OUTLET SOUND ATTENUATING DEVICE

Description

CLAIM OF PRIORITY

This application claims priority to U.S. Provisional Application Ser. No. 63/803,054, filed May 9, 2025, and 63/726,774, filed Dec. 2, 2024, each of which are hereby incorporated by reference herein in their entirety.

BACKGROUND

Centrifugal fans are employed in a variety of different applications and systems, including commonly as plenum fans in air handling systems. Plenum centrifugal fans commonly draw air into an inlet cone axially and eject the air from the fan impeller radially toward the walls of a cubical or rectangular prism/cuboid shaped housing of the fan. The ejected air is then forced out of the outlet end of the fan. Plenum fans, including plenum centrifugal fans can incorporate sound damping mechanisms, including, e.g. sound damping materials in or lining the housing walls around the impeller and motor of such fans.

SUMMARY

Examples according to this disclosure are directed to systems and methods for attenuating fan sound. For example, a sound attenuation device can be arranged and configured to absorb and attenuate sound at/around/near the outlet end of a centrifugal fan. Examples according to this disclosure can include a toroidal sound attenuation device (TSAD) with sound wave propagation apertures and sound absorptive material. The TSAD is configured to be arranged downstream of a centrifugal fan impeller surrounding a portion of the fan motor.

An example according to this disclosure includes a sound attenuation device for a centrifugal fan. The sound attenuation device includes a toroidal housing and a sound absorptive material. The toroidal housing has a plurality of apertures in a radially outer surface. The sound absorptive material is arranged in the toroidal housing. The toroidal housing includes a central opening sized and shaped to receive at least a portion of a motor of the centrifugal fan.

In another example, a centrifugal fan includes a housing, an impeller, a motor, and a toroidal sound attenuation device. The housing has an air inlet and air outlet between which air is configured to flow through the fan. The impeller is arranged in the housing. The motor is operatively coupled to and configured to rotate the impeller. The toroidal sound attenuation device includes a toroidal housing in which a sound absorptive material is arranged and a radially outer surface including a plurality of apertures.

In another example, air handling system includes at least one centrifugal fan including a housing, an impeller, a motor, and a toroidal sound attenuation device. The housing has an air inlet and air outlet between which air is configured to flow. The impeller is arranged in the housing. The motor is operatively coupled to and configured to rotate the impeller. The toroidal sound attenuation device includes a toroidal housing in which a sound absorptive material is arranged and a radially outer surface including a plurality of apertures.

This overview is intended to provide an overview of subject matter in the present application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1A is an isometric view depicting an example centrifugal fan having a sound attenuation device according to this disclosure.

FIG. 1B is a section view depicting the example centrifugal fan of FIG. 1A.

FIGS. 2A-2D depict the example sound attenuation device of FIGS. 1A and 1B.

FIG. 3 schematically depicts an air handling system including a centrifugal fan having a sound attenuation device according to this disclosure.

DESCRIPTION

FIGS. 1A-1B depict example centrifugal fan 100 including housing 102 with air inlet 104 and air outlet 106 between which air is configured to flow through fan 100. FIG. 1A is an isometric view depicting example centrifugal fan 100 according to this disclosure. And FIG. 1B is a section view depicting centrifugal fan 100. Centrifugal fan 100 also includes impeller 108, motor 110, toroidal sound attenuation device (TSAD) 112, inlet cone (also referred to as inlet nozzle) 114, and outlet diffuser 116. Centrifugal fan 100 can be employed in a variety of applications and systems, including, for example, as a plenum fan in an air handling system.

Centrifugal fan 100 can include frame 118 connected to housing 102. Frame 118 can provide structural integrity and/or rigidity to housing 102 and can connect fan 100 to portions of a larger system or device, e.g. to a plenum of an air handling system.

Motor 110 is operatively connected to and configured to rotate impeller 108. Motor 110 can be connected to housing 102 and/or frame 118 via motor mount 120, which can include bushings 122 to, e.g., damp vibrations of motor 110. Impeller 108 is configured to draw air into fan 100 through inlet 104 via inlet cone 114. Impeller 108 ejects air out of fan 100 through outlet 106 via diffuser 116. In examples, impeller 108 is configured to draw air into housing 102 through inlet 104 and cone 114 axially and expel the air radially outward from the impeller.

Outlet diffuser 116 includes an annular diffuser that can be sized and shaped to turn air 123 expelled radially by/from impeller 108 to be exhausted from fan 100 generally axially via outlet 106. In examples, diffuser 116 includes outer diffuser surface 124 and inner diffuser surface 126. Outer diffuser surface 124 can be a curved surface configured to turn radially ejected air from impeller 108 axially. For example, outer diffuser surface 124 can include a parabolic surface with a radial distance from an axis of rotation of impeller 108 to the parabolic surface increasing from near the upstream end of the impeller to near air outlet 106 of housing 102. In examples including the example depicted in FIGS. 1A and 1B, outer diffuser surface 124 can include a curved surface including a curved portion extending from the upstream end of impeller 108 and a conical portion extending from the curved portion toward air outlet 106 of housing 102. In such an example, the radial distance from an axis of rotation of impeller 108 to the curved and conical portions of the curved surface increases from near the upstream end of the impeller to near air outlet 106 of housing 102.

Example centrifugal fan 100 includes toroidal sound attenuation device (TSAD) 112. TSAD 112 is arranged radially outward of motor 110 and radially inward of housing 102 downstream of impeller 108 in the direction of air flow through centrifugal fan 100. TSAD 112 is arranged such that the device surrounds a portion of motor 110. TSAD 112 includes toroidal housing 128 in which sound absorptive material 130 is arranged. Toroidal housing 128 of TSAD 112 includes apertures 132.

FIGS. 2A-2D depict example TSAD 112 in greater detail, including toroidal housing 128 having apertures 132 and in which sound absorptive material 130 is arranged. Apertures 132 are arranged in radially outer surface 200 of toroidal housing 128 of TSAD 112. Toroidal housing 128 defines/includes central opening 202, which can be sized, shaped, and configured to receive a portion of a motor of a fan, e.g. motor 110 of centrifugal fan 100 as depicted in FIGS. 1A and 1B.

Referring to FIGS. 1A-2D, TSAD 112 is configured to attenuate sound generated by centrifugal fan 100. TSAD 112 is advantageously arranged to surround a portion of motor 110 of centrifugal fan 100. In operation, centrifugal fan 100 generates noise, including noise from motor 110 and air flowing through passages of housing 102, e.g. inlet 104, outlet 106, nose cone 114 and diffuser 116. Some noise generated by centrifugal fan 100 can be absorbed by TSAD 112. For example, sound propagating in housing 102, e.g. sound waves may be transmitted near TSAD 112. Apertures 132 in toroidal housing 128 are advantageously arranged in radially outer surface 200 to allow some sound waves to propagate through apertures 132 and be absorbed by sound absorptive material 130 of TSAD 112.

TSAD 112 can be scaled for a variety of fan sizes. Toroidal housing 128 can be constructed from a variety of materials, including metals and metal alloys, as well as polymers. In examples, toroidal housing 128 is constructed from sheet aluminum, steel, or alloys thereof. In other examples, toroidal housing 128 is plastic injection molded.

The number, shape, and arrangement of apertures 132 in radially outer surface 200 of toroidal housing 128 of TSAD 112 (and other example sound attenuation devices according to this disclosure) can vary in different examples according to this disclosure. For example, apertures 132 can include thru holes, slots, and combinations of holes and slots.

A variety of sound absorptive materials 130 can be employed in TSAD 112 (and other example sound attenuation devices according to this disclosure). For example, sound absorptive material 130 can include a variety of porous sound absorptive materials. In examples, sound absorptive material 130 includes one or more of mineral wool, melamine foam, slag wool, and denim insulation. In examples, sound absorptive material 130 can be encapsulated in an outer shell/envelope, including a thin film polymer outer shell/envelope to shape the material and assist with packaging, as well as preventing portions of the material from breaking off and entering the air stream flowing through centrifugal fan 100.

In examples, TSAD 112 can be advantageously configured to absorb and attenuate outlet noise of centrifugal fan 100. TSAD 112 may be particularly effective in absorbing and attenuating noise generated by centrifugal fan 100 in the middle to high frequency range. In examples, TSAD 112 and other sound attenuation devices according to this disclosure can reduce sound power levels as much as 8 decibels (dB) in the middle to upper octave band center frequency range. For example, TABLE 1 below shows sound levels for a fan with and without a sound attenuation device according to this disclosure at a variety of center frequencies.

Centrifugal fan 100 and other fans including sound attenuation devices according to this disclosure can be employed in a variety of applications and systems, including, for example, as a plenum fan in an air handling system. FIG. 3 schematically depicts example air-handling system (AHS) 300 having a single centrifugal fan 302 housed in air-handling compartment 304 and including toroidal sound attenuation device (TSAD) 312 according to this disclosure. Example fan 302 also includes inlet cone 306, impeller 308, motor 310, and annular diffuser 317.

Air-handling compartment 304 of AHS 300 includes inlet plenum 314 prior to inlet cone 306 and discharge plenum 312. Within air-handling compartment 304 is situated fan 302, which can include a fan frame, and other components associated with the function of the fan (e.g. dampers, controls, settling means, and associated cabinetry). Impeller 308 can include a fan wheel (not shown) having at least one blade and commonly a plurality of fan blades.

As noted, air-handling compartment 304 is divided into discharge plenum 312 and inlet plenum 314. The combined discharge plenum 312 and inlet plenum 314 can be referred to and conceived as airway path 316. Centrifugal fan 302 may be situated in discharge plenum 312 (as shown), inlet plenum 314, or partially within inlet plenum 314 and partially within discharge plenum 312. The portion of airway path 316 in which fan 302 is positioned may be generically referred to as the “fan section,” which is demarcated by reference numeral 318 in FIG. 3. Filter banks 320 and/or cooling coils (not shown) may be-added to the system either upstream or downstream of fan 302.

Fan 302 includes example TSAD 313 according to this disclosure. TSAD 313 is arranged radially outward of motor 310 within air-handling compartment 304 downstream of impeller 308 in the direction of air flow through centrifugal fan 302. TSAD 313 is arranged such that the device surrounds a portion of motor 310. TSAD 313 includes toroidal housing 328 in which sound absorptive material is arranged. Toroidal housing 328 of TSAD 313 can also include a plurality of apertures arranged in the radially outer surface of toroidal housing 328. Toroidal housing 328 defines/includes a central aperture, which can be sized, shaped, and configured to receive a portion of motor 310 of centrifugal fan 302.

TSAD 313 is configured to attenuate sound generated by centrifugal fan 302. TSAD 313 is advantageously arranged to surround a portion of motor 310 of centrifugal fan 302. In operation, centrifugal fan 302 generates noise, including noise from motor 310 and air flowing through passages of air-handling compartment 304, e.g. cone 306 and diffuser 317. Some noise generated by centrifugal fan 302 can be absorbed by TSAD 313. For example, sound propagating in air-handling compartment 304, e.g. sound waves may be transmitted near TSAD 313. The apertures in toroidal housing 328 can be advantageously arranged in the radially outer surface to allow some sound waves to propagate through the apertures and be absorbed by sound absorptive material inside toroidal housing 328.

TSAD 313 can be scaled for a variety of fan sizes. Toroidal housing 328 can be constructed from a variety of materials, including metals and metal alloys, as well as polymers. In examples, toroidal housing 328 is constructed from sheet aluminum, steel, or alloys thereof. In other examples, toroidal housing 328 is plastic injection molded.

The number, shape, and arrangement of apertures in the radially outer surface of toroidal housing 328 of TSAD 313 (and other example sound attenuation devices according to this disclosure) can vary in different examples according to this disclosure. For example, the plurality of apertures in toroidal housing 328 can include thru holes, slots, and combinations of holes and slots.

A variety of sound absorptive materials can be employed in TSAD 313 (and other example sound attenuation devices according to this disclosure). For example, TSAD 313 can include a variety of porous sound absorptive materials. In examples, TSAD 313 includes one or more of mineral wool, melamine foam, slag wool, and denim insulation sound absorption material. In examples, sound absorptive material in TSAD 313 can be encapsulated in an outer shell/envelope, including a thin film polymer outer shell/envelope to shape the material and assist with packaging, as well as preventing portions of the material from breaking off and entering the air stream flowing through centrifugal fan 302.

In examples, TSAD 313 can be advantageously configured to absorb and attenuate outlet noise of centrifugal fan 302. TSAD 313 may be particularly effective in absorbing and attenuating noise generated by centrifugal fan 302 in the middle to high frequency range. In examples, TSAD 313 and other sound attenuation devices according to this disclosure can reduce sound power levels as much as 8 decibels (dB) in the middle to upper octave band center frequency range.

Although example AHS 300 includes a single centrifugal fan 302, other examples according to this disclosure can include AHS including an array of a plurality of fans, including centrifugal fans, each of which can include a toroidal sound attenuation device according to this disclosure. For example, an AHS can include a plurality of centrifugal fans arranged in an array of multiple rows and columns in an air-handling compartment including a plenum.

The above description includes references to the accompanying drawings, which form a part of the description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

Method examples described herein can be machine or computer-implemented at least in part Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, the code can be tangibly stored on one or more volatile or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.

Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules may be hardware, software, or firmware communicatively coupled to one or more processors in order to carry out the operations described herein. Modules may hardware modules, and as such modules may be considered tangible entities capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. In an example, the software may reside on a machine-readable medium. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations. Accordingly, the term hardware module is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein. Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using software; the general-purpose hardware processor may be configured as respective different modules at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time. Modules may also be software or firmware modules, which operate to perform the methodologies described herein.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

The present application provides for the following exemplary embodiments or examples, the numbering of which is not to be construed as designating levels of importance:

• • Example 1 provides a centrifugal fan comprising: a housing with an air inlet and air outlet between which air is configured to flow; an impeller arranged in the housing; a motor operatively coupled to and configured to rotate the impeller; and a toroidal sound attenuation device comprising: a toroidal housing in which a sound absorptive material is arranged; and a radially outer surface including a plurality of apertures.
  • Example 2 provides the fan of Example 1 and optionally wherein the impeller is configured to draw air into the housing through the air inlet axially and expel the air radially outward from the impeller.
  • Example 3 provides the fan of Example 1 and optionally wherein the motor is arranged downstream of the impeller in a direction of air flow.
  • Example 4 provides the fan of Example 1 and optionally wherein the toroidal sound attenuation device is arranged radially outward of the motor and radially inward of the housing downstream of the impeller in a direction of air flow.
  • Example 5 provides the fan of Example 1 and optionally wherein: the motor is arranged downstream of the impeller in a direction of air flow; and the toroidal sound attenuation device surrounds at least a portion of the motor.
  • Example 6 provides the fan of Example 1 and optionally wherein: the toroidal housing comprises a central opening sized and shaped to receive at least a portion of the motor; and the toroidal sound attenuation device surrounds the at least a portion of the motor.
  • Example 7 provides the fan of Example 1 and optionally wherein the plurality of apertures comprises a plurality of slots in the radially outer surface of the toroidal sound attenuation device.
  • Example 8 provides the fan of Example 1 and optionally and further comprising an annular diffuser configured to direct air expelled radially outward by the impeller axially out of the air outlet of the housing.
  • Example 9 provides the fan of Example 8 and optionally wherein the annular diffuser comprises a curved surface extending from an upstream end of the impeller in a direction of air flow toward the air outlet of the housing.
  • Example 10 provides the fan of Example 9 and optionally wherein: the curved surface of the annular diffuser comprises a curved portion extending from the upstream end of the impeller and a conical portion extending from the curved portion toward the air outlet of the housing; and a radial distance from an axis of rotation of the impeller to the curved and conical surfaces increases from near the upstream end of the impeller to near the air outlet of the housing.
  • Example 11 provides the fan of Example 9 and optionally wherein the curved surface of the annular diffuser comprises a parabolic surface; and a radial distance from an axis of rotation of the impeller to the parabolic surface increases from near the upstream end of the impeller to near the air outlet of the housing.
  • Example 12 provides the fan of Example 1 and optionally and further comprising an inlet nozzle connected to the air inlet of the housing.
  • Example 13 provides a sound attenuation device for a centrifugal fan, the sound attenuation device comprising: a toroidal housing with a plurality of apertures in a radially outer surface; and a sound absorptive material arranged in the toroidal housing, wherein the toroidal housing comprises a central opening sized and shaped to receive at least a portion of a motor of the centrifugal fan.
  • Example 14 provides the sound attenuation device of Example 13 and optionally wherein the toroidal housing is configured to be arranged to surround at least a portion of the motor.
  • Example 15 provides the sound attenuation device of Example 13 and optionally wherein the plurality of apertures comprises a plurality of slots in the radially outer surface of the toroidal housing.
  • Example 16 provides air handling system comprising: at least one centrifugal fan comprising: a housing with an air inlet and air outlet between which air is configured to flow; an impeller arranged in the housing; a motor operatively coupled to and configured to rotate the impeller; and a toroidal sound attenuation device comprising: a toroidal housing in which a sound absorptive material is arranged; and a radially outer surface including a plurality of apertures.
  • Example 17 provides the air handling system of Example 16 and optionally wherein the impeller is configured to draw air into the housing through the air inlet axially and expel the air radially outward from the impeller.
  • Example 18 provides the air handling system of Example 16 and optionally wherein the motor is arranged downstream of the impeller in a direction of air flow.
  • Example 19 provides the air handling system of Example 16 and optionally wherein the toroidal sound attenuation device is arranged radially outward of the motor and radially inward of the housing downstream of the impeller in a direction of air flow.
  • Example 20 provides the air handling system of Example 16 and optionally wherein: the motor is arranged downstream of the impeller in a direction of air flow; and the toroidal sound attenuation device surrounds at least a portion of the motor.
  • Example 21 provides the air handling system of Example 16 and optionally wherein: the toroidal housing comprises a central opening sized and shaped to receive at least a portion of the motor; and the toroidal sound attenuation device surrounds the at least a portion of the motor.
  • Example 22 provides the air handling system of Example 16 and optionally wherein the plurality of apertures comprises a plurality of slots in the radially outer surface of the toroidal sound attenuation device.
  • Example 23 provides the air handling system of Example 16 and optionally and further comprising an annular diffuser configured to direct air expelled radially outward by the impeller axially out of the air outlet of the housing.
  • Example 24 provides the air handling system of Example 23 and optionally wherein the annular diffuser comprises a curved surface extending from an upstream end of the impeller in a direction of air flow toward the air outlet of the housing.
  • Example 25 provides the air handling system of Example 24 and optionally wherein: the curved surface of the annular diffuser comprises a curved portion extending from the upstream end of the impeller and a conical portion extending from the curved portion toward the air outlet of the housing; and a radial distance from an axis of rotation of the impeller to the curved and conical surfaces increases from near the upstream end of the impeller to near the air outlet of the housing.
  • Example 26 provides the air handling system of Example 24 and optionally wherein the curved surface of the annular diffuser comprises a parabolic surface; and a radial distance from an axis of rotation of the impeller to the parabolic surface increases from near the upstream end of the impeller to near the air outlet of the housing.
  • Example 27 provides the air handling system of Example 16 and optionally and further comprising an inlet nozzle connected to the air inlet of the housing.

Various aspects of the disclosure have been described. These and other aspects are within the scope of the following claims.