Pump apparatus

Abstract

A pump apparatus in accordance with the present invention is used to discharge a process gas from, for example, a semiconductor manufacturing system, and is constructed so that a rotor is pivotally supported by a magnetic bearing. To decrease the solidification and deposition of process gas in a tube of the pump apparatus, heat is generated in a bearing electromagnet of magnetic bearing to keep the temperature of tube at a high temperature. Heat is generated in the bearing electromagnet, for example, by causing a bias current to flow together with a control current, or by causing a high frequency current to flow. Also, a motor is heated by repeating the increase and decrease of rotational speed of motor, whereby the temperature of tube can be raised.

What is claimed is:  
     
         1 . A pump apparatus comprising: 
 a casing formed with a gas intake port on one end side thereof and a gas discharge port on the other end side thereof;    a base member forming a bottom on the other side of said casing;    a cylindrical member which is fixed to said base member and contains a bearing and a motor;    a rotor shaft which is rotatably contained in said cylindrical member via said bearing and is rotated by said motor;    a rotor disposed on said rotor shaft;    a stator disposed on the inner peripheral surface of said casing with a predetermined space provided with respect to said rotor;    gas transfer means formed in the space between said rotor and said stator; and    heat generation control means for controlling the amount of heat generated in said cylindrical member.    
     
     
         2 . The pump apparatus according to  claim 1 , wherein 
 said bearing is a magnetic bearing, and    said heat generation control means controls a bias current superimposed on a control current of said magnetic bearing.    
     
     
         3 . The pump apparatus according to  claim 1 , wherein 
 said bearing is a magnetic bearing, and    said heat generation control means controls a high frequency current superimposed on a control current of said magnetic bearing.    
     
     
         4 . The pump apparatus according to  claim 1 , wherein 
 said heat generation control means controls the amount of generated heat of said motor by changing the rotational speed of said motor.    
     
     
         5 . The pump apparatus according to  claim 2 , wherein 
 said heat generation control means controls the amount of generated heat of said motor by changing the rotational speed of said motor.    
     
     
         6 . The pump apparatus according to  claim 3 , wherein 
 said heat generation control means controls the amount of generated heat of said motor by changing the rotational speed of said motor.    
     
     
         7 . The pump apparatus according to  claim 1 , wherein 
 said cylindrical member, said base member, said rotor, and said stator are formed of aluminum or aluminum alloy.    
     
     
         8 . The pump apparatus according to  claim 2 , wherein 
 said cylindrical member, said base member, said rotor, and said stator are formed of aluminum or aluminum alloy.    
     
     
         9 . The pump apparatus according to  claim 3 , wherein 
 said cylindrical member, said base member, said rotor, and said stator are formed of aluminum or aluminum alloy.    
     
     
         10 . The pump apparatus according to  claim 4 , wherein 
 said cylindrical member, said base member, said rotor, and said stator are formed of aluminum or aluminum alloy.    
     
     
         11 . The pump apparatus according to  claim 7 , wherein 
 a reinforcing member disposed around said motor or a housing member for said bearing is formed of aluminum or aluminum alloy.    
     
     
         12 . The pump apparatus according to  claim 1 , wherein 
 at least a part of opposing surfaces of said stator and said rotor is coated to enhance heat radiation efficiency.    
     
     
         13 . The pump apparatus according to  claim 2 , wherein 
 at least a part of opposing surfaces of said stator and said rotor is coated to enhance heat radiation efficiency.    
     
     
         14 . The pump apparatus according to  claim 3 , wherein 
 at least a part of opposing surfaces of said stator and said rotor is coated to enhance heat radiation efficiency.    
     
     
         15 . The pump apparatus according to  claim 1 , wherein 
 at least a part of the outer peripheral surface of said cylindrical member is opposed to the inner peripheral surface of said rotor with a predetermined space there between, and    at least a part of opposing surfaces of said cylindrical member and said rotor is coated to enhance heat radiation efficiency.    
     
     
         16 . The pump apparatus according to  claim 2 , wherein 
 at least a part of the outer peripheral surface of said cylindrical member is opposed to the inner peripheral surface of said rotor with a predetermined space there between, and    at least a part of opposing surfaces of said cylindrical member and said rotor is coated to enhance heat radiation efficiency.    
     
     
         17 . The pump apparatus according to  claim 3 , wherein 
 at least a part of the outer peripheral surface of said cylindrical member is opposed to the inner peripheral surface of said rotor with a predetermined space there between, and    at least a part of opposing surfaces of said cylindrical member and said rotor is coated to enhance heat radiation efficiency.    
     
     
         18 . The pump apparatus according to  claim 1 , wherein 
 said pump apparatus further comprises: 
 cooling means formed in said pump apparatus; and  
 cooling control means for controlling said cooling means in relation to a temperature detected by temperature detecting means provided at a predetermined location of said pump apparatus.  
   
     
     
         19 . The pump apparatus according to  claim 2 , wherein 
 said pump apparatus further comprises: 
 cooling means formed in said pump apparatus; and  
 cooling control means for controlling said cooling means in relation to a temperature detected by temperature detecting means provided at a predetermined location of said pump apparatus.  
   
     
     
         20 . The pump apparatus according to  claim 3 , wherein 
 said pump apparatus further comprises: 
 cooling means formed in said pump apparatus; and  
 cooling control means for controlling said cooling means in relation to a temperature detected by temperature detecting means provided at a predetermined location of said pump apparatus.