Patent GB-1061088-A (GB)
Title: Improvements in or relating to pumps
IPC: F04C2/344
Filed: 1964-02-11
Abstract: 1,061,088. Rotary pumps; reciprocating pumps. TRW Inc. Feb. 11, 1964 [May 16, 1963], No.5692/64. Headings F1A and F1F. In a rotary pump of the outwardly-sliding vane or "slipper" type for a vehicle power-assisted steering system, the rotor 36, Fig.4, is lodged between a pair of pressure plates (24, 27), Fig. 2 (not shown), which in combination with a stationary abutment ring 33 defines a pumping chamber, the inner surface 34 of the ring being of substantially elliptic configuration to form two arcuate working- spaces 37, 38. Parallel-sided notches 46 in the periphery of the rotor contain sliding-rocking vanes or "slippers" 52 which are pressed against the ring 33 by compression springs 51. Each slipper is provided with an axially-orientated recess 58, to effect improved sealing, and a recess 59 at one end to give fluid access to spaces within the notches. Each of the notches has a recess 60 in one side thereof to provide relief for fluid trapped in the notch when it travels from one working space to the other. The rotor is attached to a driving shaft 92 which is supported by a single bearing (89, 90) lodged in the main body (30) of the pump housing, the rotor being mounted on the exterior of said bearing. The body (30) also contains a plate (29) which houses a flow-control valve, Fig. 11 (not shown), and is separated from the plate (27) by a plate (28). The plates (24, 27, 28, 29) and the ring 33 are aligned with one another by pins 66, 67 and pressed together by the pressure of fluid situated in an outlet chamber defined by the plate (29), the body (30) and a cap (32). A reservoir (101) is formed by a can (21) which has an inlet member (144) attached thereto and is secured by a discharge fitting (118) for the outlet chamber. In operation, fluid in the reservoir enters an adjacent inlet chamber 69 through an opening (102), Figs. and 5 (not shown) in the body (30) and passes into the spaces 37, 38 through notches or recesses (72), Fig. 6 (not shown), in the plate (24). Secondary inlet ports are provided in the plate (24) to give fluid access to the notches 46 whereby the pumping action is partly due to reciprocation of the slippers within the notches. Fluid is ejected by the slippers from the spaces 37, 38 and the notches 46 through ports (71, 75) in the plate (24), which ports are connected to similar ports (78, 79), Fig.7 (not shown), in the plate (27) by bores 61, 62 in the ring 33. Inlet recesses and ports (77, 80) are also provided in the plate (27). The ejected fluid passes through ports (82), Fig. 13 (not shown), in the plate (28) and a recess (104), Fig. 10 (not shown) in the plate (29) whence the fluid flows through an axiallyorientated passage (106) containing a pressurereducing orifice (107) which communicates with the outlet chamber. Communication between the passage (106) and a by-pass passage (123) is obstructed by the body (128) of the flow-control valve which is slidably lodged in the bore (120) within the plate (29) and pressed against a stop (126) by a spring (131). The passage (123) is connected to the inlet chamber 69 by a notch (83) in the plate (28). The body (128) houses a spring- biased valve (139), which normally closes a bore (137), and is provided with transverse bores (134) between lands (122, 130) which straddle the passage (123). The valve (139) serves to relieve excesspressure in the outlet chamber, the bore (137) being connected to said chamber by a passage (132). The pressure-drop across the orifice (107) effects a pressure-difference between the fluid in the passage (106) and that in the bore (120), whereby an increase in the rate of flow causes the body (128) to be depressed against the action of the spring (131) and allow an appropriate proportion of fluid in the passage (106) to pass through the by-pass passage (123) into the inlet chamber 69. In a modification, Fig. 12 (not shown), fluid in the recess (104) is ejected directly into the outlet chamber (108) without passing through an orifice. The fluid leaves the chamber (108) through a first orifice (158) in a tube (156) attached to an outlet nipple (155) and rendered in communication with the flow-control valve (161) by a second orifice (159). Fluid entering the tube (156) from the chamber (108) effects a pressure drop across the orifice (158) and a corresponding pressuredifference at the flow-control valve.