Contactless Torque Sensor System by Liebherr-Aerospace: Now Available for Use in Serial Application
In state-of-the-art aircraft high lift systems, the power necessary to actuate the corresponding high lift devices is transmitted by mechanical shaft systems over distances of more than 60 meters.
The possibility of measuring the actual torque at any position of the complex mechanical transmission system brings essential possibilities and benefits:
- Precise control and limitation of the torque which is generated by the power drive units
- Detection and avoidance of overload conditions
- Detection of additional failures and damages, e.g. mechanical jams or fractures
Applying these solutions allows the design of much lighter mechanical components. In addition, new functionalities like “skew detection”, “health monitoring” and “failure isolation” can easily be realized. Through higher levels of integration and higher accuracy of load limitation functions, significant weight reductions of the system and even the aircraft wing structure are achievable.
Electronics printed circuit board
Magnetized transmission shaft with sensor coils
Housed electronics
High lift system testrig with contactless torque sensor system
Therefore, Liebherr has developed a sensor technology, which allows to measure contact-free the load torque of rotating metal shafts:
- A magnetic signature is applied directly on the corresponding transmission shaft (no additional components on the shaft necessary).
- The magnetic signature changes proportionally to the load torque of the shaft.
- The change of the magnetic signature is contactlessly captured by dedicated sensor elements (about 1 mm distance to the shaft) and evaluated by a simple electronic circuit.
Since 2016, the torque sensor technology is applied in the Liebherr high lift system flight test instrumentation equipment for a regional aircraft program. Up to now, it has successfully passed more than 2,500 flight hours.
During the last 24 months, the Liebherr technology integrated in dedicated high lift system equipment such as geared rotary actuator and power control unit, passed successfully all aerospace relevant performance and environmental tests as well as additional robustness and ageing test campaigns.
The contactless torque sensor measurement system is now available for use in future serial products by Liebherr-Aerospace.
