Helicopter Rotor Actuator With Segmented Harmonic Drives
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Solution Overview
Problem
Actuators for aviation applications, such as those used in helicopters, are susceptible to damage and malfunction, which can lead to critical failures in aircraft control systems, necessitating the development of a more reliable and redundant system.
Innovation Solution
An actuator design featuring an electromechanical drive assembly subdivided into independent sub-drives, connected by a transmission composed of strain wave gearings or harmonic gearings, which separates sub-drives spatially and incorporates power drive electronics and actuator control units for independent regulation, along with locking elements and braking mechanisms to maintain functionality in case of sub-drive failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive assembly is subdivided into independent sub-drives with spatial separation, then reliability is improved, but device complexity increases
Solution Approach 1:
The drive assembly is divided into multiple independent sub-drives (first sub-drive and second sub-drive) that are spatially separated by the transmission. Each sub-drive can operate independently, so that if one fails, the other can maintain control functions. This segmentation directly improves reliability by reducing the susceptibility to damage from single-point failures.
Solution Approach 2:
The transmission is positioned between the two sub-drives, creating a nested arrangement where the transmission serves as both a functional component and a spatial separator. This nesting allows the system to achieve spatial separation for reliability while maintaining a compact overall structure, thus managing device complexity.
2Reliability
If redundant sub-drives are implemented, then mean time between failures increases, but manufacturing cost increases
Solution Approach 1:
The system uses segmented sub-drives that can be manufactured as modular units. This modularity allows for standardized production processes while achieving redundancy, as each sub-drive module can be independently manufactured and tested before assembly into the complete actuator system.
Solution Approach 2:
The transmission component serves multiple functions: it transmits mechanical power from the sub-drives to the output drive, and simultaneously acts as a spatial separator between the redundant sub-drives. This multi-functionality reduces the number of separate components needed, thereby reducing manufacturing complexity and cost while maintaining the redundant architecture.
3Reliability
If spatial separation of sub-drives is implemented, then reliability is improved, but volume increases
Solution Approach 1:
The transmission is nested between the two sub-drives in a compact arrangement that minimizes the overall volume. The spatial separation required for reliability is achieved through efficient use of the transmission's position, creating a compact nested structure rather than a dispersed layout, thus limiting the increase in actuator volume.
Solution Approach 2:
The sub-drives are arranged in different spatial dimensions with the transmission positioned between them, utilizing three-dimensional space efficiently. This dimensional arrangement allows for spatial separation to improve reliability while maintaining a compact overall volume by optimizing the use of available space in multiple directions.
Data Source
AI summary
An actuator for aviation applications, in particular for adjusting rotor blades in a helicopter, may include an electromechanical drive assembly connected to an output drive via a downstream transmission, where the drive assembly is divided into sub-drives that can be operated independently, and where at least two sub-drives are spatially separated from one another in that the transmission is placed between these sub-drives. The transmission may include at least two harmonic gearings coupled to one another by at least one first coupling element, where a first harmonic gearing is located inside a non-rotating first housing, where a second harmonic gearing is located inside a rotating second housing, and where the second housing is connected to the output drive.