U.S. patent application number 16/889845 was filed with the patent office on 2021-12-02 for rooftop exhaust system for exhausting air from a building.
This patent application is currently assigned to Captive-Aire Systems, Inc.. The applicant listed for this patent is Captive-Aire Systems, Inc.. Invention is credited to William Brian Griffin, Joshua J. Hess.
Application Number | 20210372145 16/889845 |
Document ID | / |
Family ID | 1000004884259 |
Filed Date | 2021-12-02 |
United States Patent
Application |
20210372145 |
Kind Code |
A1 |
Hess; Joshua J. ; et
al. |
December 2, 2021 |
Rooftop Exhaust System for Exhausting Air from a Building
Abstract
The present invention entails a rooftop exhaust system for a
building. The exhaust system includes a motor that is configured to
directly drive a fan. The fan during the course of operation
generates a negative pressure on the upstream side of the fan. This
negative pressure is utilized to induce outside cooling air into a
shroud that partially encloses the motor. Cooling air passing
through the shroud contacts the motor and heat associated with the
motor is transferred to the cooling air after which the cooling air
exits the shroud.
Inventors: |
Hess; Joshua J.; (Washington
Boro, PA) ; Griffin; William Brian; (Columbia,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Captive-Aire Systems, Inc. |
Raleigh |
NC |
US |
|
|
Assignee: |
Captive-Aire Systems, Inc.
Raleigh
NC
|
Family ID: |
1000004884259 |
Appl. No.: |
16/889845 |
Filed: |
June 2, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04F 17/026 20130101;
E04F 17/04 20130101 |
International
Class: |
E04F 17/02 20060101
E04F017/02; E04F 17/04 20060101 E04F017/04 |
Claims
1. A method of exhausting air from a building with a rooftop
exhaust system comprising a housing, a motor, a shroud at least
partially encompassing the motor, and a fan directly driven by the
motor and wherein the motor, shroud and fan are generally disposed
in the housing, the method comprising: driving the fan and inducing
exhaust air to move from the building through the housing and out
an outlet of the rooftop exhaust system; generating a negative
pressure in a zone that lies on an upstream side of the fan and
adjacent an opening provided in the shroud; wherein the negative
pressure induces outside cooling air to enter one or more air
cooling inlets formed in the housing; directing the cooling air
from the air cooling inlet in the housing to one or more conduits
extending through the housing and between the air cooling inlet in
the housing and one or more air cooling inlets formed in the
shroud; directing the cooling air from the air cooling conduit
through the air cooling inlet of the shroud and into and through
the shroud; cooling the motor within the shroud by contacting the
motor with the cooling air passing through the shroud; discharging
the cooling air from the shroud through the opening; and after
discharging the cooling air from the shroud, mixing the cooling air
with the exhaust air.
2. The method of claim 1 wherein the shroud includes a side wall
structure that extends around the motor and a bottom that lies
underneath the motor; and wherein the opening is formed in the top
of the shroud and faces the fan.
3. The method of claim 1 wherein the exhaust air passes around and
outside of the shroud and wherein substantially no exhaust air
directly contacts the motor.
4. A rooftop exhaust system for exhausting exhaust air from a
building comprising: a housing having one or more side walls and
configured to be mounted on the roof of the building; a motor
mounted in the housing; a direct drive fan operatively connected to
the motor for inducing the exhaust air to flow into an inlet end of
the housing and through the housing; a shroud disposed in the
housing and extending at least partially around the motor and
configured to generally isolate the motor from exhaust air passing
from the building through the housing; the shroud is generally
enclosed except for an open top that faces the fan; one or more air
cooling inlets formed in the shroud; one or more air cooling inlets
formed in the side wall of the housing; one or more air cooling
conduits connected between the air cooling inlet formed in the
shroud and the air cooling inlet formed in the housing; wherein the
fan is configured to generate a negative pressure zone on an
upstream side of the fan and by virtue of the negative pressure
zone, the fan is configured to induce cooling air to flow from
outside of the building into the air cooling inlet in the housing,
through the air cooling conduit and into and through the shroud
where the cooling air cools the motor; and wherein the rooftop
exhaust system is configured to discharge the cooling air from the
open top of the shroud where the cooling air mixes with the exhaust
air.
5. A method of exhausting smoke from a building fire with a rooftop
exhaust system comprising a housing, a motor, a shroud at least
partially encompassing the motor, and a fan directly driven by the
motor and wherein the motor, shroud and fan are generally disposed
in the housing, the method comprising: driving the fan and inducing
smoke to move from the burning building through the housing and out
an outlet in the rooftop exhaust system; as the building burns,
running the motor continuously when the motor is exposed to a
temperature of up to 572.degree. F. and running the motor for a
period of four hours or less when the motor is exposed to a
temperature of 573.degree. F. to 1000.degree. F., wherein running
the motor under said temperature conditions and during a building
fire include: generating a negative pressure in a zone that lies on
an upstream side of the fan and adjacent an opening provided in the
shroud; wherein the negative pressure induces outside cooling air
to enter one or more air cooling inlets formed in the housing;
directing the cooling air from the cooling air inlet in the housing
to one or more cooling conduits extending through the housing and
between the air cooling inlet in the housing and one or more air
cooling inlets formed in the shroud; directing the cooling air from
the air cooling conduit through the air cooling inlet of the shroud
and into and through the shroud; cooling the motor within the
shroud by contacting the motor with the cooling air passing through
the shroud; discharging the cooling air from the shroud through the
opening in the shroud; and wherein the discharged cooling air from
the shroud mixes with the smoke being exhausted by the exhaust
system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to rooftop exhaust systems
that exhaust air from buildings.
BACKGROUND OF THE INVENTION
[0002] Many buildings employ rooftop exhaust systems for exhausting
air from the building. Typically, rooftop exhaust systems include a
motor that drives a fan. In some applications, the air being
exhausted by the exhaust fan can be relatively hot and this can
have adverse effects on the motor. In these cases, the motor is
asked to perform in a hot environment. This hot environment impacts
the performance and life of the motor which in turn results in the
motor requiring replacement too often and also contributes to
increased maintenance cost.
[0003] Hence, there is a need for a rooftop exhaust system designed
to minimize heat buildup in and around the motor. Further, there is
a need to incorporate into the exhaust system features that
positively cool the motor when the exhaust fan is operating.
SUMMARY OF THE INVENTION
[0004] The present invention relates to a rooftop exhaust system
for exhausting hot or warm air from a building. The exhaust system
includes a motor which drives a fan. To protect the motor from hot
or warm air passing through the exhaust system, a partially open
shroud extends around the motor. As the fan is driven, a region of
negative pressure forms between the fan and the motor. The shroud
is open to this negative pressure. Due to the negative pressure,
ambient cooling air from outside of the building is directed into
and through the shroud. As the cooling air moves through the
shroud, it contacts the motor and in the process cools the
motor.
[0005] In one particular embodiment, the motor and fan are
supported inside a housing having a wall. The shroud is also
mounted in the housing and extends around the sides and bottom of
the motor but is open at the top. The shroud generally isolates and
protects the motor from hot air that is being exhausted from the
building. However, the shroud is open at the top. Hence, the
opening in the top of the shroud lies below the fan. The wall of
the housing is provided with one or more cooling air inlets. The
cooling air inlets formed in the housing are connected to one or
more air cooling conduits. The air cooling conduits are in turn
connected to cooling air inlets formed in the shroud. As noted
above, when the fan is operating, a region of negative pressure
lies between the fan and the motor. Since the shroud is open at the
top, it is open and exposed to this negative pressure. This
negative pressure that lies about the top opening in the shroud
causes ambient cooling air to be induced into the cooling air
inlets in the housing. From there, the cooling air enters the
cooling air conduits that directs the cooling air into and through
the shroud and out the open top thereof where the cooling air joins
with the exhaust air from the building. The continuous flow of
cooling air through the shroud results in the cooling air
continuously contacting the motor and in the process cooling the
motor.
[0006] Other objects and advantages of the present invention will
become apparent and obvious from a study of the following
description and the accompanying drawings which are merely
illustrative of such invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic elevational view showing the rooftop
exhaust system incorporated into the roof of a building.
[0008] FIG. 2 is a perspective view of the rooftop exhaust
system.
[0009] FIG. 3 is another perspective view of the rooftop exhaust
system showing it from the bottom.
[0010] FIG. 4 is a schematic sectional view showing the exhaust
system, as well as the flow of the exhaust air and cooling air.
DESCRIPTION OF PREFERRED EMBODIMENT
[0011] With further reference to the drawings, an exhaust system is
shown therein and indicated generally by the numeral 10. See FIG.
1. In the embodiment illustrated, the exhaust system is what is
generally referred to as an upblast-type. Conceptionally, the
present invention can be employed with other types of exhaust
systems. Exhaust system 10 is used for general ventilation. As
shown in FIG. 1, the exhaust system 10 is installed on the roof of
a building. Exhaust system 10 is mounted on a curb 13 which in turn
is supported on the roof of the building. In operation, the exhaust
system 10 exhausts air from the building, resulting in exhaust air
being drawn towards the roof of the building and into and through
the curb and out the exhaust system.
[0012] Exhaust system 10 includes a housing indicated generally by
the numeral 12. It is appreciated that the specific design and
construction of the housing can vary from one application to
another. In any event, in the embodiment illustrated herein,
housing 12 includes a lower housing 12A that can assume a generally
rectangular, square, or round configuration. In the particular
embodiment illustrated, the lower housing 12A includes a plurality
of side walls 12C. Housing 12 further includes an upper housing 12B
that extends upwardly from the lower housing 12A and functions as
an air duct for directing exhaust air upwardly through a portion of
the exhaust system. Upper housing 12B is sometimes referred to as
an air shaft. In the embodiment illustrated, the upper housing 12B
assumes a generally circular form.
[0013] Exhaust system 10 is provided with means for inducing
exhaust air to move upwardly through the exhaust system where the
air is exhausted to the atmosphere. In the application illustrated,
the housing 12A is mounted on a curb 13. See FIG. 1. Hence, when
the curb 13 is used, exhaust air from the building moves from the
building through the curb 13 and then through the exhaust system
10. Various fan and motor arrangements can be incorporated into the
exhaust system. In an exemplary embodiment, the exhaust system
includes a propeller 16 which is directly driven by an axially
aligned motor 18. Motor 18 is supported by a frame structure in the
housing 12. Note that the propeller 16 and motor 18 are axially
aligned with the upper circular housing or air shaft 12B. It is
appreciated by those skilled in the art that a fan wheel may be
used in lieu of the propeller 16. It is understood and appreciated
by those skilled in the art that other types of fans can be
incorporated into the exhaust system 10. As used herein, the term
"fan" includes propeller-type fans and wheel-type fans. As noted
above, in the arrangement shown in the drawings, propeller 16 is
directly driven by the motor 18. Generally when a direct drive is
employed, the propeller is mounted to the drive shaft of the motor
18 or to an extension therefrom. In other cases, the propeller or
fan wheel can be driven from a side mounted motor through a belt
drive.
[0014] Supported at the outlet end of the upper housing 12B are one
or more dampers 30. In the embodiment illustrated, there is
provided two dampers 30 with the dampers being pivotally mounted
about a transverse axis about the top of the upper housing 12B.
Thus, the dampers 30 are supported, at least indirectly, by the
upper housing or air shaft 12B. As seen the drawings, the dampers
30 are disposed over the propeller 16 and motor 18. Since the
dampers 30 are pivotally mounted, they are moveable from a
generally horizontally closed position to a raised or inclined open
position. See FIG. 2. In a normal operation, the force of the air
being exhausted upwardly through the exhaust system is sufficient
to open the dampers 30 so as to permit the exhaust air to
escape.
[0015] A shroud 32 is mounted in the housing 12. Shroud 32 can
assume various shapes and configurations. In the embodiment
illustrated in the drawings, the shroud 32 includes multiple sides,
a bottom and an open top. Note that the shroud 32 is disposed
around the motor 18. See FIGS. 3 and 4. Shroud 32 generally
isolates the motor 18 from the grease laden exhaust air passing
through the housing 12. As seen in the drawings, shroud 32 extends
approximately the full length of the motor 18. That is, the walls
of the shroud 32 can terminate below the top of the motor, even
with the top of the motor or above the top of the motor. As noted
above, the specific design of the shroud 32 and its orientation in
and around the motor 18 can vary. Also, as people of ordinary skill
in the art appreciate, the material used to construct the shroud 32
can vary but it is preferable to use a material that provides a
good thermal insulation.
[0016] The exhaust system 10 of the present invention is designed
to induce ambient cooling air from outside of the building into the
shroud for the purpose of cooling the motor 18. This is achieved by
the provision of one or more air cooling inlets 34 formed in the
side walls of the housing 12A. In the case of the embodiment
illustrated, there are two air cooling inlets 34 but it is
understood that there could be one or a multiplicity of air cooling
inlets. There is also provided air cooling inlets 36 formed in the
shroud 32. Here again in this particular embodiment, there are two
air cooling inlets 36 formed in the walls of the shroud 32. Air
cooling inlets 34 and 36 are connected by air cooling conduits 38.
As will be appreciated from the discussion below, the function of
the air cooling conduits is to channel cooling air from the air
cooling inlets 34 and the housing 12A to the shroud 32.
[0017] During the operation of the exhaust system 10, the propeller
16 will generate a negative pressure zone 40 on the upstream side
of the fan 16. This negative pressure zone 40 is illustrated
particularly in FIG. 4. Note that the propeller 16 is fixed to the
output shaft of the motor 18 and that the top of the motor is
spaced relatively close to the propeller 16 and the open top of the
shroud 32. The negative pressure zone 40 stretches across the open
top of the shroud 32. Because the top of the shroud is open, the
shroud and the interior thereof includes the negative pressure
generated by the propeller 16 during the operation of the exhaust
system. More particularly, the negative pressure in and about the
shroud causes outside or ambient cooling air to be induced into the
air cooling conduits 34 formed in the side wall 12C of the housing
12A. From the air cooling conduits 34, the cooling air is induced
to enter the air cooling conduits 38 after which the cooling air
flows into and through the internal areas of the shroud 32. This
cooling air contacts the motor 18 and heat is transferred from the
motor to the cooling air as it flows through the shroud 32. Because
the top of the shroud 32 is open, the cooling air that exits the
shroud 32 is mixed with the exhaust air and together they are
exhausted from the exhaust system via the upper housing 12B. In
FIG. 4, the cooling air and the exhaust air are referred to by
arrows. Arrows with dotted line tails represent the exhaust air and
arrows with full line tails represent the cooling air.
[0018] The exhaust system of the present invention is useful for
more than cooling the motor 18 during normal operations. In
addition, the exhaust system is designed to keep the motor 18
running in case of a building fire. With the addition of the
cooling conduits and the shroud, the motor 18 can run continuously
when exposed to a temperature of up to 572.degree. F. and can run
up to four hours when exposed to a temperature of 1000.degree. F.
In the case of a building fire, the exhaust system pulls smoke out
of the building and this improves visibility inside of the building
for occupants and firefighters.
[0019] In the specification and claims, the term "configured to" is
used. The term "configured to" is defined to mean "designed to".
The term "configured to" is more narrow than terms such as "for"
and "capable of".
[0020] From the foregoing specification and discussion, it is
appreciated that the present invention is a relatively simple,
efficient and cost effective way of cooling the motor 18 that forms
a part of a rooftop exhaust system. It is particularly efficient
and cost effective since the negative pressure generated by the
propeller in the course of exhausting air is employed to induce the
cooling air into and through the shroud 32.
[0021] The present invention may, of course, be carried out in
other specific ways than those herein set forth without departing
from the scope and the essential characteristics of the invention.
The present embodiments are therefore to be construed in all
aspects as illustrative and not restrictive and all changes coming
within the meaning and equivalency range of the appended claims are
intended to be embraced therein.
* * * * *