Systems, methods, and devices for changing blade pitch

Abstract

A rotor pitch control system is configured to be used with a tiltrotor aircraft. The pitch control system includes a rotor hub (170), a blade (175) supported by the rotor hub, the blade configured to rotate about the rotor hub in order to adjust a pitch of the blade, a control plate (168) connected with the blade, a shaft (162) connected with the rotor hub, the shaft configured to rotate, spinning the hub, the control plate, and the blade, and an actuation rod (164) operatively connected with the control plate, the actuation rod having a first position and a second position. The actuation rod, when in the first position, places the blade at a first pitch by rotating a portion of the blade that is supported with the rotor hub, and the actuation rod, when in the second position, places the blade at a second pitch.

Description

SYSTEMS, METHODS, AND DEVICES FOR CHANGING BLADE PITCHCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 634,732, 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 provides for a rotor pitch control system configured to be used with a tiltrotor aircraft. The pitch control system may include a rotor hub, a blade supported by the rotor hub, the blade configured to rotate about the rotor hub in order to adjust a pitch of the blade, a control plate connected with the blade, a shaft connected with the rotor hub, the shaft configured to rotate, spinning the hub, the control plate, and the blade, and anactuation rod operatively connected with the control plate, the actuation rod having a first position and a second position. The actuation rod may, when in the first position, place the blade at a first pitch by rotating a portion of the blade that is supported with the rotor hub, and the actuation rod, when in the second position, may place the blade at a second pitch.

[0007] The present disclosure additionally provides for a pitch control system configured to be used with an aircraft with at least one rotor movable between a rotorborne position and a wingborne position. The system may include a hub, a plurality of blades supported by the hub, each of the plurality of blades configured to rotate to adjust pitch, and a control plate connected with the plurality of blades. The system may also include an actuation rod operatively connected with the control plate. The actuation rod, when the at least one rotor is in the rotorborne position, may move the control plate to place the plurality of blades at a first pitch, and the actuation rod, when the at least one rotor is in the wingborne position, may move the control plate to place the plurality of blades at a second pitch.

[0008] The present disclosure further includes a method of controlling blade pitch, the method including rotating a plurality of blades that each have a first pitch while an actuation member is in a first position, and moving the actuation member from the first position to a second position. The method may further include changing the pitch of the plurality of blades to each have a second pitch via the movement of the actuation member, and rotating the plurality of blades at the second pitch, while the actuation member does not rotate with the plurality of blades.BRIEF 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, eachof 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 tilt rotors in the vertical position according to the present disclosure.

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

[0016] FIG. 4 is a top down view of one example of the pitch control system, according to the present disclosure.

[0017] FIGS. 5 A and 5B respectively illustrate a first position of the pitch control system and a second position of the pitch control system.

[0018] FIG. 6 illustrates a flow chart corresponding to a method of controlling blade pitch.

[0019] 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.

[0020] 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 theart 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

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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 tilt rotors 130, 132, and booms 142 support tilt rotors 230. For example, in Figure 1A, 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.

[0027] 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 tilt 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 wingbome configuration 152.

[0028] 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, tilt-capable 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. Insome 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 1 A-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.

[0029] 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.

[0030] 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, actuators 166, 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 bediscontinuous, 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.

[0031] 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).

[0032] 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 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.

[0033] 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.

[0034] 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.

[0035] 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 rotorborne configuration 150, control surfaces, along with a landing gear (not shown) may be extended and / or engaged.

[0036] 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.

[0037] Aircraft 102 may operate at a transitional speed. The transitional speed may be considered a “medium” speed and correspond to aircraft 102 transitioning between rotorborne 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.

[0038] 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. Multiplecomponents 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.

[0039] 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 one or more actuators 166 (Figure 3).

[0040] 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 rotorbome 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.

[0041] 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.

[0042] To assist with maneuvering aircraft 102 in rotorbome 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 rotorbome configuration 150 and wingborne configuration 152. For example, in rotorbome 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 flightcharacteristics of rotorborne configuration 150, wingbome configuration 152, and transitions between these configurations, the pitch of each rotor blade 175 may be adjusted.

[0043] With reference to Figure 3, a 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). Pitch control system 156 may be operatively connected with motor 158 on pylon 160.

[0044] 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 wingborne configuration 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.

[0045] 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.

[0046] 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 rotor hub base 184 with an inner blade support 186 and an outer blade support 188 (Figures 5 A and 5B). Each rotor blade 175 may include a root end portion 176 retained within rotor hub 170.

[0047] Rotor hub 170 may support one or more rotor blades 175. In some examples, rotor hub 170 may support two, three, four, five, or more, rotor blades 175. In some examples, as shown in Figure 4, rotor hub 170 supports four rotor blades.

[0048] Inner blade support 186 and outer blade support 188 may be configured to support each root end portion 176 of rotor blades 175. As shown in Figure 4, inner blade support 186 and outer blade support 188 may be concentric rings that both support each blade 175. Inner blade support 186 and outer blade support 188 may extend from a base of rotor hub 170.

[0049] In some examples, inner blade support 186 and outer blade support 188 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 186 and outer blade support 188. For example, bearing 173 may be located in inner blade support 186, and bearing 174 may be located in outer blade support 188. In some examples, whenbearings 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.

[0050] 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 second type of bearing. In other examples, both bearing 173 and bearing 174 are the same type of bearing.

[0051] 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 rotorbome configuration 150 and wingborne configuration 152. In other examples, control plate 168 may change pitch of rotor blades 175 independent of the configuration of aircraft 102.

[0052] As shown in Figure 3, control plate 168 may be configured to move in a first direction and a second direction, as indicated by arrow 148, 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.

[0053] With reference to Figures 5A and 5B, control plate 168 may include a base 182 and a plurality of links 180. Links 180 may extend downward from base 182, which forms a top surface of plate 168. Links 180 may be configured to connect with connectors 178 (also referred to as pitch horns).

[0054] With reference to Figure 4, 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 link 180. 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 190, a first joint 192, and a second joint 194. The first joint 192 may connect with control plate 168 while the second joint 194 connects with root end portion 176. Connector 178 may be made of steel, alloy, composite, the like, or a combination thereof.

[0055] Each arm 190 may have a profile that assists in transferring movement from control plate 168 to rotor blades 175. For example, arm 190 may be straight, bent, tortuous, or have another type of shape to connect control plate 168 with blade 175. In the example shown in Figures 5 A and 5B, arm 190 may have a bent profile corresponding to the shape of control plate 168, providing space savings and a simplified design. In some examples, arm 190 may position first joint 192 and second joint 194 on the same horizontal plane (e.g., at the same height). In other examples, arm 190 may position first joint 192 and second joint 194 on separate horizontal planes (e.g., at different heights). First joint 192 may be pivotally connected to link 180 of control plate 168 to accommodate vertical movement of control plate 168. First joint 192 may be a spherical joint. When first joint 192 is a spherical joint, each arm 190 of each connector 178 is capable of moving with one or more degrees of freedom relative to control plate 168, as control plate 168 moves between positions.

[0056] In some examples, second joint 194 fixes root end portion 176 and connector 178 together such that end portion 176 and connector 178 do not move axially but do rotate together to adjust the pitch of blade 175. Joint 194 may key root end portion 176 to connector 178. 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 along directions that correspond to arrow 148, also moving control plate 168 in this direction to adjust the pitch of each rotor blade 175. Actuation member 164 may be connected with an actuator 166 to move towards and away from rotor hub 170.

[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] Bearing 172 allows for rotation of control plate 168 with respect to actuation member 164. In particular, bearing 172 decouples rotation of rotor hub 170 and blades 175from control plate 168. For example, this rotation of plate 168 relative to member 164 occurs when control plate 168 translates along either direction indicated with arrow 148 in Figure 3. When control plate 168 moves in the upward direction of Figure 3, this motion may cause a rotational adjustment of control plate 168, as plate 168 also moves from the position illustrated in Figure 5A to the position illustrated in Figure 5B. The positions of Figure 5A and Figure 5B are described below. Due to the rotational adjustment, bearing 172 allows control plate 168 to advance or fall behind (retard) slightly, in a direction of rotation, with respect to rotor hub 170 and blades 175.

[0061] Figures 5 A and 5B illustrate one example of pitch control system 156 transitioning rotor blades 175 between a first position 196 with a first pitch and a second position 198 with a second pitch. Figure 5 A illustrates actuation member 164 at a first position. In some examples, the pitch of rotor blades 175 are positioned in rotorbome configuration 150 to generate vertical thrust (Figure 5A). Similarly, the pitch of rotor blades 175 is changed when tilt rotors 130, 132, 230 are in wingborne configuration 152 to produce horizontal thrust to move aircraft 102 at a high rate of speed (Figure 5B).

[0062] In Figure 5A control plate 168 is at a first position 196 with connectors 178 at a generally planar position. As can be seen in Figure 5 A, control plate 168 is at a first distance DI from rotor hub 170. Figure 5B 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 5A and 5B, by moving control plate 168 from first position 196 to second position 198, control plate 168 rotates connectors 178 to rotate root end portions 176 of rotor blades 175, adjusting the pitch angle of rotor blades 175. Similarly, moving from wingborne configuration 152 to rotorborne configuration 150 may move control plate 168 towards rotor hub 170 such that connectors 178 rotate root end portions 176 of blade 175 in an opposite direction.

[0063] Figure 6 illustrates one example of a method 200 of adjusting the pitch of tilt- capable rotors 130, 132, 230. At a step 202, rotors 130, 132, 230 may rotate rotor blades 175 at a first position 196 with a first pitch, which, when rotated, produces a first thrust. This maybe a thrust useful for takeoff, as an example.

[0064] At a step 204, actuation member 164 (e.g., an actuation rod) may be moved from the first position 196, through a plurality of intermediate positions, and to the second position 198. This may occur while the rotor 130, 132, 230 is being pivoted from the vertical position to the horizontal position, or at other times during flight. Step 204 may include usingactuator 166 to move actuation member 164, resulting in similar movement of control plate 168.

[0065] In a step 206, as control plate 168 is moved, root end portion 176 of rotor blades 175 are rotated by connectors 178 to change blade pitch. A step 208 may include rotating rotor blades 175 at the second position 198 with second pitch, which may produce a second thrust that is different from the first thrust.

[0066] 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 rotor pitch control system configured to be used with a tiltrotor aircraft, the pitch control system comprising: a rotor hub; a blade supported by the rotor hub, the blade configured to rotate to adjust a pitch of the blade; a control plate connected with the blade; a shaft connected with the rotor hub, the shaft configured to rotate, spinning the rotor hub, the control plate, and the blade; and an actuation rod operatively connected with the control plate, the actuation rod having a first position and a second position; wherein the actuation rod, when in the first position, places the blade at a first pitch by rotating a portion of the blade that is supported with the rotor hub, and the actuation rod, when in the second position, places the blade at a second pitch.

2. The rotor pitch control system of claim 1, wherein the control plate moves from a first distance at a first position of the control plate to a second distance at a second position of the control plate, wherein the first distance and the second distance are measured from the rotor hub to the control plate.

3. The rotor pitch control system of claim 1, further including a connector, the connector connecting the control plate to the blade.

4. The rotor pitch control system of claim 3, wherein the connector is movably coupled to the control plate, and fixedly coupled to the blade.

5. The rotor pitch control system of claim 3, wherein the connector includes a spherical joint, the spherical joint connecting the connector with the control plate.

6. The rotor pitch control system of claim 5, wherein the control plate moves linearly and the connector and blade rotate to change the pitch of the blade.

7. The rotor pitch control system of claim 1, wherein the actuation rod is rotationally stationary relative to the shaft.

8. The rotor pitch control system of claim 7, wherein the control plate includes a bearing, the bearing having a portion configured to rotate about the actuation rod.

9. The rotor pitch control system of claim 1, wherein the rotor hub includes one or more journal bearings configured to receive the blade.

10. The rotor pitch control system of claim 1, wherein the shaft is hollow.

11. The rotor pitch control system of claim 10, wherein the actuation rod is disposed within the hollow shaft.

12. A pitch control system configured to be used with an aircraft with at least one rotor movable between a rotorborne position and a wingborne position, the pitch control system comprising: a hub; a plurality of blades supported by the hub, each of the plurality of blades configured to rotate to adjust pitch; a control plate connected with the plurality of blades; and an actuation rod operatively connected with the control plate, wherein the actuation rod, when the at least one rotor is in the rotorborne position, moves the control plate to place the plurality of blades at a first pitch, and the actuation rod, when the at least one rotor is in the wingborne position, moves the control plate to place the plurality of blades at a second pitch.

13. The pitch control system of claim 12, wherein the control plate moves from a first position at a first distance relative to the hub to a second position at a second distance from the hub, wherein changing between the first distance and the second distance causes the plurality of blades to change pitch.

14. The pitch control system of claim 12, further including a shaft connected with a motor and with the hub, the shaft being configured to rotate, spinning the hub, the control plate, and the blade while the actuation rod does not rotate with the shaft.

15. The pitch control system of claim 14, further including a plurality of connectors, each of the plurality of connectors connected with one of the plurality of blades and with the control plate, wherein the control plate includes a plurality of link members that are connected to the plurality of connectors.

16. The pitch control system of claim 15, wherein the plurality of connectors each follow a generally arc-shaped path from a respective blade to a respective one of the link members.

17. A method of controlling blade pitch comprising: rotating a plurality of blades that each have a first pitch while an actuation member is in a first position; moving the actuation member from the first position to a second position; changing the pitch of the plurality of blades to each have a second pitch via the movement of the actuation member; and rotating the plurality of blades at the second pitch while the actuation member does not rotate with the plurality of blades.

18. The method of claim 17, wherein blades are connected with a rotor hub and a control plate, the control plate is movable relative to the rotor hub.

19. The method of claim 18, wherein the control plate rotates blades between the first pitch and the second pitch as the control plate is moved relative to the rotor hub.

20. The method of claim 19, further comprising moving the control plate with the actuation member relative to the rotor hub from a first distance where each blade is at the first pitch, to a second distance relative to the rotor hub where each blade is at the second pitch.

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