One-Way Pitch Lock for Hydraulic Failure Blade Control
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Solution Overview
Problem
In gas turbine engines, the failure of the hydraulic pitch actuator system can cause centrifugal twisting moments to inadvertently change the pitch of fan blades to the fine direction, leading to increased drag and operational inefficiencies, which existing systems fail to prevent effectively.
Innovation Solution
A mechanical pitch lock system utilizing a one-way clutch or roller elements is integrated with the hydraulic linear actuator, which engages only in the fine pitch direction to prevent axial motion when hydraulic pressure drops, ensuring the blades maintain their coarse pitch setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a hydraulic pitch actuator system is used to control fan blade pitch, then the blades can be adjusted to optimal pitch angles for performance, but hydraulic failure causes uncontrolled movement to fine pitch position increasing drag
Solution Approach 1:
The patent converts the harmful effect of hydraulic failure (uncontrolled fine pitch movement) into a beneficial outcome by designing a pitch lock system that automatically engages upon hydraulic pressure loss. The one-way clutch mechanism transforms the uncontrolled movement force into a locking action, preventing drag increase and maintaining engine performance during failure conditions.
Solution Approach 2:
The pitch lock system acts as an intermediary mechanism between the hydraulic actuator and the blade pitch control. This intermediate device monitors hydraulic pressure and mechanically intervenes when pressure is lost, blocking the connection between the actuator and pitch control to prevent unwanted blade movement while allowing normal operation when hydraulic pressure is present.
2Reliability
If a mechanical pitch lock system with one-way clutch is added, then pitch control stability during hydraulic failure is improved, but device complexity increases
Solution Approach 1:
The patent merges the pitch lock function with the existing hydraulic actuator components by integrating the one-way clutch mechanism into the actuator's structural elements. The clutch plates, springs, and housing are combined with the actuator's piston, rod, and chamber structure, creating a unified system that reduces overall complexity compared to a separate pitch lock device.
Solution Approach 2:
The pitch lock system is designed to be self-activating through the one-way clutch mechanism that automatically engages when hydraulic pressure is lost. The spring-loaded clutch plates self-adjust based on pressure conditions without requiring external control signals or additional actuators, reducing system complexity while maintaining reliability.
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 mechanical pitch lock system effectively prevents the blades from moving to the fine pitch position during hydraulic failures, maintaining efficiency and reducing drag by locking the pitch actuator in the coarse position, thus enhancing engine performance.
Implementation Method 1
A mechanical pitch lock system utilizing a one-way clutch or roller elements is integrated with the hydraulic linear actuator, which engages only in the fine pitch direction to prevent axial motion when hydraulic pressure drops
Implementation Method 2
A mechanical pitch lock system utilizing a one-way clutch or roller elements is integrated with the hydraulic linear actuator
Implementation Method 3
A mechanical pitch lock system utilizing a one-way clutch or roller elements is integrated with the hydraulic linear actuator
Data Source
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AI summary
A pitch lock system (200, 400) including an outer member (204, 206, 318) having a centerline axis (12, 112, 312), an inner member (210, 405) located radially inward of the outer member (204, 206, 318) with respect to the centerline axis (12, 112, 312), and a plurality of clutch elements (208, 402, 404) located between the outer member (204, 206, 318) and the inner member (210, 405). The pitch lock system (200, 400) has a disengaged position (1200) and an engaged position (1300, 1400). In the engaged position (1300, 1400), the plurality of clutch elements (208, 402, 404) are constrained between the inner member (210, 405) and the outer member (204, 206, 318) such that relative axial direction of the plurality of clutch elements (208, 402, 404) is permitted in only one direction. An engine (10) includes a pitch actuator (58, 66) and the pitch lock system (200, 400).