrust. Rotor shaft 162 may have a hollow interior that extends through rotor shaft 162 along a longitudinal axis. Rotor shaft 162 may be made from steel, alloy, composite, or a combination of materials which one of ordinary skill in the art would appreciate.

[0050] Rotor blades 175 may be connected with rotor hub 170. Rotor hub 170 may be configured to support at least a portion of rotor blades 175. Rotor hub 170 may include a base with an inner blade support 169, and an outer blade support 171 (Figure 3).

[0051] Rotor hub 170 may be configured to support one or more rotor blades 175. In some examples, rotor hub 170 may support two, three, four, five, or more, rotor blades 175. Each rotor blade 175 may include a root end portion 176 retained within rotor hub 170. As shown in Figure 3, the inner blade support 169 and outer blade support 171 may support each root end portion 176. Inner blade support 169 and outer blade support 171 may be configured as concentric rings to support each blade 175. Inner blade support 169 and outer blade support 171 may be spaced apart to support each blade 175 and allow blades 175 to rotate and change pitch.

[0052] With reference to Figures 4A and 4B, inner blade support 169 and outer blade support 171 may include bearings 173, 174 to assist with supporting blades 175 and allowing blades 175 to rotate to change pitch. Bearings 173, 174 may be journal bearings formed by inner blade support 169 and outer blade support 171. For example, bearing 173 may be located in inner blade support 169, and bearing 174 may be located in outer blade support 171. In some examples, when bearings 173, 174 are configured as journal bearings, rotor hub 170 may an oil-less system, which may increase performance and serviceability, since fluid does not need to fill the rotor hub 170 to keep bearings 173, 174 lubricated. In these and other configurations, bearings 173, 174 are formed by, or coated with, a low-friction material.

[0053] While journal bearings 173, 174 are shown, in some examples, bearings 173, 174 may include other types of bearings, such as roller bearings, thrust bearings, bushings, fluid bearings, or any other bearing type that one of ordinary skill in the art would appreciate. In some examples, bearing 173 may be a first type of bearing, and bearing 174 may be a secondtype of bearing. In other examples, both bearing 173 and bearing 174 are the same type of bearing.

[0054] Root end portions 176 of rotor blades 175 may be connected with a control plate 168. Control plate 168 may be configured to adjust the pitch of rotor blades 175. In some examples, control plate 168 may change the pitch of rotor blades 175 based on the position of control plate 168 in rotorbome configuration 150, wingbome configuration 152, and a plurality of positions between rotorborne configuration 150 and wingbome configuration 152. Control plate 168 may be configured to move in a first direction and a second direction, adjusting a distance between control plate 168 and rotor hub 170. In some examples, control plate 168 may be made of steel, alloy, composite, and / or a combination of materials which one of ordinary skill in the art would appreciate. Control plate 168 may be configured to rotate with rotor hub 170 and blades 175. Control plate 168 may include a base and a plurality of links. In some examples, links may extend downward from the annular base of plate 168. Links may be configured to connect with connectors 178 (also known as pitch horns).

[0055] With reference to Figure 4A, root end portions 176 of rotor blades 175 may each be connected with a connector 178, connector 178 following a generally arc-shaped path from root end portion 176 to control plate 168. Connector 178 may be configured to movably couple rotor blades 175 with control plate 168. In some examples, each connector 178 is fixedly secured to an end of a corresponding rotor blade 175. Connector 178 may include an arm, a first joint and a second joint. The first joint of connector 178 may connect with control plate 168, while the second joint connects with root end portion 176. Connector 178 may be made of steel, alloy, composite, the like, or a combination thereof.

[0056] Each arm of connector 178 may have a profile that assists in transferring movement from control plate 168 to rotor blades 175. For example, the arm may be straight, bent, tortuous, or have another type of shape to connect control plate 168 with rotor blades 175. In some examples, the arm may position the first joint and the second joint on the same plane. In other examples, the arm may position first joint and second joint on separate planes. The first joint may be configured to connect with a link of control plate 168 and may be configured to pivot about the link as control plate 168 is moved between positions. The second joint may be fixed with root end portion 176 such that as rotor blade 175 and connector 178 are fixed axially and moved together. The second joint of connector 178 may be keyed to root end portion 176. In other examples, an interference fit, a welded connection, a fastener connection, the like, or a combination thereof, may be used.

[0057] With reference to Figure 3, in some examples, actuation member 164 moves control plate 168 in upward and downward directions to adjust the pitch of each rotor blade 175. Actuation member 164 may be connected with pitch change assembly 166 and configured to move towards and away from rotor hub 170 as rotors 130, 132, 230 are moved between rotorborne configuration 150 and wingborne configuration 152, based on the current configuration of pitch change assembly 166, described in greater detail below.

[0058] Actuation member 164 may be connected with control plate 168 to move control plate 168, which, in turn moves connectors 178 so that rotor blades 175 are rotated to change pitch. Actuation member 164 may extend through rotor shaft 162 and motor 158. Actuation member 164 may be a rod, a shaft, a pipe, or any other suitable shape to extend through rotor shaft 162 and motor 158 to control plate 168. Actuation member 164 may be made from steel, alloy, composite, the like, or a combination thereof.

[0059] Actuation member 164 may be configured to remain rotationally stationary as control plate 168 rotates with rotor shaft 162 and rotor hub 170. To facilitate this connection, a bearing 172 in control plate 168 may be configured to receive actuation member 164. Bearing 172 may be a roller bearing, a bushing, a journal bearing, the like, or any other suitable bearing that one of ordinary skill in the art would appreciate.

[0060] Figures 4A and 4B illustrate one example of pitch control system 156 transitioning rotor blades 175 between a first position (e.g., vertical position 200) with a first pitch and a second position (e.g., horizontal position 202) with a second pitch. Figure 4A illustrates one example of pitch control system 156 with actuation member 164 at a first position. In some examples, the pitch of rotor blades 175 are positioned in rotorborne configuration 150 to generate vertical thrust (Figure 4A). The pitch of rotor blades 175 may be changed when rotors 130, 132, 230 are in wingborne configuration 152 to produce horizontal thrust to move aircraft 102 at a high rate of speed (Figure 4B).

[0061] In Figure 4A, control plate 168 is at a first position 200 with connectors 178 at a generally planar orientation. As can be seen in Figure 4A, control plate 168 is at a first distance DI from rotor hub 170. Figure 4B shows control plate 168 at second position 198 that is extended away from rotor hub 170 at a second distance D2 that is greater than first distance DI. In the examples shown in Figures 4A and 4B, by moving control plate 168 from first position corresponding to position 200 to a raised second position corresponding to position 202, control plate 168 rotates connectors 178 to rotate root end portion 176 of rotor blades 175, adjusting the pitch angle of rotor blades 175. Similarly, moving from wingborne configuration152 to rotorborne configuration 150 may move control plate 168 towards rotor hub 170 such that connectors 178 rotate root end portion 176 of blades 175 in an opposite direction.

[0062] Figures 5 A and 5B shown an example of pitch change assembly 166 of the pitch control system 156. Pitch change assembly 166 may be configured to actuate the actuation member 164 as rotors 130, 132, 230 transition between the vertical position 200 (Figure 5A) and the horizontal position 202 (Figure 5B). Pitch change assembly 166 may be configured to move actuation member 164 along a path that moves control plate 168 (Figures 3-4B) relative to the rotor hub 170, changing the pitch of rotor blades 175. Pitch change assembly 166 may cause the pitch of each of the rotor blades 175 to adjust in order to provide thrust based on the configuration of aircraft 102 or other parameters.

[0063] In one example, pitch change assembly 166 may include a mounting arm 196 (an example of a “mount”) and a drive link 194. Drive link 194 may be pivotally connected with the mounting arm 196 and with the actuation member 164. In some examples, as rotors 130, 132, 230 transition between positions, drive link 194 pivots about the mounting arm 196 pushing and / or pulling actuation member 164, causing control plate 168 to move relative to rotor hub 170 and change the pitch of rotor blades 175.

[0064] Pitch change assembly 166 may be connected with boom 140 (Figure 2) at boom mount 186. In some examples, base 188 may be connected with boom mount 186. Base 188 may be fixed in a fixed relationship with boom mount 186, such that base 188 does not rotate as pylon 160 transitions between the vertical position 200 and the horizontal position 202.

[0065] Pylon 160 is connected to boom 140 and rotates about boom mount 186 along a tilt path 190. As pylon 160 is pivots between positions, an end portion 316 of actuation member 164 also follows tilt path 190.

[0066] An actuator 180 may be connected with boom 140 and pylon 160 to move the pylon 160, as well as the pitch change assembly 166. Actuator 180 may be configured to extend and retract, which, in turn, may cause the pylon 160 to pivot about boom 140. In some examples, such as shown in Figures 5 A and 5B, actuator 180 may be a linear actuator. In other examples, other types of actuators may be used, such as a leadscrew actuator, a rotary actuary, or any other type of actuator that one of ordinary skill in the art would appreciate.

[0067] In Figure 5 A, actuator 180 is shown extended, with pylon 160 in the vertical position 200. In Figure 5B, actuator 180 is shown retracted, with pylon 160 in the horizontal position 202. To move between positions, actuator 180 may push or pull pylon 160. As pylon 160 is moved, actuation member 164 is moved along with pylon 160, causing actuationmember 164, along with drive link 194, to pivot about drive axis 184 of mounting arm 196, following link path 192.

[0068] Mounting arm 196 may extend from base 188 such that mounting arm 196 defines drive axis 184. Mounting arm 196 may extend from base 188 to drive axis 184. In some examples, such as shown in Figures 5 A and 5B, drive axis 184 is offset from tilt axis 182, such that axes 182 and 184 are not coaxial. This offset relationship may cause pitch of blades 195 to increase during part of a transition from vertical position 200 to horizontal position 202, and to decrease during other parts of the transition from vertical position 200 to horizontal position 202.

[0069] The location of drive axis 184 may assist with controlling changes to the pitch of rotor blades 175 as aircraft 102 transitions between rotorborne configuration 150 and wingborne configuration 152. For example, the mount formed by arm 196 may be sized, shaped, and positioned to achieve desired amounts of travel for actuation member 164 during this transition. Along with mounting arm 196 and drive axis 184, drive link 194 may be configured to assist with changing the pitch of rotor blades 175 between the vertical position 200 and the horizontal position 202, as described below.

[0070] Drive link 194 may rotate about drive axis 184 and may be connected with actuation member 164 to move the actuation member 164 as drive link 194 is rotated about drive axis 184. In some examples, drive link 194 may be configured to pivot about drive axis 184 while an end of drive link 194 follows link path 192 pylon 160 follows tilt path 190. Similar to the mounting arm 196, drive link 194 may be sized and shaped based on the amount of travel which actuation member 164 moves to adjust the pitch of rotor blades 175. In particular, the size and shape of mounting arm 196 and drive link 194 may define link path 192, as well as the distance between tilt path 190 and link path 192 that imparts changes of pitch to the rotor blades 175.

[0071] As can be seen in Figure 5 A, mounting arm 196 may support drive link 194 and actuation member 164 at a first distance 204 relative to tilt path 190 corresponding to the rotation of pylon 160 relative to boom 140 about tilt axis 182. In Figure 5B, pitch control system 156 has rotated with pylon 160 about tilt axis 182 into the horizontal position 202, traversing approximately 90 degrees or approximately 100 degrees along link path 192 while pylon 160 followed tilt path 190. In this example, drive link 194 is positioned at a second distance 206 relative to the tilt path 190 because the drive axis 184 is offset from the tilt axis 182.

[0072] The second distance 206 may be larger than the first distance 204. In some examples, drive link 194 pushes and / or pulls actuation member 164 between positions to adjust the pitch of rotor blades 175, such as seen in Figures 4A and 4B. In one example, the actuation member 164 causes the collective pitch of the plurality of blades to increase for a period of time and to decrease for a period of time as the rotor tilts from vertical position 200 to horizontal position 202 through the plurality of intermediate positions. This may also true for transitions from horizontal position 202 to vertical position 200. The location of drive axis 184 relative to the tilt axis 182, as well as the length of drive link 194, may determine link path 192 and, in turn, the pitch set with actuation member 164 during motion of pylon 160 along tilt path 190.

[0073] Figures 6A-6D show examples of pitch control between the vertical position 200 and the horizontal position 202. In particular, Figures 6A-6D show examples of pitch angle (y-axis) relative to rotor tilt angle (x-axis). In the example in Figure 6A, pitch angle may be about zero degrees when rotor tilt angle is at about zero degrees. As the rotor tilt angle increases, pitch angle decreases in a gradually accelerating manner approaching the limit of rotor tilt. The dashed plot in Figure 6A represents an alternative configuration where pitch angle varies from a positive angle to a negative angle.

[0074] Figure 6B illustrates an example with a different profile than Figure 6A, showing pitch angle increasing continuously until reaching an initial peak (a maximum pitch angle). As tilt angle increases and becomes more horizontal from this peak, the pitch angle decreases continuously. The alternative represented with a dashed plot shows tilt angle starting, and maintaining, a larger pitch angle.

[0075] Figure 6C illustrates another example, in which a relatively rapid reduction in pitch angle is experienced as rotor tilt begins to change. Figure 6C illustrates the ability of pitch change assembly 166 to achieve a relatively rapid change in pitch angle between vertical position 200 and horizontal position 202. In this example, pitch angle increases after reaching a minimum (e.g., negative) pitch angle value.

[0076] Figure 6D shows another example, with a relatively rapid increase in pitch angle occurring during an initial increase in rotor tilt angle. In this example, the pitch angle increases, and relatively quickly declines after reaching a peak at about 50% of the maximum rotor tilt angle. While Figures 6A-6D illustrate a series of examples (in solid and dashed plots), as understood, other examples are possible.

[0077] As mentioned previously, the pitch change assembly 166 may be designed for particular flight characteristics of aircraft 102 in order to achieve selected flight characteristics. In some examples, the pitch of the plurality of rotor blades 175 may be designed for carryingheavy loads on a large aircraft. In another example, the pitch of the plurality of rotor blades 175 may be designed for increased maneuverability, with less load capabilities. In another example, the pitch adjustment profile may be designed for speed with limited maneuverability during different flight modes.

[0078] Figures 7A and 7B illustrate another configuration of pitch change assembly 266. In this configuration, pitch change assembly 266 may include a cam or mount 294 connected with base 288. Base 288 may be connected with boom mount 286, such that base 288 does not rotate when pylon 160 moves between vertical and horizontal positions, as described above. Similar to the description of Figures 5A and 5B, pylon 160 tilts about tilt axis 282 causing actuation member 164 to move with pylon 160. As actuation member 164 is moved between positions, the bottom end of actuation member 164 follows a profile of mount 294. As actuation member 164 follows the profile of mount 294, actuation member 164 moves towards or away from rotation path 290. This motion of member 164 increases or decreases the distance between the end of actuation member 164 and rotation path 290.

[0079] In this example, actuation member 164 is connected with mount 294 such that actuation member 164 is retained at least partially by mount 294. As illustrated in Figures 7A and 7B, mount 294 may be a cam, and actuation member 164 may act as a follower (e.g., via a pin in the end of member 164 that travels along the surface of mount 294). Mount 294 may include a channel to receive actuation member 164 and allow actuation member 164 to be guided by a profile of the channel, sidewalls being defined on opposite sides of the channel. In some other examples, actuation member 164 may follow the contour of mount 294. Other methods of connection and control of movement are contemplated.

[0080] Figure 7A illustrates actuation member 164 at a first distance 208 from rotation path 290. The illustrated first distance 208 positions actuation member 164 at a location where member 164 is pushed out (upward in Figure 7A) relative to tilt axis 282. By moving actuation member 164 away from tilt axis 282, control plate 168 may be pushed by actuation member 164 away from rotor hub 170 (see Figure 4B).

[0081] Figure 7B illustrates pitch change assembly 266 in horizontal position 202 at which actuation member 164 is at second distance 210. This second distance 210 positions actuation member 164 at a location where member 164 is pulled in towards tilt axis 282. By moving actuation member 164 towards tilt axis 282, control plate 168 may be pulled by actuation member 164 towards rotor hub 170 (see Figure 4A).

[0082] As described above, mount 294 may be configured in a manner desirable for characteristics of a particular aircraft 102. To configure mount 294 for a particular application,the profile of mount 294 may be changed, these changes allowing control over whether member 164 is pushed or pulled relative to axis 282, and thus the ability to vary the pitch of rotor blades 175 as desired.

[0083] As an example of this control over the profile of mount 294, mount 294 is divided into three sections in Figures 7A and 7B that together form a profile of mount 294, including a first section 310, a second section 312, and a third section 314. The profile of mount 294 may be non-linear, resulting in a non-linear relationship between rotor tilt and collective pitch of blades 175. Figure 8 is a chart illustrating how the profile of mount 294 may affect pitch angle.

[0084] In Figure 8, pitch angle is represented as a function of tilt angle. Pitch angle may refer to the pitch of rotor blades 175, as in Figures 6A-6D. Tilt angle may refer to the angle of the rotor 130, 132, 230 (e.g., horizontal or vertical).

[0085] When rotor 130, 132, 230 begins in vertical position 200 and pivots to horizontal position 202, first section 310 may act to push member 164 away from axis 282, resulting in an increasing tilt angle as shown in the initial pitch angle increase in Figure 8. This may be a relatively rapid transition in pitch angle. The beginning of first portion 310 may correspond with rotorborne configuration 150.

[0086] Second section 312 may have a profile at which the distance between actuation member 164 and axis 282 remains approximately constant, causing pitch angle of the plurality of blades 175 to also remain approximately constant (e.g., Figure 8, showing a flat pitch angle). The second portion 312 may correspond with a transition of aircraft 102 moving between rotorborne configuration 150 and wingbome configuration 152.

[0087] Third portion 314 may cause actuation member 164 to gradually move toward axis 282. In the example shown in Figure 8, this may correspond to the decrease in pitch angle. When the actuation member 164 is in third section 314 of the profile of mount 294, aircraft 102 may be in wingbome configuration 152.

[0088] The pitch angle may change by approximately 5 degrees, approximately 10 degrees, approximately 15 degrees, approximately 20 degrees, approximately 25 degrees, or more. While Figure 8 illustrates one example profile of pitch angle relative to tilt angle, other profiles, such as shown in Figures 6A-6D, and others, may be achieved with pitch change assembly 266.

[0089] Figure 9 illustrates one example of a method 300 for controlling the pitch of rotors 130, 132, 230. At a step 302, rotors 130, 132, 230 may rotate rotor blades 175 at a firstposition, while the rotor blades 175 are at a first pitch. This first pitch may be associated with the position 200 shown in Figures 5A and 7A.

[0090] At step 304, to transition from the first position with the first pitch to the second position with the second pitch, actuation member 164 may be moved between the first position and the second position, with a plurality of intermediate positions therebetween, as the rotor 130, 132, 230 is tilted from the vertical position 200 and the horizontal position 202. As rotor 130, 132, 230 transitions from the first position to the second position, pitch change assembly 166, 266 may move actuation member 164 which, in turn, moves control plate 168.

[0091] In the example described above with respect to Figures 5 A and 5B, pitch change assembly 166 connects actuation member 164 with a mount, mounting arm 196, via drive link 194. Drive link 194 pivots about mounting arm 196, causing the actuation member 164 to move towards or away from tilt axis 182. Mounting arm 196 may be rotationally stationary relative while pylon 160 pivots about boom 140, 142. By moving the actuation member 164 towards and / or away from tilt axis 182, actuation member 164 pushes and / or pulls control plate 168 to adjust the pitch of the plurality of blades 175.

[0092] In the example described above with respect to Figures 7A and 7B, pitch change assembly 266 connects actuation member 164 with mount 294. Mount 294 may be configured as a cam or a channel with a profile to move actuation member 164 towards and / or away from tilt axis 282. Mount 294 may again be rotationally stationary relative to pylon 160 while pylon 160 pivots. By moving the actuation member 164 towards and / or away from tilt axis 282, actuation member 164 pushes and / or pulls control plate 168 to adjust the pitch of the plurality of blades 175.

[0093] In a step 306 and with reference to both examples, as control plate 168 is moved as described above, root end portion 176 of rotor blades 175 are rotated by connectors 178 to change pitch. When the actuation member 164 is moved from the first position, the pitch of rotor blades 175 is changed to the second pitch of the second position 198.

[0094] Step 308 may include rotating rotor blades 175 at the second position 198 with second pitch, which may produce a second thrust.

[0095] From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present disclosure which come within the province of those persons having ordinary skill in the art to which the aforementioned disclosure pertains. However, it is intended that all such variations not departing from the spirit of the disclosure be considered as within the scope thereof as limited by the appended claims.

Claims

CLAIMS1. A pitch control system configured to be used with an aircraft, the system comprising: a boom having an end portion; a rotor pivotally connected to the end portion of the boom, the rotor being tiltable between a first position and a second position and between a plurality of intermediate positions, the rotor having a plurality of blades, wherein the plurality of blades are configured to adjust pitch; a pitch change assembly including: a base connected to the distal end of the boom, the base being rotationally stationary; and a mount connected to the base; and an actuation member operatively connected with the mount and with the plurality of blades, the actuation member configured to move relative to the mount in a first direction and in a second direction, the actuation member being configured to move with the rotor when the rotor tilts such that, as the rotor transitions between the first position and the second position, the pitch of the plurality of blades is adjusted by the actuation member moving relative to the mount.

2. The pitch control system of claim 1, wherein the mount connects with the actuation member through a link, wherein the link is pivotally coupled to the mount and to the actuation member.

3. The pitch control system of claim 2, wherein the mount defines a drive axis about which the link rotates.

4. The pitch control system of claim 3, wherein the rotor tilts about a tilt axis, the tilt axis defining a tilt path of the rotor when the rotor is tilted.

5. The pitch control system of claim 4, wherein a length of the link defines a link path that is spaced away from the drive axis, wherein a distance between the tilt path and the link path changes based on a position of the link.

6. The pitch control system of claim 5, wherein the pitch of the plurality of blades changes based on the distance between the tilt path and the link path.

7. The pitch control system of claim 6, wherein the plurality of blades have a first pitch when the distance has a first magnitude, and a second pitch when the distance has a second magnitude.

8. The pitch control system of claim 1, wherein the movement of the actuation member changes the pitch of the plurality of blades collectively.

9. The pitch control system of claim 8, wherein the actuation member causes the collective pitch of the plurality of blades to increase for a period of time and to decrease for a period of time as the rotor tilts between the plurality of intermediate positions.

10. A pitch control system configured to be used with a tiltrotor aircraft, the pitch control system operatively connected with a plurality of blades and configured to adjust the pitch of the plurality of blades, the pitch control system comprising: a base connected to a distal end portion of a boom; a mount connected to the base and including a profile; and an actuation member operatively connected with the mount and with the plurality of blades, the actuation member configured to follow the profile of the mount and to move relative to the mount in a first direction, in a second direction, and between a first position and a second position with a plurality of intermediate positions between the first position and the second position, wherein, as the actuation member moves between the first position and the second position, the pitch of the plurality of blades is adjusted by the actuation member moving in the first direction and / or the second direction.

11. The pitch control system of claim 10, wherein the actuation member is configured to move in the first direction and in the second direction based on changes in a location of the actuation member along the profile of the mount.

12. The pitch control system of claim 10, further including a plurality of sections that together form the profile, the plurality of sections including a first section configured to cause the actuation member to increase the pitch of the plurality of blades.

13. The pitch control system of claim 12, wherein the profile includes a second section configured to cause the actuation member to decrease the pitch of the plurality of blades.

14. The pitch control system of claim 13, wherein the profile includes a third section configured to cause the actuation member to maintain the pitch of the plurality of blades approximately constant.

15. The pitch control system of claim 13, wherein the first section causes a first rate of change to the pitch of the plurality of blades and the second section causes a second rate of change to the pitch of the plurality of blades, the second rate of change being different than the first rate of change.

16. The pitch control system of claim 10, wherein the profile of the mount is non-linear.

17. A method of controlling blade pitch, the method comprising: rotating a plurality of blades of a rotor while an actuation member is in a first position, the plurality of blades having a first pitch; moving the actuation member from the first position to a second position by tilting the rotor about a tilt axis, the actuation member tilting with the rotor; changing pitch of the plurality of blades to a second pitch as the actuation member tilts with the rotor, the actuation member being movably connected to a mount, a position of the actuation member relative to the mount causing motion of the actuation member in a first direction away from the tilt axis or in a second direction toward the tilt axis; and rotating the plurality of blades at the second pitch while the actuation member is in the second position.

18. The method of claim 17, wherein the mount is rotationally stationary as the actuation member moves between the first position and the second position.

19. The method of claim 17, wherein the mount connects with the actuation member through a link, the link pivoting with respect to the mount and the actuation member as the actuation member tilts with the rotor.

20. The method of claim 17, wherein the mount is a cam including a profile, the profile moving the actuation member in the first direction and in the second direction based on a location of the actuation member along the profile of the mount.

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