GB1283907A - Volumetric metering pump - Google Patents

Abstract

1283907 Semi-rotary pumps RHONEPOULENC S A 22 Oct 1970 [23 Oct 1969] 50285/70 Heading F1F An oscillatory-piston semi-rotary volumetric metering pump for accurately dosing very small quantities of liquid i. e. providing a regular delivery of pulsed liquid with very great precision for use in laboratory work such as chromatography, comprises two arcuate inter-connected pistons 3, 4 movable in a series of pulsed jerks in two separate correspondingly arcuate cylinders 5, 6 by a rockable arm 7 fast on the shaft 8 of a mechanical impulse generator such as a reversible "step-by-step" electric motor 1 rotating through a specific angle at each impulse supplied by an electronic device of known type (not shown), the arm 7 moving through a sector of a circle whose amplitude is limited by two abutments 19, 20 each provided with a limit micro-switch 10, 11 actuation of each of which, by striking engagement of the rocking arm 7, reverses the rotation of the step-by-step motor whereby the arm 7 is oscillated between the abutments to create the pumping action, a distributing slide valve 50 selectively and alternatively acting as a suction and delivery valve via ducts 12, 13 connected between the valve 50 and the two separate cylinders 5, 6, the slide valve 50 being controlled by a pair of opposed solenoids 29, 30 alternatively energised and de-energised by a control switch 69 which simultaneously reverses the electric motor drive in the interval of time between two consecutive pulses as the arm 7 alternatively strikes the abutment limit switches 10, 11 which operate the electrical control switching arrangement 69. The pump may alternatively be controlled by a motor driving a ratchet wheel device for generating and regulating mechanical impulses to the arm 7. A mechanical, electro-mechanical or electronic speed varying device may be provided for adjusting the time between successive pulses for readily adjusting a dose to a desired value and for covering a wide range of doses. The pump cylinders 5, 6 may, as shown, form parts of the same circle, or, the pump cylinder's partcircular axes may be parallel and coaxial to one another.