Variable Propeller Drive With Sprag Clutch for Hybrid Gas Turbines
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Solution Overview
Problem
Hybrid-electric gas turbine engines face complexity, mass, and expense issues due to generators, motors, and drive elements, which contribute to increased engine complexity and weight.
Innovation Solution
A variable drive arrangement using a sprag clutch and gear connections that passively couples and decouples the motor to the propeller based on torque inputs, allowing efficient power distribution with reduced mass and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hybrid-electric architecture with motors, generators, and drive elements is incorporated, then power redistribution capability and operating efficiency are improved, but device complexity and mass increase
Solution Approach 1:
The sprag clutch is designed to perform multiple functions: it acts as a passive coupling mechanism that automatically engages the motor with the propeller during motor-driven operation, and automatically disengages during engine-driven operation. This single component replaces what would otherwise require multiple active clutches and control systems, reducing overall drive system complexity while maintaining hybrid power redistribution capability
Solution Approach 2:
The sprag clutch operates passively without requiring external control signals, actuators, or power sources. It automatically couples and decouples the motor based on the direction of torque flow between the engine spool and propeller, eliminating the need for complex active control systems and reducing device complexity
2Adaptability or versatility
If hybrid-electric architecture with motors, generators, and drive elements is incorporated, then power redistribution capability and operating efficiency are improved, but mass increases
Solution Approach 1:
The sprag clutch serves multiple functions within a single compact component: it provides passive coupling, passive decoupling, and torque direction sensing. This multi-functionality eliminates the need for separate active clutches, actuators, and control mechanisms that would otherwise be required, thereby reducing the overall mass of the hybrid drive system while maintaining full power redistribution capability
3Device complexity
If passive coupling mechanism with sprag clutch is used, then device complexity is reduced, but control precision over motor engagement may be limited
Solution Approach 1:
The sprag clutch automatically senses the direction of torque flow and adjusts its engagement state accordingly. When torque flows from the engine spool to the propeller, the clutch passively disengages the motor. When torque flows from the motor to the propeller, the clutch passively engages the motor. This self-service mechanism provides precise control of motor engagement without requiring external sensors, actuators, or control systems
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
The solution provides efficient hybrid power distribution with reduced drivetrain complexity and mass, enhancing the operational efficiency and reliability of gas turbine engines.
Implementation Method 1
a sprag clutch rotationally coupled to the first gear connection. The sprag clutch is configured to passively decouple the motor from the first gear connection when a torque input from the engine spool exceeds a torque input from the motor, and is configured to passively couple the motor to the first gear connection when the torque input from motor exceeds a torque input from the engine spool
Data Source
AI summary
A gas turbine engine includes an engine spool with a turbine section, a propeller, a motor, and a variable drive arrangement. The variable drive arrangement mechanically couples the engine spool to the propeller, and includes a first gear connection rotationally coupled to the propeller, a second gear connection rotationally coupled to the engine spool, and a sprag clutch rotationally coupled to the first gear connection. The sprag clutch is configured to passively decouple the motor from the first gear connection when a torque input from the engine spool exceeds a torque input from the motor, and is configured to passively couple the motor to the first gear connection when the torque input from motor exceeds a torque input from the engine spool.