A resolver assembly for a ducted-rotor aircraft is configured to detect and measure rotation of a spindle of the aircraft. The resolver assembly includes first and second gear-driven resolvers. The first and second resolvers are coupled about a shared pivot axis and are independently pivotable about the pivot axis to maintain engagement of the first and second resolvers with the spindle of the aircraft. The resolver assembly is configured such that the first and second resolvers are biased toward the spindle. The input shafts of the first and second resolvers are spaced from the pivot axis through respective first and second distances that extend outward from the pivot axis along respective first and second radial directions. The first distance is equal to the second distance and the first radial direction is not coincident with the second radial direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

Not applicable.

BACKGROUND

Ducted-rotor aircraft have at least one ducted rotor for providing lift and propulsion forces. A ducted rotor for such an aircraft typically has internal structure that supports a motor of the aircraft, and an aerodynamic exterior skin. One or more ducted rotors may be rotatably coupled to a fuselage of such an aircraft.

DETAILED DESCRIPTION

A resolver assembly that is configured to detect and measure rotation of a spindle about a spindle axis is disclosed herein for use in ducted-rotor aircraft. It is desirable to minimize the number of separate components that make up a ducted-rotor aircraft, not only to limit the weight of the aircraft, but further to limit complexity and cost of the aircraft.

FIGS.1and2are oblique views of a ducted-rotor aircraft101. Aircraft101comprises a fuselage103with a fixed wing105that extends therefrom and a plurality of pivotable ducts107. Each duct107houses a power plant for driving an attached rotor109in rotation. Each rotor109has a plurality of blades111configured to rotate within a corresponding duct107.

The position of ducts107, and optionally the pitch of blades111, can be selectively controlled to control direction, thrust, and lift of rotors109. For example, ducts107are repositionable to convert aircraft101between a helicopter mode and an airplane mode. As shown inFIG.1, ducts107are positioned such that aircraft101is in helicopter mode, which allows for vertical takeoff and landing, hovering, and low-speed directional movement. As shown inFIG.2, ducts107are positioned such that aircraft101is in airplane mode, which allows for high-speed forward-flight.

In this embodiment, aircraft101is configured with four ducts107, including two ducts107aand107bthat form a forward pair of ducts and two ducts107cand107dthat form an aft pair of ducts. Each duct107is rotatably coupled to fuselage103of aircraft101via a spindle. Ducts107aand107bare coupled directly to fuselage103by a first spindle113. Ducts107cand107dare each rotatably coupled to a corresponding end of wing105via respective discrete spindles (not shown). As shown, ducts107cand107deach include a winglet115that is coupled thereto. It should be appreciated that aircraft101is not limited to the illustrated configuration having four ducts107, and that aircraft101may alternatively be implemented with more or fewer ducts107.

FIG.3is a front view of a portion of aircraft101, with a portion of an aerodynamic exterior skin of fuselage103removed to illustrate a duct assembly117that is configured to rotatably couple ducts107aand107bto fuselage103. As shown, duct assembly117includes duct107a, duct107b, and spindle113. Spindle113is configured to support ducts107aand107b. As shown, ducts107aand107bare fixedly coupled to opposed ends of spindle113for rotation therewith. Duct107amay be referred to as a first duct107of duct assembly117and duct107bmay be referred to as a second duct107of duct assembly117.

Spindle113includes a shaft119that extends from a first end (not shown) that is disposed in duct107ato a second end (now shown) that is disposed in duct107b. As shown, shaft119of spindle113is cylindrical. It should be appreciated however, that shaft119is not limited to the illustrated cylindrical cross-section, and that shaft119may be alternatively implemented with any other suitable geometry. Shaft119may be fabricated from aluminum or any other suitable material.

Spindle113further includes two bearings121that are mounted on shaft119. Bearings121are configured to rotatably couple spindle113to fuselage103of aircraft101. In this embodiment, fuselage103includes a pair of cradles123that are configured to receive bearings121therein. As shown, a first cradle123is located on top of fuselage103near a first side125thereof and a second cradle123is located on top of fuselage103near an opposed second side127thereof. A first one of bearings121is configured to react to radial loads, and a second one of bearings121is configured to react to both radial and axial loads.

In this embodiment, spindle113is configured to be coupled to a linear actuator (not shown) that is mounted to fuselage103. When operated, the linear actuator causes spindle113to rotate about a longitudinal spindle axis129, for example during conversion of aircraft101between airplane mode and helicopter mode. In this regard, the linear actuator may be referred to as a conversion actuator. When the linear actuator causes spindle113to rotate, ducts107aand107bexhibit equal rotational displacement relative to each other about spindle axis129.

Aircraft101further includes a resolver assembly131that is configured to detect and measure rotation of spindle113about spindle axis129.FIG.4is an oblique view of a portion of aircraft101, depicting resolver assembly131in an installed position. In this embodiment, resolver assembly131comprises a first resolver133and a second resolver135that are configured to redundantly detect and measure rotation of spindle113about spindle axis129. Preferably, first resolver133and second resolver135are gear-driven rotary variable differential transformer (RVDT) sensors. It should be appreciated that resolver assembly131is not limited to being implemented with RVDT sensors for first and second resolvers133,135, and that resolver assembly131may alternatively be implemented with one or more other types of resolvers.

In this embodiment, resolver assembly131is implemented as a dual-mount resolver assembly with gear-driven resolvers. More specifically, two resolvers are incorporated into a single mounting structure. Resolver assembly131is configured such that first resolver133and second resolver135are independently pivotable about a shared pivot axis137. Pivot axis137extends parallel to spindle axis129. This configuration enables resolver assembly131to maintain engagement of first resolver133and second resolver135with spindle113. In this embodiment, resolver assembly131is configured to be mounted to a structural member of fuselage103of aircraft101, for example as shown inFIG.4.

FIGS.5and6are right side and left side views, respectively, of resolver assembly131.FIG.7is a rear view of resolver assembly131. First resolver133comprises an input shaft139having a gear141that is coupled thereto and second resolver135comprises an input shaft143having a gear145that is coupled thereto. In this embodiment, input shaft139of first resolver133is spaced from pivot axis137through a first distance147along a first radial direction149that extends perpendicularly outward from a center of pivot axis137toward a central axis of input shaft139. Input shaft143of second resolver135is spaced from pivot axis137through a second distance151along a second radial direction153that extends perpendicularly outward from pivot axis137toward a central axis of input shaft143. In this embodiment, first distance147is equal to second distance151, such that input shaft139of first resolver133and input shaft143of second resolver135are spaced equally from pivot axis137relative to each other. Furthermore, first radial direction149is not coincident with second radial direction153. Stated differently, first radial direction149and second radial direction153are angularly offset about pivot axis137relative to each other.

In this embodiment, resolver assembly131further comprises a base155, a first carrier157to which first resolver133is fixedly mounted, and a second carrier159to which second resolver135is fixedly mounted. As shown, first resolver133and second resolver135are secured to first carrier157and second carrier159, respectively, via bolts161. It should be appreciated that one or both of first resolver133and second resolver135may be alternatively secured to respective carriers, for example using another type of fastener.

First carrier157and second carrier159are coupled to base155such that first carrier157and second carrier159are independently pivotable relative to each other about pivot axis137. In this embodiment, base155defines a clevis163, first carrier157defines a clevis165, and second carrier159defines a clevis167. Clevis167of second carrier159is configured to be received within clevis165of first carrier157, and clevis165of first carrier157is configured to be received within clevis163of base155. Each of clevis163,165, and167define respective apertures (not shown) that extend therethrough, the apertures configured to receive a clevis pin169that couples together base155, first carrier157, and second carrier159and defines pivot axis137. It should be appreciated that base155, first carrier157, and second carrier159are not limited to the respective illustrated configurations. For example, one or more of base155, first carrier157, and second carrier159may be alternatively configured to otherwise interconnect with one another about a shared pivot axis. Furthermore, one or both of first carrier157and second carrier159may be alternatively configured to allow the mounting of resolvers having configurations that differ from those shown.

Base155is configured to be mounted to a structural member of fuselage103of aircraft101. In this embodiment, base155defines a mounting bracket171that is configured to be secured to a structural member of fuselage103using fasteners, such as bolts. Mounting bracket171defines a first surface173and a second surface175that are each configured to abut a corresponding surface of the structural member of fuselage103when resolver assembly131is in a mounted position relative to the structural member.

Aircraft101further includes an engagement component177that is configured to engage with first resolver133and second resolver135during rotation of spindle113, thereby enabling first resolver133and second resolver135to detect and measure rotation of spindle113about spindle axis129. In this embodiment, engagement component177comprises a body179in the form of an arc-shaped rib181that is configured to be mounted in a fixed position to spindle113. Body179extends from a first end183to a second end185and defines a curved inner surface187that conforms to a corresponding portion of an outer surface of spindle113. Body179further defines a plurality of gear teeth189that extend along an outer circumference of rib181. Stated differently, body179has an arc-shaped outer surface that defines plurality of gear teeth189. Gear141of first resolver133and gear145of second resolver135each define a respective plurality of gear teeth191that are complementary to and configured to engage (e.g., mesh) with plurality of gear teeth189of rib181.

In operation, for example during conversion of aircraft101between helicopter mode and airplane mode, as spindle113pivots about spindle axis129, respective gear teeth189of rib181mesh with gear teeth191of gear141of first resolver133and gear145of second resolver135, thereby causing input shaft139of first resolver133and input shaft143of second resolver135to rotate in tandem with spindle113. First and second resolvers133,135translate the rotation of input shafts139,143, respectively, into respective measurements of angular displacement of spindle113that are reported to one or more systems of aircraft101. Gear teeth189of engagement component177have a width that is wider than that of gears141and145, such that engagement between gears141and145may be maintained if one or both of gears141and145and/or engagement component177move relative to each other along a longitudinal direction that extends parallel to spindle axis129, for example during rotation of spindle113.

In this embodiment, engagement component177is configured to be mounted to spindle113in a fixed position using fasteners, such as bolts. More specifically, body179defines a plurality of apertures193that extend therethrough, each aperture193configured to receive a fastener. In this regard, engagement component177is carried by spindle113. Engagement component177and resolver assembly131may be implemented as a resolver system195. It should be appreciated that engagement component177is not limited to the illustrated geometry of rib181, and that engagement component177may alternatively be configured with any other suitable geometry. Moreover, it should further be appreciated that spindle113may be alternatively configured with an integral engagement component, for example a plurality of gear teeth that are integral with spindle113and that extend along a portion of an outer surface of spindle113. In this regard, the plurality of gear teeth are carried by spindle113.

Resolver assembly131is configured such that first resolver133and second resolver135are biased toward spindle113, and in particular against engagement component177. Biasing first resolver133and second resolver135toward spindle113isolates vibration and maintains engagement of first and second resolvers133,135with engagement component177. In this embodiment, resolver assembly131includes a pair of springs197that bias first and second resolvers133,135against spindle113. Each of first carrier157and second carrier159defines a tab199that extends rearward therefrom, each tab199having a post201coupled thereto that carries a corresponding one of the springs197. First carrier157and second carrier159are each biased toward spindle113by a respective one of the springs197. In this regard, resolver assembly131may be referred to as a spring-loaded resolver assembly.

In operation, for example during conversion of aircraft101between helicopter mode and airplane mode, if all or a portion of spindle113moves such that spindle axis129is displaced from its natural alignment, respective forces may be applied to one or both of first resolver133and second resolver135by engagement component177. In response to the application of such forces, one or both of first carrier157and second carrier159may pivot about pivot axis137. When spindle113subsequently returns to its natural position, thereby returning spindle axis129to its natural alignment, one or both of first carrier157and second carrier159may be biased toward engagement component177, thereby maintaining engagement between first and second resolvers133,135and engagement component177.

In this embodiment, resolver assembly131further includes a pair of backstops203. Each backstop203limits how far a corresponding one of first carrier157and second carrier159can pivot about pivot axis137. Each backstop203is configured to, once a corresponding one of first carrier157or second carrier159has pivoted through a predetermined maximum pivot angle, prevent further pivoting of corresponding first carrier157or second carrier159. Each backstop203comprises a shaft205that is coupled to a corresponding tab199of first carrier157or second carrier159. Each shaft205is received in a corresponding portion of base155such that shaft205is translatable along a linear direction in and out of base155. When one of first carrier157or second carrier159pivots about pivot axis137such that shaft205of a corresponding backstop203travels through a predetermined maximum linear travel distance that equates to the maximum pivot angle, respective portions of backstop203abut each other, such that further pivoting of first carrier157or second carrier159is prevented.

The predetermined maximum linear travel distance of shaft205of each backstop203may be fixed. Alternatively, backstops203may be implemented as adjustable backstops. In this embodiment, the maximum linear travel distance of shaft205of each backstop203may be set via rotation of a respective adjustment nut207. Setting respective predetermined maximum pivot angles may prevent one or both of first carrier157and second carrier159from pivoting far enough that respective gear teeth191of one or both of gear141and gear145become disengaged from gear teeth189of engagement component177, such that one or both of gear141and gear145skip one or more gear teeth189prior to reengaging with engagement component177when biased toward spindle113by springs197.

FIG.8is a side view of an alternative embodiment of a resolver assembly209that may be implemented with aircraft101, for example in lieu of resolver assembly131, to detect and measure rotation of spindle113about spindle axis129. Resolver assembly209comprises a first resolver211, a second resolver213, and a third resolver215that are configured to redundantly detect and measure rotation of spindle113about spindle axis129. Preferably, first resolver211, second resolver213, and third resolver215are gear-driven rotary variable differential transformer (RVDT) sensors. It should be appreciated that resolver assembly209is not limited to being implemented with RVDT sensors for first, second, and third resolvers211,213, and215, and that resolver assembly209may alternatively be implemented with one or more other types of resolvers.

Resolver assembly209is configured such that first resolver211, second resolver213, and third resolver215are independently pivotable about a shared pivot axis217. Pivot axis217extends parallel to spindle axis129. This configuration enables resolver assembly209to maintain engagement of first resolver211, second resolver213, and third resolver215with spindle113. Resolver assembly209is configured to be mounted to a structural member of fuselage103of aircraft101.

First resolver211comprises an input shaft219having a gear221that is coupled thereto, second resolver213comprises an input shaft223having a gear225that is coupled thereto, and third resolver215comprises an input shaft227having a gear229that is coupled thereto. Input shaft219of first resolver211is spaced from pivot axis217through a first distance231along a first radial direction that extends perpendicularly outward from a center of pivot axis217toward a central axis of input shaft219. Input shaft223of second resolver213is spaced from pivot axis217through a second distance233along a second radial direction that extends perpendicularly outward from pivot axis217toward a central axis of input shaft223. Input shaft227of third resolver215is spaced from pivot axis217through a third distance235along a third radial direction that extends perpendicularly outward from pivot axis217toward a central axis of input shaft227. First distance231is equal to third distance235, such that input shaft219of first resolver211and input shaft227of third resolver215are spaced equally from pivot axis217relative to each other. Second distance233is shorter than first distance231and third distance235. Furthermore, the first radial direction, second radial direction, and third radial direction are not coincident with each other. Stated differently, the first, second, and third radial directions are angularly offset about pivot axis217relative to each other.

Resolver assembly209further comprises a base155, a first carrier239to which first resolver211is fixedly mounted, a second carrier241to which second resolver213is fixedly mounted, and a third carrier243to which third resolver215is fixedly mounted. First carrier239, second carrier241, and third carrier243are coupled to base237such that first carrier239, second carrier241, and third carrier243are independently pivotable relative to each other about pivot axis217. It should be appreciated that base237, first carrier239, second carrier241, and third carrier243are not limited to the respective illustrated configurations. Base237is configured to be mounted to a structural member of fuselage103of aircraft101.

Resolver assembly209is configured to engage with an engagement component245. Engagement component245may be configured similarly to engagement component177, for example similarly or identically to rib181. Engagement component245engages with first resolver211, second resolver213, and third resolver215, and in particular gears221,225, and229thereof, during rotation of spindle113, thereby enabling first resolver211, second resolver213, and third resolver215to detect and measure rotation of spindle113about spindle axis129. Resolver assembly209is configured such that first resolver211, second resolver213, and third resolver215are biased, for example using springs (not shown) toward spindle113, and in particular against engagement component245. Biasing first resolver211, second resolver213, and third resolver215toward spindle113isolates vibration and maintains engagement of first, second, and third resolvers211,213,215with engagement component245. Resolver assembly209may be implemented with backstops (not shown), such as adjustable backstops, that limit how far one or more of first carrier239, second carrier241, and third carrier243can pivot about pivot axis217.

FIG.9is a front view of another alternative embodiment of a resolver assembly247that may be implemented with aircraft101, for example in lieu of resolver assembly131, to detect and measure rotation of spindle113about spindle axis129. Resolver assembly247comprises a first resolver249and a second resolver251that are configured to redundantly detect and measure rotation of spindle113about spindle axis129. Preferably, first resolver249and second resolver251are gear-driven rotary variable differential transformer (RVDT) sensors. It should be appreciated that resolver assembly247is not limited to being implemented with RVDT sensors for first resolver249and second resolver251, and that resolver assembly247may alternatively be implemented with one or more other types of resolvers.

Resolver assembly247is configured such that first resolver249and second resolver251are independently pivotable about a shared pivot axis253. Pivot axis253extends parallel to spindle axis129. This configuration enables resolver assembly247to maintain engagement of first resolver249and second resolver251with spindle113. Resolver assembly247is configured to be mounted to a structural member of fuselage103of aircraft101.

First resolver249comprises an input shaft255having a gear257that is coupled thereto and second resolver251comprises an input shaft259having a gear261that is coupled thereto. Input shaft255of first resolver249is spaced from pivot axis253through a first distance263along a first radial direction that extends perpendicularly outward from a center of pivot axis253toward a central axis of input shaft255. Input shaft259of second resolver251is spaced from pivot axis253through a second distance265along a second radial direction that extends perpendicularly outward from pivot axis253toward a central axis of input shaft259. First distance263is equal to second distance265, such that input shaft255of first resolver249and input shaft259of second resolver251are spaced equally from pivot axis253relative to each other. Furthermore, the first radial direction and second radial direction are coincident with each other.

Resolver assembly247further comprises a base267, a first carrier269to which first resolver249is fixedly mounted, and a second carrier271to which second resolver251is fixedly mounted. First carrier269and second carrier271are coupled to base267such that first carrier269and second carrier271are independently pivotable relative to each other about pivot axis253. It should be appreciated that base267, first carrier269, and second carrier271are not limited to the respective illustrated configurations. Base267is configured to be mounted to a structural member of fuselage103of aircraft101.

Resolver assembly247is configured to engage with an engagement component273. Engagement component273may be configured similarly to engagement component177, for example similarly to rib181. Engagement component273engages with first resolver249and second resolver251, and in particular gears257and261thereof, during rotation of spindle113, thereby enabling first resolver249and second resolver251to detect and measure rotation of spindle113about spindle axis129. Resolver assembly247is configured such that first resolver249and second resolver251are biased, for example using springs (not shown) toward spindle113, and in particular against engagement component273. Biasing first resolver249and second resolver251toward spindle113isolates vibration and maintains engagement of first and second resolvers249,251with engagement component273. Resolver assembly247may be implemented with backstops (not shown), such as adjustable backstops, that limit how far one or more of first carrier269and second carrier271can pivot about pivot axis253.

FIG.10is a front view of still another alternative embodiment of a resolver assembly275that may be implemented with aircraft101, for example in lieu of resolver assembly131, to detect and measure rotation of spindle113about spindle axis129. Resolver assembly275comprises a first resolver277and a second resolver279that are configured to redundantly detect and measure rotation of spindle113about spindle axis129. Preferably, first resolver277and second resolver279are gear-driven rotary variable differential transformer (RVDT) sensors. It should be appreciated that resolver assembly275is not limited to being implemented with RVDT sensors for first resolver277and second resolver279, and that resolver assembly275may alternatively be implemented with one or more other types of resolvers.

Resolver assembly275is configured such that first resolver277and second resolver279are independently pivotable about a shared pivot axis281. Pivot axis281extends parallel to spindle axis129. This configuration enables resolver assembly275to maintain engagement of first resolver277and second resolver279with spindle113. Resolver assembly275is configured to be mounted to a structural member of fuselage103of aircraft101.

First resolver277comprises an input shaft283having a gear285that is coupled thereto and second resolver279comprises an input shaft289having a gear291that is coupled thereto. Input shaft283of first resolver277is spaced from pivot axis281through a first distance293along a first radial direction that extends perpendicularly outward from a center of pivot axis281toward a central axis of input shaft283. Input shaft289of second resolver279is spaced from pivot axis281through a second distance295along a second radial direction that extends perpendicularly outward from pivot axis281toward a central axis of input shaft289. First distance293is equal to second distance295, such that input shaft283of first resolver277and input shaft289of second resolver279are spaced equally from pivot axis281relative to each other. Furthermore, the first radial direction and second radial direction are coincident with each other.

Resolver assembly275further comprises a base297, a first carrier299to which first resolver277is fixedly mounted, and a second carrier301to which second resolver279is fixedly mounted. First carrier299and second carrier301are coupled to base297such that first carrier299and second carrier301are independently pivotable relative to each other about pivot axis281. It should be appreciated that base297, first carrier299, and second carrier301are not limited to the respective illustrated configurations. Base297is configured to be mounted to a structural member of fuselage103of aircraft101.

Resolver assembly275is configured to engage with a first engagement component303and a second engagement component305. More specifically, resolver assembly275is configured such that first resolver277engages with first engagement component303and second resolver279engages with second engagement component305. One or both of first and second engagement components303,305may be configured similarly to engagement component177, for example similarly to rib181. Engagement components303and305engage with first resolver277and second resolver279, respectively, and in particular gears285and291thereof, during rotation of spindle113, thereby enabling first resolver277and second resolver279to detect and measure rotation of spindle113about spindle axis129. Resolver assembly275is configured such that first resolver277and second resolver279are biased, for example using springs (not shown) toward spindle113, and in particular against engagement components303and305, respectively. Biasing first resolver277and second resolver279toward spindle113isolates vibration and maintains engagement of first resolver277with engagement component303and engagement of second resolver279with engagement component305. Resolver assembly275may be implemented with backstops (not shown), such as adjustable backstops, that limit how far one or more of first carrier299and second carrier301can pivot about pivot axis281.

It should be appreciated that while resolver assemblies, such as resolver assemblies131,209,247, and275are illustrated and described herein as implemented for measuring angular displacement of ducts107(e.g., by measuring rotation of spindle113) that a resolver assembly may alternatively be implemented to measure rotation of other shafts in an aircraft.

At least one embodiment is disclosed, and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of this disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of this disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, Rl, and an upper limit, Ru, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=Rl+k*(Ru−Rl), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 95 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed.

Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention. Also, the phrases “at least one of A, B, and C” and “A and/or B and/or C” should each be interpreted to include only A, only B, only C, or any combination of A, B, and C.