Acoustics – Sound-modifying means – Muffler – fluid conducting type
Reexamination Certificate
2000-12-18
2002-07-09
Nappi, Robert E. (Department: 2837)
Acoustics
Sound-modifying means
Muffler, fluid conducting type
C181S229000, C181S249000
Reexamination Certificate
active
06415888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a muffler, and more particularly to a muffler used in a reciprocating compressor.
2. Description of the Conventional Art
Generally, mufflers applied to compressors are classified into a suction muffler connected to a fluid suction section of a compressor and a discharge muffler connected to a fluid discharge section of a compressor.
Such suction and discharge mufflers serve to attenuate a pulsation phenomenon periodically generated during repeated fluid suction and discharge operations of a compressor, to which those mufflers are applied, thereby allowing the compressor to smoothly suck and discharge fluid. These mufflers also serve to shield impact noise generated in opening and closing operations of a valve and noise resulting from flowing of fluid so that those noise cannot be externally transmitted from the compressor, thereby achieving a silent operation of the compressor.
FIG. 1
is a sectional view illustrating an example of a hermetic reciprocating compressor respectively provided with conventional mufflers at suction and discharge sections thereof.
As shown in
FIG. 1
, the reciprocating compressor includes a casing
1
filled with a desired amount of oil, an electric motor mechanism installed in a lower portion of the casing
1
in the interior of the casing
1
and adapted to generate a drive force in response to electric power externally applied thereto, and a compression mechanism installed at an upper portion of the casing
1
in the interior of the casing
1
and adapted to receive the drive force from the electric motor mechanism so as to conduct gas sucking and compressing operations.
The compression mechanism includes a frame
2
fixedly mounted to the casing
1
in the interior of the casing
1
, a cylinder
3
fixedly mounted to a portion of the frame
2
, and a drive shaft
5
extending vertically through a central portion of the frame
2
while being fitted in a rotor
4
B included in the electric motor mechanism so that it is coupled to the rotor
4
B. The drive shaft
5
is provided at an upper end thereof with an eccentric portion. The compression mechanism also includes a connecting rod
6
coupled to the eccentric portion of the drive shaft
5
and adapted to convert a rotating movement into a reciprocating movement, a piston
7
connected to the connecting rod
6
and slidably received in the cylinder
3
in such a fashion that it reciprocates in the cylinder
3
, a valve assembly
8
coupled to the cylinder
3
and adapted to control suction and discharge of refrigerant gas, and a head cover
9
coupled to the valve assembly
8
and defined with a desired discharge space. The compression mechanism further includes a suction muffler
10
coupled to a portion of the head cover in such a fashion that it communicates with a suction inlet of the valve assembly
8
, and a discharge muffler DM mounted to the cylinder
3
in such a fashion that it communicates with a discharge outlet of the valve assembly
8
.
In association with respective orientations of the above-mentioned elements, the upward direction corresponds to the direction toward the upper portion of the plane in FIG.
1
.
As shown in
FIG. 2
, the muffler
10
is provided with a muffler inlet
11
directly communicated with a refrigerant line SP extending through the casing
1
or arranged in the interior of the casing
1
.
The muffler inlet
11
communicates with a first reservoir S
1
defined, in the form of an expansion chamber, in a central portion of the muffler
10
.
The first reservoir S
1
communicates with a second reservoir S
2
defined, in the form of an expansion chamber, beneath the first reservoir S
1
via a first conduit having a small cross-sectional area. A third reservoir S
3
is defined, in the form of an expansion chamber, above the first reservoir S
1
. The third reservoir S
3
serves as the Helmholtz reservoir.
The second reservoir S
2
communicates with a muffler outlet
12
communicating with the valve assembly
8
via a second conduit
16
extending vertically into the second reservoir S
2
through the third reservoir S
3
.
A resonant aperture
17
is formed at an upper portion of the second conduit
16
arranged in the third reservoir S
3
so that it constitutes the Helmholtz Resonator, together with the third reservoir S
3
.
In
FIGS. 1 and 2
, the reference numeral or character
4
A denotes a stator,
18
an oil discharge port, C a support spring, and O an oil feeder. In addition, the reference numerals
13
and
14
denote partition walls, respectively.
Now, an operation of the hermetic reciprocating compressor provided with the above mentioned conventional mufflers will be described.
When the rotor
4
A is rotated by a mutual electromagnetic force generated between the stator
4
A and the rotor
4
B in response to electric power applied to the electric motor mechanism, the drive shaft
5
rotates along with the rotor
4
B. The rotation of the drive shaft
5
is converted into straight reciprocating movements by the connecting rod
6
coupled to the eccentric portion of the drive shaft
5
. The reciprocating movements is transmitted to the piston
7
which, in turn, reciprocates in the interior of the cylinder
3
to compress refrigerant gas and to discharge the compressed refrigerant gas. Pressure pulsation and noise, which may be generated during the above-mentioned operations of the piston
7
, flow in a direction opposite to the flowing direction of the refrigerant gas so that they are attenuated by the muffler
10
.
The procedure for attenuating the pressure pulsation and flowing noise by the conventional mufflers will now be described.
During a stroke of the piston
7
from an upper dead point to a lower dead point, refrigerant gas filled in the second reservoir S
2
is forced to be sucked into the interior of the cylinder
3
, that is, a compression chamber, via the second conduit
16
and muffler outlet
12
while opening a suction valve of the valve assembly
8
. Simultaneously, new refrigerant gas is introduced into the second reservoir S
2
via the muffler inlet
11
, first reservoir S
1
and first conduit
15
. On the other hand, during a stroke of the piston
7
from the lower dead point to the upper dead point, the suction valve of the valve assembly
8
is closed. In this state, a discharge valve of the valve assembly
8
is simultaneously opened. Therefore, compressed refrigerant gas is discharged into a discharge space DS defined in the head cover
9
.
In the procedure in which the suction and discharge of refrigerant gas are repeated, a repetitive pressure pulsation occurs continuously in the muffler
10
and head cover
9
. Such pressure pulsation is propagated to each flow path defined in the muffler
10
. As this pressure pulsation passes the second conduit
16
, second reservoir S
2
, first conduit
15
, and first reservoir S
1
, they are gradually attenuated, and finally dissipated. Therefore, there is little pressure pulsation at the muffler inlet
11
. Accordingly, the refrigerant gas can be smoothly introduced.
Meanwhile, noise generated during the suction of refrigerant gas is converted into heat energy in accordance with a diffusion and dissipation thereof occurring when it passes through the conduits
15
and
16
, and reservoirs S
1
, S
2
and S
3
, so that it is attenuated. In particular, noise of a specific frequency is attenuated by the helmholtz Resonator composed of the resonant aperture
17
of the second conduit
16
and the third reservoir S
3
.
In the above mentioned noise attenuation method, in which attenuation of noise is achieved using a simple resonation effect and the Helmholtz Resonator, however, it is necessary to use an excessively large volume for each reservoir. Therefore, there is a problem in that the whole muffler volume is undesirably increased.
Furthermore, the procedure of converting pulsation energy of noise into heat energy in accordance with a diffusion and dissipation causes an increase in muffler temperature resulting
An Kwang Hyup
Lee In Seop
Myung Hwan Joo
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Lockett Kim
Nappi Robert E.
LandOfFree
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