Dry vacuum pump

Abstract

Between an exhaust chamber and a lubrication chamber, a second seal that seals between a cylinder that partitions the exhaust chamber and a first shaft and a first seal that seals between a side cover that partitions the lubrication chamber and the first shaft are provided. A gas introduction space to which a seal gas is supplied is provided between the second seal 2 and the first seal. The second seal and the first seal each have a base part and a pair of ring-like lips extending from the base part toward the first shaft. The pair of lips extends such that the distance therebetween is gradually increased from the base part toward the first shaft, and the tips of the pair of lips can be brought into elastic contact with the first shaft.

1 . A dry vacuum pump comprising:
 a shaft that is rotationally driven by an electromagnetic motor; and   rotors that are attached to the shaft and provided in an exhaust chamber and that suck an exhaust gas in a vacuum processing chamber into the exhaust chamber and discharge the exhaust gas,   wherein, between the exhaust chamber and a next chamber located next to the exhaust chamber, an exhaust-chamber-side seal that seals between an exhaust-chamber partitioning wall portion that partitions the exhaust chamber and the shaft and a next-chamber-side seal that seals between a next-chamber partitioning wall portion that partitions the next chamber and the shaft are provided;   a gas introduction space to which a seal gas is supplied is provided between the exhaust-chamber-side seal and the next-chamber-side seal;   the exhaust-chamber-side seal and the next-chamber-side seal each have a ring-like base part that is fixed to the exhaust-chamber partitioning wall portion or the next-chamber partitioning wall portion and a pair of ring-like lip parts that extends from the base part toward the shaft; and   the pair of lip parts extends such that the distance therebetween is gradually increased from the base part toward the shaft, and the tips of the pair of lip parts can be brought into elastic contact with the shaft.   
     
     
         2 . A dry vacuum pump according to  claim 1 , wherein the base part and the pair of lip parts are integrally structured. 
     
     
         3 . A dry vacuum pump according to  claim 1 , wherein the pair of lip parts is formed as individual members, and the base ends of the lip parts are fixedly combined to form the base part. 
     
     
         4 . A dry vacuum pump according to one of  claim 1 , wherein portions of the lip parts that are brought into contact with the shaft are made of polytetrafluoroethylene. 
     
     
         5 . A dry vacuum pump according to one of  claim 1 ,
 wherein an electromagnetic motor chamber that accommodates the electromagnetic motor is provided at a position where it sandwiches the next chamber with the exhaust chamber;   the next chamber is a lubrication chamber in which lubricating oil is stored; and   the exhaust gas includes hydrogen gas.   
     
     
         6 . A dry vacuum pump according to  claim 5 , wherein a gas discharge passage that is connected to an exhaust line to which the exhaust gas is discharged from the exhaust chamber is further provided, and an oil trap that traps the lubricating oil flowing toward the exhaust line is provided in the gas discharge passage. 
     
     
         7 . A dry vacuum pump according to one of  claim 1 , wherein a gas discharge passage that is connected to an exhaust line to which the exhaust gas is discharged from the exhaust chamber is further provided, and a check valve that permits a flow of gas flowing toward the exhaust line and prohibits a flow in the opposite direction is provided in the gas discharge passage. 
     
     
         8 . A dry vacuum pump comprising:
 an electromagnetic motor that is accommodated in an electromagnetic motor chamber;   a shaft that is rotationally driven by the electromagnetic motor; and   rotors that are attached to the shaft and provided in an exhaust chamber and that suck an exhaust gas including hydrogen gas in a vacuum processing chamber into the exhaust chamber and discharge the exhaust gas including hydrogen gas,   wherein purge means for introducing an inert gas into the electromagnetic motor chamber and for discharging a gas in the electromagnetic motor chamber is provided.   
     
     
         9 . A dry vacuum pump according to  claim 8 ,
 wherein a lubrication chamber in which lubricating oil is stored is provided between the exhaust chamber and the electromagnetic motor chamber; and   the inert gas introduced into the electromagnetic motor chamber by the purge means is discharged through the lubrication chamber.   
     
     
         10 . A dry vacuum pump comprising:
 an electromagnetic motor that is accommodated in an electromagnetic motor chamber;   a shaft that is rotationally driven by the electromagnetic motor;   rotors that are attached to the shaft and provided in an exhaust chamber and that suck an exhaust gas including hydrogen gas in a vacuum processing chamber into the exhaust chamber and discharge the exhaust gas including hydrogen gas; and   a lubrication chamber that is provided between the exhaust chamber and the electromagnetic motor chamber and in which lubricating oil is stored,   wherein purge means for introducing an inert gas into the lubrication chamber from outside the electromagnetic motor chamber through a gas introduction passage formed in the shaft and for discharging a gas in the lubrication chamber is provided.   
     
     
         11 . A dry vacuum pump according to  claim 8 ,
 wherein a lubrication chamber in which lubricating oil is stored is provided between the exhaust chamber and the electromagnetic motor chamber; and   the exhaust gas includes hydrogen gas.   
     
     
         12 . A dry vacuum pump according to  claim 9 , wherein the exhaust gas includes hydrogen gas. 
     
     
         13 . A dry vacuum pump according to  claim 11 , wherein the purge means includes a gas discharge passage that is connected to an exhaust line to which the exhaust gas is discharged from the exhaust chamber, and an oil trap that traps the lubricating oil flowing toward the exhaust line is provided in the gas discharge passage. 
     
     
         14 . A dry vacuum pump according to one of  claim 8 , wherein the purge means includes a gas discharge passage that is connected to an exhaust line to which the exhaust gas is discharged from the exhaust chamber, and a check valve that permits a flow of gas flowing toward the exhaust line and prohibits a flow in the opposite direction is provided in the gas discharge passage.