US 11,732,722 B2
Vacuum pump
Masashi Manabe, Kyoto (JP)
Assigned to SHIMADZU CORPORATION, Kyoto (JP)
Filed by SHIMADZU CORPORATION, Kyoto (JP)
Filed on Sep. 17, 2022, as Appl. No. 17/947,098.
Claims priority of application No. 2021-159080 (JP), filed on Sep. 29, 2021; and application No. 2022-012172 (JP), filed on Jan. 28, 2022.
Prior Publication US 2023/0096958 A1, Mar. 30, 2023
Int. Cl. F04D 19/04 (2006.01); F04D 29/00 (2006.01)
CPC F04D 19/042 (2013.01) [F04D 29/002 (2013.01); F05D 2210/12 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A vacuum pump comprising:
a housing having an inlet port for sucking gas and an outlet port for discharging the sucked gas;
a rotor cylindrical portion housed in the housing; and
a stator cylindrical portion housed in the housing and arranged to face the rotor cylindrical portion,
wherein a screw groove is formed on one of opposing surfaces of the stator cylindrical portion and the rotor cylindrical portion,
a groove depth of the screw groove is smaller at an end on an exhaust side than at an end on a suction side, and
a decrement of the groove depth is greater on the suction side than on the exhaust side,
the screw groove has
a first portion of which decrement of the groove depth is constant, and
a second portion which is arranged on the exhaust side with respect to the first portion and of which decrement of the groove depth is constant,
the decrement at the first portion is greater than the decrement at the second portion,
the first portion and the second portion are connected to each other at a decrement change portion, and
when the groove depth at an end of the first portion on the suction side is Da,
the groove depth at an end of the second portion on the exhaust side is Db, and
the groove depth at the change portion is Dc,
Db≤Dc≤(Da+Db)×0.5 is satisfied.