Gas Turbine Accessory Drive Gearbox Weight Reduction
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Solution Overview
Problem
Existing accessory drive gearboxes for gas turbines are excessively large and heavy due to inefficient positioning and distribution of accessories, which complicates the design and increases size and weight.
Innovation Solution
A gearbox configuration with two gear trains, each using fewer toothed wheels to drive multiple accessories, along with a conical power transmission shaft and optimized accessory placement to reduce weight and size, while maintaining balanced weight distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional accessory drive gearboxes use separate gear trains for each accessory, then each accessory can be driven independently, but the size and weight of the gearbox become excessive
Solution Approach 1:
The patent merges multiple separate gear trains into a single integrated gear train structure. Instead of having separate gear trains for each accessory, the invention uses one gear train with multiple toothed wheels that can drive different accessories through a common power transmission shaft, thereby reducing the overall number of components and the total weight of the gearbox.
Solution Approach 2:
The power transmission shaft serves multiple functions simultaneously. It acts as the common drive shaft for the gear train and also as the drive shaft for accessories like the hydraulic pump and centrifugal compressor. This multi-functionality reduces the need for separate drive shafts and gear trains, thereby reducing weight while maintaining independent drive capability for each accessory.
2Ease of operation
If traditional gearboxes position accessories separately for each drive shaft, then each accessory has dedicated space, but the overall volume and size increase
Solution Approach 1:
The invention transitions from a one-dimensional linear arrangement of accessories along the power transmission shaft to a three-dimensional distributed arrangement. Accessories are positioned at different radial distances from the shaft and at different angular positions, allowing multiple accessories to share the same axial space while maintaining adequate mounting space for each. This spatial optimization reduces the overall gearbox volume.
Solution Approach 2:
The patent implements a nested arrangement where smaller accessories are positioned closer to the power transmission shaft while larger accessories are positioned at greater radial distances. This nesting strategy allows efficient use of the available space within the gearbox housing, maximizing the number of accessories that can be mounted without increasing the overall volume excessively.
3Device complexity
If the power transmission shaft is positioned to emerge from the front face, then the shaft layout is simplified, but the weight distribution of the assembly becomes unbalanced
Solution Approach 1:
The invention introduces asymmetric positioning of accessories relative to the power transmission shaft. Instead of distributing accessories symmetrically on both sides of the shaft, the patent positions certain accessories (such as the hydraulic pump and centrifugal compressor) at specific asymmetric locations. This asymmetric arrangement, combined with the front-face emergence of the power transmission shaft, maintains layout simplicity while achieving balanced weight distribution through strategic accessory placement.
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
Significantly reduces the total weight and size of the gearbox by utilizing only eight toothed wheels to drive nine accessories, achieving a balanced weight distribution and simplified assembly.
Implementation Method 1
a first gear train made up of three toothed wheels meshing with one another, and a second gear train made up of four toothed wheels meshing with one another
Implementation Method 2
a power transmission shaft that is coupled in rotation with the first and second gear trains by means of a toothed wheel pair
Data Source
AI summary
An assembly for driving accessories of a gas turbine is provided. The assembly includes: a gearbox having a front side face and a rear side face opposite the front face and having mounted therein a first gear train made up of three toothed wheels meshing with one another, and a second gear train made up of four toothed wheels meshing with one another; a power transmission shaft that is coupled in rotation with the first and second gear trains by a toothed wheel pair, and that emerges from the front side face of the gearbox; and nine distinct gas turbine accessories mounted against the side faces of the gearbox, and each including a respective drive shaft that is coupled in rotation with one of the toothed wheels of the two gear trains.