Hydrostatic Transmission Pressure Sensing for Shaft Shear Detection
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Solution Overview
Problem
Detecting mechanical transmission failures, particularly shaft shear events, in aircraft power plants is challenging due to complex system dynamics, and quickly identifying such failures while avoiding false alarms is difficult.
Innovation Solution
A hydrostatic transmission system using hydraulic fluid to transmit torque between shafts, equipped with a failure detector that senses pressure changes to detect mechanical failures, including shaft shear, by using pressure sensors and a computer to initiate mitigating actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical sensors are used to detect shaft shear, then the detection speed is fast, but false alarms increase due to complex system dynamics
Solution Approach 1:
The patent replaces traditional mechanical sensors with a hydrostatic transmission system that uses hydraulic fluid pressure to detect shaft shear events. The mechanical connection is substituted with a hydraulic coupling, where the pump and motor are connected via hydraulic fluid rather than direct mechanical linkage. This substitution eliminates false alarms caused by mechanical vibrations while maintaining fast detection response.
Solution Approach 2:
The patent introduces hydraulic fluid as an intermediary between the driving shaft and driven shaft. The hydraulic fluid transmits torque while isolating the detection system from direct mechanical vibrations. Pressure sensors monitor the hydraulic fluid pressure to detect shaft shear events, acting as an intermediary detection mechanism that filters out false alarm sources.
2Reliability
If pressure sensors are used to detect shaft shear, then false alarms are reduced, but detection speed may be slowed
Solution Approach 1:
The patent pre-charges the hydraulic system with pressurized fluid before operation. The hydraulic pump continuously maintains pressure in the hydraulic lines and motor, so that when a shaft shear event occurs, the pressure change is immediately transmitted to the sensors without delay for pressure build-up. This preliminary pressurization ensures both fast detection and reduced false alarms.
3Power
If direct mechanical connection is used between shafts, then torque transmission is efficient, but shaft shear detection is difficult
Solution Approach 1:
The patent uses a hydrostatic transmission system where a hydraulic pump driven by the first shaft pressurizes hydraulic fluid that drives a hydraulic motor connected to the second shaft. This hydraulic coupling transmits torque with high efficiency while allowing independent monitoring of the hydraulic fluid pressure to detect shaft shear events. The hydraulic system provides both efficient power transmission and inherent detection capability.
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
Facilitates early and accurate detection of mechanical transmission failures, reducing the likelihood of false alarms and enabling rapid mitigation actions.
Implementation Method 1
transmitting torque between a first shaft and a second shaft via a hydrostatic transmission operating with a hydraulic fluid at an expected pressure
Implementation Method 2
detecting the mechanical transmission failure by detecting a pressure change in the hydraulic fluid from the expected pressure
Data Source
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AI summary
Methods and systems for detecting a torque transmission failure in an aircraft power plant (36A; 36B) are provided. The system (10) comprises a hydrostatic transmission (12) for transmitting torque (T1, T2) between a first shaft (14) and a second shaft (16) using hydraulic fluid (18), a failure detector (20) including a sensor (22) configured to detect a pressure change in the hydraulic fluid (18). The failure detector (20) is configured to generate an output (26) indicative of the torque transmission failure in response to the pressure change having crossed a threshold (34).