Patent GB-729247-A (GB)
Abstract: 729,247. Rotary pumps. ROBOURN-EATON MANUFACTURING CO., Ltd. Dec., 5, 1952 [Dec. 14, 1951], No. 30933/52. Class 10 (2). A rotary pump 11 on which is mounted a reservoir 12 is provided with delivery and return conduits 13, 14 forming part of a closed circuit 15 which may include hydraulicallyoperated steering mechanism 16. Through the rotor chamber 19 extends a drive shaft 20. which rotates meshing gear members 24, 25. The outer gear member 24 is rotatably supported by a bushing 26 and the inner gear 26 is keyed to the shaft 20. Fluid is supplied simultaneously to each pumping chamber 28 through arcuate intake ports 29, 30 on opposite sides of the rotor chamber 19 and is discharged from the pumping;.chambers through discharge ports. 31, 32 arranged on opposite sides of the rotor chamber. The discharge port 31 communicates with the conduit 13 through a valve chamber 33, Fig. 6. Fluid is supplied from the reservoir to the intake port 29 through a passage 37 and to the intake port 30 it passes from the return conduit 14 through an axial passage 38 in the shaft 20, radial openings 40 in the shaft communicating with an annular chamber 39 and,thenc.e with connecting passage 41 in the pump housing 17a. The .supply passage connecting the return conduit 14 with passage 38 also communicates with the reservoir through a vertical, passage 44, dir.t and air bubbles being removed from the fluid before return to the passage 37 by a strainer 47. To control the delivery pressure, by-pass means are provided which comprise a volume control valve 50 in the valve chamber 33 and a pressure relief valve 51 in a valve chamber 52 as described in Specification 719,359. The volume control valve means includes an annular valve seat 53 intermediate the intake and discharge ports 29, 31, Fig. 6, a valve plunger portion 54 and a dashpot plunger 55 connected by an axial stem 56. The valve, chamber 33 is closed at the upper end by a spring-pressed plug 58 forming a seat for a compression spring 60. A flow control orifice 61 allows fluid from ,the discharge port 31 to pass through the valve 50 to the delivery conduit 13. The areas of the valve 50 exposed to fluid pressure and the pressure of the spring 60 are such that the required volume is discharged through the orifice 61, excess fluid being by-passed to the intake port 29 by movement of the plunger 54. The pressure relief valve chamber 52 communicates with the intake port 29 through an opening 62 and with the discharge port 31 through an opening 63. Between the openings 62, 63 is a valve seat 64 co-operating with a portion 65 of the valve plunger 51 slidable in the chamber 52, which is closed by a plug 68 held in place by a spring ring 69 and bearing on a compression spring 70. The areas of the valve plunger 51 exposed to fluid pressure and the pressure of the spring 70 are such that the valve functions to by-pass fluid from the discharge port 31 to the intake port 29 when the pressure in the discharge conduit reaches a maximum value. An annular sealing device 71 around the shaft 20 closes the outer end of the annular chamber 39 in which collects fluid leaking from the rotor chamber around the shaft for return to the intake 30 through the passage 41. The chamber 39 is kept filled by fiow from the supply passage 43, thus leakage from the rotor chamber is counteracted and leakage of air between the shaft and the packing 71 prevented. A modification of the pump is described.