DESC:FIELD OF THE INVENTION
The present invention relates generally to a field of heating, ventilation, and air conditioning (HVAC) system for a vehicle, and more specifically to an ultra-light weight and high noise absorbent foam material for HVAC duct in a vehicle.
BACKGROUND OF THE INVENTION
Vehicles include a climate control system for maintaining the interior climate of the occupant compartment of the vehicle. Air handling for the climate control system is provided by a heating, ventilation and air conditioning (HVAC) system. The HVAC system includes a network of ducts and vents for transferring a flow of air in through and out of the vehicle. The airflow in the occupant compartment enhances occupant comfort, provides for anti-fogging of windows, as well as other features. The transfer of fresh air into the occupant compartment and of stale air out of the occupant compartment is typically accomplished via an interconnected system of air vents and air ducts. The air duct openings are positioned in various locations in the occupant compartment, such as in the instrument panel, a pillar, or the quarter panel, or the like.
The air ducts are commonly used to distribute the flow from the compressor through piping arrangements to the occupant compartment of the vehicle. One function of an air duct is to provide for the controlled flow of air into the occupant compartment of the vehicle. Another function of an air duct is to provide for the controlled flow of air out of the occupant compartment of the vehicle.
Typically, air ducts in a HVAC system are made of High-density polyethylene (HDPE) using blow moulding technique. The density of the HDPE ducts is 0.96 kg/m3 which is quite high, hence weight of the duct made of HDPE is high. Also, there is need for maintaining gap of greater than 5mm between the interfacing components when duct made of HDPE material is used, to avoid buzz, squeak & rattle (BSR) noise. BSR noise are caused by the structural problems of connections between components that are generated by a difference in errors or materials.
Thus, there is need in the art for a HVAC duct that improves the performance of the HVAC system by reducing the BSR issues while also minimising thermal losses during the air flow.
OBJECTIVE OF THE INVENTION
These objectives are provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This objective are not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
An important objective of the invention aims at providing an ultra-light weight and high noise absorbent foam material for HVAC duct in a vehicle.
Another object of the invention is to achieve BSR improvement even with critical clearances of less than 3 mm between interface components.
Yet another object of the invention is to keep transfer of noise or vibration through the air ducts to a minimum.
Another object of the invention is to minimize the thermal losses inside duct during air flow.
Object of the present invention is not limited to the above mentioned problem. Other technical problems that are not mentioned will become apparent to those skilled in the art from the following description.
SUMMATY OF THE INVENTION
According to an aspect of the present invention a heating, ventilation, and air conditioning (HVAC) system for a vehicle, comprises a duct, and the duct on an outside surrounded by at least a trim panel, a wiring harness, and a body in white (BIW), wherein the duct is made of a foam material formed of weight percent proportioning in the range of Polypropylene (PP) 45-55%, Polyethylene (PE) 35-45% and remaining Nitrogen.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawing, illustrating by way of example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail with reference to an embodiment which is illustrated in the following figures:
Figure 1 is top view illustrating HVAC duct in an occupant compartment of a vehicle, according to an embodiment of the present invention;
Figure 2 shows HVAC duct of figure 1, according to an embodiment of the present invention;
Figure 3 is cut-away view of figure 1 along A-A shows clearance between duct to pp, according to an embodiment of the present invention;
Figure 4 is cut-away view of figure 1 along C-C shows clearance between duct to wiring harness, according to an embodiment of the present invention;
Figure 5 is cut-away view of figure 1 along D-D shows clearance between duct to BIW, according to an embodiment of the present invention;
Figure 6 shows graph illustrating sound absorbency test results, according to an embodiment of the present invention; and
Figure 7 shows graph illustrating rattle performance test results, according to an embodiment of the present invention.
Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION OF THE INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
Figures 1-5 illustrates heating, ventilation, and air conditioning (HVAC) system in an occupant compartment of a vehicle and cut-away view of figure 1 along various axis. A HVAC system for a vehicle, comprising a duct (100), and the duct (100) on outside surrounded by at least a trim panel (102), a wiring harness (104), and a body in white (BIW) (106). The HVAC duct (100) is made of a foam material formed of weight percent proportioning in the range of Polypropylene (PP) 45-55%, Polyethylene (PE) 35-45% and remaining Nitrogen.
In a preferred embodiment of the invention the foam material can be formed of weight percent proportioning Polypropylene (PP) 50%, Polyethylene (PE) 40% and Nitrogen 10%.
In the present invention HVAC duct is made of an ultra-light weight and high noise absorbent foam material to achieve BSR improvement even with critical clearances of less than 3mm between interface components. Foam is light weight, light density material having density 0.23Kg/m3. The duct using said foam material is made by dual expansion blow molding process. Figure 3 shows design illustrating reduced clearance 1.36mm between duct to trim panel for duct made of foam according to the present invention. Figure 4 shows design illustrating reduced clearance 1.34mm between duct to wiring harness for duct made of foam according to the present invention. Figure 5 shows design illustrating reduced clearance that is 3.00mm between duct to BIW for duct made of foam according to the present invention.
One advantage of the present invention is that BSR improvement even with critical clearances of less than 3 mm between interface components. Another advantage is that the material absorbs high noise and thus reduces the transfer of noise or vibration through the air ducts to a minimum. In a typical duct noise, vibration, harshness (NVH) improvement can be by 4Db. A further advantage of the present invention is that the material has high thermal resistance and thus minimized thermal losses inside duct during air flow. Yet another advantage of the present invention is weight saving by 50% than the conventional material duct.
According to an embodiment of the present invention sound absorbency test was conducted for duct made of different materials viz. plastic duct made of High-density polyethylene (HDPE) having 1.5mm thickness, foam duct made of Polyethylene (PE) and Polypropylene (PP) materials having thickness 1.5mm and 2.00mm.
Figure 6 illustrates sound absorbency test results for the tested materials. Among the tested materials foam duct having thickness 1.5mm and 2.00mm showed better sound absorbency rate at rated frequency as compared to the duct made of HDPE material.
According to another embodiment of the present invention rattle performance test was conducted between duct made of HDPE and foam materials considering various test conditions. Figure 7 illustrates rattle performance test results for the tested materials. From the figure it is observed the soft duct which is made of foam material showed better noise reduction under all considered conditions as compared to the duct made of HDPE material.
The experimental test results described above shows the superior material property of the foam material as compared to the HDPE or any known materials.
While the preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited to the precise construction herein disclosed, and the right is reserved to all changes and modifications coming within the scope of the invention.
Although there has been shown and described the preferred embodiment of the present invention, it will be readily apparent to those skilled in the art that modifications may be made thereto which do not exceed the scope of the appended claims. Therefore, the scope of the invention is only to be limited by the following claims.

,CLAIMS:
1. A heating, ventilation, and air conditioning (HVAC) system for a vehicle, comprising:
a duct (100), the duct (100) surrounded by at least a trim panel (102) from outside;
a wiring harness (104); and
a body in white (BIW) (106), wherein
the duct (100) is made of a foam material formed of weight percent proportioning in the range of Polypropylene (PP) 45-55%, Polyethylene (PE) 35-45% and remaining Nitrogen.
2. The HVAC system as claimed in claim 1, wherein the foam is an ultra-light weight and high noise absorbent light weight, light density material having density of 0.23 Kg/m3.
3. The HVAC system as claimed in claim 1, wherein the duct (100) is made by a dual expansion blow molding process.
4. The HVAC system as claimed in claim 1, wherein the foam material reduces buzz, squeak, and rattle (BSR) between the duct (100) and the trim panels (102) such that clearance achieved is 1.36 mm.
5. The HVAC system as claimed in claim 1, wherein the foam material reduces buzz, squeak, and rattle (BSR) between the duct (100) and wiring harness (104) such that clearance achieved is 1.34 mm.
6. The HVAC system as claimed in claim 1, wherein the foam material reduces buzz, squeak, and rattle (BSR) between the duct (100) and the the BIW (106) such that clearance achieved is 3.00 mm.
7. The HVAC system as claimed in claim 1, wherein the thickness of the duct (100) is in the range of 1.5 mm to 2.00 mm.