rotary actuator

Abstract

A rotary actuator includes a manifold block and a rotor assembly including a rotor shaft and a plurality of arcuate pistons attached to the rotor shaft, each arcuate piston curved at a set radial distance from the rotor shaft and each piston attached to the rotor shaft via a crank arm. A pressure chamber assembly coupled to the manifold block defines a plurality of piston pressure chambers receiving and at least partially surrounding each arcuate piston, including a plurality of gland seals disposed adjacent an inlet of each piston pressure chamber to create a seal between an inner surface of the pressure chamber and an outer surface of the arcuate piston. Each gland seal includes an inner seal engaging a piston surface of the arcuate piston and a plurality of outer seals engaging an inner surface of the piston pressure chamber, thereby forming a hydraulic seal.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to rotary actuators. More particularly, the present disclosure relates to rotary actuators for controllably positioning flight control surfaces of an aircraft. BACKGROUND

[0002] Aircraft in flight are controlled by manipulating the aircraft's flight control surfaces, including primary flight control surfaces such as ailerons, elevators, and rudders, as well as secondary flight control surfaces such as spoilers, flaps, slats, air brakes, and the like. Actuation of the flight control surfaces enables the pilot to control the pitch, yaw, roll, and lift of the aircraft, among other flight characteristics.

[0003] Movement of the flight control surfaces is typically achieved via one or more linear actuators, which are typically positioned generally perpendicular to the pivot axis of the coupled control surface, and connected to the control surface by a hinged link. This positioning often requires the linear actuator to be installed within the rudder, elevator, or wing.

[0004] In pursuit of higher efficiency and enhanced flight performance, aircraft wings have become increasingly thin over time. In particular, the distance between the top and bottom of the outer mold line (OML) at the typical control surface pivot axis has become significantly smaller. When a conventional piston-like linear actuator is installed within such thin wings, the actuator or hinged link can partially protrude beyond the surface of the wing, increasing drag and reducing fuel efficiency, even when surrounded by a round cap or bubble cap.

[0005] In particular, ailerons are positioned along the trailing edge of the wing, where only minimal internal space is available for the coupled actuator. Therefore, for such applications, it is desirable to use a rotary hydraulic actuator that takes up less real estate. Unfortunately, prior rotary hydraulic actuators are not able to operate consistently without hydraulic leaks, which can affect the precise positioning of the associated aileron and create numerous maintenance issues. SUMMARY

[0006] The present disclosure provides rotary actuators, control surface actuator systems including rotary actuators, and methods of actuating aircraft control surfaces using rotary actuators.

[0007] In some examples, the present disclosure relates to a rotary actuator including a manifold block and a first rotor assembly mounted to the manifold block. The first rotor assembly in turn includes a first rotor shaft extending into the manifold block; and a plurality of arcuate pistons attached to the rotor shaft, each arcuate piston curved at a set radial distance from an axis of rotation of the rotor shaft, and each piston attached to the rotor shaft via a crank arm; a first pressure chamber assembly coupled to the manifold block, the first pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose each arcuate piston; and a plurality of gland seals disposed adjacent an inlet of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and an outer surface of the arcuate piston inserted therein, wherein each gland seal includes an inner seal configured to engage a surface of the arcuate piston and a plurality of outer seals configured to engage an inner surface of the piston pressure chamber such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein. The first rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers causes the arcuate pistons disposed within each piston pressure chamber to translate at the set radial distance about the axis of rotation of the first rotor shaft and thereby rotate the first rotor shaft.

[0008] In some examples, the present disclosure relates to a control surface actuator system including a control surface of an aircraft, a rotary actuator coupled to the control surface such that operation of the rotary actuator actuates movement of the control surface. The rotary actuator can include a manifold block and first and second rotor assemblies mounted to opposite sides of the manifold block along a rotation axis. Each of the first and second rotor assemblies in turn includes a rotor shaft extending into the manifold block along the rotation axis; a plurality of arcuate pistons attached to the rotor shaft, each piston curved along a defined radial distance from the rotation axis of the rotor shaft and each piston attached to the rotor shaft via an intermediate crank arm; a pressure chamber assembly coupled to the manifold block, the pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose the plurality of arcuate pistons; and a plurality of gland seals disposed adjacent an inlet of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and the arcuate piston disposed therein. Each gland seal includes an inner seal configured to engage the arcuate piston and a plurality of outer seals configured to engage an inner surface of the piston pressure chamber such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein. Each rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers causes the arcuate pistons disposed within each piston pressure chamber to translate about the rotation axis, thereby increasing a volume of the piston pressure chamber and thereby rotating the coupled rotor shaft.

[0009] In some examples, the present disclosure relates to a method of actuating an aircraft control surface. The method can include providing a rotary actuator, where the rotary actuator includes a manifold block and a first rotor assembly mounted to the manifold block. The first rotor assembly can include a first rotor shaft extending into the manifold block; a plurality of arcuate pistons attached to the rotor shaft, each piston curved along a defined radial distance from an axis of rotation of the rotor shaft, and each piston attached to the rotor shaft via an intermediate crank arm; a first pressure chamber assembly coupled to the manifold block, the first pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose the plurality of arcuate pistons; where the manifold block defines a plurality of internal passages to deliver hydraulic fluid to the piston pressure chambers; and a plurality of gland seals disposed proximate an entrance of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and the arcuate piston disposed therein. Each gland seal can include an inner seal configured to engage a surface of the arcuate piston and a plurality of outer seals configured to engage the inner surface of the piston pressure chamber, such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein. The first rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers via the plurality of internal passages of the manifold block causes the arcuate pistons disposed within each piston pressure chamber to translate about the axis of rotation of the first rotor shaft, thereby rotating the first rotor shaft. An inner end of the first rotor shaft extends into a recess formed in the manifold block, where an output lug couples the inner end of the first rotor shaft to the aircraft control surface. The method can further include delivering pressurized hydraulic fluid to the first pressure chamber assembly via the internal passages of the manifold block to increase a hydraulic fluid pressure within the piston pressure chambers of the first pressure chamber assembly; rotating the first rotor shaft by pushing the arcuate pistons disposed within the piston pressure chambers of the first pressure chamber assembly to translate about the axis of rotation of the first rotor shaft due to the increase in hydraulic fluid pressure within the piston pressure chambers; moving the output lug coupled to the inner end of the first rotor shaft by rotating the first rotor shaft; and actuating the aircraft control surface by moving the output lug.

[0010] The features, functions, and advantages can be independently utilized or in various combinations, in various examples of the present disclosure, further details of which can be understood with reference to the descriptions and drawings below. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a schematic illustration of an aircraft identifying a selected control surface of the aircraft.

[0012] FIG. 2 is a schematic cross-sectional view illustrating a conventional linear actuator coupled to a control surface at a trailing edge of a wing.

[0013] Figure 3 depicts an exemplary rotary actuator according to the present disclosure.

[0014] Figure 4 depictsFigure 3 Exemplary rotary actuator of

[0015] Figure 5 is Figure 3 Cross-sectional view of a manifold block of a rotary actuator of

[0016] Figure 6 Depicts Figure 3 Rotor shaft, crank arm, and arcuate piston of a first rotor assembly of an exemplary rotary actuator of

[0017] Figure 7 Depicts Figure 3 Pressure chamber assembly of a first rotor assembly of an exemplary rotary actuator of

[0018] Figure 8 Depicts Figure 3 Cross-sectional view of a first rotor assembly of a rotary actuator of

[0019] Figure 9 Depicts Figure 3 Cross-sectional view of a piston pressure chamber of a first rotor assembly of a rotary actuator of

[0020] Figure 10 is Figure 3 Cross-sectional view of a gland seal of a piston pressure chamber of a rotary actuator of

[0021] Figure 11 Depicts Figure 3 Manifold block of a rotary actuator of

[0022] Figure 12 Depicts Figure 3 Rotary actuator of including first and second rotary assemblies, omitting first and second actuator housings of

[0023] Figure 13 is a schematic cross-sectional view showing a control surface actuator system including a rotary actuator of the present disclosure coupled to a control surface at a trailing edge of a wing.

[0024] Figure 14 is a flowchart depicting an illustrative method of actuating an aircraft control surface in accordance with the present disclosure. DETAILED DESCRIPTION

[0025] Various aspects and examples of a rotary actuator, a control surface actuation system, and a method of actuating an aircraft control surface will be described hereinafter and shown in the accompanying drawings, which are meant to be exemplary and illustrative, and not necessarily definitive. Unless otherwise indicated, the rotary actuator, system, and method, various steps and variations thereof, can but need not contain at least one of the structures, components, functions, and / or variations described, shown, and / or incorporated herein. Moreover, unless expressly excluded, processing steps, structures, components, functions, and / or variations described, shown, and / or incorporated herein can be included in other similar devices and methods, including in examples disclosed herein. The following description of various examples is merely illustrative in nature and is in no way intended to limit the examples, their application, or uses. Additionally, the advantages described herein provide are illustrative in nature and not all examples provide the same advantages or the same degree of advantages.

[0026] This DETAILED DESCRIPTION includes the following sections, in the following order: (1) Definitions; (2) Overview; (3) Examples, Components, and Alternatives; (4) Illustrative Combinations and Additional Examples; (5) Advantages, Features, and Benefits; and (6) Conclusion.

[0027] Definitions

[0028] The following definitions apply herein, unless otherwise indicated.

[0029] “Substantially” means primarily in line with the particular dimension, range, shape, concept, or other aspect that the term modifies, such that the feature or component need not be perfect, only suitable for its intended purpose or function. For example, an object that is “substantially cylindrical” means that the object resembles a cylinder, but can have one or more deviations from a true cylinder.

[0030] “Include,” “includes,” and “including” are interchangeable with “comprise,” “comprises,” and “comprising” and are meant to be open-ended terms that do not exclude additional unrecited elements or method steps.

[0031] Terms such as “first,” “second,” and “third” are used to differentiate or identify various members in a set, in the order in which they are introduced in a particular context, and are not intended to show sequential or numerical limitations, or to be fixed identifiers of the set members.

[0032] “Coupled” means a relationship wherein the performance of one object affects the performance of another, can include a direct or indirect connection through one or more intermediate components, and can be permanent or releasable, and is not necessarily limited to physical connections.

[0033] SUMMARY

[0034] Figure 1An aircraft 10 is shown in FIG. 1, including the identification of selected primary and secondary flight control surfaces of the aircraft. The aircraft flight control surfaces can include rudders 12 on vertical stabilizers 14, elevators 16 on horizontal stabilizers 18, ailerons 20 and spoilers 22 on wings 24, and slats 26 and flaps 28 also on the wings 24.

[0035] FIG. 2 is a partial cross-section of the aileron control surface 20 in combination with the wing 24, where the aileron 20 is coupled to a conventional linear actuator 30. As shown, actuation of the aileron 20 requires extension of the linear actuator 30. Due to the relatively thin cross-section of the wing 24, even in the neutral position (A), the linear actuator 30 extends beyond the envelope of the wing 24, and then further protrudes upon actuation (B). Even fully retracted, the actuator coupling 31 between the linear actuator 30 and the aileron 20 extends beyond the skin of the wing 24 (C).

[0036] An exemplary rotary actuator 32 is shown in Figure 3 and Figure 4 The rotary actuator 32 includes a manifold block 34, a first rotor assembly 36, and a second rotor assembly 38. The first and second rotor assemblies are mounted to the manifold block 34 on opposite sides of the manifold block 34, respectively. As Figure 3 Specifically shown, the manifold block 34 includes mounting brackets 40 for attaching the rotary actuator 32 within and to the aircraft 10 via the manifold block 34. The rotary actuator 32 also includes an output lug 42 that protrudes from a recess 44 formed in the manifold block 34, as Figure 4 Although the output lug 42 extends from the recess 44 in the manifold block 34, the output lug 42 is not attached to the manifold block 34, but rather is directly coupled to an inner end 45 of a first rotor shaft 46 that extends from the first rotor assembly 36, and to an inner end 47 of a second rotor shaft 48 that extends from the second rotor assembly 38, as Figure 5 The output lug 42 is also configured to be coupled to an actuator arm, which in turn is coupled to a control surface, such that operation of the rotary actuator 32 will actuate movement of the control surface.

[0037] The manifold block 34 can additionally include a hydraulic interface 50, which can include a plurality of connection ports to facilitate connection of a hydraulic system of the rotary actuator 32 to a hydraulic system of the aircraft 10.

[0038] The first and second rotor assemblies 36 and 38 can include first and second actuator housings 51 and 52, respectively. The actuator housings are sealingly coupled to the manifold block 34 on opposite sides of the manifold block, and each enclose the remaining components of the corresponding first and second rotor assemblies, as will be discussed below in particular with respect to the components of the first rotor assembly 36.

[0039] As shown in Figure 6 , the first rotor assembly 36 can include a first rotor shaft 46 that extends the length of the first rotor assembly 36 and into the manifold block 34 and defines a rotational axis 56 within the first actuator housing 51. A plurality of crank arms 58 can be attached to the first rotor shaft 46, with each crank arm coupling the first rotor shaft 46 to an arcuate piston 60. Each arcuate piston 60 is shaped to extend along a curve 61 at a set radial distance 62 from the rotational axis 56 of the first rotor shaft 46, with the set radial distance 62 of each arcuate piston 60 being the same (as shown in Figure 8 ).

[0040] Each of the arcuate pistons 60 can be configured to have an elongated cross-section with rounded edges and a rounded distal surface opposite the end of the arcuate piston 60 that is attached to the crank arm 58. The particular shape of the arcuate pistons is not critical, so long as they are precisely and smoothly machined to precise tolerances and they follow the curve 61 with the set radial distance 62. For example, the arcuate pistons 60 can have a circular cross-section (in the form of an arcuate rod), or the arcuate pistons 60 can have a square or rectangular cross-section, without departing from the scope and spirit of the present disclosure.

[0041] As shown in Figure 7 , the first rotor assembly 36 can include one or more first pressure chamber assemblies 64 coupled to and extending from the manifold block 34. Each first pressure chamber assembly 64 defines a plurality of piston pressure chambers 66, with each piston pressure chamber 66 being configured to receive and at least partially surround an arcuate piston 60, as shown in Figure 8 . The first rotor assembly 36 can be configured to include a piston pressure chamber 66 corresponding to each arcuate piston 60 in the first rotor assembly 36.

[0042] The arcuate pistons 60 and piston pressure chambers 66 can be manufactured with precise tolerances such that each arcuate piston 60 is free to move within the corresponding piston pressure chamber 66 at the set radial distance 62 from the rotational axis 56, with minimal or no contact between the outer surface 68 of the arcuate piston 60 and the inner surface 70 of the piston pressure chamber 66. Such precise tolerances can help improve the hydraulic operation of the resulting rotary actuator, in addition to eliminating destructive wear on the components of the first rotor assembly 36.

[0043] Although the arcuate pistons 60 and piston pressure chambers 66 can not make actual physical contact as the arcuate pistons 60 move within the piston pressure chambers, the piston pressure chambers are hydraulically sealed by the insertion of a gland seal assembly 72 between the outer surface 68 of the arcuate piston 60 and the inner surface 70 of the piston pressure chamber 66. The components of the gland seal 68 are shown in Figure 9 and 10shown in more detail below.

[0044] Each gland seal assembly 72 is positioned adjacent to an inlet 74 of a piston pressure chamber 66 such that, when at least partially inserted into its corresponding piston pressure chamber 66, the gland seal assembly 72 can create a hydraulic seal between the inner surface 70 of the piston pressure chamber 66 and the outer surface 68 of the arcuate piston 60. Each gland seal assembly 72 can include a gland 76 that is positioned within a gland bore 78 formed in the inner surface 70 of the piston pressure chamber 66. The gland bore 78 is typically formed around the circumference of the inner surface 70 such that, when the gland seal assembly 72 is positioned in the gland bore 78, the gland seal assembly 72 surrounds the arcuate piston 60 when the piston 60 is at least partially inserted into the piston pressure chamber 66.

[0045] The gland 76 can be retained within the gland bore 78 by the presence of a shear line 80 disposed between the inner wall 82 of the gland bore 78 and the gland 76. When sandwiched therebetween, the shear line 80 simultaneously rests in a complementary groove 84 formed in the inner wall 82 and a complementary groove 86 formed in the gland 76, as shown in Figure 10 As such, even with repeated reciprocation of the arcuate piston 60 into and out of the piston pressure chamber 66, the interaction of the shear line 80 with the grooves 84 and 86 ensures that the gland 76 is securely maintained in place.

[0046] While the gland 76 can help facilitate the necessary hydraulic seal between the pressure chamber inner surface 70 and the piston outer surface 68, each gland seal can additionally include one or more additional inner gland seals 88 that are configured to engage the surface 68 of the arcuate piston 60 and create a seal between the arcuate piston 60 and the gland 76. The inner gland seals 88 are typically rod seals. The gland 76 can additionally include a plurality of outer gland seals 90 that are positioned to engage the inner surface 82 of the gland bore 78 and are configured to create a seal between the inner surface 82 and the gland 76. The outer gland seals 90 can include a plurality of O-ring seals. The structure of the gland seal assembly 72 and its numerous sealing elements provide a secure hydraulic seal that is not only sufficient to hydraulically operate the rotary actuator 32, but also prevents hydraulic fluid leakage even after repeated operation of the rotary actuator, at least in part, due to previously unsuitable leakage of the rotary actuator mechanism. The design of the gland seal assembly 72 further allows for increased additional float of the gland assembly relative to the gland bore 78 of the pressure chamber assembly 64 and, thus, the rotary actuator is better able to accommodate dimensional variances that fall within manufacturing tolerances.

[0047] Figure 11A manifold block 34 is depicted, which is shown as translucent in order to show a plurality of internal passages 92 within the manifold block 34. The internal passages 92 are configured to deliver hydraulic fluid to at least each of the piston pressure chambers formed by the pressure chamber assemblies 64. Typically, the manifold block 34 defines a first plurality of internal passages configured to deliver hydraulic fluid to the first piston pressure chambers, and also defines a second plurality of internal passages configured to deliver hydraulic fluid to the second piston pressure chambers, such that, by delivering hydraulic fluid to the first and second piston pressure chambers in sequence, the first rotor shaft can be rotated and counter-rotated.

[0048] As mentioned above, the first rotor assembly 36 includes a first actuator housing 51, a first rotor shaft 46, and a plurality of crank arms 58 coupling the first rotor shaft 46 to a plurality of arcuate pistons 60. The plurality of arcuate pistons 60 coupled to the first rotor shaft 46 can include a first set 94 of the plurality of arcuate pistons 60 extending in a first rotational direction about the rotational axis 56; and a second set 96 of the plurality of arcuate pistons 60 extending in a second, opposite rotational direction about the rotational axis 56. Typically, the first set 94 and the second set 96 of arcuate pistons are equal in number. Thus, the rotary actuator 32 can be operated by delivering hydraulic fluid to a set of first piston pressure chambers corresponding to the arcuate pistons of the first half 94 to increase the hydraulic pressure in the piston pressure chambers, thereby causing each of the arcuate pistons 60 of the first half 94 to be pushed out of its corresponding piston pressure chamber, thereby causing rotation of the first rotor shaft 46 and actuation of the rotary actuator. Under the hydraulic push of the hydraulic pressure within the piston pressure chambers of the arcuate pistons 60 of the first half 94, the rotor shaft can rotate until each of the crank arms 58 of the arcuate pistons of the first half 94 encounters a corresponding rotational stop 98, at which point Figure 8 is seen.

[0049] The rotary actuator 32 can be returned to its initial configuration by reducing the hydraulic pressure applied to the arcuate pistons 60 of the first half 94, and applying hydraulic pressure to the second plurality of second piston pressure chambers for the arcuate pistons 60 of the second half 96, thereby counter-rotating the first rotor shaft 46 until the crank arms 58 of the arcuate pistons of the second half 96 again encounter their corresponding rotational stops 98, and the actuator 32 returns to its initial configuration.

[0050] As noted above, actuation of the rotary actuator 32 can be primarily achieved by alternating pressurization and depressurization of the first and second pluralities of piston pressure chambers. However, because the first actuator housing 51 can be sealingly coupled to the manifold block 34 and the actuator housing 51 completely encloses the first pressure chamber assembly 64, an additional internal volume is created that is defined by an outer surface 100 of the first pressure chamber assembly 64, an outer surface 102 of the first rotor shaft 46, and an inner surface 104 of the first actuator housing 51. This internal volume is referred to as a first backflow pressure volume 106.

[0051] The plurality of arcuate pistons 60 coupled to the first rotor shaft 46 can be coupled to the first rotor shaft 46 in pairs. More specifically, the plurality of arcuate pistons 60 can be coupled to the first rotor shaft 46 in an arrangement that exhibits double rotational symmetry with respect to the rotational axis 56. That is, the arrangement of arcuate pistons around the first rotor shaft can be symmetrical with respect to the first rotor shaft 46 about a rotation of 180 degrees around the rotational axis 56. This double rotational symmetry can be seen, for example, in Figure 6 , 7 and 12.

[0052] As noted above, the rotary actuator 32 can include a first rotor assembly 36 and a second rotor assembly 38, each coupled to opposite sides of the manifold block 34. Generally, the composition and configuration of the second rotor assembly 38 is selected to be substantially identical to that of the first rotor assembly 36 and symmetrical thereto via a rotation of 180 degrees about a vertical axis of symmetry 108 that is orthogonal to the rotational axis 56, as Figure 12 depicted in FIG. 12, which depicts the rotary actuator 32 with the first actuator housing 51 and the second actuator housing 52 removed. Because the second rotor assembly 38 is symmetrical to the first rotor assembly 36, the second rotor assembly 38 also includes a rotor shaft that extends at one end into the groove 44 formed in the manifold block 34 such that the output lugs 42 are coupled to the inner ends 45 and 47 of the first and second rotor shafts 46 and 48, respectively.

[0053] As exemplified by the rotary actuator 32 of Figure 12 , each of the first and second rotor assemblies 36 and 38 can include eight arcuate pistons 60 attached to each of the first and second rotor shafts 46 and 48, respectively. Further, the eight arcuate pistons 60 attached to each rotor shaft can include a first set of four arcuate pistons 60 extending in a first rotational direction about the rotational axis 56 and a second set of four arcuate pistons 60 extending in a second and opposite rotational direction about the rotational axis 56. The eight arcuate pistons 60 are additionally arranged in a manner that exhibits double rotational symmetry with respect to the rotational axis 56.

[0054] Because the volume of the rotary actuator 32 can be significantly smaller than a corresponding conventional linear actuator, the rotary actuator 32 can be advantageously incorporated into a control surface actuator system 110 as shown in Figure 13 where the rotary actuator 32 can be coupled to a control surface 114 of the aircraft 10. The control surface actuator system 110 can be configured such that operation of the rotary actuator 32 actuates movement of the control surface 114. Alternatively, or in addition, the rotary actuator 32 can be coupled to the control surface 114 via an intermediate actuator arm.

[0055] In contrast to the actuator system of FIG. 2, the rotary actuator 32 of the control system 110 can be entirely enclosed within the wing 24 having a very thin cross section as shown in Figure 13 Accordingly, the control system 110 is well suited for control systems of wing control surfaces because the disclosed rotary actuator can be entirely installed within the interior space of the associated wing structure.

[0056] The various components of the rotary actuator disclosed herein can be made of any suitable material having the necessary physical properties, and in particular, any suitable material that has been applied to the manufacture of aircraft components. In particular, the arcuate piston of the disclosed rotary actuator can be made of a stainless steel alloy meeting the AMS 5659 specification, such as 15-5PH stainless steel. The surface of the arcuate piston can be further hardened by a high velocity oxygen fuel (HVOF) coating including, for example, tungsten carbide cobalt. The gland of the gland seal can be made of an aluminum nickel bronze alloy meeting the AMS 4640 specification.

[0057] The presently disclosed rotary actuator can be manufactured by any suitable machining method capable of providing the precision tolerances required of a hydraulic system, such as CNC machining. Alternatively, or in addition, because the pressure chamber assembly in particular requires precision tolerances along the extended arcuate piston path, it can be advantageous to employ an additive manufacturing method (i.e., 3D printing) to manufacture some or all of the components of the disclosed rotary actuator.

[0058] The rotary actuator of the present disclosure can be used in a method for actuating an aircraft control surface, where the reduced size, enhanced performance, and increased durability of the presently disclosed rotary actuator can improve aircraft control surface actuation.

[0059] This section describes steps of an illustrative method for actuating an aircraft control surface as shown in the flowchart 120 of Figure 14 As appropriate, reference can be made to components and systems that can be used to perform each step. These references are for illustration only and are not intended to limit the possible ways in which any particular step of the method can be performed.

[0060] Furthermore, based on the present disclosure, it should be appreciated that additional steps can be performed without departing from the spirit of the present disclosure or the claims herein. Although the following steps are described and depicted in a particular order, such steps do not necessarily have to be performed in that order and in some cases can be performed simultaneously or in a different order than shown in the respective flowcharts. Figure 14 While the individual steps of flowchart 120 are depicted, such steps do not necessarily have to be performed in their entirety and in some cases can be performed simultaneously or in a different order than shown in the respective flowcharts.

[0061] The illustrative method of flowchart 120 can include providing a rotary actuator 32, as set forth in step 122 of flowchart 120 and as described above. The method can further include delivering pressurized hydraulic fluid to the first pressure chamber assembly 64 via the internal passage 92 of the manifold block 34 to increase the hydraulic fluid pressure within the piston pressure chamber 66 of the first pressure chamber assembly 64, as set forth in step 124 of flowchart 120. The method can further include rotating the first rotor shaft 46 by pushing the arcuate pistons 66 disposed within the piston pressure chamber 66 of the first pressure chamber assembly 64 to translate about the rotational axis 56 of the first rotor shaft 46 due to the increased hydraulic fluid pressure within the piston pressure chamber 66, as set forth in step 126 of flowchart 120. The method can further include moving the output lug 42 coupled to the inner end 45 of the first rotor shaft 46 by rotating the first rotor shaft, as set forth in step 128 of flowchart 120. The method can further include moving the actuator interface arm 112 by moving the output lug 42, as set forth in step 130 of flowchart 120. The method can further include actuating the aircraft control surface 114 by moving the actuator interface arm 112, as set forth in step 132 of flowchart 120.

[0062] The illustrative method of actuating an aircraft control surface can optionally further include returning the aircraft control surface to its initial configuration by delivering pressurized hydraulic fluid to the second plurality of piston pressure chambers 66 for the arcuate pistons 60 of the second half 96, thereby pushing the second set of plurality of arcuate pistons 96 to translate in an opposite direction about the rotational axis 56 of the first rotor shaft 46, as set forth in step 134 of flowchart 120. The method can optionally further include reciprocally moving the actuator arm 112 by counter-rotating the first rotor shaft 46, and moving the output lug 42 that couples the inner end 45 of the first rotor shaft 46 to the actuator arm 112, as set forth in step 136 of flowchart 120. The method can optionally further include returning the aircraft control surface 114 to its initial configuration by moving the actuator arm 114 to its initial position, as set forth in step 140 of flowchart 120.

[0063] Examples, Components, and Alternatives

[0064] A. Illustrative Combinations and Additional Examples

[0065] This section describes other aspects and features of the disclosed rotary actuators, aircraft control surface actuation systems, and methods of actuating aircraft control surfaces, which are presented in no particular order as a series of paragraphs, some or all of which can be combined in a lettered-numeric format for clarity and efficiency. Each of these paragraphs can be combined with one or more other paragraphs, and / or combined with the disclosure elsewhere in this application in any suitable manner. Some of the following paragraphs explicitly reference and further limit other paragraphs, providing but not limited to examples of some suitable combinations.

[0066] A1. A rotary actuator comprising: a manifold block; and a first rotor assembly mounted to the manifold block; wherein the first rotor assembly comprises: a first rotor shaft extending into the manifold block; a plurality of arcuate pistons attached to the first rotor shaft, each arcuate piston curved at a set radial distance from an axis of rotation of the first rotor shaft, and each piston attached to the first rotor shaft via a crank arm; a first pressure chamber assembly coupled to the manifold block, the first pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose each arcuate piston; a plurality of gland seals disposed adjacent an inlet of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and an outer surface of the arcuate piston inserted therein; wherein each gland seal comprises an inner seal configured to engage a surface of the arcuate piston and a plurality of outer seals configured to engage the inner surface of the piston pressure chamber, such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein; the first rotor assembly configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers causes the arcuate pistons disposed within each piston pressure chamber to translate about the axis of rotation of the first rotor shaft at the set radial distance, thereby rotating the first rotor shaft.

[0067] A2. The rotary actuator of paragraph A1, wherein a first set of the plurality of arcuate pistons extends around the axis of rotation in a first rotational direction, and a second set of the plurality of arcuate pistons extends around the axis of rotation in a second and opposite rotational direction, such that delivery of hydraulic fluid to the first piston pressure chambers of the first set of arcuate pistons causes rotation of the first rotor shaft, and delivery of the hydraulic fluid to the second piston pressure chambers of the second set of arcuate pistons causes counter-rotation of the first rotor shaft.

[0068] A3. The rotary actuator of paragraph A1 or A2, further comprising a first actuator housing sealingly coupled to the manifold block and enclosing the first pressure chamber assembly, such that an outer surface of the first pressure chamber assembly, an outer surface of the first rotor shaft, and an inner surface of the first actuator housing in combination define a first backflow pressure volume.

[0069] A4. The rotary actuator of any of paragraphs Al-A3, wherein an inner end of the first rotor shaft extends into a groove formed in the manifold block; further comprising an output lug coupled to the inner end of the first rotor shaft, wherein the output lug is configured to be coupled to a control surface.

[0070] A5. The rotary actuator of any of paragraphs Al-A4, wherein the plurality of arcuate pistons are coupled to the first rotor shaft in pairs in an arrangement having double rotational symmetry about the rotational axis.

[0071] A6. The rotary actuator of any of paragraphs Al-A5, wherein each gland seal is disposed within a gland bore formed in the inner surface of the corresponding piston pressure chamber.

[0072] A7. The rotary actuator of paragraph A6, wherein each gland seal comprises a gland held within the gland bore by a shear line disposed between the gland and the gland bore, the shear line engaging both the gland and the gland bore.

[0073] A8. The rotary actuator of any of paragraphs Al-A7, wherein the inner seal comprises a rod seal.

[0074] A9. The rotary actuator of any of paragraphs Al-A8, wherein the plurality of outer seals comprises a plurality of O-ring seals.

[0075] A10. The rotary actuator of any of paragraphs Al-A9, wherein the manifold block defines a plurality of inner passages configured to deliver hydraulic fluid to the piston pressure chambers.

[0076] A11. The rotary actuator of paragraph A10, wherein the manifold block defines a first plurality of inner passages configured to deliver hydraulic fluid to the first piston pressure chambers, and further defines a second plurality of inner passages configured to deliver hydraulic fluid to the second piston pressure chambers, such that the first rotor shaft can be rotated and counter-rotated by delivering hydraulic fluid to the first and second piston pressure chambers in sequence.

[0077] A12. The rotary actuator of any of paragraphs Al-A11, further comprising a second rotor assembly mounted to the manifold block on an opposite side from the first rotor assembly; wherein the second rotor assembly is substantially symmetrical about rotation about a vertical axis that is orthogonal to the rotation axis as the first rotor assembly; and an inner end of a second rotor shaft of the second rotor assembly extends into a recess formed in the manifold block; further comprising an output lug coupled to the inner ends of both the first rotor shaft and the second rotor shaft, wherein the output lug is configured to be coupled to a control surface.

[0078] A13. The rotary actuator of paragraph A12, wherein each of the first and second rotor assemblies includes eight arcuate pistons attached to its respective rotor shaft; wherein each of the first and second rotor assemblies includes a first set of four arcuate pistons extending in a first rotational direction about the rotation axis, and a second set of four arcuate pistons extending in a second and opposite direction about the rotation axis; such that delivery of hydraulic fluid to the first piston pressure chambers of the first set of four arcuate pistons for each of the first and second rotor assemblies causes rotation of the combined first and second rotor shafts, and delivery of the hydraulic fluid to the second piston pressure chambers of the second set of four arcuate pistons for each of the first and second rotor assemblies causes counter-rotation of the combined first and second rotor shafts.

[0079] B1. A control surface actuator system comprising: a control surface of an aircraft; a rotary actuator coupled to the control surface such that operation of the rotary actuator actuates movement of the control surface; wherein the rotary actuator comprises: a manifold block; and first and second rotor assemblies mounted to opposite sides of the manifold block along a rotary axis; wherein each of the first and second rotor assemblies comprises a rotor shaft extending into the manifold block along the rotary axis; a plurality of arcuate pistons attached to the rotor shaft, each piston being curved along a defined radial distance from the rotary axis of the rotor shaft, and each piston being attached to the rotor shaft via an intermediate crank arm; a pressure chamber assembly coupled to the manifold block, the pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose the plurality of arcuate pistons; a plurality of gland seals disposed adjacent an inlet of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and the arcuate piston disposed therein; wherein each gland seal comprises an inner seal configured to engage the arcuate piston and a plurality of outer seals configured to engage the inner surface of the piston pressure chamber, such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein; and each rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers causes the arcuate pistons disposed within each piston pressure chamber to translate about the rotary axis, thereby increasing piston pressure chamber volume and thereby causing the coupled rotor shaft to rotate.

[0080] B2. The control surface actuator system of paragraph B1, wherein the control surface is one of: a wing flap, an elevator, a rudder, a spoiler, a wing slat, a wing slot, an airbrake, a control horn, or a trim tab.

[0081] B3. The control surface actuator system of paragraph B1 or B2, wherein the rotary actuator is disposed entirely within an aircraft wing.

[0082] C1. A method of actuating an aircraft control surface, wherein the aircraft control surface is coupled to an actuator arm; comprising: providing a rotary actuator comprising: a manifold block; and a first rotor assembly mounted to the manifold block; wherein the first rotor assembly comprises: a first rotor shaft extending into the manifold block; a plurality of arcuate pistons attached to the rotor shaft, each piston being curved along a defined radial distance from an axis of rotation of the rotor shaft, and each piston being attached to the rotor shaft via an intermediate crank arm; a first pressure chamber assembly coupled to the manifold block, the first pressure chamber defining a plurality of piston pressure chambers configured to receive and at least partially enclose the plurality of arcuate pistons; wherein the manifold block defines a plurality of internal passages to deliver hydraulic fluid to the piston pressure chambers; a plurality of gland seals disposed proximate an entrance of each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and the arcuate piston disposed therein; wherein each gland seal comprises an inner seal configured to engage a surface of the arcuate piston and a plurality of outer seals configured to engage the inner surface of the piston pressure chamber, such that a hydraulic seal is formed between each piston pressure chamber and the arcuate piston inserted therein; wherein the first rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers via the plurality of internal passages of the manifold block causes the arcuate pistons disposed within each piston pressure chamber to translate about the axis of rotation of the first rotor shaft, thereby rotating the first rotor shaft; and an inner end of the first rotor shaft extends into a groove formed in the manifold block, wherein an output lug couples the inner end of the first rotor shaft to an end of the actuator arm, which is also coupled to the aircraft control surface; delivering pressurized hydraulic fluid to the first pressure chamber assembly via the internal passages of the manifold block to increase hydraulic fluid pressure within the piston pressure chambers of the first pressure chamber assembly; rotating the first rotor shaft by pushing the arcuate pistons disposed within the piston pressure chambers of the first pressure chamber assembly to translate about the axis of rotation of the first rotor shaft due to the increase in hydraulic fluid pressure within the piston pressure chambers; moving the output lug coupled to the inner end of the first rotor shaft by rotating the first rotor shaft; moving the actuator arm by moving the output lug; and actuating the aircraft control surface by moving the actuator arm.

[0083] C2. The method of paragraph CI, wherein a first set of the plurality of arcuate pistons extends in a first rotational direction about the rotational axis and a second set of the plurality of arcuate pistons extends in a second and opposite rotational direction about the rotational axis; and the manifold block defines a second plurality of internal passages configured to deliver hydraulic fluid to the second piston pressure chambers; the method further comprising: delivering pressurized hydraulic fluid to the second piston pressure chambers and urging the second set of the plurality of arcuate pistons to translate in opposite directions about the rotational axis of the first rotor shaft and reciprocally translate the first set of the plurality of arcuate pistons disposed within the first piston pressure chambers about the rotational axis of the first rotor shaft, thereby causing the first rotor shaft to counter-rotate; reciprocally moving the actuator arm by counter-rotating and moving the first rotor shaft to couple the inner end of the first rotor shaft to the output lug of the actuator arm; and returning the aircraft control surface to an initial configuration by moving the actuator arm to its initial position.

[0084] C3. The method of paragraph CI or C2, wherein providing the rotary actuator includes providing a second rotor assembly mounted to the manifold block on an opposite side of the first rotor assembly, the second rotor assembly being substantially mirror-symmetric to the first rotor assembly about a plane bisecting the manifold block orthogonal to the rotational axis, and an inner end of a second rotor shaft of the second rotor assembly extending into the groove formed in the manifold block, and wherein the output lug is additionally coupled to the inner end of the second rotor shaft.

[0085] C4. The method of paragraph C3, wherein providing the rotary actuator includes providing first and second rotor assemblies, each of the first and second rotor assemblies including eight arcuate pistons attached to each of the first and second rotor shafts.

[0086] C5. The method of paragraph C4, wherein providing the rotary actuator includes providing first and second rotor assemblies, each of the first and second rotor assemblies including eight arcuate pistons attached to each of the first and second rotor shafts, wherein each of the first and second rotor assemblies includes a first set of four arcuate pistons extending in a first rotational direction about the rotational axis in an arrangement having double rotational symmetry about the rotational axis, and a second set of four arcuate pistons extending in a second and opposite rotational direction about the rotational axis.

[0087] C6. The method of any of paragraphs CI to C5, wherein the aircraft control surface is a wing control surface, and providing the rotary actuator includes mounting the rotary actuator entirely within an internal volume of a wing structure.

[0088] Advantages, Features, and Benefits

[0089] The rotary actuators disclosed herein, including control surface actuator systems comprising the rotary actuators, and methods of actuating control surfaces including operation of the rotary actuators, provide significant benefits when compared to existing linear actuator designs for actuating aircraft control surfaces.

[0090] In contrast to linear actuators, which must mechanically convert the resulting linear motion into rotational motion that can be incompatible with the limitations of available operating volumes, the disclosed rotary actuators are configured to directly produce rotational motion.

[0091] As wing thickness is reduced, the volume available for control surface actuator systems including linear actuators becomes limited. At least a portion of the linear actuator can be forced to protrude outside of the wing interior, requiring a blister or fairing to enclose the protrusion and resulting in reduced aerodynamic performance. Since the rotary actuator described herein requires less operating volume, it can even be fully incorporated within even relatively thin wing structures. Additionally, since the actuator assembly can be positioned closer to the trailing edge of the wing, more volume within the wing can be used for fuel capacity.

[0092] Since the rotary actuator directly produces rotational motion, coupling to a short lever arm to provide leverage to operate the control surface is no longer required, and the control surface can be directly actuated. Furthermore, the rotary actuator has higher mechanical reliability compared to conventional toggle actuator designs sized for the same application. Toggle actuator designs require bearings sized larger than the rotary actuator in order to compensate for the non-linear loads applied by the actuator. The rotary actuator described herein produces significantly reduced bearing loads, resulting in less bearing wear and higher actuator reliability.

[0093] Toggle actuators must also be mounted to the spar and require structural reinforcement in order to provide sufficient stability to the actuator to withstand the loads applied to the actuator during operation. In contrast, the mounting of the rotary actuator does not require additional reinforcement, resulting in a lighter airframe. Additionally, due to its compact design, the rotary actuator is less susceptible to buckling loads.

[0094] The rotary actuator presently described is significantly improved over previous versions of the rotary actuator, as the disclosed gland seal provides reliable hydraulic operation without the common hydraulic leaks observed in existing systems, resulting in a rotary actuator that requires less maintenance and has an extended service life over previous rotary actuators.

[0095] CONCLUSION

[0096] The disclosure set forth above can encompass a variety of different examples having independent utility. While each of these has been disclosed in its (one or more) preferred form(s), the specific examples of it disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. To the extent that section headings are used, these are for organizational purposes only and are not to be construed as limiting the subject matter described. Subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various elements, features, functions and / or properties disclosed herein. The following claims particularly point out certain combinations and subcombinations that are regarded as novel and nonobvious. Other combinations and subcombinations can be claimed in applications claiming priority from this application or related applications. Such accompanying claims, whether broader, narrower, identical, or different, also are regarded as included within the subject matter of the present disclosure.

Claims

1. A rotary actuator (32) comprising: a manifold block (34); and a first rotor assembly (36) mounted to the manifold block (34); wherein the first rotor assembly (36) comprises: a first rotor shaft (46) extending into the manifold block (34); a plurality of arcuate pistons (60) attached to the rotor shaft, each arcuate piston curved at a set radial distance from an axis of rotation (56) of the first rotor shaft (46), and each piston attached to the first rotor shaft (46) via a crank arm (58); a first pressure chamber assembly (64) coupled to the manifold block (34), the first pressure chamber defining a plurality of piston pressure chambers (66), each piston pressure chamber configured to receive and at least partially enclose a corresponding arcuate piston (60); a plurality of gland seals (72) disposed adjacent an inlet (74) of each piston pressure chamber (66) and creating a seal between an inner surface (70) of the piston pressure chamber (66) and an outer surface (68) of the corresponding arcuate piston inserted therein; wherein each gland seal (72) comprises an inner seal (88) configured to engage a surface of the arcuate piston (60) and a plurality of outer seals (90) configured to engage the inner surface (70) of the piston pressure chamber (66) such that a hydraulic seal is formed between each piston pressure chamber (66) and the corresponding arcuate piston (60) inserted therein, and wherein each gland seal (72) is disposed within a gland bore (78) formed in the inner surface (70) of its corresponding piston pressure chamber (66); the first rotor assembly (36) is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers (66) causes the arcuate pistons (60) disposed within each piston pressure chamber (66) to translate about the axis of rotation (56) of the first rotor shaft (46) at the set radial distance, thereby causing the first rotor shaft (46) to rotate. the plurality of arcuate pistons (60) comprises a first set (94) of the plurality of arcuate pistons extending in a first rotational direction about the axis of rotation (56) and a second set (96) of the plurality of arcuate pistons extending in a second and opposite rotational direction about the axis of rotation (56) such that delivery of hydraulic fluid to a first plurality of piston pressure chambers (66) for the first set (94) of arcuate pistons causes rotation of the first rotor shaft (46) and delivery of the hydraulic fluid to a second plurality of second piston pressure chambers for the second set (96) of arcuate pistons causes counter-rotation of the first rotor shaft (46).

2. The rotary actuator of claim 1, wherein, ​ 3. The rotary actuator of claim 1 or 2, further comprising a first actuator housing (51) sealingly coupled to the manifold block (34) and enclosing the first pressure chamber assembly (64) such that an outer surface (100) of the first pressure chamber assembly (64), an outer surface (102) of the first rotor shaft (46), and an inner surface (104) of the first actuator housing (51) in combination define a first backflow pressure volume (106).

4. The rotary actuator of claim 1 or 2, wherein, an inner end (45) of the first rotor shaft (46) extends into a groove (44) formed in the manifold block (34); further comprising an output lug (42) coupled to the inner end (45) of the first rotor shaft (46), wherein the output lug (42) is configured to be coupled to a control surface (114).

5. The rotary actuator of claim 1 or 2, wherein, the plurality of arcuate pistons (60) are coupled to the first rotor shaft (46) in pairs in an arrangement having double rotational symmetry about the rotational axis (56).

6. The rotary actuator of claim 1 or 2, wherein, the manifold block (34) defines a plurality of internal passages (92) configured to deliver hydraulic fluid to the piston pressure chambers (66).

7. The rotary actuator of claim 2, wherein, the manifold block (34) defines a first plurality of internal passages (92) configured to deliver hydraulic fluid to the first piston pressure chambers (66) and further defines a second plurality of internal passages (92) configured to deliver hydraulic fluid to the second piston pressure chambers such that the first rotor shaft (46) can be rotated and counter-rotated by delivering hydraulic fluid to the first and second piston pressure chambers in sequence.

8. The rotary actuator of claim 2, further comprising a second rotor assembly (38) mounted to the manifold block (34) on an opposite side from the first rotor assembly (36); wherein the second rotor assembly (38) is substantially symmetrical to the first rotor assembly (36) about rotation about a vertical axis (108) that is orthogonal to the rotational axis (56); and an inner end (47) of a second rotor shaft (48) of the second rotor assembly (38) extends into a groove (44) formed in the manifold block (34); further comprising an output lug (42) coupled to the inner ends of the first rotor shaft (46) and the second rotor shaft (48), wherein the output lug (42) is configured to be coupled to a control surface (114).

9. The rotary actuator of claim 8, wherein, each of the first and second rotor assemblies includes eight arcuate pistons (60) attached to its respective rotor shaft; wherein each of the first and second rotor assemblies includes a first set (94) of four arcuate pistons extending in a first rotational direction about the rotational axis (56); and a second set (96) of four arcuate pistons extending in a second and opposite rotational direction about the rotational axis (56); such that delivery of hydraulic fluid to the first piston pressure chambers (66) of the first and second sets (94) of four arcuate pistons for each of the first and second rotor assemblies causes rotation of the combined first and second rotor shafts, and delivery of the hydraulic fluid to the second piston pressure chambers of the second sets (96) of four arcuate pistons for each of the first and second rotor assemblies causes counter-rotation of the combined first and second rotor shafts.

10. A control surface actuator system comprising: a control surface (114) of an aircraft (10); a rotary actuator (32) coupled to the control surface (114) such that operation of the rotary actuator actuates movement of the control surface (114); wherein the rotary actuator (32) comprises: a manifold block (34); and first and second rotor assemblies mounted to opposite sides of the manifold block (34) along a rotation axis (56); wherein each of the first and second rotor assemblies comprises a rotor shaft (46, 48) extending into the manifold block (34) along the rotation axis (56); a plurality of arcuate pistons (60) attached to the rotor shaft, each piston curved along a defined radial distance from the rotation axis (56) of the rotor shaft, and each piston attached to the rotor shaft via an intermediate crank arm (58); a pressure chamber assembly (64) coupled to the manifold block (34), the pressure chamber assembly (64) defining a plurality of piston pressure chambers (66) configured to receive and at least partially enclose the plurality of arcuate pistons (60); a plurality of gland seals (72) disposed adjacent an inlet (74) of each piston pressure chamber (66) and creating a seal between an inner surface (70) of the piston pressure chamber and the arcuate piston (60) disposed therein; wherein each gland seal (72) comprises an inner seal (88) configured to engage the arcuate piston (60) and a plurality of outer seals (90) configured to engage the inner surface (70) of the piston pressure chamber, such that a hydraulic seal is formed between each piston pressure chamber (66) and the arcuate piston (60) inserted therein, and wherein each gland seal (72) is disposed within a gland bore (78) formed in the inner surface (70) of its corresponding piston pressure chamber (66); and each rotor assembly is configured such that delivery of hydraulic fluid to the plurality of piston pressure chambers (66) causes the arcuate pistons (60) disposed within each piston pressure chamber to translate about the rotation axis (56), increasing piston pressure chamber volume and thereby rotating the coupled rotor shaft.

11. The control surface actuator system of claim 10, wherein, the control surface (114) is one of: a wing flap, an elevator, a rudder, a spoiler, a wing slat, a wing slot, an airbrake, a control horn, or a trim tab.

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