Vacuum-generating pumping system and pumping method using this pumping system

Abstract

The present invention relates to a pumping system to generate a vacuum (SP), comprising a main vacuum pump which is a dry screw pump ( 3 ) having a gas suction inlet ( 2 ) connected to a vacuum chamber ( 1 ) and a gas discharge outlet ( 4 ) leading into a gas evacuation conduit ( 5 ) in the direction of a gas exhaust outlet ( 8 ) outside the pumping system. The pumping system comprises a non-return valve ( 6 ) positioned between the gas discharge outlet ( 4 ) and the gas exhaust outlet ( 8 ), and an auxiliary vacuum pump ( 7 ) connected in parallel to the non-return valve. In a pumping method by means of this pumping system (SP), the main vacuum pump ( 3 ) is started up in order to pump the gases contained in the vacuum chamber ( 1 ) and to discharge these gases through its gas discharge outlet ( 4 ), simultaneously to which the auxiliary vacuum pump ( 7 ) is started up. Moreover the auxiliary vacuum pump ( 7 ) continues to pump all the while that the main vacuum pump ( 3 ) pumps the gases contained in the vacuum chamber ( 1 ) and/or all the while that the main vacuum pump ( 3 ) maintains a defined pressure in the vacuum chamber ( 1 ).

1 . Pumping system for generating a vacuum, comprising a main vacuum pump which is a dry screw pump having a gas suction inlet connected to a vacuum chamber and a gas discharge outlet leading into a gas evacuation conduit in the direction of a gas exhaust outlet outside the pumping system,
 the pumping system being characterized in that it comprises   a non-return valve positioned between the gas discharge outlet and the gas exhaust outlet, and   an auxiliary vacuum pump connected in parallel to the non-return valve.   
     
     
         2 . Pumping system according to  claim 1 , characterized in that the auxiliary vacuum pump is selected from among a dry screw pump, a claw pump, a multi-stage Roots pump, a diaphragm pump, a dry rotary vane pump and a lubricated rotary vane pump. 
     
     
         3 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump is a dry screw pump. 
     
     
         4 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump is a claw pump. 
     
     
         5 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump is a multi-stage Roots pump. 
     
     
         6 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump is a diaphragm pump. 
     
     
         7 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump a dry rotary vane pump. 
     
     
         8 . Pumping system according to  claim 2 , characterized in that the auxiliary vacuum pump is a lubricated rotary vane pump. 
     
     
         9 . Pumping system according to  claim 1 , characterized in that the auxiliary vacuum pump is designed to be able to pump all the while that the main vacuum pump pumps the gases contained in the vacuum chamber and/or all the while that the main vacuum pump maintains a defined pressure in the vacuum chamber. 
     
     
         10 . Pumping system according to  claim 1 , characterized in that the auxiliary vacuum pump comprises a discharge end which is connected downstream from the non-return valve, to the gas evacuation conduit. 
     
     
         11 . Pumping system according to  claim 1 , characterized in that nominal flow rate of the auxiliary vacuum pump is selected as a function of the volume which the gas evacuation conduit delimits between the main vacuum pump ( 3 ) and the non-return valve. 
     
     
         12 . Pumping system according to  claim 1 , characterized in that the nominal flow rate of the auxiliary vacuum pump is from 1/500 to 1/20 of the nominal flow rate of the main vacuum pump. 
     
     
         13 . Pumping system according to  claim 1 , characterized in that the auxiliary vacuum pump is single-staged or multi-staged. 
     
     
         14 . Pumping system according to  claim 1 , characterized in that the non-return valve is configured to close when the pressure at the suction end of the main vacuum pump is less than 500 mbar absolute. 
     
     
         15 . Pumping system according to  claim 1 , characterized in that the auxiliary vacuum pump is made of materials having high chemical resistance to substances and gases commonly used in the semi-conductor industry. 
     
     
         16 . Pumping method by means of a pumping system according to  claim 1 , characterized in that
 the main vacuum pump is started up in order to pump the gases contained in the vacuum chamber and to discharge these gases through its gas discharge outlet;   simultaneously the auxiliary vacuum pump is started up; and   the auxiliary vacuum pump continues to pump all the while that the main vacuum pump pumps the gases contained in the vacuum chamber and/or all the while that the main vacuum pump maintains a defined pressure in the vacuum chamber.   
     
     
         17 . Pumping method according to  claim 16 , characterized in that the auxiliary vacuum pump pumps <at> a flow rate on the order of 1/500 to 1/20 of the nominal flow rate of the main vacuum pump. 
     
     
         18 . Pumping method according to  claim 16 , characterized in that the non-return valve closes when the pressure at the suction end of the main vacuum pump is less than 500 mbar absolute.