# US 11,441,772 B2 · Forced-draft pre-mix burner device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,441,772 B2 - Document ID: US11441772B2 - Status: Granted - Kind: B2 - Application number: 16/039,399 - Filed: 2018-07-19 - Published: 2020-01-23 - Granted: 2022-09-13 - Earliest claimed: 2018-07-19 - Assignees: Brunswick Corporation - Applicants: Brunswick Corporation - Inventors: Stuart C. Black; Philip Eadie; Michael J. Biel - Web page: https://patentgrep.com/patent/US11441772B2 ## CPC - F23D 14/02: Premix gas burners, i.e. in which gaseous fuel is mixed with combustion air upstream of the combustion zone - F04D 17/16: for displacing without appreciable compression - F04D 23/008: {Regenerative pumps (for liquids or for liquids and elastic fluids F04D5/002)} - F04D 25/166: {using fans} - F23D 14/36: in which the compressor and burner form a single unit - F23D 14/62: Mixing devices; Mixing tubes - F23D 14/66: Preheating the combustion air or gas - F23L 5/02: Arrangements of fans or blowers - F23L 15/04: Arrangements of recuperators - F23N 2233/08: with variable speed - F23N 2241/14: Vehicle heating, the heat being derived otherwise than from the propulsion plant - F23D: BURNERS - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F23L: SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ({air-supply arrangements for fluent fuels F23C;} firebridges with means for feeding air or steam F23M3/04; baffles or shields with air supply passages F23M9/04); VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS {(dampers and throat restrictors for open fire-places F24; air inlet valves for open fire fronts F24)}; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES - F23N: REGULATING OR CONTROLLING COMBUSTION (control devices specially adapted for combustion apparatus in which combustion takes place in a fluidised bed of fuel or other particles F23C10/28; condition responsive controls for regulating combustion in domestic stoves with open fires for solid fuel F24B1/187) ## Abstract A forced-draft pre-mix burner device has a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet. A heat exchanger warms the air prior to discharge via the warm air outlet. A gas burner burns an air-gas mixture to thereby warm the heat exchanger. A fan mixes the air-gas mixture and forces the air-gas mixture into the gas burner. The fan has a plurality of blades having sinusoidal-modulated blade spacing. ## Claims ### Claim 1 A forced-draft pre-mix burner device comprising: a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet; a heat exchanger that warms the air prior to discharge via the warm air outlet; a gas burner that burns an air-gas mixture to thereby warm the heat exchanger; and a fan that mixes the air-gas mixture and forces the air-gas mixture into the gas burner, wherein the fan comprises a plurality of blades having sinusoidal-modulated blade spacing; wherein the fan further comprises an end cap having an end wall that faces the plurality of blades, an air-gas mixture inlet through which the air-gas mixture is conveyed to the plurality of blades, and an air-gas mixture outlet through which the air-gas mixture is conveyed to the gas burner; wherein the plurality of blades rotates about an axis of rotation extending in an axial direction, wherein the plurality of blades extends radially relative to the axial direction, wherein the end cap has a radial center located at the axis of rotation and a radial outer end that circumscribes the axis of rotation, and wherein air-gas mixture inlet and air-gas mixture outlet are formed through the end wall, radially between the radial center and the radial outer end; and wherein the air-gas mixture inlet is connected to the air-gas mixture outlet via a channel formed in the end wall and facing the plurality of blades in the axial direction, wherein the channel has a length extending from the air-gas mixture inlet to the air-gas mixture outlet, and wherein the channel gradually becomes shallower along an entirety of the length from the air-gas mixture inlet to the air-gas mixture outlet, so as to gradually introduce the air-gas mixture into the plurality of blades in the axial direction. ### Claim 2 (depends on 1) The forced-draft pre-mix burner device according to claim 1, wherein the plurality of blades comprises twenty-three blades that rotate about an axis of rotation. ### Claim 3 (depends on 2) The forced-draft pre-mix burner device according to claim 2, wherein the sinusoidal-modulated blade spacing has three modulation periods per fan revolution. ### Claim 4 (depends on 3) The forced-draft pre-mix burner device according to claim 3, wherein the plurality of blades comprises a maximum blade modulation angle of 4.6 degrees. ### Claim 5 (depends on 1) The forced-draft pre-mix burner device according to claim 1, wherein the plurality of blades has a forward angle so that the plurality of blades propels the air-gas mixture towards the gas burner. ### Claim 6 (depends on 1) The forced-draft pre-mix burner device according to claim 1, wherein the channel curves at least halfway around the axis of rotation from the air-gas mixture inlet to the air-gas mixture outlet. ### Claim 7 (depends on 6) The forced-draft pre-mix burner device according to claim 6, wherein the channel has a crescent shape with a narrow tip located at the air-gas mixture inlet. ### Claim 8 (depends on 7) The forced-draft pre-mix burner device according to claim 7, wherein the channel has an inlet end that gradually widens along the channel from the narrow tip. ### Claim 9 (depends on 6) The forced-draft pre-mix burner device according to claim 6, wherein the channel has a crescent shape with a narrow tip located at the air-gas mixture outlet. ### Claim 10 (depends on 9) The forced-draft pre-mix burner device according to claim 9, wherein the channel has an outlet end that gradually narrows towards the narrow tip. ### Claim 11 (depends on 1) The forced-draft pre-mix burner device according to claim 1, wherein the air-gas mixture inlet comprises a window formed through the end wall, the window facing radially inwardly towards the axis of rotation. ### Claim 12 (depends on 1) The forced-draft pre-mix burner device according to claim 1, wherein the channel extends around the radial center but does not radially overlap at the air-gas mixture inlet and air-gas mixture outlet. ### Claim 13 A forced-draft pre-mix burner device comprising: a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet; a heat exchanger that warms the air prior to discharge via the warm air outlet; a gas burner that burns an air-gas mixture to thereby warm the heat exchanger; and a fan that mixes the air-gas mixture and forces the air-gas mixture into the gas burner, wherein the fan comprises a plurality of blades having sinusoidal-modulated blade spacing and configured to rotate about an axis of rotation, wherein the plurality of blades radially extends relative to the axis of rotation, an end cap having an end wall that faces the plurality of blades, an air-gas mixture inlet formed through the end wall radially between the radial center and the radial outer end and through which the air-gas mixture is conveyed to the plurality of blades, an air-gas mixture outlet formed through the end wall radially between the radial center and the radial outer end and through which the air-gas mixture is conveyed to the gas burner, and a channel formed in the end wall and axially facing the plurality of blades, the channel having a length extending around the radial center from the air-gas mixture inlet to the air-gas mixture outlet, wherein the channel gradually becomes shallower along an entirety of the length from the air-gas mixture inlet to the air-gas mixture outlet, so as to gradually introduce the air-gas mixture axially into the plurality of blades. ### Claim 14 (depends on 13) The forced-draft pre-mix burner device according to claim 13, wherein the channel has a crescent shape with a narrow tip located at the air-gas mixture inlet. ### Claim 15 (depends on 14) The forced-draft pre-mix burner device according to claim 14, wherein the channel has an inlet end that gradually widens along the channel from the narrow tip. ### Claim 16 (depends on 13) The forced-draft pre-mix burner device according to claim 13, wherein the channel has a crescent shape with a narrow tip located at the air-gas mixture outlet. ### Claim 17 (depends on 16) The forced-draft pre-mix burner device according to claim 16, wherein the channel has an outlet end that gradually narrows towards the narrow tip. ### Claim 18 (depends on 13) The forced-draft pre-mix burner device according to claim 13, wherein the air-gas mixture inlet comprises a window formed through the end wall, the window facing radially inwardly towards the axis of rotation. ### Claim 19 (depends on 13) The forced-draft pre-mix burner device according to claim 13, wherein the channel extends around the radial center but does not radially overlap at the air-gas mixture inlet and air-gas mixture outlet. ### Claim 20 A forced-draft pre-mix burner device comprising: a housing that conveys air from an upstream cool air inlet to a downstream warm air outlet; a heat exchanger that warms the air prior to discharge via the warm air outlet; a gas burner that burns an air-gas mixture to thereby warm the heat exchanger; and a fan that mixes the air-gas mixture and forces the air-gas mixture into the gas burner, wherein the fan comprises a plurality of blades having sinusoidal-modulated blade spacing, wherein the plurality of blades rotates about an axis of rotation extending in an axial direction, and further wherein the plurality of blades extends radially relative to the axial direction, an end cap having an end wall that faces the plurality of blades, and an air-gas mixture inlet through which the air-gas mixture is conveyed to the plurality of blades and an air-gas mixture outlet through which the air-gas mixture is conveyed to the gas burner, wherein the air-gas mixture inlet is connected to the air-gas mixture outlet via a channel formed in the end wall, the channel facing the plurality of blades in the axial direction, and further wherein between the air-gas mixture inlet and the air-gas mixture outlet the channel gradually becomes shallower so as to gradually introduce the air-gas mixture into the plurality of blades in the axial direction as the air-gas mixture is conveyed along the channel.