Valve, in particular a control or shut-off valve for liquid or gaseous media

Valve, in particular a control or shut-off valve for liquid or gaseous media with a valve housing (12) having at least one through-bore (14) connecting an inlet opening (21) with an outlet opening (16), with one (in the valve-closing body 12) arranged and the through-bore (14) surrounding the valve seat (17), which is closable by a valve closure member (31), which regulating space formed in a (the valve housing 12) between the inlet opening (21) and the outlet (16) (22) is arranged with a to the valve housing (12) connected drive (35) for controlling the opening and closing movement of the valve closure member (31) has at least one actuating element (39) of a shape memory alloy and the valve closure member (31) for opening or closing the through hole (14) and operated with a restoring element (33) having a closing or opening movement of the valve chliesgliedes (31) counteracts the actuating element (39) is formed from at least one wire element and is actuated by energization with a control device (44) and the actuating element (39) between an engagement point (34) of the valve closing member (31) and a point of application (37) on the valve housing (12) or attachable thereto housing section (19) acts, and the control element (39) in the media-flow regulating space (22) is arranged, characterized, - that the actuating element (39) in sections by a protective sleeve (45) is surrounded, - that the protective sleeve (45) is loosely fitted over the actuator (39) and between the protective sleeve (45) and the actuating element (39) a small annular gap is formed, and - that the length of the protective sleeve (45) corresponds to the length of the activated control element (39) when said valve closure member (31) in a maximum opening position or is shorter.