Controller of vacuum pump

Abstract

A vacuum pump has a pump mechanism section that performs evacuation to set a space to be evacuated to a predetermined degree of vacuum and an electric motor section for driving the pump mechanism section. A controller of the vacuum pump executes deceleration control to decrease a rotational speed of the electric motor section when an increase in load torque of the vacuum pump per unit time abruptly changes upward.

1 . In a controller of a vacuum pump having a pump mechanism section that performs evacuation to set a space to be evacuated to a predetermined degree of vacuum, the improvement comprising an electric motor section for driving said pump mechanism section, 
 wherein, when an increase in load torque of said vacuum pump per unit time abruptly changes upward, deceleration control to decrease a rotational speed of said electric motor section is carried out.    
   
   
       2 . The controller according to  claim 1 , wherein said load torque of said vacuum pump is calculated based on a value of a current supplied to said electric motor section.  
   
   
       3 . The controller according to  claim 1 , wherein said increase in load torque of said vacuum pump per unit time is monitored repeatedly at a predetermined time interval and that monitoring is continued even after it is determined that said increase in load torque of said vacuum pump per unit time has increased abruptly.  
   
   
       4 . The controller according to  claim 1 , wherein, when said increase in load torque of said vacuum pump per unit time is greater than a predetermined value, it is determined that said increase in load torque of said vacuum pump per unit time has abruptly changed upward and said deceleration control is carried out.  
   
   
       5 . The controller according to  claim 1 , wherein, when a rate of change in said increase in load torque of said vacuum pump per unit time is greater than a predetermined value, it is determined that said increase in load torque of said vacuum pump per unit time has abruptly changed upward and said deceleration control is carried out.  
   
   
       6 . The controller according to  claim 4 , wherein said deceleration control is carried out to reduce said increase in load torque of said vacuum pump per unit time to a predetermined target value.  
   
   
       7 . The controller according to  claim 5 , wherein said deceleration control is carried out to reduce a rate of change in said increase in load torque of said vacuum pump per unit time to a predetermined target value.  
   
   
       8 . The controller according to  claim 1 , wherein said electric motor section is controlled in such a way that said load torque of said vacuum pump does not exceed a predetermined upper limit.  
   
   
       9 . The controller according to  claim 1 , wherein said electric motor section includes a synchronous motor type or inductive motor type brushless motor.  
   
   
       10 . The controller according to  claim 1 , wherein a load-lock chamber provided side-by-side with respect to a process chamber in a semiconductor production apparatus is said space to be exhausted by said vacuum pump.  
   
   
       11 . The controller according to  claim 1 , wherein said increase in load torque of said vacuum pump per unit time is monitored repeatedly at a predetermined time interval, and that monitoring is stopped after it is determined that said increase in load torque of said vacuum pump per unit time has abruptly changed upward.  
   
   
       12 . The controller according to  claim 11 , wherein a number of times said deceleration control is repeated is restricted.  
   
   
       13 . (canceled)  
   
   
       14 . A method for controlling evacuation of a space to predetermined degree of vacuum, the method comprising: 
 using an electric motor to drive a pump mechanism to evacuate the space;    monitoring the load torque of said vacuum pump per unit time; and    when the load torque abruptly changes upward, performing deceleration control to reduce the rotational speed of said electric motor.    
   
   
       15 . A controller of controlling evacuation a space to a predetermined degree of vacuum, the controller comprising: 
 a pump mechanism section that performs evacuation and an electric motor section for driving said pump mechanism section,    wherein, when an increase in load torque of said vacuum pump per unit time abruptly changes upward, deceleration control to decrease a rotational speed of said electric motor section is carried out.    
   
   
       16 . The controller according to  claim 15 , wherein said load torque of said vacuum pump is calculated based on a value of a current supplied to said electric motor section.  
   
   
       17 . The controller according to  claim 15 , wherein said increase in load torque of said vacuum pump per unit time is monitored repeatedly at a predetermined time interval and that monitoring is continued even after it is determined that said increase in load torque of said vacuum pump per unit time has increased abruptly.  
   
   
       18 . The controller according to  claim 15 , wherein, when said increase in load torque of said vacuum pump per unit time is greater than a predetermined value, it is determined that said increase in load torque of said vacuum pump per unit time has abruptly changed upward and said deceleration control is carried out.  
   
   
       19 . The controller according to  claim 15 , wherein, when a rate of change in said increase in load torque of said vacuum pump per unit time is greater than a predetermined value, it is determined that said increase in load torque of said vacuum pump per unit time has abruptly changed upward and said deceleration control is carried out.  
   
   
       20 . The controller according to  claim 18 , wherein said deceleration control is carried out to reduce said increase in load torque of said vacuum pump per unit time to a predetermined target value.  
   
   
       21 . The controller according to  claim 19 , wherein said deceleration control is carried out to reduce a rate of change in said increase in load torque of said vacuum pump per unit time to a predetermined target value.