Patent ID: 7470402

Claim:
Automatic precision drawing-off device comprising at least first and second pumping units having a respective first and second working chambers whose volumes vary according to the axial position of two respective rod/piston units which slide in said working chambers, said rod/piston units being coupled to an actuation member driven by a common motor, said working chambers being connected to a circuit successively comprising a pipe opening into a rinsing liquid reserve, first and second successive electrovalves and a circuit portion connecting said second electrovalve to drawing-off means, said first working chamber being connected to said circuit in a region forming a link between said first electrovalve and said second electrovalve, said second working chamber being connected to said circuit portion by means of a connector, wherein said circuit portion comprises a third electrovalve directly connected between said connector and said drawing-off means, said electrovalves and said motor being controlled by control means configured to obtain at least a drawing cycle from an initial status where the drawing-off means is engaged in a receptacle, said first and second electrovalves are open and the third electrovalve is closed, the motor is stopped, and the rod/piston units are in an idle position, wherein said control means comprises means for controlling said drawing cycle to include: a first transitory step in which the rod/piston units are driven by said motor in a first direction to create a sucking of said rinsing liquid into the two working chambers while elements of said motor are in abutment against one another, a drawing-off phase obtained by closing said second electrovalve and by opening the third electrovalve, the two rod/piston units being moved in said first direction so that said first pumping unit sucks up the rinsing liquid contained in said reserve and the second pumping unit creates suction of the product contained in said receptacle into said drawing-off means, and a second transitory phase marked by the closure of said third electrovalve and the opening of the second electrovalve so that said drawing-off phase is ended whereas the motor continues to drive said rod/piston units in said first direction thus provoking a suction by the two chambers of the rinsing liquid derived from said reserve, the motor being stopped at the end of this second transitory phase.