Technical Field
[0001] The present invention relates to an oxide film formed on a surface of a base material
that is a sintered body (iron-based sintered body) made of an iron-based material,
a sliding member on which the oxide film is formed, and an apparatus including the
sliding member.
Background Art
[0002] A sliding portion is constituted by combining a plurality of sliding members through
sliding surfaces. Typically, when the type of a sliding operation is reciprocating
sliding or rotational sliding, an abrasion resistance film is formed on the sliding
surface of at least one of the sliding members constituting the sliding portion. Typical
examples of the abrasion resistance film include a phosphate film, a gas nitriding
film, and an iron oxide-based oxide film constituted by a triiron tetroxide (Fe
3O
4) monolayer. The oxide film constituted by the triiron tetroxide (Fe
3O
4) monolayer is typically formed by a blackening treatment (also called black oxide
finish) method.
[0003] The abrasion resistance film covers the surface of the base material constituting
the sliding member. The base material is typically metal, and at least a part of the
surface of the base material is a sliding surface. When the sliding operation is performed
at the sliding portion, lubricating oil is supplied to the sliding surfaces. Therefore,
the abrasion of the sliding members is prevented or suppressed by the lubricating
oil during the sliding operation, and an increase in sliding resistance by the contact
between the metals (base materials) is suppressed. With this, the smooth sliding operation
is secured at the sliding portion for a long period of time.
[0004] For example, PTL 1 discloses a refrigerant compressor including a sliding portion
at which a phosphate film is used as the abrasion resistance film. According to this
refrigerant compressor, in order to prevent the abrasion of the sliding portion, such
as a piston or a crank shaft, for example, the phosphate film is formed on the sliding
surface. By the formation of the phosphate film, depressions and projections on a
machined surface subjected to machine finish are eliminated, and initial fitting between
the sliding members can be made satisfactory.
[0005] For example, rotational motion is performed at a main shaft portion of the crank
shaft and a bearing portion included in the refrigerant compressor. When the refrigerant
compressor is in a stop state, the rotational speed is 0 m/s. When the refrigerant
compressor starts up, the rotational motion starts from the metallic contact state.
Therefore, large frictional resistance force acts. In this refrigerant compressor,
the phosphate film is formed on the main shaft portion of the crank shaft, and the
phosphate film has an initial fitting property. Therefore, abnormal abrasion by the
metallic contact at the time of the start-up can be prevented by the phosphate film.
Citation List
Patent Literature
[0006] PTL 1: Japanese Laid-Open Patent Application Publication No.
7-238885
Summary of Invention
Technical Problem
[0007] In recent years, in order to improve the efficiency of the refrigerant compressor,
lower-viscosity lubricating oil is used, and a slide length of the sliding portion
is designed to be shorter. Therefore, the conventional phosphate film disclosed in
PTL 1 may quickly abrade or wear, and it may be difficult to maintain the fitting
effect. With this, self-abrasion resistance of the phosphate film may deteriorate.
[0008] Further, in the refrigerant compressor, a load acting on the main shaft portion of
the crank shaft while the crank shaft rotates once significantly fluctuates. In accordance
with the load fluctuation, refrigerant gas dissolved in the lubricating oil vaporizes
and generates bubbles between the crank shaft and the bearing portion in some cases.
By this generation of the bubbles, the frequency of the break of the oil film and
the occurrence of the metallic contact increases. As a result, the phosphate film
formed on the main shaft portion of the crank shaft may quickly abrade, and a friction
coefficient may increase.
[0009] Further, as an abrasion coefficient increases, heat generation of the sliding portion
increases, and this may cause abnormal abrasion, such as adhesive wear. As the sliding
portion, the refrigerant compressor includes a piston and a bore in addition to the
main shaft portion of the crank shaft and the bearing portion. The same phenomenon
as above may occur between the piston and the bore.
[0010] In PTL 1, the base material on which the phosphate film is formed is limited to cast
iron. However, a sintered body is recently used as the base material in many cases.
Therefore, PTL 1 does not especially disclose that a satisfactory abrasion resistance
film is formed on the surface of the base material that is the iron-based sintered
body.
[0011] The present invention was made to solve the above problems, and an object of the
present invention is to provide: an oxide film provided on a surface of a base material
that is an iron-based sintered body, the oxide film being capable of exhibiting satisfactory
abrasion resistance; a sliding member on which the oxide film is formed; and an apparatus
including the sliding member.
Solution to Problem
[0012] To solve the above problems, an oxide film according to the present invention is
formed on a surface of a base material that is a sintered body constituted by an iron-based
material. The oxide film includes: a first layer constituted by at least fine crystals;
a second layer located under the first layer and containing columnar structures; and
a third layer containing columnar structures and provided on the second layer through
an interface so as to be located close to the base material.
[0013] According to the above configuration, the oxide film includes the dense first layer
on the outermost surface thereof. Therefore, satisfactory abrasion resistance can
be given to the sliding surface of the sliding member. In addition, although the base
material of the sliding member is the iron-based sintered body, the base material
of the sliding member does not require a sealing treatment since the first layer on
the outermost surface is constituted by dense fine crystals. Therefore, not only the
improvement of the abrasion resistance but also the reduction in the manufacturing
cost can be realized. The second layer containing the columnar structures and the
third layer containing the columnar structures are interposed between the first layer
and the base material. Therefore, the adhesive property of the first layer on the
outermost surface with respect to the base material can be made further satisfactory.
On this account, the stability of the oxide film as the abrasion resistance film can
be made further satisfactory. Further, the base material is the iron-based sintered
body, and the oxide film as the satisfactory abrasion resistance film is formed on
the surface of the base material. Therefore, the weight of the sliding member can
be reduced. In addition, the conventional sliding member made of cast iron can be
replaced with the sliding member made of the iron-based sintered body.
[0014] To solve the above problems, a sliding member according to the present invention
includes the above oxide film formed on a sliding surface of the base material that
is the sintered body constituted by the iron-based material.
[0015] To solve the above problems, an apparatus according to the present invention includes
the above sliding member.
[0016] The above object, other objects, features, and advantages of the present invention
will be made clear by the following detailed explanation of preferred embodiments
with reference to the attached drawings.
Advantageous Effects of Invention
[0017] By the above configurations, the present invention can obtain effects of being able
to provide: an oxide film formed on a surface of a base material that is an iron-based
sintered body, the oxide film being capable of exhibiting satisfactory abrasion resistance;
a sliding member on which the oxide film is formed; and an apparatus including the
sliding member.
Brief Description of Drawings
[0018]
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.
Fig. 2 is a SIM (scanning ion microscope) image showing one example of a result of
a SIM observation of an oxide film formed at a sliding portion included in the refrigerant
compressor shown in Fig. 1.
Fig. 3 is a schematic diagram showing one example of the configuration of a freezer
including the refrigerant compressor shown in Fig. 1.
Description of Embodiments
[0019] An oxide film according to the present disclosure is formed on a surface of a base
material that is a sintered body constituted by an iron-based material. The oxide
film includes: a first layer constituted by at least fine crystals; a second layer
located under the first layer and containing columnar structures; and a third layer
containing columnar structures and provided on the second layer through an interface
so as to be located close to the base material.
[0020] According to the above configuration, the oxide film includes the dense first layer
on the outermost surface thereof. Therefore, satisfactory abrasion resistance can
be given to the sliding surface of the sliding member. In addition, although the base
material of the sliding member is the iron-based sintered body, the base material
of the sliding member does not require a sealing treatment since the first layer on
the outermost surface is constituted by dense fine crystals. Therefore, not only the
improvement of the abrasion resistance but also the reduction in the manufacturing
cost can be realized. The second layer containing the columnar structures and the
third layer containing the columnar structures are interposed between the first layer
and the base material. Therefore, the adhesive property of the first layer on the
outermost surface with respect to the base material can be made further satisfactory.
On this account, the stability of the oxide film as the abrasion resistance film can
be made further satisfactory. Further, the base material is the iron-based sintered
body, and the oxide film as the satisfactory abrasion resistance film is formed on
the surface of the base material. Therefore, the weight of the sliding member can
be reduced. In addition, the conventional sliding member made of cast iron can be
replaced with the sliding member made of the iron-based sintered body.
[0021] The above oxide film may be configured such that the first layer includes a dense
layer containing the fine crystals that exist more densely than the fine crystals
of the other part of the first layer.
[0022] The above oxide film may be configured such that the first to third layers are constituted
by at least diiron trioxide (Fe
2O
3) and triiron tetroxide (Fe
3O
4).
[0023] The above oxide film may be configured such that: a component contained most in the
first layer is diiron trioxide (Fe
2O
3); a component contained most in the second layer is triiron tetroxide (Fe
3O
4); and a component contained most in the third layer is triiron tetroxide (Fe
3O
4).
[0024] The above oxide film may be configured such that: a crystal grain diameter of the
first layer falls within a range of 0.001 to 1 µm; and the crystal grain diameter
of the first layer is smaller than a crystal grain diameter of the second layer.
[0025] The above oxide film may be configured such that the columnar structures contained
in the second layer are vertically long crystal structures each having an aspect ratio
that falls within a range of 1 to 20.
[0026] The above oxide film may be configured such that the columnar structures contained
in the third layer are vertically long crystal structures each having an aspect ratio
that falls within a range of 1 to 15.
[0027] The above oxide film may be configured such that a film thickness of the oxide film
falls within a range of 1 to 5 µm.
[0028] A sliding member according to the present disclosure includes the above oxide film
formed on a sliding surface of the base material that is the sintered body constituted
by the iron-based material.
[0029] The above sliding member may be configured such that the sintered body contains iron
at 90 mass % or more.
[0030] The above sliding member may be configured such that the sintered body contains at
least one of sulfur and molybdenum.
[0031] An apparatus according to the present disclosure includes the above sliding member.
[0032] Hereinafter, typical embodiments of the present disclosure will be explained with
reference to the drawings. In the following explanation and the drawings, the same
reference signs are used for the same or corresponding components, and a repetition
of the same explanation is avoided.
Embodiment 1
[0033] In Embodiment 1, an oxide film according to the present disclosure, a sliding member
including the oxide film, and an apparatus including the sliding member will be explained
based on an example in which the oxide film is formed at a sliding portion of a refrigerant
compressor. For convenience of explanation, the apparatus including the sliding member
on which the oxide film according to the present disclosure is formed is referred
to as an "oxide film applied apparatus." Therefore, the refrigerant compressor in
Embodiment 1 corresponds to the oxide film applied apparatus.
Configuration of Refrigerant Compressor
[0034] First, a typical example of the refrigerant compressor according to Embodiment 1
will be specifically explained with reference to Figs. 1 and 2. Fig. 1 is a sectional
view of a refrigerant compressor 100 according to Embodiment 1. Fig. 2 is a SIM (scanning
ion microscope) image showing one example of a result of a SIM observation of the
oxide film provided at the sliding portion of the refrigerant compressor 100.
[0035] As shown in Fig. 1, in the refrigerant compressor 100, the sealed container 101 is
filled with refrigerant gas 102 that is R134a, and ester oil as the lubricating oil
103 is stored in a bottom portion of the sealed container 101. The sealed container
101 accommodates an electric component 106 and a compression component 107. The electric
component 106 is constituted by a stator 104 and a rotor 105, and the compression
component 107 is a reciprocating type and is driven by the electric component 106.
[0036] The compression component 107 is constituted by a crank shaft 108, a cylinder block
112, a piston 132, and the like. The configuration of the compression component 107
will be explained below.
[0037] The crank shaft 108 is constituted by at least a main shaft portion 109 and an eccentric
shaft 110. The main shaft portion 109 is press-fitted and fixed to the rotor 105.
The eccentric shaft 110 is formed eccentrically with respect to the main shaft portion
109. An oil supply pump 111 communicating with the lubricating oil 103 is included
at a lower end of the crank shaft 108.
[0038] In the crank shaft 108, a sintered body (iron-based sintered body) made of an iron-based
material is used as a base material 175, and an oxide film 170 is formed on the surface
of the base material 175. A typical example of the oxide film 170 in Embodiment 1
is shown in Fig. 2. Fig. 2 shows one example of a result of an observation of a section
of the oxide film 170 with a SIM (scanning ion microscope) and shows a whole image
of the oxide film 170 in a thickness direction. It should be noted that the sliding
member shown in Fig. 2 is the piston 132.
[0039] The oxide film 170 in Embodiment 1 is constituted by a first layer 171, a second
layer 172, and a third layer 173, and an interface 174 exists between the second layer
172 and the third layer 173. A specific configuration of the oxide film 170 will be
described later.
[0040] The cylinder block 112 is made of cast iron. The cylinder block 112 forms a substantially
cylindrical bore 113 and includes a bearing portion 114 supporting the main shaft
portion 109.
[0041] The rotor 105 includes a flange surface 120, and an upper end surface of the bearing
portion 114 is a thrust surface 122. A thrust washer 124 is inserted between the flange
surface 120 and the thrust surface 122 of the bearing portion 114. The flange surface
120, the thrust surface 122, and the thrust washer 124 constitute a thrust bearing
126.
[0042] The piston 132 is loosely fitted into the bore 113 with a certain amount of clearance
and is made of an iron-based material. The piston 132 forms a compression chamber
134 together with the bore 113. The piston 132 is coupled to the eccentric shaft 110
by a connecting rod 138 as a coupler through a piston pin 137. An end surface of the
bore 113 is sealed by a valve plate 139.
[0043] A head 140 forms a high pressure chamber. The head 140 is fixed to the valve plate
139 at an opposite side of the bore 113. A suction tube (not shown) is fixed to the
sealed container 101 and connected to a low-pressure side (not shown) of a refrigeration
cycle. The suction tube introduces the refrigerant gas 102 into the sealed container
101. A suction muffler 142 is sandwiched between the valve plate 139 and the head
140.
[0044] Operations of the refrigerant compressor 100 configured as above will be explained
below.
[0045] Electric power supplied from a commercial power supply (not shown) is supplied to
the electric component 106 and rotates the rotor 105 of the electric component 106.
The rotor 105 rotates the crank shaft 108, and an eccentric motion of the eccentric
shaft 110 is transmitted from the connecting rod 138 of the coupler through the piston
pin 137 to drive the piston 132. The piston 132 reciprocates in the bore 113 to suck
from the suction muffler 142 the refrigerant gas 102 introduced into the sealed container
101 through the suction tube (not shown) and compress the refrigerant gas 102 in the
compression chamber 134.
[0046] In accordance with the rotation of the crank shaft 108, the lubricating oil 103 is
supplied from the oil supply pump 111 to respective sliding portions to lubricate
the sliding portions. In addition, the lubricating oil 103 serves as a seal between
the piston 132 and the bore 113. It should be noted that the sliding portion denotes
a portion where sliding surfaces of a plurality of sliding members contact and slide
on each other.
[0047] In recent years, in order to further improve the efficiency of the refrigerant compressor
100, for example, (1) the lubricating oil 103 having lower viscosity is used, and
(2) a slide length of each sliding member constituting the sliding portion (i.e.,
the slide length of the sliding portion) is designed to be shorter. Therefore, the
slide condition is becoming severer. To be specific, the oil film of the sliding portion
tends to be thinner, and it tends to be difficult to form the oil film of the sliding
portion.
[0048] In addition, in the refrigerant compressor 100, the eccentric shaft 110 of the crank
shaft 108 is formed eccentrically with respect to the bearing portion 114 of the cylinder
block 112 and the main shaft portion 109 of the crank shaft 108. Therefore, by gas
pressure of the compressed refrigerant gas 102, a fluctuating load that fluctuates
is applied between the main shaft portion 109 of the crank shaft 108 and the connecting
rod 138 of the eccentric shaft 110. In accordance with the load fluctuation, the refrigerant
gas 102 dissolved in the lubricating oil 103 repeatedly vaporizes between, for example,
the main shaft portion 109 and the bearing portion 114. Therefore, bubbles are generated
in the lubricating oil 103.
[0049] Therefore, at the sliding portion, such as a portion between the main shaft portion
109 of the crank shaft 108 and the bearing portion 114, the oil film breaks, and the
frequency of the metallic contact between the sliding surfaces increases.
[0050] However, the oxide film 170 including the above three layers is formed on the sliding
portion of the refrigerant compressor 100, i.e., on the sliding portion of the the
crank shaft 108 as one example in Embodiment 1. Therefore, even if the frequency of
the break of the oil film increases, the abrasion of the sliding surface can be suppressed
for a long period of time.
[0051] In Embodiment 1, one example of the sliding member is the crank shaft 108. However,
when the oxide film applied apparatus is the refrigerant compressor 100, the sliding
members are not limited to the main shaft portion 109 of the crank shaft 108 and the
bearing portion 114. The sliding members in the refrigerant compressor 100 configured
as above may be the piston 132, the bore 113, and the connecting rod 138. For example,
as described above, the sliding member shown in Fig. 2 is the piston 132. In the present
disclosure, the oxide film 170 as an abrasion resistance film is only required to
be formed on the surface of such sliding member.
Configuration of Oxide Film
[0052] Next, the oxide film 170 according to the present disclosure will be more specifically
explained. As described above, the oxide film 170 according to the present disclosure
is constituted by the first layer 171, the second layer 172, and the third layer 173,
and the interface 174 exists between the second layer 172 and the third layer 173.
[0053] The first layer 171 is located on an outermost surface of the base material 175 that
is the iron-based sintered body. The first layer 171 is constituted by at least fine
crystals. A crystal grain diameter of the fine crystal constituting the first layer
171 is only required to be smaller than at least a crystal grain diameter of the crystal
constituting the second layer 172 (or the third layer 173). In the present disclosure,
the crystal grain diameter of the first layer 171 is only required to fall within
a range of 0.001 to 1 µm. Further, as shown in Fig. 2, the first layer 171 includes
a dense layer 171a constituted by denser fine crystals. The dense layer 171a is constituted
by the fine crystals that exist more densely than the fine crystals of the other part
of the first layer 171.
[0054] The second layer 172 is located under the first layer 171 and contains columnar structures
that are vertically long (long in the thickness direction of the oxide film 170) crystal
structures. The third layer 173 is provided on the second layer 172 through the interface
so as to be located close to the base material 175. As with the second layer 172,
the third layer 173 contains columnar structures that are vertically long crystal
structures. As above, both the second layer 172 and the third layer 173 contain the
columnar structures, but as shown in Fig. 2, the second layer 172 and the third layer
173 are clearly divided by the interface 174.
[0055] The second layer 172 and the third layer 173 are only required to be constituted
by at least the columnar structures, and the columnar structures of the second layer
172 and the columnar structures of the third layer 173 may be the same as each other.
In the present disclosure, an aspect ratio of the columnar structure constituting
the second layer 172 (for convenience sake, hereinafter referred to as a "second layer
columnar structure") tends to become higher than an aspect ratio of the columnar structure
constituting the third layer 173 (for convenience sake, hereinafter referred to as
a "third layer columnar structure").
[0056] For example, in the oxide film 170 according to Embodiment 1, the aspect ratio of
the second layer columnar structure falls within a range of 1 to 20, and the aspect
ratio of the third layer columnar structure falls within a range of 1 to 15. Needless
to say, the range of the aspect ratio of the second layer columnar structure and the
range of the aspect ratio of the third layer columnar structure are not limited to
these ranges.
[0057] The thickness (film thickness) of the entire oxide film 170 is not especially limited
and is only required to fall within a range of 1 to 5 µm. Similarly, the thickness
of the first layer 171, the thickness of the second layer 172, the thickness of the
third layer 173, the thickness of the dense layer 171a of the first layer 171, the
thickness of the interface 174 interposed between the second layer 172 and the third
layer 173 are not especially limited.
[0058] In the example shown in Fig. 2, the thickness of the first layer 171 is about 0.5
µm, the thickness of the second layer 172 is about 2.0 µm, the thickness of the third
layer 173 is about 0.6 µm, and the thickness of the interface 174 is about 0.16 µm.
Further, the first layer 171 includes a layer of dense crystals, and the thickness
of the layer is about 0.4 µm. Therefore, the thickness of the entire oxide film 170
is about 3.26 µm.
[0059] Specific types of components constituting the oxide film 170 are not especially limited,
and the first to third layers 171 to 173 are only required to be constituted by at
least diiron trioxide (Fe
2O
3) and triiron tetroxide (Fe
3O
4). More specifically, for example, a component contained most in the first layer 171
is only required to be diiron trioxide (Fe
2O
3). A component contained most in the second layer 172 is only required to be triiron
tetroxide (Fe
3O
4). A component contained most in the third layer 173 is only required to be triiron
tetroxide (Fe
3O
4). Further, the first to third layers 171 to 173 (and the interface 174) may contain
a component(s) other than diiron trioxide (Fe
2O
3) and triiron tetroxide (Fe
3O
4).
[0060] The oxide film 170 is only required to include at least the first layer 171, the
second layer 172, the third layer 173, and the interface 174 defining the second layer
172 and the third layer 173. However, the oxide film 170 may contain other layer(s)
and the like. As shown in Fig. 2, the first layer 171 may be formed on the outermost
surface and include the dense layer 171a constituted by the fine crystals arranged
more densely. However, the first layer 171 does not necessarily have to include the
dense layer 171a. The first layer 171 itself is constituted by the fine crystals that
are denser than the fine crystals of the other two layers. Therefore, even if the
first layer 171 does not include the dense layer 171a, the first layer 171 has the
crystal structures that are denser than the crystal structures of the other two layers.
[0061] A known method of oxidizing an iron-based material can be suitably used as a method
of producing the oxide film 170, and the method of producing the oxide film 170 is
not especially limited. Production conditions and the like can be suitably set depending
con conditions, such as the type of the iron-based sintered body that is the base
material 175, the surface state of the base material 175, and required physical properties
of the oxide film 170. In the present disclosure, the iron-based sintered body as
the base material 175 is oxidized by using known oxidizing gas, such as carbon dioxide
gas, and a known oxidation facility at several hundreds of degrees Celsius (for example,
400 to 800°C). With this, the oxide film 170 can be formed on the surface of the base
material 175.
[0062] A specific configuration of the iron-based sintered body that is the base material
175 is not especially limited, and the iron-based sintered body is only required to
be a sintered body produced by a known method using an iron-based material. The content
of iron in the iron-based sintered body (base material 175) is not especially limited.
In Embodiment 1, it is preferable to use a sintered body in which the content of iron
is 90 mass % or more. The iron-based sintered body may contain various components
other than iron. In the present disclosure, for example, the iron-based sintered body
may contain at least one of sulfur (S) and molybdenum (Mo). It should be noted that
typically, the base material 175 that is the iron-based sintered body does not contain
silicon (Si).
[0063] The oxide film 170 according to the present disclosure includes the dense first layer
171 on the outermost surface thereof. Therefore, satisfactory abrasion resistance
can be given to the sliding surface of the sliding member. In addition, the base material
175 of the sliding member is the iron-based sintered body and generally requires a
sealing treatment. However, since the outermost surface of the oxide film 170 is constituted
by the dense fine crystals, the sealing treatment is unnecessary. Therefore, not only
the improvement of the abrasion resistance but also the reduction in the manufacturing
cost can be realized.
[0064] The second layer 172 containing the columnar structures and the third layer 173 containing
the columnar structures are interposed between the first layer 171 and the iron-based
sintered body that is the base material 175. Therefore, a layer for fixing (adhering)
the first layer 171 to the base material 175 has a two-layer structure, so that the
adhesion of the first layer 171 with respect to the base material 175 can be made
further satisfactory. On this account, the stability of the oxide film 170 as the
abrasion resistance film can be made further satisfactory.
[0065] In conventional cases, when the base material 175 is an iron-based material, cast
iron or the like is used. However, in the sliding member according to the present
disclosure, the base material 175 is the iron-based sintered body, and the oxide film
170 is formed on the surface of the base material 175. Therefore, the sliding member
according to the present disclosure can be made lighter than the sliding member in
which the base material 175 is cast iron. In addition, even when the sliding member
has a shape that is difficult to realize by cast iron, such shape can be realized
by the iron-based sintered body. Therefore, the conventional sliding member made of
cast iron can be replaced with the sliding member made of the iron-based sintered
body.
Modified Example
[0066] As above, the oxide film 170 according to the present disclosure is formed on the
surface of the base material 175 that is the iron-based sintered body. The oxide film
170 includes: the first layer 171 constituted by at least the fine crystals; the second
layer 172 located under the first layer 171 and containing the columnar structures;
and the third layer 173 containing the columnar structures and provided at the second
layer 172 through the interface 174 so as to be located close to the base material
175. The sliding member according to the present disclosure is configured such that
the oxide film 170 is provided on the surface (sliding surface) of the base material
175 that is the iron-based sintered body. The apparatus according to the present disclosure
includes the sliding member according to the present disclosure. In Embodiment 1,
one example of the apparatus according to the present disclosure is the refrigerant
compressor 100.
[0067] The specific configuration of the refrigerant compressor 100 is not limited to the
above-described configuration. For example, in Embodiment 1, R134a is used as the
refrigerant. However, the type of the refrigerant is not limited to this. Similarly,
in Embodiment 1, the ester oil is used as the lubricating oil 103. However, the type
of the lubricating oil 103 is not limited to this. As the combination of the refrigerant
and the lubricating oil 103, various known combinations can be suitably used.
[0068] Especially preferred examples of the combination of the refrigerant and the lubricating
oil 103 are three combinations described below. By using such combinations, the excellent
efficiency and excellent reliability of the refrigerant compressor 100 can be realized
as with Embodiment 1.
[0069] In Combination 1, used as the refrigerant is R134a, a HFC-based refrigerant other
than R134a, or a HFC-based mixed refrigerant, and used as the lubricating oil 103
is ester oil, alkyl benzene oil other than the ester oil, polyvinyl ether, polyalkylene
glycol, or mixed oil thereof.
[0070] In Combination 2, used as the refrigerant is a natural refrigerant (such as R600a,
R290, or R744) or a mixed refrigerant thereof, and used as the lubricating oil 103
is mineral oil, ester oil, alkyl benzene oil, polyvinyl ether, polyalkylene glycol,
or mixed oil thereof.
[0071] In Combination 3, used as the refrigerant is an HFO-based refrigerant (such as R1234yf)
or a mixed refrigerant thereof, and used as the lubricating oil 103 is ester oil,
alkyl benzene oil, polyvinyl ether, polyalkylene glycol, or mixed oil thereof.
[0072] Especially, according to Combinations 2 and 3 among the above combinations, global
warming can be suppressed by using the refrigerant having a low greenhouse effect.
According to Combination 3, the above group of the examples as the lubricating oil
103 may include mineral oil.
[0073] In Embodiment 1, as described above, the refrigerant compressor 100 is a reciprocating
type. However, the refrigerant compressor according to the present disclosure is not
limited to the reciprocating type and may be other known type, such as a rotary type,
a scroll type, or a vibration type. When the refrigerant compressor to which the present
disclosure is applicable has a known configuration including the sliding portion,
a discharge valve, and the like, the same operational advantages as Embodiment 1 can
be obtained.
[0074] In Embodiment 1, the refrigerant compressor 100 is driven by a commercial power supply.
However, the refrigerant compressor according to the present disclosure is not limited
to this. For example, the refrigerant compressor may be inverter-driven at a plurality
of operation frequencies. Even when the refrigerant compressor is configured as above,
the formation of the above oxide film 170 on the sliding surface of the sliding portion
(constituted by the sliding members) included in the refrigerant compressor can realize
both the improvement of the self-abrasion resistance of the sliding portion and the
suppression of the opponent attacking property of the sliding portion. With this,
the reliability of the refrigerant compressor can be improved even at the time of
a low-speed operation in which the amount of oil supplied to each sliding portion
is small and a high-speed operation in which a rotational frequency of the electric
component increases.
Embodiment 2
[0075] In Embodiment 2, one example of a freezer including the refrigerant compressor 100
explained in Embodiment 1 will be specifically explained with reference to Fig. 3.
Fig. 3 schematically shows a schematic configuration of the freezer including the
refrigerant compressor 100 according to Embodiment 1. Therefore, in Embodiment 2,
only a basic configuration of the freezer will be explained.
[0076] As shown in Fig. 3, the freezer according to Embodiment 2 includes a main body 275,
a partition wall 278, a refrigerant circuit 270, and the like. The main body 275 is
constituted by a heat-insulation box body, a door body, and the like. The box body
includes an opening on one surface thereof, and the door body opens and closes the
opening of the box body. The inside of the main body 275 is divided by the partition
wall 278 into a storage space 276 for articles and a machine room 277. A blower (not
shown) is provided in the storage space 276. It should be noted that the inside of
the main body 275 may be divided into, for example, spaces other than the storage
space 276 and the machine room 277.
[0077] The refrigerant circuit 270 is configured to cool the inside of the storage space
276 and includes, for example, the refrigerant compressor 100 explained in Embodiment
1, a heat radiator 272, a decompressor 273, and a heat absorber 274. The refrigerant
compressor 100, the heat radiator 272, the decompressor 273, and the heat absorber
274 are annularly connected to one another by pipes. The heat absorber 274 is arranged
inside the storage space 276. As shown by broken line arrows in Fig. 3, cooling heat
of the heat absorber 274 is stirred by the blower (not shown) so as to circulate in
the storage space 276. With this, the inside of the storage space 276 is cooled.
[0078] As explained in Embodiment 1, the refrigerant compressor 100 included in the refrigerant
circuit 270 includes the sliding member in which the base material 175 is the iron-based
sintered body, and the oxide film 170 is formed on the sliding surface of the sliding
member.
[0079] As above, the freezer according to Embodiment 2 includes the refrigerant compressor
100 according to Embodiment 1. The sliding portion included in the refrigerant compressor
100 excels in abrasion resistance and adhesion to the sliding surface. Therefore,
the sliding loss of the sliding portion can be reduced, and the refrigerant compressor
100 can realize excellent reliability and excellent efficiency. As a result, the freezer
according to Embodiment 2 can reduce the power consumption, and therefore, energy
saving can be realized, and the reliability can also be improved.
[0080] As described above, in Embodiment 1, the refrigerant compressor is explained as the
oxide film applied apparatus. In Embodiment 2, the freezer including the refrigerant
compressor is explained as the oxide film applied apparatus. However, the oxide film
applied apparatus to which the present disclosure is applicable is not limited to
the refrigerant compressor and the freezer including the refrigerant compressor. The
oxide film according to the present disclosure is applicable to any apparatus as long
as the apparatus includes a sliding member which performs reciprocating sliding, rotational
sliding, or other sliding.
[0081] Specifically, examples include: various operating apparatuses such as pumps, motors,
engines, and expanders; various freezers, such as refrigerators, freezing display
cases, and air conditioners; home electric appliances, such as washing machines and
cleaners; centrifuges; and facility apparatuses, such as built-in apparatuses.
[0082] The present invention is not limited to the above described embodiments and may be
changed in various ways within the scope of the claims, and embodiments obtained by
suitably combining technical means disclosed in different embodiments and/or plural
modified examples are included in the technical scope of the present invention.
[0083] From the foregoing explanation, many modifications and other embodiments of the present
invention are obvious to one skilled in the art. Therefore, the foregoing explanation
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 one skilled in the art. The
structures and/or functional details may be substantially modified within the scope
of the present invention.
Industrial Applicability
[0084] As above, the oxide film according to the present invention can exhibit high abrasion
resistance for a long period of time even under severe environments, for example.
Therefore, the reliability of the sliding portion can be improved. On this account,
the present invention is widely applicable to parts and apparatuses including various
sliding members or various sliding portions.
Reference Signs List
[0085]
- 100
- refrigerant compressor (oxide film applied apparatus)
- 108
- crank shaft (sliding member)
- 113
- bore (sliding member)
- 132
- piston (sliding member)
- 138
- connecting rod (sliding member)
- 170
- oxide film
- 171
- first layer
- 171a
- dense layer
- 172
- second layer
- 173
- third layer
- 174
- interface
- 175
- base material
- 270
- refrigerant circuit
- 272
- heat radiator
- 273
- decompressor
- 274
- heat absorber