GB1073216A - Improvements relating to swash plate pumps and motors - Google Patents

Abstract

1,073,216. Reciprocating pumps. F.W. BAGGETT & CO. Ltd. Nov.21, 1963 [Nov.21, 1962], No.44045/62. Heading F1A. [Also in Divisions F2 and G3] In a variable stroke pump or motor a swash plate 34, Fig. 1 is tiltably supported by trunnions (35), Fig. III (not shown) in hydrostatic bearings (36). A nitralloy block 4, Fig. 1, formed with cylinders 5 and extension sleeves 6 is mounted in white metal bearings 7 and splined at 22, 23 to shaft 8 which is mounted in needle bearing 10 and hydrostatic thrust bearing 12. When pressure oil is supplied through groove 18 and passageways 17 to recesses 16, the shaft end 11 is supported hydrostatically through collars 19 which are secured axially between piston rings 20 and nut 21. Trunnions (35), Fig. III (not shown) of swash plate 34 are carried hydrostatically in brackets (36) which have recesses (37) supplied with high pressure oil through pipes (38), connections (39), nozzles (109) and passages (40), (41). The tilting of swash plate 34 is controlled by a ram 42, sliding in a cylinder 44 supplied through a nozzle 45 with high pressure oil, and a ram 43 in which slides a servo-control spindle 52. High pressure oil from pipe (53), Fig. II (not shown) is supplied through part 54, groove 55 to a passage 56 on one side of groove 57 so that when spindle 52 is moved to the right in Fig. 1, gate 62 passes groove 57 allowing oil from passage 56 to pass through groove 57 and passages 58 to space 59 behind ram 43, which tilts the swash plate against the action of ram 42. When groove 57 moves to the right of gate 62, high pressure oil is no longer supplied to space 59 which is vented through passageways 58 and groove 57 through port 65, nozzle 64 and opening 66 into the interior of housing 1 which contains low pressure oil. Equilibrium is reached when gate 62 is in alignment with groove 57 so that oil is equally supplied to groove 57 through one recess 63 and vented out through the other recess into the housing interior. Servo-control spindle 52 may be manually operated or remotely operated through an electrical circuit which starts and stops on electrical motor 67 connected to spindle through a reduction gear-box 68, a shaft 69 and a pinion 70 meshing with rack 71. A sliding-vane type auxiliary pump 84, driven by shaft 8, draws in oil from a main reservoir through inlet 88 and port 89 and delivers it at low pressure through port 90 and coupling 92 to the inlet passage 94 of a combined pressure relief and oil distribution oil assembly. Passageway 94 extends around a hollow slide 95 and communicates through transverse gallery (96), Fig.V (not shown), both with outlets (97), (98), which contain non-return valves (99), (100), and with the main inlet or outlet ducts (74), (75), which in turn communicate through ports (73) Fig. II (not shown) in a hardened part plate 72 with the cylinders 5. The low pressure oil delivered from the auxiliary pump 84 opens the non-return valves (99) or (100) leading to either of the low pressure main ducts (74) or (75), depending on the direction of rotation of the cylinder block 4. In Fig. V the high pressure in duct (75) moves shuttle (101) to the right to communicate the high pressure to chamber (102) via passages (103), (104). Chamber (102) communicates through coupling 106, pipe 107, pipe 108 and through two pipes 38 to connections 39, through pipe 108 to groove 18, through pipe 53 to ram 43, and through nozzle 45 to ram 42. In normal working the high pressure in chamber 102 is communicated through a restricted passage in a slide 95, which is urged to the right as in Fig. 1, to passage 112, whilst chamber 119 communicates with the low pressure in gallery 96 through passage 120. Above a predetermined pressure ball valve 113 is unseated and the high pressure communicates through passage 120 with gallery 96. Oil flow through passage (111) causes slide 95 to move to the left against the action of spring 110 to put chamber 102 directly in communication with gallery 96 through passage 122 and hence with the low pressure main duct (74) or (75). In a modification applicable to machine tool drives, a shut-off valve (127), (not shown) Fig. VI is opened to exhaust space (59) through conduit (126) so that ram (43) does not balance ram (42) thus causing swash plate (34) to tilt until it engages bolt (124). When valve (127) is reclosed ram (43) tilts the swash plate back to its initial position determined by the practice of the servo control spindle (52).