# US 2018/0320691 A1 · High temperature pump unit with magnetic coupling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0320691 A1 - Document ID: US20180320691A1 - Status: Published application - Kind: A1 - Application number: 15/776,130 - Filed: 2016-11-16 - Published: 2018-11-08 - Earliest claimed: 2015-11-16 - Assignees: Grundfos Holding A/S - Applicants: Grundfos Holding A/S - Inventors: Flemming Buus Bendixen; Alan Ivo Sogaard Sorensen - Web page: https://patentgrep.com/patent/US20180320691A1 ## CPC - F04D 13/027: {Details of the magnetic circuit} - F04D 7/06: the fluids being hot or corrosive, e.g. liquid metals - F04D 13/06: the pump being electrically driven - H02K 49/106: {with a radial air gap} - H02K 2201/06: Magnetic cores, or permanent magnets characterised by their skew - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53}) ## Abstract The present invention relates to a pump unit (300), with at least one impeller, comprising a coupling, wherein the coupling is mechanically connected to the at least one impeller via an inner rotor and where an outer rotor is connected to an electrical machine arranged to produce a rotational torque, said pump being arranged to circulate a hot fluid by the impeller. The coupling includes an outer rotor including a plurality of permanent magnets (101,201) arranged to form a plurality of magnetic poles (105, 205), and an inner rotor (110, 210), whereby the outer rotor and the inner rotor are located coaxially to one another around an axis (130, 230) and spaced apart from one another by an air gap (150,250). A rotor can (330) is arranged in the air gap (250, 150) between the inner rotor and the outer rotor, so as to make a dividing section between the inner and outer rotor. Each of the plurality of magnetic poles comprises at least a section with a radial magnetic direction in respect of the axis (130, 230) and at least a section with a magnetic direction angled between a radial direction and a tangential direction in respect of the axis (130, 230), wherein the combined length of the sides of the plurality of permanent magnets cover less than 75% of the circumference of the cylindrical structure. The outer rotor has a cylindrical structure (120, 220) surrounding the plurality of magnetic poles (105, 205), and the cylindrical structure is made of a magnetic susceptible material for conducting a magnetic flux between the plurality of magnetic poles (105, 205) The inner rotor (110, 210) is made of a magnetic susceptible material and free from permanent magnetic material, wherein the inner rotor is formed with multiple radial projections (111, 211) acting as salient inner rotor poles distributed around the axis (130, 230) of the inner rotor. The invention also relates to a coupling with the above mentioned coupling features. ## Claims ### Claim 1 A pump unit (300) with at least one impeller (340), comprising a magnetic coupling (100, 200), wherein the coupling is mechanically connected to the at least one impeller via an inner rotor and where an outer rotor is connected to an electrical machine arranged to produce a rotational torque, said pump being arranged to circulate a fluid by the impeller, the magnetic coupling comprising an outer rotor including a plurality of permanent magnets (101,201) arranged to form a plurality of magnetic poles (105, 205); an inner rotor (110, 210); the outer rotor and the inner rotor being located coaxially to one another around an axis (130, 230) and spaced apart from one another by an air gap (150,250); a rotor can (330,662) arranged in the air gap (250, 150), between the inner rotor and the outer rotor, so to make a dividing section between the inner and outer rotor; the outer rotor has a cylindrical structure surrounding (120, 220) the plurality of magnetic poles (105, 205), the cylindrical structure being made of a magnetic susceptible material for conducting a magnetic flux between the plurality of magnetic poles (105, 205); and the inner rotor (110, 210) being made of a magnetic susceptible material and free of permanent magnetic material, wherein the inner rotor is formed with multiple radial projections (111, 210) acting as salient inner rotor poles distributed around the axis (130, 230) of the inner rotor; characterized in that, each of the plurality of magnetic poles, comprising at least a section with a radial magnetic direction in respect of the axis (130, 230) and at least a section with a magnetic direction angled between a radial direction and a tangential direction in respect of the axis (130, 230), wherein the combined length of the sides of the plurality of permanent magnets cover less than 75% of the circumference of the cylindrical structure. ### Claim 2 (depends on 1) The pump unit according to claim 1, wherein at least some of the plurality of permanent magnets (101,102,104) are covered fully or partly with a thermal protection layer. ### Claim 3 (depends on 1) The pump unit according to claim 1, wherein the plurality of permanent magnets are magnetized with sinusoidal magnetization. ### Claim 4 (depends on 1) The pump unit according to claim 1, wherein each of the plurality of magnetic poles are arranged as a Halbach array. ### Claim 5 (depends on 1) The pump unit according to claim 1, wherein the direction angled between a radial and a tangential direction is with an angle in the range of 20 to 70 degrees in respect of the radial direction. ### Claim 6 (depends on 1) The pump unit according to claim 1, wherein the inner rotor is made of a non-laminated material. ### Claim 7 (depends on 1) The pump unit according to claim 1, wherein the inner rotor (660) is encircled by a rotor sleeve (661). ### Claim 8 (depends on 1) The pump unit according to claim 1, wherein the rotor can (662) comprises a temperature-insulating layer. ### Claim 9 (depends on 1) The pump unit according to claim 1 wherein the permanent magnets (101-104) are fixated fully or partly by supporting material (260) placed in between two neighboring magnets (605a, 605b) in a place where no permanent magnetic material is present. ### Claim 10 (depends on 9) The pump unit according to claim 9 wherein the supporting material (260) placed in between two neighboring magnets is made of an electrical conducting and non-magnetic material, such as copper or aluminum. ### Claim 11 (depends on 9) The pump unit according to claim 9 wherein the supporting material is made of a first layer (261) and a second layer (262), wherein the first layer (261) is made of an electrical conducting and non-magnetic material and the second layer (262) is made of a magnetic susceptible material. ### Claim 12 (depends on 1) The pump unit according to claim 1, wherein the space (140, 240) between each of the multiple projections (111, 210) of the inner rotor is filled with an electrical conducting and non-magnetic material, such as copper or aluminum, forming a plurality elongated fillings, each of the elongated fillings are electrically connected to one another in both ends. ### Claim 13 (depends on 1) The pump unit according to claim 1, suitable for operating the inner rotor in a high temperature environment above 300 degrees Celsius. ### Claim 14 The pump unit according to 1, wherein the outer rotor comprises between two and eight magnetic poles, preferably four or six magnetic poles. ### Claim 15 The pump unit according to 1 wherein the number of magnetic poles of the outer rotor is different from the number of salient inner rotor poles. ### Claim 16 (depends on 1) The pump unit according to claim 1 wherein the inner rotor has four radial projections (111), and where each projection has a length in radial direction that is longer than the width of the projection, and where each projection protrudes from the axis (130,230) in a direction towards the outer rotor and defines a mechanical angle of 90 degrees with each of two neighboring projections. ### Claim 17 A magnetic coupling (100, 200) comprising an outer rotor including a plurality of permanent magnets, arranged to form a plurality of magnetic poles, each magnetic pole having a plurality of sections; an inner rotor made of a magnetic susceptible material and free of permanent magnetic material, wherein the inner rotor is formed with multiple radial projections acting as salient inner rotor poles distributed over a circumference of the inner rotor; the outer rotor (120,220) and the inner rotor (210, 110) being located coaxially to one another around an axis (230, 130) and spaced apart from one another by an air gap (250, 150); a rotor can (330, 662) arranged in the air gap (250, 150), between the inner rotor and the outer rotor, so to make a dividing section between the inner and outer rotor; the outer rotor has a cylindrical structure (120, 220) surrounding the plurality of magnetic poles, the cylindrical structure being made of a magnetic susceptible material for conducting a magnetic flux between the plurality of magnetic poles; each of the plurality of sections, comprising at least a section (101, 201) with a radial magnetic direction in respect of the axis (130, 203) and at least a section (102, 202) with a magnetic direction angled between a radial direction and a tangential direction in respect of the axis (130, 203); and wherein the combined length of the sides of the plurality of permanent magnets cover less than 75% of the circumference of the cylindrical structure.