MULTI-BLADE CENTRIFUGAL FAN AND AIR CONDITIONER EMPLOYING THE SAME

• US 20120211205A1
• Filed: 09/15/2010
• Published: 08/23/2012
• Est. Priority Date: 11/09/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Heavy Industries, Ltd.
• Original Assignee: Mitsubishi Heavy Industries, Ltd.
• Inventors: Eguchi, Tsuyoshi, Suzuki, Atsusi, Sato, Seiji, Takahashi, Masahiko
• Granted Patent: US 9,011,092 B2
• Time in Patent Office: Days
• US Class Current: 165/121
• CPC Class Codes: F04D 17/16 for displacing without appreciable compression
• CPC Class Codes: F04D 29/281 for fans or blowers
• CPC Class Codes: F04D 29/4226 Fan casings
• CPC Class Codes: F04D 29/441 especially adapted for elastic fluid pumps
• CPC Class Codes: F04D 29/681 especially adapted for elastic fluid pumps
• CPC Class Codes: F05D 2250/52 Outlet

Abstract

In a multi-blade centrifugal fan in which an impeller is provided in a scroll casing in a freely rotatable manner, the scroll casing is provided with an axially expanded portion that forms an air channel at a bottom surface thereof which is expanded in a rotation-axis direction at a radially outer side of an annular flange portion which supports the impeller; and is provided, in a region of an outlet between a tongue portion and a spiral-end portion of the scroll casing in the axially expanded portion, with a protrusion that protrudes radially outward from a radially inner side surface by a predetermined amount so as to directly face an airflow in a circumferential direction.

Claims

1. A multi-blade centrifugal fan comprising:

an impeller having numerous blades and provided in a freely rotatable manner in a scroll casing formed in a spiral shape with a tongue portion serving as its starting point, wherein

the scroll casing is provided with an axially expanded portion that forms an air channel that is expanded in a rotation axis direction at a radially outer side of an annular flange portion that supports the impeller at the bottom surface of the scroll casing; and

in a region of an outlet between the tongue portion and a spiral-end portion of the scroll casing in the axially expanded portion, a protrusion that protrudes radially outward from a radially inner side surface by a predetermined amount so as to directly face an airflow in a circumferential direction is provided.

2. A multi-blade centrifugal fan according to claim 1, wherein the height of the protrusion in the rotation axis direction is substantially the same as the height of the annular flange portion.

3. A multi-blade centrifugal fan according to claim 1, wherein the protrusion is integrally molded with a lower casing of the scroll casing by making a portion of an inner circumferential wall of an air channel inside the axially expanded portion, which is expanded in the rotation axis direction of the scroll casing, protrude inward in the air channel.

4. A multi-blade centrifugal fan according to claim 1, wherein, over an area from the vicinity of the tongue portion in the region of the outlet to an exit of a diffuser portion, the scroll casing is provided with multiple rows of rib-like protrusions so as to protrude along an airflow direction on a wall surface of the diffuser portion.

5. A multi-blade centrifugal fan according to claim 4, wherein the rib-like protrusions are integrally molded with the wall surface of the diffuser portion of the scroll casing.

14. An air conditioner in which a multi-blade centrifugal fan according to claim 1 is installed as a blower fan.

6. A multi-blade centrifugal fan comprising:

an impeller having numerous blades and provided in a freely rotatable manner in a scroll casing formed in a spiral shape with a tongue portion serving as its starting point, wherein

the scroll casing is provided with an axially expanded portion that forms an air channel that is expanded in a rotation axis direction at a radially outer side of an annular flange portion that supports the impeller at the bottom surface of the scroll casing; and

a sub-blade that simultaneously controls a secondary flow and the occurrence of turbulence in an airflow and vortices is provided along an airflow direction at a position closer to an inner circumferential side than a center portion of a wall surface of a diffuser portion in a region of an outlet in the axially expanded portion downstream of a spiral-end portion of the scroll casing.

7. A multi-blade centrifugal fan according to claim 6, wherein a top end of the sub-blade is substantially the same height as the annular flange portion of the scroll casing, and an area from an upstream end to a downstream end is kept at substantially the same height.

8. A multi-blade centrifugal fan according to claim 6, wherein the sub-blade is integrally molded with a wall surface of the diffuser portion in the region of the outlet downstream of the spiral-end portion of the scroll casing.

15. An air conditioner in which a multi-blade centrifugal fan according to claim 6 is installed as a blower fan.

9. A multi-blade centrifugal fan comprising:

an impeller having numerous blades and provided in a freely rotatable manner in a scroll casing formed in a spiral shape with a tongue portion serving as its starting point, wherein

the scroll casing is provided with an axially expanded portion that forms an air channel that is expanded in a rotation axis direction at a radially outer side of an annular flange portion that supports the impeller at the bottom surface of the scroll casing; and

a vortex control plate whose height in a rotation-axis direction is gradually increased over an area from upstream of the tongue portion to an inner circumferential side surface in a region of an outlet is provided near the tongue portion in the region of the outlet in the axially expanded portion downstream of a spiral-end portion of the scroll casing.

10. A multi-blade centrifugal fan according to claim 9, wherein the vortex control plate extends to a portion above the annular flange portion at the bottom surface of the scroll casing.

11. A multi-blade centrifugal fan according to claim 9, wherein a secondary-flow control plate that controls a secondary-flow at the diffuser portion is provided at an outer circumferential side surface which faces an inner circumferential side surface, that is, the side on which the vortex control plate is provided, in the region of the outlet over an area from the vicinity of the tongue portion to the exit of the diffuser portion.

12. A multi-blade centrifugal fan according to claim 11, wherein the height of a top end of the secondary-flow control plate is substantially the same height in an area from an upstream end to a downstream end thereof.

13. A multi-blade centrifugal fan according to claim 9, wherein the vortex control plate and the secondary-flow control plate are integrally molded with a lower casing of the scroll casing.

16. An air conditioner in which a multi-blade centrifugal fan according to claim 9 is installed as a blower fan.