Air conditioning system

Details Air conditioning system Air conditioning system

1999-03-30

2001-01-30

Doerrler, William (Department: 3744)

Refrigeration

Muffler or sound dampener

C062S244000, C062S239000

Reexamination Certificate

active

06178764

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air conditioning system comprising a blower and a heat exchanger effectively used in an automotive.
2. Description of the Related Art
In recent years, what is called a “semicentral unit” has often been employed for reducing the size of an automotive air conditioning system. A semicentral unit comprises a blower arranged in front of the front passsenger seat, and heat exchangers such as an evaporator and a heat core are arranged longitudinally in the center console of an automotive vehicle (FIG.
1
). As a result, the air sent under pressure from the blower turns about 90° at a point upstream of the evaporator and flows into the evaporator.
The semicentral unit can be reduced in size as compared with what is called the transverse unit comprising a blower, an evaporator and a heat core arranged along the transverse direction of the vehicle. Also, as compared with the transverse unit, the air path from the blower to the air outlet in the cabin is shortened, and therefore the pressure loss in the air path can be reduced.
In the semicentral unit having a shorter air path than the transverse unit, however, the noise generated in the blower propagates to the interior of the cabin from the air outlet in the cabin without being sufficiently attenuated in the air-conditioning system (air-conditioning casing), thereby leading to the problem of a larger noise than the transverse unit.
Experiments and study conducted by the inventors have confirmed that a noise of about 1 kHz to 2 kHz in frequency is generated most conspicuously in what is called the face blowout mode in which the length of the air path is shortest.
SUMMARY OF THE INVENTION
In view of the problems of the prior art described above, the object of the present invention is to reduce the noise of an air conditioning system in which the air flow is turned at a point upstream of a heat exchanger in the semicentral unit.
In order to achieve the above-mentioned object, the present invention employs the following technical means. After conducting various experiments and study, the inventors have discovered that in an air conditioning system comprising a turning section
7
for changing the direction of flow in the air path
40
at a point upstream of a heat exchanger
1
, the noise sound wave generated in a blower
3
mainly impinges and is reflected on the inner wall of the turning section
7
and propagates toward the heat exchanger
1
.
In view of this, according to claim
1
of the present invention, the turning section
7
for turning the air flow toward the heat exchanger
1
has arranged thereon at least a sound absorbing member
8
in the air conditioning casing
4
.
As a result, the noise reflected on the inner wall of the turning section
7
can be effectively absorbed into, and attenuated by, the sound absorbing member
8
.
The air conditioning system according to claim
2
assumes the employment of a blower of the centrifugal type, In the absence of the scroll casing
32
or the air conditioning casing
4
, the sound wave of the noise generated in the centrifugal multi-blade fun
32
would propagate radially outward of the fan
32
. In the case where the path structure (duct structure) is formed of the scroll casing
31
and the air casing
4
as in the present invention, however, the noise generated by the centrifugal multi-blade fan
32
impinges and is reflected on the inner wall
31
a
located outward as viewed radially of the scroll casing
31
and the wall of the path connected thereto and, together with the radial air flow generated in the scroll casing
31
, propagates downstream of the air flow.
In view of this, according to claim
3
, at least a sound absorbing member
8
is arranged at the spiral end
31
b
included in the inner wall
31
a
of the scroll casing
31
.
In this way, the sound absorbing member
8
is arranged at the portion where the noise first impinges and is reflected, and therefore the noise can be positively absorbed and attenuated.
The inventors have conducted various experiments and study and have found that in the air conditioning system having a turning section
7
at a point upstream of the heat exchanger
1
, the noise in a specific frequency range is liable to resonate in the neighborhood of the connecting duct
6
.
To obviate this inconvenience, according to claim
4
hereof, at least a sound absorbing member
8
is arranged at that portion
6
a
of the connecting duct
6
for connecting the scroll casing
31
and the air conditioning case
4
which is connected to the inner wall
31
a
of the scroll casing
31
.
As a result, the noise resonating in the neighborhood of the connecting duct
6
can be effectively absorbed and attenuated.
According to claim
5
, on the other hand, at least a sound absorbing member
8
is arranged over the entire area of the turning section
7
formed in the portion of the inner wall
31
a
of the scroll casing
31
extending from the spiral end
31
b
of the scroll casing
31
to the points
6
a,
4
a
connected therewith.
In all the cases mentioned above, the noise can be effectively absorbed and attenuated by the sound absorbing member
8
arranged on the turning section
7
.
According to claim
6
, the sound absorbing member
8
is accommodated in the internal space of each expansion
12
formed by being protruded from the wall surface of the turning section
7
outward of the air path
40
.
In this way, the sectional area of the path of the blown air can be prevented from being reduced, and therefore the pressure loss in the ventilation system of the air conditioning system can be prevented from increasing and so the air flow rate can be prevented from being decreased.
According to claim
7
, the portion of the wall of the air path
40
constituting the turning section
7
is formed with at least a through hole
9
passed therethrough, which through hole
9
is closed by the sound absorbing member
8
arranged outside of the casings
31
a,
4
.
As a result, as in claim
6
, the air blow rate is prevented from being reduced, while at the same time causing the sound absorbing member
8
to effectively absorb and attenuate the sound wave of the noise.
According to claim
8
, the air conditioning system of claim
7
further comprises air blocking means
11
for blocking the flow of the air through the sound absorbing member
8
.
This prevents the air flow rate from being reduced (air leakage) which otherwise might be caused by the blown air which may pass through the sound absorbing member
8
.
According to claim
9
, on the other hand, the air conditioning system further comprises waterproofing means
13
for preventing the water from being absorbed into the sound absorbing member
8
.
Since the water is prevented from being absorbed into the sound absorbing member
8
, it is possible to prevent the reduction in the sound absorbing capacity of the sound absorbing member
8
and the generation of an offensive odor due to the decomposition of organic material in the water.
According to claim
10
, an antiseptic treatment is performed on the sound absorbing member
8
.
As a result, the generation of an offensive odor which otherwise might be caused by the decomposition of the water absorbed into the sound absorbing member
8
can be prevented. The reference characters attached to each means indicate the correspondence with the specific means included in the embodiments described below.


REFERENCES:
patent: 2236111 (1941-03-01), Philipp
patent: 2989855 (1961-06-01), Thompson
patent: 3112623 (1963-12-01), Crossman
patent: 3200609 (1965-08-01), Laing
patent: 3449924 (1969-06-01), Sudmeier
patent: 3524328 (1970-08-01), Schuster
patent: 4991406 (1991-02-01), Fujii et al.

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