Pumps – Motor driven – Resiliently mounted pump or motor
Reexamination Certificate
1999-11-18
2001-08-21
Tyler, Cheryl J. (Department: 3746)
Pumps
Motor driven
Resiliently mounted pump or motor
C417S902000
Reexamination Certificate
active
06276906
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a hermetic motor compressor for use in a refrigerator or the like and, in particular but not exclusively, to a hermetic motor compressor capable of reducing noise emission.
BACKGROUND ART
Recently, hermetic motor compressors (hereinafter referred to simply as compressors) with reduced vibration and reduced noise emission are demanded. Because conventional refrigerants have a tendency to cause ozone layer damage or global warming, the use of hydrocarbon refrigerants having an ozone damaging coefficient of zero and a global warming coefficient of zero is commenced to protect global environment.
FIG. 6
depicts a conventional compressor as disclosed in Japanese Patent Publication (examined) No. 1-47632, which includes a hermetically sealed casing
1
and an integrated structure
4
accommodated in the casing
1
. The integrated structure
4
is made up of a compression section
2
and a drive section
3
integrally formed with each other. The compression section
2
includes a cylinder
5
, a piston
6
reciprocally mounted in the cylinder
5
, a crankshaft
7
connected to a rotor
3
a
of the drive section
3
for rotation together therewith, and a connecting rod
8
for connecting the piston
6
to the crankshaft
7
to convert rotation of the crankshaft to a reciprocating motion of the piston
6
.
The casing
1
has a generally flat bottom wall
1
a
and a generally cylindrical side wall
1
b
unitarily formed with each other. A gas inlet tube
10
is welded to the side wall
1
b
, while a plurality of legs
11
are welded or secured to the bottom wall
1
a
. The integrated structure
4
is supported by a stay
12
welded to the inner surface of the side wall
1
b
, while the drive section
3
is electrically connected to a power source (not shown) via a hermetic terminal
13
hermetically welded to the side wall
1
b.
In the above-described construction, because the bottom wall
1
a
is generally flat, the plurality of legs
11
can be welded thereto with good workability. Also, because the side wall
1
b
is generally cylindrical and not spherical, the stay
12
can be welded thereto with good workability.
The casing
1
is, however, low in rigidity due to the generally flat shape of the bottom wall
1
a
and the generally cylindrical shape of the side wall
1
b
. Because of this, the casing
1
oscillates slightly and generates noise, or sound produced during operation of the integrated structure
4
accommodated therein leaks through the generally flat or cylindrical portion, thus increasing the noise.
Particularly, in applications where a hydrocarbon refrigerant such as, for example, isobutane is used for a compression refrigerant, the concentration of circulating refrigerant is reduced during cyclic operation of the compressor at the same condensation and evaporation temperatures as in the operation with the use of a conventional refrigerant (for example, CFCR12, HFCR134a or the like) including fluorine or chlorine. Accordingly, enlargement of the internal volume of the cylinder
5
is required, which in turn causes an increase in unbalanced mass, thus increasing vibration and generating noise.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide a hermetic motor compressor capable of reducing vibration and noise emission even if the unbalanced mass is increased which has been hitherto caused by enlargement of the internal volume of the cylinder.
DISCLOSURE OF THE INVENTION
In accomplishing the above and other objectives, the hermetic motor compressor according to the present invention includes a generally spherical casing having a generally spherical side wall and a first downwardly curved bottom wall, an integrated structure accommodated in the casing and having a compression section and a drive section integrally formed with each other, a plurality of supporting units for elastically supporting the integrated structure, and a plurality of legs secured to the first downwardly curved bottom wall and having the same shape as the downwardly curved bottom wall.
This construction is particularly useful when a hydrocarbon refrigerant is used. The reason for this is that the use of the hydrocarbon refrigerant requires enlargement of the internal volume of a cylinder, which in turn causes an increase in unbalanced mass, thus increasing noise. The noise can be considerably reduced by forming the casing into a generally spherical shape having no flat or cylindrical portions, because the generally spherical casing has a high rigidity. In addition, the legs secured to the bottom wall rigidify the casing and reduce noise.
The casing preferably has a second downwardly curved bottom wall having a radius of curvature different from that of the first downwardly curved bottom wall. The two downwardly curved bottom walls having different radii of curvature further rigidify the casing, thus reducing noise.
Advantageously, each of the plurality of supporting units includes a stay of substantially the same shape as the side wall. This stay increases the rigidity of the casing, thus reducing noise.
The stay preferably has a protruding portion integrally formed therewith, a ring-shaped elastic member through which the protruding portion extends, and a stopper mounted on the ring-shaped elastic member, with the protruding portion inserted into the stopper.
Because the ring-shaped elastic member acts as a cushioning member, vibration caused by the compression section and increased with the increase in unbalanced mass is not easily transmitted to the stay via the stopper, thus reducing noise during operation of the compressor.
The casing is generally of two-piece construction having two halves welded together. In this case, it is preferred that the side wall has a radius of curvature smaller than 100% of a radius of curvature of an opening of one of the two halves, while the first downwardly curved bottom wall has a radius of curvature smaller than 120% of the radius of curvature of the opening. It is also preferred that the second downwardly curved bottom wall has a radius of curvature smaller than 35% of the radius of curvature of the opening. The above limitations in radius of curvature are particularly effective in increasing the rigidity of the casing to reduce noise.
REFERENCES:
patent: 3187995 (1965-06-01), Kjeldsen
patent: 4427349 (1984-01-01), Elson
patent: 4478559 (1984-10-01), Andrione et al.
patent: 4990067 (1991-02-01), Sasano et al.
patent: 5554015 (1996-09-01), Dreiman et al.
patent: 6171077 (2001-01-01), Calciolari et al.
patent: 507091 A1 (1992-10-01), None
patent: 0 521 526 (1993-01-01), None
patent: 0 561 385 (1993-09-01), None
patent: 63-061795 (1988-03-01), None
patent: 1-47632 (1989-10-01), None
patent: 3-107581 A (1991-05-01), None
patent: 3-225084 A (1991-10-01), None
patent: 5-10266 (1993-01-01), None
Matsushita Refrigeration Company
Tyler Cheryl J.
Wenderoth , Lind & Ponack, L.L.P.
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