GB1178635A - Improved Rotary Positive-Displacement Hydraulic Pump - Google Patents

Abstract

1,178,635. Rotary positive-displacement pumps. CHRYSLER CORP. Nov.29, 1967 [Jan. 3, 1967(2)], No.54401/67. Heading F1F. A rotary positive-displacement hydraulic pump comprises a rotor 20, Figs.2 and 3, carrying a plurality of vanes in the form of rollers 23, which engage with the inner surface 24 of a cam ring 25 lodged between a fixed plate 26 and an axiallymovable pressure-loaded plate 27 within a housing 10 that also contains a spool valve-member 58 to regulate the rate of flow of hydraulic fluid through a delivery passage 75, Fig. 4, to e.g. a power steering gear (G), Fig. 1 (not shown), for an automobile, the rotor being mounted on a shaft 15 that is driven by a pulley 17 coupled to the engine of the automobile, and a reservoir 66 for the said fluid being defined by the housing and a shell 91 furnished with a removable cap 102. The plate 27 is pressed against the cam ring by a spring 35 and by the pressure of fluid in a chamber 36 communicating with outlet ports 55<SP>1</SP>, 56<SP>1</SP>, 55a<SP>1</SP>, 56a<SP>1</SP> in said plate, dummy outlet ports or balancing recesses 55, 56, 55a, 56a being formed in the plate 26 to effect hydraulic balancing of the rotor and the rollers. Fluid is discharged from the chamber 36 into the passage 75 through a port 37, a passage 69 and flow-restricting orifices 74, 77 within a fixed tubular insert 73. The fluid is drawn by the action of the rotor from the reservoir 66 through ducts 52, (65), Figs. 5 and 6 (not shown), which communicates with an end 51 of a chamber 50 circumjacent the cam ring and giving the fluid access to diametrally-opposed pairs of inlet ports (53, 54), (not shown in the drawings but referred to in the text) 53a, 54a, 53<SP>1</SP> , 54<SP>1</SP>, 53a<SP>1</SP> , 54a<SP>1</SP> in the plates aforesaid, the radially outermost of these ports being such that they offer slightly greater restriction to the flow of fluid as compared with the radially innermost ports and consequently the rollers in postions c and d are urged outwardly by a somewhat greater pressure that is communicated to their radially innermost sides through the adjacent ports, which pressure assists the normal centrifugal action. To reduce noise, the ports 56<SP>1</SP>, 56a<SP>1</SP> are furnished with tapering notches 104 at their leading edges. The pressure of fluid in the passage 75 is transmitted to a chamber 83, Fig. 4 through an orifice 82 in the valve member 58 so that when the pressure of fluid in the port 37 exceeds a predetermined value the valve member is moved axially against the action of a spring 59 to connect said port to the duct 52 that effects communication between the duct (65) and the end 51 of the chamber 50. The orifice 82 produces a dash-pot effect to minimize oscillation of the valve member. Excessive pressure in the chamber 83 is relieved by a non-return valve 86. Leakage fluid in a pocket 38 containing a bearing 39 for the shaft 15 escapes into the inlet port 54a<SP>1</SP> through a passage 103, a similar provision (not shown) being made for a seal 18 adjacent a further bearing 14. The housing 10 is pivotally secured to the engine of the automobile by a bracket 95 attached to a boss 97 and a pair of mounts 96, which are integral with the housing.