Turbine Blade Rack Control via Radial Sliding Guides
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Solution Overview
Problem
Existing control systems for pivotally-mounted blades in turbine engines face challenges in efficiently controlling all blades due to space constraints and high operational temperatures and speeds, particularly when using bevel gears inside a polygonal ring, which limits their effectiveness.
Innovation Solution
An actuator ring with racks that mesh with the blades' teeth, allowing for precise angular positioning, where the racks are mounted on the ring with guides that enable sliding movements to maintain accurate meshing and resist centrifugal and thermal expansions, ensuring reliable operation across a wide range of temperatures and speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If bevel gears are arranged inside the polygonal ring to control blade angular positions, then the control mechanism is compact, but it becomes difficult or impossible to control all blades due to space constraints
Solution Approach 1:
The patent moves the control mechanism from the interior of the polygonal ring to its exterior periphery. Racks are mounted on the outer circumference of the ring, allowing each rack to engage with corresponding teeth on each blade independently. This dimensional relocation resolves the space constraint problem by utilizing the available peripheral space around the ring rather than the confined interior volume.
2Device complexity
If racks are rigidly fixed to the ring, then the structure is simple, but thermal expansion and centrifugal forces at high speeds cause deformation and loss of accurate meshing
Solution Approach 1:
The patent transitions from a rigid fixed connection to a dynamic adjustable connection. Each rack is mounted on the ring via mounting means that allow relative movement in the radial direction. This dynamic mounting enables the racks to self-adjust their positions radially in response to thermal expansion and centrifugal forces, maintaining accurate tooth meshing despite environmental changes and high-speed operation.
3Area of stationary object
If the control device is located downstream from the blade support ring, then it has more space, but it occupies a larger volume and is less efficient
Solution Approach 1:
The patent utilizes the peripheral dimension of the ring structure rather than moving downstream. By mounting racks on the outer circumference of the ring, the design achieves both compact positioning (maintaining control efficiency) and adequate space (utilizing peripheral area). This eliminates the need to relocate downstream while still providing sufficient mounting space for all racks.
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 allows for reliable and efficient control of blade angular positions with minimal volume occupation, maintaining accurate tooth pitch and resisting deformation, thus ensuring durable operation under high-speed and high-temperature conditions.
Implementation Method 1
resisting centrifugal and thermal expansions
Implementation Method 2
resisting centrifugal and thermal expansions
Implementation Method 3
suitable for sliding firstly relative to the ring along the radial direction specific to each guide, and secondly relative to the rack along a movement direction that is substantially radial and specific to the rack
Data Source
AI summary
An assembly in a turbine engine for controlling plural toothed pivotally-mounted blades arranged in azimuth around the axis of the turbine engine and including an actuator ring controlling a position of the blades. Racks mounted on the ring present corresponding sets of teeth meshing with the set of teeth of a respective one of the blades to place it in a selected angular position, and they are held in the radial direction by radial positioning mechanism fastened to the blade. Each rack is mounted on the ring by plural guides spaced apart circumferentially around the ring, that connect together movements of the rack and of the ring in the circumferential direction, and that are configured to slide relative to the ring, for each guide in its own radial direction, and relative to the rack in a direction of movement that is substantially radial and specific to the rack.