# US 10,309,697 B2 · Cooling system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,697 B2 - Document ID: US10309697B2 - Status: Granted - Kind: B2 - Application number: 15/347,423 - Filed: 2016-11-09 - Published: 2018-05-10 - Granted: 2019-06-04 - Earliest claimed: 2016-11-09 - Assignees: Aktiebolaget Skf - Applicants: Aktiebolaget SKF - Inventors: Rudolf Hauleitner; Mario Kammerhuber; Guillermo Morales Espejel; Hans Wallin - Web page: https://patentgrep.com/patent/US10309697B2 ## CPC - F25B 31/004: {oil recirculating arrangements} - F25B 2400/07: Details of compressors or related parts - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract A cooling system includes a refrigerant compressor and a first operating medium, which provides a mixture of refrigerant and lubrication oil. An oil separator reduces the percentage of the refrigerant in the operating medium to a value between 15% by weight and 60% by weight. ## Claims ### Claim 1 A cooling system, comprising: a refrigerant compressor, and an oil separator configured to separate a combined operating medium comprising a mixture of a refrigerant and a lubrication oil into a first operating medium and a second operating medium, wherein the second operating medium comprises between 15% by weight and 60% by weight of the refrigerant, so that the second operating medium is lubrication oil enriched compared to the first operating medium, wherein the refrigerant compressor is configured to compress at least a portion of the first operating medium, wherein the second operating medium has a viscosity ratio of κ<1 in a first operating state of the cooling system and serves for lubricating at least one bearing site of a rotor of the refrigerant compressor, wherein the at least one bearing site comprises at least one angular ball bearing, which comprises an inner ring, an outer ring and balls rolling therebetween, and wherein at least a first ball comprises a ceramic. ### Claim 2 (depends on 1) The cooling system according to claim 1, wherein the ceramic is silicon nitride Si3N4. ### Claim 3 (depends on 1) The cooling system according to claim 1, wherein the refrigerant includes derivatives of alkenes. ### Claim 4 (depends on 1) The cooling system according to claim 1, wherein the refrigerant includes Hydrofluorooelfins (HFOs) and/or Hydrochlorofluorooelfins (HCFOs). ### Claim 5 (depends on 1) The cooling system according to claim 1, wherein the oil separator is configured to provide the second operating medium having between 20% by weight and 40% by weight of the refrigerant. ### Claim 6 (depends on 1) The cooling system according to claim 1, wherein a joint operating medium circuit of the first and second operating medium is provided, wherein the at least one bearing site is sealed against the first operating medium. ### Claim 7 (depends on 1) The cooling system according to claim 1, wherein the angular ball bearing comprises at least a plurality of second balls having a surface which is softer than the surface of the first ball. ### Claim 8 (depends on 1) The cooling system according to claim 1, wherein the angular ball bearing comprises an inner ring, an outer ring and balls rolling between, wherein the inner ring and/or the outer ring have a nitrided or carbonitrided raceway. ### Claim 9 (depends on 8) The cooling system according to claim 8, wherein the angular ball bearing comprises an inner ring, an outer ring and balls rolling between, wherein the inner ring and/or the outer ring have a burnished raceway. ### Claim 10 (depends on 1) The cooling system according to claim 1, wherein the at least one bearing site comprises at least a second bearing, wherein the second bearing is a cylindrical roller bearing. ### Claim 11 (depends on 10) The cooling system according to claim 10, wherein the second bearing comprises an inner ring, an outer ring and balls rolling therebetween, wherein at least a first ball comprises a ceramic. ### Claim 12 (depends on 11) The cooling system according to claim 11, wherein the ceramic is silicon nitride Si3N4. ### Claim 13 (depends on 1) The cooling system according to claim 1, wherein, during operation of the cooling system, the refrigerant compressor is operated with variable rotational speeds. ### Claim 14 (depends on 1) The cooling system according to claim 1, wherein the viscosity ratio of the second operating medium is κ>1 in a second operating state of the cooling system, the second operating state corresponding to a higher rotational speed of the refrigerant compressor, a lower temperature thereof, or both as compared to the first operating state. ### Claim 15 (depends on 1) The cooling system according to claim 1, further comprising a condenser configured to condense the operating medium, wherein the oil separator is downstream from the condenser and upstream from the refrigerant compressor. ### Claim 16 (depends on 1) The cooling system according to claim 1, further comprising a condenser configured to condense the operating medium, wherein the oil separator is integrated into the condenser. ### Claim 17 (depends on 1) The cooling system according to claim 1, wherein the oil separator is configured to decrease a refrigerant composition of the second operating medium in response to a decrease in temperature at the at least one bearing site. ### Claim 18 A method, comprising: separating, using an oil separator, a combined operating media comprising refrigerant and lubrication oil, to produce a first operating medium and a second operating medium, the second operating medium having a refrigerant content of between 15% by weight and 60% by weight and being lubrication oil enriched as compared to the first operating medium; lubricating at least one bearing site of a refrigerant compressor using the second operating medium, wherein the second operating medium in the at least one bearing site has a viscosity ratio of κ<1 when the refrigerant compressor is in a first operating state, wherein the bearing site comprises at least one angular ball bearing, which comprises an inner ring, an outer ring and balls rolling therebetween, and wherein at least a first ball comprises a ceramic; compressing at least the first operating medium by operating the refrigerant compressor in the first operating state; mixing the first and second operating media to produce the combined operating media; and feeding the combined operating media to the oil separator. ### Claim 19 (depends on 18) The method of claim 18, further comprising cooling the mixture of the first and second operating media in a condenser that is upstream of the oil separator and downstream from the refrigerant compressor. ### Claim 20 (depends on 18) The method of claim 18, further comprising increasing the refrigerant content of the second operating medium in response to a decrease in temperature at the at least one bearing site, to decrease the viscosity ratio of the second operating medium at the at least one bearing site.