Electric Actuator External Motor Positioning for High-Temperature Engine Control
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Solution Overview
Problem
High-temperature environments in gas turbine engines pose challenges for electric actuation systems, leading to reduced accuracy and responsiveness due to overheating and mechanical interactions, which impede localized loop closure and actuation bandwidth.
Innovation Solution
An electric actuator system with an electric motor, position feedback shaft, and rotational position sensor is designed to align a gear interface with a variable geometry adjustment interface within the engine, positioning the motor and sensor externally to avoid high temperatures, using a concentric drive and feedback shaft configuration and a retracting mechanism to decouple the drive shaft from the output shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric actuation components are placed within the high-temperature engine core environment, then direct actuation control is achieved, but the components overheat and cease operation above 350 degrees F
Solution Approach 1:
The electric motor and rotational position sensor are extracted from the high-temperature engine core environment and positioned externally, connected via shafts that extend through the casing. This removes the sensitive electric components from the harmful thermal environment while maintaining their actuation function.
Solution Approach 2:
Shafts serve as intermediary mechanical elements that transmit rotational motion and position feedback between the externally located electric motor/sensor and the internal gear interface. These shafts act as mediators that bridge the boundary between the cool external environment and the hot internal engine environment.
2Power
If position feedback is derived through a gearbox with mechanical linkages, then gear reduction is achieved, but accuracy is reduced due to linkage torsion, gear stiffness, and shaft stiffness
Solution Approach 1:
The patent replaces traditional mechanical position feedback linkages with a direct shaft coupling system. The position feedback shaft is directly coupled to the output shaft of the gear interface, eliminating intermediate mechanical linkages that cause torsion and stiffness errors. This substitution maintains the necessary mechanical power transmission while dramatically improving position measurement accuracy.
3Reliability
If the electric motor is positioned externally to avoid high temperatures, then component reliability is improved, but the actuation system complexity increases with extended shafts and external positioning
Solution Approach 1:
The shafts serve multiple functions simultaneously: they transmit rotational motion from the motor to the gear interface, provide mechanical support, enable position feedback transmission, and seal the boundary between internal and external environments. This multi-functionality reduces the need for separate components and simplifies the overall structure despite the external motor positioning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration maintains accurate position feedback and control while avoiding high-temperature effects, enhancing actuation bandwidth and responsiveness by keeping critical components outside the high-temperature zone, thus improving the reliability and precision of the actuation system.
Implementation Method 1
an electric motor coupled to a drive shaft that extends to align a gear interface of the electric actuator with, when mounted in the gas turbine engine, a variable geometry adjustment interface of the gas turbine engine
Implementation Method 2
a rotational position sensor coupled to a motor end of the position feedback shaft proximate the electric motor
Data Source
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AI summary
An electric actuator (112) for control of an engine includes an electric motor coupled to a drive shaft (204) that extends to align a gear interface (140) of the electric actuator with a variable geometry adjustment interface of the engine. A position feedback shaft (206) extends coaxially with respect to the drive shaft. The position feedback shaft is coupled to an output shaft of the gear interface (140) at a gear interface end of the position feedback shaft. A rotational position sensor is coupled to a motor end of the position feedback shaft proximate the electric motor. The drive shaft (204) and the position feedback shaft (206) are sized to position an output ring gear (218) of the output shaft in contact with the variable geometry adjustment interface within a casing of the engine and to further position the electric motor and the rotational position sensor external to the casing of the engine.