Patent Description:
Engine components and fittings may be subjected to relatively high temperatures. Once subjected to excessive heating, fuel may undergo coking. Coking may cause solid deposits to form within fuel flow paths, causing undesirable effects such as blocked passageways and filters. Furthermore, excessive heating, cyclic loading, and other harsh conditions of engine components may lead to degradation of component health. Accordingly, response time of fuel actuation components may retard beyond desirable limits.

A prior art fuel actuation system and method for monitoring the same having the features of the preamble to claim <NUM> is disclosed in <CIT>.

From one aspect, the present invention provides a fuel actuation system in accordance with claim <NUM>.

From another aspect, the present invention provides a method for monitoring fuel actuation system health in accordance with claim <NUM>.

From yet another aspect, the present invention provides an electronic engine control (EEC) in accordance with claim <NUM>.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. The scope of the disclosure is defined by the appended claims. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by a controller, cause the controller to perform various operations. The term "non-transitory" is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se.

In various embodiments and with reference to <FIG>, a gas turbine engine <NUM> is provided. Gas turbine engine <NUM> may be a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. Alternative engines may include, for example, an augmentor section among other systems or features. In operation, fan section <NUM> can drive air along a bypass flow-path B while compressor section <NUM> can drive air along a core flow-path C for compression and communication into combustor section <NUM> then expansion through turbine section <NUM>. Although depicted as a turbofan gas turbine engine <NUM> herein, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

Gas turbine engine <NUM> may generally comprise a low speed spool <NUM> and a high speed spool <NUM> mounted for rotation about an engine central longitudinal axis A-A' relative to an engine static structure <NUM> via one or more bearing systems <NUM> (shown as bearing system <NUM>-<NUM> and bearing system <NUM>-<NUM> in <FIG>). It should be understood that various bearing systems <NUM> at various locations may alternatively or additionally be provided including, for example, bearing system <NUM>, bearing system <NUM>-<NUM>, and bearing system <NUM>-<NUM>.

Low speed spool <NUM> may generally comprise an inner shaft <NUM> that interconnects a fan <NUM>, a low pressure (or first) compressor section <NUM> and a low pressure (or first) turbine section <NUM>. Inner shaft <NUM> may be connected to fan <NUM> through a geared architecture <NUM> that can drive fan <NUM> at a lower speed than low speed spool <NUM>. Geared architecture <NUM> may comprise a gear assembly <NUM> enclosed within a gear housing <NUM>. Gear assembly <NUM> couples inner shaft <NUM> to a rotating fan structure. High speed spool <NUM> may comprise an outer shaft <NUM> that interconnects a high pressure compressor ("HPC") <NUM> (e.g., a second compressor section) and high pressure (or second) turbine section <NUM>. A combustor <NUM> may be located between HPC <NUM> and high pressure turbine <NUM>. A mid-turbine frame <NUM> of engine static structure <NUM> may be located generally between high pressure turbine <NUM> and low pressure turbine <NUM>. Mid-turbine frame <NUM> may support one or more bearing systems <NUM> in turbine section <NUM>. Inner shaft <NUM> and outer shaft <NUM> may be concentric and rotate via bearing systems <NUM> about the engine central longitudinal axis A-A', which is collinear with their longitudinal axes. As used herein, a "high pressure" compressor or turbine experiences a higher pressure than a corresponding "low pressure" compressor or turbine.

The core airflow C may be compressed by low pressure compressor <NUM> then HPC <NUM>, mixed and burned with fuel in combustor <NUM>, then expanded over high pressure turbine <NUM> and low pressure turbine <NUM>. Mid-turbine frame <NUM> includes airfoils <NUM> which are in the core airflow path. Low pressure turbine <NUM> and high pressure turbine <NUM> rotationally drive the respective low speed spool <NUM> and high speed spool <NUM> in response to the expansion.

In various embodiments and with further reference to <FIG>, a fuel actuation system <NUM> is illustrated in accordance with various embodiments. Gas turbine engine <NUM> may be operatively connected to fuel actuation system <NUM>. Fuel actuation system <NUM> may include electronic engine control (EEC) <NUM>, servo valve (SV) <NUM>, metering valve (MV) <NUM>, and/or feedback member <NUM>.

In various embodiments, EEC <NUM>, including processing circuitry <NUM> and memory <NUM>, may control fuel delivery to combustor <NUM>. EEC <NUM> may be operatively connected to SV <NUM> having a torque motor <NUM> that is selectively activated to control fuel delivery to MV <NUM>. In various embodiments, SV <NUM> may comprise a single stage servo valve. However, SV <NUM> may comprise any suitable servo valve. SV <NUM> may be fluidly connected to MV <NUM>. SV <NUM> may also include one or more screens <NUM> that prevent contaminate from entering the fuel used to control MV <NUM>. It should be understood that screens <NUM> may also be located in an adjacent fuel control component. EEC <NUM> may control torque motor <NUM> to cause SV <NUM> to deliver fuel to MV <NUM> to establish a set point which defines a desired fuel burn flow rate to combustor <NUM>. EEC <NUM> is shown to include a feedback member <NUM>. Feedback member <NUM> may provide position feedback from MV <NUM> to EEC <NUM>. Feedback member <NUM> may provide temperature feedback from MV <NUM> to EEC <NUM>. Feedback member <NUM> may provide pressure feedback from MV <NUM> to EEC <NUM>. Thus, feedback member <NUM> may include a temperature sensor, a pressure sensor, and/or a position sensor.

In various embodiments, processing circuitry <NUM> may include any combination of processing circuits known in the art, such as one or more microprocessors, microcontrollers, digital signal processors, and/or programmable logic devices. The memory <NUM> may store executable instructions and data to implement control logic of EEC <NUM>. Memory <NUM> may comprise a tangible, non-transitory storage medium and may store data used, for example, in trending and prognosis purposes. EEC <NUM> may also include an SV interface <NUM> that converts data from SV <NUM> into a format usable by processing circuitry <NUM> such as a frequency-to-digital converter, for example. EEC <NUM> may further include a feedback member interface <NUM> that receives signals from feedback member <NUM> which provides an indication of MV <NUM> opening as set by torque motor <NUM> and also provides a pathway for EEC <NUM> to control torque motor <NUM> to set a new valve opening for MV <NUM>. For example, EEC <NUM> may source a controlled amount of current to torque motor <NUM> as a metering valve control signal.

In various embodiments, MV <NUM> is generally actuated or moved via hydraulic or fueldraulic pressure. A hydraulic system, such as a fuel system, may be in fluidic communication with SV <NUM>. Torque motor <NUM> of SV <NUM> may receive current from a power source, such as EEC <NUM> for example, to move a moveable member of SV <NUM> and in response to the moving, a controlled hydraulic pressure is supplied to MV <NUM>.

With reference to <FIG>, a metering valve <NUM> is illustrated, in accordance with various embodiments. In various embodiments, metering valve <NUM> (see <FIG>) may be similar to metering valve <NUM>. Metering valve <NUM> may comprise a moveable member <NUM>. Moveable member <NUM> is illustrated in <FIG> in a first position. Although illustrated in <FIG> as being in a particular position, the first position of moveable member <NUM> may any suitable position including a closed or open position.

With reference to <FIG>, a metering valve <NUM> is illustrated, in accordance with various embodiments. Moveable member <NUM> is illustrated in <FIG> in a second position. Although illustrated in <FIG> as being in a particular position, the second position of moveable member <NUM> may any suitable position including a closed or open position.

In various embodiments, with reference to <FIG>, the health of fuel actuation system <NUM> may be monitored via EEC <NUM>. System parameters such as time of travel of MV <NUM>, fuel temperature, and fuel pressure may be sensed by feedback member <NUM> and stored into memory <NUM>. A history of these system parameters may be trended and analyzed by EEC <NUM> to determine a diagnosis as well as a prognosis of the health of fuel actuation system <NUM>. With further reference to <FIG>, a method <NUM> for monitoring the health of fuel actuation system <NUM> is provided, in accordance with various embodiments. Method <NUM> may include moving MV <NUM> from a first position to a second position (see step <NUM>). MV <NUM> may be moved via any suitable method. In various embodiments, MV <NUM> may be moved by increasing or decreasing current supplied to SV <NUM>. In various embodiments, a travel time may be detected when MV <NUM> is moved from the first position to the second position (see step <NUM>). The travel time may be the total duration of time that it takes for MV <NUM> to move from the first position to the second position. The travel time may be stored to memory <NUM> (see step <NUM>). Accordingly, over time, multiple travel times may be stored to memory, thus generating a historical trend of travel times or a travel time history. A controller, such as EEC <NUM>, may determine the health of fuel actuation system <NUM> based on the travel time history (see step <NUM>). The health of fuel actuation system <NUM> may be based on a level of degradation of the fuel actuation system <NUM>. The health of fuel actuation system <NUM> may be based on a level of degradation of the travel time of MV <NUM>.

With further reference to <FIG>, a method <NUM> for monitoring the health of fuel actuation system <NUM> is provided, in accordance with various embodiments. Method <NUM> may include moving MV <NUM> from a first position to a second position for a pre-determined duration (see step <NUM>). MV <NUM> may be moved via any suitable method. In various embodiments, MV <NUM> may be moved by increasing or decreasing current supplied to SV <NUM>. In various embodiments, a travel distance may be detected when MV <NUM> is moved from the first position to the second position (see step <NUM>). The travel distance may be the distance between the first position and the second position. The travel distance may be stored to memory <NUM> (see step <NUM>). Accordingly, over time, multiple travel distances may be stored to memory, thus generating a historical trend of travel distances or a travel distance history. A controller, such as EEC <NUM>, may determine the health of fuel actuation system <NUM> based on the travel distance history (see step <NUM>). The health of fuel actuation system <NUM> may be based on a level of degradation of the fuel actuation system <NUM>. The health of fuel actuation system <NUM> may be based on a level of degradation of the travel distance of MV <NUM>.

With reference to <FIG>, a plot <NUM> of travel time <NUM> is plotted verses time. Travel time <NUM> may decrease over time and degradation <NUM> of travel time <NUM> may occur. Degradation <NUM> may be the difference between initial travel time <NUM> and travel time <NUM>. Thus, degradation <NUM> may be a change in travel time <NUM>. In various embodiments, degradation <NUM> may vary over time. In various embodiments, degradation <NUM> may increase over time. Although some degradation <NUM> of travel time <NUM> might be expected, excessive decrease in travel time <NUM> may indicate poor health of fuel actuation system <NUM> (see <FIG>). Accordingly, plot <NUM> illustrates a travel time history. Although illustrated with respect to travel time, plot <NUM> may also similarly illustrate a degradation of travel distance over time. Stated another way, travel time may be replaced with travel distance in <FIG> to similarly illustrated travel distance in inches or centimeters. In this manner a travel distance history may be created.

With reference to <FIG>, another method <NUM> for monitoring the health of fuel actuation system <NUM> is provided. Method <NUM> may include detecting an engine shutdown (see step <NUM>). Detecting an engine shutdown may include at least one of determining if an aircraft is on the ground, determining if an engine is at ground idle, and determining if an overspeed test is successful. With further reference to <FIG>, method <NUM> may include moving MV <NUM> from a first position to a second position (see step <NUM>). Step <NUM> may be similar to step <NUM> (see <FIG>) and/or step <NUM> (see <FIG>). At least one of a travel time, a travel distance, a fuel temperature, or a fuel pressure may be detected when MV <NUM> is moved from the first position to the second position (see step <NUM>). The travel time may be the total duration of time that it takes for MV <NUM> to move from the first position to the second position. The travel distance may be the distance between the first position to the second position. The fuel temperature may be the temperature of a fuel located in fuel actuation system <NUM>. Fuel temperature may be detected via a temperature sensor of feedback member <NUM>. The fuel pressure may be a pressure of a fuel located in fuel actuation system <NUM>. Fuel pressure may be detected via a pressure sensor of feedback member <NUM>. However, fuel pressure may be determined via any suitable method. The travel time, travel distance, fuel temperature, and/or fuel pressure may be stored to memory <NUM> (see step <NUM>). Similar to the travel time <NUM> (see <FIG>), the travel distance, the fuel temperatures, and the fuel pressures may be stored to memory, thus generating, over time, travel distance trends, fuel temperature trends, and fuel pressure trends, or travel distance history, fuel temperature history, and fuel pressure history. In various embodiments, the MV <NUM> may be moved from the second position to a third position (see step <NUM>). In various embodiments, the second position may be an open position. In various embodiments, the third position may be a closed position. However, the second position and the third position may comprise any suitable position. At least one of a second travel time, a second travel distance, a second fuel temperature, or a second fuel pressure may be detected when MV <NUM> is moved from the second position to the third position (see step <NUM>). A controller, such as EEC <NUM>, may determine a level of degradation of the fuel actuation system <NUM> based on the travel time history and/or the travel distance history. A controller, such as EEC <NUM>, may determine a level of degradation of the fuel actuation system <NUM> based on the travel distance history in a manner similar to the travel time history. A controller, such as EEC <NUM>, may determine a level of degradation of the fuel actuation system <NUM> based on the fuel temperature history in a manner similar to the travel time history. A controller, such as EEC <NUM>, may determine a level of degradation of the fuel actuation system <NUM> based on the fuel pressure history in a manner similar to the travel time history. Accordingly, A controller, such as EEC <NUM>, may determine the health of fuel actuation system <NUM> (see step <NUM>). In various embodiments, EEC <NUM> may indicate the determined system health (see step <NUM>). For example, EEC <NUM> may output a signal to a display to indicate the health of fuel actuation system <NUM>. Such indication may be performed via any suitable indicator such as, for example, a light, a message on a display, text, symbols, etc. For example, EEC <NUM> may output a signal to a display or other controller to indicate the degradation or health of fuel actuation system <NUM>.

In various embodiments, with reference to <FIG>, the health of a system may be determined by comparing the degradation <NUM> of one system, with the degradation of one or more other systems. For example, one system may comprise a degradation which is compared with the average degradation of a group of systems.

Claim 1:
A fuel actuation system (<NUM>) comprising:
a servo valve (SV) (<NUM>) including a torque motor (<NUM>) and at least one screen (<NUM>);
a metering valve (MV) (<NUM>; <NUM>) fluidly connected to the SV (<NUM>); and
an electronic engine control (EEC) (<NUM>) operatively connected to the SV (<NUM>), the EEC (<NUM>) being configured and disposed to:
determine a travel distance of the MV (<NUM>; <NUM>) and at least one of a pressure of a fuel and a temperature of the fuel; and
store the travel distance of the MV (<NUM>; <NUM>) and the at least one of the pressure of the fuel and the temperature of the fuel to a memory (<NUM>) to generate a travel distance history and at least one of a fuel temperature history and a fuel pressure history,
characterised in that the EEC (<NUM>) is further configured and disposed to:
determine a level of degradation of the fuel actuation system (<NUM>) based on the travel distance history and the at least one of the fuel temperature history and the fuel pressure history.