# US 11,078,925 B2 · Vacuum pump and rotating cylindrical body included in vacuum pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,925 B2 - Document ID: US11078925B2 - Status: Granted - Kind: B2 - Application number: 16/327,154 - Filed: 2017-08-09 - Published: 2019-06-27 - Granted: 2021-08-03 - Earliest claimed: 2016-08-30 - Assignees: Edwards Japan Limited - Applicants: Edwards Japan Limited - Inventors: Yoshiyuki Sakaguchi; Tooru Miwata; Nahoko Yoshihara - Web page: https://patentgrep.com/patent/US11078925B2 ## CPC - F04D 29/526: {Details of the casing section radially opposing blade tips (ducts F04D29/545)} - F04D 3/00: Axial-flow pumps (priming or boosting F04D9/00) - F04D 19/042: {Turbomolecular vacuum pumps} - F04D 19/044: {Holweck-type pumps} - F04D 29/32: for axial flow pumps - F04D 29/403: {especially adapted for elastic fluid pumps} - F05D 2250/292: tapered - F05D 2250/52: Outlet - F05D 2260/941: particularly aimed at mechanical or thermal stress reduction - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A vacuum pump reduces a stress without reducing the rotation speed of a rotating cylindrical body. In an outlet port-side lower portion of a rotor cylindrical portion included in the vacuum pump, a smaller diameter portion having an outer diameter smaller than that of an inlet port-side portion of the rotor cylindrical portion is provided. A lowermost end portion (outlet port-side end portion) of the rotor cylindrical portion is designed longer than a thread groove exhaust element to provide an extending portion. In the extending portion, a smaller diameter portion having an outer diameter smaller than that of the inlet port-side portion of the rotor cylindrical portion which is opposed to the thread groove exhaust element is provided. ## Claims ### Claim 1 A vacuum pump comprising: a housing in which an inlet port and an outlet port are formed; a thread-groove exhaust mechanism which is fixed to the housing and has a thread groove; a rotating shaft which is rotatably supported and is enclosed in the housing; and a rotating cylindrical body which is disposed on the rotating shaft and includes an opposed portion opposed to the thread-groove exhaust mechanism via a gap and an extending portion extending downstream of a bottom surface of the thread-groove exhaust mechanism, the extending portion including a smaller-diameter portion having an outer diameter smaller than an outer diameter of the opposed portion, wherein an amount of diameter reduction in which an outer diameter of the extending portion is reduced is larger than an amount of diameter expansion in which an inner diameter of the extending portion is expanded. ### Claim 2 (depends on 1) The vacuum pump according to claim 1, wherein the extending portion includes a radially outer side surface of the smaller-diameter portion that terminates at a surface perpendicular to an axial direction of the rotating shaft, and an angle formed between the surface perpendicular to the axial direction and the radially outer side surface of the smaller-diameter portion is a right angle. ### Claim 3 (depends on 2) The vacuum pump according to claim 2, wherein a position of the surface perpendicular to the axial direction coincides with a position of a starting point of the extending portion. ### Claim 4 (depends on 3) A rotating cylindrical body included in the vacuum pump according to claim 3. ### Claim 5 (depends on 2) The vacuum pump according to claim 2, wherein the smaller-diameter portion is formed by providing a gradient in at least a portion of the extending portion located between a starting point and a terminal point thereof. ### Claim 6 (depends on 5) The vacuum pump according to claim 5, wherein a starting point of the gradient of the smaller-diameter portion coincides with the starting point of the extending portion. ### Claim 7 (depends on 6) A rotating cylindrical body included in the vacuum pump according to claim 6. ### Claim 8 (depends on 5) A rotating cylindrical body included in the vacuum pump according to claim 5. ### Claim 9 (depends on 2) A rotating cylindrical body included in the vacuum pump according to claim 2. ### Claim 10 (depends on 1) The vacuum pump according to claim 1, wherein the smaller-diameter portion is formed by providing a gradient in at least a portion of the extending portion located between a starting point and a terminal point thereof. ### Claim 11 (depends on 10) The vacuum pump according to claim 10, wherein a starting point of the gradient of the smaller-diameter portion coincides with the starting point of the extending portion. ### Claim 12 (depends on 11) A rotating cylindrical body included in the vacuum pump according to claim 11. ### Claim 13 (depends on 10) A rotating cylindrical body included in the vacuum pump according to claim 10. ### Claim 14 (depends on 1) A rotating cylindrical body included in the vacuum pump according to claim 1.