Patent Description:
Some aerial vehicles include a turboprop engine operatively coupled with a propeller for producing thrust. In some instances, fast acceleration of the turboprop engine can cause the speed of the propeller to overshoot the maximum propeller speed that can be demanded by a pilot, or the maximum demanded propeller speed. For instance, the propeller speed can overshoot the maximum demanded propeller speed during takeoff when the turboprop engine accelerates from an idle engine setting to a take-off power setting. In some cases, the propeller speed can overshoot the maximum demanded propeller speed such that the actual propeller speed reaches or nearly reaches a propeller speed maximum limit. There is typically safety margin between the propeller speed maximum limit and the maximum demanded propeller speed, and when the propeller speed overshoots the maximum demanded propeller speed, the margin can be breached to an unsatisfactory degree. Propeller speed overshoot can negatively affect the turboprop engine and/or propeller life and can limit the number of propellers that can be used with the turboprop engine as propeller speed overshoot can be a limiting factor during propeller selection. Propeller speed overshoot can have other drawbacks as well. <CIT> discloses an aircraft control system having a propellor speed governor including a stepper motor controllable to adjust the speed set point of the propellor based on the difference between the actual speed of the propellor and a desired speed determined from the throttle position.

Therefore, there is a need for an improved control system for an engine operatively coupled with a propeller and methods for controlling the same that address one or more of the challenges noted above.

In one aspect, the present subject matter is directed to a control system for an engine operatively coupled with a propeller as claimed in claim <NUM>.

In another aspect, the present subject matter is directed to a method for controlling an engine operatively coupled with a propeller as claimed in claim <NUM>.

In another aspect, the present subject matter is directed to a vehicle as claimed in claim <NUM>.

In yet another example aspect, a control system for a drive element operatively coupled with a rotating element is provided. The drive element can drive the rotating element about an axis of rotation. The drive element can be operatively coupled with the rotating element in any suitable manner, such as e.g., by one or more shafts or other mechanical linking members. The driving element can be an electric motor, an engine, a turbine, or some other suitable element for generating useful rotational work. The rotational element can be any suitable rotating element, such as e.g., a propeller, an impeller, blades of a wind turbine, vanes, etc. The control system includes a governor having a motor. Further, the control system includes a sensor operable to sense a rotational speed of the rotating element. Further, the control system includes one or more control devices communicatively coupled with the motor of the governor and the sensor. The one more control devices are configured to: receive, from the sensor, data indicative of the rotational speed of the rotating element; determine whether the rotational speed exceeds a rotational speed threshold; and cause the motor of the governor to adjust the rotational speed of the rotational element if the sensed rotational speed exceeds the rotational speed threshold.

In another example aspect, the present subject matter is directed to a method for controlling a system having a driving element operatively coupled with a rotating element. The method includes receiving, by one or more control devices, data indicative of a rotational speed of the rotating element. Further, the method includes determining, by the one or more control devices, whether the rotational speed exceeds a rotational speed threshold. Moreover, the method includes adjusting a rotational speed set point to change the rotational speed of the rotating element based at least in part on whether the rotational speed exceeds the rotational speed threshold.

Further, as used herein, the terms "axial" or "axially" refer to a dimension along a longitudinal axis of an engine. The term "forward" used in conjunction with "axial" or "axially" refers to a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term "aft" or "rear" used in conjunction with "axial" or "axially" refers to a direction toward the engine nozzle, or a component being relatively closer to the engine nozzle as compared to another component. The terms "radial" or "radially" refer to a dimension extending between a center longitudinal axis (or centerline) of the engine and an outer engine circumference. Radially inward is toward the longitudinal axis and radially outward is away from the longitudinal axis.

The subject matter of the present disclosure is directed generally to a control system for an engine operatively coupled with a propeller, and more particularly, to a control system for preventing propeller speed overshoot of a propeller operatively coupled with an engine. In one example aspect, the control system includes an electronic engine controller and an electric propeller governor. The electric propeller governor includes opposing flyweights operatively coupled with a pilot valve and a flyweight governor spring. Notably, the electric propeller governor includes a motor operatively coupled with the flyweight governor spring. The motor is communicatively coupled with the engine controller. The engine controller is operable to receive data indicative of the speed of the propeller, determine if the measured speed exceeds a propeller speed threshold, and if the threshold is exceeded, the engine controller is configured to change a propeller speed set point. Particularly, the engine controller can cause the motor to change the preload on the flyweight governor spring, which in turn causes adjustment of the propeller speed set point. For example, the propeller speed set point can be adjusted from a minimum demanded propeller speed or set point (Np Min) to a maximum demanded propeller speed or set point (Np Max) when the engine and propeller rapidly accelerate and the propeller speed exceeds the threshold. In this way, the speed of the propeller is prevented from overshooting the demanded propeller speed and is prevented from reaching or obtaining the maximum propeller speed limit (Np Max Limit). Accordingly, the engine and propeller are not subject to the negative impacts associated with propeller speed overshoot. A method for controlling an engine operatively coupled with a propeller is also provided.

<FIG> provides a schematic top plan view of a vehicle according to an example embodiment of the present subject matter. For this embodiment, the vehicle is a fixed-wing aerial vehicle <NUM>. In alternative embodiments, the aerial vehicle <NUM> can be other suitable types of aerial vehicles, such as a rotary aircraft, a vertical take-off and landing aircraft, a tiltrotor aircraft, an airship, an unmanned aerial vehicle, etc. Further, in some embodiments, the vehicle can be other types of vehicles having an engine and a propeller operatively coupled thereto, such as e.g., a marine vehicle or watercraft, a hovercraft, etc..

As depicted in <FIG>, the aerial vehicle <NUM> extends between a first end <NUM> and a second end <NUM>, e.g., along a longitudinal axis L. The first end <NUM> is a forward end of the aerial vehicle <NUM> and the second end <NUM> is a rear or aft end of the aerial vehicle <NUM> in the depicted embodiment of <FIG>. The aerial vehicle <NUM> includes a fuselage <NUM> and a pair of wings <NUM> each extending laterally outward from the fuselage <NUM>. The aerial vehicle <NUM> can include various control surfaces for controlling movement of the aerial vehicle <NUM>. Example control surfaces include elevators, rudders, ailerons, spoilers, flaps, slats, air brakes, or trim devices, etc. Various actuators, servo motors, and other devices can be used to manipulate the various control surfaces and variable geometry components of the aerial vehicle <NUM>.

The aerial vehicle <NUM> includes an engine <NUM> mounted to its forward end <NUM>. The engine <NUM> can be any suitable aeromechanical torque source. For instance, the engine <NUM> can be a gas turbine engine. For the depicted embodiment of <FIG>, the engine <NUM> is configured as a turboprop. However, in alternative embodiments, the engine <NUM> can be other suitable types of engines operatively coupled with a propeller. For instance, in some alternative embodiments, the engine <NUM> can be a piston-driven engine. Moreover, in some embodiments, the aerial vehicle <NUM> can include more than one engine. For example, in some embodiments, the aerial vehicle <NUM> can include at least one turboprop mounted to each wing <NUM>.

The aerial vehicle <NUM> also includes a propeller <NUM> operatively coupled with the engine <NUM>. For instance, the propeller <NUM> can be mechanically coupled, e.g., as shown in <FIG> and <FIG>. Generally, the propeller <NUM> is configured to produce thrust when driven by the engine <NUM>. The propeller <NUM> includes a plurality of propeller blades <NUM>. In some embodiments, the blades <NUM> of the propeller <NUM> are adjustable in unison through a plurality of blade pitch angles, e.g., by activation of an actuation mechanism. Pitch adjustment of the blades <NUM> can cause the propeller <NUM> to produce more or less thrust depending on the blade angle of the blades <NUM>.

<FIG> and <FIG> provide various views of the engine <NUM> of the aerial vehicle <NUM> of <FIG>. Particularly, <FIG> provides a side view of the engine <NUM> and <FIG> provides a perspective, cutaway view of the engine <NUM>. For reference, the gas turbine engine <NUM> defines an axial direction A, a radial direction R, and a circumferential direction C (<FIG>) extending three hundred sixty degrees (<NUM>°) around the axial direction A. The gas turbine engine <NUM> also defines a longitudinal or axial centerline <NUM> extending along the axial direction A. The gas turbine engine <NUM> extends generally along the axial direction A between a first end <NUM> and a second end <NUM>, which for this embodiment is the forward and aft end, respectively. Generally, the gas turbine engine <NUM> includes a gas generator or core turbine engine <NUM> that is operatively coupled with the propeller <NUM>. The propeller <NUM> and various components of the core turbine engine <NUM> are rotatable about the axial centerline <NUM>, or more generally, the axial direction A.

As shown best in <FIG>, the core turbine engine <NUM> generally includes, in serial flow arrangement, a compressor section <NUM>, a combustion section <NUM>, a turbine section <NUM>, and an exhaust section <NUM>. A core air flowpath <NUM> extends from an annular inlet <NUM> to one or more exhaust outlets <NUM> of the exhaust section <NUM> such that the compressor section <NUM>, combustion section <NUM>, turbine section <NUM>, and exhaust section <NUM> are in fluid communication.

The compressor section <NUM> can include one or more compressors, such as a high pressure compressor (HPC) and a low pressure compressor (LPC). For this embodiment, the compressor section <NUM> includes a four-stage axial, single centrifugal compressor. In particular, the compressor includes sequential stages of compressor stator vanes and rotor blades (not labeled), as well as an impeller (not labeled) positioned downstream of the axial stages of stator vanes and rotor blades. The combustion section <NUM> includes a reverse-flow combustor (not labeled) and one or more fuel nozzles (not shown). The turbine section <NUM> can define one or more turbines, such as a high pressure turbine (HPT) and a low pressure turbine (LPT). For this embodiment, the turbine section <NUM> includes a two-stage HPT <NUM> for driving the compressor of the compressor section <NUM>. The HPT <NUM> includes two sequential stages of stator vanes and turbine blades (not labeled). The turbine section <NUM> also includes a three-stage free or power turbine <NUM> that drives a propeller gearbox <NUM>, which in turn drives the propeller assembly <NUM> (<FIG>). The exhaust section <NUM> includes one or more exhaust outlets <NUM> for routing the combustion products to the ambient air.

Referring still to <FIG>, the core turbine engine <NUM> can include one or more shafts. For this embodiment, the gas turbine engine <NUM> includes a compressor shaft <NUM> and a free or power shaft <NUM>. The compressor shaft <NUM> drivingly couples the turbine section <NUM> with the compressor section <NUM> to drive the rotational components of the compressor. The power shaft <NUM> drivingly couples the power turbine <NUM> to drive a gear train <NUM> of the propeller gearbox <NUM>, which in turn operatively supplies power and torque to the propeller <NUM> (<FIG>) via a torque output or propeller shaft <NUM> at a reduced RPM. The forward end of the propeller shaft <NUM> includes a flange <NUM> that provides a mounting interface for the propeller assembly <NUM> to be attached to the core turbine engine <NUM>.

The propeller gearbox <NUM> is enclosed within a gearbox housing <NUM>. For this embodiment, the housing <NUM> encloses the epicyclical gear train <NUM> that includes a star gear <NUM> and a plurality of planet gears <NUM> disposed about the star gear <NUM>. The planetary gears <NUM> are configured to revolve around the star gear <NUM>. An annular gear <NUM> is positioned axially forward of the star and planetary gears <NUM>, <NUM>. As the planetary gears <NUM> rotate about the star gear <NUM>, torque and power are transmitted to the annular gear <NUM>. As shown, the annular gear <NUM> is operatively coupled to or otherwise integral with the propeller shaft <NUM>. In some embodiments, the gear train <NUM> may further include additional planetary gears disposed radially between the plurality of planet gears <NUM> and the star gear <NUM> or between the plurality of planet gears <NUM> and the annular gear <NUM>. In addition, the gear train <NUM> may further include additional annular gears.

As noted above, the core turbine engine <NUM> transmits power and torque to the propeller gearbox <NUM> via the power shaft <NUM>. The power shaft <NUM> drives the star gear <NUM>, which in turn drives the planetary gears <NUM> about the star gear <NUM>. The planetary gears <NUM> in turn drive the annular gear <NUM>, which is operatively coupled with the propeller shaft <NUM>. In this way, the energy extracted from the power turbine <NUM> supports operation of the propeller shaft <NUM>, and through the power gear train <NUM>, the relatively high RPM of the power shaft <NUM> is reduced to a more suitable RPM for the propeller <NUM>.

With reference to <FIG>, during operation of the gas turbine engine <NUM>, a volume of air indicated by arrow <NUM> passes across the plurality of propeller blades <NUM> circumferentially spaced apart from one another along the circumferential direction C and disposed about the axial direction A, and more particularly for this embodiment, the axial centerline <NUM>. The propeller assembly <NUM> includes a spinner <NUM> aerodynamically contoured to facilitate an airflow through the plurality of propeller blades <NUM>. The spinner <NUM> is rotatable with the propeller blades <NUM> about the axial direction A and encloses various components of the propeller assembly <NUM>, such as e.g., the hub, propeller pitch actuator, piston/cylinder actuation mechanisms, etc. A first portion of air indicated by arrow <NUM> is directed or routed outside of the core turbine engine <NUM> to provide propulsion. A second portion of air indicated by arrow <NUM> is directed or routed through the annular inlet <NUM> of the gas turbine engine <NUM>.

As shown in <FIG>, the second portion of air <NUM> enters through the annular inlet <NUM> and flows downstream to the compressor section <NUM>, which is a forward direction along the axial direction A in this embodiment. The second portion of air <NUM> is progressively compressed as it flows through the compressor section <NUM> downstream toward the combustion section <NUM>.

The compressed air indicated by arrow <NUM> flows into the combustion section <NUM> where fuel is introduced, mixed with at least a portion of the compressed air <NUM>, and ignited to form combustion gases <NUM>. The combustion gases <NUM> flow downstream into the turbine section <NUM>, causing rotary members of the turbine section <NUM> to rotate, which in turn supports operation of respectively coupled rotary members in the compressor section <NUM> and propeller assembly <NUM>. In particular, the HPT <NUM> extracts energy from the combustion gases <NUM>, causing the turbine blades to rotate. The rotation of the turbine blades of the HPT <NUM> causes the compressor shaft <NUM> to rotate, and as a result, the rotary components of the compressor are rotated about the axial direction A. In a similar fashion, the power turbine <NUM> extracts energy from the combustion gases <NUM>, which causes the blades of the power turbine <NUM> to rotate about the axial direction A. The rotation of the turbine blades of the power turbine <NUM> causes the power shaft <NUM> to rotate, which in turn drives the power gear train <NUM> of the propeller gearbox <NUM>.

The propeller gearbox <NUM> in turn transmits the power provided by the power shaft <NUM> to the propeller shaft <NUM> at a reduced RPM and desired amount of torque. The propeller shaft <NUM> in turn drives the propeller assembly <NUM> such that the propeller blades <NUM> rotate about the axial direction A, and more particularly for this embodiment, the axial centerline <NUM> of the gas turbine engine <NUM>. The exhaust gases, denoted by <NUM>, exit the core turbine engine <NUM> through the exhaust outlets <NUM> to the ambient air.

It should be appreciated that the example gas turbine engine <NUM> described herein is provided by way of example only. For example, in other example embodiments, the engine may include any suitable number or types of compressors, turbines, shafts, stages, etc. Additionally, in some example embodiments, the gas turbine engine may include any suitable type of combustor, and may not include the example reverse-flow combustor depicted. It will further be appreciated that the engine can be configured as any suitable type of engine operatively coupled with a propeller. For instance, in some embodiments, the engine can be configured as a reciprocating or piston engine. In addition, it will be appreciated that the present subject matter can be applied to or employed with any suitable type of propeller or fan configuration, including, for example, tractor and pusher configurations.

Returning to <FIG>, as shown, the aerial vehicle <NUM> of <FIG> is equipped with an electronic engine control system (EECS) <NUM>. As will be detailed herein, the control system <NUM> includes propeller speed overshoot preventing logic that, in conjunction with other features of the control system <NUM>, prevent or reduce propeller speed overshoot during fast acceleration or deceleration of the engine <NUM>. For instance, when the engine <NUM> accelerates from idle to full power during takeoff of the aerial vehicle <NUM>, the control system <NUM> prevents the speed of the propeller from overshooting the demanded maximum propeller speed. In this way, the life of the engine can be increased or extended. For instance, with use of the control system <NUM> described herein, propeller speed overshoot was decreased by two percent (<NUM>%), and consequently, the life of the engine can be increased by a minimum of fifteen percent (<NUM>%). Further, with use of the control system <NUM> described herein, the safety margin of the engine can be increased, the number of propellers that can be selected for use with the engine can be increased as propeller speed overshoot is typically a limiting factor for selecting a suitable propeller for the engine, a wider range for adjustment of the minimum flight pitch angle can be achieved, and a wider range for adjustment of the maximum propeller speed can be achieved due to the greater margin between the maximum propeller speed and minimum propeller speed, among other benefits and advantages.

<FIG> graphically depicts the advantages of the control system <NUM> of the present disclosure. Particularly, the graph of <FIG> depicts the propeller speed of a propeller operatively coupled with an engine controlled by the control system <NUM> of the present disclosure (labeled as Np1) versus time and the propeller speed of a propeller operatively coupled with an engine controlled by a conventional control system (labeled as Np2) versus time. As shown, during fast acceleration of the engine, the propeller speed Np2 of the propeller controlled by the conventional control system (i.e., a control system without overshoot preventing logic) accelerates rapidly from under <NUM>,<NUM> rpm to about <NUM>,<NUM> rpm in about five seconds (<NUM>). Notably, the propeller speed Np2 overshoots the maximum demanded propeller speed (labeled as Np Max) set at <NUM>,<NUM> rpm and increases to about the propeller speed maximum limit (labeled as Np Max Limit), which is <NUM>,<NUM> rpm in this example (<NUM>% of Np Max). The propeller speed Np2 eventually settles within a predetermined range of steady state (e.g., within plus or minus five percent (<NUM>%) of a steady state value) at about <NUM>,<NUM> rpm after about ten seconds (<NUM>). As noted above, overshooting the maximum demanded propeller speed (Np Max) can negatively affect the life of the engine and/or the propeller in a significant way and can limit the selection of propellers available for use with the engine, among other drawbacks. Overshooting the maximum demanded propeller speed (Np Max) and reaching or obtaining the propeller speed maximum limit (Np Max Limit) on the first overshoot as shown in <FIG> especially impacts the life cycle of the engine and propeller.

In comparison, during fast acceleration of the engine, the propeller speed Np1 of the propeller controlled by the control system <NUM> accelerates rapidly from under <NUM>,<NUM> rpm to about <NUM>,<NUM> rpm in about five seconds (<NUM>). Advantageously, as depicted, during rapid acceleration of the engine, the propeller speed Np <NUM> rapidly accelerates and has a very minimal, if any, overshoot of the maximum demanded propeller speed (Np Max), which is <NUM> rpm in this example as noted above. The propeller speed Np1 eventually settles within a predetermined range of steady state (e.g., within plus or minus five percent (<NUM>%) of a steady state value) at about <NUM>,<NUM> rpm after about ten seconds (<NUM>). Accordingly, as the propeller speed Np1 does not or only minimally overshoots the maximum demanded propeller speed (Np Max), the engine and propeller are not negatively impacted in the same manner as the propeller controlled by the conventional control system. The control system <NUM> that prevents propeller speed overshoot and provides the advantages and benefits described above will be described in detail below.

<FIG> provides a schematic view of control system <NUM> according to an example embodiment of the present subject matter. The control system <NUM> can be an electronic engine control system (EECS), for example. As shown, the control system <NUM> can include one or more control devices for controlling the engine <NUM> and the propeller <NUM>. Particularly, for the depicted embodiment of <FIG>, the one or more control devices include an electronic engine controller (EEC) <NUM> configured to control the gas turbine engine <NUM> and the propeller <NUM>. The controller <NUM> can operate as the central control unit for the control system <NUM>, which as noted above, can be an EECS. In some embodiments, the controller <NUM> can be an analog electronic box. In other embodiments, the controller <NUM> can be a computing device.

Further, in some alternative embodiments, the control system <NUM> can be a Full Authority Digital Engine and Propeller Control (FADEPC) system operable to provide full digital control of the core turbine engine <NUM> of the gas turbine engine <NUM> and the propeller <NUM>. The controller <NUM> can operate as the central control unit of the FADEC system. In yet other embodiments, the one or more control devices of the control system <NUM> can include more than one controller for controlling the core turbine engine <NUM> and the propeller <NUM>. For example, in some example embodiments, the control system <NUM> can include an EEC equipped with Full Authority Digital Engine Control (FADEC) and a propeller controller equipped with Full Authority Digital Propeller Control (FADPC). In such embodiments, the EEC and the propeller controller are communicatively coupled, e.g., via a suitable wired or wireless communication link.

The controller <NUM> depicted in the illustrated embodiment of <FIG> can control various aspects of the core turbine engine <NUM> and the propeller <NUM> as noted above. For instance, for this embodiment, the controller <NUM> includes propeller speed overshoot preventing logic <NUM> that, in conjunction with other features of the control system <NUM>, reduce the propeller speed overshoot during fast acceleration or deceleration of the engine <NUM>. The propeller speed overshoot preventing logic <NUM> includes propeller speed selector logic <NUM> (denoted as Np selector logic <NUM> in <FIG>) and a motor drive <NUM> operable to drive a motor (e.g., a stepper motor) as will be explained below.

Moreover, the controller <NUM> can be communicatively coupled with various sensors. For instance, as shown in <FIG>, the controller <NUM> is communicatively coupled with a sensor <NUM>, e.g., via a wired or wireless communication link. For this embodiment, the sensor <NUM> is a propeller speed sensor operable to sense the speed of the propeller <NUM> as it rotates about its axis of rotation. The controller <NUM> can receive the data indicative of the propeller speed from the sensor <NUM>. In some control schemes, the data can be routed to the propeller speed overshoot preventing logic <NUM> so that the engine <NUM> and the propeller <NUM> can be controlled based at least in part on the measured propeller speed.

The control system <NUM> also includes a fuel metering unit (FMU) <NUM> for metering fuel to the engine <NUM>, e.g., from a fuel tank onboard the aerial vehicle <NUM> (<FIG>). The fuel metering unit <NUM> is communicatively coupled with the controller <NUM>, e.g., via a suitable wired or wireless communication link. The controller <NUM> can control the FMU <NUM> to selectively allow a volume of fuel to engine <NUM>, e.g., based on an engine speed set point and/or other control aspects.

Further, the control system <NUM> includes an electric propeller governor <NUM>. The electric propeller governor <NUM> can be mounted to the engine <NUM>, e.g., within or to housing <NUM> (<FIG>). Generally, the electric propeller governor <NUM> is operable to control or govern the speed of the propeller <NUM>. The electric propeller governor <NUM> can be any suitable hydromechanical propeller governor. For instance, the electric propeller governor <NUM> can be a constant speed propeller governor operable to respond to a change in engine speed by directing oil under pressure to a propeller hydraulic cylinder or by releasing oil from the hydraulic cylinder, e.g., to move a piston disposed within the cylinder, to ultimately change the pitch angle of the propeller blades <NUM> (<FIG>) of the propeller <NUM> such that the engine speed can be maintained at a set engine speed. The electric propeller governor <NUM> can be set to a specific speed set point (rpm) via a propeller speed selector device <NUM>. The selector device <NUM> can be any suitable device operable to switch or adjust the speed of the propeller <NUM>. For instance, the selector device <NUM> can be a switch located in a cockpit of the aircraft to which the engine <NUM> and propeller <NUM> are mounted. In other embodiments, the selector device <NUM> can be a lever or some other manually adjustable device.

<FIG> provides a schematic view of the electric propeller governor <NUM> according to an example embodiment of the present subject matter. As depicted, the electric propeller governor <NUM> includes a pilot valve <NUM> controlled by flyweights <NUM> to control the flow of oil (not shown) to or from a propeller pitch control unit (not shown) of the propeller <NUM>, which ultimately increases or decreases the propeller speed by changing the pitch of the propeller blades <NUM>. The electric propeller governor <NUM> includes a flyweight governor spring <NUM>, also referred to as a speeder spring, that is mechanically coupled with a spring adjustment mechanism <NUM> (e.g., a vertical adjusting worm or other suitable adjustment mechanism), which is in turn mechanically coupled with a motor as explained below. The flyweight governor spring <NUM> opposes the ability of the flyweights <NUM> to move outward from the flyweight governor spring <NUM>. The preload (e.g., tension or compression) on the flyweight governor spring <NUM> can be adjusted manually by user manipulation of the selector device <NUM> (located within the cockpit of the aerial vehicle <NUM> (<FIG>)), in response to movement of the flyweights <NUM> to maintain an onspeed condition, or automatically via control system <NUM> as will be explained herein. The preload on the flyweight governor spring <NUM> ultimately controls the speed of the engine <NUM>.

Generally, the electric propeller governor <NUM> can operate in an onspeed condition, an overspeed condition, and an underspeed condition. When the engine <NUM> is operating above the engine speed set point, the electric propeller governor <NUM> operates in an overspeed condition. When this occurs, the flyweights <NUM> overcome the tension of the flyweight governor spring <NUM> and move outward from the flyweight governor spring <NUM>, e.g., as shown in <FIG>. The outward movement of the flyweights <NUM> moves the pilot valve <NUM> (e.g., vertically upward) to move oil to or from the propeller pitch control unit (not shown) so that the pitch of the blades <NUM> can be increased. The increased pitch of the blades <NUM> increases the load on the engine <NUM>, and consequently, the engine speed decreases so that the set speed of the engine is maintained. On the other hand, when the engine <NUM> is operating below the engine speed set point, the electric propeller governor <NUM> operates in an underspeed condition. When this occurs, the flyweights <NUM> move or tilt inward due to the lack of centrifugal force on the flyweights <NUM> to overcome the force of the flyweight governor spring <NUM>. The pilot valve <NUM> is moved by the flyweight governor spring <NUM> (e.g., vertically downward) and the pilot valve <NUM> meters oil flow to the propeller pitch control unit so that the pitch of the blades <NUM> can be decreased, which consequently raises the speed of the engine <NUM>. Oil can be metered to and from the propeller pitch control unit until an onspeed condition is met, e.g., when the force on the flyweights <NUM> and the tension on the flyweight governor spring <NUM> are balanced, or stated alternatively, when the speed of the engine matches the engine speed set by the pilot. The balance of forces can be disturbed by the aircraft changing attitude (climb or dive), the pilot changing the tension on the flyweight governor spring <NUM> utilizing the selector device <NUM> (e.g., by user manipulation of a switch), or automatically by control system <NUM> if certain conditions are met during rapid acceleration or deceleration of the engine <NUM>.

With reference now to <FIG> and <FIG>, as shown, the electric propeller governor <NUM> includes a motor <NUM> mechanically coupled with the flyweight governor spring <NUM>. For instance, the output shaft <NUM> of the motor <NUM> can be mechanically coupled with the flyweight governor spring <NUM> via spring adjustment mechanism <NUM> as shown in <FIG>. The motor <NUM> can be a stepper motor, for example. When certain conditions are met during rapid acceleration or deceleration of the engine <NUM>, the controller <NUM> can cause the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM>, e.g., by applying a torque on spring adjustment mechanism <NUM> via output shaft <NUM>, which in turns adjusts the tension of flyweight governor spring <NUM>. More particularly, if certain conditions are met during rapid acceleration or deceleration of the engine <NUM>, the motor drive <NUM> of the controller <NUM> can send one or more command signals <NUM> (e.g., one or more pulses) to the motor <NUM> such that the output shaft <NUM> of the motor <NUM> is rotated the desired number of steps. In this way, the motor <NUM> can accurately and precisely control the preload on the flyweight governor spring <NUM>. In other example embodiments, the motor <NUM> can be mechanically coupled with the flyweight governor spring <NUM> in other example manners. Further, the selector device <NUM> can be communicatively coupled (e.g., electrically connected) with the motor <NUM>. For instance, as shown best in <FIG>, the selector device <NUM> can be directly electrically connected with the propeller speed selector logic <NUM> of controller <NUM>, which is electrically connected with and controls the motor drive <NUM>, which in turn is electrically connected with and controls the motor <NUM>. In this way, a pilot can manipulate the selector device <NUM> within the cockpit, and in turn, the motor <NUM> can turn its output shaft <NUM> to ultimately change the preload on the flyweight governor spring <NUM>. Thus, the pilot can use the selector device <NUM> to change or adjust the propeller speed via selector device <NUM>. In yet other embodiments, the selector device <NUM> can be mechanically coupled (e.g., one or more linkages) to spring adjustment mechanism <NUM>, and in such embodiments, manual manipulation of selector device <NUM> (e.g., a lever) can cause adjustment of the preload on flyweight governor spring <NUM>.

With reference now to <FIG>, <FIG>, an example manner in which the control system <NUM> can reduce or prevent propeller speed overshoot is provided. <FIG> provides a graph depicting propeller speed of the propeller <NUM> operatively coupled with the engine <NUM> versus time and <FIG> provides a graph that corresponds with the graph of <FIG> and depicts the angle of a single power control lever (SPCL), which is representative of the demanded engine power, versus time.

During operation of the engine <NUM>, or more particularly the engine <NUM> and propeller <NUM> operatively coupled thereto, the controller <NUM> receives data <NUM> (<FIG>) indicative of the propeller speed (denoted as "Np" in <FIG>) of the propeller <NUM>. The controller <NUM> can receive the data <NUM> from the sensor <NUM> communicatively coupled thereto, e.g., via a wired or wireless communication link. The controller <NUM> can continuously receive data <NUM> during operation of the engine <NUM> or can receive data <NUM> at predetermined intervals, e.g., every ten milliseconds (<NUM>). In this way, the speed of the propeller <NUM> can continuously or nearly continuously be monitored during operation of the engine <NUM>. Once the controller <NUM> receives the data <NUM> indicative of the propeller speed of the propeller <NUM>, the controller <NUM> is configured to determine whether the measured propeller speed exceeds a propeller speed threshold.

For instance, when the SPCL (<FIG>) is moved from an angle of zero degrees (<NUM>°) to an angle of about thirty-three degrees (<NUM>°) as shown in <FIG>, the engine <NUM> (<FIG>) accelerates rapidly from idle to full power, and consequently, the propeller speed of the propeller <NUM> rapidly accelerates as well as shown in <FIG>. Particularly, as depicted in <FIG>, the propeller speed Np of the propeller <NUM> accelerates from under <NUM>,<NUM> rpm to about <NUM>,<NUM> rpm in about five seconds (<NUM>). For this embodiment, the propeller speed threshold is set at <NUM>,<NUM> rpm as shown in <FIG>. As the propeller speed is accelerating (i.e., increasing in speed over time), the propeller speed threshold is an acceleration propeller speed threshold. The propeller speed overshoot preventing logic <NUM> of the controller <NUM> can determine whether the measured propeller speed (as determined from the data <NUM>) exceeds the propeller speed threshold. As shown in <FIG>, for this embodiment, the propeller speed Np of the propeller <NUM> exceeds the acceleration propeller speed threshold of <NUM>,<NUM> rpm at about four seconds (<NUM>).

As depicted in <FIG>, the propeller can be set at different propeller speed set points, e.g., a first set point and a second set point. The set point of the propeller speed corresponds to a demanded propeller speed (Np demanded). The first set point can correspond to a minimum propeller speed demanded (Np Min) and the second set point can correspond to a maximum propeller speed demanded (Np Max). In some embodiments, the propeller speed set point of the propeller <NUM> is only switchable between a first set point and a second set point. For instance, for this embodiment, the propeller speed set point of the propeller <NUM> is only switchable between a minimum propeller speed demanded (Np Min) and a maximum propeller speed demanded (Np Max). Stated differently, the pilot can demand either a minimum propeller speed (Np Min) or a maximum propeller speed (Np Max).

Notably, the controller <NUM> is configured to adjust the propeller speed set point to change the propeller speed of the propeller based at least in part on whether the propeller speed exceeds the propeller speed threshold. For instance, if the propeller speed exceeds the propeller speed threshold, e.g., as shown in <FIG> at about four seconds (<NUM>), then the propeller speed set point (i.e., Np demanded) is adjusted from Np Min to Np Max. For instance, as depicted in <FIG>, when the propeller speed exceeds the acceleration propeller speed threshold of <NUM>,<NUM> rpm, the propeller speed selector logic <NUM> of the propeller speed overshoot preventing logic <NUM> adjusts the propeller speed set point from Np Min to Np Max.

For this embodiment, to adjust the propeller speed set point, the controller <NUM> causes the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM> based at least in part on whether the propeller speed exceeds the acceleration propeller speed threshold. That is, the controller <NUM> causes the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM> if the measured propeller speed exceeds the acceleration propeller speed threshold. For instance, the motor drive <NUM> of the controller <NUM> can cause the stepper motor <NUM> to change the preload on the flyweight governor spring <NUM> if the propeller speed exceeds the propeller speed threshold. The motor drive <NUM> can command the motor <NUM> such that the motor <NUM> gradually or linearly changes the preload on the flyweight spring <NUM> at predefined rate of set point change, e.g., as shown in <FIG>. In <FIG>, the motor drive <NUM> commands the motor <NUM> to gradually change the preload on the flyweight spring <NUM> over the course of about two and a half seconds from four seconds (<NUM>) to about six and on a half seconds (<NUM>). The gradual or linear change of the preload on the flyweight governor spring <NUM> prevents vibration and jarring of the components of the propeller <NUM> and engine <NUM> during engine acceleration. The drive motor <NUM> can cause the motor <NUM> to drive its output shaft <NUM> (<FIG>) such that the output shaft <NUM> applies a torque on the spring adjustment mechanism <NUM> (<FIG>), which in turn can adjust the tension or preload on the flyweight governor spring <NUM>.

Notably, changing the preload on the flyweight governor spring <NUM> adjusts the propeller speed set point of the propeller <NUM>, or in this embodiment, the preload of the flyweight governor spring <NUM> adjusts the propeller speed set point of the propeller <NUM> from Np Min to Np Max as shown in <FIG>. By adjusting the propeller speed set point during fast acceleration as described above, advantageously, the propeller speed is prevented from overshooting the demanded propeller speed, or Np Max in this example. Rather, as depicted in <FIG>, the propeller speed reaches the demanded propeller speed or Np Max (<NUM>,<NUM> rpm in this example) and then stabilizes after several seconds. The propeller speed does not overshoot Np Max and consequently does not reach at or near the propeller speed maximum limit, or Np Max Limit. Accordingly, as shown, the control system <NUM> prevents the propeller speed from overshooting Np Max and thus the engine <NUM> and/or propeller <NUM> are not impacted by the drawbacks associated with overshooting the maximum demanded propeller speed and prevents the propeller speed from reaching at or near the propeller speed maximum limit (Np Max Limit), e.g., as shown by Np2 in <FIG> that is controlled by a conventional control system.

As further shown in <FIG>, the propeller speed threshold can also correspond to a deceleration propeller speed threshold if the propeller speed is decelerating (i.e., decreasing in speed over time). For instance, when the SPCL (<FIG>) is moved from an angle of about thirty-three degrees (<NUM>°) to an angle of zero degrees (<NUM>°) as shown in <FIG> at about fifteen seconds (<NUM>), the engine <NUM> (<FIG>) decelerates rapidly from full power to idle power, and consequently, the propeller speed of the propeller <NUM> rapidly decelerates as well as shown in <FIG>. Particularly, as depicted in <FIG>, the propeller speed of the propeller <NUM> decelerates from about <NUM>,<NUM> rpm to under <NUM>,<NUM> rpm in about ten seconds (<NUM>). For this embodiment, the deceleration propeller speed threshold is set at <NUM>,<NUM> rpm as shown in <FIG>. The propeller speed overshoot preventing logic <NUM> of the controller <NUM> can determine whether the measured propeller speed (as determined from the data <NUM>) exceeds the deceleration propeller speed threshold. As shown in <FIG>, for this embodiment, the propeller speed of the propeller <NUM> exceeds the deceleration propeller speed threshold of <NUM>,<NUM> rpm at about nineteen seconds (<NUM>).

The controller <NUM> is configured to adjust the propeller speed set point to change the propeller speed of the propeller based at least in part on whether the propeller speed exceeds the propeller speed threshold. For instance, if the propeller speed exceeds the deceleration propeller speed threshold, e.g., as shown in <FIG> at about nineteen seconds (<NUM>), then the propeller speed set point (i.e., the demanded propeller speed) is adjusted from Np Max to Np Min. As depicted in <FIG>, when the propeller speed exceeds the deceleration propeller speed threshold of <NUM>,<NUM> rpm, the propeller speed selector logic <NUM> adjusts the propeller speed set point from Np Max to Np Min.

For this embodiment, to adjust the propeller speed set point, the controller <NUM> causes the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM> based at least in part on whether the propeller speed exceeds the deceleration propeller speed threshold. That is, the controller <NUM> causes the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM> if the measured propeller speed exceeds the deceleration propeller speed threshold. For instance, the motor drive <NUM> of the controller <NUM> can cause the stepper motor <NUM> to change the preload on the flyweight governor spring <NUM> if the propeller speed exceeds the deceleration propeller speed threshold. The motor drive <NUM> can command the motor <NUM> such that the motor <NUM> gradually or linearly changes the preload on the flyweight spring <NUM>, e.g., as shown in <FIG>. In <FIG>, the motor drive <NUM> commands the motor <NUM> to gradually or linearly change the preload on the flyweight spring <NUM> over a predetermined time, or over the course of about two seconds from nineteen seconds (<NUM>) to about twenty-one seconds (<NUM>) in this example. The drive motor <NUM> can cause the motor <NUM> to drive its output shaft <NUM> (<FIG>) such that the output shaft <NUM> applies a torque on the spring adjustment mechanism <NUM> (<FIG>), which in turn can adjust the tension or preload on the flyweight governor spring <NUM>. Changing the preload on the flyweight governor spring <NUM> adjusts the propeller speed set point of the propeller <NUM>, or in this embodiment, the preload on the flyweight governor spring <NUM> adjusts the propeller speed set point of the propeller <NUM> from Np Max to Np Min as shown in <FIG>.

As shown best in <FIG>, the deceleration propeller speed threshold can be offset from the acceleration propeller speed threshold. Particularly, for this embodiment, the acceleration threshold (<NUM>,<NUM> rpm) and the deceleration (<NUM>,<NUM> rpm) threshold are offset by <NUM> rpm. In this manner, hysteresis is utilized to prevent undesired switching between Np Max and Np Min, e.g., caused by tolerances and control accuracies. For this embodiment, the acceleration propeller speed threshold is set at a higher rpm than the deceleration propeller speed threshold.

Further, in some embodiments, in addition to the propeller speed exceeding either the accelerating or decelerating propeller speed threshold, the speed of the propeller must also be accelerating or decelerating at a predetermined rate in order for the control system <NUM> to switch the propeller speed set point, e.g., from Np Min to Np Max or vice versa. For instance, in some embodiments, the controller <NUM> is configured to determine whether the propeller speed is changing at a predetermined rate (i.e., whether the propeller speed is accelerating or decelerating at a predetermined rate) based at least in part on the received data indicative of the propeller speed of the propeller. In such embodiments, if the propeller speed is changing at the predetermined rate and the propeller speed exceeds the propeller speed threshold, then the controller <NUM> is configured to automatically cause the motor <NUM> of the electric propeller governor <NUM> to change the preload on the flyweight governor spring <NUM>. As a result, the controller <NUM> automatically changes the propeller speed set point (e.g., from Np Min to Np Max or from Np Max to Np Min).

The predetermined rate can correspond to an acceleration predetermined rate or a deceleration predetermined rate depending on whether the propeller speed is increasing or decreasing. For instance, the acceleration predetermined rate can be set to correspond with acceleration of the propeller speed during takeoff of the vehicle <NUM> (<FIG>) as shown in <FIG>. For example, the acceleration predetermined rate can correspond to a rate of <NUM> rpm over a period of eight seconds (<NUM>). Thus, if the propeller speed increases by or more than <NUM> rpm over a period of eight seconds (<NUM>), as it does in <FIG>, the controller <NUM> can determine that the propeller speed exceeds the acceleration propeller speed threshold and is accelerating at the predetermined rate, and accordingly, the controller <NUM> can automatically cause adjustment of the propeller speed set point, e.g., from Np Min to Np Max. Further, in some embodiments, the deceleration predetermined rate can be set to correspond with deceleration of the propeller speed during a power down of the engine <NUM> as shown in <FIG>. For instance, the deceleration predetermined rate can correspond to a rate of <NUM> rpm over a period of ten seconds (<NUM>), for example. Thus, if the propeller speed decreases by or more than <NUM> rpm over a period of ten seconds (<NUM>), as it does in <FIG>, the controller <NUM> can determine that the propeller speed exceeds the deceleration propeller speed threshold and is decelerating at the deceleration predetermined rate, and accordingly, the controller <NUM> can automatically cause adjustment of the propeller speed set point, e.g., from Np Max to Np Min.

<FIG> provides a flow diagram of an example method (<NUM>) for controlling an engine operatively coupled with a propeller. For instance, the method (<NUM>) can be implemented to control the engine <NUM> and/or propeller <NUM> of the vehicle <NUM> of <FIG>. However, the method (<NUM>) can be implemented to control other engines operatively coupled with a propeller. Some or all of the method (<NUM>) can be implemented by control system <NUM> disclosed herein. In addition, it will be appreciated that exemplary method (<NUM>) can be modified, adapted, expanded, rearranged and/or omitted in various ways without deviating from the scope of the present subject matter.

At (<NUM>), the method (<NUM>) includes receiving, by one or more computing devices, data indicative of a propeller speed of the propeller. For instance, with reference to <FIG>, the controller <NUM> of the control system <NUM> can receive data <NUM> indicative of the speed of the propeller <NUM> from the sensor <NUM>. In some implementations, the controller <NUM> can receive data <NUM> continuously during operation of the engine <NUM> and propeller <NUM>. The data <NUM> can be routed from sensor <NUM> to controller <NUM> the any suitable wired and/or wireless communication link. The data <NUM> can be analog and/or digital signals. The data <NUM> indicative of the speed of the propeller <NUM> can be utilized by controller <NUM> to control the propeller speed set point of the propeller <NUM> and can also be used to determine the acceleration or deceleration of the propeller <NUM>.

At (<NUM>), the method (<NUM>) includes determining, by the one or more computing devices, whether the propeller speed exceeds a propeller speed threshold. For instance, with reference to <FIG>, once the controller <NUM> receives the data <NUM> indicative of the propeller speed of the propeller <NUM>, the controller <NUM> can determine whether the propeller speed exceeds a propeller speed threshold. In some implementations, the method (<NUM>) further includes determining, by the one or more computing devices, whether the propeller speed of the propeller is increasing or decreasing based at least in part on the received data indicative of the propeller speed of the propeller. In such implementations, if the propeller speed of the propeller is increasing over time (i.e., the propeller is accelerating), then the propeller speed threshold is an acceleration propeller speed threshold. Accordingly, the controller <NUM> determines whether the measured speed of the propeller <NUM> exceeds the acceleration propeller speed threshold. That is, the controller <NUM> determines whether the measured propeller speed is greater than the acceleration propeller speed threshold. For example, if the acceleration propeller speed threshold is set at <NUM>,<NUM> rpm (e.g., as shown in <FIG>), the controller <NUM> determines whether the measured propeller speed is greater than <NUM>,<NUM> rpm.

If, on the other hand, the propeller speed of the propeller is decreasing over time (i.e., the propeller is decelerating), then the propeller speed threshold is a deceleration propeller speed threshold. Accordingly, the controller <NUM> determines whether the measured speed of the propeller <NUM> exceeds the deceleration propeller speed threshold. That is, the controller <NUM> determines whether the measured propeller speed is less than the deceleration propeller speed threshold. For example, if the deceleration propeller speed threshold is set at <NUM>,<NUM> rpm (e.g., as shown in <FIG>), the controller <NUM> determines whether the measured propeller speed is less than <NUM>,<NUM> rpm. Notably, in some implementations, the deceleration propeller speed threshold and the acceleration propeller speed threshold are offset from one another. In this way, inadvertent or undesirable switching between propeller speed set points is prevented.

At (<NUM>), the method (<NUM>) includes adjusting a propeller speed set point to change the propeller speed of the propeller based at least in part on whether the propeller speed exceeds the propeller speed threshold. For instance, if the measured propeller speed exceeds the propeller speed threshold as determined at (<NUM>), then at (<NUM>) the propeller speed set point can be adjusted. In some implementations, the propeller speed set point is automatically adjusted to adjust propeller speed of the propeller if the propeller speed exceeds a propeller speed threshold.

In some implementations, the propeller speed set point is adjustable between a maximum set point (Np Max) and a minimum set point (Np Min). In some implementations, the propeller speed set point is adjustable only between the maximum set point (Np Max) and the minimum set point (Np Min). In such implementations, if the propeller speed of the propeller is increasing and the propeller speed of the propeller exceeds the acceleration propeller speed threshold, then the propeller speed set point is adjusted from the minimum set point (Np Min) to the maximum set point (Np Max). For example, with reference to <FIG>, the propeller speed is shown rapidly increasing from about one and a half seconds (<NUM>) to about four and a half seconds (<NUM>), and as depicted, the propeller speed exceeds the acceleration propeller speed threshold of <NUM>,<NUM> rpm at about four seconds (<NUM>). Accordingly, the propeller speed set point or demanded propeller speed is adjusted from the minimum set point (Np Min) to the maximum set point (Np Max). The control system <NUM> can automatically switch or adjust the propeller speed set point when the propeller speed exceeds the acceleration propeller speed set point. By adjusting the propeller speed set point from Np Min to Np Max during fast acceleration of the engine <NUM> and propeller <NUM>, the propeller speed is prevented from overshooting the demanded propeller speed (Np Max) and does not reach or obtain the maximum propeller speed limit (Np Max Limit); thus, the propeller <NUM> and engine <NUM> are not subject to the negative impacts associated with propeller speed overshoot.

If, on the other hand, the propeller speed of the propeller is decreasing and the propeller speed of the propeller exceeds the deceleration propeller speed threshold, then the propeller speed set point is adjusted from the maximum set point (Np Max) to the minimum set point (Np Min). For example, with reference to <FIG>, the propeller speed is shown rapidly decreasing at about fifteen seconds (<NUM>). As depicted, the propeller speed exceeds the deceleration propeller speed threshold of <NUM>,<NUM> rpm at about nineteen seconds (<NUM>). Thus, the propeller speed set point or demanded propeller speed is adjusted from the maximum set point (Np Max) to the minimum set point (Np Min). Notably, the control system <NUM> can automatically switch or adjust the propeller speed set point when the propeller speed exceeds the deceleration propeller speed set point.

In some implementations, adjusting the propeller speed set point based at least in part on whether the propeller speed exceeds the propeller speed threshold at (<NUM>) includes causing, by the one or more computing devices, a motor mechanically coupled with a flyweight governor spring of an electric propeller governor to change a preload on the flyweight governor spring. For instance, with reference to <FIG> and <FIG>, once the controller <NUM> determines that the measured propeller speed exceeds the propeller speed threshold at (<NUM>), the motor drive <NUM> of the controller <NUM> can command or pulse the motor <NUM>. When the motor <NUM> is pulsed, the output shaft <NUM> of the motor <NUM> is rotated or otherwise move about its axis of rotation, which applies a torque on the spring adjustment mechanism <NUM>. When the torque is applied on the spring adjustment mechanism <NUM>, the preload on the flyweight governor spring <NUM> is changed. That is, the spring adjustment mechanism <NUM> changes the tension on the flyweight governor spring <NUM>. The adjustment of the preload on the flyweight governor spring <NUM> adjusts the propeller speed set point, e.g., from Np Min to Np Max or vice versa depending on whether the propeller speed is accelerating or decelerating.

In some further implementations, causing, by the one or more computing devices, the motor mechanically coupled with the flyweight governor spring of the electric propeller governor to change the preload on the flyweight governor spring includes commanding, by a motor drive of the one or more computing devices communicatively coupled with the motor, the motor to change the preload on the flyweight governor spring such that the propeller speed set point linearly changes from a first set point to a second set point (e.g., from Np Min to Np Max or vice versa). For instance, as shown in <FIG>, when the propeller speed exceeds the acceleration propeller speed threshold at about four seconds (<NUM>), the motor drive <NUM> (<FIG>) commands the motor <NUM> (<FIG>) to change the preload on the flyweight governor spring <NUM> (<FIG>) such that the propeller speed set point linearly changes from Np Min to Np Max. This gradual or linear change smooths or eases the propeller into the higher demanded speed, or Np Max. As further depicted in <FIG>, when the propeller speed exceeds the deceleration propeller speed threshold at about nineteen seconds (<NUM>), the motor drive <NUM> (<FIG>) commands the motor <NUM> (<FIG>) to change the preload on the flyweight governor spring <NUM> (<FIG>) such that the propeller speed set point linearly changes from Np Max to Np Min. This gradual or linear change smooths or eases the propeller into the lower demanded speed, or Np Min and prevents jarring of the engine <NUM> and the propeller <NUM> operatively coupled thereto.

<FIG> provides an example computing system <NUM> according to example embodiments of the present subject matter. The computing system <NUM> can include one or more computing device(s) <NUM>. For instance, one of the computing device(s) <NUM> can be the controller <NUM> described herein. The computing device(s) <NUM> can include one or more processor(s) 510A and one or more memory device(s) 510B. The one or more processor(s) 510A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) 510B can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) 510B can store information accessible by the one or more processor(s) 510A, including computer-readable instructions 510C that can be executed by the one or more processor(s) 510A. The instructions 510C can be any set of instructions that when executed by the one or more processor(s) 510A, cause the one or more processor(s) 510A to perform operations. In some embodiments, the instructions 510C can be executed by the one or more processor(s) 510A to cause the one or more processor(s) 510A to perform operations, such as any of the operations and functions for which the computing system <NUM> and/or the computing device(s) <NUM> are configured, such as e.g., operations for controlling the engine <NUM> (<FIG>) and/or propeller <NUM> (<FIG>) as described herein. Thus, the method (<NUM>) can be implemented at least in part by the one or more computing device(s) <NUM> of the computing system <NUM>. The instructions 510C can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions 510C can be executed in logically and/or virtually separate threads on processor(s) 510A. The memory device(s) 510B can further store data 510D that can be accessed by the processor(s) 510A. For example, the data 510D can include data indicative of the various propeller speed thresholds, among other potential items or settings described herein.

The computing device(s) <NUM> can also include a network interface 510E used to communicate, for example, with the other components of system <NUM> (e.g., via a network). The network interface 510E can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, and/or other suitable components. One or more external devices, such as an external remote control, can be configured to receive one or more commands from the computing device(s) <NUM> or provide one or more commands to the computing device(s) <NUM>.

It will be appreciated that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

Claim 1:
A control system (<NUM>) for an engine (<NUM>) operatively coupled with a propeller (<NUM>), the control system (<NUM>) comprising:
an electric propeller governor (<NUM>) having a motor (<NUM>) and a flyweight governor spring (<NUM>) mechanically coupled with the motor (<NUM>), wherein change of a preload on the flyweight governor spring (<NUM>) adjusts a propeller (<NUM>) speed set point of the propeller (<NUM>);
a sensor (<NUM>) operable to sense a propeller (<NUM>) speed of the propeller (<NUM>);
one or more control devices communicatively coupled with the motor (<NUM>) of the propeller (<NUM>) governor and the sensor (<NUM>), the one more control devices configured to:
receive, from the sensor (<NUM>), data (<NUM>) indicative of the propeller (<NUM>) speed of the propeller (<NUM>);
characterized in that the one more control devices are configured to:
determine whether the propeller (<NUM>) speed exceeds a propeller (<NUM>) speed threshold; and
cause the motor (<NUM>) of the electric propeller governor (<NUM>) to change a preload on the flyweight governor spring (<NUM>) to change the propeller speed set point from a first propeller set point to a second propeller set point based at least in part on a determination that the propeller (<NUM>) speed exceeds the propeller (<NUM>) speed threshold.