Fluid ejection device with reinforced seal

A device for ejecting a fluid comprising:

• a reservoir of a substantially cylindrical shape having a first end and a second end opposite the first end, the reservoir having a shoulder on an inner surface of the reservoir near the second end of the reservoir;
• a separating element dividing the reservoir into first and second chambers, the separating element including an expandable locking element in contact with the inner surface of the reservoir, the shoulder being configured to permit the expandable locking element to expand when the separating element has moved to a position where the expandable locking element has moved past the shoulder in a direction toward the second end of the reservoir, wherein the shoulder and the expandable locking element have mutually engaging shapes that lock the expandable locking element against movement in a direction toward the first end of the reservoir when the expandable locking element engages the shoulder after the separating element has moved to a position where the expandable locking element has moved past the shoulder in a direction toward the second end of the reservoir;
• a seal provided between the separating element and side walls of the reservoir, the separating element configured to slide in the reservoir along a longitudinal axis of the reservoir and in contact with the inner surface of the reservoir from the first end to the shoulder, so as to change relative volume of the chambers, the first chamber being filled with a fluid and including an orifice closed by a cap so that the fluid may be ejected from the reservoir through the orifice under effect of translational movement of the separating element from the first end of the reservoir to the second end of the reservoir and an opening of the cap, wherein the shoulder is configured to increase the dimensions of the reservoir such that the seal does not contact the inner surface of the reservoir in a direction from the shoulder toward the second end of the reservoir, over a length of the reservoir sufficient that the second chamber can be depressurized when the separating element has moved to a position where the seal is located between the shoulder and the second end;
• a fluid distribution circuit connected to said orifice;
• a pyrotechnic gas generator in communication with the second chamber;
• means for putting gases generated by a pyrotechnic reaction at the pyrotechnic gas generator in communication with the fluid distribution circuit upon ending ejection of the fluid;
• and
• means for modifying pressure in the second chamber, so as to cause a translational movement of the separating element, wherein the second chamber comprises a thimble configured to sealably separate an inside of the second chamber from the side walls of the reservoir, the thimble being broken beyond a defined longitudinal position of the separating element.