Patent ID: 7867198

Claim:
A medical liquid infusion apparatus provided with a driving portion and configured to infuse a medical liquid inside a medical liquid container into a patient by applying a pressure to the medical liquid container using a driving force of the driving portion, wherein: the driving portion includes a compressed gas cylinder filled with a compressed gas alone, and the driving force is generated by a pressure inside the compressed gas cylinder, the compressed gas cylinder including an on-off valve configured to close the compressed gas cylinder using a pressure of the compressed gas, when no external force is conferred thereto, wherein the driving portion further includes: a main body portion allowed to communicate with an interior of the compressed gas cylinder by opening the on-off valve; a diaphragm valve that defines a compression chamber capable of sealing the compressed gas flown from the compressed gas cylinder in a space between the main body portion and the medical liquid container; a pushing member that pushes the diaphragm valve toward the compression chamber from an outside open to atmosphere; and a link member that allows the on-off valve and the diaphragm valve to operate in synchronization with each other in such a manner that a first resultant force obtained by adding a force to close the on-off valve and a force to expand the diaphragm valve outward using the pressure inside the compression chamber is balanced out with a second resultant force to push the diaphragm valve toward the compression chamber using an atmospheric pressure and a pushing force of the pushing member, and wherein the pressure inside the compression chamber is used as the driving force.