US20200063748A1

US20200063748A1 - Centrifugal blower and method of assembling the same

Info

Publication number: US20200063748A1
Application number: US16/107,555
Authority: US
Inventors: Alan Jacob Manz; Steven W. Post
Original assignee: Regal Beloit America Inc
Current assignee: Regal Beloit America Inc
Priority date: 2018-08-21
Filing date: 2018-08-21
Publication date: 2020-02-27

Abstract

A centrifugal blower assembly with reduced recirculation losses includes a housing defining an interior space and at least one inlet ring coupled to the housing to define an inlet into the interior space. The centrifugal blower assembly also includes an impeller configured to rotate about an axis to channel an airflow through the inlet and within the interior space. The impeller includes a plurality of blades that each include a notch formed therein, wherein the notch is radially aligned with the at least one inlet ring.

Description

BACKGROUND

The field of the disclosure relates generally to centrifugal blowers, and more specifically, to centrifugal blowers that include an impeller that improves blower efficiency and reduces blower noise.
Centrifugal blowers or fans are commonly used in the automotive, air handling, and ventilation industries for directing large volumes of forced air, over a wide range of pressures, through a variety of air conditioning components. In some known centrifugal blowers, air is drawn into the blower housing through one or more inlet openings by an impeller, which defines an inlet chamber. At least some centrifugal blowers include a relatively large air gap between the inlet ring and the end of the blades of the impeller. The larger the air gap between the impeller blades and the inlet ring, the less efficient the operation of the impeller wheel. However, at least some air gap is desired to allow for manufacturing variations and impeller displacement when the blower system is subjected to external shock.

BRIEF DESCRIPTION

In one aspect, a centrifugal blower assembly is provided. The centrifugal blower assembly includes a housing defining an interior space and at least one inlet ring coupled to the housing to define an inlet into the interior space. The centrifugal blower assembly also includes an impeller configured to rotate about an axis to channel an airflow through the inlet and within the interior space. The impeller includes a plurality of blades that each include a notch formed therein, wherein the notch is radially aligned with the at least one inlet ring.
In yet another aspect, a method of assembling a centrifugal blower assembly is provided. The method includes providing a housing that defines an interior space and positioning an impeller within the housing such that the impeller is configured to rotate about an axis to channel an airflow within the interior space. The impeller includes a plurality of blades that each include a notch formed therein. The method also includes coupling an inlet ring to the housing to define an inlet into the interior space, wherein the inlet ring is radially aligned with each notch of the plurality of blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of an exemplary centrifugal blower;

FIG. 2 is a cross-sectional view of the centrifugal blower shown in FIG. 1;

FIG. 3 is a perspective view of an exemplary impeller wheel and inlet rings for use with the centrifugal blower shown in FIG. 1;

FIG. 4 is a cross-sectional view of the impeller wheel and inlet rings shown in FIG. 3;

FIG. 5 is an enlarged cross-sectional view illustrating an exemplary notched blade of the impeller wheel;

FIG. 6 is an enlarged cross-sectional view illustrating an alternative embodiment of a notched blade of the impeller wheel;

FIG. 7 is an enlarged cross-sectional view illustrating another alternative embodiment of a notched blade of the impeller wheel; and

FIG. 8 is an enlarged cross-sectional view illustrating yet another alternative embodiment of a notched blade of the impeller wheel.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.

DETAILED DESCRIPTION

The apparatus, methods, and systems described herein provide a centrifugal blower having increased efficiency due to a reduction in recirculation losses. More specifically, the impeller described herein includes a plurality of blades that each include a notch formed at the convergence of each blade's leading edge and axial end. The notch is radially aligned in the blower assembly with an inlet ring to reduce the distance between the inlet ring and the blades, as compared to known blower assemblies. In some embodiments, the inlet ring extends axially beyond an end ring of the impeller and into the notch on the blade such that the inlet ring axially overlaps with a portion of the blade. Including the notch on the blades reduces the distance between the axial end of the inlet ring and the blade to reduce recirculation losses and increase efficiency. The notches create a “seal” between the impeller and the inlet ring to reduce the amount of air leaking between the impeller and the inlet ring and bypassing the impeller. Additionally, the notches create clearance for manufacturing tolerances and for impeller displacement should the blower assembly be subjected to external shock to prevent inlet ring-impeller striking. As such, the notches enable a longer blade to reduce recirculation, while also allowing for potential impeller displacement.
FIG. 1 is a schematic perspective view of an exemplary centrifugal blower assembly 10. FIG. 2 is a cross-sectional view of centrifugal blower assembly 10. In the exemplary embodiment, centrifugal blower assembly 10 includes a fan impeller 12 having an axis of rotation 14. Fan impeller 12 is coupled to a motor 16, which is configured to rotate fan impeller 12 about axis of rotation 14. In one embodiment, motor 16 is an axial flux electric motor. In an alternative embodiment, motor 16 is a radial flux electric motor. The rotation of fan impeller 12 draws air into centrifugal blower assembly 10 along axis of rotation 14 as represented by airflow arrows 100, and expels the air radially outward into a housing 18. In the exemplary embodiment, fan impeller 12 is formed from a plurality of forward curved fan blades 20. Alternatively, fan blades 20 may include backward curved blades, airfoil blades, backward inclined blades, radial blades, or any other suitable blade shape that enables fan impeller 12 to operate as described herein. In the exemplary embodiment, the shape of fan blades 20 of fan impeller 12 facilitates reducing operating noise of fan impeller 12. Fan impeller 12 is configured to produce a flow of air for a forced air system, e.g., without limitation, a residential HVAC system.
In the exemplary embodiment, housing 18 includes a first sidewall 22 and an opposite second sidewall 24. Sidewalls 22 and 24 are fabricated as generally flat, parallel sidewalls disposed at axially opposite ends of fan impeller 12. An outer periphery 26 of each of sidewalls 22 and 24 is shaped substantially the same and generally forms a volute shape with respect to axis of rotation 14. In the exemplary embodiment, blower assembly 10 further includes a scroll wall 28. More specifically, scroll wall 28 is coupled to outer periphery 26 of sidewalls 22 and 24 thereby forming an increasing expansion angle for airflow 100 through housing 18. In the exemplary embodiment, scroll wall 28, which extends around fan impeller 12, includes a cutoff portion 30 including a cutoff point 32 that is at least partially disposed within an interior space 34 of housing 18. Interior space 34 is defined at least by sidewalls 22 and 24 and by scroll wall 28.
In the exemplary embodiment, housing 18 includes an air inlet opening 36 provided in first sidewall 22 and another air inlet opening in second sidewall 24. Specifically, in the exemplary embodiment, a respective inlet ring 42 is coupled to each of sidewalls 22 and 24 to define inlet openings 36 and includes an arcuate surface at inlet opening 36 to improve blower assembly 10 efficiency. Further, an air outlet opening 38 is defined, at least in part, by cutoff portion 30, sidewalls 22 and 24, and scroll wall 28. In the exemplary embodiment, airflow 100 is expelled from centrifugal blower assembly 10 through air outlet opening 38. In the exemplary embodiment, each component of housing 18 may be fabricated from any material that enables housing 18 to function as described herein, for example, without limitation, aluminum, steel, thermoplastics, fiber reinforced composite materials, or any combination thereof.
Further, in the exemplary embodiment, motor 16 of centrifugal blower assembly 10 is positioned in air inlet opening 36 and is coupled to housing 18 by a motor mounting assembly 200 that includes an end shield (not shown) and a plurality of mounting arms 204. Alternatively, motor 16 is coupled to blades 20 between sidewalls 22 and 24. Generally, motor 16 is positioned in any location that enables operation of assembly 10 as described herein.
In operation, fan impeller 12 rotates about axis of rotation 14 to draw air into housing 18 through air inlet opening 36. The amount of air moved by centrifugal blower assembly 10 increases as fan impeller 12 moves within housing 18 from cutoff point 32 towards air outlet opening 38. Scroll wall 28 is positioned progressively further away from fan impeller 12 in the direction of rotation of fan impeller 12 to accommodate the increasing volume of air due to the volute shape of housing 18. Fan impeller 12 generates high velocity airflow 100 that is exhausted from air outlet opening 38. Fan impeller 12 draws airflow 100 into centrifugal blower assembly 10 through air inlet opening 36 in the axial direction (referring to axis of rotation 14) and turns airflow 100 to a generally radial direction (generally perpendicular to axis of rotation 14).
FIG. 3 is a perspective view of impeller 12 and inlet rings 42 with housing 18 removed for clarity. FIG. 4 is a cross-sectional view of impeller 12 and one inlet ring 42. FIG. 5 is an enlarged cross-sectional view illustrating an exemplary notched blade 20 of impeller 12. In the exemplary embodiment, each blade 12 includes a leading edge 40, a trailing edge 42, and a pair of opposing axial ends 44. As shown in FIG. 5, the exemplary blade 20 also includes a twisted portion 46 extending from axial end 44 and coupled to an end ring 48 of impeller 12. End ring 48 is coupled to each blade 20 to support axial ends 44 in operation. An alternative blade type is illustrated in FIG. 6 that does not include twisted portion 46 and the axial end is coupled directly to the end ring, as described in further detail below.
In the exemplary embodiment, each blade 20 includes a notch 50 formed therein. Specifically, notch 50 is defined at the convergence of leading edge 40 and axial end 44 of blade 20. More specifically, notch 50 is defined by a notch axial surface 52 extending from leading edge 40 and by a notch radial surface 54 extending from blade axial end 44. As shown in FIG. 5, axial surface 52 is oriented perpendicular to axis 14 and radial surface 54 is oriented parallel to axis 14. Although notch 50 is shown as rectangular with surfaces 52 and 54 illustrated as being planar and oriented perpendicular to each other, notch 50 includes any shape that facilitates operation as described herein. For example, notch 50 may also include curved surfaces, surfaces oriented obliquely with respect to axis 14, or any combination thereof.
As best shown in FIG. 5, when blower assembly 10 is assembled and operational, inlet ring 42 is radially aligned with and extends axially into notch 50. That is, inlet ring 42 extends axially beyond end ring 48 and beyond axial end 44 of blades 20 toward interior space 34. As such, inlet ring 42 partially overlaps notch radial surface 54 in the axial direction. More specifically, inlet ring 42 includes a ring axial end 56 and a ring radially outer surface 58. Ring axial end 56 is positioned inward, toward interior space 34, of both blade axial end 44 and end ring 48.
Furthermore, ring axial end 56 and notch axial surface 52 define a first gap 60 therebetween. In the exemplary embodiment, first gap 60 extends a distance D1 within the range of approximately 0.2 inches (in.) and 0.5 in. More specifically, first gap 60 extends a distance D1 with the range of approximately 0.25 inches (in.) and 0.375 in. Generally, first gap 60 extends any distance D1 that facilitates operation of blower assembly 10 as described herein. Similarly, ring radially outer surface 58 and notch radial surface 54 define a second gap 62 therebetween. In the exemplary embodiment, second gap 62 extends a distance D2 within the range of approximately 0.2 inches (in.) and 0.5 in. More specifically, second gap 62 extends a distance D2 with the range of approximately 0.25 inches (in.) and 0.375 in. Generally, second gap 62 extends any distance D2 that facilitates operation of blower assembly 10 as described herein. In the exemplary embodiment, gaps 60 and 62 are substantially equal in size. In another embodiment, gaps 60 and 62 are different in size.
Including notch 50 on blades 20 allows for a longer blade length, which increases the overall operation area of the blades 20. Increasing the operational area increases the efficiency of the blades 20 because the close proximity of the inlet ring 42 to blades 20 reduces recirculation losses. Notch 50 creates a “seal” between impeller 12 and inlet ring 42 to reduce the amount of air entering through inlet 36 from leaking between impeller 12 and inlet ring 42. Moreover, the small size of the gap between end ring 48 and inlet ring 42 further reduces recirculation, which also increases the efficiency of blower assembly 10. Additionally, notch 50 creates clearance for manufacturing tolerances and for impeller displacement when blower assembly 10 is subjected to external shock to prevent impeller 12 from impacting inlet ring 42. As such, notch 50 enables a longer blade to reduce recirculation, while also allowing for potential impeller displacement.
FIG. 6 is an enlarged cross-sectional view illustrating an alternative embodiment of an impeller 112 for use in blower assembly 10. Impeller 112 is substantially similar to impeller 12 (shown in FIG. 5) in operation and composition, with the exception that blade 120 of impeller 112 does not include the twisted portion 46 of blade 20 and end ring 148 is a substantially flat disc rather than the roll crimped end ring 48 of impeller 12. As such, like components shown in FIG. 6, such as notch 50 and inlet ring 42, are labeled with the same reference numbers used in FIG. 5. Impeller 112 may be substituted for impeller 12 for use within blower assembly 10. Notch 50 on blade 120 provides the same advantages as describe above with respect to blade 20. Furthermore, blade 120 may be more efficient than blade 20 due to the increased operational length of blade 120 as a result of not having twisted portion 46, as blade 20 does.
FIG. 7 is an enlarged cross-sectional view illustrating another alternative configuration of impeller 12 and inlet ring 42. In the configuration shown in FIG. 7, axial end 56 of inlet ring 42 is still radially aligned with notch 50 of blade 20. However, axial end 56 of inlet ring 42 is axially spaced a distance from axial end 44 of blade 20 such that inlet ring 42 does not axially overlap with any portion of blade 20. Furthermore, axial end 56 of inlet ring 42 is also axially spaced a distance from an axial end surface 49 of end ring 48 to define a minimal axial gap 64 between inlet ring 42 and end ring 48 to allow for easier assembly. In such a configuration, even though inlet ring 42 does not overlap with blade 20, notch 50 allows for end ring 48, and therefore blades 20, to be positioned axially closer to inlet ring 42 to reduce recirculation and increase efficiency while preventing impeller 12 from impacting inlet ring 42, as described herein.
FIG. 8 is an enlarged cross-sectional view illustrating yet another alternative configuration of impeller 112 and inlet ring 42. The configuration of FIG. 8 illustrates a similar configuration as shown in FIG. 7 using impeller 112 rather than impeller 12. Specifically, axial end 56 of inlet ring 42 is still radially aligned with notch 50 of blade 120. However, axial end 56 of inlet ring 42 is axially spaced a distance from axial end 144 of blade 120 such that inlet ring 42 does not axially overlap with any portion of blade 120. Furthermore, axial end 56 of inlet ring 42 is also minimally axially spaced a distance from an axial end surface 149 of end ring 148 to define a small axial gap 164 between inlet ring 42 and end ring 148. In such a configuration, even though inlet ring 42 does not overlap with blade 120, notch 50 allows for end ring 148, and therefore blades 120, to be positioned axially closer to inlet ring 42 to reduce recirculation and increase efficiency, while preventing impeller 12 from impacting inlet ring 42, as described herein.
The apparatus, methods, and systems described herein provide a centrifugal blower having increased efficiency. More specifically, the impeller described herein includes a plurality of blades that each include a notch formed at the convergence of the blades leading edge and the blades axial end. The notch is radially aligned in the blower assembly with an inlet ring to reduce the distance between the inlet ring and the blades, as compared to known blower assemblies. In some embodiments, the inlet ring extends axially beyond an end ring of the impeller and into the notch on the blade such that the inlet ring axially overlaps with a portion of the blade. Including the notch on the blades reduces the distance between the axial end of the inlet ring and the blade to reduce recirculation losses and increase efficiency. The notches create a “seal” between the impeller and the inlet ring to reduce the amount of air from leaking between the impeller and the inlet ring and bypassing the impeller. Additionally, notches create clearance for manufacturing tolerances and for impeller displacement should the blower assembly be subjected to external shock to prevent the impeller from impacting the inlet ring. As such, the notches enable a longer blade to reduce recirculation, while also allowing for potential impeller displacement.
Exemplary embodiments of the centrifugal blower are described above in detail. The centrifugal blower and its components are not limited to the specific embodiments described herein, but rather, components of the systems may be utilized independently and separately from other components described herein. For example, the components may also be used in combination with other machine systems, methods, and apparatuses, and are not limited to practice with only the systems and apparatus as described herein. Rather, the exemplary embodiments can be implemented and utilized in connection with many other applications.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

What is claimed is:

1. A centrifugal blower assembly comprising:

a housing defining an interior space;

at least one inlet ring coupled to said housing and configured to define an inlet into the interior space; and

an impeller configured to rotate about an axis to channel an airflow through the inlet and within the interior space, wherein said impeller comprises a plurality of blades that each include a notch formed therein, wherein said notch is radially aligned with said at least one inlet ring.

2. The centrifugal blower assembly in accordance with claim 1, wherein said at least one inlet ring extends into said notch.

3. The centrifugal blower assembly in accordance with claim 1, wherein each blade of said plurality of blades comprises a leading edge and a blade axial end, said notch defined at a convergence of said leading edge and said blade axial end.

4. The centrifugal blower assembly in accordance with claim 1, wherein each blade of said plurality of blades comprises a leading edge and a blade axial end, said notch defined by a notch axial surface extending from said leading edge and a notch radial surface extending from said blade axial end.

5. The centrifugal blower assembly in accordance with claim 4, wherein said at least one inlet ring extends axially beyond said blade axial end.

6. The centrifugal blower assembly in accordance with claim 4, wherein said at least one inlet ring axially overlaps said notch radial surface.

7. The centrifugal blower assembly in accordance with claim 4, wherein said at least one inlet ring comprises a ring axial end, where a first gap is defined between said ring axial end and said notch axial surface.

8. The centrifugal blower assembly in accordance with claim 7, wherein said first gap is within a range of approximately 0.25 inches (in.) and 0.375 in.

9. The centrifugal blower assembly in accordance with claim 7, wherein said at least one inlet ring comprises a ring radially outer surface, where a second gap is defined between said ring radially outer surface and said notch radial surface.

10. The centrifugal blower assembly in accordance with claim 9, wherein said second gap is within a range of approximately 0.25 inches (in.) and 0.375 in.

11. The centrifugal blower assembly in accordance with claim 7, wherein said ring axial end is axially spaced from said blade axial end.

12. The centrifugal blower assembly in accordance with claim 1, wherein said impeller comprises an end ring coupled to said plurality of blades.

13. The centrifugal blower assembly in accordance with claim 12, wherein said inlet ring extends axially beyond said end ring.

14. The centrifugal blower assembly in accordance with claim 12, wherein said inlet ring is axially spaced from said end ring to define a gap therebetween.

15. A method of assembling a centrifugal blower assembly, said method comprising:

providing a housing that defines an interior space;

positioning an impeller within the housing such that the impeller is configured to rotate about an axis to channel an airflow within the interior space, wherein the impeller includes a plurality of blades that each include a notch formed therein; and

coupling an inlet ring to the housing to define an inlet into the interior space, wherein the inlet ring is radially aligned with each notch of the plurality of blades.

16. The method in accordance with claim 15, wherein coupling the inlet ring comprises coupling the inlet such that the inlet ring extends into each notch.

17. The method in accordance with claim 15, wherein coupling the inlet ring comprises coupling the inlet such that the inlet ring extends axially beyond an axial end of each blade and such that the inlet ring axially overlaps a radial surface of the notches.

18. The method in accordance with claim 15, wherein coupling the inlet ring comprises:

coupling the inlet ring to define a first gap between an axial end of the inlet ring and an axial surface of the notches; and

coupling the inlet ring to define a second gap between a radially outer surface of the inlet ring and a radial surface of the notches.

19. The method in accordance with claim 15, wherein coupling the inlet ring comprises coupling the inlet ring such that the inlet ring extends axially beyond an end ring of the impeller.

20. The method in accordance with claim 15, wherein coupling the inlet ring comprises coupling the inlet ring to define an axial gap between the inlet ring and an end ring of the impeller.