Rotary Actuator

Abstract

To provide a rotary actuator preventing leakage of liquid.SOLUTION: A rotary actuator includes a manifold block and a rotor assembly, and the rotor assembly includes a plurality of arcuate pistons 60. Each arcuate piston 60 curves at a set radial distance from a rotor shaft, and each piston 60 is attached to the rotor shaft via a crank arm. A pressure chamber assembly 64 coupled to the manifold block receives each arcuate piston 60, defines a plurality of piston pressure chambers, and includes a plurality of gland seals 72 disposed adjacent to an entrance 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 60. Each gland seal 72 includes an inner seal 88 that engages with the piston surface of the arcuate piston 60 and a plurality of outer seals 90 that engage with the inner surface of the piston pressure chamber, and forms a hydraulic seal.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to rotary actuators, and more particularly to rotary actuators used to controllably position flight control surfaces of an aircraft. [Background technology]

[0002] Introduction An aircraft in flight is controlled by manipulation of the aircraft's flight control surfaces, which include primary flight control surfaces such as ailerons, elevators, and rudder, and secondary flight control surfaces such as spoilers, flaps, slats, and air brakes. Actuation of the flight control surfaces allows the pilot to control the pitch, yaw, roll, and lift of the aircraft, among other flight characteristics.

[0003] Movement of flight control surfaces is typically effected via one or more linear actuators, generally positioned approximately perpendicular to the pivot axis of the associated control surface and connected to the control surface by an articulated linkage. This arrangement often requires that the linear actuators be located within the rudder, elevator, or wing.

[0004] In the pursuit of greater efficiency and enhanced flight performance, aircraft wings have become thinner over time. In particular, the distance between the top and bottom of the outer mold line (OML) at a typical control surface pivot point has been significantly reduced. When a conventional piston-type linear actuator is installed within such a thin wing, the actuator or articulation linkage may protrude partially beyond the surface of the wing, even if surrounded by a bubble or blister, which can increase drag and reduce fuel efficiency.

[0005] Ailerons, in particular, are located along the trailing edge of the wing, leaving minimal internal space available for the associated actuators. For this reason, there is a growing demand for rotary hydraulic actuators, which occupy a smaller space, for such applications. Unfortunately, previous rotary hydraulic actuators have not been able to operate sustainably without leaking fluid, potentially affecting the precise positioning of the associated ailerons, and creating numerous maintenance challenges. Summary of the Invention

[0006] The present disclosure provides a rotary actuator, a control surface actuator system including the rotary actuator, and a method for actuating a control surface of an aircraft using the rotary actuator.

[0007] In some embodiments, the present disclosure relates to a rotary actuator that includes a manifold block and a first rotor assembly attached to the manifold block. The first rotor assembly in turn includes a first rotor shaft extending into the manifold block; a plurality of arcuate pistons attached to the rotor shaft, each arcuate piston being curved at a set radial distance from the axis of rotation of the rotor shaft and 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 surround each arcuate piston; and a plurality of gland seals disposed adjacent inlets to each piston pressure chamber and creating a seal between an inner surface of the piston pressure chamber and an outer surface of an arcuate piston inserted therein, each gland seal including 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, whereby a hydraulic seal is formed between each piston pressure chamber and an arcuate piston inserted therein. The first rotor assembly is configured such that supplying hydraulic fluid to the plurality of piston pressure chambers causes an arcuate piston disposed within each piston pressure chamber to move a set radial distance about an axis of rotation of the first rotor shaft, thereby rotating the first rotor shaft.

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

[0009] In some embodiments, the present disclosure relates to a method for actuating a control surface of an aircraft. The method may include providing a rotary actuator including a manifold block and a first rotor assembly mounted to the manifold block. The first rotor assembly may include a first rotor shaft extending into the manifold block, a plurality of arcuate pistons mounted to the rotor shaft, each arcuate piston curved along a predetermined radial distance from an axis of rotation of the rotor shaft and mounted to the rotor shaft via an intermediate crank arm, and a first pressure chamber assembly coupled to the manifold block, the first pressure chambers defining a plurality of piston pressure chambers configured to receive and at least partially surround the plurality of arcuate pistons, the manifold block defining a plurality of internal channels for supplying hydraulic fluid to the piston pressure chambers, and the first rotor assembly may further include a plurality of gland seals positioned adjacent an inlet to each piston pressure chamber to create 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 a surface of the arcuate piston and a plurality of outer seals configured to engage an inner surface of the piston pressure chamber, whereby a hydraulic seal may be formed between each piston pressure chamber and an arcuate piston inserted therein. The first rotor assembly is configured such that supplying hydraulic fluid to the plurality of piston pressure chambers via the plurality of internal channels of the manifold block causes an arcuate piston disposed in each piston pressure chamber to move about an 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, with an output lug coupling the inner end of the first rotor shaft to a control surface of the aircraft.The method may further include supplying pressurized hydraulic fluid to a first pressure chamber assembly through an internal channel of the manifold block to increase hydraulic fluid pressure in a piston pressure chamber of the first pressure chamber assembly; urging an arcuate piston disposed in the piston pressure chamber of the first pressure chamber assembly to move about an axis of rotation of the first rotor shaft with the increased hydraulic fluid pressure in the piston pressure chamber to rotate the first rotor shaft; rotating the first rotor shaft to move an output lug coupled to an inner end of the first rotor shaft; and moving the output lug to actuate a control surface of the aircraft.

[0010] The features, functions, and advantages may be realized individually in various embodiments of the present disclosure or may be combined in yet further embodiments, further details of which can be seen with reference to the following description and drawings. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an aircraft identifying selected control surfaces of the aircraft. [Figure 2] FIG. 1 is a cross-sectional schematic diagram illustrating a conventional linear actuator coupled to a control surface at the trailing edge of a wing. [Figure 3] 1 depicts an exemplary rotary actuator according to the present disclosure. [Figure 4] 4 depicts the exemplary rotary actuator of FIG. 3. [Figure 5] FIG. 4 is a cross-sectional view of a manifold block of the rotary actuator of FIG. 3. [Figure 6] 4 depicts the rotor shaft, crank arm, and arcuate piston of the first rotor assembly of the exemplary rotary actuator of FIG. 3; [Figure 7] 4 depicts a pressure chamber assembly of the first rotor assembly of the exemplary rotary actuator of FIG. 3. [Figure 8]4 depicts a cutaway view of the first rotor assembly of the rotary actuator of FIG. 3 in a plane perpendicular to the axis of rotation of the rotor shaft. [Figure 9] 4 depicts a cutaway view of a piston pressure chamber of the first rotor assembly of the rotary actuator of FIG. 3; [Figure 10] FIG. 4 is a cross-sectional view of a gland seal of a piston pressure chamber of the rotary actuator of FIG. 3. [Figure 11] Illustrate the manifold block of the rotary actuator of FIG. [Figure 12] 4 depicts the rotary actuator of FIG. 3 including first and second rotary assemblies, with the first and second actuator housings omitted; [Figure 13] FIG. 1 is a schematic cross-sectional view illustrating a control surface actuator system including a rotary actuator of the present disclosure coupled to a control surface at the trailing edge of a wing. [Figure 14] 1 is a flowchart illustrating an exemplary method of actuating a control surface of an aircraft according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Various aspects and embodiments of rotary actuators, flight control surface actuation systems, and methods for actuating aircraft flight control surfaces are described below and illustrated in the associated drawings. Unless otherwise specified, the rotary actuators, systems, and methods, their individual steps and variations, may, but do not necessarily, include at least one of the structures, components, functions, and / or variations described, illustrated, and / or incorporated herein. Furthermore, unless specifically excluded, the process steps, structures, components, functions, and / or variations described, illustrated, and / or incorporated herein may be included in other similar devices and methods, including interchangeability among the disclosed embodiments. The following description of various embodiments is merely exemplary in nature and is not intended to limit the embodiments, their applications, or their uses in any way. Additionally, the advantages provided by the embodiments described below are exemplary in nature, and not all embodiments provide the same advantages or the same degree of advantages.

[0013] This detailed description includes the following sections, which immediately follow: (1) Definitions, (2) Overview, (3) Examples, Components, and Alternatives, (4) Exemplary Combinations and Further Examples, (5) Advantages, Features, and Benefits, and (6) Conclusion.

[0014] definition Unless otherwise indicated, the following definitions apply herein.

[0015] "Substantially" means generally conforming to the particular dimensions, extent, shape, concept, or other aspect modified by the term, such that the features or components need not conform exactly, as long as appropriate for their intended purpose or function. For example, a "substantially cylindrical" object means that the object resembles a cylinder but may have one or more deviations from a true cylinder.

[0016] "Comprise," "include," and "have" (and their conjugations) are used interchangeably to mean including, but not necessarily being limited to, and are open-ended terms that are not intended to exclude additional, unrecited elements or method steps.

[0017] "First," "second," and "third," etc. are used to distinguish or identify various members of a group in the order in which they are introduced in a particular context, and they are not intended to imply any ordering or numerical limitation or to be fixed identifiers of the members of the group.

[0018] "Coupled" means in a relationship in which the performance of one thing affects the performance of another, and may include permanent or releasable connection, direct or indirect connection through intervening components, but is not necessarily limited to a physical connection(s).

[0019] overview An aircraft 10 is shown in Figure 1, which includes an identification of selected primary and secondary flight control surfaces of the aircraft. The flight control surfaces of the aircraft include a rudder 12 on a vertical stabilizer 14, elevators 16 on a horizontal stabilizer 18, ailerons 20 and spoilers 22 on wings 24, and may also include slats 26 and flaps 28 on wings 24.

[0020] 2 is a partial cross-sectional view of an aileron control surface 20 combined with a 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. Because the cross-section of the wing 24 is relatively thin, even in the neutral position (A), the linear actuator 30 extends beyond the envelope of the wing 24, and then protrudes even further when actuated (B). Even when fully retracted, the actuator coupling 31 between the linear actuator 30 and the aileron 20 extends beyond the skin of the wing 24 (C).

[0021] An exemplary rotary actuator 32 configured to minimize the space required by the control surface actuator is shown in Figures 3 and 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 attached to the manifold block 34 on opposite sides thereof. As particularly shown in Figure 3, the manifold block 34 includes a mounting bracket 40 for mounting the rotary actuator 32 to and within the aircraft 10 via the manifold block 34. The rotary actuator 32 further includes an output lug 42 extending from a recess 44 formed in the manifold block 34, as shown in 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. However, the output lug 42 is directly coupled to both an inner end 45 of a first rotor shaft 46 extending from the first rotor assembly 36 and an inner end 47 of a second rotor shaft 48 extending from the second rotor assembly 38, as shown in Figure 5. In turn, the output lug 42 is further configured to be coupled to an actuator arm coupled to a control surface such that operation of the rotary actuator 32 actuates movement of that control surface.

[0022] The manifold block 34 may further include a hydraulic interface 50, which may include a number of connection ports to facilitate hydraulic coupling of the rotary actuator 32 with the hydraulic system of the aircraft 10.

[0023] The first rotor assembly 36 and the second rotor assembly 38 may each include a first actuator housing 51 and a second actuator housing 52. The actuator housings are sealingly coupled to the manifold block 34 on either side of the manifold block 34, and each actuator housing encloses the remaining components of the respective first and second rotor assembly, which will be described below with particular reference to the first rotor assembly 36.

[0024] As shown in FIG. 6 , the first rotor assembly 36 may include a first rotor shaft 46 that extends the length of the first rotor assembly 36 and into the manifold block 34, defining an axis of rotation 56 within the first actuator housing 51. A plurality of crank arms 58 may be attached to the first rotor shaft 46. Each crank arm couples 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 axis of rotation 56 of the first rotor shaft 46. The set radial distance 62 is the same for each arcuate piston 60 (as shown in FIG. 8 ).

[0025] Each of the arcuate pistons 60 may be configured to have an elongated cross-section with rounded edges and a rounded distal face opposite the end of the arcuate piston 60 that attaches to the crank arm 58. The particular shape of the arcuate pistons is not critical, provided that they are accurately and smoothly machined to precise tolerances and follow a curve 61 having a set radial distance 62. For example, the arcuate pistons 60 may have a circular cross-section (having the form of an arcuate rod), or the arcuate pistons 60 may have a square or rectangular cross-section without departing from the scope and spirit of the present disclosure.

[0026] As shown in Figure 7, the first rotor assembly 36 may 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, where each piston pressure chamber 66 is configured to receive and at least partially surround an arcuate piston 60, as shown in Figure 8. The first rotor assembly 36 may be configured to include a piston pressure chamber 66 corresponding to each arcuate piston 60 within the first rotor assembly 36.

[0027] The arcuate pistons 60 and piston pressure chambers 66 may be manufactured to precise tolerances such that each arcuate piston 60 can move within a corresponding piston pressure chamber 66 along a set radial distance 62 from the axis of rotation 56 with minimal or no contact between an outer surface 68 of the arcuate piston 60 and an inner surface 70 of the piston pressure chamber 66. In addition to eliminating destructive wear on the components of the first rotor assembly 36, such precise tolerances may help improve the hydraulic operation of the resulting rotary actuator.

[0028] Although there may be no actual physical contact between the arcuate piston 60 and the piston pressure chamber 66 as the arcuate piston 60 moves within the piston pressure chamber, the piston pressure chamber is nevertheless hydraulically sealed by the interposition of a gland seal assembly 72 between an outer surface 68 of the arcuate piston 60 and an inner surface 70 of the piston pressure chamber 66. The components of the gland seal 68 are shown in more detail in Figures 9 and 10.

[0029] Each gland seal assembly 72 is positioned adjacent an inlet 74 of a piston pressure chamber 66. The gland seal assembly 72 may thereby create a hydraulic seal between an inner surface 70 of the piston pressure chamber 66 and an outer surface 68 of the arcuate piston 60 when the arcuate piston 60 is at least partially inserted into its corresponding piston pressure chamber 66. Each gland seal assembly 72 may include a gland 76 sealed within a gland bore 78 formed within 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. When the gland seal assembly 72 is sealed within 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.

[0030] The gland 76 may be retained within the gland bore 78 by the presence of a shear wire 80 disposed between the gland 76 and an inner surface 82 of the gland bore 78. While sandwiched therebetween, the shear wire 80 simultaneously rests within a complementary groove 84 formed in the inner surface 82 and a complementary groove 86 formed in the gland 76, as shown in FIG. 10. In this manner, the interaction of the shear wire 80 with the grooves 84 and 86 ensures that the gland 76 is held securely in place, even when the arcuate piston 60 is repeatedly urged reciprocally in and out of the piston pressure chamber 66.

[0031] While the gland 76 may help facilitate the formation of the required hydraulic seal between the pressure chamber inner surface 70 and the piston outer surface 68, each gland seal may further include one or more additional inner gland seals 88 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 may further include a plurality of outer gland seals 90 positioned to engage the inner surface 82 of the gland bore 78 and configured to create a seal between the inner surface 82 and the gland 76. The outer gland seals 90 may include a plurality of O-ring seals. The construction of the gland seal assembly 72 with its multiple sealing elements not only hydraulically operates the rotary actuator 32, but also provides a hydraulic seal robust enough to prevent hydraulic fluid leakage even after repeated operation of the rotary actuator, preventing leakage that has been at least partially responsible for the inadequacies of previous rotary actuator mechanisms. The design of the gland seal assembly 72 further allows for an incremental degree of additional floating of the gland assembly relative to the gland bore 78 of the pressure chamber assembly 64, and the rotary actuator is therefore better able to tolerate dimensional deviations that fall within manufacturing tolerances.

[0032] 11 depicts the manifold block 34, which is depicted semi-transparently to show a plurality of internal channels 92 within the manifold block 34. The internal channels 92 are configured to supply hydraulic fluid to at least each of the piston pressure chambers 66 formed by the pressure chamber assembly 64. Typically, the manifold block 34 defines a first plurality of internal channels configured to supply hydraulic fluid to a first piston pressure chamber, and further defines a second plurality of internal channels configured to supply hydraulic fluid to a second piston pressure chamber. Thus, by sequentially supplying hydraulic fluid to the first and second piston pressure chambers, the first rotor shaft can be rotated and counter-rotated.

[0033] As described 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 may include a first set 94 of the plurality of arcuate pistons 60 extending in a first rotational direction about the axis of rotation 56, and a second set 96 of the plurality of arcuate pistons 60 extending in a second, opposite rotational direction about the axis of rotation 56. Typically, the first set 94 and the second set 96 of arcuate pistons are equal in number. Thus, the rotary actuator 32 may be operated by supplying hydraulic fluid to a set of first piston pressure chambers corresponding to the arcuate pistons of the first half 94, increasing hydraulic pressure in the piston pressure chambers, thereby urging each of the arcuate pistons 60 of the first half 94 out of its corresponding piston pressure chamber, resulting in rotation of the first rotor shaft 46 and actuation of the rotary actuator. Increasing hydraulic pressure in the piston pressure chambers for the arcuate pistons 60 of the first half 94 may cause the rotor shaft to rotate until each of the crank arms 58 of the arcuate pistons of the first half 94 contacts a corresponding rotation stop 98 visible in FIG. 8 .

[0034] The rotary actuator 32 may be returned to its initial configuration by releasing 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 causing reverse rotation of the first rotor shaft 46 until the crank arms 58 of the arcuate pistons 60 of the second half 96 in turn contact their corresponding rotation stops 98 and the actuator 32 returns to its initial configuration.

[0035] Actuation of the rotary actuator 32 may be achieved primarily by the alternating pressurization and depressurization of the first and second plurality of piston pressure chambers, as described above. However, because the first actuator housing 51 may be sealingly coupled to the manifold block 34 and the actuator housing 51 completely encloses the first pressure chamber assembly 64, an additional interior space is created that is bounded by an outer surface 100 of the first pressure chamber assembly 64, an outer surface 102 of the first rotor shaft 46, and an interior surface 104 of the first actuator housing 51. This interior space is referred to as a first return pressure space 106.

[0036] The plurality of arcuate pistons 60 coupled to the first rotor shaft 46 may be coupled in pairs to the first rotor shaft 46. More specifically, the plurality of arcuate pistons 60 may be coupled to the first rotor shaft 46 in an arrangement that exhibits two-fold rotational symmetry about the axis of rotation 56. That is, the arrangement of the arcuate pistons about the first rotor shaft may be symmetric about the rotation of the first rotor shaft 46, offset by 180 degrees about the axis of rotation 56. This two-fold rotational symmetry may be seen, for example, in Figures 6, 7, and 12.

[0037] As described above, the rotary actuator 32 may include a first rotor assembly 36 and a second rotor assembly 38, each coupled to opposite sides of the manifold block 34. Typically, the configuration and construction of the second rotor assembly 38 is selected to be substantially identical to that of the first rotor assembly 36 and is symmetrical to the first rotor assembly 36 through a 180-degree rotation about a vertical axis of symmetry 108 perpendicular to the axis of rotation 56, as shown by FIG. 12 . FIG. 12 depicts the rotary actuator 32 without the first actuator housing 51 and the second actuator housing 52. Because the second rotor assembly 38 is symmetrical to the first rotor assembly 36, the second rotor assembly 38 also includes a rotor shaft having an end that extends into a recess 44 formed in the manifold block 34. The output lug 42 is thereby coupled to inner ends 45 and 47 of a first rotor shaft 46 and a second rotor shaft 48, respectively.

[0038] 12 , each of the first rotor assembly 36 and the second rotor assembly 38 may include eight arcuate pistons 60 mounted on the first rotor shaft 46 and the second rotor shaft 48, respectively. Further, the eight arcuate pistons 60 mounted on each rotor shaft may include a first set of four arcuate pistons 60 extending in a first rotational direction about the axis of rotation 56 and a second set of four arcuate pistons 60 extending in a second, opposite rotational direction about the axis of rotation 56. The eight arcuate pistons 60 are further arranged in an arrangement exhibiting two-component rotational symmetry about the axis of rotation 56.

[0039] Because the rotary actuator 32 can be significantly smaller in volume than a corresponding conventional linear actuator, the rotary actuator 32 can advantageously be incorporated into a flight control surface actuator system 110, as shown in Figure 13. In that case, the rotary actuator 32 can be coupled to a flight control surface 114 of the aircraft 10. The flight control surface actuator system 110 can be configured such that operation of the rotary actuator 32 actuates movement of the flight control surface 114. Alternatively, or in addition, the rotary actuator 32 can be coupled to the flight control surface 114 via an intermediate actuator arm.

[0040] Compared to the actuator system of Figure 2, the rotary actuators 32 of flight control system 110 can be entirely enclosed within the wing 24, even with a very thin cross section, as shown in Figure 13. Flight control system 110 is therefore suitable for flight control systems for wing control surfaces, since the disclosed rotary actuators can be mounted entirely within the interior space of the associated wing structure.

[0041] The various components of the rotary actuators disclosed herein can be manufactured from any suitable material having the required physical properties, particularly any suitable material already used in the manufacture of aircraft components. In particular, the arcuate pistons of the disclosed rotary actuators can be manufactured from a stainless steel alloy, such as 15-5PH stainless steel, meeting the AMS 5659 specification. The surfaces of the arcuate pistons can be further hardened by, for example, a high-velocity oxygen-fuel (HVOF) coating containing tungsten carbide and cobalt. The glands of the gland seals can be manufactured from an aluminum-nickel-bronze alloy, for example, meeting the AMS 4640 specification.

[0042] The disclosed rotary actuators may be manufactured by any suitable machining method capable of providing the precise tolerances required for hydraulic systems, such as, for example, CNC machining. Alternatively or additionally, the pressure chamber assembly requires precise tolerances, particularly along the extending arcuate piston path, and it may be advantageous to employ additive manufacturing (i.e., 3D printing) to manufacture some or all of the components of the disclosed rotary actuators.

[0043] The rotary actuators of the present disclosure may be employed in methods for actuating aircraft control surfaces, where the reduced size, enhanced performance, and increased durability of the rotary actuators of the present disclosure may improve the actuation of aircraft control surfaces.

[0044] This section describes steps of an exemplary method for actuating aircraft control surfaces, as shown in flowchart 120 of Figure 14. Where appropriate, references are made to components and systems that may be used in performing each step. These references are for illustrative purposes and are not intended to limit the possible ways in which any particular step of the method may be performed.

[0045] It should further be noted that, based on the present disclosure, additional steps may be performed without departing from the spirit of the present disclosure. Although various steps of flowchart 120 are described below and depicted in Figure 14, such steps need not all be performed, and in some cases may be performed simultaneously or in a different order than that shown in the respective flowcharts.

[0046] The example method of Flowchart 120 may include providing a rotary actuator 32, as attempted at step 122 of Flowchart 120 and as described above. The method may further include supplying pressurized hydraulic fluid to the first pressure chamber assembly 64 via the internal channel 92 of the manifold block 34 to increase hydraulic fluid pressure in the piston pressure chamber 66 of the first pressure chamber assembly 64, as attempted at step 124 of Flowchart 120. The method may further include rotating the first rotor shaft 46 by urging the arcuate piston 66 disposed in the piston pressure chamber 66 of the first pressure chamber assembly 64 to move about the axis of rotation 56 of the first rotor shaft 46 with the increased hydraulic fluid pressure in the piston pressure chamber 66, as attempted at step 128 of Flowchart 120. The method may further include moving an output lug 42 coupled to an inboard end 45 of the first rotor shaft 46 by rotating the first rotor shaft, as attempted at step 128 of the flowchart 120. The method may further include moving an actuator interface arm 112 by moving the output lug 42, as attempted at step 130 of the flowchart 120. The method may further include actuating a control surface 114 of the aircraft by moving the actuator interface arm 112, as attempted at step 132 of the flowchart 120.

[0047] The exemplary method of actuating an aircraft control surface may optionally further include returning the aircraft control surface to its original configuration by supplying pressurized hydraulic fluid to the second plurality of piston pressure chambers 66 for the arcuate pistons 60 of the second half 96, thereby urging the second set of the plurality of arcuate pistons 96 to move in an opposite direction about the rotational axis 56 of the first rotor shaft 46, as attempted in step 134 of flowchart 120. The method may optionally further include reciprocally moving the actuator arm 112 by counter-rotating the first rotor shaft 46 and moving the output lug 42 coupling the inner end 45 of the first rotor shaft 46 to the actuator arm 112, as attempted in step 136 of flowchart 120. The method may optionally further include returning the aircraft control surfaces 114 to their original configuration by moving the actuator arms 112 to their initial positions, as attempted in step 140 of flowchart 120.

[0048] Examples, Components, and Alternatives A. Exemplary Combinations and Further Examples This section describes additional aspects and features of the disclosed rotary actuator, aircraft control surface actuation system, and method of actuating an aircraft control surface, presented without limitation as a series of paragraphs, some or all of which may be designated alphanumeric for clarity and efficiency. Each of these paragraphs may be combined in any suitable manner with one or more of the other paragraphs and / or with disclosure in other parts of this application. Some of the following paragraphs explicitly refer to and further qualify other paragraphs, providing, without limitation, some examples of suitable combinations.

[0049] A1. A rotary actuator includes a manifold block and a first rotor assembly mounted to the manifold block, the first rotor assembly including: a first rotor shaft extending into the manifold block; a plurality of arcuate pistons mounted 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 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 surround each arcuate piston; and a plurality of gland seals disposed adjacent the inlet having an arcuate groove formed therein and creating a seal between an inner surface of the piston pressure chamber and an outer surface of an arcuate piston inserted therein, each gland seal including 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, whereby a hydraulic seal is formed between each piston pressure chamber and an arcuate piston inserted therein, and the first rotor assembly is configured such that supplying hydraulic fluid to the plurality of piston pressure chambers causes an arcuate piston disposed within each piston pressure chamber to move a set radial distance about an axis of rotation of the first rotor shaft, thereby rotating the first rotor shaft.

[0050] A2. The rotary actuator of paragraph A1, wherein a first set of multiple arcuate pistons extend in a first rotational direction about the axis of rotation and a second set of multiple arcuate pistons extend in a second, opposite rotational direction about the axis of rotation, whereby supplying hydraulic fluid to first piston pressure chambers of the first set of arcuate pistons results in rotation of the first rotor shaft and supplying hydraulic fluid to second piston pressure chambers of the second set of arcuate pistons results in reverse rotation of the first rotor shaft.

[0051] 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, whereby the outer surface of the first pressure chamber assembly, the outer surface of the first rotor shaft, and the inner surface of the first actuator housing collectively define a first return pressure space.

[0052] A4. The rotary actuator of any of paragraphs A1 through A3, wherein an inner end of the first rotor shaft extends into a recess formed in the manifold block, and the rotary actuator further includes an output lug coupled to the inner end of the first rotor shaft, the output lug configured to be coupled to a control surface.

[0053] A5. The rotary actuator of any of paragraphs A1 to A4, wherein the plurality of arcuate pistons are coupled to the first rotor shaft in pairs in an arrangement having two-element rotational symmetry about the axis of rotation.

[0054] A6. The rotary actuator of any of paragraphs A1 to A5, wherein each gland seal is disposed within a gland bore formed in the interior surface of a corresponding piston pressure chamber.

[0055] A7. The rotary actuator of paragraph A6, wherein each gland seal includes a gland retained within the gland bore by a shear tension wire disposed between the gland and the gland bore that engages both the gland and the gland bore.

[0056] A8. The rotary actuator of any one of paragraphs A1 through A7, wherein the inner seal includes a rod seal.

[0057] A9. The rotary actuator of any one of paragraphs A1 through A8, wherein the plurality of outer seals includes a plurality of O-ring seals.

[0058] A10. The rotary actuator of any of paragraphs A1-A9, wherein the manifold block defines a plurality of internal channels configured to supply hydraulic fluid to the piston pressure chambers.

[0059] A11. The rotary actuator of paragraph A10, wherein the manifold block defines a first plurality of internal channels configured to supply hydraulic fluid to the first piston pressure chamber and further defines a second plurality of internal channels configured to supply hydraulic fluid to the second piston pressure chamber, such that the first rotor shaft can be rotated and counter-rotated by sequentially supplying hydraulic fluid to the first and second piston pressure chambers.

[0060] A12. The rotary actuator of any of paragraphs A1 to A11, further comprising: a second rotor assembly mounted on an opposite side of the manifold block from the first rotor assembly, the second rotor assembly being substantially symmetrical to the first rotor assembly with respect to rotation about a vertical axis perpendicular to the axis of rotation; an inner end of a second rotor shaft of the second rotor assembly extending into a recess formed in the manifold block; and the rotary actuator further comprising: output lugs coupled to the inner ends of both the first rotor shaft and the second rotor shaft, the output lugs configured to be coupled to a control surface.

[0061] A13. The rotary actuator of paragraph A12, wherein each of the first and second rotor assemblies includes eight arcuate pistons mounted on its respective rotor shaft, each of the first and second rotor assemblies including a first set of four arcuate pistons extending in a first rotational direction about the axis of rotation and a second set of four arcuate pistons extending in a second, opposite rotational direction about the axis of rotation, whereby supplying hydraulic fluid to first piston pressure chambers of the first set of four arcuate pistons for each of the first and second rotor assemblies results in rotation of the combined first and second rotor shafts, and supplying hydraulic fluid to second piston pressure chambers of the second set of four arcuate pistons for each of the first and second rotor assemblies results in counter-rotation of the combined first and second rotor shafts.

[0062] B1. 1. A control surface actuator system comprising: a control surface of an aircraft; and a rotary actuator coupled to the control surface, whereby operation of the rotary actuator actuates movement of the control surface, the rotary actuator including a manifold block and first and second rotor assemblies mounted on opposite sides of the manifold block along an axis of rotation, each of the first and second rotor assemblies including: a rotor shaft extending into the manifold block along the axis of rotation; a plurality of arcuate pistons mounted on the rotor shaft, each arcuate piston curved along a defined radial distance from the axis of rotation of the rotor shaft and attached to the rotor shaft via an intermediate crank arm; and a pressure chamber assembly coupled to the manifold block, the pressure chamber receiving and at least partially surrounding the plurality of arcuate pistons. and a plurality of gland seals disposed adjacent an inlet to each piston pressure chamber to create a seal between an inner surface of the piston pressure chamber and an arcuate piston disposed therein, each gland seal including 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, whereby a hydraulic seal is formed between each piston pressure chamber and an arcuate piston inserted therein, and each rotor assembly configured such that supplying hydraulic fluid to the plurality of piston pressure chambers causes an arcuate piston disposed within each piston pressure chamber to move about an axis of rotation and increase a volume of the piston pressure chamber, thereby rotating an associated rotor shaft.

[0063] B2. A control surface actuator system in paragraph B1, where the control surface is one of a wing aileron, elevator, rudder, spoiler, wing flap, wing slat, air brake, control horn, or trim tab.

[0064] B3. A control surface actuator system of paragraph B1 or B2 in which the rotary actuator is located entirely within the wing of the aircraft.

[0065] C1. 1. A method of actuating a control surface of an aircraft, the control surface of the aircraft being coupled to an actuator arm, the method including providing a rotary actuator including a manifold block and a first rotor assembly mounted to the manifold block, the first rotor assembly including a first rotor shaft extending into the manifold block, a plurality of arcuate pistons mounted to the rotor shaft, each arcuate piston curved along a defined radial distance from an axis of rotation of the rotor shaft and mounted to the rotor shaft via an intermediate crank arm, and a first pressure chamber assembly coupled to the manifold block, the first pressure chambers defining a plurality of piston pressure chambers configured to receive and at least partially surround the plurality of arcuate pistons, the manifold block defining a plurality of internal channels for supplying hydraulic fluid to the piston pressure chambers, the first rotor assembly further comprising: the first rotor assembly including a plurality of gland seals disposed adjacent the inlet to create a seal between an inner surface of the piston pressure chamber and an arcuate piston disposed therein, each gland seal including 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, whereby a hydraulic seal is formed between each piston pressure chamber and an arcuate piston inserted therein; and the first rotor assembly is configured such that hydraulic fluid is supplied to the plurality of piston pressure chambers via a plurality of internal channels in the manifold block to cause the arcuate pistons disposed in each piston pressure chamber to move about an axis of rotation of the first rotor shaft, thereby rotating the first rotor shaft, an inner end of the first rotor shaft extending into a recess formed in the manifold block with an output lug coupling the inner end of the first rotor shaft to an end of an actuator arm also coupled to a control surface of the aircraft; and the method further includes:a supply of pressurized hydraulic fluid to a first pressure chamber assembly to increase hydraulic fluid pressure in a piston pressure chamber of the first pressure chamber assembly, urging an arcuate piston disposed in the piston pressure chamber of the first pressure chamber assembly to move about an axis of rotation of the first rotor shaft by the increased hydraulic fluid pressure in the piston pressure chamber, thereby rotating the first rotor shaft; moving an output lug coupled to an inner end of the first rotor shaft by rotating the first rotor shaft; moving an actuator arm by moving the output lug; and actuating a control surface of the aircraft by moving the actuator arm.

[0066] C2. a first set of the plurality of arcuate pistons extending in a first rotational direction about the axis of rotation and a second set of the plurality of arcuate pistons extending in a second, opposite rotational direction about the axis of rotation, the manifold block defining a second plurality of internal channels configured to supply hydraulic fluid to second piston pressure chambers, the method further comprising supplying pressurized hydraulic fluid to the second piston pressure chambers to urge the second set of the plurality of arcuate pistons to move in opposite directions about the axis of rotation of the first rotor shaft, The method of paragraph C1, including reciprocatingly moving a first set of the arranged plurality of arcuate pistons about an axis of rotation of the first rotor shaft, thereby counter-rotating the first rotor shaft; reciprocally moving the actuator arm by counter-rotating the first rotor shaft and moving an output lug coupling an inner end of the first rotor shaft to the actuator arm; and returning the aircraft control surfaces to their original configuration by moving the actuator arm to its initial position.

[0067] C3. The method of paragraph C1 or C2, wherein providing the rotary actuator includes providing a second rotor assembly mounted on an opposite side of the manifold block from the first rotor assembly, the second rotor assembly being substantially mirror-symmetric to the first rotor assembly about a plane that bisects the manifold block perpendicular to the axis of rotation, an inner end of a second rotor shaft of the second rotor assembly extending into a recess formed in the manifold block, and an output lug further coupled to the inner end of the second rotor shaft.

[0068] C4. The method of paragraph C3, wherein providing the rotary actuator includes providing first and second rotor assemblies each including eight arcuate pistons mounted on a respective first and second rotor shaft.

[0069] C5. The method of paragraph C4, wherein providing the rotary actuator includes providing first and second rotor assemblies each including eight arcuate pistons mounted on a first and second rotor shaft, respectively, each of the first and second rotor assemblies including a first set of four arcuate pistons extending in a first rotational direction about the axis of rotation and a second set of four arcuate pistons extending in a second, opposite rotational direction about the axis of rotation, in an arrangement having bipartite rotational symmetry about the axis of rotation.

[0070] C6. The method of any one of paragraphs C1 through C5, wherein the aircraft control surface is a wing control surface and providing the rotary actuator includes mounting the rotary actuator entirely within an interior space of the wing structure.

[0071] Advantages, Features, and Benefits The rotary actuators disclosed herein, including flight control surface actuator systems including the rotary actuators and methods of actuating flight control surfaces including operation of the rotary actuators, offer significant advantages over previous linear actuator designs for actuation of aircraft flight control surfaces.

[0072] The disclosed rotary actuators are configured to directly generate rotary motion, unlike linear actuators that must mechanically convert the generated linear motion into rotary motion, which may not fit within the limitations of available operating space.

[0073] As wing thickness is reduced, the space available for control surface actuator systems, including linear actuators, is limited. At least a portion of the linear actuator may be forced to protrude outside the wing interior, requiring a blister or fairing to surround the protrusion, resulting in poor aerodynamics. The rotary actuators described herein require less operating space and can be fully integrated even within the relatively thin wing structure. Furthermore, because the actuator assembly can be positioned closer to the trailing edge of the wing, more space in the wing interior can be used for fuel capacity.

[0074] Because rotary motion is generated directly by the rotary actuator, coupling to a horn arm to provide leverage for operating the control surface is no longer necessary; the control surface can be directly actuated. Furthermore, rotary actuators exhibit higher mechanical reliability than conventional toggle links sized for the same application. The design of toggle link actuators requires that the bearings used be sized larger than rotary actuators to compensate for the nonlinear loads imposed by the actuator. The rotary actuators described herein generate significantly reduced bearing loads, resulting in less bearing friction and higher actuator reliability.

[0075] Toggle link actuators must also be attached to the spar and require structural reinforcement to provide sufficient stability to withstand the loads applied to the actuator during operation. In contrast, rotary actuator installations do not require additional reinforcement, resulting in a lighter airframe. Furthermore, rotary actuators are less susceptible to buckling loads due to their compact design.

[0076] The rotary actuators described herein are substantially improved over previous versions of rotary actuators in that the disclosed gland seals provide robust hydraulic operation without the widespread liquid leakage observed in previous systems, resulting in a rotary actuator that requires less maintenance and has an extended operating life compared to previous rotary actuators.

[0077] conclusion The above disclosure may encompass multiple individual embodiments with distinct utilities. While each of these inventions has been disclosed in its preferred form(s), numerous variations are possible and the specific embodiments disclosed and illustrated herein should not be taken in a limiting sense. As used within this disclosure, section headings are for organizational purposes only. The subject matter of the present disclosure includes all novel and inventive combinations and subcombinations of the various elements, features, functions, and / or properties disclosed herein. The following claims particularly refer to certain combinations and subcombinations that are deemed novel and inventive. Other combinations and subcombinations of features, functions, elements, and / or properties may be claimed in applications claiming priority from this or a related application. Furthermore, such claims, whether broader, narrower, equal to, or different from the scope of the claims originally filed, are deemed to be within the scope of the subject matter of the present disclosure.

Claims

1. a manifold block (34), and a first rotor assembly (36) attached to the manifold block (34); The first rotor assembly (36) a first rotor shaft (46) extending into the manifold block (34); a plurality of arcuate pistons (60) attached to the first rotor shaft, each arcuate piston (60) being curved at a set radial distance from the axis of rotation (56) of the first rotor shaft (46) and 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 assembly defining a plurality of piston pressure chambers (66), each configured to receive and at least partially surround a corresponding arcuate piston (60); a plurality of gland seals (72) disposed adjacent the inlets (74) to each piston pressure chamber (66) and creating a seal between the inner surface (70) of the piston pressure chamber (66) and the outer surface (68) of the corresponding arcuate piston inserted therein, each gland seal disposed within a gland bore formed in the inner surface of its corresponding piston pressure chamber, and each gland seal includes a gland retained within the gland bore by a shear tension wire, the shear tension wire engaging both the gland and the gland bore and disposed between the gland and the gland bore; each gland seal (72) including 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), whereby a hydraulic seal is formed between each piston pressure chamber (66) and the corresponding arcuate piston (60) inserted therein; the first rotor assembly (36) is configured such that supplying hydraulic fluid to the plurality of piston pressure chambers (66) causes the arcuate pistons (60) disposed within each piston pressure chamber (66) to move the set radial distance about the rotation axis (56) of the first rotor shaft (46), thereby rotating the first rotor shaft (46).

2. 2. The rotary actuator of claim 1, wherein the plurality of arcuate pistons includes a first set of arcuate pistons extending in a first rotational direction about the axis of rotation and a second set of arcuate pistons extending in a second, opposite rotational direction about the axis of rotation, whereby supplying hydraulic fluid to a plurality of first piston pressure chambers for the first set of arcuate pistons results in rotation of the first rotor shaft, and supplying hydraulic fluid to a second plurality of second piston pressure chambers of the second set of arcuate pistons results in counter-rotation of the first rotor shaft.

3. 3. The rotary actuator of claim 1, further comprising a first actuator housing (51) sealingly coupled to the manifold block (34) and enclosing the first pressure chamber assembly (64), whereby 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) collectively define a first return pressure space (106).

4. 4. The rotary actuator of claim 1, wherein an inner end of the first rotor shaft extends into a recess formed in the manifold block, and wherein the rotary actuator further comprises an output lug coupled to the inner end of the first rotor shaft, the output lug configured to be coupled to a control surface.

5. 5. The rotary actuator of claim 1, wherein the plurality of arcuate pistons are coupled to the first rotor shaft in pairs in an arrangement having two-element rotational symmetry about the axis of rotation.

6. 6. The rotary actuator of claim 1, wherein each gland seal is disposed within a gland bore formed in the inner surface of its corresponding piston pressure chamber.

7. 7. The rotary actuator of claim 1, wherein the manifold block (34) defines a plurality of internal channels (92) configured to supply hydraulic fluid to the piston pressure chambers (66).

8. 3. The rotary actuator of claim 2, wherein the manifold block defines a first plurality of internal channels configured to supply hydraulic fluid to the first piston pressure chamber and further defines a second plurality of internal channels configured to supply hydraulic fluid to a second piston pressure chamber, such that the first rotor shaft can be rotated and counter-rotated by sequentially supplying hydraulic fluid to the first piston pressure chamber and the second piston pressure chamber.

9. a second rotor assembly (38) attached to the manifold block (34) on the opposite side from the first rotor assembly (36); the second rotor assembly (38) is substantially symmetrical to the first rotor assembly (36) with respect to rotation about a vertical axis (108) perpendicular to the rotation axis (56); an inner end (47) of a second rotor shaft (48) of the second rotor assembly (38) extends into a recess (44) formed in the manifold block (34); 3. The rotary actuator of claim 2, further comprising: an output lug coupled to the inboard ends of both the first rotor shaft and the second rotor shaft, the output lug configured to be coupled to a control surface.

10. each of the first rotor assembly and the second rotor assembly includes eight arcuate pistons (60) mounted on its respective rotor shaft; each of the first rotor assembly and the second rotor assembly includes a first set (94) of four arcuate pistons extending in a first rotational direction about the axis of rotation (56) and a second set (96) of four arcuate pistons extending in a second, opposite rotational direction about the axis of rotation (56); 10. The rotary actuator of claim 9, whereby supplying hydraulic fluid to the first piston pressure chambers (66) of the first set (94) of four arcuate pistons for each of the first and second rotor assemblies results in rotation of the combined first and second rotor shafts, and supplying hydraulic fluid to the second piston pressure chambers of the second set (96) of four arcuate pistons for each of the first and second rotor assemblies results in counter-rotation of the combined first and second rotor shafts.

11. a control surface (114) of an aircraft (10); a rotary actuator (32) coupled to the control surface (114), whereby operation of the rotary actuator actuates movement of the control surface (114), The rotary actuator (32) a manifold block (34), and a first rotor assembly and a second rotor assembly mounted on opposite sides of the manifold block (34) along an axis of rotation (56); Each of the first rotor assembly and the second rotor assembly comprises: a rotor shaft (46, 48) extending into the manifold block (34) along the axis of rotation (56); a plurality of arcuate pistons (60) attached to the rotor shaft, each arcuate piston (60) curved along a defined radial distance from the axis of rotation (56) of the rotor shaft and 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 surround the plurality of arcuate pistons (60); a plurality of gland seals (72) disposed adjacent the inlets (74) to each piston pressure chamber (66) and creating a seal between the inner surface (70) of the piston pressure chamber and the arcuate piston (60) disposed therein, each gland seal being disposed within a gland bore formed in the inner surface of its corresponding piston pressure chamber, and each gland seal including a gland held within the gland bore by a shear tension wire, the shear tension wire engaging both the gland and the gland bore and disposed between the gland and the gland bore; each gland seal (72) including 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, whereby a hydraulic seal is formed between each piston pressure chamber (66) and the arcuate piston (60) inserted therein; and each rotor assembly is configured such that supplying hydraulic fluid to the plurality of piston pressure chambers (66) causes the arcuate piston (60) disposed within each piston pressure chamber to move about the axis of rotation (56) and increase the volume of the piston pressure chamber, thereby rotating the coupled rotor shaft.

12. 12. The flight control surface actuator system of claim 11, wherein the flight control surface (114) is one of a wing aileron, an elevator, a rudder, a spoiler, a wing flap, a wing slat, an air brake, a control horn, or a trim tab.

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