Aircraft Accessory Drive Parasitic Torque Limiter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current aircraft accessory drive systems lack efficient mechanisms to decouple critical and less critical accessories during jams, potentially leading to failure and loss of essential functions.
Innovation Solution
An aircraft accessory drive system incorporating a parasitic drive system with a torque limiter, such as a shear neck, that decouples from the drive shaft and critical accessories in case of a jam, ensuring the critical accessories remain operational by breaking at a predetermined torque lower than the direct coupling failure point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a parasitic drive system is coupled to the drive shaft to drive less critical accessories, then the drive system can power multiple accessories, but a jam in the parasitic drive system can cause failure of the critical accessory
Solution Approach 1:
The drive system is segmented into a critical accessory drive path and a parasitic accessory drive path. The parasitic drive system includes a torque limiter that can decouple the parasitic path from the drive shaft, allowing the critical accessory to continue operating independently if the parasitic path jams
Solution Approach 2:
A torque limiter acts as an intermediary component between the drive shaft and the parasitic drive system. This intermediary mechanism allows normal power transmission to both critical and less critical accessories, but automatically decouples when excessive torque is detected, protecting the critical accessory from damage due to jams in the parasitic path
2Reliability
If a torque limiter is added to decouple the parasitic drive system, then the critical accessory is protected from jam-induced failure, but the device complexity increases
Solution Approach 1:
The torque limiter is designed as a sacrificial component that can fail in a controlled manner (e.g., shear pin breaking, friction disc slipping) to protect the critical accessory. This disposable or resettable mechanism provides reliable protection without requiring complex sensing or control systems
Solution Approach 2:
The torque limiter automatically detects and responds to jam conditions through self-contained mechanisms such as friction-based slip clutches, shear pins, or detent mechanisms. No external sensors, controllers, or complex monitoring systems are needed - the torque limiter self-regulates based on torque conditions
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
This solution ensures that critical accessories continue to function even if the parasitic drive system jams, prioritizing safety-critical components while allowing less critical accessories to be sacrificed, thereby maintaining essential operations.
Implementation Method 1
The torque limiter may be a shear neck in a parasitic drive shaft of the parasitic drive system
Implementation Method 2
The torque limiter may be, or may comprise one or more shear pin, friction, detent, hydraulic, magnetic, or electronic torque limiters
Data Source
AI summary
Disclosed is an aircraft accessory drive system comprising: a drive shaft configured to provide a drive input; a critical accessory directly coupled to the drive shaft so as to be directly driven by the drive shaft; a parasitic drive system configured to transmit drive input from the drive shaft to one or more less critical accessories, wherein the parasitic drive system comprises a torque limiter configured to decouple the parasitic drive system from the drive shaft and the critical accessory in response to a jam affecting the parasitic drive system or one or more of the less critical accessories. Also disclosed are a gas turbine engine comprising an aircraft accessory drive system, and an aircraft comprising an aircraft accessory drive system.