US20240110723A1

US20240110723A1 - Silencer for a roof exhaust

Info

Publication number: US20240110723A1
Application number: US17/957,760
Authority: US
Inventors: Mazen Victor ELDADA
Original assignee: Silentec Ltee
Current assignee: Silentec Ltee
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2024-04-04

Abstract

A silencer for a roof exhaust has a duct defining an inlet fluidly connected with the axial fan and an outlet for discharging air from the duct. The duct has peripheral walls forming an exterior of the duct, including: a bottom wall, a top wall, and first and second side walls spaced from each other and extending from the bottom wall to the top wall. A plurality of bent sheet metal wall sections fastened to each other form the bottom wall, the top wall and the first and second side walls, including first, second and third wall sections having first, second and third profiles that are shaped differently. Baffles are connected to the peripheral walls and define a passageway that fluidly connects the inlet to the outlet. An acoustic material for acoustically isolating the duct is disposed between the baffles and the peripheral walls.

Description

FIELD OF TECHNOLOGY

The present technology relates to silencers for roof exhausts.

BACKGROUND

Roof exhausts are often implemented for discharging air from the inside of a building, such as for air quality control or heat exchange purposes. For instance, some examples of roof exhausts include those for axial fans, centrifugal fans, induced draft fans, forced draft fans, and vacuum pumps amongst others. The prime mover of each roof exhaust can be mounted on the roof or disposed inside the building with the exhaust air ducted through the roof. Such exhausts often generate significant amounts of noise which can be disruptive to the surrounding environment. To address this, a silencer is sometimes installed to receive the air or more generally the gas discharged by a roof exhaust in order to attenuate the noise generated thereby. However, such silencers can be expensive and may not have a solid construction which can be problematic in high wind load conditions. In addition, the silencer is often difficult to maintain which can negatively the sound attenuating performance of the silencer, particularly in applications where the roof exhaust discharges aerosolized particles that can accumulate on the silencer.
Thus there is a desire for a silencer for a roof exhaust that addresses at least in part some of these drawbacks.

SUMMARY

It is an object of the present technology to improve on at least some of the inconveniences and drawbacks present in the prior art.
According to one aspect of the present technology, there is provided a silencer for a roof exhaust. The silencer comprises: a duct defining an inlet configured to be fluidly connected with the roof exhaust and an outlet for discharging air from the duct, the duct comprising a plurality of peripheral walls, that together form an exterior of the duct, the plurality of peripheral walls comprising: a bottom wall; a top wall opposite the bottom wall; and first and second side walls spaced from each other and extending from the bottom wall to the top wall, the duct comprising a plurality of bent sheet metal wall sections fastened to each other to form the bottom wall, the top wall and the first and second side walls, the plurality of bent sheet metal wall sections including: a plurality of first wall sections, each first wall section of the plurality of first wall sections having a first profile; a plurality of second wall sections, each second wall section of the plurality of second wall sections having a second profile; a plurality of third wall sections, each third wall section of the plurality of third wall sections having a third profile, the first, second and third profiles being shaped differently; a plurality of baffles connected to the peripheral walls, the baffles defining a passageway of the silencer that fluidly connects the inlet to the outlet; and an acoustic material for acoustically isolating the duct, at least part of the acoustic material being disposed between the baffles and the peripheral walls.
In some embodiments, the duct has a duct height measured between the bottom wall and the top wall; and in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, the duct is symmetric about an axis bisecting the duct height.
In some embodiments, the duct has a duct width measured between the first and second side walls; and in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, the duct is symmetric about an axis bisecting the duct width.
In some embodiments, in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, each of the first and second side walls is formed by two of the first wall sections fastened to each other.
In some embodiments, each first wall section of the plurality of first wall sections comprises: a first portion extending vertically along approximately half of a duct height measured between the bottom wall and the top wall, the first portion having a first end and a second end; a second portion extending horizontally and laterally inwardly from the first end; a third portion extending horizontally and laterally inwardly from the second end; and a fourth portion extending vertically from the second portion to form a U shape together with the first and second portions.
In some embodiments, the second portion is longer than the third portion.
In some embodiments, in the cross-section of the silencer taken along the plane, each of the first and second side walls is formed by the two of the first wall sections connected to each other by the third portions thereof.
In some embodiments, each first wall section of the plurality of first wall sections further comprises a fifth portion extending horizontally and laterally inwardly from the fourth portion.
In some embodiments, each first wall section of the plurality of first wall sections further comprises a sixth portion extending vertically from the third portion to form a U shape together with the first and third portions.
In some embodiments, in the cross-section of the silencer taken along the plane, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections.
In some embodiments, in the cross-section of the silencer taken along the plane, each of the bottom wall and the top wall is formed at least in part by the second portion of each first wall section of the pair of the first wall sections.
In some embodiments, in the cross-section of the silencer taken along the plane, in each of the bottom wall and the top wall: the one of the third wall sections is disposed centrally and between the pair of the second wall sections; and the pair of the second wall sections is disposed between the pair of the first wall sections.
In some embodiments, each second wall section of the plurality of second wall sections is generally C-shaped; each second wall section of the plurality of second wall sections has a central portion and two end portions extending from opposite ends of the central portion; and in the cross-section of the silencer taken along the plane, for each of the bottom wall and the top wall, the central portion of each second wall section is vertically aligned with the second portion of each first wall section.
In some embodiments, each second wall section of the plurality of second wall sections has two lip portions extending from respective ones of the end portions; and for each second wall section of the plurality of second wall sections, the lip portions are generally perpendicular to the end portions and extend toward a centerline of the second wall section bisecting a distance between the end portions.
In some embodiments, each third wall section of the plurality of third wall sections is generally step shaped; each third wall section of the plurality of third wall sections has a central elevated portion and two end portions extending from opposite ends of the central elevated portion; and in the cross-section of the silencer taken along the plane, for each of the bottom wall and the top wall, the central elevated portion of the one of the third wall sections is vertically aligned with: (i) the central portion of each second wall section, and (ii) the second portion of each first wall section.
In some embodiments, each third wall section of the plurality of third wall sections has two lip portions extending from respective ones of the end portions of the third wall section; and for each third wall section of the plurality of third wall sections, the lip portions are generally perpendicular to the end portions of the third wall section and extend away from a centerline of the third wall section bisecting a distance between the end portions of the third wall section.
In some embodiments, each baffle of the plurality of baffles is perforated.
In some embodiments, each baffle of the plurality of baffles comprises a plurality of baffle panels that are fastened to each other; and each baffle panel of the plurality of baffle panels is a piece of bent sheet metal.
In some embodiments, the plurality of baffles comprises: a first side baffle connected to the first side wall, a first part of the acoustic material being disposed between the first side baffle and the first side wall; a second side baffle connected to the second side wall, a second part of the acoustic material being disposed between the second side baffle and the second side wall; at least one top baffle connected to the top wall, a third part of the acoustic material being disposed between the at least one top baffle and the top wall; and at least one bottom baffle connected to the bottom wall, a fourth path of the acoustic material being disposed between the at least one bottom baffle and the bottom wall.
In some embodiments, the silencer further comprises a deflector pod extending between the bottom wall and the top wall, the deflector pod comprising: a third side baffle of the plurality of baffles connected to the bottom wall and the top wall, a first sub-passage being defined between the first side baffle and the third side baffle; and a fourth side baffle of the plurality of baffles connected to the bottom wall and the top wall, a second sub-passage between the second side baffle and the fourth side baffle, a fifth part of the acoustic material being disposed between the third side baffle and fourth side baffle of the deflector pod.
In some embodiments, in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and traversing the deflector pod, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections; each third wall section of the plurality of third wall sections is generally step shaped; each third wall section of the plurality of third wall sections has a central elevated portion and two end portions extending from opposite ends of the central elevated portion; the third side baffle is fastened to a first end portion of the two end portions; and the fourth side baffle is fastened to a second end portion of the two end portions.
In some embodiments, the silencer further comprises a fiber glass membrane disposed between the baffles and the acoustic material.
In some embodiments, the silencer further comprises a plurality of adjustable legs connected to the duct, a height of each adjustable leg of the plurality of adjustable legs being adjustable to selectively set a distance between the bottom wall and a roof on which the roof exhaust is mounted.
In some embodiments, in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections; in each of the bottom wall and the top wall: the third wall section is disposed centrally and between the pair of the second wall sections; and the pair of the second wall sections is disposed between the pair of the first wall sections; each first wall section of the plurality of first wall sections comprises: a first portion extending vertically along approximately half of a duct height measured between the bottom wall and the top wall, the first portion having a first end and a second end; a second portion extending horizontally and laterally inwardly from the first end, the second portion forming in part an exterior surface of a corresponding one of the bottom wall and the top wall; a third portion extending horizontally and laterally inwardly from the second end; a fourth portion extending vertically from the second portion to form a U shape together with the first and second portions; and a fifth portion extending horizontally and laterally inwardly from the fourth portion; each second wall section of the plurality of second wall sections is generally C-shaped and comprises: a central portion; two first end portions extending from opposite ends of the central portion; and two first lip portions extending from respective ones of the first end portions, the first lip portions being generally perpendicular to the first end portions and extending toward a centerline of the second wall section bisecting a distance between the first end portions; each third wall section of the plurality of third wall sections is generally step shaped and comprises: a central elevated portion; two second end portions extending from opposite ends of the central elevated portion; two second lip portions extending from respective ones of the second end portions, the second lip portions being generally perpendicular to the second end portions and extending away from a centerline of the third wall section bisecting a distance between the second end portions; in the cross-section of the silencer taken along the plane, in each of the bottom wall and the top wall: a laterally outermost one of the first lip portions of each of the second wall sections is disposed above or under the fifth portion of an adjacent one of the first wall sections; a laterally innermost one of the first lip portion of each of the second wall sections is disposed above or under a corresponding one of the second lip portions of the one of the third wall sections.
In some embodiments, in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet: each of the first and second side walls is formed by two of the first wall sections; each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections; the plurality of baffles comprises: a first side baffle connected to the first side wall, a first part of the acoustic material being disposed between the first side baffle and the first side wall; a second side baffle connected to the second side wall, a second part of the acoustic material being disposed between the second side baffle and the second side wall; at least one top baffle connected to the top wall, a third part of the acoustic material being disposed between the at least one top baffle and the top wall; and at least one bottom baffle connected to the bottom wall, a fourth path of the acoustic material being disposed between the at least one bottom baffle and the bottom wall; the silencer further comprises a deflector pod extending between the bottom wall and the top wall, the deflector pod comprising: a third side baffle of the plurality of baffles connected to the bottom wall and the top wall, a first sub-passage being defined between the first side baffle and the third side baffle; a fourth side baffle of the plurality of baffles connected to the bottom wall and the top wall, a second sub-passage between the second side baffle and the fourth side baffle, a fifth part of the acoustic material being disposed between the third side baffle and fourth side baffle of the deflector pod.
In some embodiments, the duct has a first end and a second end; the bottom wall, the top wall and the first and second side walls extend from the first end to the second end; the inlet is defined by the bottom wall; the plurality of peripheral walls further comprises a first end wall closing off the first end of the duct; and the outlet is defined at the second end of the duct.
In some embodiments, the silencer further comprises a deflector pod disposed laterally between the first and second side walls, the deflector pod defining in part first and second sub-passages between the deflector pod and the first and second side walls respectively, the deflector pod being spaced from the first end of the duct, the inlet being disposed between the first end of the duct and an end of the deflector pod.
According to another aspect of the present technology, there is provided a silencer for a roof exhaust, comprising: a duct defining an inlet configured to be fluidly connected with the roof exhaust and an outlet for discharging air from the duct, the duct comprising a plurality of peripheral walls that together form an exterior of the duct, the plurality of peripheral walls comprising: a bottom wall defining the inlet; a top wall opposite the bottom wall; first and second side walls spaced from each other and extending from the bottom wall to the top wall, the bottom wall, the top wall and the first and second side walls extending from a first end of the duct to a second end of the duct; and a first end wall defining the first end of the duct, a plurality of baffles connected to the peripheral walls, the baffles defining a passageway of the silencer that fluidly connects the inlet to the outlet; and an acoustic material for acoustically isolating the duct, at least part of the acoustic material being disposed between the baffles and the peripheral walls.
In some embodiments, an exhaust assembly comprises a roof exhaust configured to be mounted to a roof, the roof exhaust comprising a conduit for discharging air therefrom, the conduit defining a central axis; and the silencer mounted to the roof exhaust, wherein the central axis extends through the bottom wall of the duct.
Embodiments of the present technology each have at least one of the above-mentioned objects and/or aspects, but do not necessarily have all of them. It should be understood that some aspects of the present technology that have resulted from attempting to attain the above-mentioned objects may not satisfy these objects and/or may satisfy other objects not specifically recited herein.
Additional and/or alternative features, aspects and advantages of embodiments of the present technology will become apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present technology, as well as other aspects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where:

FIG. 1 is a left side elevation view of a roof exhaust equipped with a silencer according to an embodiment of the present technology;

FIG. 2 is a front elevation view of the roof exhaust and the silencer of FIG. 1 ;

FIG. 3 is a cross-sectional view of part of the silencer of FIG. 1 taken along line 3-3 in FIG. 1 ;

FIG. 4 is a cross-sectional view of part of the silencer of FIG. 1 taken along line 4-4 in FIG. 2 ;

FIG. 5 is a front elevation view of one of a plurality of first wall sections of a duct of the silencer of FIG. 1 ;

FIG. 6 is a front elevation view of one of a plurality of second wall sections of the duct of the silencer of FIG. 1 ;

FIG. 7 is a front elevation view of one of a plurality of third wall sections of the duct of the silencer of FIG. 1 ;

FIG. 8 is a right side elevation view of two baffle panels of a left side baffle of the silencer of FIG. 1 ;

FIG. 9 is a cross-sectional view of the two baffle panels of FIG. 8 taken along line 9-9 in FIG. 8 ; and

FIG. 10 is a left side elevation view a roof exhaust equipped with a silencer according to an alternative embodiment.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a silencer 10 according to an embodiment of the present technology. The silencer 10 is configured to be fluidly connected to a roof exhaust 200 in order to attenuate the noise generated thereby. Notably, during operation, the roof exhaust 200 can generate a significant amount of noise which can be disruptive to the surrounding environment. As can be seen, the roof exhaust 200 is provided on a roof 202 of a building and is operable to discharge air from the building (e.g., originating from an industrial process, machinery inside the building or to collaborate in cooling the building). In this embodiment, the roof exhaust 200 is a roof-mounted axial fan. The axial fan 200 includes a cylindrical conduit 204 and an impeller (not shown) contained in the conduit 204. The impeller is rotatable about a central axis 208 of the conduit 204 extending generally vertically. It is to be understood that the axial fan 200 is one example of a roof exhaust. In other embodiments, the roof exhaust could be a different type of exhaust, such as a centrifugal fan, an induced draft fan, a forced draft fan, and a vacuum pump amongst others. For instance, in some embodiments, the roof exhaust 200 may not include an impeller (e.g., the element forcing the air through the conduit 204 could be located inside the building).
The silencer 10 includes a duct 12 defining an internal space within which internal components of the silencer 10 are disposed. The duct 12 extends in a longitudinal direction from a first end 14 to a second end 16, defining a length of the duct 12 therebetween. The silencer 10 has respective end frames 17 connected to the duct 12 at each end 14, 16. As shown in FIG. 2 , each end frame 17 defines openings 19 along a top portion thereof configured to receive a hook in order to lift the silencer 10 during installation thereof. The duct 12 defines an inlet 18 that is fluidly connected to the axial fan 200 to receive air therefrom and an outlet 20 for discharging air from the duct 12. As shown in FIG. 3 , the silencer 10 also has a plurality of baffles 40 disposed within the duct 12. The baffles 40 are connected to the duct 12 and define a passageway 25 of the silencer 10 that communicates the inlet 18 to the outlet 20. The silencer 10 also includes an acoustic material 35 that acoustically isolates the duct 12. The acoustic material 35 also provides some thermal insulation and therefore can be said to thermo-acoustically insulate the duct 12. In addition, the acoustic material 35 provides an acoustic plenum effect and dissipative acoustic baffle silencer attenuation. In this embodiment, the acoustic material 35 is a layered composite acoustic material. For example, the acoustic material 35 may be fiberglass, rock wool or polyurethane foam that may be combined with tuned membranes made of fiberglass fabric, plastic film or metal foil. In this example, the acoustic material 35 is fibrous mineral wool. Other suitable types of acoustic materials are also contemplated. As will be described in more detail below, part of the acoustic material 35 is disposed between the baffles 40 and the duct 12. Furthermore, an optional tuned fiber glass membrane 37 (FIG. 9 ) is disposed between the baffles 40 and the acoustic material 35.
In this embodiment, the silencer 10 also has a plurality of adjustable legs 45 connected to the duct 12. The height of the adjustable legs 45 is adjustable to selectively set a distance between the duct 12 and the roof 202. The height of the adjustable legs 45 could be fixed in other embodiments. Bracing members (not shown) are also provided to brace the adjustable legs 45.
Furthermore, as shown in FIG. 1 , in this embodiment, the silencer 10 includes two modules 302, 304 that are connected to each other to form the silencer 10. The first module 302 defines the inlet 18 and therefore may be referred to as the inlet module. The inlet module 302 forms an acoustic plenum therein which serves to attenuate sound as well as to modify air flow as needed, such as diffusion, velocity reduction and direction change. Conversely, the second module 304 defines the outlet 20 and therefore may be referred to as the outlet module. The inlet and outlet modules 302, 304 are fastened to each other to form the continuous duct 12. The inlet module 302 and the outlet module 304 have respective connecting frames 21, 23 opposite the end frames 17 for connecting the inlet module 302 to the outlet module 304. Alternatively, in some embodiments, the connecting frames 21, 23 could be a single frame and the inlet and outlet modules 302, 304 could be integrally connected to each other, namely being constructed from peripheral external walls made of long sheet metal pieces (shown in FIGS. 5 to 7 ) each spanning from the first end 14 to the second end 16 as a single piece. The connecting frames 21, 23 may also defines openings (not shown) for hooking onto the frames 21, 23 to lift the inlet and outlet modules 302, 304 during installation. The separation of the silencer 10 into the inlet and outlet modules 302, 304 may facilitate transport and installation of the silencer 10.
With reference to FIGS. 1 to 3 , the duct 12 has a plurality of peripheral walls that together form an exterior of the duct 12 (i.e., its exterior envelope). In particular, the peripheral walls include a bottom wall 22, a top wall 24 opposite the bottom wall 22, left and right side walls 26 extending from the bottom wall 22 to the top wall 24, and an end wall 28. The bottom wall 22, the top wall 24, and the left and right side walls 26 extend from the first end 14 to the second end 16 of the duct 12. A height of the duct 12 is measured between the bottom wall 22 and the top wall 24, while a width of the duct 12 is measured between the left and right side walls 26. The end wall 28 is generally normal to the bottom wall 22, the top wall 24 and the left and right side walls 26. The end wall 28 also defines the first end 14 of the duct 12 and closes off the first end 14 (i.e., air flow is not possible through the first end 14). In this embodiment, the second end 16 is not closed off by a peripheral wall. Rather, the second end 16 defines the outlet 20 and is open to allow the flow of air to be discharged from the duct 12. It is contemplated that the second end 16 could be open but provided with a louver to impede entry of unwanted elements into the silencer 10.
As best shown in FIG. 4 , in this embodiment, the bottom wall 22 and the associated baffle 40 define a circular opening 23 corresponding to the inlet 18 of the duct 12. As can be seen in FIGS. 1 and 2 , the axial fan 200 is disposed underneath the duct 12 to be in communication with the opening 23. As such, the fan axis 208 extends through the opening 23 and through the top wall 24. A conduit 210 (FIGS. 1, 2 ) of the silencer 10 is disposed partly inside of the duct 12 and extends downward therefrom through the bottom wall 22 and is connected to the conduit 204 of the axial fan 200. As will be appreciated, the position of the axial fan 200 underneath the duct 12 and the communication therebetween such that a vertical air flow from the axial fan 200 transitions to a horizontal air flow in the passageway 25 allows the assembly of the axial fan 200 and the silencer 10 to be relatively compact.
As shown in FIG. 3 , in this embodiment, the peripheral walls of the duct 12 are configured such that, in a cross-section of the silencer 10 taken along a plane PN (FIG. 1 ) that is normal to the bottom wall 22, top wall 24 and side walls 26 and spaced from the inlet 18, the duct 12 is symmetric about an axis AH bisecting the height of the duct 12. Furthermore, in this embodiment, the peripheral walls of the duct 12 are configured such that, in a cross-section of the silencer 10 taken along a plane that is normal to the bottom wall 22, top wall 24 and side walls 26 and spaced from the inlet 18, the duct 12 is symmetric about an axis AV (FIG. 3 ) bisecting the width of the duct 12.
The construction of the peripheral walls will be described in greater detail further below.
As shown in FIGS. 3 and 4 , in this embodiment, a deflector pod 60, which may also be referred to as an “acoustic splitter” or “acoustic baffle” with air flowing on both sides, is disposed within the duct 12 and, in this embodiment, divides the passageway 25 into two sub-passages 27 on either side of the deflector pod 60. In use, the deflector pod 60 diverts the air flow within the silencer 10 into the two sub-passages 27 and plays a role in noise attenuation. The deflector pod 60 extends vertically between the bottom wall 22 and the top wall 24 and longitudinally from its leading end 62 that may be referred to as ‘bull nose’ to its trailing end 64 that may be referred to as ‘fishtail’ often shaped aerodynamically with diminishing thickness. The deflector pod 60 includes two of the baffles 40, namely left and right deflector side baffles 40D, which are connected to the bottom and top walls 22, 24 and are laterally spaced from each other. Part of the acoustic material 35 of the silencer 10 is disposed between the two deflector side baffles 40D. The deflector pod 60 also has a curved end cap 66 at the leading end 62 and connected to the two deflector side baffles 40D. As shown in FIG. 4 , the inlet 18 is disposed between the first end 14 of the duct 12 and the leading end 62 of the deflector pod 60.
In this embodiment, the deflector pod 60 forms part of the outlet module 304.
Notably, as shown in FIG. 4 , the outlet module 304 does not extend into the part of the duct 12 defined by the inlet module 302.
With continued reference to FIGS. 3 and 4 , in this embodiment, the baffles 40 also include left and right side baffles 40L, 40R, top and bottom baffles 40T, 40B, and an end baffle 40E. The left and right side baffles 40L, 40R and top and bottom baffles 40T, 40B extend generally parallel to the left and right side walls 26 and top and bottom walls 24, 22 respectively. In this embodiment, two top baffles 40T and two bottom baffles 40B are separated by the deflector pod 60. The end baffle 40E extends generally parallel to the end wall 28. As such, the passageway 25 is surrounded by the baffles 40 and thus by the acoustic material 35 disposed between the baffles 40 and the peripheral walls.
As shown for the left side baffle 40L in FIGS. 8 and 9 , in this embodiment, each of the baffles 40 includes a plurality of baffle panels 50 (only two of which are shown in FIGS. 8 and 9 for simplicity) that are fastened to each other. Each baffle panel 50 is a piece of bent sheet metal and has an outer surface 52 and an inner surface 54. A thickness of the piece of bent sheet metal is defined between the outer and inner surfaces 52, 54. In use, the inner surface 54 faces the acoustic material 35 disposed between the baffle 40 and the corresponding one of the peripheral walls. The baffle panels 50 have two opposite bent end portions 58 and a central portion 59 extending between the two bent end portions 58. The bent end portions 58 are generally perpendicular to the central portion 59. The adjacent bent end portions 58 of two of the baffle panels 50 that are disposed side-by-side are fastened to each other via fasteners 70. As can be seen in FIG. 8 , in this embodiment, the central portion 59 of each baffle panel 50 defines a plurality of perforations 56 such that, in use, sound can traverse the thickness of the baffle panel 50 to reach the acoustic material 35 to be dampened thereby.
As shown in FIG. 9 , the fiber glass membrane 37 (illustrated in dashed lines) is disposed against the inner surface 54 of the baffle panels 50 such that, in use, a piece of fiber glass membrane 37 is disposed between each baffle panel 50 and part of the acoustic material 35. The fiber glass membrane 37, when properly tuned and positioned, may provide further acoustic attenuation to the silencer 10, in addition to protecting the acoustic fibers against erosion and contamination from airborne particles.
The right side baffle 40R and the end baffle 40E (i.e., the other upstanding baffles 40) are configured in the same manner as described above with respect to the left side baffle 40L. The top and bottom baffles 40T, 40B are configured in a similar manner except that the baffle panels 50 thereof are secured end-to-end rather than side-by-side. The configuration of the top and bottom baffles 40T, 40B will therefore not be described in detail herein.
With reference now to FIGS. 3 and 5 to 7 , in this embodiment, the duct 12 includes a plurality of bent sheet metal wall sections that are fastened to each other to form the peripheral walls. It is to be understood that the spacing between the bent sheet metal wall sections shown in FIG. 3 has been exaggerated for clarity; in practice, the fastening of the bent sheet metal wall sections closes such spacings and seals them to prevent the leaking of sound, air, vapor and/or condensation therethrough. The bent sheet metal wall sections include three different types of sheet metal wall sections, namely first wall sections 30, second wall sections 32 and third wall sections 34. The wall sections 30, 32, 34 have respective profiles that are shaped differently from each other. In other words, the duct 12 can be assembled by fastening various ones of the first, second and third wall sections 30, 32, 34 together. As will be appreciated, by limiting the variety of bent sheet metal wall sections needed to assemble the duct 12, manufacturing of the silencer 10 can be simplified and associated production costs minimized.
As can be seen in FIG. 3 , in this embodiment, in a cross-section of the silencer 10 taken along the plane PN, each of the left and side walls 26 is formed by two of the first wall sections 30 that are fastened to each other. In particular, one of the first wall sections 30 is disposed vertically above another one of the first wall sections 30. The two first wall sections are oriented such that one is the mirror image of the other about the axis AH.
An exemplary one of the first wall sections 30 will now be described with reference to FIG. 5 . The same description applies to the other first wall sections 30. The first wall section 30 has a main vertical portion 72 that extends vertically along approximately half of the height of the duct 12. The main vertical portion 72 has an outer surface 74 that faces laterally outwardly. As shown in FIG. 3 , in the cross-section taken along the plane PN, the outer surfaces 74 of the two first wall sections 30 of the left or right side walls 26 form the exterior surface of that side wall 26. A transversal portion 76 of the first wall section 30 extends horizontally and laterally inwardly from an end of the main vertical portion 72. The transversal portion 76 has an outer surface 78 and forms part of the bottom wall 22 or the top wall 24 of the duct 12. A vertical portion 84 extends vertically from the transversal portion 76 to form a U shape together with the main vertical portion 72 and the transversal portion 76. The vertical portion 84 is thus parallel to the main vertical portion 72. A lip portion 86 extends horizontally and laterally inwardly from the vertical portion 84. The lip portion 86 defines an end of the piece of sheet metal forming the first wall section 30.
The first wall section 30 also has a connecting portion 80 that extends horizontally and laterally inwardly from an opposite end of the main vertical portion 72 (i.e., an end opposite the transversal portion 76). The connecting portion 80 is thus parallel to the transversal portion 76. The transversal portion 76 is longer than the connecting portion 80. The two first wall sections 30 of the left or right side walls 26 are fastened to each other at their respective connecting portions 80. In particular, the connecting portions 80 of the two first wall sections 30 abut each other and are fastened to each other by fasteners (not shown), such as rivets or bolts for example. A lip portion 82 extends vertically from the connecting portion 80 to form a U shape together with the main vertical portion 72 and the connecting portion 80.
An exemplary one of the second wall sections 32 will now be described with reference to FIG. 6 . The same description applies to the other second wall sections 32. As can be seen, the profile of the second wall section 32 is generally C-shaped in the cross-section taken along the plane PN. In particular, the second wall section 32 has a central portion 88 and two end portions 90 that extend from opposite ends of the central portion 88. The central portion 88 has an outer surface 102 which, in use, forms part of an exterior surface of a corresponding one of the bottom wall 22 and top wall 24. The end portions 90 are generally perpendicular to the central portion 88. Respective lip portions 92 extend laterally from the end portions 90 towards a centerline 91 of the profile of the second wall section 32 that bisects the lateral distance between the two end portions 90. As can be seen, the central portion 88 and the two end portions 90 form a recess 93 that, in use, is filled with the acoustic material 35.
An exemplary one of the third wall sections 34 will now be described with reference to FIG. 7 . The same description applies to the other third wall sections 34. As can be seen, the profile of the third wall section 34 is generally step shaped in the cross-section taken along the plane PN. More specifically, the third wall section 34 has a central elevated portion 94 and two end portions 96 that extend from opposite ends of the central elevated portion 94. The two end portions 96 are generally perpendicular to the central elevated portion 94 and form a recess 95 together therewith. As shown in FIG. 3 , in use, each deflector side baffle 40D is fastened to a respective one of the end portions 96. Respective lip portions 98 extend laterally from the end portions 96 away from a centerline 99 of the profile of the third wall section 34 that bisects the lateral distance between the two end portions 96. As can be seen, the central elevated portion 94 and the two end portions 96 form a recess 95 that, in use, is filled with the acoustic material 35.
Returning now to FIG. 3 , the construction of the bottom wall 22 and the top wall 24 will be described in detail. In this embodiment, the bottom wall 22 and the top wall 24 are mirror images of each other about the axis A11 and therefore only the top wall 24 will be described in detail herein. As can be seen, in the cross-section taken along the plane PN, the top wall 24 is formed by a pair of the first wall sections 30 forming the side walls 26, a pair of the second wall sections 32 and a single one of the third wall sections 30. In particular, along the top wall 24, the third wall section 34 is disposed centrally such that the axis AV extends through the central elevated portion 94 thereof. The third wall section 34 is disposed laterally between the pair of second wall sections 32. The two second wall sections 32 are disposed laterally between the pair of first wall sections 30. In other words, the first wall sections 30 are positioned laterally outwardly of the second wall sections 32. Moreover, as shown in FIG. 3 , in the cross-section taken along the plane PN, the pair of first wall sections forming the top wall 24 correspond to the same first wall sections 30 that form part of the left and right side walls 26. As such, each first wall section 30 forms part of one of the side walls 26 and part of the top wall 24.
Along the top wall 24, the profiles of the wall sections 30, 32, 34 are complementary to each other. In particular, the profiles of the wall sections 30, 32, 34 allow parts of the wall sections 30, 32, 34 to be nested with each other. For instance, each second wall section 32 is received in a recess formed between the third wall section 34 and one of the first wall sections 30. For instance, for each second wall section 32, a corner formed by one of the end portions 90 and a corresponding lip portion 92 is received by a corner formed by the vertical portion 84 and the lip portion 86 of one of the first wall sections 30. The other corner of each second wall section 32 formed by the other end portion 90 and lip portion 92 is received by a corner formed by an adjacent end portion 96 and corresponding lip portion 98 of the third wall section 34. This nested configuration of the wall sections 30, 32, 34 can help rigidify the top wall 24 without incurring high production costs. As such, in this embodiment, a laterally outermost one of the lip portions 92 of each second wall section 32 is laterally aligned with and disposed above (or under for the bottom wall 22) the lip portion 86 of the adjacent first wall section 86. Notably, the lip portions 86, 92 of the first and second wall sections 30, 32 are fastened to each other by mechanical fasteners (e.g., rivets, bolts, etc.). Similarly, a laterally innermost one of the lip portions 92 of each second wall section 32 is laterally aligned with and disposed above (or under for the bottom wall 22) the lip portion 98 of the third wall section 30. The lip portions 92, 98 of the second and third wall sections 32, 34 are also fastened to each other by mechanical fasteners.
As can be seen, the central elevated portion 94 of the third wall section 34, the central portions 88 of the second wall sections 32 and the transversal portion 76 of the first wall sections 30 are vertically aligned with each other. As such, the outer surfaces 78 of the transversal portions 76 of the two first wall sections 30, the outer surfaces 102 of the two central portions 88 of the second wall sections 32 and the outer surface 104 of the central elevated portion 94 of the third wall section 34 are flush with each other to form an exterior surface of the top wall 24.
Although the silencer 10 has been described and illustrated above as extending generally horizontally, it is contemplated that the silencer 10 could be disposed at an angle as shown in FIG. 10 which illustrates an alternative embodiment of the silencer 10. As can be seen, in this alternative embodiment, both the inlet module 302 and the outlet module 304 are disposed at an acute angle relative to a horizontal axis. It is contemplated that, in alternative embodiments, only the outlet module 304 could be disposed at an angle relative to the horizontal axis (i.e., the inlet module 302 extends parallel to the horizontal axis). In yet other alternative embodiments, two outlet modules 304 could be connected to and extend from opposite sides of a single inlet module 302. The two outlet modules 304 could extend horizontally or at angle relative to the inlet module 302.
Furthermore, it is contemplated that, in some embodiments, the outlet 20 could be defined on a top side of the outlet module 304. Moreover, in some cases, two outlet modules 304 could be disposed atop each other, with their respective outlets 20 defined on their top sides. In such cases, the silencer 10 could be L-shaped.
It is also contemplated that, in other embodiments, the inlet and outlet modules 302, 304 may be integrally connected to each other. In other words, the inlet and outlet modules 302, 304 may not be separately produced and secured to each other but rather could be produced as a single continuous component.
As will be appreciated from the above, the silencer 10 can be produced with a limited variety of bent sheet wall sections available. In particular, the duct 12 is made by assembling only three different types of bent sheet wall sections 30, 32, 34. Moreover, the manner in which the bent sheet walls sections 30, 32, 34 are connected to each other provides a rigid and resistant duct 12. Limiting the variety of components that have to be manufactured and stored to produce the silencer 10 is helpful to limit the costs of producing the silencer 10, including for example the costs associated with maintaining an inventory of multiple different components. In addition, the position of the silencer 10 relative to the axial fan 200, namely being disposed above it so that the axial fan 200 connects to the bottom wall 22 of the duct 12, results in a relatively compact assembly. Moreover, despite the fact that air enters the duct 12 directed upwardly and is redirected longitudinally within the passageway 25, the silencer performs efficiently with limited head loss. Furthermore, the silencer 10 is relatively simple to maintain in case of soiling of the internal components of the silencer 10. Notably, if aerosolized particles accumulate on the internal components of the silencer 10 (as is possible in some applications of the roof exhaust 200), namely on the baffles 40, the acoustic material or the fiber glass membrane 37, those internal components can be easily removed and replaced on-site with new unsoiled replacements. This is contrast with many conventional silencers which have to be replaced altogether, requiring significant labor (e.g., using a crane to remove the silencer).
Modifications and improvements to the above-described embodiments of the present technology may become apparent to those skilled in the art. The foregoing description is intended to be exemplary rather than limiting. The scope of the present technology is therefore intended to be limited solely by the scope of the appended claims.

Claims

What is claimed is:

1. A silencer for a roof exhaust, comprising:

a duct defining an inlet configured to be fluidly connected with the roof exhaust and an outlet for discharging air from the duct, the duct comprising a plurality of peripheral walls that together form an exterior of the duct,

the plurality of peripheral walls comprising:

a bottom wall;

a top wall opposite the bottom wall; and

first and second side walls spaced from each other and extending from the bottom wall to the top wall,

the duct comprising a plurality of bent sheet metal wall sections fastened to each other to form the bottom wall, the top wall and the first and second side walls,

the plurality of bent sheet metal wall sections including:

a plurality of first wall sections, each first wall section of the plurality of first wall sections having a first profile;

a plurality of second wall sections, each second wall section of the plurality of second wall sections having a second profile;

a plurality of third wall sections, each third wall section of the plurality of third wall sections having a third profile,

the first, second and third profiles being shaped differently;

a plurality of baffles connected to the peripheral walls, the baffles defining a passageway of the silencer that fluidly connects the inlet to the outlet; and

an acoustic material for acoustically isolating the duct, at least part of the acoustic material being disposed between the baffles and the peripheral walls.

2. The silencer of claim 1, wherein:

the duct has a duct height measured between the bottom wall and the top wall; and

in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, the duct is symmetric about an axis bisecting the duct height.

3. The silencer of claim 1, wherein:

the duct has a duct width measured between the first and second side walls; and

in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, the duct is symmetric about an axis bisecting the duct width.

4. The silencer of claim 1, wherein, in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, each of the first and second side walls is formed by two of the first wall sections fastened to each other.

5. The silencer of claim 4, wherein each first wall section of the plurality of first wall sections comprises:

a first portion extending vertically along approximately half of a duct height measured between the bottom wall and the top wall, the first portion having a first end and a second end;

a second portion extending horizontally and laterally inwardly from the first end;

a third portion extending horizontally and laterally inwardly from the second end; and

a fourth portion extending vertically from the second portion to form a U shape together with the first and second portions.

6. The silencer of claim 5, wherein the second portion is longer than the third portion.

7. The silencer of claim 5 or 6, wherein, in the cross-section of the silencer taken along the plane, each of the first and second side walls is formed by the two of the first wall sections connected to each other by the third portions thereof.

8. The silencer of any one of claims 5 to 7, wherein each first wall section of the plurality of first wall sections further comprises a fifth portion extending horizontally and laterally inwardly from the fourth portion.

9. The silencer of any one of claims 5 to 8, wherein each first wall section of the plurality of first wall sections further comprises a sixth portion extending vertically from the third portion to form a U shape together with the first and third portions.

10. The silencer of any one of claims 5 to 9, wherein, in the cross-section of the silencer taken along the plane, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections.

11. The silencer of claim 10, wherein, in the cross-section of the silencer taken along the plane, each of the bottom wall and the top wall is formed at least in part by the second portion of each first wall section of the pair of the first wall sections.

12. The silencer of claim 10 or 11, wherein, in the cross-section of the silencer taken along the plane, in each of the bottom wall and the top wall:

the one of the third wall sections is disposed centrally and between the pair of the second wall sections; and

the pair of the second wall sections is disposed between the pair of the first wall sections.

13. The silencer of any one of claims 10 to 12, wherein:

each second wall section of the plurality of second wall sections is generally C-shaped;

each second wall section of the plurality of second wall sections has a central portion and two end portions extending from opposite ends of the central portion; and

in the cross-section of the silencer taken along the plane, for each of the bottom wall and the top wall, the central portion of each second wall section is vertically aligned with the second portion of each first wall section.

14. The silencer of claim 13, wherein:

each second wall section of the plurality of second wall sections has two lip portions extending from respective ones of the end portions; and

for each second wall section of the plurality of second wall sections, the lip portions are generally perpendicular to the end portions and extend toward a centerline of the second wall section bisecting a distance between the end portions.

15. The silencer of claim 13 or 14, wherein:

each third wall section of the plurality of third wall sections is generally step shaped; and

each third wall section of the plurality of third wall sections has a central elevated portion and two end portions extending from opposite ends of the central elevated portion; and

in the cross-section of the silencer taken along the plane, for each of the bottom wall and the top wall, the central elevated portion of the one of the third wall sections is vertically aligned with: (i) the central portion of each second wall section, and (ii) the second portion of each first wall section.

16. The silencer of claim 15, wherein:

each third wall section of the plurality of third wall sections has two lip portions extending from respective ones of the end portions of the third wall section; and

for each third wall section of the plurality of third wall sections, the lip portions are generally perpendicular to the end portions of the third wall section and extend away from a centerline of the third wall section bisecting a distance between the end portions of the third wall section.

17. The silencer of any one of claims 1 to 16, wherein each baffle of the plurality of baffles is perforated.

18. The silencer of any one of claims 1 to 17, wherein:

each baffle of the plurality of baffles comprises a plurality of baffle panels that are fastened to each other; and

each baffle panel of the plurality of baffle panels is a piece of bent sheet metal.

19. The silencer of claim 1, wherein the plurality of baffles comprises:

a first side baffle connected to the first side wall, a first part of the acoustic material being disposed between the first side baffle and the first side wall;

a second side baffle connected to the second side wall, a second part of the acoustic material being disposed between the second side baffle and the second side wall;

at least one top baffle connected to the top wall, a third part of the acoustic material being disposed between the at least one top baffle and the top wall; and

at least one bottom baffle connected to the bottom wall, a fourth path of the acoustic material being disposed between the at least one bottom baffle and the bottom wall.

20. The silencer of claim 19, further comprising a deflector pod extending between the bottom wall and the top wall, the deflector pod comprising:

a third side baffle of the plurality of baffles connected to the bottom wall and the top wall, a first sub-passage being defined between the first side baffle and the third side baffle; and

a fourth side baffle of the plurality of baffles connected to the bottom wall and the top wall, a second sub-passage between the second side baffle and the fourth side baffle,

a fifth part of the acoustic material being disposed between the third side baffle and fourth side baffle of the deflector pod.

21. The silencer of claim 20, wherein:

in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and traversing the deflector pod, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections;

each third wall section of the plurality of third wall sections is generally step shaped;

each third wall section of the plurality of third wall sections has a central elevated portion and two end portions extending from opposite ends of the central elevated portion;

the third side baffle is fastened to a first end portion of the two end portions; and

the fourth side baffle is fastened to a second end portion of the two end portions.

22. The silencer of any one of claims 1 to 21, further comprising a fiber glass membrane disposed between the baffles and the acoustic material.

23. The silencer of any one of claims 1 to 22, further comprising a plurality of adjustable legs connected to the duct, a height of each adjustable leg of the plurality of adjustable legs being adjustable to selectively set a distance between the bottom wall and a roof on which the roof exhaust is mounted.

24. The silencer of claim 1, wherein:

in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet, each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections;

in each of the bottom wall and the top wall:

the third wall section is disposed centrally and between the pair of the second wall sections; and

the pair of the second wall sections is disposed between, the pair of the first wall sections;

each first wall section of the plurality of first wall sections comprises:

a second portion extending horizontally and laterally inwardly from the first end, the second portion forming in part an exterior surface of a corresponding one of the bottom wall and the top wall;

a third portion extending horizontally and laterally inwardly from the second end;

a fourth portion extending vertically from the second portion to form a U shape together with the first and second portions; and

a fifth portion extending horizontally and laterally inwardly from the fourth portion;

each second wall section of the plurality of second wall sections is generally C-shaped and comprises:

a central portion;

two first end portions extending from opposite ends of the central portion; and

two first lip portions extending from respective ones of the first end portions, the first lip portions being generally perpendicular to the first end portions and extending toward a centerline of the second wall section bisecting a distance between the first end portions;

each third wall section of the plurality of third wall sections is generally step shaped and comprises:

a central elevated portion;

two second end portions extending from opposite ends of the central elevated portion;

two second lip portions extending from respective ones of the second end portions, the second lip portions being generally perpendicular to the second end portions and extending away from a centerline of the third wall section bisecting a distance between the second end portions;

in the cross-section of the silencer taken along the plane, in each of the bottom wall and the top wall:

a laterally outermost one of the first lip portions of each of the second wall sections is disposed above or under the fifth portion of an adjacent one of the first wall sections;

a laterally innermost one of the first lip portion of each of the second wall sections is disposed above or under a corresponding one of the second lip portions of the one of the third wall sections.

25. The silencer of claim 1, wherein:

in a cross-section of the silencer taken along a plane that is normal to the bottom wall, top wall and side walls and spaced from the inlet:

each of the first and second side walls is formed by two of the first wall sections;

each of the bottom wall and the top wall is formed by a pair of the first wall sections, a pair of the second wall sections and one of the third wall sections;

the plurality of baffles comprises:

at least one bottom baffle connected to the bottom wall, a fourth path of the acoustic material being disposed between the at least one bottom baffle and the bottom wall;

the silencer further comprises a deflector pod extending between the bottom wall and the top wall, the deflector pod comprising:

a third side baffle of the plurality of baffles connected to the bottom wall and the top wall, a first sub-passage being defined between the first side baffle and the third side baffle;

26. The silencer of claim 1, wherein:

the duct has a first end and a second end;

the bottom wall, the top wall and the first and second side walls extend from the first end to the second end;

the inlet is defined by the bottom wall;

the plurality of peripheral walls further comprises a first end wall closing off the first end of the duct; and

the outlet is defined at the second end of the duct.

27. The silencer of claim 26, further comprising a deflector pod disposed laterally between the first and second side walls, the deflector pod defining in part first and second sub-passages between the deflector pod and the first and second side walls respectively,

the deflector pod being spaced from the first end of the duct,

the inlet being disposed between the first end of the duct and an end of the deflector pod.

28. A silencer for a roof exhaust, comprising:

the plurality of peripheral walls comprising:

a bottom wall defining the inlet;

a top wall opposite the bottom wall;

the bottom wall, the top wall and the first and second side walls extending from a first end of the duct to a second end of the duct; and

a first end wall defining the first end of the duct,

29. An exhaust assembly comprising:

a roof exhaust configured to be mounted to a roof, the roof exhaust comprising a conduit for discharging air therefrom, the conduit defining a central axis; and

the silencer of claim 28 mounted to the roof exhaust,

wherein the central axis extends through the bottom wall of the duct.

30. A method for installing a silencer, comprising:

connecting a first silencer module to a roof exhaust, the first silencer module defining an inlet of the silencer configured to be in fluid communication with the roof exhaust, the first silencer module forming an acoustic plenum for attenuating sound; and

connecting a second silencer module to the first silencer module such that the first silencer module and the second silencer module form a continuous duct, the second silencer module defining an outlet of the silencer, the second silencer comprising an acoustic splitter defining two passages such that the acoustic splitter diverts air flow received by the second silencer module into the passages.

31. A silencer for a roof exhaust, comprising:

a duct defining an inlet configured to be fluidly connected with the roof exhaust, and an outlet for discharging air from the duct, the duct comprising a plurality of peripheral walls that together form an exterior of the duct;

a first silencer module defining a first part of the duct including the inlet, the first silencer module being configured to be connected to the roof exhaust, the first silencer module forming an acoustic plenum for attenuating sound; and

a second silencer module defining a second part of the duct including the outlet, the second silencer module being fastened to the first silencer module, the second silencer comprising an acoustic splitter defining two passages such that the acoustic splitter diverts air flow received by the second silencer module into the passages.