Gear Overtorque Protection via Breakable Disc and Guide Module
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Solution Overview
Problem
In gear trains used in turbomachines, if a driven shaft is seized, the pinion integral with the shaft can no longer rotate, leading to a potential blockage of the entire kinematic chain, resulting in loss of torque and inefficiency, and requiring costly and time-consuming replacement of parts.
Innovation Solution
A breakable element, such as a disc with radial arms, is removably mounted between the pinion and shaft, activating a guidance module with rollers to constrain axial and transverse movements of the disengaged pinion, allowing it to rotate while maintaining efficiency and enabling quick replacement of parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pinion is integrally mounted on a shaft using a key, then the connection is strong and reliable, but the entire pinion and shaft must be replaced when the key fails under overtorque
Solution Approach 1:
The connection between pinion and shaft is segmented into multiple replaceable elements: the key, the disc, and the radial arms. When overtorque occurs, only the radial arms break while the key and disc remain intact, allowing rapid replacement of just the broken arms rather than the entire pinion-shaft assembly.
Solution Approach 2:
The radial arms are designed as disposable sacrificial elements that break under overtorque to protect more expensive components. These arms can be quickly replaced without replacing the entire pinion or shaft, reducing repair time and cost.
2Reliability
If a shaft is seized, then the pinion cannot rotate and the kinematic chain is blocked, but providing fuse means causes the pinion to become off-axis and lose torque transmission
Solution Approach 1:
The disc with radial arms acts as an intermediary between the pinion and shaft. It provides a controlled failure mode where the radial arms break instead of allowing uncontrolled off-axis movement, maintaining better alignment and torque transmission while still protecting against seized shafts.
Solution Approach 2:
The radial arms are designed to break at a predetermined torque threshold, cushioning the shock of overtorque before it can cause damage to the pinion or shaft. This beforehand protection allows the system to handle seized conditions without complete failure of torque transmission.
3Ease of manufacture
If the pinion is secured to the shaft with a key in a rectangular notch, then the mounting is simple and robust, but the breakable element cannot be quickly replaced
Solution Approach 1:
The breakable element is segmented into the disc with radial arms as a separate, pre-assembled unit that can be quickly removed and replaced. The radial arms are the only parts that need replacement, not the entire disc or pinion, significantly reducing replacement time.
Solution Approach 2:
The disc with radial arms is pre-assembled as a complete unit before installation. This preliminary assembly allows for rapid replacement of just the broken radial arms without disassembling the entire pinion-shaft connection, saving valuable maintenance time.
Data Source
Figure 1~2
Figure 3
AI summary
The gear has a pinion (20) integrated to a shaft (201) rotary mounted in a support through a breakable element. The breakable element is arranged for disintegrating the pinion of the shaft in an event of over-torque between the pinion and the shaft. A guide module (50) is arranged with respect to the pinion for maintaining the pinion in rotation on the support during disintegration of the pinion of the shaft. The breakable element is formed of a disk (40) that is incorporated between the pinion and the shaft, where the disk comprises a breakable radial arm.