Rotary compressor

Details Rotary compressor Rotary compressor

2002-01-14

2003-07-15

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

With relatively movable partition member

C418S178000, C418S179000

Reexamination Certificate

active

06592347

ABSTRACT:

BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to a rotary compressor which uses carbonic acid gas as a refrigerant and uses polyalkylene glycol or polyalfa olefin as a lubricant or mineral oil as base oil, and more particularly to a structure of a roller and a vane which prevents abnormal abrasion of the roller and vane and is suitable for providing a reliable rotary compressor.
(ii) Description of the Related Art
A compressor used in a refrigerator, an automatic vending machine, a compressor for a showcase or an air conditioner for home/business use has been conventionally utilizing a large amount of dichlorodifluoromethane (R12) or monochlorodifluoromethane (R22) as a refrigerant. Such R12 or R22 is a target of control of CFC's because it has a problem that it destroys an ozone layer due to ozone crack potential when it is discharged into air and reaches the ozone layer in the upper air above the earth. The destruction of the ozone layer is provoked by a chloric group (C1) in the refrigerant. Thus, a refrigerant containing no chloric group, for example, an HFC-based refrigerant such as R32, R125 or R134a, a hydrocarbon group refrigerant such as propane or butane, or a natural refrigerant such as carbonic acid gas or ammonia is considered as an alternative refrigerant.
FIG. 1
is a view showing a cross-sectional structure of a two-cylinder type rotary compressor to which the present invention is applied.
FIG. 2
is a cross-sectional explanatory view showing the relationship between a cylinder, a roller, a vane and others.
FIG. 3
is an explanatory view of the vane. The rotary compressor denoted by reference numeral
1
as a whole includes a cylindrical closed container
10
, an electric motor
20
and a compressor
30
accommodated in the closed container
10
. The electric motor
20
has a stator
22
and a rotor
24
fixed on the inner wall portion of the closed container
10
, and a rotary shaft
25
attached at the center of the rotor
24
is rotatably supported by two plates
33
and
34
which close opening portions of cylinders
31
and
32
. A crank portion
26
which is eccentrically provided is formed at a part of the rotary shaft
25
. The cylinders
31
and
32
are provided between the two plates
33
and
34
. The cylinders
31
and
32
(description will be mainly given as to the cylinder
32
hereinafter) have an axis line which is the same as that of a rotary shaft
25
. An inlet
23
and an outlet
35
for the refrigerant are provided to the circumferential wall portion of the cylinder
32
.
A ring-like roller
38
is provided in the cylinder
32
, and the inner peripheral surface
38
B of the roller
38
comes into contact with the outer peripheral surface
26
A of the crank portion
26
. The outer peripheral surface
38
A of the roller
38
comes into contact with the inner peripheral surface
32
B of the cylinder
32
. A vane
40
is provided to the cylinder
32
so as to be capable of sliding, and an end of the vane
40
comes into contact with the outer peripheral surface
38
A of the roller
38
. When impetus is given to the vane
40
toward the roller
38
and the compressed refrigerant is led to the back surface of the vane
40
, sealing between the end of the vane and the roller
38
is secured. A compression chamber
50
is formed by being surrounded by the vane
40
, the roller
38
, the cylinder
32
and the plate
34
which closes the cylinder
32
and others. In the rotary compressor
1
, for example, polyol ester as a lubricant or polyvinyl ether or the like as base oil is used.
Thus, when the rotary shaft
25
rotates in the counterclockwise direction in
FIG. 2
, the roller
38
also eccentrically rotates in the cylinder
32
, and the coolant gas sucked from the inlet
23
is compressed and discharged from the outlet
35
. In the suction-compression-discharge stroke, pressing force Fv is generated at a contact portion between the roller
38
and the vane
40
.
Conventionally, a contact surface
40
A at the end of the vane
40
with respect to the outer peripheral surface
38
A of the roller
38
is formed into a circular shape having a radius of curvature Rv. This radius of curvature Rv has a value which is substantially equal to a width dimension T of the vane
40
and is approximately {fraction (1/10)} to ⅓ with respect to a radius dimension of the roller
38
. Further, as a material of the roller
38
, one obtained by hardening cast iron or alloy cast iron is mainly used. Also, as a material of the vane
40
, stainless steel, tool steel or one obtained by applying surface finishing such as nitriding treatment to such a material is mainly used. In particular, it is general to give the high hardness and toughness to the vane material.
As shown in
FIG. 4
, the contact state between the roller
38
and the vane
40
can be substituted by a problem of contact between the cylinders having different curvatures. In such a state, when the two elastic substances of the roller
38
and the vane
40
are pressed against each other by the pressing force Fv of the vane
40
, they generally have the surface contact instead of the point or line contact. A length of the elastic contact surface d at that moment can be calculated by the expression (7), and the Hertz stress Pmax (kgf/cm
2
) represented by the following expression (9) is generated at the contact portion (Hertz theory of elastic contact).
P
max=4
/&pgr;·Fv/L/d
  Expression (9)
(Fv, L and d in the expression (9) are equal to those in the expression (7))
When the surface contact is provided and the Hertz stress is increased in this manner, nitriding treatment for improving the abrasion resistance or surface treatment such as ion coating of CrN is performed to the vane of the rotary compressor which uses the refrigerant including no chlorine in its molecules and employs polyol ether as a lubricant or polyvinyl ether as base oil. However, there are problems that nitriding treatment does not provide the sufficient proof strength, ion coating of CrN may lead to exfoliation of a coating layer and the production cost is increased.
SUMMARY OF THE INVENTION
In order to solve the above-described problems in the prior art, it is an object of the present, invention to provide a highly reliable rotary compressor which uses polyalkylene glycol as a lubricant or polyalfa olefin as base oil in a compressor utilizing carbon dioxide which is a natural refrigerant as a refrigerant, and which prevents abnormal abrasion of a roller and a vane.
As a result of attentive study in order to solve the problems, the radius of curvature of the contact surface at the end of the vane which comes into contact with the outer peripheral surface of the roller is changed, although it has a value substantially equal to the width dimension of the vane. In particular, in the rotary compressor using carbon dioxide which is a natural refrigerant as an alternative refrigerant, the radius of curvature is set larger than the width dimension of the vane in a range for assuring the sliding contact surface at a sliding contact portion of the vane and the roller, and polyalkylene glycol as a lubricant or polyalfa olefin or mineral oil as a lubricant is used. Consequently, the Hertz stress can be reduced, and the sliding distance is increased. Furthermore, the stress is dispersed, and a temperature at the sliding contact portion of the vane and the roller can be lowered. Therefore, the present inventor has found that it is possible to provide the highly reliable rotary compressor which has an advantage of sufficiently reducing abrasion of the outer peripheral surface of the roller or the vane by the inexpensive nitriding processing (NV nitriding, sulphonitriding, radial nitriding) without applying the expensive coating treatment to the vane and prevents abnormal abrasion of the roller and the vane, and has attained the present invention.
To achieve this aim, according to the present invention, there is provided a rotary compressor defined in claim
1
including a refrige

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