# US 9,752,582 B2 · Oil free screw compressor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,582 B2 - Document ID: US9752582B2 - Status: Granted - Kind: B2 - Application number: 15/186,775 - Filed: 2016-06-20 - Published: 2016-10-13 - Granted: 2017-09-05 - Earliest claimed: 2007-07-03 - Assignees: Hitachi Industrial Equipment Systems Co., Ltd. - Applicants: Hitachi Industrial Equipment Systems Co., Ltd. - Inventors: Hideki Fujimoto; Hitoshi Nishimura - Web page: https://patentgrep.com/patent/US9752582B2 ## CPC - F04C 29/04: Heating; Cooling (of machines or engines in general F01P); Heat insulation (heat insulation in general F16L59/00) - F04C 18/16: with helical teeth, e.g. chevron-shaped, screw type {(for non-parallel axes of movement F04C18/48)} - F04C 29/02: Lubrication (of machines or engines in general F01M); Lubricant separation (separation in general B01D) - F04C 29/12: Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet - F04C 2240/30: Casings or housings - F04C 2240/81: Sensor, e.g. electronic sensor for control or monitoring - F04C 2270/195: Controlled or regulated - F28D 2021/0049: {for lubricants, e.g. oil coolers} - F04C: ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS (engines F03C); ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS - F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of general) ## Abstract Provided is a highly reliable oil free screw compressor including a first sensor for detecting a temperature of lubrication oil, second sensors for detecting temperatures of intake air, and a cooling fan controller having a storage portion storing therein a set temperature of lubrication oil and a set temperature of intake air, and a computing portion for computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the lubrication oil, delivered from the first sensor, becomes higher than the set value of lubrication oil stored in the storage portion, and computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the intake air, delivered from the second sensor, becomes higher than the set temperature of the intake air, stored in the storage portion. ## Claims ### Claim 1 An oil free compressor comprising: a compressor body configured to compress intake air, a compressor housing, a compressed air discharge line provided in the compressor housing configured to discharge compressed air, a lubrication oil pipe line configured to flow lubrication oil, an air cooler configured to cool the compressed air flowing in the compressed air discharge line, an oil cooler configured to cool the lubrication oil flowing in the lubrication oil pipe line, a cooling fan configured to flow cooling air into the oil cooler and the air cooler, a cooling fan controller configured to: increase the rotating speed of the cooling fan if a temperature of the lubrication oil becomes higher than a predetermined temperature, and increase the rotating speed of the cooling fan if a temperature of the intake air becomes higher than a predetermined temperature. ### Claim 2 (depends on 1) The oil free compressor as set forth in claim 1, wherein the rotating speed of the cooling fan is controlled by an inverter exclusively used for the cooling fan. ### Claim 3 (depends on 1) The oil free compressor as set forth in claim 1, wherein the rotating speed of the cooling fan is controlled by an inverter used for the compressor. ### Claim 4 (depends on 1) The oil free compressor as set forth in claim 1, wherein the cooling fan controller receives temperatures of the inside of the compressor and temperatures of the outside of the compressor so as to control the rotating speed of the cooling fan. ### Claim 5 (depends on 1) The oil free compressor as set forth in claim 1, wherein the cooling fan controller receives a temperature in a control panel so as to control the rotating speed of the cooling fan. ### Claim 6 (depends on 1) The oil free compressor as set forth in claim 1, wherein a rotor of the compressor body is supported at least on one end by bearings, and the bearings are lubricated by lubricating oil flowing in the lubrication oil pipe line. ### Claim 7 (depends on 1) The oil free compressor as set forth in claim 1, wherein the compressor comprises at least two compressor bodies. ### Claim 8 (depends on 1) The oil free compressor as set forth in claim 1, wherein the compressor comprises at least a first stage compressor body and a second stage compressor body, and the compressed air discharge line provided in the compressor housing comprises: a first portion configured to: discharge compressed air from the first stage compressor body; and deliver the compressed air to the second stage compressor body; and a second portion configured to: discharge compressed air from the second stage compressor body; and deliver the compressed air outside the compressor housing. ### Claim 9 (depends on 8) The oil free compressor as set forth in claim 8, wherein the air cooler comprises a first cooler configured to cool compressed air flowing in the first portion of the compressed air discharge line and a second cooler configured to cool compressed air flowing in the second portion of the compressed air discharge line. ### Claim 10 (depends on 1) The oil free compressor as set forth in claim 1, further comprising a first sensor configured to detect a temperature of lubrication oil, which is provided in a position for detecting a temperature of lubrication oil in the lubrication oil pipeline downstream of the air cooling cooler to cool lubrication oil. ### Claim 11 (depends on 1) The oil free compressor as set forth in claim 1, further comprising a second sensor being provided in a position for detecting a temperature of intake air on a suction side of the compressor body, or being provided in a position for detecting a temperature compressed air flowing in the compressed air discharge line. ### Claim 12 (depends on 1) The oil free compressor as set forth in claim 1, wherein the compressed air discharge line discharges compressed air directly from the compressor body, and the compressed air discharged through the compressed air discharge line does not pass through a gear casing or an oil sump of the compressor body.