Planetary Gear System Pin Positioning for Gas Turbine Load Management
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Solution Overview
Problem
Planetary gear systems in gas turbine engines face significant mechanical loads, leading to displacements and requiring robust designs that efficiently distribute forces across multiple rows of gears.
Innovation Solution
A planetary gear system with two parallel rows of gears, where pins are positioned using extension elements with varying inclination angles and section moduli to create a stiff and lightweight support structure, allowing for efficient force distribution and minimizing tangential displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a robust support structure is used to withstand high mechanical loads, then the strength and reliability are improved, but the weight increases
Solution Approach 1:
The support structure employs varying section moduli in different regions: extension elements with higher section moduli are positioned in the aft row where mechanical loads are greater, while extension elements with lower section moduli are positioned in the front row where loads are lower. This localized optimization provides structural strength where needed while minimizing weight in less critical areas.
Solution Approach 2:
The patent utilizes different inclination angles for extension elements in different rows (smaller angles in the front row, larger angles in the aft row) and varies the section moduli to optimize the balance between mechanical robustness and weight. These parameter changes allow the structure to adapt to varying load conditions across different positions.
2Manufacturing precision
If pins are positioned further from the base structure to accommodate aft planetary gears, then the gear positioning is improved, but the tangential displacement increases under load
Solution Approach 1:
The support structure is designed with different geometric properties for different pin positions: extension elements supporting aft row pins (positioned further from the base structure) have larger section moduli and larger inclination angles, providing enhanced stiffness to counteract the increased lever arm and reduce tangential displacement. Front row pins have smaller section moduli and smaller inclination angles, optimizing their configuration for their specific position and load conditions.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The invention related to a planetary gear system (100) for a gas turbine engine (10), in particular an aircraft turbo engine with a plurality of planetary gears (31) coupled to a carrier device (35), with front planetary gears (31) mounted on pins (36A) in a front row (A) and aft planetary gears (31) mounted on pins (36B) in an aft row (B), the two rows (A, B) being parallel to each other in the axial direction of the planetary gear system (100), wherein the carrier device (35) comprises a ring-like base structure (37) around a rotational axis of the carrier device (35), the pins (36A, 36B) are coupled to of the carrier device (35) through extension elements (41 A, 41 B) for the positioning of the pins (36A, 36B) relative to the base structure (37), the second extension elements (41 B) axially extending the respective pins (36B) further away from the base structure (37) than the pins (36A) positioned by the first extension elements (41A), so that the aft planetary gears (31) are positioned in the aft row (B) axially further away from the base structure (37) than the front planetary gears (31) in the front row (A). The invention also relates to a gas turbine with a planetary gear system (100).