Patent Application
20180281559
This document relates generally to the motor vehicle equipment field and, more particularly, to an acoustic air duct and an air extraction system having nesting expansion chambers 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 airflow 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. A first channel of the plurality of channels includes alternating expansion chambers and constriction zones.
Each expansion chamber may have a first cross sectional area of between 320 mm2 and 3,200 mm2 and a first total volume of between 8,182 mm3 and 487,680 mm3. Each constriction zone may have a second cross sectional area of between 80 mm2 and 800 mm2 and a second total volume of between 2,032 mm3 and 121,920 mm3. Further, the plurality of channels may be circular in 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.
A second channel of the plurality of channels may also include alternating expansion chambers and constriction zones. In some of the many possible embodiments, the expansion chambers of the first channel nest in the constriction zones of the second channel and the expansion chambers of the second channel nest in the constriction zones of the first channel.
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. A first channel of the plurality of channels includes alternating expansion chambers and constrictions zones extending in series along the length of the first channel.
A second channel of the plurality of channels may also include alternating expansion chambers and constriction zones extending in series along the length of the second channel. In some of the many possible embodiments, the expansion chambers of the first channel nest in the constriction zones of the second channel and the expansion chambers of the second channel nest in the constriction zones of the first channel.
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. The plurality of channels may be made from an acoustic material.
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 wherein a first channel of the plurality of channels includes alternating expansion chambers and constriction zones.
The method may further include the step of internesting the first channel with a second channel of the plurality of channels also having alternating expansion chambers and constriction zones. In such a configuration, the expansion chambers of the first channel nest in the constriction zones of the second channel and the expansion chambers of the second channel nest in the constriction zones of the first channel.
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 one of many possible embodiments, each expansion chamber 28 may have a first cross sectional area of between 320 mm2 and 3200 mm2 and each constriction zone 30 may have a second cross sectional area of between 80 mm2 and 800 mm2. Further each expansion chamber 28 may have a first total volume of between 8,182 mm3 and 487,680 mm3 while each constriction zone 30 may have a second total volume of between 2,032 mm3 and 121,920 mm3.
The plurality of channels 22 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 of the acoustic air duct 16 may also be made from an acoustic material if desired. The plurality of channels 22 may be made integral with the outer wall 18 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.
In use, air traveling through the airflow passageway 20 of the acoustic air duct 16 from the trim panel inlet 12 to the air extractor 14 passes through the plurality of channels 22 by entering the various inlet ends 24. That air then passes serially through the alternating expansion chambers 28 and constriction zones 30 before exiting through the various outlet ends 26.
This air movement through the expansion chambers 28 and constriction zones 30 reduces NVH thereby reducing any transmission of noise through the air duct 16. Significantly, this is done without compromising airflow through the passenger compartment of the motor vehicle since the airflow passageway 20 provides a predetermined cross sectional area necessary to meet body leakage requirements for providing reduced door closing effort and optimal airflow in the passenger compartment so as to allow efficient and effective performance of the heating, ventilation and air conditioning (HVAC) system.
The resulting well ventilated, reduced noise environment enhances the satisfaction of the motor vehicle operator.
As illustrated in
Reference is now made to
Consistent with the above description, a method is provided for reducing noise transmitted through an air duct 16 such as illustrated in
The method may further include the step of internesting the first channel 221 with one or more second channels 222 also having alternating expansion chambers 28 and constriction zones 30. As a consequence, the expansion chambers 28 of the first channel 221 nest in the constriction zones 30 of the second channel(s) 222 and the expansion chambers of the second channel(s) nest in the constriction zones of the first channel.
Still further, the method may include making the plurality of channels 22 (including 221 and 222) from an acoustic material. Further, the method may include the step of extending the acoustic air duct 16 from an air inlet, such as a trim panel inlet 12 to an air extractor 14. Still further, the method may also include the step of providing the internal airflow passageway 20 with a cross sectional area sufficient to provide a predetermined leakage airflow from a passenger compartment of a motor vehicle.
In summary, the air extraction system 10 incorporates the air inlet/trim panel inlet 12, the air extractor 14 and an acoustic air duct 16 connecting and providing fluid communication between the air inlet/trim panel inlet 12 and the air extractor 14. Advantageously, the acoustic air duct 16 meets 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 duct 16 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 may extend through any portion or even all of the entire length of the elongated airflow passageway 20. Further, while the channels 22 of the illustrated embodiment are circular in cross section, it should be appreciated that they may assume substantially any other shape including, but not necessarily limited to elliptical, polygonal, as well as regular and irregular shapes. The channels 22 may also be all of the same cross sectional area or different cross sectional areas. 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.
