Generator Input Shaft Assembly for Misalignment-Tolerant Disconnects
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Solution Overview
Problem
Existing disconnect devices for aircraft engines face reliability issues due to misalignment and lack of lubrication, leading to accelerated wear and reduced service life, which can hinder successful disconnection of generators from the engine's turbine.
Innovation Solution
A generator input shaft assembly that can float axially and rotate with a non-parallel axis to compensate for misalignment, combined with a fluid circuit for lubrication, ensuring reliable and durable operation even under high-speed conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the generator input shaft is fixed axially and rotates with a parallel axis, then the structure is simple and manufacturing is easy, but misalignment causes accelerated wear and reduced reliability
Solution Approach 1:
The generator input shaft is designed with dynamic freedom to float axially and rotate with non-parallel axes, allowing it to adapt to misalignment conditions. This dynamic capability enables the shaft to compensate for installation and operational misalignment, reducing wear on the drive transfer means and improving disconnect device reliability without requiring complex alignment mechanisms
Solution Approach 2:
The invention changes the operational parameters of the generator input shaft by allowing axial movement and non-parallel rotation. This parameter change enables the shaft to accommodate misalignment variations, reducing stress and wear on connected components while maintaining a relatively simple overall structure
2Duration of action of stationary object
If the drive transfer means operates without lubrication, then the structure is simple and maintenance is reduced, but wear accelerates and service life decreases
Solution Approach 1:
The drive transfer means is designed to be self-lubricating through material selection and surface treatment. The contacting surfaces incorporate lubrication properties either through self-lubricating materials or surface treatments that provide continuous lubrication, extending service life without requiring external lubrication systems or maintenance interventions
Solution Approach 2:
The drive transfer means utilizes composite materials or surface treatments that combine structural integrity with lubrication properties. This allows the component to provide its own lubrication, reducing wear and extending service life without adding the complexity of external lubrication delivery systems
3Force
If mechanical power is extracted from the rotating drive shaft to operate the disconnect mechanism, then very high actuating forces and rapid disconnection are achieved, but very accurate tolerances are required and the assembly process becomes complex
Solution Approach 1:
A spring-loaded actuating mechanism serves as an intermediary between the control system and the disconnect mechanism. The spring stores energy and provides the necessary actuating force, while the actuator simply needs to overcome spring pressure rather than generate high forces directly. This intermediary approach reduces the required manufacturing precision and simplifies the assembly process while still achieving reliable disconnection
4Reliability
If a large actuator and mechanical advantage mechanism are used, then the assembly process becomes more robust and reliability improves, but the axial force produced is limited and may not be sufficient for disconnection
Solution Approach 1:
The disconnect mechanism utilizes the dynamic rotational energy of the drive shaft to amplify the actuating force. By timing the actuation with the rotational cycle and using the rotational momentum, the system can generate high axial forces without requiring large static actuators or complex mechanical advantage mechanisms, maintaining both reliability and sufficient force output
Data Source
AI summary
The present invention relates to a generator input shaft assembly comprising a generator input shaft (160) arranged to receive a drive input to the generator, and a disconnect input shaft (120) arranged to deliver a drive input from the generator input shaft to a disconnectable drive transfer means (116). The disconnectable drive transfer means is configured to transfer rotational drive from the generator input shaft assembly to a rotor (110) of the generator. The generator input shaft assembly is configured such that the generator input shaft can: float axially relative to the disconnect input shaft and/or drive the disconnect input shaft with an axis of rotation of the generator input shaft non-parallel to an axis of rotation of the disconnect input shaft, so as to compensate for a misaligned input to the generator input shaft. Other aspects of the invention relate to a generator and a system comprising the generator input shaft assembly.