Low Noise Exhaust System

Abstract

A low noise exhaust system for use with household or industrial gas or water pumping equipment, such as kitchen or bathroom exhaust systems. The system includes a blower assembly mounted outside the building's enclosure or barrier surface to relocate the primary noise source outdoors. The blower assembly is connected to the indoor exhaust pipe via a flex tube and an inlet pipe. A filter system is mounted inside the blower assembly's inlet end to absorb high-frequency acoustic energy and filter grease. The system utilizes multiple vibration isolators and an adhesive plate to decouple the blower assembly from the building structure, and is designed with various configurations to create acoustic impedance mismatches throughout the system, thereby maximizing transmission loss and significantly reducing the indoor noise level. The outdoor mounting location, is lower than the indoor pipe connector, and facilitates grease drainage away from the indoor hood.

Description

BACKGROUND

Technical Field

The present disclosure relates generally to exhaust systems, and more specifically, to a device and system for significantly reducing the indoor noise level of exhaust systems, such as kitchen and bathroom vents, while simplifying installation.

The Conventional exhaust systems typically utilize in-duct installation of the exhaust blower equipment inside the building, which results in significant noise transmission into the indoor space. Furthermore, the noise-generating blower unit is often directly coupled to the indoor ductwork and structure, leading to vibration transmission and associated noise generation. Current solutions often involve complex installation procedures. There is a need for an exhaust system that effectively reduces indoor noise through acoustic and vibrational decoupling, is easier to install, and provides maintenance advantages.

SUMMARY

The current disclosure of invention(s) is related to a device which can be assembled into, for example, a new or old kitchen and bathroom exhaust systems and other in-door household or industrial gas or water pumping equipment. The use of the current invention(s) to the abovementioned applications is mainly for the purpose of reducing the in-door noise level of the exhaust systems in question. The other advantage of utilizing the current invention(s) is that it provides easier installation procedure than that of the conventional exhaust system which is typically utilizing the in-duct installation of the exhaust blower equipment.

The present disclosure introduces a low noise exhaust system for use with household or industrial gas or water pumping equipment, such as kitchen or bathroom exhaust systems. The system includes a blower assembly mounted outside the building's barrier or enclosure surface (e.g., roof or wall) to relocate the primary noise source outdoors. The blower assembly is connected to the indoor exhaust pipe via a flex tube and an inlet pipe. A filter system is mounted inside the blower assembly's inlet end to absorb high-frequency acoustic energy and filter grease. The system utilizes multiple vibration isolators and an adhesive plate to decouple the blower assembly from the building structure, and is designed with various configurations (e.g., changes in pipe diameter and material composition) to create acoustic impedance mismatches throughout the system, thereby maximizing transmission loss and significantly reducing the indoor noise level. The outdoor mounting location, which is preferably lower than the indoor pipe connector, also facilitates grease drainage away from the indoor hood.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may be better understood, and numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. These drawings are used to illustrate only typical embodiments of this invention, and are not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

FIG. 1 is a schematic diagram illustrating one exemplary embodiment of the low noise exhaust device.

FIG. 2 is a schematic diagram illustrating an application of the low noise exhaust device to a vertical range-top exhaust system.

FIG. 3 is a schematic diagram illustrating an application of the low noise exhaust device to a horizontal range-top exhaust system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The description that follows includes exemplary apparatus, methods, techniques, and instruction sequences that embody techniques of the inventive subject matter. However, it is understood that the described embodiments may be practiced without these specific details.

With reference to FIG. 1, one exemplary embodiment of the invention(s) is a low noise exhaust device 20 which mainly includes or consists of a blower assembly 4, a flex tube 6, a vibration isolator 5, an adhesive plate 13 and a tail pipe 7 as depicted in FIG. 1.

The blower assembly 4 includes or consists of an inlet pipe 11, a filter system 10, another vibration isolator 14, a blower unit 12 and an exhaust tail pipe 7 with a flipper 8 at the end of the exhaust tail pipe 7. Exhaust tail pipe 7 is twisted by about 75° angle at the end with a small hole 8a at the twisting point of the exhaust tail pipe 7 as shown in FIG. 1. The adhesive plate 13 is provided to attach it to the irregular roof surface or outdoor wall of the kitchen (not shown) by means of, for example, the commercially available LIQUID NAIL brand or epoxy glue which can be applied with sufficient amount on the bottom side of adhesive plate 13 as well as the irregular roof or wall surfaces (both not shown) such that the current exemplary embodiment of the invention(s) including the blower assembly 4, the vibration isolator 5, the inlet pipe 11, the flex tube 6 and the tail pipe 7 are glued on the irregular roof or outdoor wall surface. Hold-down tape 15a and hold-down tape 15b may be used to hold down the low noise exhaust device or system 20 on the roof or the wall before the abovementioned glue becomes solidified. The vibration isolator 14 provides transmission loss between blower unit 12 and filter system 10.

Filter system 10 includes or consists of a section with coarse metallic filter (not shown) and a section of filter with fine opened-cell plastic foam or fiber glass (not shown). These filter materials, firstly, absorb relatively high frequency acoustic energy and reduce acoustical transmission from the blower unit 12 towards or in the upstream direction. Any substance condensed from the suspended particles in exhaust gas, such as the grease, is also, secondly, filtered by the filter system 10 prior to reaching the blower unit 12 and it keeps the blower unit 12 from being stained. The entire filter system 10 is designed to be easily disassembled for easy cleaning and replacement purposes.

It should be noted that the inner diameter of the inlet pipe 11 and the inner diameter of exhaust pipe 7 is different from the inner diameter of the housing of the blower assembly 4, that creates relatively low frequency transmission loss due to acoustic impedance mismatch between inlet pipe 11 and blower assembly 4 as well as between the exhaust pipe 7 and blower assembly 4. The blower assembly 4 is designed to be weather proof and easy disassembled for motor-repair or replacement purposes and it is optionally enclosed with relatively heavy sheet metal for outdoor noise suppression purpose.

The vibration isolator 14 is located between the blower unit 12 and the filter system 10 to provide transmission loss by reducing the transmission of vibration induced by the blower unit 12 towards the upstream components (filter system 10, inlet pipe 11, flex tube 6, and exhaust piping/hood).

A significant noise reduction mechanism is the acoustic impedance mismatch in adjoining structures. This is achieved in several locations:

• • 1) The inner diameter of the inlet pipe 11 and the inner diameter of the exhaust pipe 7 are different from the inner diameter of the housing of the blower assembly 4, creating transmission loss for relatively low frequencies.
  • 2) The use of the flex tube 6 increases the transmission loss of the in-duct acoustic transmission compared to conventional rigid pipe.
  • 3) The inner diameter of the exhaust pipe 7 is made less than the inner diameter of the blower assembly 4 to reduce outdoor noise emission.

Outdoor Mounting and Isolation: The entire low noise exhaust device 20, including the blower assembly 4, is designed to be installed outdoor on a barrier/enclosure surface, such as a roof or wall. This is a primary source of indoor noise reduction as the noise source is relocated outside.

The adhesive plate 13 and vibration isolator 5 are used for mounting. The vibration isolator 5 is connected around the blower assembly 4, downstream from the flex tube 6, the inlet pipe 11, and the filter system 10. The adhesive plate 13 is provided to attach the combined unit (vibration isolator 5 and blower assembly 4) to the irregular roof or outdoor wall surface (not shown) using commercially available high-strength adhesive (e.g., LIQUID NAIL brand or epoxy glue).

The combination of the vibration isolator 5 and the adhesive plate 13 increases the transmission loss of vibration from the blower assembly 4 to the building structure. Furthermore, the material used for the vibration isolator 5 is different from the material of the adhesive glue, which creates a further acoustic impedance mismatch between the vibration isolator 5 and the roof/wall surface, enhancing vibrational transmission loss. Hold-down tapes 15a and 15b may be used temporarily during glue solidification.

Applications of Current Invention(s) to Low Noise Exhaust System

FIG. 2 shows an application of the current invention(s) to an exemplary embodiment of a range-top exhaust system 30 where the exhaust system 30 draws exhaust gas 1v out of a roof, barrier, or enclosure surface 9v vertically through exhaust hood 2v, exhaust pipe 3v, and a pipe connecter 11v as depicted. The blower assembly 4 of the current invention(s) is installed outdoor on the rooftop at a location lower than the pipe connector 11v as shown in FIG. 2. At installations, the flex tube 6 is connected to the pipe connector 11v and the entire blower assembly 4 along with the vibration isolator 5 is glued on the roof surface 9v through its adhesive plate 13. Since the blower assembly 4 is installed at the level below the exhaust pipe connector 11v, any substance condensed from the suspended particles in the exhaust gas 1v, such as the grease, cannot flow back to the exhaust hood 2v and it keeps the exhaust hood 2v as well as the range top relatively clean. As explained in the previous sections, the adhesive plate 13 is designed to glue or adhere the combined unit of vibration isolator 5 and the blower assembly 4 on the irregular surface of roof 9v. The substantial changes in adjoining structures or pipe configurations (e.g., between exhaust pipe 3v and flex tube 6, and between flex tube 6 and inlet pipe 11) create increased acoustic impedance mismatch, which further increases transmission loss from the blower assembly 4 back to the hood 2v. If the pipe connector 11v is made with a different inner diameter than the exhaust pipe 3v, this further enhances the impedance mismatch.

Similarly, FIG. 3 shows another application of the current invention(s) to an exemplary embodiment of a range-top exhaust system 40 where the exhaust gas 1h is drawn out of the kitchen horizontally through a wall, barrier, or enclosure surface 9h rather than being drawn out of the kitchen vertically through roof 14h. This exemplary embodiment of the current invention(s) device is similarly installed at the location lower than the pipe connector 11h. The installation of the current invention(s) exemplary embodiment of the device to this horizontal exhaust system 40 is identical to that of the previous example of a vertical exhaust system 30 except that the combined unit of vibration isolator 5 and the blower assembly 4 is attached through the adhesive plate 13 to the wall 9h rather than the roof 14h. This horizontal exhaust system 40 includes an exhaust hood 2h, an exhaust pipe 3h, and a horizontal exhaust pipe 3ah.

It should be noted that the combination of the following configurations which are incorporated in the current invention(s) contributes to the noise reduction of the respective embodiment of the exhaust system in question:

• • 1) Outdoor Installation: The noise source, blower assembly 4 is installed at the outdoor location rather than at the indoor location as in the conventional installation methodology.
  • 2) Vibration Isolator 14: The vibration isolator 14 reduces the transmission of vibration induced by the blower unit 12 towards the upstream filter system 10, the inlet pipe 11, the flex pipe 6 and all other upstream exhaust piping and hood. Reduction in vibrational transmission results in reduction in noise generation of the exhaust system in question.
  • 3) Acoustic Impedance Mismatch (Piping): In the vertical exhaust system, there is increased acoustic impedance mismatch between exhaust pipe 3v and flex pipe 6 as well as between flex pipe 6 and inlet pipe 11 due to substantial changes in pipe configurations, that increase the transmission loss from the blower assembly 4 to hood 2v. If exhaust pipe connector 11v is made with different inner diameter than that of the exhaust pipe 3v as depicted in FIG. 2, it further enhances the impedance mismatch. This reduction in acoustic transmission is identical in both vertical 30 and horizontal 40 exhaust systems.
  • 4) Flex Tube 6: The use of the flex pipe 6 increases the transmission loss of the in-duct acoustic transmission as compared to the use of conventional rigid pipe.
  • 5) Filter System 10: The filter system 10 absorbs high frequency acoustic waves hence it reduces the in-duct acoustic transmission in the upstream direction from blower assembly 4 to the exhaust hood.
  • 6) Vibration Isolator 5: The vibration isolator 5 increase the transmission loss of the vibration from the blower assembly 4 to roof 9v in vertical exhaust system 30 and to wall 9h in horizontal exhaust system 40.
  • 7) Adhesive Plate 13: The use of current adhesive plate 13 further increases the transmission loss between the vibration isolator 5 and roof 9v in vertical exhaust system and wall 9h in horizontal exhaust system, because the material used to make the vibration isolator 5 and that of the adhesive glue are different, therefore it increases the acoustic impedance mismatch.
  • 8) Exhaust Pipe 7 Diameter: The reduction in inner diameter of exhaust pipe 7 from that of the blower assembly 4 reduces the outdoor noise emission from blower assembly 4 due to acoustic impedance mismatch.

While the embodiments are described with reference to various implementations and exploitations, it will be understood that these embodiments are illustrative and that the scope of the inventive subject matter is not limited to them. Many variations, modifications, additions, and improvements are possible.

Plural instances may be provided for components, operations or structures described herein as a single instance. In general, structures and functionality presented as separate components in the exemplary configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements may fall within the scope of the inventive subject matter.

Claims

1. A system for reducing an indoor noise level of an exhaust system installed in a building, comprising:

a blower assembly mounted outside an enclosure surface of the building;

a filter system mounted inside and proximate an inlet end of the blower assembly;

an inlet pipe connected to the blower assembly; and

a flex tube connected between the inlet pipe and an exhaust pipe from the enclosure surface of the building.

2. The system of claim 1, further comprising:

a vibration isolator connected around the blower assembly at a location downstream from the flex tube, the inlet pipe, and the filter system.

3. The system of claim 1, wherein two adjoining structures, selected from the group of adjoining structures consisting of the exhaust pipe, the flex tube, the inlet pipe, an exhaust pipe connector, the blower assembly, and an inner diameter of exhaust pipe are configured to have an acoustical impedance mismatch.

4. The system of claim 1, wherein the flex tube is configured to increase the transmission loss of the in-duct acoustic transmission as compared to a conventional rigid pipe.

5. The system of claim 1, wherein the filter system comprises a section housing a coarse metallic filter and another section housing a fine opened-cell plastic foam or fiber glass, wherein the filter system is configured to absorb high frequency acoustic waves.

6. The system of claim 2, further comprising:

an adhesive plate connected to the vibration isolator and configured to adhere to the enclosure surface.

7. The system of claim 6, further comprising:

wherein the adhesive plate comprises a first material, the vibration isolator comprises a second material, and the first material is different from the second material whereby an acoustic impedance mismatch is created between the vibration isolator and the adhesive plate.

8. The system of claim 1, further comprising:

an exhaust tail pipe connected to the blower assembly; and

wherein an inner diameter of the exhaust tail pipe is less than an inner diameter of a housing of the blower assembly to create an acoustic impedance mismatch for reducing outdoor noise emission.

9. The system of claim 1, wherein the blower assembly is mounted at a location lower than a pipe connector connecting the exhaust pipe to the flex tube to facilitate drainage of condensed substances away from an indoor exhaust hood.

10. The system of claim 2, further comprising:

another vibration isolator mounted between the blower assembly and the enclosure surface.

11. A method for reducing an indoor noise level of an exhaust system installed in a building, comprising the steps of:

mounting a blower assembly outside an enclosure surface of the building; and

connecting the blower assembly to a source of indoor exhaust gas via a pipe connected through the enclosure surface of the building.

12. The method of claim 11, further comprising the step of reducing vibrational acoustic transmission from the blower assembly into the exhaust system by interposing a vibration isolator between a blower unit and an upstream filter system.

13. The method of claim 11, further comprising the step of configuring adjoining structures, selected from the group of adjoining structures consisting of the exhaust pipe, the flex tube, the inlet pipe, an exhaust pipe connector, the blower assembly, and an inner diameter of exhaust pipe, to have an acoustical impedance mismatch.

14. The method of claim 11, further comprising the step of absorbing high frequency acoustic waves in a filter system housing at least two filters mounted inside and proximate an inlet end of the blower assembly.

15. The method of claim 11, further comprising the step of increasing an acoustic impedance mismatch by making an adhesive plate of a first material and making a vibration isolator of a second material different from the first material, and adhering the vibration isolator to the enclosure surface via the adhesive plate.

16. The method of claim 11, further comprising the step of creating an acoustic impedance mismatch by making an inner diameter of a pipe connecting to the blower assembly less than an inner diameter of a housing of the blower assembly.