Thermic control element

In a thermic control element of the type including a plate-like wall part, a membrane member peripherally coupled to said wall part, a locking element supported on one side of the membrane for stroke movement between an open and closed end position and a counter plate supported on the other side of said membrane and facing the wall plate, wherein the locking element, the membrane member and the counter plate are rigidly coupled together in their central area, wherein the wall part has a cup-shaped curvature with a support face for a peripheral zone of the counter plate and wherein a receiving chamber is defined between said wall part and said membrane member in which an expansion medium is received, the improvement comprising:

• said locking element in its open end position and said wall part being provided with corresponding cooperating, centrally disposed stroke engagement faces which are positioned such that, in the closed end position of said locking element, the axial distance between said stroke engagement faces of said locking element and said wall part is less than the axial distance between the support faces of the wall part and said peripheral zone of said counter plate so that, under normal operating conditions, only the axial distance between said stroke engagement faces of said locking element and said wall part will be bridged by means of said centrally disposed stroke engagement face of said locking element engaging said stroke engagement face of said wall part in said closed end position thereof and, so that under extreme loads and upon deformation of said wall part, the axial distance between said support face of said wall part and said peripheral zone of said counter plate will also and subsequently be bridged with said peripheral zone of said counter plate engaging said support face of said wall part so that an additional support is provided.