JPS6390415A - Automobile air conditioner - Google Patents

Abstract

PURPOSE:To improve the absorbing performance of the noise of a low frequency component by attaching a sound absorbing material which is formed by sticking a thin plate made of a nonporous organic elastic material to the front face side of a thick board made of a porous elastic material, to the inner wall face of an air conditioner air duct. CONSTITUTION:A sound absorbing material D is attached to the inner wall face of the bottom part of a casing body 1 positioned opposite to the air suction port 1B of a blower A by means of an adhesive. This sound absorbing material D is formed by sticking a thin plate 11 of a nonporous organic elastic material, e.g., chloroprene rubber to the front face side of a thick board of a porous elastic body, e.g., soft polyethylene form. Also, this sound absorbing material D is equally stuck to other necessary parts of the inner wall of an air conditioner air duct. By this structure, noise of chiefly a low frequency component generated by the blower can be absorbed while preventing increase in blast resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an air conditioner for an automobile in which measures are taken to reduce blowing noise.

[Prior art 1] The general configuration of an air conditioner for an automobile is that a heater core serving as a hot water heat exchanger for heating is installed in a box-shaped ventilation passage having an inlet for conditioned air and an outlet for conditioned air. It mainly consists of an air conditioning duct that houses an evaporator as a cooling heat exchanger, and a centrifugal blower that allows the air to be conditioned to flow into and out of the duct.

[Problem to be Solved by the Invention 1] Although modern automobiles, especially passenger cars, have reached a nearly satisfactory technical level in terms of driving performance and quietness of their engines, there are still problems with the air blowing noise generated from air conditioners. A sufficient solution has not yet been found.

Send J! l Inside the scroll casing of a centrifugal blower, which is the source of noise, the pulsating airflow from the multi-blade impeller causes turbulence in various parts of the casing, which has a complex shape. It generates noise as compression waves.

As a conventional means for attenuating such noise, it is first considered to attach a sound absorbing material, such as a flexible polyurethane foam board, to the inside of the scroll casing. The sound absorption mechanism of this type of sound absorbing material is that the sound absorbing material receives the vibrational energy of air compression waves and causes a symbiotic phenomenon, and this resonance energy activates the motion of the molecules that make up the sound absorbing material, and this kinetic energy is converted into thermal energy and dissipated.

Each material has its own unique synergistic properties, and flexible polyurethane foams can be synergized by high-frequency sound waves of 1,0OOH7 or higher. However, when we examine the frequency distribution of the sound waves generated from a centrifugal blower, we find that it is 5001.
Since the peak appears in the low region below -1 z, the above means cannot be an effective noise reduction measure.

In addition, since the surface of soft sponge board-based sound absorbing materials, such as soft polyurethane foam, has extremely uneven surfaces, the wind speed distribution in a ventilation duct in which this sponge board is attached to an inner wall surface as a sound absorbing material is shown schematically. As shown in FIG. 9, the sponge plate acts as a ventilation resistor, resulting in a decrease in the feed Jifit. As a result of an experiment using a model air conditioning duct with the air flow rate set to a value of 400 m/h, we found that by pasting a sound-absorbing sponge board (thickness 15 mm) on the inner wall of the duct, the air flow between the inlet and outlet of the duct was reduced. A pressure loss of 51nlllAQ is generated,
The amount of air blown decreased by 20/m3/h.

An object of the present invention is to provide an air conditioner for an automobile that can effectively absorb noise biased toward low frequency components generated from a blower and incorporates a sound absorbing material that does not increase ventilation resistance. purpose.

[Means for Solving the Problems] In order to achieve the above object, an air conditioner for an automobile according to the present invention is provided with an air conditioner for air conditioning including a heat exchanger and a blower. At least one of the inner wall surfaces of the blower and the air conditioning ventilation duct is provided with non-porous bamboo on the surface side of a thick plate made of a porous elastic material.
A sound-absorbing material with a thin plate made of a highly elastic material was applied.

[Operations and Effects of the Invention] The automotive air conditioner having the above configuration has a non-woven material with a relatively low vibration resonance frequency on the surface side of a thick plate made of a porous elastic material with a relatively high vibration resonance frequency. By applying sound absorbing material made by pasting thin plates of porous organic elastic material to the required locations within the ventilation duct,
It is possible to effectively attenuate the vibration energy of the noise sound waves that are biased towards low frequency components generated from J.

Further, since the surface of the sound absorbing material is covered with a smooth non-porous plate, the presence of the sound absorbing material does not cause the disadvantage of increased ventilation resistance in the access path.

[Example] The configuration of the present invention will be specifically described below based on an example shown in the drawings.

FIGS. 1 to 5 all show one embodiment of the device,
1 and 2 show the blower section, FIG. 3 shows a partially cutaway side view of the entire device, and FIGS. 4 and 5 show the air conditioning ventilation duct section, respectively.

As shown in Figure 3, the overall features of the device are that the air intake port of the air conditioning duct B, which serves as an air conditioning ventilation path, is connected to the discharge port 1C of the centrifugal blower, and the air suction port 1B of the blower A is An inside/outside air switching box C is attached to the inside/outside air switching box C for selectively introducing outside air or vehicle interior air as conditioned air into the air conditioning duct B.

In the centrifugal blower +1A, a multi-blade fan 2 is housed in a scroll casing in which a casing body 1 part and a top wall 1A part are combined with a fastening fitting 6, and a boss part '2A of the fan 2 is attached to the bottom surface of the casing body 1. It is attached to the output shaft of the fan drive motor 3 using a bracket 7.

Send J! A sound-absorbing material is applied to the bottom inner wall surface of the casing body 1, which is located opposite to the air suction port 1B of IIIA, using an adhesive so as to cover the entire surface thereof.

In this embodiment, the sound absorbing material includes a thin plate 10 of chloroprene rubber as a non-porous geometric elastic material on the surface side of a thick plate 10 of flexible polyurethane foam as a porous elastic material.
It is constructed by pasting 1 together.

The material of the flexible polyurethane foam has a 50% compression hardness of 50 g/ci and an air permeability of 1 to 10 CC/SeC/
Cd (according to JIS, L-1004 test method)
A plate with a thickness of 14 mm was selected.

It has been estimated from a series of experimental results that it is appropriate to select the surface density of the non-porous organic elastic material 11, which indicates the weight per unit area, in the range of 10" to 10 JO/m. A 1.0-brane rubber plate having a thickness of 1.0 mm was attached to the surface of the flexible polyurethane foam plate 10 using a chloroprene rubber adhesive.

Conventional centrifugal feeding of sound-absorbing material with a thickness of 15 mm J! la m
If the coating is applied directly to the inner bottom surface of the scroll casing A, the volume and shape of the air passage inside the casing will change, and the characteristics of the blower will also change. was positioned lower than a conventional blower by the thickness of the sound-absorbing material 15 mm, and the back side of the sound-absorbing material was fixed to this lowered bottom surface 1C using a polypropylene adhesive.

The inside/outside air switching box C, whose air outlet is connected to the air inlet 1B of the centrifugal blower A, has an outside air inlet 4A on the top surface of the case 4 made of hard synthetic resin, which has a trapezoidal shape, and one An inside air suction port 4B is provided on the inclined wall surface, and both suction ports are selectively opened and closed via a remote control mechanism by an inside/outside air switching damper 5 that rotates around a rotating shaft 5A.

Air conditioning duct B is a box-shaped case 2 made of hard synthetic resin.
0, the evaporator 21 (as a heat exchanger for generating cold air) sequentially moves from the air intake port toward the outlet, and selectively transfers some or all of the cold air to the heater core (as a heat exchanger for generating hot air) on the downstream side. Temperature control damper for inflow (not shown)
It is composed of a temperature control area 22 equipped with a heater core 23, an air mix area 24 for mixing cold air and warm air that bypasses the heater core and flows downstream, and a center ventilation blower is provided downstream of the air mix area 24. Exit 25
, a heat outlet 26 and a defrost outlet 27 are provided. 30 is a cold air outlet (for example, a side ventilation outlet 2) in which the cold air generated after passing through the evaporator 21 is short-circuited without passing through the downstream side where ventilation resistance is large.
8) A cold air bypass duct with sufficiently low ventilation resistance.

A sound absorbing material can be applied to the inner wall surface of the case 20 of the air conditioning duct B in order to sufficiently reduce the noise that could not be absorbed by the suction RtlD installed inside the casing of the air blower nA by 1%. In addition, in a place where a sound absorption effect is likely to occur, for example, the place indicated by 20A in FIG. A bulge is provided facing the outside of the case.

The bulging portion 20A is illustrated in FIGS. 4 and 5. Reference numeral 12 is a first section retainer for fixing the sound-absorbing material, and reference numeral 31 is an assembly member for assembling the case 20, which has an upper and lower halves.

Since the operation of the apparatus of the above embodiment is not the same as that of the conventional apparatus, a description thereof will be omitted.

Next, the sound absorbing effect of the sound absorbing material according to the present invention will be described.

The sound absorption mechanism of the sound absorption UPI has already been explained, but the difference in the wood quality of this sound absorption material O compared to the conventional sound absorption materials used in automobile air conditioners is that the sound absorption (sound absorption) ) It consists of a laminated body of two types of sound-absorbing materials with different characteristics, and moreover, the lower layer of the laminated body is a relatively thick plate-shaped porous sound-absorbing material, and the upper layer is a non-porous sound absorbing material. Since a structure in which sound absorbing materials made of elastic materials are strung together is being explored, the sound absorbing materials in the upper and lower layers can independently attenuate the noise sound waves corresponding to their respective natural resonance frequencies, and both the upper and lower sound absorbing materials can at least Since aiFIJ is performed integrally near the bonding interface, so to speak, the composite absorption S of both sound absorbing materials is also generated, and the soft synthetic resin foam rest 10 on the lower layer side has a relatively high frequency The thin plate 11 as a non-porous rubber bullet board can effectively absorb the vibration energy of a wide range of sound waves, ranging from the sound waves of g @ sound waves to relatively low frequency noise sound waves. .

In addition, the surface of the porous foam board 10 is replaced with a non-porous rubber board 1.
By covering with 1, the problem of increased ventilation resistance in the channel due to the presence of OJl and sound absorbing material mentioned at the beginning does not occur. FIG. 8 and FIG. 9 schematically show the output velocity distribution state in the air conditioning duct of the device of the present invention and a conventional device that does not use a sound absorbing material, respectively. Such effectiveness is naturally 1':4 for conventional porous sound absorbing materials with a synthetic resin film attached to the surface as a surface protective coating, but in this case, we expect sound absorbing performance from the surface coating material. I can't do that at all.

FIG. 6 shows actual measurement data of the sound absorption effect when the device shown in FIG. 3 was operated under conditions where the ventilation outlet 25 was opened and a blowout of 400 m/h ff1fa was obtained. At this time, the fan drive motor 93 whose rotation speed is variable was set to the maximum rotation state (Ili). In addition, a sound-collecting microphone was placed at the driver's left ear.

For comparison, measurement data for a conventional air conditioner made of the same M4 construction is also shown as a broken line graph, except that no sound-absorbing material is used, and therefore the absorption and storage bulge 20A is also missing.

As can be read from this graph, the level of the air conditioning system using the sound-absorbing material according to the present invention: the level of the noise generated from a is 200 to 1,5001 compared to the system not using the S-absorbing material.
(There is a clear decrease in the Z frequency band, 5
It can be seen that it is possible to effectively attenuate the ventilation noise that contains many noise sound waves of 001-12 or less. The overall noise level was 65 dB(A) for the conventional device;
8 decreased to 0.3 dB(A).

FIG. 7 shows a composite sound-absorbing material with a thickness of 15 mm used in the above embodiment device and a material with a thickness of 15 mm that is the same as the sound-absorbing material 10.
He presented experimental data comparing the sound absorption properties of two types of sound absorbing materials, including a flexible polyurethane foam board. From this graph, it can be seen that the sound absorption [) according to the present invention can extremely effectively perform its role v1 against the air blowing noise with a predominant low frequency component.

In the above example, a soft polyurethane foam is used as the porous elastic material, but other soft synthetic materials such as soft vinyl chloride, polyethylene, polystyrene, boli-O-pyrene, and polyamide can also be used. It is also possible to use resilient porous materials such as foam or non-woven fabrics.

In addition, as the non-porous (geoelastic material) silicone rubber, silicone rubber,
In addition to elastomers such as butyl rubber, acrylic rubber, various synthetic rubbers, and natural rubber, soft synthetic resins with high rubber elasticity, such as polyurethane, polyvinyl chloride, polyethylene, polypropylene, polyamide, polyethylene terephthalate, and polyethylene terephthalate, can be used. Can be done. It is also possible to use the porous elastic material or non-porous organic elastic material described above, in which inorganic powder/granules or U&fibrous material is mixed as a filler and whose vibration absorption properties are investigated.

Furthermore, the objects of the present invention can also be achieved by using a thin film material of metal such as lead, copper, aluminum, or iron in place of the non-porous organic elastic board material or in combination with this material.

The thickness of each of the thick plate 10 made of porous elastic material and the thin plate 11 made of non-porous elastic material is determined because a compact outer shape and light weight are particularly required for automobile air conditioners. However, the upper limit value is naturally constrained, and the desirable thickness of the plate depends on the quality of the materials used, but the combination of the materials of the two types of materials to be bonded together, A sound absorption test was carried out while varying the combinations of board thicknesses (as a result of -, the porous elastic material board 10 had a thickness of 5 to 30 mm, and the non-porous organic elastic board 11 had a thickness of 0.01 to 2 mm. It was confirmed that the thickness was appropriately selected.

[Brief explanation of the drawing]

FIGS. 1 to 5 all show one embodiment of the device,
Figure 1 is a side sectional view of the air blower, Figure 2 is an exploded view of the blower, Figure 3 is a partially cutaway front view showing the overall configuration of the device, and Figures 4 and 5 are air conditioning ventilation ducts. FIG. 3 is a diagram illustrating a method for applying a sound absorbing material to the inner wall surface of the vehicle. FIG. 6 is a data graph C that compares the noise generation level between the device shown in FIG. 3 and a conventional device that is the same as the device shown in FIG. 3 except that no sound-absorbing material is used. FIG. 7 is a data graph of an experiment comparing the sound absorption characteristics of the sound absorbing material according to the present invention and a conventional sound absorbing material. Figures 8 and 9 schematically depict the ventilation resistance in the air duct when the sound absorbing material according to the present invention and the conventional sound absorbing material are installed in the air duct for air conditioning, respectively. FIG. 3 is a side sectional view of the il tract. In the diagram A...Blower B...Air conditioning oil j/α path
C...Hei outside air switching box 1...Scroll casing of feeder 2...Multi-blade fan 1B...Suction port 1
0...Porous elastic material 11...Non-porous organic elastic material TO+11(D)...Sound absorbing material 20...Air conditioning duct case 20A...Bulging part for storing sound absorbing material

Claims (1)

[Scope of Claims] 1) An air conditioner for an automobile comprising an air conditioning ventilation passage containing a heat exchanger and a blower, wherein at least one of the inner wall surfaces of the blower and the air conditioning ventilation passage is made of porous elastic material. 1. An air conditioner for an automobile, characterized in that a sound absorbing material in which a thin plate made of a non-porous organic elastic material is attached is attached to the surface side of a thick plate made of the material. 2) The air conditioner for an automobile according to claim 1, wherein the porous elastic material has a thickness of 5 to 30 mm. 3) The air conditioner for an automobile according to claim 1 or 2, wherein the non-porous elastic material has a thickness of 0.01 to 2 mm. 4) Claims 1 to 3, characterized in that the porous elastic material is a synthetic resin foam such as polyurethane, vinyl chloride, polyethylene, polypropylene, polyamide, or polystyrene. An air conditioner for an automobile according to any one of the above. 5) The porous elastic material is a rubber foam such as silicone rubber, butyl rubber, acrylic rubber, NBR rubber, SBR rubber, or natural rubber. The air conditioner for an automobile according to any one of Item 3. 6) The non-porous elastic material is a synthetic resin such as polyurethane, vinyl chloride, polyethylene, polypropylene, polyamide, polyethylene terephthalate, or polybutylene terephthalate, or an inorganic powder added to these materials. An air conditioner for an automobile according to any one of claims 1 to 5, characterized in that the air conditioner is made of a material mixed with granules or fibrous material as a filler. 7) The non-porous elastic material is silicone rubber-based, butyl rubber-based, acrylic rubber-based, NBR rubber-based, SBR rubber-based,
Any one of claims 1 to 5, characterized in that it is a rubber material such as natural rubber, or a material in which inorganic powder, granules, or fibrous material is mixed as a filler. The automotive air conditioner described in . 8) The non-porous elastic material is lead, copper, aluminum,
An air conditioner for an automobile according to any one of claims 1 to 5, characterized in that the air conditioner is made of metal foil such as iron. 9) The blower is a centrifugal blower equipped with a scroll casing, and the adsorbent is deposited on an inner wall surface of the scroll casing that faces the suction port. The automotive air conditioner according to any of item 8.