# US 7,744,342 B2 · Blower fan and working machine provided with the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,744,342 B2 - Document ID: US7744342B2 - Status: Granted - Kind: B2 - Application number: 11/294,967 - Filed: 2005-12-06 - Published: 2006-07-13 - Granted: 2010-06-29 - Earliest claimed: 2005-01-11 - Assignees: Yamabiko Corporation - Inventors: Tadashi Kamoshita; Tomoko Tada - Web page: https://patentgrep.com/patent/US7744342B2 ## CPC - F04D 25/02: Units comprising pumps and their driving means - F04D 29/4213: {suction ports} - F04D 29/665: {by means of resonance chambers or interference} - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) ## Abstract A blower fan includes: an impeller having a predetermined number of blades; a fan casing having an air-intake port disposed to face a central portion of base of the impeller and eccentrically housing the blower fan and defining a spiral scroll passageway between an inner wall thereof and an external circumference of the impeller, the spiral scroll passageway having an inlet portion constituting a narrow nose portion and an outlet portion constituting a wide discharge port; and a driving source for rotating the impeller. In order to minimize the noise to be released from the nose portion, the blower fan further includes a sound-reflecting means which is disposed to cover a portion of the air inlet port at a location spaced away from the nose portion by a distance corresponding to ½ of wavelength of noise in an emanating direction of noise. ## Claims ### Claim 1 A blower fan comprising: a circular impeller having a base and a predetermined number of curved blades radially arranged at equiangular intervals on the base; a fan casing having an air-intake port disposed to face a central portion of a substrate of the impeller and eccentrically housing the blower fan and defining a spiral scroll passageway between an inner wall thereof and an external circumference of the impeller, the spiral scroll passageway having an inlet portion comprising a narrow nose portion and an outlet portion which comprises a wide discharge port; a driving source for rotating the impeller; a narrow nose portion that is a noise source of said fan, wherein a force of air within the fan is most greatly compressed in the inside of the spiral scroll passageway; and a sound-reflecting member formed as a blind patch portion that covers part of the air intake port in order to minimize the noise to be released to the external environments from the narrow nose portion as a source of noise, where the blind patch portion is disposed at a position whose center is spaced away in an emanating direction of noise from the narrow nose portion by a distance corresponding to a half (½) of wavelength of noise. ### Claim 2 (depends on 1) The blower fan according to claim 1, wherein the sound reflecting member comprises a tray-shaped fan cover having a lattice-shaped framework provided with at least three air-intake openings and disposed to cover the air inlet port, wherein at least two of the air-intake openings are closed to form a blind patch. ### Claim 3 (depends on 2) The blower fan according to claim 2, wherein the sound-reflecting member is capable of varying in position correlating to the revolving speed of the impeller. ### Claim 4 (depends on 3) An air blast working machine comprising the blower fan of claim 3. ### Claim 5 (depends on 2) An air blast working machine comprising the blower fan of claim 2. ### Claim 6 (depends on 1) The blower fan according to claim 1, wherein the sound-reflecting member is capable of varying in position correlating to the revolving speed of the impeller. ### Claim 7 (depends on 6) An air blast working machine comprising the blower fan of claim 6. ### Claim 8 (depends on 1) An air blast working machine comprising the blower fan of claim 1. ### Claim 9 A blower fan comprising: a circular impeller having a base and a predetermined number of curved blades radially arranged at equiangular intervals on the base; a fan casing having an air-intake port disposed to face a central portion of a substrate of the impeller and eccentrically housing the blower fan and defining a spiral scroll passageway between an inner wall thereof and an external circumference of the impeller, the spiral scroll passageway having an inlet portion comprising a narrow nose portion and an outlet portion which comprises a wide discharge port; a driving source for rotating the impeller; a narrow nose portion that is a noise source of said fan, wherein a force of air within the fan is most greatly compressed in the inside of the spiral scroll passageway; and a sound-reflecting member made of a thin membrane, the sound-reflecting member being formed as a blind patch portion that covers part of the air intake port in order to minimize the noise to be released to the external environments from the narrow nose portion as a source of noise, where the blind patch portion is disposed at a position whose center is spaced away in an emanating direction of noise from the narrow nose portion by a distance corresponding to a half (½) of wavelength of noise. ### Claim 10 (depends on 9) The blower fan according to claim 9, wherein the sound reflecting member comprises a tray-shaped fan cover having a lattice-shaped framework provided with at least three air-intake openings and disposed to cover the air inlet port, wherein at least two of the air-intake openings are closed to form a blind patch. ### Claim 11 (depends on 10) The blower fan according to claim 10, wherein the sound-reflecting member is capable of varying in position correlating to the revolving speed of the impeller. ### Claim 12 (depends on 11) An air blast working machine comprising the blower fan of claim 11. ### Claim 13 (depends on 10) An air blast working machine comprising the blower fan of claim 10. ### Claim 14 (depends on 9) The blower fan according to claim 9, wherein the sound-reflecting member is capable of varying in position correlating to the revolving speed of the impeller. ### Claim 15 (depends on 14) An air blast working machine comprising the blower fan of claim 14. ### Claim 16 (depends on 9) An air blast working machine comprising the blower fan of claim 9.