Patent Grant
11255348
The embodiments described herein relate generally to blower assemblies, and more particularly, to blower assemblies that reduce noise and increase efficiency in forced air or air circulating systems.
Many known commercial ventilation, heating, and air conditioning systems require air propulsion units. In addition to providing movement of air for such systems, air propulsion units may be used in combination with condenser units or to supplement other heat transfer operations. Some known air propulsion units are motor driven fans. These fans may be, for example, a plenum wheel driven by an electric motor.
At least some known blower assemblies include a plug fan with a plurality of circumferentially-spaced backward curved blades that are rotated by a motor to intake an airflow in an axial direction and exhaust the airflow in a radial direction. In such a configuration, the airflow exiting the fan may attach to the walls of the flow passage as soon as it exits the fan. As a result, an area of air recirculation may form which increases overall noise and also decreases the efficiency on the system.
At least some known blower assemblies include features on the fan or upstream of the fan to reduce recirculation. For example, at least some known fans include flow straighteners at the inlet of the fan. However, such flow straighteners can be expensive to manufacture and install. Furthermore, at least some known fans include specially designed blade profiles and features that are meant to reduce recirculation. However, such blade features may be difficult and expensive to manufacture.
In one aspect, a blower assembly having an axis of rotation is provided. The blower assembly includes a fan assembly configured to rotate about the axis and including a fan inlet ring that at least partially defines a fan inlet and a fan outlet. The blower assembly also includes a frame assembly coupled to the fan assembly and a recirculation damper coupled to the frame assembly. The recirculation damper and the fan inlet ring define an axial gap therebetween to reduce recirculation of an airflow discharged from the fan outlet.
In another aspect, a method of assembling a blower assembly having an axis of rotation is provided. The method includes coupling a fan assembly to a frame assembly. The fan assembly is configured to rotate about the axis and includes a fan inlet ring that at least partially defines a fan inlet and a fan outlet. The method also includes coupling a recirculation damper to an inlet plate of the frame assembly. The recirculation damper includes a radially inner portion, a radially outer portion, and a crown portion positioned therebetween. The crown portion being a portion of the recirculation damper positioned furthest from the inlet plate. The recirculation damper is coupled with respect to the fan inlet ring to define an axial gap between the crown portion and the fan inlet ring to reduce recirculation of an airflow discharged from the fan outlet.
In yet another aspect, a recirculation damper is provided. The recirculation damper is for use with a blower assembly having a frame assembly and a fan assembly including a fan inlet ring and an axis of rotation. The recirculation damper includes a radially inner portion configured to be coupled to a frame inlet ring of the frame assembly and a radially outer portion configured to be coupled to an inlet plate of the frame assembly. The recirculation damper also includes a crown portion positioned between the radially inner portion and the radially outer portion. The crown portion being a portion of the recirculation damper positioned furthest from the inlet plate. An axial gap is configured to be defined between the crown portion and the fan inlet ring to reduce recirculation of an airflow discharged from the fan outlet.
The present disclosure provides blower assemblies with improved structural designs that improve air flow downstream of the fan. Specifically, one blower assembly includes a recirculation damper that reduces recirculation and other downstream disturbances in the airflow. which results in increased efficiency. More specifically, the recirculation damper is positioned with respect to the inlet ring of the fan to define an axial gap therebetween that allows the airflow exiting the fan to attach to the surface of the recirculation damper and be guided downstream without forming eddies or vortices caused by recirculation. Such a reduction of recirculation results in efficiency increases and noise reduction of the blower assembly due to the ability to operate at lower torque requirements, thus increasing the efficiency, and also at lower speeds, thus reducing the noise levels.
Rear plate 30 and inlet ring 32 are coaxial or substantially coaxial and configured to rotate about a center axis 26. Blades 28 are attached to rear plate 30 and/or inlet ring 32 such that each blade 28 extends between rear plate 30 and inlet ring 32. In one embodiment, each blade 28 may be attached to rear plate 30 and/or inlet ring 32 via features formed in rear plate 30 and/or inlet ring 32 such as an opening, e.g., a groove or a slot, configured to restrict an amount of movement of blade 28 between rear plate 30 and inlet ring 32 while permitting blades 28 to operate as described herein. Blades 28 may be coupled to rear plate 30 and/or inlet ring 32 in any manner that permits fan 24 to operate as described herein. During rotation, blades 28 are configured to pull in air through inlet 36 along center axis 26 and eject the air radially outward through an outlet 40 located between adjacent blades 28. Specifically, inlet ring 32 includes an inlet end 42 that at least partially defines inlet 36 and an outlet end 44 that at least partially defines outlet 40.
In the exemplary embodiment, blower assembly 10 also includes a recirculation damper 46 coupled to frame assembly 12 such that recirculation damper 46 and inlet ring 32 define an axial gap 48 therebetween. As described here, gap 48 facilitates reducing recirculation of an airflow 50 discharged from outlet 40. Specifically, recirculation damper 46 is coupled to at least one of inlet plate 16 and inlet ring 34 of frame assembly 12 such that recirculation damper 46 circumscribes at least a portion of inlet ring 34. In one embodiment, recirculation damper 46 is formed integrally with one of inlet plate 16 or inlet ring 34.
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In the exemplary embodiment, axial gap 48 is defined between outlet end 44 of inlet ring 32 and crown portion 56 of recirculation damper 46. Furthermore, crown portion 56 of recirculation damper 46 defines a first diameter D1 and outlet end 44 of inlet ring 32 defines a second diameter D2 that is less than first diameter D1 such that crown portion 56 is positioned radially outward of outlet end 44. In the exemplary embodiment, axial gap 48 is within a range of between approximately 0.5 inches and approximately 6.0 inches. More specifically, axial gap 48 is within a range of between approximately 0.5 inches and approximately 2.0 inches. Generally, axial gap 48 is any size that facilities operation of blower assembly 10 as described herein.
During operation, air enters blower assembly 10 through central air inlet 36 and is deflected radially outward from central axis 26 toward blades 28. Blades 28 are configured to pull the air through inlet 36 into central chamber 38 of fan 24. The air passes through channels between blades 28 and is forced outward through outlet 40 due to the centrifugal force generated by rotating blades 28. In addition, in some known fans, the volume of airflow forced outward changes with respect to the speed of the fan's rotation.
As the airflow 50 exits outlet 40, recirculation damper 46 is shaped such that airflow 50 attaches to recirculation damper 46 to guide it out of fan 24. More specifically, airflow 50 forms a laminar boundary layer on crown portion 56 and radially outer portion 54 of recirculation damper 46. As such, recirculation damper 46 provides a structure to which airflow 50 can attach and, therefore reduces the formation of eddies and vortices caused by recirculation. As described herein, recirculation of the airflow exiting the fan can cause efficiency losses and also increase the noise level generated by the blower assembly. However, in the exemplary embodiment, recirculation damper 46 guides airflow 50 from outlet 40 along radially outer portion 54 and prevents or reduces recirculation of airflow 50 proximate inlet rings 32 and 34 and inlet plate 16. Such a reduction of recirculation results in efficiency increases and noise reduction of blower assembly 10. Specifically, the reduction in recirculation and turbulence enables fan 24 to operate at lower torque requirements, thus increasing the efficiency of fan 24. Similarly, the reduction in recirculation and turbulence enables fan 24 to operate at lower speeds, thus reducing the noise levels generated by fan 24.
The present disclosure provides blower assemblies with improved structural designs that improve air flow downstream of the fan. Specifically, one blower assembly includes a recirculation damper that reduces recirculation and other downstream disturbances in the airflow. which results in increased efficiency. More specifically, the recirculation damper is positioned with respect to the inlet ring of the fan to define an axial gap therebetween that allows the airflow exiting the fan to attach to the surface of the recirculation damper and be guided downstream without forming eddies or vortices caused by recirculation. Such a reduction of recirculation results in efficiency increases and noise reduction of the blower assembly due to the ability to operate at lower torque requirements, thus increasing the efficiency, and also at lower speeds, thus reducing the noise levels.
The embodiments described herein relate to a blower assembly and methods of assembling the same. More specifically, the embodiments relate to blower assemblies that includes a backward curved fan and recirculation damper that reduces or prevents airflow recirculation at the outlet of the fan to improve the efficiency and reduce the noise level of the blower assembly. More particularly, one embodiment relates to positioning the recirculation damper proximate an inlet ring of the fan to define an axial gap therebetween to reduce recirculation of the airflow discharged from the fan outlet. The methods and apparatus are not limited to the specific embodiments described herein, but rather, components of apparatus and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with a forward curved fan or blower assembly, and are not limited to practice with only the backward curved fan as described herein. In addition, the embodiment can be implemented and utilized in connection with many other HVAC applications.
Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, 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 also 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 language of the claims.
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