Variable Stator Vane Control System Using Roller-Groove Intermediary
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Solution Overview
Problem
Existing control systems for variable-pitch blade stages in turbomachines are limited in reproducing complex control laws, particularly those with sinusoidal portions, as they only allow for simple, progressively sloping correlation curves.
Innovation Solution
A control system that includes an additional pivoting member with a roller sliding in a groove, which compensates for deviations between desired and nominal setting laws, enabling the reproduction of any type of blade setting law, including complex ones with sinusoidal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional control system with control ring and links is used, then the structure is simple and easy to manufacture, but it can only produce progressively sloping correlation curves and cannot reproduce complex control laws with sinusoidal portions
Solution Approach 1:
An additional pivoting member is introduced as an intermediary element between the follower member and the follower ring. This member includes a roller that travels along a specifically shaped groove, acting as a mediator that transforms the simple rotational motion into complex blade setting patterns, enabling reproduction of sinusoidal and other complex control laws while maintaining the overall mechanical control system architecture
Solution Approach 2:
The groove in which the roller travels is given a specific curved shape that corresponds to the desired complex control law. By designing the groove with appropriate curvature and geometry, the system can reproduce complex correlation curves including sinusoidal portions, transforming the path of the roller into the desired blade setting pattern
2Manufacturing precision
If the control system is simplified for ease of manufacture, then production cost decreases, but the system cannot achieve precise trajectory compensation between desired and nominal setting laws
Solution Approach 1:
The additional pivoting member with roller and groove serves as a dedicated intermediary mechanism for trajectory compensation. It isolates the complex precision requirement into a separate, specialized component that can be manufactured and calibrated independently, allowing the rest of the control system to remain relatively simple while achieving high precision in the critical trajectory compensation function
3Measurement precision
If traditional control systems are used, then the device complexity is low, but the control precision for complex aerodynamic requirements is insufficient
Solution Approach 1:
The groove geometry is specifically designed with precise curved contours that directly determine the blade pitch angle trajectory. By shaping the groove to match the desired correlation curve, the system achieves high measurement and control precision for complex aerodynamic requirements, as the roller's position along the groove directly translates to precise blade angle positioning
Data Source
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Figure 2A
Figure 2B
AI summary
A two-stage (10, 10') variable-pitch turbomachine stator blade (14, 14') control system, comprising a drive element (24) for rotating the control ring (22) of one of the stages (10) via a pilot member (26) pivotally mounted on the housing (12), a synchronizing bar (30) for transmitting the rotational motion of the driven ring (22) from the drive element (24) to the control ring (22') of the other stage (10') via a follower member (26') pivotally mounted on the housing, and an additional pivoting member (44) interposed between the follower member (26') and the follower ring (22'), said additional pivoting member being pivotally mounted on the follower member (26') and connected to the housing (12) by a roller (46) sliding in a groove (48) integral with the housing.