Pressure reduction system and vacuum treatment device

Abstract

A depressurization system includes a plurality of depressurization devices, each of which includes a cooling; and a compression device. The compression device includes a compression unit, which is provided with an AC electric motor, and supplies a compressed coolant to each cooling unit at a flow rate corresponding to a rotation speed of the AC electric motor. Each cooling unit supplements gas when adiabatically expanding the compressed coolant. The depressurization system also includes a temperature detection unit, which detects the temperature of each cooling unit, an inverter device, which is capable of changing a frequency of AC power supplies to the AC electric motor, and a frequency controller, which controls an output frequency of the inverter device. The frequency controller relatively raises the output frequency of the inverter device when the temperature of the cooling unit of at least one depressurization device of the depressurization devices is greater than or equal to a first threshold value, and relatively lowers the output frequency of the inverter device when the temperature of the cooling unit of all of the depressurization devices decreases to less than the first threshold value.

1 . A depressurization system comprising:
 a plurality of depressurization devices, each of which includes a cooling unit that receives a compressed coolant and is capable of supplementing gas when adiabatically expanding the compressed coolant;   a compression device including a compression unit provided with an AC electric motor, wherein the compression device supplies the compressed coolant to the cooling unit of each of the plurality of depressurization devices from the compression unit at a flow rate corresponding to a rotation speed of the AC electric motor;   a temperature detection unit that detects a temperature of the cooling unit of each depressurization device;   an inverter device capable of changing a frequency of AC power supplied to the AC electric motor; and   a frequency controller that controls an output frequency of the inverter device,   wherein the frequency controller relatively raises the output frequency of the inverter device when the temperature of the cooling unit of at least one of the plurality of depressurization devices is greater than or equal to a first threshold value, and relatively lowers the output frequency of the inverter device when the temperature of the cooling unit of all of the plurality of depressurization devices decreases to less than the first threshold value.   
     
     
         2 . The depressurization system according to  claim 1 , wherein the frequency controller
 acquires the temperature of the cooling unit of each depressurization device in each predetermined detection cycle, and   determines whether or not the temperature of the cooling unit of at least one depressurization device is greater than or equal to the first threshold value in each detection cycle and raises the output frequency of the inverter device.   
     
     
         3 . The depressurization system according to  claim 2 , wherein the frequency controller further determines whether the output frequency of the inverter device has been raised to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to the first threshold value and raises the output frequency if not. 
     
     
         4 . The depressurization system according to  claim 1 , wherein the frequency controller
 acquires the temperature of the cooling unit of each depressurization device for each predetermined detection cycle, and   determines whether or not the temperature of the cooling unit of all of the plurality of depressurization devices is less than the first threshold value for each detection cycle and lowers the output frequency of the inverter device.   
     
     
         5 . The depressurization system according to  claim 4 , wherein the frequency controller further determines whether the output frequency of the inverter device has been lowered to a lower limit value when the temperature of the cooling unit of at least one depressurization device is less than the first threshold value and lowers the output frequency if not. 
     
     
         6 . The depressurization system according to  claim 1 , wherein the frequency controller sets the output frequency of the inverter device to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to a second threshold value, which is greater than the first threshold value. 
     
     
         7 . A vacuum processing device comprising:
 a plurality of vacuum chambers; and   the depressurization system according to  claim 1 , wherein each of the plurality of vacuum chambers is connected to one of the plurality of depressurization devices.   
     
     
         8 . The depressurization system according to  claim 2 , wherein the frequency controller
 acquires the temperature of the cooling unit of each depressurization device for each predetermined detection cycle, and   determines whether or not the temperature of the cooling unit of all of the plurality of depressurization devices is less than the first threshold value for each detection cycle and lowers the output frequency of the inverter device.   
     
     
         9 . The depressurization system according to  claim 8 , wherein the frequency controller further determines whether the output frequency of the inverter device has been lowered to a lower limit value when the temperature of the cooling unit of at least one depressurization device is less than the first threshold value and lowers the output frequency if not. 
     
     
         10 . The depressurization system according to  claim 8 , wherein the frequency controller sets the output frequency of the inverter device to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to a second threshold value, which is greater than the first threshold value. 
     
     
         11 . The depressurization system according to  claim 3 , wherein the frequency controller
 acquires the temperature of the cooling unit of each depressurization device for each predetermined detection cycle, and   determines whether or not the temperature of the cooling unit of all of the plurality of depressurization devices is less than the first threshold value for each detection cycle and lowers the output frequency of the inverter device.   
     
     
         12 . The depressurization system according to  claim 11 , wherein the frequency controller further determines whether the output frequency of the inverter device has been lowered to a lower limit value when the temperature of the cooling unit of at least one depressurization device is less than the first threshold value and lowers the output frequency if not. 
     
     
         13 . The depressurization system according to  claim 11 , wherein the frequency controller sets the output frequency of the inverter device to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to a second threshold value, which is greater than the first threshold value. 
     
     
         14 . The depressurization system according to  claim 2 , wherein the frequency controller sets the output frequency of the inverter device to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to a second threshold value, which is greater than the first threshold value. 
     
     
         15 . The depressurization system according to  claim 4 , wherein the frequency controller sets the output frequency of the inverter device to an upper limit value when the temperature of the cooling unit of at least one depressurization device is greater than or equal to a second threshold value, which is greater than the first threshold value.