US Patent 9821136 Opening and closing device and respiratory assistance device

A respiratory assistance device 10 includes: a mask 13 having an expiratory hole 13a; an expiratory valve 15 provided in the mask 13, for opening and closing the expiratory hole 13a; and a control unit 17 for performing overall control on the entire device. The mask 13 and the expiratory valve 15 together form an opening and closing device. The expiratory valve 15 is deformable by deformation of a piezo element 15a. The expiratory valve 15 is disposed on an inner surface 13f so that a deformation direction thereof, i.e., a thickness direction thereof, extends along the inner surface 13f of the mask 13 and a side surface 15m slides along the inner surface 13f by the deformation thereof.