Patent Application
20210372145
The present invention relates to rooftop exhaust systems that exhaust air from buildings.
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.
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.
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.
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.
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.
With further reference to the drawings, an exhaust system is shown therein and indicated generally by the numeral 10. See
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.
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
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
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
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.
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
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° F. and can run up to four hours when exposed to a temperature of 1000° 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.
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”.
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.
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.
