JP2004066908A - Air conditioning duct - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioning duct capable of effectively reducing air conditioning noise generated in a vehicle room in accordance with operation of an air conditioning system. <P>SOLUTION: In this air conditioning duct 10, a lead-in part 12 and a lead-out part 16 are connected through a fiber duct part 14 having ventilation property and made of woven fabric. Since the fiber duct part 14 is set to have proper ventilation amount, sound wave generated in accordance with operation of an air conditioning blower can escape to the outside effectively through a pipe wall in this air conditioning duct 10. For this reason, columnar resonance does not occur easily inside the air conditioning duct 10. Consequently, since resonance of the pipe wall does not occur easily, air conditioning noise generated in the vehicle room is favorably reduced to ensure silence in the vehicle room satisfactorily. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air-conditioning duct used for an air-conditioning system, and more particularly to an air-conditioning duct for reducing air-conditioning noise radiated with the operation of the air-conditioning system.
[0002]
[Prior art]
Conventionally, as this type of air-conditioning duct, for example, an air-conditioning duct as disclosed in Japanese Patent Application Laid-Open No. H6-156053 is known. In this air conditioning duct, an opening is provided in a part of a duct body formed of a polyurethane resin or a polypropylene resin, and the opening is provided with a soft urethane foam sheet having low air permeability (1.5 ft ³ / min to ³ ft ³ / min). Is configured. With this configuration, the reflection of sound waves at the flexible urethane foam sheet portion can be reduced, and the air conditioning noise caused by the operation of the air conditioning blower can be made less likely to enter the room through the air conditioning duct.
[0003]
[Problems to be solved by the invention]
However, in the above-mentioned conventional air-conditioning duct, the reflection of sound waves can be reduced only for sound waves in a specific frequency range due to the characteristics of the flexible urethane foam sheet. For this reason, in the case of sound waves other than a specific frequency range, air column resonance may occur due to total reflection in the air conditioning duct. Further, in this case, resonance of the tube wall due to air column resonance may occur simultaneously. In these cases, the air-conditioning noise due to the resonance of the tube wall as well as the air-conditioning noise due to the air column resonance also enters the room.
[0004]
SUMMARY OF THE INVENTION
The present invention has been made to address the above-described problem, and an object of the present invention is to provide an air-conditioning duct that effectively reduces air-conditioning noise radiated into a passenger compartment due to operation of an air-conditioning system. is there.
[0005]
The feature of the present invention is that in an air conditioning duct for a vehicle, which conducts air sent from an air conditioning blower to an outlet provided in a vehicle interior, at least a part of a pipe wall of the air conditioning duct is made of a porous material having air permeability. It has been formed. In this case, the porous material per 0.0095 M ^2, good and has a breathability of ^{5 m} 3 / min from 1 m 3 / min.
[0006]
According to this, since at least a part of the pipe wall of the air conditioning duct is formed of a porous material having air permeability, sound waves generated with the operation of the air conditioning blower are transmitted to the outside through the pipe wall. You can escape effectively. For this reason, total reflection of sound waves occurring inside the air conditioning duct can be reduced, and air column resonance can be less likely to occur inside the air conditioning duct. In addition, since the air column resonance hardly occurs, the resonance of the tube wall due to the air column resonance can also be hardly generated. For this reason, the air-conditioning noise radiated into the room can be suitably reduced, and the quietness of the room can be ensured.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an air conditioning duct 10 according to the present invention, which is mounted on a vehicle and conducts air pumped from an air conditioning blower (not shown) to a driver seat outlet (not shown) provided in the vehicle interior. Is shown. The driver's seat outlet is an outlet provided at both ends of the instrument panel of the vehicle, and is an outlet provided on the driver's seat side. The air-conditioning duct 10 has an introduction portion 12 for introducing air pumped from an air-conditioning blower, a fiber duct portion 14 joined to the introduction portion 12 at one end, and joined at the other end of the fiber duct portion 14. And a lead-out portion 16.
[0008]
The introduction portion 12 is formed in a tubular shape with a resin material (for example, polyethylene or the like). The end of the introduction portion 12 on the air introduction side (the side connected to the air conditioning blower) is formed in a square shape in accordance with the shape of the air discharge port of the air conditioning blower.
[0009]
As shown in FIG. 2, the fiber duct portion 14 is formed of a woven fabric in which a warp yarn 14a extending in the axial direction of the fiber duct portion 14 and a wire 14b and a weft yarn 14c extending in the circumferential direction are woven. It is formed in a shape. In addition, since the wire 14b is woven into the woven fabric, the formed predetermined tubular shape is maintained for a long time. The outer surface of the fiber duct portion 14 is impregnated with a resin 14d for adjusting the stitch size. For this reason, the pipe wall of the fiber duct portion 14 is adjusted so as to have an appropriate ventilation rate. In order to ensure a necessary and sufficient air flow, the appropriate air flow rate is preferably 5 m ³ / min or less per 0.0095 m ^{2 at} a pressure difference of 9 kPa between the inside and outside of the pipe wall, It is particularly preferable to adjust the rate to about 1 m ³ / min per 0.0095 m ^{2 in} order to secure a noise reduction effect.
[0010]
The lead-out portion 16 is formed in a cylindrical shape with a resin material (for example, polyethylene or the like). The end of the outlet portion 16 on the air outlet side (the side connected to the outlet in the vehicle compartment) is formed in a square shape in accordance with the shape of the outlet. In addition, a bracket 16a is formed integrally with the lead-out portion 16, and is fixed to a predetermined position on the back surface of the instrument panel by a bolt (not shown).
[0011]
The joining portion between the fiber duct portion 14 and the lead-out portion 16 is first inserted outside the joining end portion of the lead-out portion 16 by inserting a predetermined amount of the fiber duct portion 14, and is fixed by rivets. Then, the entire periphery of the overlapped portion is completely adhered and sealed with an adhesive (for example, a hot-melt adhesive). The joint between the introduction portion 12 and the fiber duct portion 14 is made in the same manner.
[0012]
Next, regarding the air-conditioning noise reduction effect of the air-conditioning duct 10 (having a ventilation rate of 1 m ³ / min per 0.0095 m ² ) configured as described above, the air-conditioning noise radiated from the outlet into the vehicle interior and the pipe An explanation will be given based on the measurement result of the air-conditioning noise transmitted through the wall and radiated into the vehicle interior. In order to clearly show the air-conditioning noise reduction effect of the air-conditioning duct 10, an air-conditioning duct made entirely of a resin material having no air permeability (hereinafter, this air-conditioning duct is referred to as a conventional duct) was prepared as a sample and evaluated. Was carried out. The graphs shown in FIGS. 3 and 4 described below plot the sound pressure level with respect to the measurement frequency. The sound pressure level of the air conditioning duct 10 is indicated by a solid line, and the sound pressure level of the conventional duct is indicated by a broken line. Is shown. Also, in the graph, the sound pressure level is higher as the air conditioning noise radiated into the vehicle interior is higher, and the sound pressure level is lower as the air conditioning noise radiated into the vehicle interior is lower.
[0013]
First, the air-conditioning noise radiated into the vehicle interior from the outlet will be described with reference to the graph shown in FIG. Note that the air conditioning noise radiated from the outlet into the vehicle compartment is collected and measured by a microphone installed near the outlet. As a result of the measurement, the sound pressure level of the air conditioning duct 10 is lower than the sound pressure level of the conventional duct in the entire measurement frequency range.
[0014]
This can be considered as follows. That is, in the inside of the air-conditioning duct 10 and the conventional duct, the sound wave generated by the operation of the air-conditioning blower travels in the direction of the outlet using air as a transmission medium. At this time, the sound wave collides with the inner surface of the tube wall. In a conventional duct, since the pipe wall has no air permeability, sound waves are repeatedly reflected on the inner surface of the pipe wall. As a result, air column resonance occurs in the pipe of the conventional duct, and the sound wave is amplified by the air column resonance and reaches the outlet. Then, it can be considered that the arrived sound wave is radiated into the vehicle interior from the outlet as a large air conditioning noise. Therefore, it can be considered that the measured sound pressure level is high.
[0015]
On the other hand, in the air-conditioning duct 10, most of the sound waves generated by the operation of the air-conditioning blower are transmitted to the wall of the fiber duct portion 14 because the pipe wall of the fiber duct portion 14 has an appropriate air permeability. Can be released into the outside air. Thereby, in the pipe of the air-conditioning duct 10, the reflection of sound waves can be reduced, and it can be considered that air column resonance is less likely to occur. For this reason, the air conditioning noise radiated from the outlet is reduced, and the sound pressure level of the air conditioning duct 10 can be considered to be lower than that of the conventional duct.
[0016]
Next, the air-conditioning noise radiated into the vehicle cabin due to resonance of the pipe wall will be described based on the graph shown in FIG. The air-conditioning noise radiated into the cabin due to the resonance of the pipe wall is the air-conditioning noise radiated into the vehicle cabin through the instrument panel in an actual vehicle, and thus is collected by a microphone installed on the panel. Measured. As a result of the measurement, the sound pressure level of the air-conditioning duct 10 shows almost the same sound pressure level as that of the conventional duct over the entire measurement frequency range. In particular, the sound pressure level around 470 Hz is lower than that of the conventional duct. And is significantly lower.
[0017]
This can be considered as follows. That is, as described above, in the conventional duct, the pipe wall resonates at 470 Hz due to the air column resonance generated in the pipe, and the sound wave accompanying this resonance enters the vehicle cabin via the instrument panel. Radiated as air conditioning noise. For this reason, it can be considered that the sound pressure level is high around 470 Hz.
[0018]
On the other hand, in the air-conditioning duct 10, sound waves generated by the operation of the air-conditioning blower can escape to the outside of the tube wall of the fiber duct portion 14, so that air column resonance hardly occurs and resonance hardly occurs. Thus, it can be considered that the sound pressure level of the air conditioning duct 10 is lower than that of the conventional duct. Since the sound wave that has passed through the pipe wall of the fiber duct portion 14 is greatly attenuated when passing through the pipe wall of the fiber duct portion 14, it is rapidly attenuated in the outside air.
[0019]
As can be understood from the above description, according to the air-conditioning duct 10, since the fiber duct portion 14 is set to have an appropriate ventilation amount, the sound wave generated by the operation of the air-conditioning blower is transmitted to the pipe wall. Through, can effectively escape to the outside. Therefore, air column resonance hardly occurs in the air conditioning duct 10, and resonance of the tube wall can be hardly generated. For this reason, the air-conditioning noise radiated into the vehicle interior can be suitably reduced, and quietness in the vehicle interior can be ensured satisfactorily.
[0020]
Further, in the above embodiment, the fiber duct portion 14 was formed into a tubular shape with a woven fabric, but instead, the air conditioning duct 10 was formed by a fiber duct portion 14 ′ formed by forming a nonwoven fabric into a tubular shape. The present invention may be modified and implemented. Hereinafter, this modified example will be described in detail, but the same portions as those in the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted.
[0021]
As shown in detail in FIG. 6, the fiber duct portion 14 'is formed by crimping a nonwoven fabric (for example, felt or the like) with respect to a wire 14'b extending in the circumferential direction of the fiber duct portion 14' to form a predetermined pipe. It is shaped into a shape. In addition, a resin 14'd is impregnated and applied to the outer surface of the fiber duct portion 14 'in order to adjust the air permeability of the fiber duct portion 14'. For this reason, the fiber duct portion 14 'also has appropriate air permeability.
[0022]
Also in the air-conditioning duct 10 constituted by the fiber duct portion 14 ', since the fiber duct portion 14' is set to have an appropriate ventilation amount, the sound wave generated by the operation of the air-conditioning blower is transmitted through the pipe. Through the wall, it can effectively escape to the outside. Therefore, air column resonance hardly occurs in the air conditioning duct 10, and resonance of the tube wall can be hardly generated. For this reason, the air-conditioning noise radiated into the vehicle interior can be suitably reduced, and quietness in the vehicle interior can be ensured satisfactorily.
[0023]
In the above embodiment, the air conditioning blower and the driver's seat outlet are connected by the air conditioning duct 10. On the other hand, the air-conditioning blower and the air outlet on the passenger seat side (air outlets provided at both ends of the instrument panel of the vehicle, and the air outlet provided on the passenger seat side), the air-conditioning blower and other It is needless to say that an air outlet of the vehicle, for example, an air outlet provided at a substantially central portion of an instrument panel of a vehicle may be connected to the air conditioning duct 10. In this case, the same effect as in the above embodiment can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating an air conditioning duct according to an embodiment.
FIG. 2 is a sectional view showing in detail a structure of a fiber duct portion of the air conditioning duct shown in FIG.
FIG. 3 is a graph for explaining an effect of reducing air conditioning noise radiated into a vehicle cabin from an outlet of an air conditioning duct shown in FIG. 1;
FIG. 4 is a graph for explaining an effect of reducing air conditioning noise radiated into a vehicle interior due to resonance of a pipe wall of the air conditioning duct shown in FIG. 1;
FIG. 5 is a sectional view showing in detail a structure of a fiber duct portion according to a modification of the present invention.
[Explanation of symbols]
10: air conditioning duct, 12: introduction part, 14, 14 ': fiber duct part, 16: lead-out part.

Claims (2)

In the air-conditioning duct that conducts the air sent from the air-conditioning blower to the outlet provided in the room,
An air-conditioning duct, wherein at least a part of a pipe wall of the air-conditioning duct is formed of a porous material having air permeability. The porous material is
0.0095 M ^{2 per} air-conditioning duct, as described in the claim 1 from 1 m 3 / min and has a breathability of ^{5 m} 3 / min.

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