문서 다운로드 () / 20
이메일 전송
다운로드
다운로드 한도를 초과했습니다.
Aerospace innovation continues to reach new heights. With next-generation airframes and more electric aircraft entering the fold, the industry is set to see increased changes across operational equipment and components. At Eaton, a major area of focus: actuation capabilities and performance.
One of the key trends influencing this area is the shift away from traditional hydraulic systems to advanced electromechanical actuators (EMAs). The accuracy and efficiency of EMAs have greatly improved over recent years, and they’re capable of handling the high forces that were once reserved for hydraulic actuators.
Still, many questions remain surrounding the timeline and viability of electric options. To help shed light, we’re answering the industry’s top questions about actuation trends and advancements.
While hydraulic and pneumatic actuation systems have been the market leader for decades, EMAs have become a viable, cost-effective alternative for aircraft. With that said, replacing hydraulic actuators with EMAs isn’t a simple drag-and-drop. The different operational capabilities and failure modes must be accounted for in safety assessments and trade studies.
Commercial and military aircraft OEMs are learning how to take advantage of the differences to achieve a lighter, more robust system design. In fact, A350 and B787 utilize EMAs for aircraft spoilers. EMAs also replaced hydraulics for thrust reverser systems on the A380, A350 and C919.
At Eaton, we’ve contributed to recent advancements with the development and production of an EMA system for the flaps on the EMBRAER Phenom 100. We’re excited to expand upon these developments with our customers.
No, an EMA isn’t less weight than a hydraulic actuator, at least not on a component-level assessment. However, we evaluate the entire system on aircraft to identify total weight reductions and savings.
When transitioning from hydraulic to EMA systems, we remove hydraulic lines that support the hydraulic equipment and its associated structure where possible, reducing overall weight.
Yes, in fact, the hybrid approach occurred more recently on A350 and B787 aircraft. Some systems are electric (brakes and spoilers) and others are hydraulic (ailerons). Also, various aircraft have implemented hybrid systems such as electric-hydraulic actuators and electric backup hydraulic actuators.
Hybrid systems often remove common failure modes if they are implemented correctly. When you combine the failure mode improvement with the advantages in fail-safety of the two systems, you positively impact aircraft system safety and reliability.
Additionally, the use of EMAs provides more data on the performance of the system, allowing for increased opportunities to use Prognostic/Predictive Health Monitoring (PHM). With this critical data available, you can make real-time decisions and schedule maintenance when needed.
The UAM market, especially when it comes to electric vertical take-off and landing (eVTOL), will drive continued innovation on actuation envelope and cost. The market segment requires smaller, higher-power actuation systems to be installed in the aircraft, even more so than the commercial market.
If eVTOL platforms hit suppliers’ projected volumes, the existing aerospace supply chain will need to keep pace with demand. A highly vertically integrated supply chain needs to be developed to produce actuation systems at greater volumes.
At Eaton, we developed the eActuation flap system for the Phenom 100 aircraft. It removes mechanical linkages between flap panels and maintains symmetry with electronic controls. The innovative system established a baseline for the intelligence and monitoring of the eActuators.
Building onto this development, we also provide monitors for future systems, which vastly augment the data communicated to the aircraft and increase the control performance of the entire system. The existing sensors and information can also be used to develop predictive health monitoring to increase the intelligence for maintenance activities.
The challenges of smart actuator implementation don’t have anything to do with the actuators themselves. They’re related to the complex electronics and software that control the actuators. As the criticality of the systems increases, so do the layers of redundancy and dissimilarity required to maintain their safety. Our engineering team is working hard to expand actuation technology as well as the controls and monitoring of the EMAs.
Historically, EMAs have been used in intermittent duty applications, running for only a few minutes during an aircraft’s flight. These low-duty cycle EMAs don’t need maintenance during their lifetime because of the minimal wear-inducing operations.
However, as EMAs generate less heat and become more efficient, they’re more suitable for continuous-duty applications which will increase the wear on the system. Hence, OEMs expect a different maintenance model for their operators/customers. There’s an intent to switch to a predictive schedule, which will include planned maintenance based on the condition of the components. Inevitably, there will be requirements for future aircraft components to have PHM in place so operators can plan for maintenance and increase dispatch reliability.
Our team continues to develop the PHM technology to support these requirements and needs for future aircraft.
With greater distribution opportunities, improved functionality, enhanced performance intelligence and reduced environmental impact, it’s clear that EMAs deliver critical benefits to the industry. But a few limitations remain, including:
Jamming: The increased number of mechanical components within an EMA (i.e. ball screws, gear trains, bearings, etc.) means there’s an increased probability of jamming issues. Jams can occur with those moving components versus the piston/cylinder design of a hydraulic actuator. As the power density of motors increases, there will be opportunities to remove more of those components from the load path.
Power density: A continued challenge related to EMAs is their lower power density. You can see this issue when comparing the weight and envelope of a similar-sized power hydraulic motor and an electric motor.
Failure mode: Finally, we’re asking actuation systems’ electronics, software and firmware to do more. Improvements in these areas will expand the certifications of these complex systems. With simple wires and switches, the failure modes are more limited. But if we used microprocessors to send control signals, the possibilities would expand exponentially.
Another key area of opportunity is the advancement of materials for actuator motors and electronics, which would deliver new temperature capabilities, extended life performance and improved reliability. Our engineers are working to resolve these limitations so we can drive expanded usage of EMA systems across the industry.
