Patent Application
20180281558
This document relates generally to the motor vehicle equipment field and, more particularly, to an acoustic air duct, an air extraction system for a motor vehicle as well as to a related method of reducing noise transmitted through an air duct.
A motor vehicle air extraction system provides a number of functions, allowing proper air flow inside a passenger cabin of a motor vehicle, controlling window fogging and even reducing door closing effort. Such an air extraction system incorporates an inlet such as a trim panel inlet, an air extractor and an air duct connecting the trim panel inlet to the air extractor.
In order to accommodate a desired airflow inside the passenger cabin, that air duct is ideally designed to have a large diameter and no expansion chamber. In order to control noise, vibration and harshness (NVH), that air duct is ideally designed to have a small diameter and an expansion chamber. This document relates to a new and improved acoustic air duct and a new and improved air extraction system uniquely designed and adapted to meet these seemingly conflicting requirements. A related method of reducing noise transmitted through an air duct is also provided.
In accordance with the purposes and benefits described herein, a new and improved acoustic air duct is provided. That acoustic air duct comprises an outer wall defining an elongated internal airflow passageway and a plurality of channels extending along the airflow passageway within the outer wall.
The plurality of channels may have a helical configuration so as to provide a tortuous path to reduce noise transmission through the acoustic air duct.
In some of the many possible embodiments of the acoustic air duct, at least one channel of the plurality of channels may have a circular cross-section. In other of the many possible embodiments of the acoustic air duct, at least one channel of the plurality of channels may have a polygonal cross section. In at least one embodiment of the many possible embodiments of the acoustic air duct, the plurality of channels may form a honeycomb cross section.
In some of the many possible embodiments of the acoustic air duct, the plurality of channels may be made from an acoustic material. For purposes of this document, an acoustic material means a material designed to absorb sound.
In accordance with an additional aspect, an air extraction system is provided for a motor vehicle. That air extraction system comprises an inlet, such as a trim panel inlet, an air extractor and an acoustic air duct extending from the trim panel inlet to the air extractor. The acoustic air duct includes an outer wall defining an elongated airflow passageway and a plurality of channels extending along the airflow passageway within the outer wall.
The plurality of channels may have a helical configuration so as to provide a tortuous path to reduce noise transmission through the acoustic air duct.
In some of the many possible embodiments of the air extraction system, at least one channel of the plurality of channels has a circular cross section. In some of the many possible embodiments of air extraction system, at least one channel of the plurality of channels has a polygonal cross section. In some of the many possible embodiments of air extraction system, the plurality of channels form a honeycomb cross section.
The plurality of channels may be made from an acoustic material.
Each channel of the plurality of channels may have a cross sectional area of between 200 mm2 and 2000 mm2. Each channel of the plurality of channels may have a length of at least 7.62 cm.
In accordance with still another aspect, a method is provided for reducing noise transmission through an air duct. That method comprises dividing an internal airflow passageway in the air duct with a plurality of channels.
The method may further include the step of providing the plurality of channels in a helical configuration. In addition, the method may include the step of providing the plurality of channels with a honeycomb cross section.
The method may also include the step of making the plurality of channels from an acoustic material. Still further, the method may include the step of extending the air duct from an air inlet, such as a trim panel inlet, to an air extractor. In addition, the method may include the step of providing the internal airflow passageway with a cross sectional area sufficient to provide a predetermined leakage airflow from an interior compartment of a motor vehicle.
In the following description, there are shown and described several preferred embodiments of the acoustic air duct, the air extraction system and the related method of reducing noise transmitted through an air duct. As it should be realized, the acoustic air duct, the air extraction system and the related method are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the acoustic air duct, the air extraction system and method as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.
The accompanying drawing figures incorporated herein and forming a part of the specification, illustrate several aspects of the acoustic air duct, the air extraction system and the related method and together with the description serve to explain certain principles thereof.
Reference will now be made in detail to the present preferred embodiments of the acoustic air duct, air extraction system and related method of reducing noise transmitted through an air duct, examples of which are illustrated in the accompanying drawing figures.
Reference is now made to
As illustrated in
In the embodiment illustrated in
The outer wall 18 of the acoustic air duct 16 illustrated in
The plurality of channels 22 in the acoustic air duct 16 of the embodiment illustrated in
The plurality of channels within the outer wall 18 may extend through any portion or the entire airflow passageway 20. In one particularly useful embodiment, the plurality of channels 22 has a length of at least 7.62 cm. The plurality of channels 32 in the outer wall 28 of the acoustic air duct 26 may also have a length of at least 7.62 cm.
In any of the possible embodiments, the plurality of channels 22, 32 may assume any number of different cross sectional shapes including, but not limited to, circular, oval, polygonal, regular or even irregular.
In any of the possible embodiments, the plurality of channels 22, 32 may be made from an acoustic material. Examples of acoustic materials that may be utilized to absorb or reduce sound include but are not necessarily limited to polyurethane, plastomer such as ethylene-alpha olefin copolymers and polyesters such as polyethylene terephthalate (PET). The outer wall 18, 28 of the acoustic air duct 16, 26 may also be made from an acoustic material if desired. The plurality of channels 22, 32 may be made integral with the outer wall 18, 28 such as by co-extrusion therewith or the plurality of channels may be provided by a separate partition body that is secured within the outer wall. Additive manufacturing may also be used.
Reference is now made to
Each channel 42 may be made from an acoustic material if desired. In addition, each channel 42 may have a cross sectional area of between 200 mm2 and 2000 mm2 as well as a length of least 7.62 cm. The outer wall 38 may also be made of an acoustic material if desired to aid in reducing NVH. Of course, the helical configuration of the plurality of channels 42 provides a tortuous path that functions to reduce the transmission of noise into the passenger compartment of the motor vehicle through the trim panel inlet 12.
Consistent with the above description, a method is provided for reducing noise transmitted through an air duct such as illustrated at 16, 26, 36 and in
The method may include providing those plurality of channels 42 in a helical configuration as illustrated in
As illustrated in
In summary, the air extraction system 10 incorporates the trim panel inlet 12, the air extractor 14 and an acoustic air duct 16, 26 or 36 connecting and providing fluid communication between the air inlet/trim panel inlet 12 and the air extractor 14. Advantageously, any of the acoustic air ducts 16, 26, 36 meet the seemingly conflicting requirements for optimizing airflow through the passenger compartment of a motor vehicle while also substantially reducing NVH. As such, the acoustic air ducts, 16, 26, 36 and air extraction system 10 both represent a significant advance in the art.
The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. For example, the channels 22, 32, 42 may extend through any portion or even all of the entire length of the elongated airflow passageways 20, 30, 40. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.
