Variable-Pitch Vane Control Device for Aircraft Engines
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Solution Overview
Problem
Existing control systems for variable-pitch vanes in turbo-engines face significant hysteresis issues due to temperature variations and kinematic forces, leading to precision problems in pitch control, which are exacerbated by the deformation of rigid control rings.
Innovation Solution
A control device featuring an annular row of actuating levers with articulated links that allow for deformation absorption, including a ball-joint connection to prevent hyperstaticity, and a dual series of links to enhance resistance and flexibility, minimizing mass and maximizing precision in pitch control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid control ring is used to control the pitch of vanes, then the structural strength is improved, but the hysteresis and deformation errors increase due to temperature variations and kinematic forces
Solution Approach 1:
The control ring is divided into multiple articulated links (at least three links per lever) that are connected through pivot connections. This segmentation allows each link to deform independently, absorbing thermal expansion and kinematic forces while maintaining overall structural integrity and precise control of the vane pitch.
Solution Approach 2:
The control mechanism transitions from a rigid structure to a flexible articulated structure that can change its configuration parameters (angles between links) in response to temperature variations and forces, thereby maintaining precision without requiring increased size or mass.
2Reliability
If the size of the control ring is increased to counteract deformation effects, then the reliability is improved, but the mass of the system increases
Solution Approach 1:
By segmenting the control ring into articulated links, the system achieves improved reliability through flexibility and deformation absorption without increasing the overall size or mass. The segmented structure adapts to thermal and mechanical variations within the existing footprint.
Solution Approach 2:
The control mechanism becomes dynamic rather than static, with links that can rotate and adjust their configuration in response to varying conditions. This dynamic adaptation improves reliability without requiring a larger, heavier structure.
3Measurement precision
If articulated links are used to absorb deformations, then the pitch control precision is improved, but the device complexity increases
Solution Approach 1:
The control ring is segmented into articulated links connected by pivot connections, creating a mechanism that absorbs deformations through controlled articulation rather than complex active control systems. This passive flexibility improves precision while maintaining relatively simple mechanical components.
Solution Approach 2:
The system uses passive parameter changes (angular configurations of links) to adapt to varying conditions, eliminating the need for complex active control mechanisms while maintaining high pitch control precision.
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 ensures precise follow-through of the pitch law according to engine speed while minimizing system mass, effectively reducing hysteresis and deformation-related errors, thereby improving the reliability and efficiency of the pitch control mechanism.
Implementation Method 1
the pivot connection is connected to the second ends of the levers and rigidifies the series of links to form a ring in the radial plane, transverse to the axis and passing through the ends of the levers, while leaving a degree of freedom of deformation in this plane in order to absorb shape irregularities or deformations with respect to the circumference
Data Source
AI summary
The present disclosure relates to a control device of an annular row of variable-pitch vanes for an aircraft engine. The device may include an annular row of actuating levers which each may include a first end attached to a pivot of one of the vanes and a second end connected to a control ring in rotation about an axis of rotation. The control ring may include at least one annular series of articulated links, wherein the second end of each lever carries a pivot connection articulating two successive links of the annular series about a single axis, the single axis extending in a direction substantially parallel to the axis of rotation.