ES345457A1 - Pump - Google Patents

Abstract

A rotary pump comprising pumping means, including a cam ring having a radially inwardly facing surface, a rotor secured tc a shaft and disposed within the cam ring and pumping elements disposed in respective circumferentially spaced slots around the rotor, engageable with the inner surface of the cam ring and on rotation of the rotor reciprocable in their slots to vary the volume of pockets between adjacent elements, the cam ring and the rotor, an end member at each axial side of the pumping means fixed relative to the cam ring provided with inlet port means comprising an inner port radially inwards of a pumping element passing the port and an outer port disposed radially outwards of the inner port and inlet passage means leading to the inlet port means constructed such that the pressure of fluid entering the inner ports is greater than that entering the outer ports. As shown, a rotor 14, Fig. 1, secured to a shaft 13 is formed with a plurality of circumferentially spaced slots 21, Fig. 6, in each of which is mounted a roller 16 which engages the inner surface 20 of a cam ring 15 and reciprocates in its slot to pump liquid from a reservoir 30 to an outlet connection 31. End members 25, 35, one on each side of the rotor 14, are secured to the cam ring 15. The end member 25 includes diametral pairs of ports, inner inlet ports 28a, outer inlet ports 28b, inner outlet ports 29a and outer outlet ports 29b, with the outlet ports disposed at 90 degrees with respect to the inlet ports. The end member 35 includes dimetral pairs of ports 48a, 48b, 49a, 49b corresponding to and aligned with the ports 28a, 28b, 29a, 29b with the outer inlet ports 28b, 48b interconnected by axial cam ring passages 64 and the outer outlet ports 29b, 49b inter-connected by axial cam ring passages 75. Liquid from the reservoir 30 passes through a passage 26 to the ports 28a and a branch passage 26a in which pressure is reduced to the ports 28b and thence through the passages 64 to the ports 48b. At the same time liquid from the reservoir 30 passes through an axial passage 13 and radial ports 66 in the shaft 13 and a passage 48 to the ports 48a, the pressure of the liquid in the ports 48a being increased by centrifugal force due to rotor rotation. Restricted ports 68 in the end member 35 convey liquid at reduced pressure to the ports 48b to supplement the liquid passing through the passages 64. It is stated that the ports and passages are designed to reduce the variation in radial pressures along the length of the rollers to reduce or eliminate tilting thereof. Pump discharge pressure is admitted to a chamber 54 at the rear of the end member 35 to urge the end member 35 into sealing engagement with the rotor and a flange 47 on the housing 11 sealingly against the end member. A spring-loaded, by-pass valve 70 when unseated by-passes liquid from the outlet passage 27 and directs it into the axial shaft passage 13a.