| 摘要 |
<p>#CMT# #/CMT# In an evacuation pumping device with primary force pump(s) (1) and secondary suction pump(s) (2) in series, driven by first and second electric motors (1b, 2b) with speeds modifiable by an electronic control module (3), the module has controllers which, as pressure in the chamber to be evacuated reduces, progressively increase and decrease the secondary and primary pump speeds respectively according to respective laws of variation (B) and (A). #CMT#USE : #/CMT# The device is useful for establishing and maintaining a specific degree of vacuum in a chamber, especially a vacuum chamber for use in industrial production of semiconductors (some stages of which must be carried out under vacuum). #CMT#ADVANTAGE : #/CMT# The chamber is evacuated rapidly (even in the case of large volume chambers, while minimizing overall energy consumption. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure shows a diagram of the general structure of one form of the vacuum pumping device. 1, 2 : Primary and secondary pumps 1b, 2b : First and second electric motors 1c, 2c : First and second energy suppliers 3 : Electronic control module 3a : Processor 3b : Memory 3c : Plot of variation of pumping speed as a function of pressure 3d : Plot of variation of pumping speed as a function of time 100 : Chamber to be evacuated 100a : Pressure sensor A, B : Laws of variation of pumping speeds for first and second pumps M : Motors P : Pressure V : Pumping speed #CMT#COMPUTING AND CONTROL : #/CMT# Preferred Features: The law of speed variation (B) of the secondary pump (2) comprises successive first, second and third stages of slow, rapid and medium increase respectively; and the law of speed variation (A) of the primary pump (1) comprises successive first, second and third stages of high speed, rapid decrease and slow decrease, the second stages of (B) and (A) preferably being simultaneous. The secondary pump has a higher nominal output than the first, specifically by a factor of 10-15. The speed controller comprises a first and second energy suppliers (1c, 2c) for the first and second motors (1b, 1c) respectively; and a processor (3a) with an associated memory (3b) containing a program for controlling the supplies to the motors on the basis of the laws of speed variation (A, B). At least one pressure sensor (100a) is provided for determining the pressure in the chamber (100) to be evacuated and supplying the signal to the processor.</p> |
