Patent Description:
<CIT> discloses a pitch control mechanism for controlling the pitch of propeller assembly. The pitch control mechanism has a hydraulic actuator, main hydraulic fluid supply lines, first back-up hydraulic fluid supply lines, and second back-up hydraulic fluid supply lines. The hydraulic actuator has first and second hydraulic cylinders that each angularly displace the propellers between fine and coarse positions. The main hydraulic fluid supply lines comprise check valves and supply fluid to the first and second hydraulic cylinders for operating the hydraulic cylinders. The first back-up hydraulic fluid supply lines comprise a check valve and supply fluid to the first hydraulic cylinder for displacing the propellers to a coarser position. The second back-up hydraulic fluid supply lines comprise a check valve and supply fluid to the second hydraulic cylinder for displacing the propellers to a coarser position. When the main hydraulic fluid supply lines supply inadequate fluid, the first and/or second back-up hydraulic fluid supply lines can supply fluid for displacing the propellers to a coarser position, where the fluid is provided by a back-up hydraulic power source comprising a valve.

In accordance with the invention, a system is provided as defined by claim <NUM>.

In accordance with one or more embodiments or any of the system embodiments above, the first medium can include a hydraulic force used to decrease the pitch of the propellers.

In accordance with one or more embodiments or any of the system embodiments above, the second medium can include a hydraulic force used to increase the pitch of the propellers.

In accordance with one or more embodiments or any of the system embodiments above, a connection of the protection actuator can receive atmospheric pressure or the first medium.

In accordance with one or more embodiments or any of the system embodiments above, the third valve can include a solenoid operated valve that generates a controlled magnetic field that provides a force acting on the third valve.

In accordance with one or more embodiments or any of the system embodiments above, the third valve can include a biasing spring that selects the protection mode during a power loss.

In accordance with the invention, a method is provided as defined by claim <NUM>.

In accordance with one or more embodiments or any of the method embodiments above, a sensor can monitor the dual piston actuator for the control loss.

In accordance with one or more embodiments or any of the method embodiments above, the protection mode can include a hydraulic pitch-lock condition with a capability to increase the pitch of the propellers of the aircraft.

In accordance with one or more embodiments or any of the method embodiments above, the primary and protection actuators can control the propellers of an aircraft in accordance with the supply of the first and second mediums and the first medium can include a hydraulic force used to decrease the pitch of the propellers.

In accordance with one or more embodiments or any of the method embodiments above, the primary and protection actuators can control the propellers of the aircraft in accordance with the supply of the first and second mediums and the second medium can include a hydraulic force used to increase the pitch of the propellers.

In accordance with one or more embodiments or any of the method embodiments above, the third valve can include a solenoid operated valve that generates a controlled magnetic field that provides a force acting on the third valve.

In accordance with one or more embodiments or any of the method embodiments above, the third valve can include a biasing spring that selects that the protection mode during a power loss.

Embodiments herein relate to a dual actuator hydraulic pitch-lock propeller system and operations thereof. Accordingly, embodiments herein provide a safe, certifiable, light weight, and simple design where no single failure or malfunction in a propeller system results in an unintended travel of propeller blades to a position below an in-flight low-pitch position.

<FIG> depicts a dual actuator hydraulic pitch-lock propeller system <NUM> (herein referred to as a system <NUM>) according one or more embodiments. The system <NUM> includes a dual piston actuator (e.g., a primary actuator <NUM> and a protection actuator <NUM>). The system <NUM> also includes at least three valves, such as two increase pitch check valves <NUM> and <NUM> and a valve <NUM>. The system <NUM> can be incorporated into any rotating hardware of an aircraft, such as with respect to variable pitch propellers, on a rotating side of the propellers. Note that elements of the system <NUM> can also be mounted remotely on a stationary side of the propellers, such as the valve <NUM>.

The system <NUM> operates between a first mode and a protection mode. The first mode results in a normal operation of the propellers. The protection mode results in a hydraulic pitch-lock condition with a capability to increase pitch should a hydraulic control pressure be available. The protection mode is the state of the system <NUM> being shown in <FIG>.

The primary actuator <NUM> and the protection actuator <NUM> are responsible for moving and controlling a mechanism or system (e.g., propeller blades). The primary and protection actuators <NUM> and <NUM> are operated by hydraulic fluid or pneumatic pressure. The system receives/provides at least two mediums, such as hydraulic fluid and/or engine oil (e.g., PFINE <NUM> and PCOURCE <NUM>), via one or more channels, piping, lines, ducts, or the like. The primary and protection actuators <NUM> and <NUM> operate in a similar manner, where an internal piston is driven in either direction based on the application of the at least two mediums (to increase and decrease a pitch of the propellers of the aircraft).

In accordance with one or more embodiments, a first medium is PFINE <NUM>, which can be a hydraulic force used to decrease pitch of the propeller blades. Further, a second medium is PCOURCE <NUM>, which can be a hydraulic force used to increase pitch of the propeller blades (e.g., increasing pitch puts the propellers in a low drag configuration). Further, the connection <NUM> can provide atmospheric pressure or connect to PFINE <NUM>.

The check valves <NUM> and <NUM> can be any type of valve that closes to prevent backward flow of a medium (e.g., a hydraulic fluid and/or an engine oi). The check valves <NUM> and <NUM>, in operation, allow an increase in pitch by stabilizing an amount of PCOURCE <NUM> provided to each of the primary and protection actuators <NUM> and <NUM> (e.g., preventing any decrease in pitch).

The valve <NUM> can be any type of inductor/electromagnet/solenoid operated valve, the purpose of which is to generate a controlled magnetic field. The valve <NUM> can include a biasing spring <NUM>, which ensures that the protection mode is selected in case of power loss. The valve <NUM> can include a first section <NUM> and a second section <NUM>. The first section <NUM> is related to the protection mode, such that PCOURCE <NUM> is provided through the check valves <NUM> and <NUM> to the primary and protection actuators <NUM> and <NUM> when the first section <NUM> is selected. The second section <NUM> is related to the first mode, such that PCOURCE <NUM> is provided directly to the primary and protection actuators <NUM> and <NUM> when the second section <NUM> is selected. Thus, the second section <NUM> is in position for providing PCOURCE <NUM> directly to the primary and protection actuators <NUM> and <NUM> when the controlled magnetic field is operational. Further, the biasing spring <NUM> drives the first section <NUM> into position for providing PCOURCE <NUM> through the check valves <NUM> and <NUM> when the controlled magnetic field is gone due to a loss of power. In accordance with one or more embodiments, the valve <NUM> utilizes an additional hydraulic line to the rotating side as a selection force to counteract the bias spring <NUM> and position the valve <NUM>.

The system <NUM> can include a controller <NUM> and includes at least one sensor <NUM>. The controller <NUM> can be an electronic, computer framework comprising and/or employing any number and combination of computing device and networks utilizing various communication technologies, as described herein. The controller <NUM> can be easily scalable, extensible, and modular, with the ability to change to different services or reconfigure some features independently of others. The controller <NUM> has a processor, also referred to as a processing circuit, microprocessor, computing unit, which is coupled via a system bus to a system memory and various other components. In accordance with one or more embodiments, the controller <NUM> can be, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) that may execute computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform operations (such as those described with respect to <FIG>).

The sensor <NUM> can be any transducer that converts an environmental condition (e.g., pressure) to an electoral signal. In accordance with one or more embodiments, the system <NUM> can utilize a single sensor (as shown in <FIG>) to minimize a complexity of the primary and protection actuators <NUM> and <NUM>. The sensor <NUM> can monitor the dual piston actuator (e.g., the primary actuator <NUM> and the protection actuator <NUM>) to ensure adequate latent fault detection (e.g., control loss detection). In an example that does not fall within the scope of the claims, control loss detection can also be identified via an actuator position feedback (if pitch position is not following a command) via pulse targets, transfer tube rotary variable differential transformer, or the like.

In accordance with one or more embodiments, the controller <NUM> can operate the valve <NUM> based on signals from the sensor <NUM> (e.g., along with pulse targets, transfer tube rotary variable differential transformer, or the like), such as by electrically disabling or turning off the controlled magnetic field of the valve <NUM>. The controlled magnetic field provides a force that acts on the third valve <NUM>. In this regard, the protection actuator <NUM> can increase pitch and rely upon aerodynamic loads toward flat pitch for its counterbalancing force based on the sensor <NUM>. Further, due to the biasing spring <NUM>, if the controller <NUM>, the sensor <NUM>, and/or the valve <NUM> lose power, the valve <NUM> defaults to the protection mode.

<FIG> depicts a process flow <NUM> illustrating an example operation of a dual actuator hydraulic pitch-lock propeller system <NUM> according one or more embodiments. The process flow <NUM> begins at block <NUM>, where an engine start is performed. An engine start can include a built in test to decrease pitch and verify integrity of the system <NUM>. Note that the built in test can be performed in a protection mode momentarily to ensure a pressure developed is within a normal range expected. With a successful engine start (and an expected pressure is reached), the process flow <NUM> proceeds to block <NUM>.

At block <NUM>, the system <NUM> operates in a first mode. The first mode results in the normal operation of the propellers. For instance, the second section <NUM> of the valve <NUM> is positioned such that PCOURCE <NUM> is provided directly to the primary and protection actuators <NUM> and <NUM>. Next, at decision block <NUM>, the system <NUM> determines whether a control loss is detected. Control loss includes when a PCOURCE <NUM> is operating outside of expectations, whether due to an increase or decrease of pressure (e.g., hydraulic pressure is lost). As discussed herein, a control loss can be detected by the monitoring of the sensor <NUM> or if a pitch position is not following a command. Further, the control loss can include when a loss of power occurs. If no control loss is detected, the process flow <NUM> returns to block <NUM> (as indicated by the No arrow). If the control loss is detected, the process flow <NUM> proceeds to block <NUM> (as indicated by the Yes arrow).

At block <NUM>, the system <NUM> operates in a protection mode. In this regard, a command can be sent to the valve <NUM> to enter the protection mode, which will cause the primary and protection actuators <NUM> and <NUM> to hold pitch (e.g., at a minimum inflight angle) due to the check valve <NUM> and <NUM>.

At block <NUM> the system <NUM> can receive an input. For instance, the controller <NUM> can receive an input from a pilot of an aircraft. The input can direct the system <NUM> to continue operating in the protection mode. In this case, the process flow <NUM> proceeds to block <NUM> (as indicated by A arrows). Note that if no input is received, the system <NUM> can default to continue operating in the protection mode. Optionally, while under the protection mode, the system <NUM> can perform a pressure recover check (as shown by block <NUM>). That is, if the control loss is still detected, then the process flow <NUM> proceeds to block <NUM> and the system <NUM> remains in the protection mode. However, if pressure has recovered, as detected by the sensor <NUM>, then the system <NUM> can return to the first mode of operation. In this case, the process flow <NUM> proceeds to block <NUM> (as indicated by Yes arrow).

Returning to block <NUM>, if the input directs the system <NUM> to feather, then the process flow <NUM> proceeds to block <NUM> (as indicated by the B arrow). At block <NUM>, feathering the propellers is performed. That is, a hydraulic flow is increased to increase pitch to decrease the drag (e.g., high pitch low drag configuration).

Claim 1:
A system comprising:
a dual piston actuator configured, in use, to control a pitch of propellers of an aircraft, comprising a primary actuator (<NUM>) and a protection actuator (<NUM>),
wherein, in use, the primary and protection actuators are configured to move to increase and decrease a pitch of the propellers of an aircraft in response to a supply of first and second mediums; and
a plurality of valves comprising a first check valve (<NUM>), a second check valve (<NUM>), and a third valve (<NUM>),
wherein
the third valve is configured to, based on a pressure signal from a sensor, operate between a first mode and a protection mode that results in a hydraulic pitch-lock condition with a capability to increase the pitch of the propellers,
wherein when operating in the first mode, the second medium is directed by the third valve directly to the primary and protection actuators without passing through the first and second check valves, respectively, wherein when operating in the protection mode, the third valve is arranged such that the third valve directs the second medium to the primary and protection actuators through the first and second check valves, respectively, that allow the actuators to hold pitch.