| 摘要 |
PCT No. PCT/FR89/00494 Sec. 371 Date Aug. 14, 1990 Sec. 102(e) Date Aug. 14, 1990 PCT Filed Sep. 27, 1989 PCT Pub. No. WO90/07061 PCT Pub. Date Jun. 28, 1990.A pumping assembly for obtaining a high vacuum, the assembly comprising a primary pump (4) and a secondary pump (1) associated in series, the inlet of the secondary pump (1) being taken from an enclosure (3) to be evacuated, the assembly further including means (7) for starting the secondary pump (1) when the pressure upstream from the primary pump (4) drops below a value P1, the assembly being characterized in that a passive tank (10) followed by an isolating valve (11) are interposed between the outlet (12) from the secondary pump (1) and the inlet (13) to the primary pump (4), and in that it includes control means (7) for closing the isolating valve (11) and stopping the primary pump (4) when the pressure in said passive tank (10) reaches a value P2<P1, and for opening the isolating valve (11) and restarting the primary pump (4) when the pressure in said passive tank ( 10) returns to the pressure P1.
|
