Adaptive Resetting of Shape Memory Alloy Actuators for Automotive Interior Applications

摘要

In the last decades automotive systems have been refined from simple mechanisms to intelligent components consisting of mechanics, actuator-sensor devices with integrated electronics and software. Common automotive actuators are electrodynamic drives and solenoid systems which are used in a wide field of applications as shown in figure 1 (left). Interior applications, like comfort systems or safety systems, have to fulfill different requirements. Apart from that, general technical specifications for application groups can be summed up regarding element weight and functionality at specified ambient temperatures. This publication concentrates on these specific requirements with relation to shape memory technology. These smart elements can be used in today's applications as lightweight actuators therefore as substitution for electromagnetic drives only with limitations regarding the ambient temperatures (T_a). Due to their characteristics, common SMA actuators retransform at lower temperatures than T_a ≥ +85°C. In order to increase the transformation temperatures of SMA wires, the SMA actuators' prestress level has to be raised. As presented in [1], the cyclic fatigue of SMA actuators decreases with higher prestress.