Turbomachine Accessory Gearbox Shear Bracket Alignment Pin
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Solution Overview
Problem
Mounting accessory gearboxes to turbomachines is challenging due to vibrations and the heavier weight of land-based turbomachine gearboxes, which complicates the process and can lead to increased stresses on the gearbox housing.
Innovation Solution
A gearbox assembly that includes a shear bracket connectable to a housing structure with a support pin extending along a longitudinal axis, allowing axial movement and supported by a hanger attached to the turbomachine, along with a spherical bearing and bushing for rotational support, which reduces stresses and accommodates thermal growth and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If accessory gearbox is mounted directly to turbomachine case, then structural support is provided, but vibrations and heavy weight cause increased stresses and mounting difficulty
Solution Approach 1:
The patent introduces a shear bracket as an intermediary component between the accessory gearbox and the turbomachine case. This shear bracket absorbs and redistributes the stresses, reducing the attachment stresses on the housing while maintaining structural support. The shear bracket acts as a mediator that decouples the direct stress transmission path from the heavy gearbox to the turbine case.
Solution Approach 2:
The support pin is designed to be movable axially relative to the shear bracket, introducing dynamic flexibility to the mounting system. This allows the gearbox assembly to accommodate vibrations and thermal growth by permitting controlled movements, thereby reducing stress concentrations while maintaining structural integrity during operation.
2Power
If heavier land-based accessory gearbox is used, then increased power transmission capability is achieved, but mounting complexity and difficulty increase
Solution Approach 1:
The mounting system is segmented into distinct functional components: the shear bracket for stress management, the movable support pin for positioning and vibration accommodation, and the spherical bearing for rotational support. This segmentation allows each component to be optimized independently for its specific function, simplifying the overall mounting process despite the heavy gearbox weight.
Solution Approach 2:
The patent changes the mounting parameters from rigid fixed-position attachment to a system with controlled degrees of freedom. The support pin allows axial movement and the spherical bearing permits rotational movement, transforming the mounting system from statically rigid to dynamically adaptable, thereby simplifying installation and reducing stress on heavy land-based gearboxes.
3Measurement precision
If rigid mounting is used, then positional control is maintained, but vibrations and thermal growth cause increased stresses
Solution Approach 1:
The support pin is designed with axial movability relative to the shear bracket, and the spherical bearing allows rotational movement. This dynamic mounting system maintains positional control through the constrained degrees of freedom while accommodating vibrations and thermal growth, preventing stress concentrations that would occur with completely rigid mounting.
Solution Approach 2:
The movable support pin and spherical bearing configuration explicitly accommodates thermal expansion and growth of the gearbox and turbine components during operation. The system allows for controlled movement in response to thermal effects while maintaining adequate positional control, preventing stress buildup from constrained thermal expansion.
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 effectively reduces stresses on the gearbox housing by allowing relative movement between components, maintaining positional control and securing the gearbox with six degrees of freedom, thereby simplifying the mounting process and reducing attachment stresses.
Implementation Method 1
The spherical bearing receives the support pin. The spherical bearing is held within an aperture of the shear bracket.
Implementation Method 2
The bushing interfaces directly with the support pin and is rotatable about the longitudinal axis relative to the support pin.
Data Source
AI summary
An exemplary gearbox assembly includes a shear bracket connectable to a flange of a housing structure, and a support pin extending along a longitudinal axis, the support pin supporting the shear bracket relative to a turbomachine, the shear bracket moveable axially relative to the support pin.