Patent Application
20170167287
The present subject matter relates generally to systems and methods for measuring torque.
Measuring torque supplied by, and to, a rotating shaft can be an important operation for many rotating machines. In the field of gas turbine engines, it is especially important to closely monitor and accurately measure the torque output of the engine to understand engine performance and health. By closely monitoring output torque values, potential problems may be identified before they occur. For instance, lower than expected torque output may be indicative of sub-optimal engine operation. In addition, output torque values may be used to estimate the life cycle of various engine components. Real time measurement of output torque values may permit the estimations of the life of an engine component to be repeatedly updated and revised. Moreover, real time measurement of output torque may be used to guarantee that the required output power is available at any given time.
Of course, measurements of torque are only useful to the degree that they can be considered accurate. Current methods for measuring torque are generally limited in their ability to consistently gather accurate information from a rotating shaft. For instance, some existing systems rely on reluctance sensors to monitor shaft rotation. Such systems must use rotational readings to estimate shaft strain generated at the shaft away from the sensor location. However, by relying on rotational readings alone, relevant information on strain may be lost and lead to inaccurate torque measurements.
Other systems may detect shaft strain in order to determine torque. However shaft strain, expansion, or twist alone may fail to accurately measure torque. Most rotating shafts will be subjected to significant strains, not only due to rotational forces and torque, but to additional factors, such as temperature, bending, and vibration. Although these additional factors may be insignificant to strain measured in some applications, they can be quite significant in understanding the performance and health of a gas turbine engine. The high-temperatures and environmental variations which gas turbine engine components are subjected to can greatly increase the strain to the engine's various rotational systems. Therefore, measuring strain without understanding the contributions due to temperature and other factors of variation may not provide an accurate indication of the torque output of a gas turbine engine.
Moreover, existing strain-based sensing systems often require regular service in order to provide accurate strain measurements due to, for instance, the effects of long term drift or reliability of these systems. Operation of the measured part or apparatus must be ceased in order to calibrate or recalibrate the sensing systems. In the case of a gas turbine engine, the maintenance for calibration or recalibration can be time consuming and expensive.
As a result, there is a need for a torque sensing system which can provide accurate real-time measurements of torque in a gas turbine engine. There is further need for a system that can account for operational variations to which the engine will be subjected.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One example aspect of the present disclosure is directed to a system for measuring torque for a gas turbine engine shaft. The system can include a torque sensor positioned at an engine shaft. The torque sensor, itself, can include a strain sensor for obtaining a strain measurement of the engine shaft and a temperature sensor for obtaining a temperature measurement of the engine shaft. The system can also include a wireless communication element operably connected to the torque sensor for transferring the strain measurement and the temperature measurement. In addition, one or more memory storage units co-located with the torque sensor can be provided. The one or more memory storage units can store calibration information for the system. The calibration information is used by one or more processors to calibrate the strain measurement obtained by the strain sensor and the temperature measurement obtained by the temperature sensor.
In accordance with another example aspect of the present disclosure, a method for measuring torque for a gas turbine engine shaft is provided. The method can include obtaining a strain measurement of an engine shaft from a strain sensor positioned at an engine shaft, as well as obtaining a temperature measurement from a temperature sensor positioned at the engine shaft. The method can further include obtaining calibration information from one or more memory storage units co-located with the strain sensor. Moreover, the method can include determining a torque measurement based at least in part on the strain measurement, the temperature measurement, and calibration information.
Variations and modifications can be made to these example embodiments of the present disclosure.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.
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 “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 of the engine and an outer engine circumference.
Example aspects of the present disclosure include a system and method for accurately measuring the torque to which one or more engine shafts are subjected. The system can be fully calibrated to inherently compensate for various factors that might otherwise impair accuracy. Moreover, the system can collect data directly at the engine shaft and wirelessly transmit its readings and calibration information to a monitor or controller distinct and separate from the engine shaft.
Referring now to the drawings,
As shown in
The example turboprop embodiment 10 also includes a radial driveshaft or power take-off shaft 44 that extends from core turbine engine 14 for connection with an accessory gearbox 48. During normal operation, the radial driveshaft 44 transfers power from the engine core 14 to the accessory gearbox 48. During engine startup, the radial driveshaft 44 can also transfer power from a starter located in the accessory gearbox 48 to the engine core 14.
Turning to
As illustrated in
The torque sensor 104 can be configured to measure at least a portion of strain, which the controller 108 can use to help calculate an output torque value (e.g., an overall value of dynamic rotational torque which is generated through the core engine 14). Although conventional systems have been unable to provide calibrated torque sensors within these extreme engine environments of a core engine 14, positioning the torque sensor 104 directly on the engine shaft 102 may advantageously reduce the need to infer or indirectly estimate the torque at the engine shaft 102. Moreover, the torque sensor 104 can be positioned at a non-parallel torque section of the engine shaft 102 (e.g., a shaft section that does not include multiple torque inputs and/or outputs). In such embodiments, the core engine 14 can include a singular torque path free of any alternate torque paths. The torque sensor 104 can, thereby, be subjected to and measure the entire rotational torque being generated through the engine core 14. In addition, positioning the torque sensor 104 on a non-parallel torque section may advantageously permit consistent measurement of torque output.
As shown, the example system 100 of
The example embodiment of the torque sensor 104 shown in
As shown in
The system 100 can further include a controller 108 having one or more processor 110. The processor(s) 110 can be configured for receiving the calibration parameters of the sensor 104 and generating calibrated torque values according to one or more sensor signals received from the torque sensor 104. Optionally, the controller 108 can include a full authority digital engine control (FADEC), or another suitable engine control unit. In some embodiments, the controller 108 includes a discrete processor memory unit 115 and wireless interrogator 120 in operable communication with the processor(s) 110.
As shown, the processor(s) 110 can be in operable communication with the torque sensor 104 and a co-located memory storage unit 112. The processor(s) 110 can include a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed and programmed to perform or cause the performance of the functions described herein. The processor(s) 110 can also include a microprocessor, or a combination of the aforementioned devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).
In optional embodiments, one or more memory units 115 can be provided and comprise one or more memory elements. For instance, the memory unit(s) 115 can include, but are not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory, EEPROM, NVRAM or FRAM), and/or other suitable memory elements. The memory units 115 can store information accessible by processor(s) 110, including instructions that can be executed by processor(s) or information about the engine shaft 102 or sensor(s) 104. For example, the instructions can be software or any set of instructions that when executed by the processor(s) 110, cause the processor(s) 110 to perform operations. For the embodiment depicted, the instructions can include a software package configured to operate the system 100 to, for instance, implement the example method (200) described below with reference to
As shown in the example embodiment of
In optional embodiments, the interrogator 120 is operably coupled to the torque sensor 104 through one or more wireless network. In specific embodiments, the controller 108 can be configured to transmit an electronic signal (e.g., an interrogator signal) across a communications network via one or more wireless protocol standards from the interrogator 120 and/or processor(s) 110 to the torque sensor 104. For example, in certain example embodiments, the controller 108 can be configured to communicate with the torque sensor 104 using a point-to point communication networks (such as radio frequency identification networks, near field communications networks, etc.), a wireless sensor network (such as a Bluetooth communication network), a wireless local area network (WLAN), or other cellular or wireless communications networks. In some such embodiments, the controller 108, the interrogator 120, and/or the torque sensor 104 can include matching wireless communications modules to transmit and/or receive wireless electronic signals according to the same wireless protocol standard. In alternative embodiments, the controller 108 can be configured to communicate with the torque sensor 104 through a raw radio frequency signal, optical signal, or magnetic signal.
As illustrated in
The memory storage unit(s) 112 can store calibration information for the sensor 104 for calibrating or adjusting one or more sensor measurements. The memory storage unit(s) 112 can include, but is not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory, EEPROM, NVRAM or FRAM), and/or other suitable memory elements. As shown, the memory storage unit(s) 112 can be operably connected with the controller 108 and processor(s) 110 (e.g., via the sensor antenna 106, calibration antenna 118, and/or wireless interrogator 120, similarly or in addition to the torque sensor 104). Accordingly, the calibration information can be received by the processor(s) 110 as part of the sensor value signals initially transmitted from the torque sensor 104 (e.g., as a single output signal).
The calibration information can provide a known or estimated relationship between a measured value and an actual or accurate value. Specifically, information concerning one or more correction parameter can be included as part of the calibration information stored on the memory storage unit(s) 112. In certain embodiments, an engine model is further included. The engine condition model can be included in the controller 108 and/or processor(s) 110 and associate the correction parameter with measurements obtained from the torque sensor 104. For instance, the engine condition models can correlate a measured strain and/or temperature value against a model strain and/or temperature value. In other words, the engine condition models of such embodiments establishes a relationship between the measurements that are initially obtained from the torque sensor (i.e., the measured values) and a more accurate value of the strain and/or temperature conditions at the engine shaft 102 (i.e., the rectified values). In one example embodiment, once strain and temperature measurements are obtained, the engine condition model can allow the obtained measurements to be used with the correction parameter to generate a rectified torque value. Optionally, the engine condition model can include a suitable algorithm, predetermined data graph, or correlated reference table that links a measured value to a rectified value.
In some embodiments, the engine condition model can be contingent upon predetermined historical data values. The historical data values can be provided from past values obtained by testing at known conditions. For example, the correction parameter can adjust a newly-obtained strain measurement based on past measurements at one or more known temperature. In alternative or additional embodiments, the correction parameter can adjust an obtained strain measurement based on past measurements at one or more known rotational velocities. Moreover, the correction parameter can adjust an obtained strain measurement based on other measurements, such as vibration at the engine shaft 102, exhaust gas temperature, engine inlet temperature, or engine combustion pressure. Thus, the correction parameter can include rotational velocity of the engine shaft 102, temperature at the engine shaft 102, vibration at the engine shaft 102, exhaust gas temperature, inlet temperature, or engine combustion pressure.
In optional embodiments, the calibration information derived for a single system unit can be included in a plurality of system units. In other words, the memory storage units 112 of multiple discrete systems 100 will include substantially identical calibration information. After a first system unit is calibrated, that calibration information can be subsequently incorporated in succeeding system units. Advantageously, this may allow multiple system units to be calibrated according to the engine condition model derived for a single unit, reducing calibration and service time required for each system unit
As shown in
Some embodiments, such as the exemplary embodiment of
In additional embodiments, the processor(s) 110 is configured to receive calibration information stored at the memory storage unit(s) 112. Specifically, calibration information can be electronically or wirelessly transmitted to the processor(s) 110 from the memory storage unit(s) 112. For instance, in certain embodiments, calibration information is provided from the memory storage unit(s) 112 via the wireless interrogator 120 and antennas 106 and 118. In some such embodiments, calibration information is provided in response to an interrogation signal initiated by the processor(s) 110 at the wireless interrogator 120. Similar to the interrogation signal described above, the interrogation signal to the memory storage unit(s) 112 can be transferred via the stationary antenna 118 and sensor antenna 106. In response to the interrogation signal, calibration information can be transmitted through the sensor antenna 106 and stationary antenna 118 to the controller 108. The calibration information can be transmitted in isolation or together with a strain measurement and/or temperature measurement (e.g., as a single output signal). Optionally, the calibration information can be transmitted to the wireless interrogator 120 before being received by the processor(s) 110.
The processor(s) 110 can be configured to use measured values and calibration information to calculate a measured torque value and/or adjust a measured sensor value. For instance, in an embodiment wherein the processor(s) 110 receives a strain measurement from the strain sensors 114 and a correction parameter from the memory storage unit(s) 112, the processor(s) can subsequently apply the correction parameter to the strain measurement. According to the correction parameter, the received strain measurement can be either increased or decreased.
In additional or alternative embodiments, the processor(s) 110 is configured to adjust a first sensor measurement by a second sensor measurement. Advantageously, the processor(s) 110 can, thus, provide contemporaneous calibration of the sensor 104. In specific embodiments, the processor(s) 110 is configured to receive a strain measurement from one or more strain sensor 114 and a temperature measurement from one or more temperature sensor 116. Such embodiments of the processor(s) 110 can be further configured to adjust the received strain measurement according to the received temperature measurement. Specifically, the received strain measurement can be altered to distinguish between rotational strain (e.g., strain derived from a rotational torque output) and thermal strain (e.g., strain derived from thermal expansion or contraction of the engine shaft 102), as well as the shaft material's modulus change due to the changes in temperature. Accordingly, thermal strain can be distinguished from received strain measurements to provide a rotational strain value for the accurate calculated torque measurement.
In some embodiments, the processor(s) 110 is further configured to measure or calculate an output torque value based, at least in part, on information or values received from the torque sensor 104. For instance, in one embodiment, once the processor(s) 110 rectifies or adjusts a strain measurement received from the strain sensor 114, the processor(s) 110 can calculate a calibrated torque measurement value for rotational torque occurring about the rotational axis A of the engine shaft 102. The calculation can be made according to any suitable method or algorithm without deviating from the scope of the present disclosure.
Turning
Turning to
Although two torque sensors 104 are shown in
At (210), the method can include obtaining a strain measurement at an engine shaft from a strain sensor positioned on an engine shaft. Specifically, the engine shaft can include a power take-off shaft, a low pressure turbine shaft, a high pressure turbine shaft, a fan shaft, an engine coupling shaft, or other suitable rotating shaft. In some embodiments, the strain sensor can include a direct write strain sensor, radio-frequency identification sensor, surface acoustic wave sensor, bulk acoustic wave sensor, half-bridge strain gauge sensor, or full-bridge strain gauge sensor disposed at least partially on the engine shaft. In additional or alternative embodiments, the strain sensor can include a magnetostrictive sensor, magnetoelastic sensor, magnetoresistive sensor, or optical moire sensor. Moreover, in some embodiments, (210) can include receiving a strain measurement wirelessly from the strain sensor, as described above.
At (220), the method (200) includes obtaining a temperature measurement from a temperature sensor positioned on the engine shaft. The temperature sensor can include a surface acoustic wave sensor, bulk acoustic wave sensor, resistance temperature detection sensor, thermocouple sensor, or pyrometric sensor disposed at least partially on the engine shaft, and can be further enhanced using an engine thermal model. Optionally, (210) further includes receiving a temperature measurement wirelessly from the temperature sensor, as described above.
At (230), the method (200) includes obtaining calibration information from one or more memory storage units co-located with the strain sensor. The calibration information can include a correction parameter, as discussed above. For instance, the correction parameter of some embodiments a rotational velocity of the engine shaft, temperature at the engine shaft, vibration at the engine shaft, exhaust gas temperature, inlet temperature, or engine combustion pressure. Moreover, an engine condition model can be associated with the correction parameter.
Optionally, one or more of the steps (210), (220), or (230) can be contingent upon transmission of a wireless interrogation signal. As a result, optional embodiments of the method (200) can include initiating a wireless interrogation signal at a wireless interrogator, as described above. In certain embodiments, the wireless interrogator is operably connected to a processor(s) and includes a passive radio-frequency interrogator, an active radio-frequency interrogator, or an optical interrogator.
At (240), the method (200) includes determining a torque measurement based at least in part on the strain measurement, the temperature measurement, and the calibration information. As discussed above, the engine condition model can be configured to correlate measured strain and/or temperature values to one or more rectified values. In certain embodiments, a rotational strain of the engine shaft is distinguished from thermal strain. Moreover, a strain measurement can be adjusted based, at least in part on, the determined thermal strain. Thus, a rotational strain value that excludes thermal strain may be provided.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
