Patent ID: 7922694

Claim:
A drive device for a piston in a container containing a liquid product, the container having limiting lateral walls that extend in a longitudinal direction toward an outlet for the liquid product, the drive device comprising: a first segment having an actively variable shape, the first segment having a first shape in which the first segment is clamped between the lateral walls of the container and having a second shape in which the first segment is released from the lateral walls, a first paraffin actuator configured to actively vary the first segment between its first and second shapes, a second segment having an actively variable shape, the second segment having a first shape in which the second segment is clamped between the lateral walls of the container and having a second shape in which the second segment is released from the lateral walls, the first segment being positioned between the second segment and the outlet, a second paraffin actuator configured to actively vary the second segment between its first and second shapes, and a connecting segment connecting the first segment to the second segment, the connecting segment having an actively variable connecting length, wherein the container has a circular cross section, wherein the first segment comprises a first clamping ring that is clamped in its first shape to an inner wall of the container and is released from the inner wall in its second shape, wherein the second segment comprises a second clamping ring that is clamped in its first shape to the inner wall of the container and is released from the inner wall in its second shape, wherein the first clamping ring defines a first ring diameter that can be varied by activating the first paraffin actuator, wherein the second clamping ring defines a second ring diameter that can be varied by activating the second paraffin actuator, wherein the first clamping ring comprises a first open ring with two tongues projecting into the first open ring, and wherein the first paraffin actuator is positioned between the two tongues of the first open ring and has a thickness that is actively variable.