Cylindrical Rod Clamping for Turbomachine Vane Positioning
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Solution Overview
Problem
Existing variable-pitch vane control systems in turbomachines suffer from inaccuracies in positioning due to manufacturing tolerances, leading to slack in the connection between the control rod and the vane pivot, which affects the overall operation of the assembly.
Innovation Solution
A variable-pitch vane control device with a substantially cylindrical rod that is clamped securely within a bore in the vane pivot using clamping means, eliminating slack and ensuring precise positioning without additional parts, and featuring a minimal number of components for ease of assembly and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a control rod with a threaded end and nut is used to connect the rod to the vane pivot, then the connection can be assembled, but manufacturing tolerances create slack and positioning inaccuracy ranging from 0.5° to 0.7°
Solution Approach 1:
The rod is pre-positioned in the bore of the vane pivot before final clamping. The clamping means are then activated to secure the rod in its predetermined position, eliminating the need for post-assembly adjustment and preventing slack caused by manufacturing tolerances.
Solution Approach 2:
The connection method transitions from a threaded mechanical fastening (with inherent clearance and tolerance accumulation) to a clamping mechanism that applies radial force to eliminate gaps. The clamping force transforms the connection state from loose to tight, removing positioning inaccuracy without requiring high-precision machining.
2Adaptability or versatility
If traditional hinge connections with multiple parts are used to accommodate movements between the ring and rod, then the connection can absorb relative movements, but the device complexity increases and positioning accuracy decreases
Solution Approach 1:
The clamping means integrate multiple functions into a single mechanism: they secure the rod to the pivot, accommodate radial movements, and maintain positioning accuracy simultaneously. This merging eliminates the need for separate hinge components while preserving adaptability to relative movements.
Solution Approach 2:
The clamping mechanism serves multiple purposes: it fastens the rod to the pivot, allows for the necessary relative movements between components, and maintains precise positioning. This multi-functional design replaces several specialized parts with a single versatile clamping system.
3Ease of manufacture
If a rigid rod with traditional fastening methods is used, then the rod can be manufactured, but the rod may suffer from twisting movements and reduced lifetime
Solution Approach 1:
The traditional threaded mechanical fastening system is replaced with a clamping mechanism that distributes stress more evenly along the rod surface. This substitution eliminates stress concentration points that would initiate fatigue cracks, thereby extending the rod's service life while maintaining ease of manufacture.
Data Source
AI summary
A variable-pitch control device for a turbomachine compressor is disclosed. The device includes a rod, a fastening device for fastening a first end of the rod to a pivot of a vane to be controlled, and a connection device between a second end of the rod and a control ring. The rod is substantially cylindrical, its first end being engaged in a bore in the pivot of the vane. The device further includes a clamping device for clamping the first end of the rod in the bore in the pivot in order to fasten it to the pivot.