Patent GB-611416-A (GB)
Title: Improvements in or relating to rotary air pumps
IPC: F04C25/00
Filed: 1945-11-27
Abstract: 611,416. Rotary pumps; screw fans; substitutes for stuffing-boxes. BEST, C., and MOLINS MACHINE CO., Ltd. Nov. 27, 1945, No. 32033. [Classes 110 (i), 110 (ii) and 122 (v)] [Also in Group I] A rotary suction pump of the sliding vane-type in which liquid is employed to effect a seal and act as a lubricant comprises a water container having an outlet leading to the atmosphere and having passages for water leading from the container to apertures between the bearings and the rotor, the apertures having a close diametrical clearance with respect to parts rotating with the rotor so that water can filter into the pump chamber. The water container 13 communicates by means of passages 16, 17, Fig. 2, with spaces 12, Fig. 1, from which water flows through a close clearance between the spaces and the ends of the rotor to the pump chamber to provide sealing and lubrication. The clearance is about .002 inches on the diameter. Holes 18 are provided in the rotor to feed water to the vanes. Air is drawn in through a filter 59 and a sump 30, and a mixture of air and water is expelled into the container 13 by way of a tube 19 having downwardly directed holes 21. The air escapes to the atmosphere by way of a baffle plate 26, a non-return valve 25 and a diffuser 28. The latter prevents the escape of globules of water and preferably consists of knitted fabric. Noise due to pulsations is reduced by the presence of a volume of air above the level of the water in the container 13 and by the use of the valve 25 which prevents the pulsating return of air from the atmosphere. There may be a series of baffle plates 26. A non-return valve 31 may be fitted at the intake, and there may be baffling 70 to assist in keeping water out of the suction line. A lid 14, held in position by a clamp 15, allows the container to be refilled. A filter 40 may be provided. The height of water in the container 13 is shown by a gauge having a window 45 of transparent material such as that sold under the Registered Trade Mark " Perspex," provided on its inner face with a series of prismatic .grooves 46 which prevents the reflection of light and gives the water a dark appearance. A screen 47, preferably black in colour, prevents water from splashing on the window. The rotor vanes 9 are stepped to overlap one another and are pressed outwards by springs 10. Segmental packing pieces 11 are provided. The vanes and packing pieces are preferably of artificial graphite. The graphite may be reinforced by a steel framework around which it is moulded or inserted. To reduce relative motion between the two vanes the chamber bore may consist of two semi-circular arcs joined by two straight surfaces. A singlepiece diametrical vane may be used, in combination with a suitably shaped chamber wall. The rotor may be of stainless steel and the bush 3 may be of phosphor bronze. The outer race of one of the rotor shaft bearings is clamped in a bush 34 which is provided with an external thread engaging a threaded portion of the pump casing, whereby the longitudinal position of the rotor may be adjusted. Glands of the graphite ring type are provided at each end of the rotor shaft, sealing between each graphite ring 36 and the shaft being provided by a rubber washer 39. The glands may be of the kind described in Specification 611,503. Holes 44 are provided, through which water can drip, to indicate failure of a gland. Cooling is provided by fins 55 and by fan blades 56 fitted within the driving pulley 57. A modified filling arrangement for the water container comprises a funnel 50, Fig. 3, provided with a filter consisting of a porous cylindrical pot 54 of sintered bronze or other metal. To draw the water through the filter, the pipe leading therefrom is connected to the suction side of the pump, e.g. to the sump 30. A cock 53 is connected to the clamp 52 by a spindle 55 so that it is opened when the clamp is opened. Alternatively, the lid 51 may itself be pivoted about the spindle 55. According to the Provisional Specification, the pump chamber may be provided with a flexible liner which is distorted to the required non-circular shape by means of a system of wedges or screws.