US 11,815,096 B2
Pump unit
Eric Mandallaz, Annecy (FR); Thibaut Bourrilhon, Trevignin (FR); and Christophe Santi, Giez (FR)
Assigned to PFEIFFER VACUUM, Annecy (FR)
Appl. No. 17/626,634
Filed by PFEIFFER VACUUM, Annecy (FR)
PCT Filed Jun. 24, 2020, PCT No. PCT/EP2020/067619
§ 371(c)(1), (2) Date Jan. 12, 2022,
PCT Pub. No. WO2021/008834, PCT Pub. Date Jan. 21, 2021.
Claims priority of application No. 19 08088 (FR), filed on Jul. 17, 2019.
Prior Publication US 2022/0299030 A1, Sep. 22, 2022
Int. Cl. F04C 25/02 (2006.01); F04C 23/00 (2006.01); F04C 28/26 (2006.01); F04C 18/12 (2006.01); F04C 29/00 (2006.01)
CPC F04C 25/02 (2013.01) [F04C 18/126 (2013.01); F04C 23/001 (2013.01); F04C 28/26 (2013.01); F04C 29/0085 (2013.01); F04C 2220/12 (2013.01); F04C 2240/102 (2013.01); F04C 2240/20 (2013.01); F04C 2240/40 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A pump unit comprising:
a rough-vacuum pump; and
a Roots vacuum pump connected in series with and upstream of the rough-vacuum pump in a direction of flow of pumped gases,
wherein the Roots vacuum pump has three pumping stages in which the rotors are configured to be driven simultaneously in rotation by a motor of the Roots vacuum pump, and
wherein a ratio of a flow rate generated by a first pumping stage of the rough-vacuum pump in the direction of flow of the pumped gases over a flow rate generated by a last pumping stage of the rough-vacuum pump is less than or equal to four.