Pumps – Successive stages – Reciprocating rigid stages
Patent
1987-02-27
1989-08-08
Freeh, William L.
Pumps
Successive stages
Reciprocating rigid stages
417266, 417493, 417267, 417DIG1, 92240, F04B 300, F04B 500, F04B 2502
Patent
active
048548251
ABSTRACT:
A vacuum pump includes two pairs of piston and cylinder assemblies mounted on opposite sides of a crankshaft in a common plane with the gas inlets for the first and second cylinders of a first pair of piston and cylinder assemblies being connected to the device to be evacuated and the gas outlets thereof being connected to a common outlet having a spring biased one-way valve controlling the outlet and to a passage connected to the inlet of a third cylinder in said second pair of piston and cylinder assemblies. The gas outlet of the third cylinder is connected to the inlet of the fourth cylinder and the gas outlet of the fourth cylinder is connected to the common outlet through spring biased one-way valves. Each cylinder is provided with a cylinder head having a pair of one-way valves controlling inlet and outlet ports wherein the one-way valve controlling the gas inlet port acts as a torque reduction valve to reduce the amount of torque necessary to move the piston away from the cylinder head on the initial stroke of the piston. Each cylinder is provided with a liner in the form of a sleeve having an hard wear resistant oxide coating thereon and each piston is provided with a coating of filled polytetrafluorethylene for the purpose of reducing friction.
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A High-Performance Oil-Free Backing Pump for Electron Microscopes published in Ninth International Congress on Electron Microscopy, Toronto, 1978, vol. 1.
A High-Performance Oil-Free Backing Pump for Electron Microscopes published by Ninth International Congress on Electron Microscopy, Toronto, 1978, vol. I.
Bez Eckhard
Farrant John L.
Commonwealth Scientific and Industrial Research Organization
Freeh William L.
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