GB1390431A - Pumps particularly power steering pumps - Google Patents

Abstract

1390431 Rotary positive-displacement pumps T R W Inc 13 June 1972 [6 Oct 1971] 27598/72 Heading F1F A pump comprises a shaft 26 extending through a housing plate 21 and having a rotor 29 which carries slippers 33 engaging a cam 30 formed in a cam ring 31, there being upper and lower pressure plates 40, 36 contacting respective opposite sides of cam ring 31 and rotor 29, and a top plate 94 having an aperture 96 which receives a guide member 97, a space being defined between the bottom of aperture 96 and the member 97, this space being in communication with each working chamber via openings in the top and upper plates 94, 40 so that fluid pressure transmitted to the space serves to pressure load the upper plate 40 against cam ring 31. All these parts are surrounded by a cup-shaped member 115 having a flange 118 bolted to housing plate 21 and being attached by welds 120 to guide member 97. The whole is enclosed in a casing 125 sealingly connected at 131 to housing plate 21, screw 128 serving to attach casing 125 to guide member 97. A spring 102 serves to urge the stack of pump elements together. A valve member 86 is located in holes 73, 84, 56, 109 in the stack. The upper pressure plate 40, Fig. 13, has inlet ports 41a, 41b, 42a, 42b and outlet ports 43a, 43b, 44a, 44b. The lower side is recessed at 53, 54 and 56. A boss portion 47 receives valve 86. The distribution of inlet ports and outlet ports of the top plate, cam ring, lower pressure plate and housing plate can be easily distinguished in the respective Figs. 5, 3, 12 and 11. Casing 125 encloses a reservoir of fluid and communicates by inlets 122, 123, aspirators 80, 81 and by-pass passages 82, 83, Fig. 3, with the space between shell 115 and the stack of elements. This space acts as an inlet zone, fluid being drawn via recess 69, 70 in housing plate 21, and inlets 58, 58a, 57, 57a in lower plate 36 with the pumping chamber which discharges fluid to recess 56 in the upper plate 40. From recess 56 it passes through aperture 91 of valve 86 to chamber 109 in top plate 94 and thence via live outlets 110, 46, 79, 61, 71 to a pump outlet 110. Arrangements to ensure that the space between shell 115 and the pump stack can only communicate with the reservoir of casing 125 via the aspirators 80, 81 and by-pass passages 82, 83 are also described, Figs. 7 to 10, (not shown).