Disengageable Speed Reducer Ring for Jam-Triggered Uncoupling
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Solution Overview
Problem
Conventional speed reducers in aircraft turbomachines can jam due to blockages, leading to system rupture and increased drag, which affects maneuverability, and existing safety devices introduce flexible zones that harm the dynamic behavior of the low-pressure line.
Innovation Solution
A speed reducer design featuring an annular ring with offset half-crowns and a support plate that allows uncoupling of pinions from the half-rings when a disengagement action exceeds a certain amplitude, maintaining a rigid system without introducing flexible zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional safety devices are introduced into the low pressure line, then the function of mechanical fuse is achieved, but flexible zones are introduced which harm the dynamic behavior of the line
Solution Approach 1:
The annular crown is divided into two independent half-crowns offset along the rotation axis, each capable of uncoupling independently from the pinion. This segmentation allows the mechanical fuse function to be distributed across multiple rigid elements rather than requiring a single flexible zone, thereby maintaining the dynamic behavior of the low pressure line while achieving the safety function.
Solution Approach 2:
The half-crowns are designed to transition from a coupled state (engaged with the pinion) to an uncoupled state (disengaged from the pinion) when excessive torque is applied. This dynamic capability allows the system to respond to blockage conditions by uncoupling the half-crowns, providing the mechanical fuse function without requiring permanently flexible zones that would compromise the dynamic behavior of the line.
2Stability of the object's composition
If the system is made rigid to maintain dynamic behavior, then the dynamic behavior is preserved, but the ability to uncouple elements during blockage is reduced
Solution Approach 1:
The annular crown is segmented into two independent half-crowns that can uncouple independently. This segmentation maintains rigidity within each half-crown element (preserving dynamic behavior) while enabling uncoupling capability at the interface between the half-crowns and the pinion, thus resolving the contradiction between rigidity and adaptability.
Solution Approach 2:
The half-crowns are designed to automatically uncouple from the pinion when excessive torque is applied during a blockage condition, without requiring external intervention. The offset positioning and independent mounting allow the half-crowns to self-disengage, providing adaptability during blockage while maintaining rigid construction during normal operation.
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~4C
AI summary
The invention relates to a speed-reducing unit (10), particularly for transferring torque between a gas turbine and a fan in a turbine engine, comprising an annular ring (18), at least one gear (14) that is coupled to the ring (18), wherein the ring (18) comprises two annular half-rings (24) that are offset relative to each other along the main axis of the speed-reducing unit (10) and that are coupled with said at least one gear (14), and a plate (26) for supporting the two half-rings (24), in relation to which the two half-rings (24) are rotationally fixed about the main axis of the speed-reducing unit (10), each half-ring (24) comprising an internal helical tooth, characterised in that each half-ring (24) is connected to the support plate (26) so as to be able to be uncoupled from said at least one gear (14) when said at least one gear (14) exerts a disengaging action on each half-ring (24), with the amplitude of said action being greater than a determined amplitude value.