Patent ID: 8353688

Claim:
A volumetric pump comprising: at least one piston inside a cylindrical housing having a longitudinal axis; a driving mechanism to cause a relative to-and-fro linear movement between the cylindrical housing and the piston along the direction of the axis in order to produce a stroke of the volumetric pump; and a bi-directional valve oscillatory rotatable about the axis which alternately connects at least one inlet port and at least one outlet port to at least one pump chamber located inside the housing; the driving mechanism having an eccentrically rotatable shaft which cooperates with the bi-directional valve to oscillate the valve about the axis, the shaft further pivotally cooperating with a connecting-piece that drives one of the piston and housing to provide relative to-and-fro linear movement therebetween in timed relation to the movement of the bi-directional valve so that at least one of the inlet and outlet ports in the bi-directional valve are closed when there is substantially no relative movement between the piston and the housing, wherein the at least one piston comprises a first fixed piston inside a first hollow cylindrical part and a second fixed piston positioned opposite to the first piston inside a second hollow cylindrical part, both cylindrical parts being assembled end-to-end facing each other to form the housing, the valve being mounted midway inside the housing, said valve being angularly movable such that it connects the inlet port alternately to a first and second chamber into which a fluid can be sucked through a first channel during a pump instroke and further connects the outlet port alternately to said first and second chamber where the fluid can be expelled through a second channel during a pump outstroke, said pump instroke and outstroke being produced by the linear sliding movement of the housing along the pistons.