Variable Pitch Rotor Blade Dual Support Retention
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Solution Overview
Problem
Standard rotor blades in aircraft propulsion systems face challenges in maintaining pitch control due to substantial centrifugal and aerodynamic forces, leading to potential overspeed conditions and blade loss, especially in variable pitch systems without adequate countermeasures.
Innovation Solution
The design incorporates dual support members attached to the airfoil of rotor blades, allowing for variable pitch control through a hub assembly with a collector ring and bearing mechanism, reducing the need for counterweights and enhancing structural integrity with lightweight materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If standard rotor blade configurations with ball/roller bearing and flex member are used, then pitch change capability is achieved, but the mechanism becomes extremely heavy to accommodate centrifugal forces
Solution Approach 1:
The rotor blade is divided into two independent support members (first and second support members) attached at different locations on the airfoil. Each support member independently handles portion of the centrifugal and aerodynamic loads, allowing the use of lighter retention mechanisms compared to a single heavy mechanism.
Solution Approach 2:
The patent eliminates the need for counterweights by using the dual support member configuration that naturally balances the centrifugal forces through proper geometric arrangement and attachment points, reducing the overall weight of the retention system.
2Strength
If heavy retention mechanisms are used to accommodate centrifugal forces, then structural integrity is improved, but the device complexity increases
Solution Approach 1:
The retention system is segmented into two separate support members with their own retention mechanisms, allowing each component to be optimized for its specific load conditions rather than requiring a single overly complex heavy-duty mechanism.
Solution Approach 2:
Each support member is designed with specific geometric characteristics and attachment configurations tailored to the local stress conditions at its attachment point on the airfoil, optimizing structural integrity while minimizing overall complexity.
3Stability of the object's composition
If pitch control system exerts force to overcome total twisting moment, then blade pitch stability is maintained, but the system requires substantial control forces that can lead to overspeed conditions during malfunction
Solution Approach 1:
The dual support members are positioned asymmetrically on the airfoil structure, creating an inherent mechanical balance that reduces the total twisting moment requiring active control, thereby reducing the risk of overspeed during control system malfunction.
Solution Approach 2:
The geometric arrangement of the two support members creates a natural balancing effect that counteracts the centrifugal twisting moment, reducing the burden on the pitch control system and providing inherent protection against overspeed conditions.
4Stability of the object's composition
If counterweights are added to prevent pitch tendencies, then pitch control is improved, but the rotor blade weight increases and loading on bearings increases
Solution Approach 1:
The patent replaces traditional counterweights with a dual support member configuration that achieves pitch stability through geometric arrangement and load distribution, eliminating the need for additional counterweight mass.
Solution Approach 2:
The support members are designed with specific geometric parameters and attachment configurations that inherently balance the centrifugal forces, achieving pitch control without adding mass through counterweights.
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 efficiently balances high centrifugal forces, reduces the risk of overspeed and blade loss, and allows for controlled pitch adjustments to optimize thrust and efficiency across varying operating conditions, eliminating the need for counterweights and minimizing mechanical stress.
Implementation Method 1
allow pitch change of the blade with relatively low friction between components
Implementation Method 2
accommodate the substantial centrifugal forces exerted on the mechanisms during operation
Implementation Method 3
The CTM, which is typically the most substantial of the forces, originates from a non-symmetrical mass distribution of an airfoil of a rotor blade about a pitch change axis of the airfoil
Implementation Method 4
The ATM is caused when the effective center of pressure on each section of an airfoil of a rotor blade is forward or aft of the pitch change axis
Implementation Method 5
the pitch control system of a typical rotor blade device exerts a torsional load in the direction of increased pitch to hold the blade pitch constant
Implementation Method 6
The FTM resists turning motion and develops in retention bearings that support the rotor blade due to high centrifugal loads acting on the bearings
Data Source
AI summary
A propulsive thrust device for an engine includes a rotor blade and a hub assembly on which the rotor blade is mounted. The rotor blade comprises an airfoil and at least two support members. A propeller thrust device includes a rotor blade, a central hub at which the rotor blade centrifugal load is supported, and an outer hub supporting a control mechanism mechanically connected to the rotor blade and controllable to vary the pitch of the rotor blade on the central hub. A rotor blade for an aircraft engine or in a separate ducted fan housing driven by a powered shaft or gearbox output shaft includes an airfoil and first and second support members attached to the airfoil. An extended arm or portion of the structure at the root of the airfoil of each blade is attached to a controllable mechanism that can vary the pitch of all blades simultaneously.