Axial Link Mechanism for Variable Stationary Blade Driving
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Solution Overview
Problem
Existing link mechanisms for variable vanes in gas turbines and turbo machines face difficulties in assembly and disassembly due to the need for a large working space and high force requirements for inserting and removing detent pins, which leads to interference with adjacent mechanisms and increased operational time.
Innovation Solution
A link mechanism with a pin hole formed parallel to the axis, allowing for axial insertion and removal of detent pins using a pushing bolt for attachment and a removing bolt for detachment, which secures sufficient working space and reduces the force needed for assembly and disassembly, preventing pin damage from rotational torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the detent pin insertion direction is perpendicular to the rotary shaft axis, then the link mechanism can be compact in the axial direction, but a large working space is needed in the radial direction which interferes with adjacent mechanisms
Solution Approach 1:
The patent inverts the conventional detent pin insertion direction from radial (perpendicular to shaft axis) to axial (parallel to shaft axis). This inversion allows the detent pin to be inserted and removed in the axial direction, utilizing the existing axial working space between the link member and casing, thereby eliminating the need for additional radial working space and avoiding interference with adjacent link mechanisms.
2Stability of the object's composition
If the detent pin and pin hole form an interference fit, then the link member is securely non-rotatable with respect to the rotary shaft, but large force is needed to insert and remove the detent pin
Solution Approach 1:
The patent segments the detent pin structure into two functional parts: a fitting portion that forms an interference fit with the pin hole for rotational stability, and a threaded portion that engages with a threaded hole in the link member for secure attachment. This segmentation allows the detent pin to achieve both rotational stability and ease of installation/removal, as the threaded connection enables simple screw-in and screw-out operations without requiring large insertion forces.
3Reliability
If the detent pin is inserted with large force to achieve interference fit, then reliable connection is obtained, but the pin may be damaged due to rotational torque during operation
Solution Approach 1:
The detent pin is segmented into a fitting portion for interference engagement and a threaded portion for screw connection. The threaded portion engages with a threaded hole in the link member, creating a secure mechanical connection that can withstand rotational torques during operation without damaging the pin. This segmentation allows the interference fit to be achieved with moderate force while the threaded connection provides the necessary strength to handle operational loads.
Solution Approach 2:
The threaded connection is established before the detent pin is fully inserted into the pin hole. By first securing the detent pin to the link member through threading, the connection is pre-established in a controlled manner, preventing damage from excessive insertion forces. The interference fit is then achieved as the detent pin is gently pushed into the pin hole, with the threaded connection already providing structural support.
Data Source
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AI summary
This link mechanism is provided with a rotating shaft on which a pin pushing screw hole is formed, a link member on which a shaft insertion hole through which the other end of the rotating shaft can be inserted is formed, an anti-rotation pin for restraining the link member such that the link member cannot rotate about the axial line relative to the other end of the rotating shaft, a pin support member to which the anti-rotation pin is secured, and a pin pressing bolt having a male screw part that can screw into the pin pushing screw hole, wherein a pin hole into which the anti-rotation pin can be inserted is formed on the other end of the rotating shaft and the link member, a pin extraction screw hole is formed on the pin support member, and the diameter of the screw thread of the pin extraction screw hole is larger than the diameter of the screw thread of the male screw part on the pin pushing bolt and is smaller than the outer diameter of the bolt head of the pin pushing bolt.