Turboprop Variable-Pitch Propeller External Actuation
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Solution Overview
Problem
Conventional turboprop systems with internal mechanical blade pitch control mechanisms are heavy, expensive, and difficult to maintain due to their complex and centralized design.
Innovation Solution
The implementation of an external mechanical control system using epicyclic mechanisms and actuator annuli positioned between the stationary casing and rotary supports, allowing for variable blade pitch adjustment through a gearwheel and actuator system that reduces the need for internal mechanical components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal mechanical control mechanisms are used on the turbine axis, then blade pitch control is achieved, but the system becomes heavy, expensive, and difficult to maintain
Solution Approach 1:
The control mechanism is extracted from the internal turbine axis location and relocated to the external periphery of the rotary support. This removes the heavy intermediate mechanical transmission devices from the core engine structure, significantly reducing the weight of the control system while maintaining blade pitch control functionality through direct external actuation of the control annulus.
Solution Approach 2:
An epicyclic gear mechanism serves as an intermediary between the stationary actuator and the rotating blade pitch control system. This intermediary mechanism enables power transmission from the stationary external actuator to the rotating blades without requiring heavy internal mechanical linkages, resolving the contradiction between control reliability and system weight.
2Reliability
If internal mechanical control mechanisms are used on the turbine axis, then blade pitch control is achieved, but manufacturing and maintenance costs increase
Solution Approach 1:
The control mechanism is extracted from the complex internal turbine axis environment and placed in the external periphery where access for manufacturing and maintenance is significantly improved. This relocation simplifies the manufacturing process by allowing standard actuator components to be installed from the outside and facilitates routine maintenance operations without requiring engine disassembly.
Solution Approach 2:
The epicyclic gear mechanism acts as an intermediary that bridges the stationary external actuator and the rotating blade system. This intermediary design uses standardized gear components that are easier to manufacture and replace compared to custom internal mechanical linkages, reducing both manufacturing and maintenance costs.
3Reliability
If internal mechanical control mechanisms are used on the turbine axis, then blade pitch control is achieved, but the system becomes complex and difficult to maintain
Solution Approach 1:
The control mechanism is extracted from the confined internal turbine axis space and relocated to the external periphery of the rotary support. This extraction provides ample space for maintenance personnel to access, inspect, and repair control components from the outside, dramatically improving ease of repair while maintaining control reliability through the robust epicyclic gear design.
4Weight of moving object
If external control mechanisms are used between the stationary casing and rotary support, then the control system is simplified and weight is reduced, but the mechanism complexity increases
Solution Approach 1:
The epicyclic gear mechanism serves as an intermediary that, while adding a layer of mechanical complexity, enables the use of lighter external actuators compared to internal mechanical linkages. The epicyclic gears provide compact power transmission in a rotating reference frame, allowing weight reduction through external actuator placement while managing complexity through a well-established mechanical principle.
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 solution simplifies the control mechanism, reduces weight and maintenance costs, and allows for efficient adaptation of engine power to operational conditions by external actuation of blade pitch, enhancing the turboprop's performance and reliability.
Implementation Method 1
via a first epicyclic mechanism carried by said first rotary support
Implementation Method 2
each blade pin carrying a gearwheel meshing with a first actuator annulus forming a toothed wheel
Data Source
AI summary
A turboprop having at least one propeller formed by a set of variable pitch blades. Each blade is swivel-mounted on a rotary support and carries a gearwheel meshing with an actuator annulus rotating on the rotary support and coupled to a control annulus via an epicyclic mechanism.