Pumps – With muffler acting on pump fluid
Reexamination Certificate
2000-12-11
2002-03-26
Freay, Charles G. (Department: 3746)
Pumps
With muffler acting on pump fluid
C417S902000
Reexamination Certificate
active
06361290
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a hermetic compressor (hereinafter referred to as a compressor) for use with electric refrigerators, air conditioners and the like, and more particularly to a suction muffler included in the compressor.
BACKGROUND ART
The principle of refrigeration in electric refrigerators, air conditioners and the like is described below briefly. A compressor is used to compress a refrigerant gas to raise its pressure. The high-pressure refrigerant gas is cooled and liquefied. When the liquefied gas vaporizes in an evaporator, the gas extracts vaporization heat from the air inside a refrigerator or a room. The evaporated refrigerant gas is returned to the compressor. The above-mentioned operation is repeated, thereby lowering the temperature of the air inside the refrigerator or the room. In the present invention, the above-mentioned change of the refrigerant from being discharged from the compressor to returning to the compressor is referred to as a refrigeration cycle.
Refrigerants based on hydrofluorocarbon (HFC) or hydrocarbon (HC) not including chlorine are used as refrigerants. In recent years, these refrigerants have been used frequently instead of chlorofluorocarbon-based refrigerants that have been prohibited because they destroy the ozone layer. In particular, the HC-based refrigerants do not significantly cause the greenhouse effect, whereby the use of the HC-based refrigerants is also intended to prevent global warming.
The compressor disclosed in Japanese Patent Publication No. Hei 3-45212 for example is known as a conventional compressor. This compressor is hereinafter referred to as the compressor of conventional example
1
.
FIG. 8
is a sectional plan view showing the inside of the compressor of the conventional example
1
.
A hermetic shell
1
is substantially cylindrical, and its diameter is nearly equal to its height. The upper face and the lower face of the hermetic shell
1
are sealed to make its inner space hermetic. A known compressing mechanism
2
, an electric motor
3
and a suction muffler
18
are accommodated inside the hermetic shell
1
.
The electric motor
3
is elastically supported by springs on three snubbers
13
disposed at the bottom of the inside of the hermetic shell
1
. Furthermore, the electric motor
3
is installed so that its shaft becomes substantially coaxial with the hermetic shell
1
. The electric motor
3
is electrically connected to an external power supply via a terminal connector
11
.
The compressing mechanism
2
comprises a cylinder
4
, a piston
5
and a crank portion
12
, and is disposed on the electric motor
3
. The crank portion
12
is connected to the upper end of the shaft of the electric motor
3
. The piston
5
reciprocates inside the cylinder
4
in the horizontal direction by virtue of the revolving force of the electric motor
3
transmitted via the crank portion
12
. The space inside the cylinder
4
through which the piston
5
reciprocates is closed by the front end of the piston
5
and a valve plate
6
thereby to form a compression chamber (not shown) for compressing a refrigerant gas. The valve plate
6
is provided with a suction valve for supplying the refrigerant gas into the compression chamber by suction, and a discharge valve for discharging the refrigerant gas from the compression chamber. These valves are not shown in
FIG. 8. A
cylinder head
7
is disposed outside the compression chamber, with the valve plate
6
held therebetween. A discharge pipe
10
is connected to the cylinder head
7
so that the refrigerant gas can be discharged from the inside of the cylinder head
7
to the outside of the hermetic shell
1
.
On the other hand, the suction muffler
18
is connected to the outside space
18
b
of the compression chamber. The inside of the suction muffler
18
is provided with a cavity communicating from the outside space
18
b
of the compression chamber to the suction inlet
18
a
of the suction muffler
18
. The suction inlet
18
a
is disposed opposite to the opening end
9
a
of a suction pipe
9
with a predetermined distance therebetween. The suction pipe
9
supplies the refrigerant gas by suction from the outside to the inside of the hermetic shell
1
.
The conventional hermetic compressor having the above-mentioned structure operates as described below thereby to raise the pressure of the refrigerant gas and to supply the high-pressure refrigerant gas to an external refrigeration cycle.
When the electric motor
3
is driven, the piston
5
is reciprocated inside the cylinder
4
by the crank portion
12
. The space inside the compression chamber is changed periodically in accordance with the reciprocation. The pressure of the refrigerant gas inside the compression chamber lowers while the space inside the compression chamber increases. At this time, the suction valve (not shown) is opened by the pressure difference between the pressure at the outside space
18
b
of the compression chamber and the pressure inside the compression chamber thereby to suck the refrigerant gas from inside the suction muffler
18
. On the other hand, the pressure of the refrigerant gas inside the compression chamber rises while the space inside the compression chamber decreases. At this time, the discharge valve (not shown) is opened by the pressure difference between the pressure inside the cylinder head
7
and the pressure inside the compression chamber, whereby the high-pressure refrigerant gas is discharged from the compression chamber into the cylinder head
7
. The high-pressure refrigerant gas inside the cylinder head
7
passes through the discharge pipe
10
and is discharged to the high-pressure side of the refrigeration cycle outside the hermetic shell
1
. The high pressure of the refrigerant gas is lowered in the refrigeration cycle. The refrigerant gas flowing from the low-pressure side of the refrigeration cycle passes through the suction pipe
9
and is supplied from the opening end
9
a
thereof to the hermetic shell
1
. The refrigerant gas supplied from the opening end
9
a
almost directly enters the suction inlet
18
a
of the suction muffler
18
. By periodically repeating the above-mentioned operation, the compressor of the conventional example
1
continuously supplies the high-pressure refrigerant gas to the refrigeration cycle.
The inner space in the hermetic shell
1
is sealed from outside. Therefore, noise caused by the electric motor
3
, the compressing mechanism
2
, the refrigerant gas sucked into the compression chamber and the like is unlikely to leak outside. Furthermore, the hermetic shell
1
prevents lubrication oil circulating through the various portions of the electric motor
3
and the compressing mechanism
2
from scattering outside. In addition, the hermetic shell
1
stores the lubrication oil at the bottom of its inner space to prevent them from leaking outside.
The suction muffler
18
serves to attenuate noise caused by a high-speed refrigerant gas flow sucked into the compression chamber. The refrigerant gas supplied into the suction muffler
18
advances through the cavity inside the suction muffler
18
, and is sucked from the outside space
18
b
of the compression chamber inside the cylinder
4
into the compression chamber. The shape of the cavity inside the suction muffler
18
is devised so as to sufficiently decrease the speed of the refrigerant gas flow while the refrigerant gas passes. For example, the suction muffler
18
may have partition walls (not shown in
FIG. 8
) so that the cavity inside the suction muffler
18
is partitioned into several chambers by the partition walls. In this case, the refrigerant gas flow snakes through the chambers inside the suction muffler
18
in sequence, whereby the speed of the flow is lowered. This lowers the level of the noise caused by the refrigerant gas flow in the vicinity of the outside space
18
b
of the compression chamber.
As described below, the suction muffler
18
also operates to separate mist-like lubrication oil included in the refrigeran
Freay Charles G.
Gray Michael K.
Matsushita Refrigeration Company
Sheridan & Ross P.C.
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