U.S. patent application number 17/256032 was filed with the patent office on 2021-04-29 for hermetic refrigerant compressor and refrigerator-freezer using the same.
This patent application is currently assigned to Panasonic Appliances Refrigeration Devices Singapore. The applicant listed for this patent is Panasonic Appliances Refrigeration Devices Singapore. Invention is credited to Hironari AKASHI, Masanobu GONDO, Hiroto HAYASHI, Terumasa IDE, Hirotaka KAWABATA, Akio YAGI.
Application Number | 20210123426 17/256032 |
Document ID | / |
Family ID | 1000005340132 |
Filed Date | 2021-04-29 |
United States Patent
Application |
20210123426 |
Kind Code |
A1 |
HAYASHI; Hiroto ; et
al. |
April 29, 2021 |
HERMETIC REFRIGERANT COMPRESSOR AND REFRIGERATOR-FREEZER USING THE
SAME
Abstract
A hermetic refrigerant compressor (100) includes a sealed
container (101) in which lubricating oil (103) having a kinematic
viscosity in a range of 1 to 9 mm.sup.2/S at 40.degree. C. is
stored, the lubricating oil (103) containing a sliding modifier
that is either sulfur or a sulfur-containing compound. A
compression element (107) includes a shaft part that is a crank
shaft (108). In a case where a sliding surface of a main shaft
(109) is a single sliding surface, a length of the single sliding
surface in an axial direction is a single sliding length L, whereas
in a case where the sliding surface is divided into a plurality of
sliding surfaces, a length of one of the sliding surfaces in the
axial direction, the one sliding surface having the least length in
the axial direction among the plurality of sliding surfaces, is the
single sliding length L, and a ratio L/D of the single sliding
length L to an external diameter D of the main shaft (109) is less
than or equal to 0.51.
Inventors: |
HAYASHI; Hiroto; (Kadoma
City, JP) ; KAWABATA; Hirotaka; (Kadoma City, JP)
; IDE; Terumasa; (Kadoma City, JP) ; AKASHI;
Hironari; (Kadoma City, JP) ; GONDO; Masanobu;
(Kadoma City, JP) ; YAGI; Akio; (Kadoma City,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Appliances Refrigeration Devices Singapore |
Singapore |
|
SG |
|
|
Assignee: |
Panasonic Appliances Refrigeration
Devices Singapore
Singapore
SG
|
Family ID: |
1000005340132 |
Appl. No.: |
17/256032 |
Filed: |
June 25, 2019 |
PCT Filed: |
June 25, 2019 |
PCT NO: |
PCT/JP2019/025141 |
371 Date: |
December 24, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 39/0253 20130101;
F04B 39/122 20130101; F04C 2210/26 20130101; F04B 39/0094
20130101 |
International
Class: |
F04B 39/02 20060101
F04B039/02; F04B 39/00 20060101 F04B039/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2018 |
JP |
2018-122489 |
Claims
1. A hermetic refrigerant compressor comprising a sealed container
in which lubricating oil having a kinematic viscosity in a range of
1 mm.sup.2/S to 9 mm.sup.2/S at 40.degree. C. is stored, the sealed
container accommodating an electric element and a compression
element, the compression element being driven by the electric
element and configured to compress a refrigerant, wherein the
compression element includes: a shaft part that is a crank shaft
including a main shaft and an eccentric shaft; and a bearing part
that pivotally supports the shaft part, the bearing part including
a main bearing and an eccentric bearing, the main bearing pivotally
supporting the main shaft, the eccentric bearing pivotally
supporting the eccentric shaft, the main shaft includes a sliding
surface that slides on the main bearing, the sliding surface being
either a single sliding surface or divided into a plurality of
sliding surfaces, in a case where the sliding surface is the single
sliding surface, a length of the single sliding surface in an axial
direction is a single sliding length L, whereas in a case where the
sliding surface is divided into the plurality of sliding surfaces,
a length of one of the sliding surfaces in the axial direction, the
one sliding surface having the least length in the axial direction
among the plurality of sliding surfaces, is the single sliding
length L, and a ratio L/D of the single sliding length L to an
external diameter D of the main shaft is less than or equal to
0.51, and the lubricating oil contains a sliding modifier that is
either sulfur or a sulfur-containing compound.
2. The hermetic refrigerant compressor according to claim 1,
wherein in the case where the sliding surface is divided into the
plurality of sliding surfaces, when a total of the lengths of the
plurality of sliding surfaces in the axial direction is a total
sliding length Lt, a ratio Lt/D of the total sliding length Lt to
the external diameter D is less than or equal to 1.26.
3. The hermetic refrigerant compressor according to claim 1,
wherein the ratio L/D is greater than or equal to 0.15.
4. The hermetic refrigerant compressor according to claim 2,
wherein the ratio Lt/D is greater than or equal to 0.3.
5. The hermetic refrigerant compressor according to claim 1,
wherein a content of the sliding modifier in the lubricating oil in
terms of an atomic weight of sulfur is greater than or equal to 100
ppm.
6. The hermetic refrigerant compressor according to claim 1,
wherein the lubricating oil further contains a phosphorus-based
extreme-pressure additive.
7. The hermetic refrigerant compressor according to claim 1,
wherein the electric element is inverter-driven at a plurality of
operating frequencies.
8. A refrigerator-freezer comprising a refrigerant circuit
including: the hermetic refrigerant compressor according to claim
1; a radiator; a decompressor; and a heat absorber, wherein in the
refrigerant circuit, the hermetic refrigerant compressor, the
radiator, the decompressor, and the heat absorber are connected by
piping in an annular manner.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hermetic refrigerant
compressor for use in, for example, a refrigerator or an air
conditioner and also to a refrigerator-freezer using the hermetic
refrigerant compressor.
BACKGROUND ART
[0002] In recent years, from the viewpoint of global environment
conservation, the development of a high-efficient hermetic
refrigerant compressor that uses less fossil fuels has been
conducted. For example, in order to realize high efficiency, it has
been proposed to form various films on sliding surfaces of slide
members included in the hermetic refrigerant compressor, and to use
lubricating oil having a reduced viscosity.
[0003] The hermetic refrigerant compressor includes a sealed
container in which the lubricating oil is stored. The sealed
container also accommodates an electric element and a compression
element. The compression element includes, as the slide members,
for example, a crank shaft, a piston, and a connecting rod serving
as a coupler. A main shaft of the crank shaft and a main bearing,
the piston and a bore, a piston pin and the connecting rod, and an
eccentric shaft of the crank shaft and the connecting rod, etc.,
form slide parts with each other.
[0004] For example, Patent Literature 1 discloses a reciprocating
compressor (hermetic refrigerant compressor) using lubricating oil
having a low viscosity. The reciprocating compressor is configured
such that, among the slide members, the piston and the connecting
rod are each made of a ferrous sintered material and are
steam-treated, and then a steam layer is removed from the surface
of the piston by cutting, whereas the connecting rod is subjected
to nitriding after being steam-treated. In Patent Literature 1, the
lubricating oil used in the reciprocating compressor thus
configured has a kinematic viscosity in the range of 3 mm.sup.2/S
to 10 mm.sup.2/S at 40.degree. C.
[0005] If the lubricating oil has a low viscosity, an oil film is
not easily formed. In this respect, in the hermetic refrigerant
compressor disclosed by Patent Literature 1, the surfaces of the
slide members forming the slide parts are subjected to special
treatment so that even with the use of the lubricating oil having a
low viscosity, wear or seizing of the piston and the connecting rod
will be prevented.
CITATION LIST
Patent Literature
[0006] PTL 1: Japanese Laid-Open Patent Application Publication No.
2011-021530
SUMMARY OF INVENTION
Technical Problem
[0007] Incidentally, the crank shaft included in a hermetic
refrigerant compressor constitutes a shaft part of the compression
element driven by the electric element, and the shaft part is
pivotally supported in a rotatable manner by a bearing part. By
reducing the sliding area of each of the shaft part and the bearing
part (pivotally supporting part), further increased efficiency can
be obtained. However, reduction in the sliding area causes lowered
wear resistance.
[0008] The above-described reciprocating compressor (hermetic
refrigerant compressor) disclosed by Patent Literature 1 uses the
low-viscosity lubricating oil, which has a kinematic viscosity in
the range of 3 mm.sup.2/S to 10 mm.sup.2/S at 40.degree. C.
However, wear resistance to be improved in Patent Literature 1 is
the wear resistance of the piston and the connecting rod, and
unlike the crank shaft, the piston and the connecting rod are not
pivotally supported by the bearing part. Accordingly, in the case
of improving the wear resistance of the piston and the connecting
rod, unlike the case of the crank shaft, the sliding area of the
pivotally supporting part would not be reduced in order to achieve
high efficiency.
[0009] The present invention has been made in order to solve the
above-described problems. An object of the present invention is to
provide a hermetic refrigerant compressor that makes it possible to
achieve high reliability of the shaft part that is pivotally
supported by the bearing part even with the use of lubricating oil
having a reduced viscosity.
Solution to Problem
[0010] In order to solve the above-described problems, a hermetic
refrigerant compressor according to the present invention includes
a sealed container in which lubricating oil having a kinematic
viscosity in a range of 1 mm.sup.2/S to 9 mm.sup.2/S at 40.degree.
C. is stored, the sealed container accommodating an electric
element and a compression element, the compression element being
driven by the electric element and configured to compress a
refrigerant. The compression element includes: a shaft part that is
a crank shaft including a main shaft and an eccentric shaft; and a
bearing part that pivotally supports the shaft part, the bearing
part including a main bearing and an eccentric bearing, the main
bearing pivotally supporting the main shaft, the eccentric bearing
pivotally supporting the eccentric shaft. The main shaft includes a
sliding surface that slides on the main bearing, the sliding
surface being either a single sliding surface or divided into a
plurality of sliding surfaces. In a case where the sliding surface
is the single sliding surface, a length of the single sliding
surface in an axial direction is a single sliding length L, whereas
in a case where the sliding surface is divided into the plurality
of sliding surfaces, a length of one of the sliding surfaces in the
axial direction, the one sliding surface having the least length in
the axial direction among the plurality of sliding surfaces, is the
single sliding length L, and a ratio L/D of the single sliding
length L to an external diameter D of the main shaft is less than
or equal to 0.51. The lubricating oil contains a sliding modifier
that is either sulfur or a sulfur-containing compound.
[0011] According to the above configuration, the lubricating oil is
low-viscosity oil; the ratio L/D of the single sliding length L to
the external diameter D is less than or equal to 0.51 regardless of
whether the sliding surface of the main shaft is a single sliding
surface or a plurality of sliding surfaces; and the lubricating oil
contains the sulfur-based sliding modifier. Owing to these
features, even though the lubricating oil is low-viscosity oil and
the sliding area is reduced such that the ratio L/D is less than or
equal to 0.51, favorable wear resistance of the slide part can be
realized by the sulfur-based sliding modifier. Consequently, the
hermetic refrigerant compressor can be obtained, which makes it
possible to achieve high reliability of the shaft part, which is
pivotally supported by the bearing part, even with the use of the
lubricating oil having a reduced viscosity.
[0012] A refrigerator-freezer according to the present invention
includes a refrigerant circuit including: the hermetic refrigerant
compressor configured as above; a radiator; a decompressor; and a
heat absorber. In the refrigerant circuit, the hermetic refrigerant
compressor, the radiator, the decompressor, and the heat absorber
are connected by piping in an annular manner.
[0013] According to the above configuration, in the hermetic
refrigerant compressor, the low-viscosity lubricating oil is used;
the sliding area is reduced; and the shaft part has high
reliability. Since the refrigerator-freezer includes the hermetic
refrigerant compressor, which is highly efficient and highly
reliable, the power consumption of the refrigerator-freezer can be
reduced, and also, the refrigerator-freezer can be made highly
reliable.
[0014] The above and other objects, features, and advantages of the
present invention will more fully be apparent from the following
detailed description of preferred embodiments with accompanying
drawings.
Advantageous Effects of Invention
[0015] The present invention is configured as described above, and
has an advantage of being able to provide a hermetic refrigerant
compressor that makes it possible to achieve high reliability of
the shaft part, which is pivotally supported by the bearing part,
even with the use of the lubricating oil having a reduced
viscosity.
BRIEF DESCRIPTION OF DRAWINGS
[0016] FIG. 1 is a schematic sectional view showing one example of
the configuration of a refrigerant compressor according to an
embodiment of the present disclosure.
[0017] FIG. 2 is a schematic side view showing one example of the
configuration of a crank shaft included in the refrigerant
compressor shown in FIG. 1.
[0018] FIG. 3A is a schematic diagram showing one configuration
example in a case where a sliding surface of the crank shaft shown
in FIG. 2 is a single sliding surface; and FIG. 3B and FIG. 3C are
schematic diagrams each showing one configuration example in a case
where the sliding surface of the crank shaft shown in FIG. 2 is
divided into a plurality of sliding surfaces.
[0019] FIG. 4 is a schematic diagram showing one example of the
configuration of a refrigerator-freezer including the refrigerant
compressor shown in FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0020] A hermetic refrigerant compressor according to the present
disclosure includes a sealed container in which lubricating oil
having a kinematic viscosity in a range of 1 mm.sup.2/S to 9
mm.sup.2/S at 40.degree. C. is stored, the sealed container
accommodating an electric element and a compression element, the
compression element being driven by the electric element and
configured to compress a refrigerant. The compression element
includes: a shaft part that is a crank shaft including a main shaft
and an eccentric shaft; and a bearing part that pivotally supports
the shaft part, the bearing part including a main bearing and an
eccentric bearing, the main bearing pivotally supporting the main
shaft, the eccentric bearing pivotally supporting the eccentric
shaft. The main shaft includes a sliding surface that slides on the
main bearing, the sliding surface being either a single sliding
surface or divided into a plurality of sliding surfaces. In a case
where the sliding surface is the single sliding surface, a length
of the single sliding surface in an axial direction is a single
sliding length L, whereas in a case where the sliding surface is
divided into the plurality of sliding surfaces, a length of one of
the sliding surfaces in the axial direction, the one sliding
surface having the least length in the axial direction among the
plurality of sliding surfaces, is the single sliding length L, and
a ratio L/D of the single sliding length L to an external diameter
D of the main shaft is less than or equal to 0.51. The lubricating
oil contains a sliding modifier that is either sulfur or a
sulfur-containing compound.
[0021] According to the above configuration, the lubricating oil is
low-viscosity oil; the ratio L/D of the single sliding length L to
the external diameter D is less than or equal to 0.51 regardless of
whether the sliding surface of the main shaft is a single sliding
surface or a plurality of sliding surfaces; and the lubricating oil
contains the sulfur-based sliding modifier. Owing to these
features, even though the lubricating oil is low-viscosity oil and
the sliding area is reduced such that the ratio L/D is less than or
equal to 0.51, favorable wear resistance of the slide part can be
realized by the sulfur-based sliding modifier. Consequently, the
hermetic refrigerant compressor can be obtained, which makes it
possible to achieve high reliability of the shaft part, which is
pivotally supported by the bearing part, even with the use of the
lubricating oil having a reduced viscosity.
[0022] In the hermetic refrigerant compressor configured as above,
in the case where the sliding surface is divided into the plurality
of sliding surfaces, when a total of the lengths of the plurality
of sliding surfaces in the axial direction is a total sliding
length Lt, a ratio Lt/D of the total sliding length Lt to the
external diameter D may be less than or equal to 1.26.
[0023] According to the above configuration, in the case where the
sliding surface is divided into the plurality of sliding surfaces,
the sliding area is reduced such that not only is the ratio L/D
less than or equal to 0.51, but also the ratio Lt/D of the total
sliding length Lt to the external diameter D is less than or equal
to 1.26. Accordingly, in a state where the low-viscosity
lubricating oil is used and the sliding area is reduced, the wear
resistance of the slide part derived from the sulfur-based sliding
modifier can be more improved.
[0024] In the hermetic refrigerant compressor configured as above,
the ratio L/D may be greater than or equal to 0.15.
[0025] According to the above configuration, if the ratio L/D is
greater than or equal to 0.15, the sliding area is not reduced
excessively. For this reason, in a state where the low-viscosity
lubricating oil is used and the sliding area is reduced, suitable
wear resistance of the slide part can be realized by the
sulfur-based sliding modifier.
[0026] In the hermetic refrigerant compressor configured as above,
the ratio Lt/D may be greater than or equal to 0.3.
[0027] According to the above configuration, if the ratio Lt/D is
greater than or equal to 0.3, the sliding area is not reduced
excessively even in the case where the sliding surface is divided
into the plurality of sliding surfaces. For this reason, in a state
where the low-viscosity lubricating oil is used and the sliding
area is reduced, suitable wear resistance of the slide part can be
realized by the sulfur-based sliding modifier.
[0028] In the hermetic refrigerant compressor configured as above,
a content of the sliding modifier in the lubricating oil in terms
of an atomic weight of sulfur may be greater than or equal to 100
ppm.
[0029] According to the above configuration, the sulfur-based
sliding modifier is added to the lubricating oil, such that the
sliding modifier content therein in terms of the atomic weight of
sulfur is greater than or equal to 100 ppm. Accordingly, in a state
where the low-viscosity lubricating oil is used and the sliding
area is reduced, suitable wear resistance of the slide part derived
from the sulfur-based sliding modifier can be realized.
[0030] In the hermetic refrigerant compressor configured as above,
the lubricating oil may further contain a phosphorus-based
extreme-pressure additive.
[0031] According to the above configuration, in addition to the
sulfur-based sliding modifier, the phosphorus-based
extreme-pressure additive is added to the lubricating oil, and
thereby, for example, wear of the slide part can be reduced
favorably.
[0032] In the hermetic refrigerant compressor configured as above,
the electric element may be inverter-driven at a plurality of
operating frequencies.
[0033] According to the above configuration, in the case where the
electric element is inverter-driven, regardless of whether
low-speed operation is being performed or high-speed operation is
being performed, the wear resistance of the slide part derived from
the sulfur-based sliding modifier can be realized. Therefore, the
reliability of the hermetic refrigerant compressor can be
improved.
[0034] A refrigerator-freezer according to the present disclosure
includes a refrigerant circuit including: the hermetic refrigerant
compressor configured as above; a radiator; a decompressor; and a
heat absorber. In the refrigerant circuit, the hermetic refrigerant
compressor, the radiator, the decompressor, and the heat absorber
are connected by piping in an annular manner.
[0035] According to the above configuration, in the hermetic
refrigerant compressor, the low-viscosity lubricating oil is used;
the sliding area is reduced; and the shaft part has high
reliability. Since the refrigerator-freezer includes the hermetic
refrigerant compressor, which is highly efficient and highly
reliable, the power consumption of the refrigerator-freezer can be
reduced, and also, the refrigerator-freezer can be made highly
reliable.
[0036] Hereinafter, representative embodiments of the present
invention are described with reference to the drawings. In the
drawings, the same or corresponding elements are denoted by the
same reference signs, and repeating the same descriptions is
avoided below.
Embodiment 1
[0037] [Configuration of Refrigerant Compressor]
[0038] First, a representative configuration example of a hermetic
refrigerant compressor according to Embodiment 1 of the present
disclosure is specifically described with reference to FIG. 1 and
FIG. 2. FIG. 1 is a schematic sectional view showing one example of
the configuration of a hermetic refrigerant compressor 100
according to Embodiment 1 of the present disclosure (hereinafter,
the hermetic refrigerant compressor 100 may be simply referred to
as "refrigerant compressor 100"). FIG. 2 is a schematic side view
showing one example of the configuration of a crank shaft 108,
which is a shaft part included in the refrigerant compressor
100.
[0039] As shown in FIG. 1, the refrigerant compressor 100 includes
a sealed container 101 filled with a refrigerant that is, for
example, R600a. Mineral oil is stored in the bottom of the sealed
container 101 as lubricating oil 103. In the present disclosure,
the lubricating oil 103 has a kinematic viscosity in the range of 1
mm.sup.2/S to 9 mm.sup.2/S at 40.degree. C. It should be noted
that, in Embodiment 1, although the lubricating oil 103 is
low-viscosity mineral oil, the lubricating oil 103 is not thus
limited as described below. Also, as described below, the
lubricating oil 103 contains at least a sulfur-based sliding
modifier (or a wear inhibitor). The lubricating oil 103 may further
contain an extreme-pressure additive.
[0040] The sealed container 101 also accommodates an electric
element 106 and a compression element 107. The electric element 106
is constituted by a stator 104 and a rotor 105. The compression
element 107 is a reciprocating element driven by the electric
element 106. The compression element 107 includes, for example, the
crank shaft 108, a cylinder block 112, and a piston 120.
[0041] The crank shaft 108 is constituted by, also as shown in FIG.
2, a main shaft 109 and an eccentric shaft 110. The rotor 105 is
fixed to the main shaft 109 by press-fitting. The eccentric shaft
110 is formed such that it is eccentric with the main shaft 109. In
Embodiment 1, the outer peripheral surface of the main shaft 109 of
the crank shaft 108 includes a first sliding surface 111a, a second
sliding surface 111b, and a non-sliding outer peripheral surface
111c. In addition, an unshown oil-feeding pump is provided at the
lower end of the crank shaft 108.
[0042] In Embodiment 1, for example, the cylinder block 112 is made
of cast iron. The cylinder block 112 forms a substantially
cylindrical bore 113, and includes a main bearing 114, which
pivotally supports the main shaft 109 of the crank shaft 108. The
inner peripheral surface of the main bearing 114 is slidably in
contact with the first sliding surface 111a and the second sliding
surface 111b of the outer peripheral surface of the main shaft 109,
but is not in contact with the non-sliding outer peripheral surface
111c.
[0043] It should be noted that, as shown in FIG. 1, the eccentric
shaft 110 of the crank shaft 108 is positioned in the upper side of
the refrigerant compressor 100, whereas the main shaft 109 of the
crank shaft 108 is positioned in the lower side of the refrigerant
compressor 100. Therefore, this upper-lower positional relationship
(direction) is utilized when describing positions on the crank
shaft 108 herein. For example, the upper end of the eccentric shaft
110 faces the inner upper surface of the sealed container 101, and
the lower end of the eccentric shaft 110 is connected to the main
shaft 109. The upper end of the main shaft 109 is connected to the
eccentric shaft 110, and the lower end of the main shaft 109 faces
the inner lower surface of the sealed container 101. The lower end
portion of the main shaft 109 is immersed in the lubricating oil
103.
[0044] In the present disclosure, the term "sliding surface" means
a surface that is a portion of the outer peripheral surface of the
shaft part, the portion being slidably in contact with the inner
peripheral surface of a bearing part. The non-sliding outer
peripheral surface 111c constitutes a portion of the outer
peripheral surface of the main shaft 109. However, unlike the first
sliding surface 111a and the second sliding surface 111b, the
non-sliding outer peripheral surface 111c is a surface that is
recessed (or receding) from the sliding surfaces (the first sliding
surface 111a and the second sliding surface 111b), such that the
non-sliding outer peripheral surface 111c is not in contact with
the inner peripheral surface of the bearing part. In other words,
the portions of the main shaft 109 serving as the sliding surfaces
are greater in diameter or radius than the portion of the main
shaft 109 serving as the non-sliding outer peripheral surface
111c.
[0045] The piston 120 is inserted in the bore 113 in a reciprocable
manner, and thereby a compression chamber 121 is formed. A piston
pin 115 having, for example, a substantially cylindrical shape is
disposed parallel to the eccentric shaft 110. The piston pin 115 is
locked to a piston pin hole formed in the piston 120 in a
non-rotatable manner.
[0046] A coupler 117 is, for example, constituted by an aluminum
casting product. The coupler 117 includes an eccentric bearing 119,
which pivotally supports the eccentric shaft 110, and the coupler
117 couples the eccentric shaft 110 and the piston 120 via the
piston pin 115. The end face of the bore 113 is sealed by a valve
plate 122.
[0047] It should be noted that, in the present disclosure, the main
shaft 109 and the eccentric shaft 110 included in the crank shaft
108 are collectively referred to as the "shaft part". Also, the
main bearing 114 of the cylinder block 112, which pivotally
supports the main shaft 109, and the eccentric bearing 119 of the
coupler 117, which pivotally supports the eccentric shaft 110, are
collectively referred to as the "bearing part".
[0048] A cylinder head 123 forms an unshown high-pressure chamber,
and is fixed to the valve plate 122 at the opposite side to the
bore 113. An unshown suction tube is fixed to the sealed container
101, and also connected to the low-pressure side (not shown) of a
refrigeration cycle, such that the suction tube leads the
refrigerant gas into the sealed container 101. A suction muffler
124 is held in a sandwiched manner between the valve plate 122 and
the cylinder head 123.
[0049] The main shaft 109 of the crank shaft 108 and the main
bearing 114, the piston 120 and the bore 113, the piston pin 115
and a connecting rod of the coupler 117, and the eccentric shaft
110 of the crank shaft 108 and the eccentric bearing 119 of the
coupler 117, etc., form slide parts with each other.
[0050] In the refrigerant compressor 100 thus configured, first,
electric power is supplied from an unshown commercial power supply
to the electric element 106 to cause the rotor 105 of the electric
element 106 to rotate. The rotor 105 causes the crank shaft 108 to
rotate, and eccentric motion of the eccentric shaft 110 from the
coupler 117 drives the piston 120 via the piston pin 115. The
piston 120 makes reciprocating motion in the bore 113, sucks the
refrigerant gas that has been led into the sealed container 101
through the suction tube from the suction muffler 124, and
compresses the sucked refrigerant gas in the compression chamber
121.
[0051] It should be noted that a specific method adopted herein for
driving the refrigerant compressor 100 is not particularly limited.
For example, the refrigerant compressor 100 may be driven by simple
on-off control, or may be inverter-driven at a plurality of
operating frequencies. In the case where the refrigerant compressor
100 is inverter-driven, in order to optimize the operation control
of the refrigerant compressor 100, low-speed operation or
high-speed operation is performed. When the low-speed operation is
performed, the amount of oil fed to each slide part decreases,
whereas when the high-speed operation is performed, the rotation
speed of the electric element 106 increases. Here, in the
refrigerant compressor 100, the wear resistance of the main shaft
109 can be improved as described below. Consequently, the
reliability of the refrigerant compressor 100 can be improved.
[0052] Among the plurality of slide parts included in the
refrigerant compressor 100, the main shaft 109 of the crank shaft
108 is rotatably fitted to the main bearing 114, and thereby a
slide part is formed. Therefore, for the sake of convenience of the
description, the slide part thus formed by the main shaft 109 and
the main bearing 114 is referred to as a "main shaft slide part".
Similarly, the eccentric shaft 110 of the crank shaft 108 is
rotatably fitted to the eccentric bearing 119, and thereby a slide
part is formed. Therefore, for the sake of convenience of the
description, the slide part thus formed by the eccentric shaft 110
and the eccentric bearing 119 is referred to as an "eccentric shaft
slide part". Also, the "main shaft slide part" and the "eccentric
shaft slide part" are collectively referred to as a "shaft slide
part".
[0053] In accordance with the rotation of the crank shaft 108, the
oil-feeding pump feeds the lubricating oil 103 to each slide part,
and thereby each slide part is lubricated. It should be noted that
the lubricating oil 103 serves to seal between the piston 120 and
the bore 113.
[0054] [Configuration of Shaft Slide Part]
[0055] Next, one example of a specific configuration of the shaft
slide part according to the present disclosure is specifically
described with reference to FIG. 3A to FIG. 3C. FIG. 3A is a
schematic diagram showing one configuration example in a case where
the sliding surface of the crank shaft 108 shown in FIG. 2 is a
single sliding surface. FIG. 3B and FIG. 3C are schematic diagrams
each showing one configuration example in a case where the sliding
surface of the crank shaft 108 shown in FIG. 2 is divided into a
plurality of sliding surfaces.
[0056] In the example shown in FIG. 2, the main shaft 109 of the
crank shaft 108, which is the shaft part, is configured to include
the first sliding surface 111a and the second sliding surface 111b.
In other words, the sliding surface of the main shaft 109 is
divided into a plurality of sliding surfaces. The configuration of
the main shaft 109 shown in FIG. 2, i.e., the configuration in
which the sliding surface is divided into two sliding surfaces,
corresponds to the schematic diagram shown in FIG. 3B. However, the
shaft part according to the present disclosure is not thus limited.
The sliding surface of the main shaft 109 may be a single sliding
surface. For example, as shown in FIG. 3A, the outer peripheral
surface of the main shaft 109 need not be divided into a plurality
of sliding surfaces, but instead, the main shaft 109 may have only
one sliding surface 111.
[0057] A specific manner of dividing the sliding surface into a
plurality of sliding surfaces is not particularly limited.
Typically, between a plurality of sliding surfaces, a recess that
is recessed (or receding) from the sliding surfaces toward the
center axis may be formed. The recess constitutes the non-sliding
outer peripheral surface 111c as shown in FIG. 2 and FIG. 3B. A
specific shape of the recess is not particularly limited. For
example, the depth of the recess may be set to any depth, so long
as the set depth will not affect, for example, the stiffness and
strength of the main shaft 109. Similarly, the width of the recess
(i.e., the distance between the plurality of sliding surfaces) is
not particularly limited. The width of the recess can be suitably
set in accordance with how much the sliding surface is to be
narrowed down (i.e., in accordance with an intended reduction or
decrease in the sliding area).
[0058] In the case of dividing the sliding surface into a plurality
of sliding surfaces, the plurality of sliding surfaces is not
particularly limited to a specific number of surfaces. As shown in
FIG. 2 and FIG. 3B, the sliding surface may be divided into the
first sliding surface 111a and the second sliding surface 111b,
i.e., a total of two sliding surfaces. Alternatively, as shown in
FIG. 3C, the sliding surface may be divided into a first sliding
surface 111d, a second sliding surface 111e, and a third sliding
surface 111f, i.e., a total of three sliding surfaces, or may be
divided into four or more sliding surfaces. In the configuration
shown in FIG. 3C, a first non-sliding outer peripheral surface
111g, which is the same recess as the non-sliding outer peripheral
surface 111c, is positioned between the first sliding surface 111d
and the second sliding surface 111e, and a second non-sliding outer
peripheral surface 111h is positioned between the second sliding
surface 111e and the third sliding surface 111f.
[0059] In the present disclosure, the ratio of the length of a
sliding surface of the shaft part in the axial direction to the
external diameter (the diameter) of a portion of the shaft part,
the portion serving as the sliding surface, is set to less than or
equal to a predetermined value, and thereby the sliding area can be
reduced without substantially affecting the wear resistance.
Specifically, in a case where the sliding surface is a single
sliding surface (e.g., see FIG. 3A), the length of the single
sliding surface in the axial direction is a single sliding length
L, whereas in a case where the sliding surface is divided into a
plurality of sliding surfaces (e.g., FIG. 3B or FIG. 3C), the
length of one of the sliding surfaces in the axial direction, the
one sliding surface having the least length in the axial direction
among the plurality of sliding surfaces, is the single sliding
length L. Here, when the external diameter (the diameter) of a
portion of the shaft part, the portion serving as the sliding
surface, is an external diameter D, the shaft part is designed such
that the ratio L/D of the single sliding length L to the external
diameter D of the shaft part is less than or equal to 0.51.
[0060] For the sake of convenience of the description of the
external diameter D and the single sliding length L, FIG. 3A is
illustrated such that the length L of the single sliding surface
111 (i.e., the single sliding length L) is greater than the
external diameter D. If the length L of the single sliding surface
111 relative to the external diameter D is exactly as illustrated
in FIG. 3A, the ratio L/D is greater than 0.51. However, in
reality, for example, by forming a recess (a non-sliding outer
peripheral surface) on the upper portion (the eccentric shaft 110
side) or the lower portion (the lubricating oil 103 side) of the
main shaft 109 as seen from the single sliding surface 111, the
ratio L/D can be set to less than or equal to 0.51
(L/D.ltoreq.0.51).
[0061] In FIG. 3B, the sliding surface is divided into the first
sliding surface 111a and the second sliding surface 111b. In the
example shown in FIG. 3B, the length La of the upper first sliding
surface 111a in the axial direction is less than the length Lb of
the lower second sliding surface 111b in the axial direction
(La<Lb). In this case, the first sliding surface 111a is the
"sliding surface having the least length". Accordingly, the length
La of the first sliding surface 111a is the single sliding length L
(L=La). In this example, on the first sliding surface 111a, the
La/D is required to be less than or equal to 0.51.
[0062] It should be noted that, similar to FIG. 3A, FIG. 3B is
illustrated such that the length La of the first sliding surface
111a is greater than the external diameter D for the sake of
convenience of the description of the external diameter D and the
length La. Also in this case, the ratio L/D can be set to less than
or equal to 0.51 by, for example, increasing the length of the
non-sliding outer peripheral surface 111c in the axial direction or
forming an unshown non-sliding outer peripheral surface (a recess)
on the upper side of the first sliding surface 111a.
[0063] In FIG. 3C, the sliding surface is divided into the first
sliding surface 111d, the second sliding surface 111e, and the
third sliding surface 111f. In the example shown in FIG. 3C, the
length Le of the middle second sliding surface 111e in the axial
direction is less than the length Ld of the upper first sliding
surface 111d in the axial direction, and the length Ld is less than
the length Lf of the lower third sliding surface 111f in the axial
direction (Le<Ld<Lf). In this case, the second sliding
surface 111e is the "sliding surface having the least length".
Accordingly, the length Le of the second sliding surface 111e is
the single sliding length L (L=Le). In this example, on the second
sliding surface 111e, the Le/D is required to be less than or equal
to 0.51.
[0064] In the present disclosure, the lower limit value of the
ratio L/D is not particularly limited. One preferable example of
the lower limit value is 0.15 or greater. Accordingly, a preferable
range of the ratio L/D in the present disclosure is the range of
0.15 to 0.51. A more preferable lower limit of the ratio L/D is
0.30. A further preferable lower limit of the ratio L/D is
0.42.
[0065] In a case where the ratio L/D is greater than 0.51, if
low-viscosity oil (having a kinematic viscosity in the range of 1
mm.sup.2/S to 9 mm.sup.2/S at 40.degree. C.) is used as the
lubricating oil 103, even if the aforementioned sulfur-based
sliding modifier, which will be described below, is added to the
lubricating oil 103, sufficient wear resistance cannot be obtained.
On the other hand, in a case where the ratio L/D is less than 0.15,
although depending on various conditions of the shaft part, there
is a risk of the sliding surface becoming too narrow. Generally
speaking, if the ratio L/D is greater than or equal to 0.15, the
sliding area is not reduced excessively. Therefore, even if
low-viscosity oil is used as the lubricating oil 103, suitable wear
resistance of the shaft slide part can be realized by the
sulfur-based sliding modifier.
[0066] In the present disclosure, in a case where the sliding
surface is divided into a plurality of sliding surfaces,
preferably, the ratio L/D satisfies not only the condition of being
less than or equal to 0.51, but also the following condition: when
the total of the lengths of the plurality of sliding surfaces in
the axial direction is a total sliding length Lt, the ratio Lt/D of
the total sliding length Lt to the external diameter D is less than
or equal to 1.26 (Lt/D.ltoreq.1.26).
[0067] For instance, in the example shown in FIG. 3B, the sum of
the length La of the first sliding surface 111a and the length Lb
of the second sliding surface 111b is the total sliding length Lt
(Lt=La+Lb). Therefore, in this example, it will suffice if
La+Lb.ltoreq.1.26. Also, in the example shown in FIG. 3C, the sum
of the length La of the first sliding surface 111d, the length Le
of the second sliding surface 111e, and the length Lf of the third
sliding surface 111f is the total sliding length Lt (Lt=Ld+Le+Lf).
Therefore, in this example, it will suffice if
Ld+Le+Lf.ltoreq.1.26.
[0068] As described above, in a case where the sliding surface is
divided into a plurality of sliding surfaces, if the ratio L/D is
less than or equal to 0.51 and the ratio Lt/D is less than or equal
to 1.26, then in a state where low-viscosity oil is used as the
lubricating oil 103 and the sliding area is reduced, the wear
resistance of the shaft slide part derived from the sulfur-based
sliding modifier can be more improved.
[0069] In the present disclosure, the lower limit value of the
ratio Lt/D is not particularly limited. One preferable example of
the lower limit value is 0.3 or greater. Accordingly, a preferable
range of the ratio Lt/D in the present disclosure is 0.3 to 1.26. A
more preferable lower limit of the ratio Lt/D is 0.60. A further
preferable lower limit of the ratio Lt/D is 0.99. Generally
speaking, if the ratio Lt/D is greater than or equal to 0.3, the
sliding area is not reduced excessively even in a case where the
sliding surface is divided into a plurality of sliding surfaces.
For this reason, even if low-viscosity oil is used as the
lubricating oil 103, suitable wear resistance of the shaft slide
part can be realized by the sulfur-based sliding modifier.
[0070] It should be noted that, in the examples shown in FIG. 3A to
FIG. 3C, the main shaft 109 of the crank shaft 108 is referred to
as the shaft part, and the ratio L/D and the ratio Lt/D are
described about the main shaft 109. However, the present disclosure
is not thus limited. The same is true of the eccentric shaft 110.
Specifically, in a case where a sliding surface of the eccentric
shaft 110, the sliding surface being configured to slide on the
eccentric bearing 119, is a single sliding surface, the length of
the single sliding surface in the axial direction is the single
sliding length L, whereas in a case where the sliding surface of
the eccentric shaft 110 is divided into a plurality of sliding
surfaces, the length of one of the sliding surfaces in the axial
direction, the one sliding surface having the least length in the
axial direction among the plurality of sliding surfaces, is the
single sliding length L. In these cases, the ratio L/D of the
single sliding length L to the external diameter D of the eccentric
shaft 110 is required to be less than or equal to 0.51. Also, when
the total of the lengths of the plurality of sliding surfaces of
the eccentric shaft 110 in the axial direction is the total sliding
length Lt, the ratio Lt/D of the total sliding length Lt to the
external diameter D of the eccentric shaft 110 is required to be
less than or equal to 1.26.
[0071] Therefore, in the refrigerant compressor 100 according to
the present disclosure, at least one of the main shaft 109 and the
eccentric shaft 110, which constitute the shaft part, is required
to have a ratio L/D of less than or equal to 0.51. Similarly, at
least one of the main shaft 109 and the eccentric shaft 110 is
required to have a ratio Lt/D of less than or equal to 1.26.
[0072] [Configuration of Lubricating Oil]
[0073] Next, a more specific configuration of the lubricating oil
103 stored in the sealed container 101 is specifically
described.
[0074] The lubricating oil 103 according to the present disclosure
is not particularly limited, so long as the lubricating oil 103 has
a kinematic viscosity in the range of 1 mm.sup.2/S to 9 mm.sup.2/S
at 40.degree. C. Typically, for example, at least one oil substance
selected from the group consisting of mineral oil, alkyl benzene
oil, and ester oil can be suitably used as the lubricating oil 103.
Only one of these oil substances may be used as the lubricating oil
103, or a suitable combination of two or more of the oil substances
may be used as the lubricating oil 103. The definition of the
combination of two or more of the oil substances herein includes
not only a combination of two different oil substances that are
both, for example, mineral oils, but also a combination of, for
example, at least one oil substance that is a mineral oil and at
least one oil substance that is an alkyl benzene oil (or at least
one oil substance that is an ester oil).
[0075] The lubricating oil 103 according to the present disclosure
contains not only the above oil substance(s) but also the
aforementioned sulfur-based sliding modifier. The sulfur-based
sliding modifier may be any sulfur-based sliding modifier, so long
as the sulfur-based sliding modifier allows the material of the
shaft part (shaft part material) and sulfur to react with each
other. Accordingly, the sliding modifier may be sulfur, or may be a
sulfur compound that contains sulfur and that is reactive with the
shaft part material. For example, if the material of the shaft part
is a ferrous material, then examples of sulfur compounds usable as
the sliding modifier include a sulfurized olefin, a sulfide-based
compound (e.g., dibenzyl disulfide (DBDS)), a xanthate, a
thiadiazole, a thiocarbonate, a sulfurized oil or fat, a sulfurized
ester, a dithiocarbamate, and a sulfurized terpene.
[0076] The sulfur-based sliding modifier content in the lubricating
oil 103 is not particularly limited. Preferably, the sliding
modifier is added to the lubricating oil 103, such that the sliding
modifier content therein in terms of the atomic weight of sulfur is
greater than or equal to 100 ppm. The lower limit value of the
addition amount of the sliding modifier (i.e., the lower limit
value of the sliding modifier content) being 100 ppm in terms of
the atomic weight of sulfur is greater than the upper limit value
of a general addition amount of a sulfur-based extreme-pressure
additive that will be described below.
[0077] If the sliding modifier content (the addition amount of the
sliding modifier) is less than 100 ppm in terms of the atomic
weight of sulfur, although depending on various conditions, there
is a risk that suitable wear resistance of the shaft slide part
cannot be realized in a state where low-viscosity oil is used as
the lubricating oil 103 and the sliding area of the shaft slide
part is reduced. A preferable lower limit of the sulfur-based
sliding modifier content is, for example, greater than or equal to
150 ppm in terms of the atomic weight of sulfur. Also, a preferable
upper limit of the sulfur-based sliding modifier content is, for
example, less than or equal to 1000 ppm, and more preferably less
than or equal to 500 ppm, in terms of the atomic weight of
sulfur.
[0078] A compound that is the same as a known sulfur-based
extreme-pressure additive can be used as the sulfur-based sliding
modifier in the present disclosure. However, alternatively, a
compound that is more reactive with the shaft part material than a
known extreme-pressure additive can be used as the sulfur-based
sliding modifier in the present disclosure. Further alternatively,
a known extreme-pressure additive in an amount greater than a
general addition amount (i.e., greater than a general additive
content) may be added to the lubricating oil 103.
[0079] Generally speaking, an extreme-pressure additive is a
compound containing an active element such as sulfur, halogen, or
phosphorus, and chemically reacts with the surface of the material
of which a slide part is made (i.e., chemically reacts with a
sliding surface) to form a film. The presence of the film
suppresses, for example, wear, seizing, or fusion of slide
members.
[0080] It is known that sulfur-containing compounds easily react
with copper. For example, Reference Literature 1 (Japanese
Laid-Open Patent Application Publication No. 2006-117720) discloses
that although sulfur-containing anti-wear agents are effective to
prevent corrosion wear of a lead-containing slide member, such a
sulfur-containing anti-wear agent tends to cause sulfurized
corrosion of a slide member that contains a non-ferrous base metal
different from lead, for example, copper (see paras. [0006] to
[0007] of Reference Literature 1).
[0081] In the refrigerant compressor 100, copper wire is used as
the winding of the electric element 106. Also, in a
refrigerator-freezer using the refrigerant compressor 100,
generally speaking, copper pipes are often used as refrigerant
piping. As previously described, copper tends to corrode by
reacting with a sulfur-containing compound. For this reason, when
using a sulfur-based extreme-pressure additive, it is necessary to
take measures to avoid or hinder the corrosion of a member made of
copper (or a copper-containing member) included in the refrigerant
compressor 100 or the refrigerator-freezer, thereby preventing
lowering of the reliability thereof.
[0082] The applicant of the present application discloses, in
Reference Literature 2 (Japanese Patent No. 5671695), that in the
case of using a sulfur-based extreme-pressure additive in the
refrigerator oil of a refrigerator-freezer, a sulfur-based
extreme-pressure additive in which the number of sulfur cross-links
is 3 or less is used so that the sulfur-based extreme-pressure
additive will not react with copper in a refrigerant circulation
passage. Preferably, a metal deactivator is used together with the
sulfur-based extreme-pressure additive.
[0083] In this respect, the inventors of the present invention have
conducted diligent studies including experimental verification. As
a result of the studies, they have found that in the case of using
low-viscosity oil as the lubricating oil 103 and reducing the
sliding area of the shaft slide part such that the aforementioned
ratio L/D is less than or equal to 0.51, not only is favorable wear
resistance realized, but also the corrosion of a member made of
copper (or a copper-containing member) can be substantially avoided
by using a sulfur-based compound having higher reactivity as the
sliding modifier or by increasing the adding amount of the sliding
modifier (i.e., by increasing the sliding modifier content).
[0084] Further, in the refrigerant compressor 100 according to the
present disclosure, a known extreme-pressure additive may be added
to the lubricating oil 103 in addition to the sulfur-based sliding
modifier. A specific extreme-pressure additive to be added to the
lubricating oil 103 is not particularly limited, and a known
extreme-pressure additive can be suitably used. Examples of known
extreme-pressure additives that can be suitably used include a
phosphorus-based compound, such as a phosphate ester, and a
halogenated compound, such as a chlorine-based hydrocarbon or a
fluorine-based hydrocarbon. Only one of these extreme-pressure
additives may be added to the lubricating oil composition, or a
suitable combination of two or more of the extreme-pressure
additives may be added to the lubricating oil composition.
[0085] Among these extreme-pressure additives, a phosphorus-based
compound can be used preferably. Typical examples of the
phosphorus-based compound include tricresyl phosphate (TCP),
tributyl phosphate (TBP), and triphenyl phosphate (TPP). Among
these, TCP is particularly preferable. In addition to the
sulfur-based sliding modifier, a phosphorus-based extreme-pressure
additive may be added to the lubricating oil 103, and thereby, for
example, wear of the shaft slide part can be reduced favorably.
[0086] The amount of the extreme-pressure additive to be added to
the lubricating oil composition is not particularly limited. For
example, in a case where the lubricating oil 103 (oil substance) is
a low-polarity substance such as mineral oil or alkyl benzene oil,
a suitable addition amount of the extreme-pressure additive is in
the range of 0.5 to 8.0% by weight, and more preferably in the
range of 1 to 3% by weight.
[0087] Further, in the refrigerant compressor 100 according to the
present disclosure, known various additives may be added to the
lubricating oil 103 in addition to the sliding modifier and the
extreme-pressure additive. Those known in the field of the
lubricating oil 103 can be suitably used as the various additives
to be added to the lubricating oil 103. Typical examples of such
additives include an oily agent, an antioxidant, an acid-acceptor,
a metal deactivator, a defoaming agent, an anti-corrosive agent,
and a dispersant. In other words, the lubricating oil 103 used in
the refrigerant compressor 100 according to the present disclosure
is a lubricating oil composition constituted by at least the oil
substance and the sliding modifier. The lubricating oil composition
may contain an extreme-pressure additive (in particular, a
phosphorus-based extreme-pressure additive), and may also contain
other additives.
[0088] As described above, the refrigerant compressor 100 according
to the present disclosure satisfies the following conditions: (1)
the lubricating oil 103 has a kinematic viscosity in the range of 1
mm.sup.2/S to 9 mm.sup.2/S at 40.degree. C.; (2) the ratio L/D of
the single sliding length L to the external diameter D of the shaft
part is less than or equal to 0.51; and (3) a sulfur-based sliding
modifier is used. Further, in a case where the sliding surface is
divided into a plurality of sliding surfaces, the refrigerant
compressor 100 preferably satisfies the following condition (4):
the ratio Lt/D of the total sliding length Lt to the external
diameter D is less than or equal to 1.26. By satisfying these
conditions, the shaft part and the bearing part can be lubricated
favorably, which makes it possible to favorably suppress wear of
the shaft slide part. Consequently, the reliability of the
refrigerant compressor 100 can be further improved.
[0089] It should be noted that the refrigerant compressor 100
according to the present disclosure may be inverter-driven at a
plurality of operating frequencies as previously mentioned. In a
case where the refrigerant compressor 100 is inverter-driven, there
are two operation modes of the electric element 106, in one of
which the electric element 106 is operated at a low rotation speed
(low-speed operation), and in the other of which the electric
element 106 is operated at a high rotation speed (high-speed
operation). When the electric element 106 is operated at a low
rotation speed, the amount of lubricating oil 103 supplied to the
shaft slide part decreases. In the present disclosure, although the
sliding area of the shaft slide part is reduced, even when the
amount of lubricating oil 103 supplied to the shaft slide part
decreases, favorable wear resistance can be realized.
[0090] Also, even when the rotation speed of the electric element
106 shifts from the low rotation speed to the high rotation speed
(i.e., even when the rotation speed of the electric element 106
increases), favorable wear resistance can be realized. Therefore,
in a case where the refrigerant compressor 100 is inverter-driven,
regardless of whether the low-speed operation is being performed or
the high-speed operation is being performed, the wear resistance of
the shaft slide part derived from the sulfur-based sliding modifier
can be realized. Consequently, the reliability of the refrigerant
compressor 100 can be improved, and also, the operating efficiency
can be improved.
[0091] As described above, in the refrigerant compressor 100
according to the present disclosure, the lubricating oil 103 is
low-viscosity oil; the ratio L/D of the single sliding length L to
the external diameter D is less than or equal to 0.51 regardless of
whether the sliding surface of the shaft part is a single sliding
surface or a plurality of sliding surfaces; and the lubricating oil
103 contains a sulfur-based sliding modifier. Owing to these
features, even though the lubricating oil 103 is low-viscosity oil
and the sliding area is reduced such that the ratio L/D is less
than or equal to 0.51, favorable wear resistance of the slide part
can be realized by the sulfur-based sliding modifier. Consequently,
the hermetic refrigerant compressor can be obtained, which makes it
possible to achieve high reliability of the shaft part, which is
pivotally supported by the bearing part, even with the use of the
lubricating oil 103 having a reduced viscosity.
Embodiment 2
[0092] In Embodiment 2, one example of a refrigerator-freezer that
includes the refrigerant compressor 100 described above in
Embodiment 1 is specifically described with reference to FIG. 4.
FIG. 4 is a schematic diagram showing a schematic configuration of
the refrigerator-freezer including the refrigerant compressor 100
according to Embodiment 1. Therefore, in Embodiment 2, only a
fundamental configuration of the refrigerator-freezer is briefly
described.
[0093] As shown in FIG. 4, the refrigerator-freezer according to
Embodiment 2 includes, for example, a body 275, a dividing wall
278, and a refrigerant circuit 270. The body 275 is constituted by
a thermally-insulated box, a door, and so forth. The box is
configured to have one opening face, and the door is configured to
open/close the opening of the box. The interior of the body 275 is
divided by the dividing wall 278 into a product storage space 276
and a machinery room 277. An unshown air feeder is provided in the
storage space 276. It should be noted that the interior of the body
275 may be divided into, for example, spaces that are different
from the storage space 276 and the machinery room 277.
[0094] The refrigerant circuit 270 is configured to cool the inside
of the storage space 276. For example, the refrigerant circuit 270
includes the refrigerant compressor 100 described above in
Embodiment 1, a radiator 272, a decompressor 273, and a heat
absorber 274, which are connected by piping in an annular manner.
The heat absorber 274 is disposed in the storage space 276. Cooling
heat of the heat absorber 274 is stirred by the unshown air feeder
so as to circulate inside the storage space 276 as indicated by a
dashed arrow in FIG. 4. In this manner, the inside of the storage
space 276 is cooled.
[0095] As described above in Embodiment 1, the refrigerant
compressor 100 included in the refrigerant circuit 270 satisfies
the following conditions: (1) the lubricating oil 103 has a
kinematic viscosity in the range of 1 mm.sup.2/S to 9 mm.sup.2/S at
40.degree. C.; (2) the ratio L/D of the single sliding length L to
the external diameter D of the shaft part is less than or equal to
0.51; and (3) a sulfur-based sliding modifier is used. Further, in
a case where the sliding surface is divided into a plurality of
sliding surfaces, the refrigerant compressor 100 preferably
satisfies the following condition (4): the ratio Lt/D of the total
sliding length Lt to the external diameter D is less than or equal
to 1.26. By satisfying these conditions, the reliability of the
refrigerant compressor 100 can be further improved.
[0096] As described above, the refrigerator-freezer according to
Embodiment 2 includes the above-described refrigerant compressor
100 according to Embodiment 1. In the refrigerant compressor 100,
the low-viscosity lubricating oil 103 is used; the sliding area of
the shaft slide part is reduced; and the shaft part has high
reliability. Since the refrigerator-freezer includes the hermetic
refrigerant compressor, which is highly efficient and highly
reliable, the power consumption of the refrigerator-freezer can be
reduced, and also, the refrigerator-freezer can be made highly
reliable.
[0097] It should be noted that the present invention is not limited
to the embodiments described above, and various modifications can
be made within the scope of the Claims. Embodiments obtained by
suitably combining technical means that are disclosed in different
embodiments and variations also fall within the technical scope of
the present invention.
[0098] From the foregoing description, numerous modifications and
other embodiments of the present invention are obvious to a person
skilled in the art. Therefore, the foregoing description should be
interpreted only as an example and is provided for the purpose of
teaching the best mode for carrying out the present invention to a
person skilled in the art. The structural and/or functional details
may be substantially modified without departing from the spirit of
the present invention.
INDUSTRIAL APPLICABILITY
[0099] As described above, the present invention makes it possible
to provide a refrigerant compressor that uses low-viscosity
lubricating oil and yet has excellent reliability and to provide a
refrigerator-freezer using the refrigerant compressor. Therefore,
the present invention is widely applicable to various equipment
that uses a refrigeration cycle.
REFERENCE SIGNS LIST
[0100] 100: refrigerant compressor [0101] 101: sealed container
[0102] 103: lubricating oil [0103] 106: electric element [0104]
107: compression element [0105] 108: crank shaft [0106] 109: main
shaft (shaft part) [0107] 110: eccentric shaft (shaft part) [0108]
111: single sliding surface [0109] 111a: first sliding surface
[0110] 111b: second sliding surface [0111] 111c: non-sliding outer
peripheral surface [0112] 111d: first sliding surface [0113] 111e:
second sliding surface [0114] 111f: third sliding surface [0115]
111g: first non-sliding outer peripheral surface [0116] 111h:
second non-sliding outer peripheral surface [0117] 112: cylinder
block [0118] 114: main bearing (bearing part) [0119] 119: eccentric
bearing (bearing part) [0120] 270: refrigerant circuit [0121] 272:
radiator [0122] 273: decompressor [0123] 274: heat absorber
* * * * *