Patent Application
20200063748
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.
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.
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.
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.
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).
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
As best shown in
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.
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.
