GB832264A - Improvements in or relating to vacuum pumping apparatus - Google Patents

Abstract

832,264. Rotary vacuum pumps. N.G.N. ELECTRICAL Ltd. May 6, 1958 [May 6, 1957], No. 14371/57. Class 110 (2). The pump submerged in oil 28 is of the type described in Specification 825,524 in which an outwardly-sliding abutment 21 with its cylindrical root 18 pivoted in a recess 17 on the edge of a piston 12, has one part X sliding around the circular bore 16 of a pumping chamber. Apparatus to admit oil and air (or other gas) to the working chamber simultaneously comprises valves 27, 38, respectively, Fig. 1, or a valve 61, Fig. 2. The piston 12 is actuated by an eccentric 14 carried by a shaft 15. An inlet port 22 and a vertical series of outlet holes 23 are provided for the working chamber. A non- return valve 24 of synthetic rubber has a longitudinal slit in it, overlying the ports 23. A plunger 36, when lifted, allows oil to flow into the working chamber through a port 27. A further plunger 38 is lifted to open a port 29 and allow the inflow of air from the atmosphere by way of a port 39. A knob 43, on a crosshead 42, is used to lift or lower the oil and air plunger valves simultaneously. In Fig. 2, a needle valve 59 controls the air admission to a port 51, in the pump chamber, by way of a non- return valve 61 containing a duct 67. A recess 71 allows the inflow of oil when it lines up with a duct leading from the oil supply 69.