Refrigeration – Processes – Employing diverse materials or particular material in...
Reexamination Certificate
1999-03-11
2001-02-20
Doerrler, William (Department: 3744)
Refrigeration
Processes
Employing diverse materials or particular material in...
C252S067000
Reexamination Certificate
active
06189322
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a refrigerant-circulating system, and a refrigerant compressor and a refrigeration cycle such as a freezer or an air-conditioner, employing the refrigerant compressor. More particularly, it relates to a refrigerator oil composition which is suitable to alternative refrigerants a containing no chlorine from the aspect of the protection of the ozone layer and excellent in the compatibility with the refrigerant, the low temperature flowability, thermochemical stability, wear resistance, anti-seizing property and electrical insulation property, and a refrigerant compressor containing said composition, provided with machinery parts, electrical insulating materials or the like excellent in the chemical stability, wear resistance, anti-seizing property and electrical insulation property, and a refrigeration cycle employing this refrigerant compressor.
In recent years, from the viewpoint of protection of ozone layer, it has been regulated to limit the use of freon type refrigerants such as CFC or HCFC containing chlorine which have been employed for refrigerators, freezers, dehumidifiers and air-conditioners.
Under such circumstances, as an alternative refrigerant, hydrofluorocarbon (HFC) and hydrocarbon (HC) which contain no chlorine and have a low reactivity with ozone and a short term for decomposition in air, have been studied and practiced.
However, such alternative refrigerants containing no chlorine in the molecule all have a high polarity and show poor compatibility with conventional refrigerator oils such as a mineral oil or an alkylbenzene oil which have been used for refrigeration cycles of refrigerants containing chlorine Accordingly, developments of new refrigerator oils have been made.
FIG. 15
shows a refrigeration cycle used for conventional alternative refrigerants described in JP-A-8-240351. FIGS.
16
(
a
) and (
b
) are cross-sectional views of a general refrigerant compressor used for refrigeration cycles suitable for conventional alternative refrigerants. FIG.
16
(
a
) is a vertical cross-sectional view and FIG.
16
(
b
) is a cross-sectional view seen from the upper face of a cylinder.
Here,
101
is a refrigerant compressor,
102
is a closed container,
103
is an evaporator,
104
is a condenser, and
105
is an expansion mechanism such as an expansion valve or a capillary tube. A hydrated fluorocarbon (HFC) containing no chlorine is encapsulated in the circuit to form the refrigeration cycle.
In the closed container
102
of the refrigerant compressor
101
, an electrically driving element
106
and a compressing element
107
are contained and a refrigerator oil
180
is stored at the bottom. Further, the electrically driving element
106
comprises a stator
109
and a rotor
110
, and the stator
109
comprises a wiring portion
111
and a core portion
112
, and electric power is supplied from a hermetically sealed terminal
113
to the electrically driving element
106
through a lead wire. The compressing element
107
is composed of a main shaft
114
connected to the rotor
110
, a rolling piston
115
engaged with an eccentric part of the main shaft
114
, a cylinder
116
which defines a compression chamber, a main bearing
117
and a sub bearing
118
which close the side faces of the cylinder
116
and at the same time support the main shaft
114
, a vane
119
which is slidingly in contact with the outer periphery of the rolling piston
115
and partitions off the compression chamber into a high pressure part and a low pressure part, and a vane spring
120
.
The refrigerant compressor
101
is connected to the refrigeration cycle by means of an intake tube
121
and a discharge tube
122
.
Now, the operation of conventional refrigeration cycle will be described.
When the compressor is operated, the rotation force of the electrically driving element
106
is transferred to the compressing element
106
by means of the main shaft
114
connected to the rotor
110
, whereby the rolling piston
115
engaged with the eccentric portion of the main shaft
114
is eccentrically rotated in the cylinder
116
. The vane
119
which partitions off the cylinder
116
into a high pressure part and a low pressure part, is reciprocally moved while the terminal end of the vane
119
is being in contact with the outer periphery of the rolling piston
115
by the back pressure and the spring force of a vane spring
120
.
The refrigerant is introduced into the cylinder
116
through the intake tube
112
, and compressed by the eccentric rotation of the rolling piston
115
and discharged to the inside of the closed container
102
from the cylinder
116
, and then used to cool the electrically driving element
106
and introduced to the external refrigeration cycle through the discharge tube
122
.
The overheated refrigerant gas of a high pressure and a high temperature discharged from the refrigerant compressor
101
, undergoes heat exchange with the external air by means of the condenser
104
to remove the latent heat, whereby it becomes a refrigerant liquid of a high pressure and a high temperature. Then, the refrigerant becomes a saturated refrigerant liquid of a low pressure by the pressure reduction by means of the expansion mechanism
105
, and further undergoes heat exchange with the external air by means of the evaporator
103
to let the latent heat absorbed, whereby it becomes a refrigerant gas.
Here, the refrigerator oil
180
stored at the bottom of the closed container
102
of the refrigerant compressor
101
, is supplied from the lower end of the main shaft
114
, and used for lubrication of respective sliding parts of the compressing element
107
, and then major part thereof is returned to the bottom of the closed container
102
, but a part thereof is discharged to the external portion of the refrigerant compressor
101
through the discharge tube
122
along with the refrigerant gas and circulated in the refrigeration cycle, and returned to the refrigerant compressor
101
through the intake tube
121
again.
Accordingly, the refrigerator oil used for the refrigeration cycle is firstly demanded to have a high compatibility with the refrigerant within a wide temperature range of from a low temperature to a high temperature and be excellent in the low temperature flowability, since it is circulated along with the refrigerant.
Further, with conventional refrigerants containing chlorine such as chlorofluorocarbon (CFC) or hydrochlorofluorocarbon (HCFC), the chlorine molecules function as an extreme-pressure additive on the surface of sliding parts and show extremely good lubricating properties. Whereas, with alternative refrigerants containing no chlorine which do not destroy the ozone layer, such extreme-pressure effect of the refrigerants themselves can not be expected, whereby refrigerator oils used for such alternative refrigerants are required to have excellent wear resistance, anti-seizing property, thermal stability and chemical stability in order to lubricate the sliding parts at a high temperature and a high pressure.
Further, since the refrigerator oil is used for the electrically driving element
106
in the closed container
102
, whereby it is demanded to have excellent insulating properties as well.
JP-A-1-259093 discloses as a refrigerator oil suitable to a halogenated fluorocarbon (HFC) refrigerant, ones containing propylene glycol monoether (PAG) represented by the following formula (2), as a base oil.
wherein R is an alkyl group.
Further, JP-A-1-259094 discloses a diether type compound formed by etherifying the terminal end of propylene glycol. However, it is generally known that the PAG oil is poor in the electrical insulating properties, moisture absorptivity, wear resistance and anti-seizing property, and can not be practically used for a closed type refrigerant compressor.
JP-A-8-240351 discloses a refrigerator oil suitable for a hydrogenated fluorocarbon (HFC) refrigerant, containing as a base oil, an ester oil of aliphatic acid having at le
Ishihara Keisaku
Izawa Takeshi
Masuda Noboru
Miki Shinsuke
Nakao Hideto
Doerrler William
Jones Melvin
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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