Electrohydraulic Pitch Setting With Reversible Pump for Leak Reduction
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Solution Overview
Problem
Existing turbomachine pitch change mechanisms are complex, fragile, prone to oil leaks, and dependent on hydraulic systems, leading to reliability issues and performance limitations, especially at low speeds and during flight maneuvers, and require additional safety systems to prevent blade locking.
Innovation Solution
A passive electrohydraulic actuator system with dual hydraulic pumps and a pumping assembly that operates independently of electrical control, using a closed hydraulic circuit to adjust propeller pitch, eliminating the need for rotating oil transfer and reducing dependency on hydraulic fluid pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional hydraulic pitch change mechanism with OTB is used, then pitch variability is achieved, but the system becomes complex and fragile with significant oil leaks
Solution Approach 1:
The patent extracts and eliminates the OTB (oil transfer bearing) from the hydraulic pitch change mechanism. By removing this complex rotating seal component, the system achieves pitch variability through a simplified hydraulic circuit that uses a reversible pump mounted on the propeller shaft, directly eliminating the source of oil leaks and mechanical fragility while maintaining blade pitch control capability
Solution Approach 2:
The patent introduces a reversible hydraulic pump as an intermediary device mounted on the propeller shaft. This pump serves as a mediator between the electric motor and the pitch change mechanism, providing hydraulic fluid in both directions of rotation to control blade pitch without requiring complex rotating seals or external hydraulic connections
2Adaptability or versatility
If a conventional hydraulic pitch change mechanism with OTB is used, then pitch variability is achieved, but oil leaks affect reliability and performance
Solution Approach 1:
The patent removes the OTB (oil transfer bearing) from the system, which is identified as the primary source of oil leaks. By eliminating this rotating seal component that requires precise alignment and maintenance, the system achieves pitch control while significantly improving reliability and eliminating the fragility associated with complex rotating hydraulic seals
3Power
If a non-reversible hydraulic pump is used, then hydraulic fluid delivery is achieved, but a flow reversing valve and electrical control system are required
Solution Approach 1:
The patent inverts the conventional approach by using a reversible pump that can deliver hydraulic fluid in both directions of rotation, eliminating the need for flow reversing valves and complex electrical control systems. The pump's reversible nature allows direct mechanical control through the propeller shaft rotation direction, simplifying the overall control architecture
4Reliability
If the lubrication unit is linked to turbomachine operation, then lubrication is provided, but auxiliary protection systems are needed for overspeed or shutdown
Solution Approach 1:
The patent implements a self-service protection system where the reversible pump and hydraulic circuit automatically respond to turbomachine operational states. The system uses the direction of propeller shaft rotation to automatically control pitch, providing inherent protection against overspeed and shutdown conditions without requiring external auxiliary protection 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 system enhances turbomachine reliability by minimizing oil leaks and oversizing, operates independently of hydraulic fluid pressure, and ensures safe pitch adjustment without electrical control, facilitating feathering and pitch change across various flight conditions.
Implementation Method 1
The variation in the delivered hydraulic fluid pressure and the distribution of the fluid in one or other of the cylinder chambers make it possible to vary the pitch of the blades
Implementation Method 2
an electric motor controlled and supplied with current by a current generator
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
The present invention relates to a mechanism for changing the pitch of a propeller (13) of a turbine engine, the mechanism comprising an electrohydraulic actuator (11) that comprises: - an electric machine comprising a rotatable actuator shaft; - a pumping assembly comprising two hydraulic axial piston pumps, each comprising: o a barrel housed in a cavity filled with hydraulic fluid; o a set of cylinders formed in the barrel, each cylinder housing a translatable piston and comprising an inlet port and a delivery port; o and an inclined plate, the plate of a first pump comprising a crescent-shaped inlet port for circulating the hydraulic fluid when the plate is rotated in a first direction, and the plate of a second pump comprising a crescent-shaped inlet port for circulating the hydraulic fluid when the plate is rotated in a second direction.