Pneumatically-Controlled Linear Actuator Using Pressure-Resistant, Thin-Walled Metal Bellows and its Application

The use of pneumatics has led to the development of a linear actuator that incorporates pressure-resistant metal bellows. This pressure-resistant bellows device is airtight and capable of considerable expansion. Conventional bellows devices are susceptible to bending stresses at the folds because high air pressure tends to crush the curvature of the bellows there. Therefore, their application only uses a 0.1 MPa difference in inner/outer pressure. The pressure-resistance of the bellows device is improved by the installation of viscoelastic rings in its folds, rings which reduce the bending stress caused by the high air pressure at the thin-walled inner folds. As a result, the pressure resistance is increased by 0.7 MPa. This paper uses a theoretical formulation and a finite element analysis approach in reporting the improvement in pressure resistance made by the installation of the viscoelastic rings. Furthermore, the actuator with pressure-resistant, thin-walled metal bellows is used to control the posture and damping force of a vehicle’s active suspension.