GB1038017A - Improvements in or relating to piston pumps - Google Patents

Abstract

1,038,017. Reciprocating pumps. MUNCHNER MOTORZUBEHOR G.m.b.H. May 13, 1964 [May 28, 1963; March 16, 1964], No. 19842/64. Heading F1A. A pump comprises a plurality of pump bodies 5 arranged radially in reecesses 1a in a pump housing 1, tappets 8 reciprocated by a cam 2a, pump pistons 11 and suction and delivery ducts 5s and 5d which communicate with the pumping chambers 22 via suction and delivery valves 6a and 6b, respectively. The sub-atmospheric pressure of liquid drawn into the pumping chamber 22 by the spring biased piston 11 is controlled by an adjustable throttle 18. Chamber 21 between the tappet 8 and the piston 11 is in communication with chamber 1s surrounding the drive shaft 2 which is connected via a nipple Is<SP>11</SP> and a valve 1sd with a reservoir 19 in order that a constant pressure exists in the chamber. In operation, the piston 11 is moved outwardly by the tappet 8, the portion 8a striking a plate 11b of synthetic plastics material, e.g. polyamide, in the piston, and inwardly by piston biasing spring 14. The downward force of the spring 14 on the piston 11 is opposed by the net upward force created by the constant pressure in the chamber 21 and the sub-atmospheric pressure in pumping chamber 22. By adjustment of the throttle 18 and thus the subatmospheric pressure in chamber 22 the position in the piston stroke at which the forces are balanced and therefore the stroke of the piston 11 may be varied. In further embodiments Figs. 4 and 5 (not shown), the throttle 18 is mounted in a flange bolted to the housing 1 and comprises a manually operable rotary valve 18 and a slide valve 30 operated automatically by the pump delivery pressure, respectively.