GB679607A - Improvements in high-vacuum molecular pumps - Google Patents

Abstract

679,607. Vacuum pumps. PHILIPS ELECTRICAL INDUSTRIES, Ltd., April 9, 1951 [April 12, 1952], No. 8178/51. Class 110(i) [Also in Group XXXIV] In a high - vacuum molecular pump comprising a rotor and a stator, one of which surrounds the other closely, the adjacent surfaces being conical and a continuous pumping groove being formed in one of the surfaces with a cross-section increasing towards the suction side, the bottom of the groove is at a constant distance from the axis of rotation. In the pump shown, a rotor 1 rotates between stators 3, 4, provided with helical grooves 5, 6. Air is sucked in at 7 and, after traversing the grooves 5, 6, enters a chamber 2, from which it passes by way of ports 9 to a discharge pipe 8. The rotor shaft 10 is journalled in ball bearings 11, 12 which are loaded by a spring 14. If the pressure at the inlet 7 increases suddenly, the resultant axial force on the rotor 1 causes it to move slightly against the action of the spring 14, thereby increasing the clearance between the rotor and stators sufficiently to permit a pressure interchange between the inlet and discharge of the pump. The clearance can be adjusted by means of a bolt 15. The rotor may comprise two or more walls cooperating with three or more grooves. The grooves may be provided in the rotor instead of in the stator. Instead of being helical, each groove may comprise a number of channels arranged at right angles to the axis of rotation and interconnected by inclined. channels.