Patent ID: 6935846

Claim:
A dosing pump, comprising: a separation means; a chamber having an axis, the chamber being partitioned by the separation means into two partial chambers; an inlet communicated via an inlet valve with one of the partial chambers for the flow of dose liquid into the chamber; and an outlet communicated via an outlet valve for flow of dose liquid out of the chamber, the dose liquid overall path of the separation means being alternatingly movable in a feed direction along an axis in a manner which effects the discharge of dose liquid from the chamber outwardly through the outlet valve and in a reverse direction axially opposite to that of the feed direction in a manner which effects re-positioning of the separation means for the subsequent movement of the separation means in the feed direction, the separation means having a one-way separation valve permitting flow of dose liquid therethrough during movement of the separation means in the reverse direction and not permitting flow therethrough during movement of the separation means in the feed direction, each of the partial chamber having outer walls with the outer wall of each partial chamber being generally co-axially aligned with the outer wall of the other partial chamber and the length of each outer wall being variable in the axial direction to at least one of an axially compressed length and an axially extended length, and the separation means being sealingly connected with the outer walls of the partial chambers and being operatively connected with a drive device for driving movement of the separation means, wherein the outer walls of the partical chambers are comprised of substantially cylindrical tube parts, wherein the separation means is formed of hard material and comprises an outer threaded winding, an inner threaded winding, a transmission part, and means for cyclic reversal of the rotation direction of the transmission part, the outer threaded winding being co-axial to the feed direction and in force transmission engagement with the inner threaded winding via the transmission part which is rotatably driven by the drive device, and the means for cyclic reversal of the rotation direction of the transmission part cyclically reversing the rotation direction of the transmission part to effect alternating movement of the separation means.