# US 11,994,148 B2 · Centrifugal fan, air-sending device, air-conditioning apparatus, and refrigeration cycle apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,148 B2 - Document ID: US11994148B2 - Status: Granted - Kind: B2 - Application number: 17/287,826 - Filed: 2018-12-19 - Published: 2021-12-16 - Granted: 2024-05-28 - Earliest claimed: 2018-12-19 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Hiroyasu Hayashi; Takuya Teramoto; Kazuya Michikami; Ryo Horie; Takahiro Yamatani; Hiroshi Tsutsumi - Web page: https://patentgrep.com/patent/US11994148B2 ## CPC - F04D 29/4226: {Fan casings} - F04D 29/424: {Double entry casings} - F04D 29/441: {especially adapted for elastic fluid pumps} - F04D 29/663: {Sound attenuation} - F24F 7/007: with forced flow (using ducting systems F24F7/06) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02) ## Abstract A centrifugal fan includes a fan configured to be driven to rotate, and a scroll casing housing the fan. The scroll casing includes a peripheral wall having a volute shape having an inner end of a spiral thereof at a boundary with a tongue portion of the scroll casing. When a portion at the peripheral wall at which a distance between the peripheral wall and a rotation shaft of the fan is minimum is defined as a closest portion, the peripheral wall includes a narrowed portion at which the distance between the peripheral wall and the rotation shaft is reduced from the inner end toward the closest portion in a rotation direction of the fan, and an expanded portion that is formed between the narrowed portion and the closest portion and at which the distance between the peripheral wall and the rotation shaft is increased. ## Claims ### Claim 1 A centrifugal fan comprising: a fan configured to be driven to rotate; and a scroll casing housing the fan; the scroll casing including a peripheral wall having a volute shape having an inner end of a spiral thereof at a boundary with a tongue portion of the scroll casing, the tongue portion being configured to guide airflow generated by the fan, the peripheral wall including, when a portion at the peripheral wall at which a distance between the peripheral wall and a rotation shaft of the fan is minimum is defined as a closest portion, a narrowed portion at which the distance between the peripheral wall and the rotation shaft is reduced from the inner end toward the closest portion in a rotation direction of the fan, and an expanded portion that is formed between the narrowed portion and the closest portion and at which the distance between the peripheral wall and the rotation shaft is increased or the distance between the peripheral wall and the rotation shaft is constant. ### Claim 2 (depends on 1) The centrifugal fan of claim 1, wherein the scroll casing is configured such that, in a region from the inner end to the closest portion, a flow passage for gas formed between the peripheral wall and an outer peripheral portion of the fan is gradually narrowed at the narrowed portion, and the flow passage is then widened at the expanded portion. ### Claim 3 (depends on 1) The centrifugal fan of claim 1, wherein compared to a virtual reference peripheral wall configured such that the peripheral wall approaches the rotation shaft at a constant rate from the inner end toward the closest portion, the expanded portion expands in a radial direction of the fan. ### Claim 4 (depends on 1) The centrifugal fan of claim 1, wherein the peripheral wall includes, between the inner end and the closest portion, a first inflection portion defining a boundary portion between a part where the peripheral wall approaches the rotation shaft and a part where the peripheral wall separates from the rotation shaft, and a second inflection portion defining a boundary portion between the part where the peripheral wall separates from the rotation shaft and a part where the peripheral wall approaches the rotation shaft; and wherein the second inflection portion is located at the expanded portion. ### Claim 5 (depends on 4) The centrifugal fan of claim 4, wherein the peripheral wall is configured to gradually separate from the rotation shaft, from the first inflection portion to the second inflection portion. ### Claim 6 (depends on 1) The centrifugal fan of claim 1, wherein the peripheral wall includes a constant distance portion formed between the narrowed portion and the closest portion and at which the distance between the peripheral wall and the rotation shaft is constant. ### Claim 7 (depends on 6) The centrifugal fan of claim 6, wherein the peripheral wall includes, in a region from the inner end to the closest portion, a first inflection portion defining a boundary portion between a part where the peripheral wall approaches an outer peripheral portion of the fan and a part where a distance between the peripheral wall and the outer peripheral portion of the fan is constant, and a second inflection portion defining a boundary portion between the part where the distance between the peripheral wall and the outer peripheral portion of the fan is constant and a part where the peripheral wall approaches the outer peripheral portion of the fan; wherein the second inflection portion is located at the expanded portion; and wherein the constant distance portion is formed between the first inflection portion and the second inflection portion. ### Claim 8 (depends on 1) The centrifugal fan of claim 1, wherein the distance between the peripheral wall and the rotation shaft at the expanded portion is less than the distance between the peripheral wall and the rotation shaft at the inner end. ### Claim 9 (depends on 1) The centrifugal fan of claim 1, wherein the peripheral wall includes a protrusion protruding from an inner wall of the closest portion toward an inner side of the scroll casing. ### Claim 10 (depends on 9) The centrifugal fan of claim 9, wherein the protrusion is formed across the peripheral wall in a rotation axis direction of the fan. ### Claim 11 (depends on 9) The centrifugal fan of claim 9, wherein the protrusion is formed at part of the peripheral wall in a rotation axis direction of the fan. ### Claim 12 (depends on 9) The centrifugal fan of claim 9, wherein the protrusion is provided in plurality in a rotation axis direction of the fan. ### Claim 13 (depends on 9) The centrifugal fan of claim 9, wherein the protrusion is formed to have a thickness that is uniform in a rotation axis direction of the fan. ### Claim 14 (depends on 9) The centrifugal fan of claim 9, wherein the protrusion is formed to have a thickness that varies by location in a rotation axis direction of the fan. ### Claim 15 (depends on 1) An air-sending device comprising: the centrifugal fan of claim 1, and a case housing the centrifugal fan. ### Claim 16 (depends on 1) An air-conditioning apparatus comprising: the centrifugal fan of claim 1, and a heat exchanger disposed in a position facing an air outlet of the centrifugal fan. ### Claim 17 (depends on 16) The air-conditioning apparatus of claim 16, further comprising: a case housing the centrifugal fan and the heat exchanger, the case includes a case wall portion having a case air inlet through which gas that enters the centrifugal fan passes; wherein the closest portion is disposed between the case wall portion and a virtual plane portion passing through the rotation shaft and parallel to the case wall portion, in a cross-section perpendicular to the rotation shaft. ### Claim 18 (depends on 16) The air-conditioning apparatus of claim 16, further comprising: a case housing the centrifugal fan and the heat exchanger, the case includes a case wall portion having a case air inlet through which gas that enters the centrifugal fan passes; wherein when a line extending from the rotation shaft and perpendicular to the case wall portion is defined as a reference line, the closest portion is disposed between the reference line and the inner end, in a cross-section perpendicular to the rotation shaft. ### Claim 19 (depends on 1) A refrigeration cycle apparatus comprising: the centrifugal fan of claim 1.