Use of an intumescent material and device having a material of this type

1. A door opener, comprising:

a housing with an inner wall;

a pivot latch;

a changeover switch;

an armature;

an intumescent material, having an expansion temperature, positioned on the inner wall of the housing proximate to the armature; and

a plurality of free spaces disposed between the inner wall and the pivot latch, the inner wall and the changeover switch, and the inner wall and the armature,

wherein the intumescent material volumetrically expands into the free space between the inner wall and the armature and permanently embeds the armature in a locking position when the expansion temperature has been reached.

2. A door opener according to claim 1 , wherein the armature is implemented as a pivot lever on a joint and is pre-tensioned using an armature spring in such a way that the armature is held in a locking position, and wherein the expanded intumescent material presses against the armature and holds the armature in the locking position independently of the action of the armature spring.

3. A door opener according to claim 2 , wherein the intumescent material is positioned so that the expansion pressure acts on the pivot lever of the armature.

4. A door opener according to claim 1 , further comprising additional intumescent material positioned on the inner wall proximate to the pivot latch and the changeover switch, wherein the additional intumescent material volumetrically expands into the free spaces between the inner wall and the pivot latch, and the inner wall and the changeover switch, and blocks the movement of the pivot latch and the changeover switch when the expansion temperature has been reached.

5. A door opener according to claim 1 , wherein the intumescent material is glued to the housing wall.

6. A door opener according to claim 1 , wherein the inner wall includes a recess and the intumescent material is positioned in the recess.