# US 2021/0277900 A1 · Dry vacuum pump and method for controlling a synchronous motor of a vacuum pump > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0277900 A1 - Document ID: US20210277900A1 - Status: Published application - Kind: A1 - Application number: 16/768,907 - Filed: 2018-12-05 - Published: 2021-09-09 - Earliest claimed: 2018-01-09 - Assignees: Pfeiffer Vacuum GmbH - Applicants: Pfeiffer Vacuum - Inventors: Yannick GRENIER; Didier PIERREJEAN; Jean-Marc PAGET - Web page: https://patentgrep.com/patent/US20210277900A1 ## CPC - F04C 25/02: for producing high vacuum (sealing arrangements F04C27/00; silencing F04C29/06) - F04C 18/12: of other than internal-axis type - F04C 18/126: {with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type} - F04C 23/02: Pumps characterised by combination with, or adaptation to, specific driving engines or motors - F04C 29/0042: {Driving elements, brakes, couplings, transmissions specially adapted for pumps (brakes, couplings, transmissions per se F16, B60)} - F04C 29/0085: {Prime movers} - H02K 1/2733: Annular magnets - H02K 7/14: Structural association with mechanical loads, e.g. with hand-held machine tools or fans (with fan or impeller for cooling the machine H02K9/06) - H02K 16/04: Machines with one rotor and two stators - F04C 2240/40: Electric motor - F04C 2270/02: Power - F04C 2270/60: Prime mover parameters - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract A dry vacuum pump is provided, including two shafts, respectively supporting at least one pumping rotor being configured to synchronously rotate in reverse in order to convey a gas to be pumped from an intake of the dry vacuum pump to an outlet; and a synchronous motor configured to rotate one shaft of the two shafts, the synchronous motor including a rotor coupled to the shaft, a first stator with windings arranged around the rotor, and at least one second stator with windings arranged around the rotor, the windings of the stators being configured to be supplied individually or simultaneously in order to adapt a power of the synchronous motor to a pumping load. A method for controlling a synchronous motor of a vacuum pump is also provided. ## Claims ### Claim at position 1 -14. (canceled) ### Claim 15 A dry vacuum pump, comprising: two shafts, respectively supporting at least one pumping rotor being configured to synchronously rotate in reverse in order to convey a gas to be pumped from an intake of the dry vacuum pump to an outlet; and a synchronous motor configured to rotate one shaft of the two shafts, the synchronous motor comprising: a rotor coupled to the shaft, a first stator with windings arranged around the rotor, and at least one second stator with windings arranged around the rotor, the windings of the stators being configured to be supplied individually or simultaneously in order to adapt a power of the synchronous motor to a pumping load. ### Claim 16 (depends on 15) The dry vacuum pump according to claim 15, wherein the windings of the stators are configured to be supplied individually when the pumping load of the dry vacuum pump is below a load threshold, and to be supplied simultaneously when the pumping load of the dry vacuum pump is greater than or equal to the load threshold. ### Claim 17 (depends on 15) The dry vacuum pump according to claim 15, wherein a power ratio between a power generated by the first stator and a power generated by the at least one second stator is between 1 and 10. ### Claim 18 (depends on 15) The dry vacuum pump according to claim 15, wherein the dry vacuum pump is a rough-vacuum pump comprising a plurality of pumping stages mounted in series, a power ratio between a power generated by the first stator and a power generated by the at least one second stator being between 1 and 5. ### Claim 19 (depends on 15) The dry vacuum pump according to claim 15, wherein the dry vacuum pump is a vacuum pump of the Roots type, which is configured to be connected to a chamber, in series and upstream of a rough-vacuum pump. ### Claim 20 (depends on 15) The dry vacuum pump according to claim 15, wherein the rotor comprises permanent magnets. ### Claim 21 (depends on 20) The dry vacuum pump according to claim 20, wherein at least one permanent magnet of the rotor is formed by a plurality of permanent magnet elements aligned along the rotor. ### Claim 22 (depends on 21) The dry vacuum pump according to claim 21, wherein the plurality of permanent magnet elements of the rotor only extend into the rotor facing the stators with the windings. ### Claim 23 (depends on 15) The dry vacuum pump according to claim 15, further comprising a first speed variator connected to the first stator with the windings, and a second speed variator connected to the at least one second stator with the windings. ### Claim 24 (depends on 23) The dry vacuum pump according to claim 23, further comprising: a control unit connected to the speed variators that is configured to supply the windings of the stators individually or simultaneously in order to adapt the power of the synchronous motor to the pumping load as a function of at least one signal representing the pumping load. ### Claim 25 (depends on 24) The dry vacuum pump according to claim 24, wherein the at least one signal representing the pumping load is a current-limiting output of one of the speed variators, representing a current consumed by the dry vacuum pump. ### Claim 26 (depends on 15) A method for controlling a synchronous motor of a dry vacuum pump according to claim 15, for pumping a chamber connected to the dry vacuum pump, wherein the windings of the stators are supplied individually when the pumping load of the dry vacuum pump is below a load threshold, and the windings are supplied simultaneously when the pumping load of the dry vacuum pump is above the load threshold, in order to adapt the power of the synchronous motor to the pumping load as a function of at least one signal representing the pumping load. ### Claim 27 (depends on 26) The method according to claim 26, wherein a most powerful of the two stators or both of the stators is supplied simultaneously upon start-up of the dry vacuum pump or in a step of discharging, starting from atmospheric pressure. ### Claim 28 (depends on 26) The method according to claim 26, wherein a step of discharging, starting from atmospheric pressure, and an ultimate vacuum pumping step occur cyclically inside the chamber.