Fan unit with improved surge characteristics
AssigneeFisher & Paykel Healthcare Limited
InventorJohannes Nicolaas Bothma
Life of this patent
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Abstract
A fan unit that forms part of a gases supply unit used as part of a breathing assistance system for providing heated gases to a user. The fan has an impeller surrounded by an upwardly sloped surface to facilitate improved airflow performance under surge conditions.
Claims43
A fan unit which in use forms part of a gases supply unit suitable for use as part of a system for providing heated gases to a user, said fan unit comprising:
- a casing defining a diffuser, a volute, an inlet and an outlet, said volute further defined by a channel that encircles said diffuser,
- an impeller located within said casing and adapted for connection to a motor, said impeller further having an inducer adapted to receive a gases stream from said casing inlet, said diffuser located at least partially annular to said impeller, said impeller further having an exducer adapted to expel gases to said diffuser and said volute,
- a recirculation passage providing a gases flow path between an area proximate said exducer and an area proximate said inducer,
- wherein a lower surface of said diffuser and an inner wall of said volute define an angular transition of more than 270 degrees.
A fan unit which in use forms part of a gases supply unit suitable for use as part of a system for providing heated gases to a user, said fan unit comprising:
- a casing defining a diffuser, a volute, an inlet and an outlet, said volute further defined by a channel that encircles said diffuser,
- an impeller located within said casing and adapted for connection to a motor to rotate about an impeller axis, said impeller further having an inducer adapted to receive a gases stream from said casing inlet, said diffuser located at least partially annular to said impeller, said impeller further having an exducer adapted to expel gases to said diffuser and said volute,
- a recirculation passage providing a gases flow path between an area proximate said exducer and an area proximate said inducer,
- wherein airflow leaving said impeller is directed in a direction that is acute relative to the impeller axis and toward the entry of said passage.
A fan unit which in use forms part of a gases supply unit suitable for use as part of a system for providing heated gases to a user, said fan unit comprising:
- a casing defining a diffuser, a volute, an inlet and an outlet, said volute further defined by a channel having a radially expanding volume that surrounds said diffuser,
- an impeller located within said casing and adapted for connection to a motor to rotate about an impeller axis,
- said impeller further having at least one gases flow path entry to receive gases from said casing inlet and a gases flow path exit to expel gases to said diffuser, said volute and said casing outlet,
- a recirculation passage providing a gases flow path from an area proximate said impeller gases flow path exit to at least one said impeller gases flow path entry,
- wherein gases passed through said impeller are directed in a direction that is acute relative to the impeller axis and toward the entry of said passage.
Dependencies are inferred from the claim text.