Image Number 3 for United States Patent #5423482.
An apparatus and a method of injecting a liquid are provided, especially for the intermittent, essentially drip-free injection of a liquid into a waste heat removal system in a spacecraft. The injection apparatus includes a housing having an inlet, an outlet, a discharge channel communicating with the outlet, and a receiving chamber controllably communicating with the discharge channel. A piston is movably arranged in the housing to define a boundary of the receiving chamber. A valve arrangement operates in response to the motion of the piston to respectively open or close the path of liquid communication between the receiving chamber and the discharge channel. This apparatus carries out the method, whereby when delivery of injection liquid is to be stopped any liquid remaining in the discharge channel is sucked out into the receiving chamber. Then, when delivery of injection liquid is to be resumed, the retained liquid is moved from the receiving chamber into the discharge channel.