Patent Description:
Actuator assemblies, such as rotary actuator assemblies, may change position following failure of an input signal or pressure source, thereby moving from a last-commanded position before the failure. As such, in certain apparatuses, such as turbo machines, actuator assemblies coupled to variable vane assemblies may undesirably enable movement of the vane assembly following failure of the actuator assembly, such as loss of an electrical input signal or motive pressure source. Failure of the actuator assembly may therefore compound into failures at the turbo machine by undesirably allowing uncommanded changes in vane angle due to loss of actuator assembly control. Such uncommanded changes may adversely affect turbo machine operation, including stall or surge.

Additionally, or alternatively, there is a need for fail fix systems that reduce weight and complexity over known systems that may include multiple components separate or from the actuator assembly or housing.

As such, there is a need for fail fix systems for actuator assemblies that disable or mitigate undesired movement of the system following failure of an input control. <CIT> discloses a rotary actuator with a fail-safe internal break mechanism. <CIT> discloses a brake for mechanical devices, particularly a face tooth piston brake. <CIT> discloses another fail-safe brake for a rotary actuator.

An aspect of the present invention is directed to a rotary actuator assembly according to claim <NUM>.

Another aspect of the present invention is directed to an apparatus for fail fix actuation according to claim <NUM>.

Approximations recited herein may include margins based on one more measurement devices as used in the art, such as, but not limited to, a percentage of a full scale measurement range of a measurement device or sensor. Alternatively, approximations recited herein may include margins of <NUM>% of an upper limit value greater than the upper limit value or <NUM>% of a lower limit value less than the lower limit value.

Embodiments of an actuator assembly including a fail fix system that may disable or mitigate undesired movement of the actuator system following failure of an input control are generally provided. The actuator assembly shown and described herein provides a system within a rotary actuator assembly to disable or mitigate undesired movement of the rotary actuator output shaft following failure of an input control signal. Embodiments of the actuator assembly include a stop collar or servo piston keyed or slotted into a surrounding body to prevent rotation of the collar or piston. A spring is incorporated onto the first end of the piston maintains the piston loaded onto a vane shaft or input drive assembly. A control valve assembly, such as a control solenoid valve, provides a motive fluid to a second end of the piston opposite of the first end such as to balance the load applied from the spring during non-failed operation of the actuator assembly.

Following loss of signal from the control valve assembly, the motive fluid is discontinued to the second end of the piston and the spring is allowed to apply a compressive force to move the piston to the vane shaft or input drive assembly. A friction mechanism, such as a friction disc or tooth geometry, at the second end of the piston engages the input drive assembly. The piston, slotted or keyed into the surrounding body, now engaged with the input drive assembly, prevents rotation of the input drive assembly and therefore the output shaft. The minimal distance between the second end of the piston and the input drive assembly mitigates an amount of movement that may occur following control signal failure. As such, undesired movement of an apparatus attached to the actuator assembly, such as a vane assembly, is mitigated or disabled. Additionally, or alternatively, the last commanded position of the output shaft is substantially maintained following loss of control signal.

When incorporated into a turbo machine, embodiments of the actuator assembly shown and described herein may mitigate stalls, surges, or other undesired operation of the turbo machine that may result from undesired changes in vane angle at a vane assembly following loss of control signal.

Referring now to the drawings, <FIG> provide comparative examples useful for understanding the invention, and <FIG> provide exemplary embodiments of an actuator assembly <NUM> according to aspects of the present disclosure. The actuator assembly <NUM> includes an output shaft <NUM> coupled to an input drive assembly <NUM>. The output shaft <NUM> is extended through a piston assembly <NUM> within a surrounding body <NUM>. The body <NUM> defines a first end <NUM> separated laterally from a second end <NUM> with a stop collar or servo-controlled piston <NUM> therebetween. The piston assembly <NUM> is detachably coupled at the second end <NUM> to the input drive assembly <NUM>. In various embodiments, the input drive assembly <NUM> includes an actuator mechanism <NUM> and input shaft <NUM> detachably coupled to the piston assembly <NUM>. In one embodiment, the actuator mechanism <NUM> includes an actuator vane assembly defining a rotary type actuator drive by a motive fluid. The motive fluid may include one or more of a lubricant or hydraulic fluid or a pneumatic fluid, or another suitable motive fluid to actuate of the input drive assembly <NUM> and rotate or otherwise displace the output shaft <NUM>.

The piston assembly <NUM> including the stop collar or servo-controlled piston <NUM> is moveable within the body <NUM> surrounding the piston <NUM>. The piston <NUM> is moveable within the body <NUM> between the opposing ends <NUM>, <NUM> within the body <NUM> of the piston assembly <NUM>, such as further described below. The surrounding body <NUM> is keyed or otherwise grooved <NUM> laterally between first end <NUM> and the second end <NUM>. The piston <NUM> defines a key or other raised structure in the groove <NUM> such as to prevent rotation of the piston <NUM>. A friction mechanism <NUM> is coupled to the piston <NUM> at the second end <NUM>. The piston <NUM> is releaseably coupled to the input shaft <NUM> of the input drive assembly <NUM> via the friction mechanism <NUM>. <FIG> and <FIG> each depict the piston assembly <NUM> disengaged from the input drive assembly <NUM>. <FIG> and <FIG> each depict the piston assembly <NUM> engaged with the input drive assembly <NUM>. Together, <FIG> and <FIG> depict the piston assembly <NUM> releaseably engaged to the input drive assembly <NUM> such as further described herein.

In <FIG>, the friction mechanism <NUM> defines a clutch mechanism or friction disc configured to engage the input drive assembly <NUM> when the piston <NUM> is moved onto the input drive <NUM>. The friction mechanism <NUM> defining a friction disc includes a minimal stroke or area <NUM> between the friction mechanism <NUM> at the second end <NUM> and the input drive assembly <NUM>, such as to improve fail safe position and response time such as further described below.

In an embodiment, such as depicted in regard to <FIG>, the friction mechanism <NUM> defines a notched tooth or serrated geometry at the input drive assembly <NUM> and the piston <NUM>. The serrated geometry of the friction mechanism <NUM> may provide improved mechanical engagement force for disabling undesired rotation of the output shaft <NUM>. The friction mechanism <NUM> defining the friction disc (<FIG>) may provide an improved response time relative to the serrated geometry (<FIG>), such as to enable the minimum stroke or area <NUM> between the second end <NUM> of the piston <NUM> to be less than the tooth height of the serrated geometry. As further described herein, the piston <NUM> may displace toward the second end <NUM> to contact the input drive assembly <NUM>. The input drive assembly <NUM> may rotate only insofar as the friction mechanism <NUM>, such as the serrated geometry, may allow (e.g., corresponding to the tooth geometry depicted in <FIG>).

Referring to <FIG> and <FIG>, the actuator assembly <NUM> includes a spring <NUM> coupled at the first end <NUM> of the piston <NUM> and the body <NUM>. The spring <NUM> is disposed within the body <NUM> of the piston assembly <NUM> such as to act against the body <NUM> and the first end <NUM> of the piston <NUM>. An opening <NUM> is defined through the body <NUM> in fluid communication with the area <NUM> within the body <NUM>. The opening <NUM> is further defined at the second end <NUM> between the piston <NUM> and the input drive assembly <NUM>, such as to receive and egress a fluid <NUM> within the area <NUM> such as further described below.

Referring to <FIG>, a schematic embodiment of the actuator assembly <NUM> further including a control valve assembly <NUM> is depicted. The control valve assembly <NUM> includes a first input pressure opening <NUM> configured to receive a liquid or gaseous motive fluid, depicted schematically via arrows <NUM>. The motive fluid <NUM> may generally include a hydraulic or pneumatic high pressure source, such as in fluid communication with the input drive assembly <NUM> to rotate or displace the output shaft <NUM>.

During non-failed operation of the actuator assembly <NUM> or surrounding apparatus <NUM>, an electrical signal is applied to the control valve assembly <NUM> to disable pressure or force from the motive fluid <NUM>, such as via closing the input opening <NUM> at the control valve assembly <NUM> through which the motive fluid <NUM> may enter the control valve assembly <NUM>. The control valve assembly <NUM> is actuated such as to enable at least a portion of the motive fluid, shown schematically via arrows <NUM>, to flow from an opening <NUM> at the control valve assembly <NUM> into the area <NUM> within the body <NUM> between the piston <NUM> and the input drive assembly <NUM> at the second end <NUM>, such as depicted in regard to <FIG>. The spring <NUM> provides a compressive force toward the input drive assembly <NUM> and the motive fluid <NUM> provides a counteracting force such as to prevent coupling of the piston <NUM> to the input drive assembly <NUM> at the friction mechanism <NUM>. In other words, pressure on opposing sides <NUM>, <NUM> of the piston <NUM> is substantially equal and opposite during non-failed operation. The motive fluid <NUM> permits the piston <NUM> to displace away from the input drive assembly <NUM> such as to enable free movement of the input drive assembly <NUM> and the output shaft <NUM> coupled thereto.

Referring now to <FIG>, following loss of an electrical signal to the control valve assembly <NUM>, the control valve assembly <NUM> is no longer energized and, as such, the motive fluid <NUM> input to the control valve assembly <NUM> is allowed to displace the control valve assembly <NUM> such as to discontinue pressurized output of the motive fluid <NUM> from the control valve assembly <NUM> and enable the input motive fluid <NUM> from the control valve <NUM> to enter the plenum <NUM> (depicted schematically via arrows <NUM>) such as to reduce the area <NUM> at the second end <NUM> of the body <NUM>. The de-pressurized fluid <NUM> is returned from the body <NUM> to the control valve assembly <NUM> via the force exerted by the spring <NUM> and the motive fluid <NUM> in the plenum <NUM> toward the input drive assembly <NUM>, and reducing the area <NUM> between the piston <NUM> and the input drive assembly <NUM>. The area <NUM> is closed as the friction mechanism <NUM> establishes contact of the piston <NUM> to the input drive assembly <NUM>, thereby disabling undesired or additional rotation of the output shaft <NUM> following failure of a control system or other input power or actuation source.

Various embodiments of the piston <NUM> may define a half-area servo piston enabling movement away from the input drive assembly <NUM> (e.g., toward the first end <NUM>) when substantially equal pressure is applied to the opposing ends <NUM>, <NUM> or the plenum <NUM> and the area <NUM>, thereby allowing freedom of movement of the input drive assembly <NUM>. For example, the half-area servo piston may be defined smaller relative to the input drive assembly <NUM>. In other embodiments, the piston <NUM> may define a non-half area servo piston applying a demanded loading to either or both ends <NUM>, <NUM> of the piston <NUM>.

It should be appreciated that features illustrated or described as part of <FIG> may be used with features illustrated as part of <FIG>, or further in regard to the apparatus of <FIG> described further below. For example, the control valve <NUM> depicted in regard to <FIG> may be used and operated in regard to the examples shown and described in regard to <FIG>. As another example, one or more controllers configured to provide and/or receive signals to and from the actuator assembly <NUM> and/or further including the control valve <NUM> may be configured as part of the apparatus further described in regard to <FIG> below.

<FIG> is a schematic partially cross-sectioned side view of an exemplary apparatus <NUM> at which embodiments of the actuator assembly <NUM> may be incorporated. Although generally depicted herein as a gas turbine engine defining a turbofan configuration, the apparatus <NUM> shown and described herein may define any system including an actuation system such as described herein. Additionally, or alternatively, although depicted as a gas turbine engine defining a turbofan, the apparatus <NUM> may define a turbo machine generally, or more specifically a turbojet, turboprop, or turboshaft gas turbine engine configuration, including those for industrial or marine use, or a steam turbine engine. As shown in <FIG>, the apparatus <NUM> has a longitudinal or axial centerline axis <NUM> that extends there through for reference purposes. An upstream end <NUM> and a downstream end <NUM> are each defined for reference purposes, generally denoting a direction from which air enters into the apparatus <NUM> (i.e., the upstream end <NUM>) and a direction to which air exits the apparatus <NUM> (i.e., the downstream end <NUM>). In general, the apparatus <NUM> may include a fan assembly <NUM> and a core engine <NUM> disposed downstream of the fan assembly <NUM>.

The core engine <NUM> may generally include a substantially tubular outer casing <NUM> that defines an annular inlet <NUM>. The outer casing <NUM> encases or at least partially forms, in serial flow relationship, a compressor section <NUM> having a booster or low pressure (LP) compressor <NUM>, a high pressure (HP) compressor <NUM>, or one or more intermediate pressure (IP) compressors (not shown) disposed aerodynamically between the LP compressor <NUM> and the HP compressor <NUM>; a combustion section <NUM>; a turbine section <NUM> including a high pressure (HP) turbine <NUM>, a low pressure (LP) turbine <NUM>, and/or one or more intermediate pressure (IP) turbines (not shown) disposed aerodynamically between the HP turbine <NUM> and the LP turbine <NUM>; and a jet exhaust nozzle section <NUM>. A high pressure (HP) rotor shaft <NUM> drivingly connects the HP turbine <NUM> to the HP compressor <NUM>. A low pressure (LP) rotor shaft <NUM> drivingly connects the LP turbine <NUM> to the LP compressor <NUM>. In other embodiments, an IP rotor shaft drivingly connects the IP turbine to the IP compressor (not shown). The LP rotor shaft <NUM> may also, or alternatively, be connected to a fan shaft <NUM> of the fan assembly <NUM>. In particular embodiments, such as shown in <FIG>, the LP shaft <NUM> may be connected to the fan shaft <NUM> via a power or reduction gear assembly <NUM> such as in an indirect-drive or geared-drive configuration.

Combinations of the compressors <NUM>, <NUM>, the turbines <NUM>, <NUM>, and the shafts <NUM>, <NUM>, <NUM> each define a rotor assembly of the apparatus <NUM>. For example, in various embodiments, the LP turbine <NUM>, the LP shaft <NUM>, the fan assembly <NUM> and/or the LP compressor <NUM> together define the rotor assembly as a low pressure (LP) rotor assembly. The rotor assembly may further include the fan rotor <NUM> coupled to the fan assembly14 and the LP shaft <NUM> via the gear assembly <NUM>. As another example, the HP turbine <NUM>, the HP shaft <NUM>, and the HP compressor <NUM> may together define the rotor assembly as a high pressure (HP) rotor assembly. It should further be appreciated that the rotor assembly may be defined via a combination of an IP compressor, an IP turbine, and an IP shaft disposed aerodynamically between the LP rotor assembly and the HP rotor assembly.

As shown in <FIG>, the fan assembly <NUM> includes a plurality of fan blades <NUM> that are coupled to and that extend radially outwardly from the fan shaft <NUM>. An annular fan casing or nacelle <NUM> circumferentially surrounds the fan assembly <NUM> and/or at least a portion of the core engine <NUM>. It should be appreciated by those of ordinary skill in the art that the nacelle <NUM> may be configured to be supported relative to the core engine <NUM> by a plurality of circumferentially-spaced outlet guide vanes or struts <NUM>. Moreover, at least a portion of the nacelle <NUM> may extend over an outer portion of the core engine <NUM> so as to define a bypass airflow passage <NUM> therebetween.

During operation of the apparatus <NUM>, a volume of air as indicated schematically by arrows <NUM> enters the apparatus <NUM> through an associated inlet <NUM> of the nacelle <NUM> and/or fan assembly <NUM>. As the air <NUM> passes across the fan blades <NUM> a portion of the air as indicated schematically by arrows <NUM> is directed or routed into the bypass airflow passage <NUM>, through which most propulsive thrust is generally generated, while another portion of the air as indicated schematically by arrow <NUM> is directed or routed into the LP compressor <NUM>. Air <NUM> is progressively compressed as it flows through the LP and HP compressors <NUM>, <NUM> towards the combustion section <NUM>.

Referring still to <FIG>, the combustion gases <NUM> generated in the combustion section <NUM> flows to the HP turbine <NUM> of the turbine section <NUM>, thus causing the HP shaft <NUM> to rotate, thereby supporting operation of the HP compressor <NUM>. As shown in <FIG>, the combustion gases <NUM> are then routed to the LP turbine <NUM>, thus causing the LP shaft <NUM> to rotate, thereby supporting operation of the LP compressor <NUM> and rotation of the fan shaft <NUM>. The combustion gases <NUM> are then exhausted through the jet exhaust nozzle section <NUM> of the core engine <NUM> to provide propulsive thrust.

As operation of the apparatus <NUM> transitions from rest or zero RPM to startup and ignition, a minimum steady state operating condition (i.e., minimum steady state air and fuel flow through the core engine <NUM> to sustain approximately zero acceleration), a maximum steady state operating condition (i.e., maximum steady state air and fuel flow through the core engine <NUM> to sustain approximately zero acceleration), or one or more intermediate steady state operating conditions therebetween, the actuator assembly <NUM> may be incorporated at a variable vane assembly <NUM> at the apparatus <NUM> to adjust an angle of attack or a rotational angle of axially separated stages of vanes (e.g., vanes at one or more of the fan section <NUM>, the compressor section <NUM>, the turbine section <NUM>, etc.).

Referring back to <FIG>, the controller <NUM> can generally correspond to any suitable processor-based device, including one or more computing devices. For instance, <FIG> illustrates one embodiment of suitable components that can be included within the controller <NUM>. As shown in <FIG>, the controller <NUM> can include a processor <NUM> and associated memory <NUM> configured to perform a variety of computer-implemented functions. In various embodiments, the controller <NUM> may be configured to operate the actuator assembly <NUM> such as to provide a signal to the control valve <NUM> commanding supply or modulation of the pressure of the motive fluid to the input drive assembly <NUM>.

As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), a Field Programmable Gate Array (FPGA), and other programmable circuits. Additionally, the memory <NUM> can generally include memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., flash memory), a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements or combinations thereof. In various embodiments, the controller <NUM> may define one or more of a full authority digital engine controller (FADEC), a propeller control unit (PCU), an engine control unit (ECU), or an electronic engine control (EEC).

As shown, the controller <NUM> may include control logic <NUM> stored in memory <NUM>. The control logic <NUM> may include instructions that when executed by the one or more processors <NUM> cause the one or more processors <NUM> to perform operations such as rotating, extending, or retracting, or otherwise displacing the actuator assembly <NUM>.

Additionally, as shown in <FIG>, the controller <NUM> may also include a communications interface module <NUM>. In various embodiments, the communications interface module <NUM> can include associated electronic circuitry that is used to send and receive data. As such, the communications interface module <NUM> of the controller <NUM> can be used to receive data from the actuator assembly <NUM>, or from position sensors from vane assemblies attached thereto.

In addition, the communications interface module <NUM> can also be used to communicate with any other suitable components of the actuator assembly <NUM> or the apparatus <NUM>, such as to receive data or send commands to/from any number of valves, vane assemblies, hydraulic or pneumatic systems providing motive fluid, rotor assemblies, ports, etc. controlling speed, pressure, or flow at the apparatus <NUM> or actuator assembly <NUM> including the control valve assembly <NUM>.

It should be appreciated that the communications interface module <NUM> can be any combination of suitable wired and/or wireless communications interfaces and, thus, can be communicatively coupled to one or more components of the actuator assembly <NUM> via a wired and/or wireless connection. As such, the controller <NUM> may operate, modulate, or adjust operation of the actuator assembly <NUM>, and/or acquire or transmit signals via the actuator assembly <NUM> including the control valve <NUM>.

Claim 1:
A rotary actuator assembly (<NUM>), the rotary actuator assembly (<NUM>) comprising:
an output shaft (<NUM>);
an input drive assembly (<NUM>) including an input shaft (<NUM>), wherein the output shaft (<NUM>) is coupled to the input drive assembly (<NUM>); and
a piston assembly (<NUM>) comprising a body (<NUM>) surrounding a piston (<NUM>) moveable within the body (<NUM>), wherein the body (<NUM>) defines a first end (<NUM>) and a second end (<NUM>) opposite thereof between which the piston (<NUM>) is moveable within the body (<NUM>), and further wherein the piston assembly (<NUM>) includes a spring (<NUM>) disposed at the first end (<NUM>) between the body (<NUM>) and the piston (<NUM>), and wherein the piston assembly (<NUM>) comprises a friction mechanism (<NUM>) disposed at a second end of the piston (<NUM>) opposite of a first end of the piston (<NUM>), wherein the friction mechanism (<NUM>) is configured to engage the piston (<NUM>) to the input drive assembly (<NUM>), wherein an adjustable area (<NUM>) is defined within the body (<NUM>) between the second end of the piston (<NUM>) and the input drive assembly (<NUM>), and wherein the friction mechanism (<NUM>) comprises a serrated geometry at the piston (<NUM>) and the input shaft (<NUM>), wherein the serrated geometry is configured to statically couple together the piston (<NUM>) and the input drive assembly (<NUM>), characterized in that the body (<NUM>) defines a groove (<NUM>) extended laterally between the first end (<NUM>) and the second end (<NUM>), and wherein the piston (<NUM>) is at least partially disposed in the groove (<NUM>) to prevent rotation of the piston (<NUM>).