COMPLETELY DRY AND FLUID-TIGHT VACUUM PUMPS

摘要

1367986 Rotary positive displacement pumps P VULLIEZ 30 May 1972 [1 June 1971 8 Sept 1971] 25278/72 Heading F1F A vacuum pump comprises a fixed disc 13' and a mobile disc 23' having co-operating spiral projections 13, 23, the mobile disc 23' performing circular translation movements relative to disc 13' so as to receive gas from a conduit 33 at the periphery of discs 13', 23' and to then compress the gas between the projections 13, 23 before delivering it from the centre of discs 13', 23' to the atmosphere via conduit 35. The fixed body 10, to which disc 13' is rigidly connected, carries three shafts 19 each having an eccentric portion 20 which engages, through bearings 22, the mobile disc 23'. The portions 20 have equal eccentricities E and are synchronized to provide the required circular translation of disc 23'. A central barrel 10', containing conduit 35, connects disc 13' to base 10" of body 10, the barrel 10' being surrounded by a bellows 11 which is sealingly connected via a bell-shaped member 28 to mobile disc 23' and via an annular member 30 to base 10". The bellows 11 thus seals the co-operating discs from the exterior. Cooling fluid is supplied by pump 40 and passes through conduits 41, 42 to a bulb 43 and the centre of spiral 13 and thence through conduit 44 to a bulb 45 in the centre of spiral 23. In operation, for a particular cycle, gas is drawn into the periphery of discs 13', 23' from conduit 33 which leads to the chamber to be evacuated. This process of suction occurs during a first revolution of disc 23' and at the end of it gas is trapped in volumes V 1 , Fig.2. A further revolution of disc 23' leads to compression of gas to the volumes V 2 and a still further revolution produces more compression, the two chambers being merged to a simple chamber V 3 . A final revolution of disc 23' causes the gas to be discharged through valve 34 and conduit 35 to the atmosphere. Alternatively Figs.4 and 5 (not shown) there can be two sets of co-operating spirals, the first having no bulbs and taking gas at the centre and discharges it peripherally to the second set which act as set out above. In a miniaturized version Figs. 6 and 7 (not shown) the vacuum pump is assisted by a diaphragm pump.