Pumps – Motor driven – Resiliently mounted pump or motor
Reexamination Certificate
1999-08-05
2001-04-03
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Resiliently mounted pump or motor
Reexamination Certificate
active
06210130
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a rotary compressor having a piston integrated with a blade, a refrigerating cycle of a refrigerating apparatus, an air conditioning apparatus, or the like using the compressor, and a refrigerator using the compressor.
2. Description of the Conventional Art
FIGS. 5 and 6
show a conventional rolling piston type rotary compressor (2-cylinder rotary compressor in the example) disclosed in, for example, Patent Publication No. 2502756.
FIG. 5
is a longitudinal cross section of the rotary compressor and shows a refrigerating cycle.
FIG. 6
is a transverse cross section of a compression mechanism portion of the rotary compressor. The description will be given hereinafter with reference to
FIGS. 5 and 6
. The conventional rotary compressor comprises an electric motor portion
50
having a stator
1
and a rotor
2
and a compression mechanism portion
60
which is driven by the electric motor portion
50
and has a frame
19
, a cylinder
5
having a cylinder chamber
4
to which a suction port
3
and a discharge port (not shown) are opened, a partition panel
34
for partitioning the cylinder into two chambers, a cylinder head
20
, a piston
8
rotatably fit on an eccentric shaft portion
7
of a driving shaft
6
and disposed in the cylinder
5
, a vane
11
for partitioning the cylinder chamber
4
into a low pressure chamber
9
communicating with the suction port
3
and a high-pressure chamber
10
communicating with the discharge port (not shown), a vane spring
12
for urging the vane
11
against the piston side so that the valve
11
is not to be apart from the piston
8
, and the driving shaft
6
. The electric motor portion
50
and the compression mechanism portion
60
are directly mounted in a hermetic vessel
13
in which a discharge pressure atmosphere or a suction pressure atmosphere is kept, by means of welding, shrinkage fitting, or the like.
FIG. 5
shows the case of using the discharge pressure atmosphere. The operation is performed in such a manner that the piston
8
revolves along the inner wall of the cylinder chamber
4
according to the rotation of the driving shaft
6
, a compressible fluid such as a refrigerant gas sucked from the suction port
3
is compressed in association with the revolution, and the fluid is discharged from the discharge port (not shown).
FIG. 7
is a longitudinal cross section of a conventional blade-integrated piston type rotary compressor disclosed in, for example, Japanese Unexamined Patent Publication No. 10-047278 and
FIG. 8
is a transverse cross section of a compression mechanism portion of the rotary compressor. In
FIGS. 7 and 8
, the compressor is comprised of an electric motor portion
50
having a stator
1
and a rotor
2
and a compression mechanism portion
60
driven by the electronic motor portion
50
. The electric motor portion
50
and the compression mechanism portion
60
are housed in a hermetic vessel
13
.
The compression mechanism portion
60
comprises a frame
19
, a cylinder
5
having a cylinder chamber
4
to which a suction port
3
and a discharge port
14
are opened, a cylinder head
20
, a piston
15
a
which is rotatably fit on an eccentric shaft portion
7
of a driving shaft
6
and disposed in the cylinder
5
, a blade
15
b
provided integrally with the piston
15
a
, for partitioning the cylinder chamber
4
into a low pressure chamber
9
communicating with the suction port
3
and a high pressure chamber
10
communicating with the discharge port
14
, a guide
17
which is rotatably fit in a cylindrical bore
16
formed in the cylinder
5
and slidably and swingably support the blade
15
b
and a driving shaft
6
.
By the rotation of the driving shaft
6
, the piston
15
a
revolves along the inner wall of the cylinder chamber
4
so as to swing as a fulcrum via the blade
15
b
on a rotation center
18
of the guide
17
, the compressible fluid such as refrigerant gas sucked from the suction port
3
is compressed every revolution, and the fluid is discharged via the discharge port
14
.
A structure similar to the blade-integrated piston type rotary compressor in which the piston and the blade are integrally formed and piston revolves eccentrically in the cylinder with aid of swinging motion is disclosed in FIG. 373 in page B5-159 and explanation for it in “Mechanical Engineer's Handbook” (issued by The Japan Society of Mechanical Engineers, Apr. 15, 1987).
In the conventional blade-integrated piston type rotary compressor, the electric motor portion
50
and the compression mechanism portion
60
are fixed in the hermetic vessel
13
by means of shrinkage fitting, welding, or the like and the discharge pressure atmosphere is kept in the hermetic vessel
13
.
In the conventional rolling piston type rotary compressor, as described above, the compression mechanism portion comprises the cylinder
5
, the piston
8
, the vane
11
, and the vane spring
12
. In order to partition the cylinder space into the low pressure chamber
9
communicating with the suction port
3
and the high pressure chamber
10
communicating with the discharge port
14
by the piston
8
and the vane
11
, it is necessary to make the tip of the vane
11
and the peripheral surface of the piston
8
always come into contact with each other with a right force. When the discharge pressure atmosphere is kept in the hermetic vessel
13
, a force by the differential pressure between the compression chambers
9
and
10
and the hermetic vessel
13
acts in the direction of urging the vane
11
against the piston
8
, so that the vane
11
can be pressed against the piston
8
by using the differential pressure. It is therefore sufficient to set the pressing force of the vane spring
12
to a smaller value by taking use of the differential pressure into account. In this case, in the compressor just before starting, a pressure is in a balanced state. Since the vane
11
is pressed against the piston
8
with a force which is smaller than the pressing force necessary in a steady operation by an amount of the differential pressure, an excessive load is not applied on the piston
8
and stable starting can be performed by a motor having the minimum starting torque.
On the contrary, during an off period of an ON/OFF operation performed by, for example, a compressor for refrigerator, the high-temperature high-pressure gas refrigerant in the hermetic vessel
13
is leaks from each of a contact surface
21
between the cylinder
5
and a frame
19
, a contact surface
23
between the cylinder
5
and a cylinder head
20
, and a contact surface
35
between the cylinder
5
and the partition panel
34
to the low pressure chamber
9
and a suction pipe
24
due to the pressure difference since the suction pressure is kept in a portion of the suction pipe
24
, the suction port
3
and the low pressure chamber
9
in the cylinder
5
and the other portion in the hermetic vessel
13
is filled with the discharge pressure atmosphere. The leaking gas flows back from the suction pipe
24
to an evaporator
36
and a temperature rise tends to be caused in a condenser of a refrigerator or the like. In order to prevent this, a check valve or the like has to be installed between the suction pipe
24
and the evaporator
36
, so that a problem of increased cost arises.
On the other hand, in case of using the structure such that the suction pressure atmosphere is kept in the hermetic vessel, the discharge pressure is kept in a portion of the high pressure chamber, the discharge portion, and the discharge pipe in the hermetic vessel and the other portion of the hermetic vessel is filled with the suction pressure atmosphere. A discharge valve provided on the discharge pipe side of the discharge port, however, plays the role of a check valve and separates the high-temperature high-pressure gas from the other. A leakage into the suction pressure portion does not occur during the off period of the ON/OFF operation and a gas does not flo
Gunjima Munehisa
Ishii Minoru
Kakuda Masayuki
Kawaguchi Susumu
Ogawa Yoshihide
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Rodriguez W
Thorpe Timothy S.
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