Device for monitoring closed condition of machine protection guard with retention device holding movable part of guard in closed or open position via retention element operated via shape memory element

摘要

The device (1) has a protection device, e.g. a safety switch, for monitoring the closed condition of the protection guard (2) having a first part (4) with an access opening (5) and a relatively movable part (6) for closure of the access opening, respectively provided with a switch element (7) and a switch operator (8), cooperating for providing an electrical signal indicating the closed or open position of the access opening. A retention device for holding the movable part in the open or closed position has a retention element, operated by a drive with at least one shape memory element exhibiting a reversible shape alteration in response to an electrical signal.