Development of a large load space-used paraffin actuator

Paraffin actuators have attracted a great deal of attention in the field of aerospace non-pyrotechnic actuators. The current aerospace paraffin actuator usually employs an elastic squeeze boot to push the actuator rod to move, which causes the disadvantages of large friction force and small force output. Motivated by these issues, a piston-type paraffin actuator has been developed in this paper. The actuator effectively enlarges the area that the liquid paraffin can apply pressure on, which greatly enhances the output driving force. The reset function and sealing performance have also been ensured by introducing a double-sealing design and a reset spring. In order to verify the proposed paraffin actuator, a prototype was fabricated. Validation experiments including friction force test, functional test, and life test have been performed. The results show that the reset spring with a designed force range of 85-165 N can successfully overcome the system friction force and push the piston to move, so as to ensure the auto-reset function. Under a rated power of 40 W (rated voltage 12 V), the output displacement of the actuator is 6.9 mm, the response time is 20 min, and the output force is more than or equal to 300 N. Life test shows that the actuator can function 100 times or more, and the output displacement is very stable (around 7 mm). Excellent sealing performance of the actuator has also been proven, since no paraffin leakage has been observed even after 100 times of actuation.