Planet Gearbox Layshaft Geometry for Grinding Wheel Clearance
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Solution Overview
Problem
Current planet gear designs for turbine engine power gearboxes do not account for the size of grinding wheels during manufacturing, leading to inefficiencies in weight, size, and efficiency, and there is a need to minimize the overall weight of the gearbox while maintaining high torque transfer efficiency.
Innovation Solution
The design incorporates a layshaft with a Lambda shape, featuring a Radial Stage Distance that ensures the grinding wheel can access the gear teeth without interference, allowing for a more compact and lighter gearbox assembly by optimizing the first and second stage planet gear dimensions and the grinding wheel diameter relationship.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional planet gear designs are used without considering grinding wheel size, then the gearbox can be manufactured with standard processes, but the gearbox weight and size are increased and manufacturing efficiency is reduced
Solution Approach 1:
The patent applies preliminary action by designing the layshaft with a Lambda shape and optimizing the radial stage distance before manufacturing begins. This pre-planned geometric configuration ensures that grinding wheels can access gear teeth during the manufacturing process, preventing interference issues from arising later and enabling both weight reduction and manufacturing efficiency
Solution Approach 2:
The patent utilizes dimensional optimization by specifically controlling the radial stage distance (a radial dimension) to accommodate grinding wheel diameter requirements. By optimizing this radial dimension, the design enables grinding wheel access without increasing axial length, thus reducing overall gearbox weight while maintaining manufacturability
2Ease of manufacture
If the radial stage distance is increased to accommodate grinding wheel diameter, then grinding access is improved, but the axial length of the gearbox increases
Solution Approach 1:
The patent applies local quality by optimizing the radial stage distance specifically in the radial dimension where grinding wheel access is needed, rather than uniformly increasing dimensions in all directions. This localized optimization allows grinding wheels to access gear teeth while keeping the axial length compact, resolving the contradiction between manufacturability and compactness
3Weight of moving object
If the gearbox size is reduced to decrease weight, then weight efficiency is improved, but grinding wheel access during manufacturing becomes difficult
Solution Approach 1:
The design incorporates preliminary action by pre-calculating and setting the radial stage distance to be greater than or equal to the grinding wheel diameter before manufacturing. This ensures that even in a compact, weight-reduced gearbox design, grinding wheels will have sufficient access to gear teeth during manufacturing, maintaining manufacturing precision while achieving weight reduction
Solution Approach 2:
The patent applies parameter changes by optimizing the radial stage distance parameter to satisfy both the compactness requirement (for weight reduction) and the grinding wheel access requirement (for manufacturing precision). By changing this critical geometric parameter, the design achieves both goals simultaneously
Data Source
AI summary
A gearbox assembly includes a plurality of planet gears. At least one planet gear of the plurality of planet gears includes a layshaft that supports a first stage planet gear and a second stage planet gear. The at least one planet gear is characterized by a Radial Stage Distance greater than or equal to 30 millimeters and less than or equal to 100 millimeters. The Radial Stage Distance is Rrm1−Rrt2. Rrm1 is a first stage rim inner radius of the first stage planet gear and Rrt2 is a second stage root radius of the second stage planet gear.