BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a scroll compressor. More particularly, the invention
relates to a technology for reducing wear of a wall of a key groove along which a
key of an Oldham link provided in a scroll compressor slides.
Description of the Related Art
[0002] A scroll compressor is provided with an Oldham link that restricts rotation of an
orbiting scroll. The Oldham link has a pair of first keys inserted into a pair of
key grooves of the orbiting scroll and a pair of second keys inserted into a pair
of key grooves of a shaft bearing, and a direction in which the first keys can slide
in the radial direction along the key grooves and a direction in which the second
keys can slide in the radial direction along the key grooves are orthogonal to each
other.
[0003] To reduce wear of the wall of the key groove along which the key of the Oldham link
slides, highly wear-resistant hard member is disposed on the wall of the key groove
(
Japanese Patent Laid-Open No. 8-189480), or a coating of a solid lubricant is formed on the wall.
[0004] Lubricating oil pumped up from an oil storage part inside a housing through an oil
supply path inside a rotating shaft is supplied to sliding parts of the scroll compressor,
such as the rotating shaft, orbiting scroll, thrust plate, shaft bearing, and Oldham
link. As the amount of lubricating oil supplied is smaller during low-speed operation,
it is necessary to secure reliability by reducing wear of the sliding parts.
[0005] In particular, it is necessary to reduce wear of the key of the Oldham link and the
key groove in which the key slides that are located far away from a connection part
of an eccentric pin of the rotating shaft and the orbiting scroll where the lubricating
oil is present.
[0006] The present invention aims to provide a scroll compressor that can reduce wear of
a key of an Oldham link and a key groove in which the key slides.
SUMMARY OF THE INVENTION
[0007] An examination made by the present inventors of a state of the wall of a key groove
that had worn through the use of the scroll compressor has found that the amount of
wear increases gradually, for example, toward the outer peripheral-side end of the
key groove, within a range in which the key of the Oldham link shifts relative to
the key groove. This means that the key groove wears easily at the side of the open
end (outer peripheral-side end), where the key comes in contact with the wall of the
key groove in an inclined state.
[0008] Once the scroll compressor starts to be used, the surface roughness of the wall of
the key groove and the key changes until the sliding surfaces of the key and the wall
of the key groove are adapted to each other.
[0009] Accordingly, we imparted the shape and the surface roughness simulating the state
where the wall has worn through use and the state where the surface is adapted through
use to the wall of the key groove before the start of use, and confirmed that wear
was thereby reduced.
[0010] Having been devised on the basis of this finding, a scroll compressor of the present
invention includes: a fixed scroll fixed to a housing; an orbiting scroll eccentrically
connected to a rotating shaft and revolved relative to the fixed scroll; a shaft bearing
fixed to the housing and supporting the orbiting scroll; and an Oldham link interposed
between the orbiting scroll and the shaft bearing and restricting rotation of the
orbiting scroll.
[0011] The Oldham link has a first key that slides in a radial direction of the rotating
shaft along a wall of a key groove provided in the orbiting scroll, and a second key
that slides in the radial direction of the rotating shaft along a wall of another
key groove provided in the shaft bearing.
[0012] In the present invention, on the assumption of a flat reference surface in the wall
of the key groove, the wall has an offset portion that is gradually offset from the
reference surface while extending toward at least one of an outer peripheral-side
end and an inner peripheral-side end of the key groove.
[0013] In the scroll compressor of the present invention, it is preferable that a surface
roughness Ra of a sliding surface of the wall including a surface of the offset portion
be 0.2 µm or less before the start of use of the Oldham link.
[0014] "The surface roughness Ra" according to the present invention is based on JIS B 0601-2001.
[0015] In the scroll compressor of the present invention, it is preferable that a part of
an inner periphery of the key groove including at least the offset portion, or the
entire inner periphery of the key groove, be formed by a liner discrete from a main
body that is the orbiting scroll or the shaft bearing.
[0016] In the scroll compressor of the present invention, it is preferable that, as the
liner is fitted with the main body located on the rear surface side of the liner through
engagement between a recess and a protrusion, the liner be positioned in a sliding
direction that is a direction in which the first key or the second key slides.
[0017] "Engagement fitting" refers to fitting through engagement between a recess and a
protrusion.
[0018] In the scroll compressor of the present invention, it is preferable that the liner
be formed substantially in a U-shape.
[0019] In the scroll compressor of the present invention, it is preferable that a liner
groove receiving an edge of the liner be formed in a bottom of the key groove.
[0020] In the scroll compressor of the present invention, it is preferable that the liner
have a liner bottom that forms a bottom surface of the key groove and is pressed into
the main body, and a liner wall that stands on the liner bottom and includes the offset
portion.
[0021] A scroll compressor of the present invention includes: a fixed scroll fixed to a
housing; an orbiting scroll eccentrically connected to a rotating shaft and revolved
relative to the fixed scroll; a shaft bearing fixed to the housing and supporting
the orbiting scroll; and an Oldham link interposed between the orbiting scroll and
the shaft bearing and restricting rotation of the orbiting scroll, wherein the Oldham
link has a first key that slides in a radial direction of the rotating shaft along
a wall of a key groove provided in the orbiting scroll, and a second key that slides
in the radial direction of the rotating shaft along a wall of another key groove provided
in the shaft bearing, and wherein a surface roughness Ra of the wall of the key groove
before the start of use of the Oldham link is set to 0.2 µm or less.
[0022] In the above configuration, it is preferable that at least a part of an inner periphery
of the key groove for which the surface roughness Ra is set, or the entire inner periphery
of the key groove, be formed by a liner discrete from a main body that is the orbiting
scroll or the shaft bearing.
[0023] In the scroll compressor of the present invention, it is preferable that the main
body have a liner housing part that houses the liner and allows the liner to shift
in a sliding direction that is a direction in which the first key or the second key
slides.
[0024] In the scroll compressor of the present invention, it is preferable that the liner
be swingably supported on the main body located on the rear surface side of the liner.
[0025] In the scroll compressor of the present invention, it is preferable that, of the
liner and the inner periphery of the key groove, at least the liner have an oil path
which communicates with an oil sump present around a connection part of the rotating
shaft and the orbiting scroll and through which lubricating oil is supplied from the
oil sump to the wall of the key groove.
[0026] In the scroll compressor of the present invention, it is preferable that a coating
having a lubricating property is applied to the wall of the key groove.
[0027] According to the present invention, the offset portion is provided in the wall of
the key groove along which the key of the Oldham link slides, and the surface roughness
Ra of the wall of the key groove is set to 0.2 µm or less. As will be described later
in detail, these features achieve an effect of reducing wear of the key and the key
groove by preventing significant wear typically occurring at an initial stage of use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028]
FIG. 1 is a longitudinal sectional view showing a scroll compressor;
FIG. 2 is a partially enlarged view of FIG. 1, showing keys of an Oldham link;
FIG. 3 is an overall perspective view of the Oldham link;
FIG. 4A is a view showing a key groove of an orbiting scroll and the key of the Oldham
link;
FIG. 4B is a view showing a key groove of a shaft bearing and the key of the Oldham
link;
FIGS. 5A and 5B are views showing a key groove according to a first embodiment, in
which FIG. 5A is a perspective view and FIG. 5B is a plan view;
FIG. 6 is a perspective view showing another key groove according to the first embodiment;
FIGS. 7A to 7C are views illustrating a state of wear of a key groove that was checked
to determine the shape of a wall of the key groove along which a first key slides,
in which FIG. 7A is a schematic view showing the key inclined on the open end side
of the key groove, FIG. 7B is a perspective view of the key groove, and FIG. 7C is
a graph showing an image of a shape profile of the wall of the key groove in the direction
of the arrow of FIG. 7B;
FIG. 8 is a graph showing a relation between a surface roughness and a depth of wear
of the wall of the key groove;
FIG. 9A is a view showing an example in which an offset portion is formed on both
an outer peripheral-end side and an inner peripheral-end side;
FIG. 9B is a schematic view showing an oil film between the key and the wall of the
key groove;
FIGS. 10A to 10C are perspective views showing key grooves according to a second embodiment;
FIG. 11 is a perspective view showing a key groove according to a third embodiment;
FIGS. 12A and 12B are perspective views showing key grooves according to a combination
of the second embodiment and the third embodiment;
FIG. 13 is a perspective view showing a key groove according to a combination of the
second embodiment and the third embodiment;
FIGS. 14A and 14B are perspective views showing key grooves according to a fourth
embodiment;
FIG. 15 is a perspective view showing a key groove according to a fifth embodiment;
FIG. 16 is a perspective view showing a key groove according to a sixth embodiment;
FIGS. 17A and 17B are perspective views showing key grooves according to a seventh
embodiment;
FIG. 18 is a plan view showing the key groove according to the seventh embodiment;
FIGS. 19A to 19C are views showing components of a key groove according to an eighth
embodiment; and
FIG. 19D is a view showing a modified example of the components.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Embodiments of the present invention will be described below with reference to the
accompanying drawings.
[0030] First, a configuration common to the following embodiments will be described with
reference to FIG. 1 to FIG. 4.
[0031] A scroll compressor 1 shown in FIG. 1 and FIG. 2 includes a fixed scroll 2, an orbiting
scroll 3, an Oldham link 10 restricting rotation of the orbiting scroll 3, a motor
4, a rotating shaft 5, shaft bearings 6, 7, and a housing 8.
[0032] The scroll compressor 1 constitutes a refrigerator or an air conditioner.
[0033] A suction pipe 91 and a discharge pipe 92 provided in the housing 8 are connected
to a refrigerant circuit of a refrigerator or an air conditioner.
[0034] When drive current is supplied to a stator 4A of the motor 4 by a drive circuit part
(not shown), a rotor 4B of the motor 4 rotates and a rotary drive force is output
to the rotating shaft 5. The rotating shaft 5 is rotatably supported by the shaft
bearings 6, 7 fixed to the housing 8.
[0035] When the rotating shaft 5 is rotated, the orbiting scroll 3 connected through a bearing
5B to an eccentric pin 5A provided at the upper end of the rotating shaft 5 is revolved
relative to the fixed scroll 2 fixed to the housing 8. Meanwhile, rotation of the
orbiting scroll 3 is restricted by the Oldham link 10 (FIG. 3) interposed between
the orbiting scroll 3 and the shaft bearing 6.
[0036] As the orbiting scroll 3 revolves, a refrigerant inside the housing 8 is suctioned
into the gap between the orbiting scroll 3 and the fixed scroll 2. Then, the refrigerant
is compressed inside a compression chamber R between the orbiting scroll 3 and the
fixed scroll 2, as the orbiting scroll 3 revolves and the volume of the compression
chamber R decreases accordingly. A thrust load due to the pressure of the compressed
refrigerant is borne by the shaft bearing 6 that supports an end plate 3A of the orbiting
scroll 3. The compressed refrigerant is discharged through the discharge pipe 92 to
the refrigerant circuit via a discharge port 2P of the fixed scroll 2.
[0037] Lubricating oil is stored in the bottom of the housing 8. The lubricating oil is
pumped up by a pump 101, provided at the lower end of the rotating shaft 5, through
an oil supply path 5C (FIG. 2) inside the rotating shaft 5, and is supplied to sliding
parts such as the shaft bearings 6, 7, rotating shaft 5, eccentric pin 5A, orbiting
scroll 3, Oldham link 10, and thrust plate (not shown) disposed between the shaft
bearing 6 and the orbiting scroll 3.
[0038] The Oldham link 10 (also called an Oldham coupling) will be described with reference
to FIG. 2 to FIG. 4.
[0039] As shown in FIG. 3, the Oldham link 10 includes a pair of first keys 11, 11, a pair
of second keys 12, 12, and an annular coupling part 13 coupling together the keys
11, 11, 12, 12.
[0040] The first keys 11, 11, the second keys 12, 12, and the coupling part 13 are integrally
made of a metal material such as aluminum alloy.
[0041] The shaft bearing 6 and the orbiting scroll 3 that slide with the Oldham link 10
are made of a metal material such as aluminum alloy.
[0042] The first keys 11, 11 protrude from one surface 131 of the coupling part 13 in an
out-of-plane direction, while the second keys 12, 12 protrude from the other surface
132 of the coupling part 13 in an out-of-plane direction.
[0043] A direction D1 connecting the first keys 11, 11 to each other and a direction D2
connecting the second keys 12, 12 to each other both extend in the radial direction
of the coupling part 13 and are orthogonal to each other.
[0044] The first keys 11, 11 are formed in a rectangular parallelepiped shape that is long
in the direction D1.
[0045] The second keys 12, 12 are formed in a rectangular parallelepiped shape that is long
in the direction D2.
[0046] As shown in FIG. 2 and FIG. 4A, the first key 11 is fitted into a key groove 20 formed
in the end plate 3A of the orbiting scroll 3. In the end plate 3A, a pair of key grooves
20 corresponding to the pair of first keys 11 (FIG. 3) are formed.
[0047] The first key 11 slides in the key groove 20 in the radial direction with a predetermined
stroke. Hereinafter, unless otherwise mentioned, "the radial direction" refers to
the direction of the diameter passing through the centers of the rotating shaft 5
and the shaft bearing 6.
[0048] As shown in FIG. 2 and FIG. 4B, the second key 12 is fitted into a key groove 30
formed in a thrust surface 6A of the shaft bearing 6 facing the orbiting scroll 3.
In the shaft bearing 6, a pair of key grooves 30 corresponding to the pair of second
keys 12 (FIG. 3) are formed.
[0049] The second key 12 slides in the key groove 30 in the radial direction with a predetermined
stroke.
[0050] The direction in which the first key 11 can slide along the key groove 20 (the direction
D1 in FIG. 3) and the direction in which the second key 12 can slide along the key
groove 30 (the direction D2 in FIG. 3) are orthogonal to each other.
[0051] When a rotary force of the rotating shaft 5 (FIG. 2) is transmitted to the orbiting
scroll 3 through the eccentric pin 5A, the first key 11 slides along the key groove
20 in the direction D1, while the second key 12 slides along the key groove 30 in
the direction D2, causing the Oldham link 10 as a whole sliding in the direction D2.
Thus, the orbiting scroll 3 revolves relative to the fixed scroll 2 while tracing
a predetermined trajectory without rotating.
[0052] FIGS. 5A and 5B show the key groove 20 formed in the end plate 3A of the orbiting
scroll 3 as seen from the rear surface side (lower surface side) of the end plate
3A.
[0053] The key groove 20 is depressed to a predetermined depth from the rear surface of
the end plate 3A of the orbiting scroll 3.
[0054] The key groove 20 extends a predetermined distance in the radial direction from an
outer peripheral edge 3B of the orbiting scroll 3 toward the center of the scroll.
An outer peripheral-side end 20A of the key groove 20 opens to the outside of the
orbiting scroll 3. An inner peripheral-side end 20B of the key groove 20 has an arc
shape in a plan view.
[0055] An inner periphery 201 of the key groove 20 stands vertically on a flat bottom 202
of the key groove 20.
[0056] While the orbiting scroll 3 makes one revolution, the first key 11 (indicated by
the two-dot dashed line in FIG. 5B) reciprocates in the radial direction along the
wall 21 of the key groove 20 by being guided by the key groove 20. As shown in FIG.
4A, the first key 11 shifts in a reciprocating manner within a range Rg1 of the key
groove 20 from the outer peripheral-side end 20A to the vicinity of the inner peripheral-side
end 20B.
[0057] The first key 11 slides along one surface 21 of two opposite surfaces 21, 22 (FIG.
5B) of the key groove 20 that is determined by the direction of rotation of the orbiting
scroll 3. The surface along which the first key 11 slides will be referred to as the
wall 21 of the key groove 20.
[0058] As shown in FIG. 5A, it is preferable that the wall 21 of the key groove 20 be formed
by a liner 23 that is discrete (distinct) from the end plate 3A of the orbiting scroll
3.
[0059] Since the orbiting scroll 3 that is the base material of the key groove 20 and the
liner 23 are discrete, a material different from the base material of the key groove
20, preferably a wear-resistant hard material, can be used for the liner 23. It is
preferable that the liner 23 be harder than the base material of the key groove 20,
at least at a predetermined thickness from the surface (sliding surface). An appropriate
surface processing or surface treatment can increase the surface hardness of the liner
23.
[0060] Moreover, since the sliding surface (wall 21) is formed by the liner 23 that is discrete
from the base material of the key groove 20, crowning processing or polishing processing,
to be described later, can be more easily performed on the liner 23 than on the base
material of the key groove.
[0061] The above description also applies to a liner 28 (FIG. 6) disposed in the key groove
30.
[0062] FIG. 6 shows the key groove 30 formed in the shaft bearing 6. The surface along which
the second key 12 (FIG. 2 and FIG. 3) slides will be referred to as a wall 31 of the
key groove 30.
[0063] The key groove 30 is depressed from the thrust surface 6A of the shaft bearing 6.
An outer peripheral-side end 30A and an inner peripheral-side end 30B of the key groove
30 have arc shapes in a plan view.
[0064] While the orbiting scroll 3 makes one revolution, the second key 12 (FIG. 2 and FIG.
3) reciprocates in the radial direction along the wall 31 of the key groove 30 by
being guided by the key groove 30. The second key 12 shifts in a reciprocating manner
within a range Rg2 (FIG. 4B) of the key groove 30 between the inner peripheral-side
end 30B and the outer peripheral-side end 30A.
[0065] The ranges Rg1, Rg2 (FIG. 4) within which the first key 11 and the second key 12
slide in the key grooves 20, 30 are merely examples, and the ranges of sliding are
determined as appropriate along the walls 21, 31 of the key grooves 20, 30.
[0066] The ranges Rg1, Rg2 of sliding in the key grooves 20, 30 and whether the outer peripheral-side
end of the key groove is opened are determined in connection with the strokes of the
first key 11 and the second key 12.
<First Embodiment>
[0067] Specific configurations of the first and second keys 11, 12 and the key grooves 20,
30 will be described below.
[0068] The first embodiment mainly features the shape (an offset portion 21A to be described
later) of the wall 21 of the key groove 20 and a surface roughness Ra of the key groove
30. Both features are intended to reduce wear of the keys 11, 12 and the key grooves
20, 30.
[0069] As described above, the lubricating oil is supplied from the storage part inside
the housing 8 to the upper end of the rotating shaft 5, but it is difficult to sufficiently
supply the lubricating oil from the upper end of the rotating shaft 5 to the Oldham
link 10 through the gaps among the end plate 3A of the orbiting scroll 3, the thrust
plate (not shown), the thrust surface 6A of the shaft bearing 6, etc.
[0070] In particular, it is difficult to sufficiently form an oil film during low-speed
operation, as the velocity of the lubricating oil flowing along the sliding surface
is low and thus the pressure of the lubricating oil according to a wedge effect of
the lubricating oil is low.
[0071] Moreover, as for the key groove 20, the lubricating oil is difficult to retain at
the outer peripheral-side end 20A that is open.
[0072] Thus, it is important to reduce wear even when the keys 11, 12 of the Oldham link
10 come in contact respectively with the walls 21, 31 of the key grooves 20, 30.
[0073] First, a state of wear of a key groove 40 (FIG. 7) that was checked to determine
the shape of the wall 21 of the key groove 20 will be described.
[0074] A durability test equivalent to a predetermined time of use (operation) was conducted
on a scroll compressor that was not used except in trial operation etc. for operation
check. FIG. 7C schematically shows the resulting surface shape of a wall 41 of the
key groove 40 that has worn from its initial state (before the durability test).
[0075] The horizontal axis of FIG. 7C corresponds to the sliding direction indicated by
the arrow in FIG. 7B. As shown in FIG. 7C, the depth of wear (amount of wear) of the
wall 41 increases from an inner peripheral-side end 40B of the key groove 40 toward
an outer peripheral-side end 40A thereof that is open. The broken line shown in FIG.
7C corresponds to the flat surface of the wall 41 in its initial state.
[0076] The increase in amount of wear of the wall 41 toward the open end (outer peripheral-side
end 40A) of the key groove 40 is mainly attributable to the fact that, at the side
of the open end (outer peripheral-side end 40A) of the key groove 40, the first key
11 shifts in a reciprocating manner while being inclined relative to the wall 41 as
shown in FIG. 7A.
[0077] The amount of wear is largest at the open end (edge) of the key groove 40 at which
the inclination angle of the first key 11 is largest.
[0078] In this embodiment, as shown in FIG. 5B, a part of the wall 21 is gradually offset
from a reference surface 210 on the basis of the profiling data on the surface shape
of the wall 41 shown in FIG. 7C. The reference surface 210 is an assumed flat surface
in the surface of the wall 21, and corresponds to the flat surface of the wall 41
in its initial state indicated by the broken line in FIG. 7C.
[0079] The wall 21 has the offset portion 21A that is further offset from the reference
surface 210 while extending toward the outer peripheral-side end 20A. An amount of
offset Of of the offset portion 21A from the reference surface 210 is, for example,
up to approximately 15 to 20 µm. The offset portion 21A shown in FIG. 5B has an exaggerated
amount of offset. The offset portion 21A is not shown in FIG. 5A.
[0080] The shaded part in FIG. 5B does not exist. The surface of the offset portion 21A
is denoted by reference sign 21S.
[0081] The shape of the surface 21S of the offset portion 21A simulates the surface shape
(FIG. 7C) of the wall 21 that has worn through use. The offset portion 21A recedes
gradually from the reference surface 210 at a smooth and gentle gradient.
[0082] As shown in FIG. 5B, the wall 21 including the offset portion 21A is formed by the
liner 23 provided in the end plate 3A. The liner 23 has a rectangular plate-like shape,
and is disposed in a recess 3C that is formed in the end plate 3A so as to be depressed
from the inner periphery 201 of the key groove 20. The surface of the liner 23 and
the surface of the inner periphery 201 are flush and continuous with each other. The
plate thickness of the liner 23 can be set as appropriate.
[0083] Machining such as crowning processing is performed on the liner 23 as a single part
to form the offset portion 21A therein, and the liner 23 is disposed in the recess
3C of the end plate 3A. The liner 23 is integrated with the end plate 3A by an appropriate
method. The liner 23 can be integrated with the end plate 3A, for example, by casting
the end plate 3A with the liner 23 disposed inside a casting mold of the end plate
3A. Alternatively, the liner 23 can be fastened to the end plate 3A.
[0084] The effect achieved by forming the offset portion 21A in the wall 21 before the start
of use will be described.
[0085] As shown in FIG. 5A, when the first key 11 is inclined relative to the wall 21, a
side surface 11S of the first key 11 comes in contact with the gently curved offset
portion 21A (FIG. 5B). Thus, the first key 11 and the wall 21 (liner 23) of the key
groove 20 can come in surface contact with each other, so that sliding friction is
suppressed even at the edge of the outer peripheral-side end 20A of the key groove
20.
[0086] As a result, significant wear typically occurring at an initial stage of use is prevented
and the wall 21 of the key groove 20, and the side surface 11S of the first key 11
are quickly adapted to each other, allowing the first key 11 to slide stably with
low friction.
[0087] In this embodiment, the surface roughness Ra of the wall 31 of the key groove 30
(FIG. 6) also simulates the surface state of the wall 41 (FIG. 7) that has worn through
use, and the surface roughness Ra of the wall 31 of the key groove 30 is 0.2 µm or
less.
[0088] Since the surface roughness Ra of the existing wall 41 (FIG. 7) exceeds 0.2 µm, when
the unused scroll compressor 1 starts to be used, the surface roughness Ra of the
wall 41 decreases gradually from its initial state due to sliding friction between
the second key 12 and the wall 41. Thereafter, the surface roughness Ra of the wall
41 stabilizes when the wall 41 of the key groove 30 and the side surface of the second
key 12 have been adapted to each other. The surface roughness Ra of the wall 41 at
this point is 0.2 µm or less.
[0089] On the basis of this wear process of the wall 41, the surface roughness Ra of the
wall 31 (FIG. 6) of the key groove 30 in this embodiment is set to 0.2 µm or less.
[0090] Although setting the surface roughness Ra of the side surface of the key 12 sliding
along the wall 31 of the key groove 30 to 0.2 µm or less can also achieve the same
effect as setting the surface roughness Ra of the wall 31 to 0.2 µm or less, in view
of the processing cost and time, the surface roughness Ra of the wall 31 of the key
groove 30 is set to 0.2 µm or less.
[0091] It is preferable that the wall 31 be formed by the liner 28 that is discrete from
the base material of the key groove 30. Performing polishing processing on the liner
28 as a single part can set the surface roughness (Ra) of the surface (sliding surface)
of the liner 28 forming the wall 31 to a predetermined surface roughness.
[0092] If the surface roughness Ra of the wall 31 is set to 0.2 µm or less before the start
of use of the scroll compressor 1, the wall 31 of the key groove 30 and the side surface
of the second key 12 are quickly adapted to each other, so that solid-to-solid contact
can be reduced even when the oil film is thin due to the low surface roughness. Thus,
significant wear typically occurring at an initial stage is avoided, and the side
surface of the second key 12 slides along the wall 31 of the key groove 30 stably
with low friction.
[0093] As has been described above, wear occurring at an initial stage of use can be suppressed
by forming the offset portion 21A for the first key 11 of the Oldham link 10 and the
key groove 20, and by setting the surface roughness Ra for the second key 12 and the
key groove 30. Accordingly, wear of the keys 11, 12 of the Oldham link 10 and the
walls 21, 31 of the key grooves 20, 30 can be reduced, and power loss due to friction
can also be suppressed.
[0094] According to this embodiment, it is possible to suppress wear of the keys 11, 12
and the key grooves 20, 30, even under severe lubricating conditions, by forming the
offset portion 21A and setting the surface roughness Ra. It is therefore possible
to remove operational restrictions, such as increasing the rotation speed to prevent
a lack of lubricating oil after continuous low-speed operation.
[0095] It is preferable that a coating be formed using a solid lubricant on the sliding
parts of the Oldham link 10 to which sufficient lubricating oil is difficult to supply
and which is thus likely to be subject to sever lubricating conditions.
[0096] For example, a solid lubricant obtained by dispersing powder of polytetrafluoroethylene
(PTFE) in an epoxy resin or a polyimide resin or the like can be used to form a coating
on the side surfaces of the keys 11, 12 and the surfaces (liner surfaces) of the walls
21, 31 of the key grooves 20, 30. The coating is not shown in the drawings.
[0097] In the case where a coating of a solid lubricant is formed on the offset portion
21A, it is preferable that the wall 21 be machined to a larger amount of offset than
a desired amount of offset with the thickness of the coating taken into account. In
that case, the final amount of offset is determined by the surface of the coating
of the solid lubricant.
[0098] In the case where a coating of a solid lubricant is formed in a portion of the wall
21 for which the surface roughness Ra is set to 0.2 µm or less, the surface roughness
Ra of the solid lubricant coating adhering to the surface of the base material is
machined to 0.2 µm or less. The solid lubricant coating can be polished, for example,
by mechanical polishing with a grinder or by spraying abrasive grains, or by chemical
polishing of dissolving the coating using a chemical.
[0099] In this embodiment, the presence of the offset portion 21A or the setting of the
surface roughness Ra prevents significant wear at an initial stage of use, so that
the coatings of a solid lubricant applied on the wall 21 and the wall 31 remain without
wearing. These coatings can be maintained to secure wear resistance.
[0100] The coating of a solid lubricant can be formed on all the keys 11, 12 and the key
grooves 20, 30 or on some of these keys and key grooves selected according to the
lubricating conditions etc.
[0101] As the Oldham link 10 slides over the end plate 3A and the shaft bearing 6 while
restricting rotation of the orbiting scroll 3, a coating of a solid lubricant may
be applied on the entire sliding surface of the Oldham link 10 to improve the lubricity
of the entire Oldham link 10.
<Modified Example of First Embodiment>
[0102] It is preferable that the surface roughness Ra of the wall 21 of the key groove 20
be set to 0.2 µm or less in addition to the offset portion 21A (FIG. 5B) being formed
in the wall 21.
[0103] It is preferable that a durability test with varied surface roughness Ra be conducted
to appropriately determine the surface roughness Ra.
[0104] In FIG. 8, a relation between the depth of wear (amount of wear) at the end of the
key 11 on the outer peripheral side and the surface roughness Ra of the wall 21 after
a durability test is plotted with black rhombuses. The depth of wear shown is an average
value of a plurality of measured values. The amount of wear and the surface roughness
Ra of the wall 21 of the key groove 20 correspond to the amount of wear and the surface
roughness Ra of the key 11.
[0105] As can be seen from FIG. 8, the lower the surface roughness Ra, the smaller the amount
of wear after the durability test.
[0106] With variation in measured value of multiple times of the test (measured values of
the depth of wear exceeding the average value are indicated by the straight line)
taken into account, the surface roughness Ra of the wall 21 needs to be 0.2 µm or
less to keep the depth of wear under the allowable value.
[0107] It is possible to more sufficiently reduce wear by providing the offset portion 21A
in the wall 21 and setting the surface roughness Ra of the wall 21 to 0.2 µm or less
before the start of use.
[0108] FIG. 9A shows another modified example of the first embodiment.
[0109] The wall 21 of the key groove 20 is provided with an offset portion 21B located in
the vicinity of the inner peripheral-side end 20B, in addition to the offset portion
21A located at the outer peripheral-side end 20A.
[0110] It is preferable that the offset portion 21B be gradually offset from the reference
surface 210 while extending toward the inner peripheral-side end 20B.
[0111] As with the offset portion 21A, the offset portion 21B shown in FIG. 9A has an exaggerated
amount of offset.
[0112] The shaded part in FIG. 9A does not exist. The surface of the offset portion 21A
is denoted by reference sign 21S and the surface of the offset portion 21B is denoted
by reference sign 21S'.
[0113] The shapes of the surfaces 21S, 21S' of the offset portions 21A, 21B simulate the
surface shape of the wall 21 that has worn through use.
[0114] As shown in FIG. 9B, in both an inward path and an outward path of the first key
11 that shifts in a reciprocating manner, an oil film 100 is formed between the first
key 11 and the wall 21 by the wedge effect occurring as the lubricating oil flows
into the gap between the first key 11 and the wall 21.
[0115] Here, at both ends of the wall 21 in the sliding direction, where the shifting velocity
of the first key 11 is low and a sufficient wedge effect is therefore difficult to
obtain, a sufficient oil film 100 is difficult to form. Then, compared with in a center
part of the wall 21, the amount of wear becomes larger at both ends of the wall 21
due to the sliding friction between the wall 21 and the first key 11 inclined relative
to the wall 21. Accordingly, the offset portions 21A, 21B are formed in advance at
the outer peripheral-side end 20A and in the vicinity of the inner peripheral-side
end 20B of the wall 21.
[0116] The amount of offset Of of the offset portion 21A from the reference surface 210
corresponds to the amount of wear on the outer peripheral side (radially outer side)
of the wall 21, while an amount of offset Of of the offset portion 21B from the reference
surface 210 corresponds to the amount of wear on the inner peripheral side (radially
inner side) of the wall 21.
[0117] In the configuration shown in FIG. 9A, on the basis of the fact that the key groove
20 wears easily especially at the side of the open end (outer peripheral-side end
20A), the amount of offset Of of the offset portion 21A is set to be larger than the
amount of offset Of of the offset portion 21B.
[0118] According to the configuration shown in FIGS. 9A and 9B, the offset portions 21A,
21B are formed with wear through use taken into account, which makes it possible to
reduce wear by preventing significant wear typically occurring at an initial stage.
[0119] Forming the offset portion simulating wear before use is also applicable to the wall
31 (FIG. 6) of the key groove 30 along which the second key 12 slides.
[0120] The position and the amount of offset of the offset portion formed in the wall 31
can be determined as appropriate on the basis of the stroke and the sliding conditions
of the second key 12.
[0121] For example, it is possible to form an offset portion in a region of the wall 31
corresponding to the range Rg2 (FIG. 4) of sliding of the second key 12 so as to be
symmetrical with respect to the center of the range Rg2.
<Second Embodiment>
[0122] Next, a second embodiment of the present invention will be described with reference
to FIGS. 10A to 10C.
[0123] The second embodiment to a fifth embodiment feature structures for positioning the
liner in the key groove. The second embodiment to the fifth embodiment can be combined
as appropriate.
[0124] In the following, a liner disposed in the key groove 20 in which the first key 11
slides will be taken as an example, but the configurations described below are also
applicable to a liner disposed in the key groove 30 in which the second key 12 slides.
[0125] At least one of crowning processing of forming the offset portion 21A or the offset
portion 21B and machining of setting the surface roughness to 0.2 µm or less is performed
on the surface of a liner 24 that is disposed so as to be flush with the inner periphery
201 of the key groove 20 as shown in FIG. 10A. The offset portion is not shown in
FIG. 10.
[0126] The above description is also applicable to the liners (to be described later) shown
in FIG. 11 to FIG. 16.
[0127] In the configuration shown in FIG. 10A, a protrusion 241 provided on the liner 24
is fitted in a recess 211 formed in the inner periphery 201 of the key groove 20.
The recess 211 is depressed farther than a surface 3E on which a plate-like main body
240 of the liner 24 is disposed. The protrusion 241 of the liner 24 is fitted between
walls 211A, 211B of the recess 211 that are separated from each other in the sliding
direction.
[0128] In this specification, the direction in which the first key 11 slides along the radial
direction of the rotating shaft 5 will be referred to as "the sliding direction".
The direction in which the second key 12 slides along the radial direction of the
rotating shaft 5 will be also referred to as "the sliding direction".
[0129] In the configuration shown in FIG. 10A, the liner 24 and the inner periphery 201
of the key groove 20 are fitted with each other through engagement between the recess
211 and the protrusion 241, and thereby the liner 24 is positioned in the orbiting
scroll 3 in the sliding direction. Thus, the liner 24 can be prevented from slipping
or detaching in the sliding direction from the inner periphery 201 of the key groove
20.
[0130] Other than the configuration shown in FIG. 10A, for example, the configurations shown
in FIG. 10B and FIG. 10C can also be used to position the liner 24 in the key groove
20 by engagement fitting.
[0131] In FIG. 10B, the protrusion 241 of the liner 24 is located further on the radially
outer side than in FIG. 10A. The configuration of FIG. 10B is otherwise the same as
that of FIG. 10A.
[0132] In FIG. 10C, the recess 212 is formed at the outer peripheral-side end 20A as well
as in the vicinity of the inner peripheral-side end 20B of the inner periphery 201
of the key groove 20, and two protrusions 251, 251 protruding from a plate-like main
body 250 of a liner 25 toward the rear surface side are fitted inside the recesses
212, 212.
[0133] In the configurations shown in FIGS. 10A to 10C, the main bodies 240, 250 of the
liners 24, 25 extend to the open end (outer peripheral-side end 20A) of the key groove
20, so that the sliding friction between the first key 11 and the key groove 20 at
the edge of the key groove 20 can be reduced.
<Third Embodiment>
[0134] Next, the third embodiment of the present invention will be described with reference
to FIG. 11.
[0135] As shown in FIG. 11, a liner 26 of the third embodiment is formed in a U-shape and
disposed along the entire inner periphery 201 of the key groove 20.
[0136] The liner 26 has a plate-like part 261 along which the first key 11 slides, a plate-like
part 262 facing the plate-like part 261, and a coupling part 263 coupling together
the plate-like parts 261, 262 at the inner peripheral-side end 20B of the key groove
20.
[0137] In the configuration shown in FIG. 11, the liner 26 is positioned in the key groove
20 without a protrusion or a recess formed in the liner 26 or the key groove 20.
[0138] The width of the liner 26 in the direction connecting the plate-like parts 261, 262
to each other is set to be larger than the width of the key groove 20, so that the
liner 26 deflects so as to be compressed inside the key groove 20, and is fixed to
the key groove 20 by an elastic force.
[0139] Thus, the liner 26 can be prevented from slipping from the inner periphery 201 of
the key groove 20 in the sliding direction or the width direction of the liner 26,
or the liner 26 can be prevented from detaching from the key groove 20.
[0140] The second embodiment and the third embodiment can be combined as appropriate.
[0141] In FIG. 12A, a protrusion 264 formed on the U-shaped liner 26 is fitted inside the
recess 212 formed in the inner periphery 201 of the key groove 20.
[0142] In the configuration of FIG. 12B, which is similar to that of FIG. 12A, a protrusion
265 of the liner 26 is fitted inside a recess 213 formed in a region of the inner
periphery 201 of the key groove 20 where the first key 11 slides.
[0143] In FIG. 13, a protrusion 214 formed on the inner periphery 201 of the key groove
20 is fitted into a recess 266 formed in the U-shaped liner 26.
[0144] In the configurations shown in FIGS. 12A, 12B, and 13, it is not necessary to fix
the liner 26 inside the key groove 20 by an elastic force or interference fitting.
According to the engagement fitting between the U-shaped liner 26 and the inner periphery
201 of the key groove 20, the liner 26 can be prevented from slipping from the inner
periphery 201 of the key groove 20 in the sliding direction or the width direction,
or the liner 26 can be prevented from detaching from the key groove 20.
<Fourth Embodiment>
[0145] Next, the fourth embodiment of the present invention will be described with reference
to FIGS. 14A and 14B.
[0146] In the configuration shown in FIG. 14A, a liner groove 29 that receives a peripheral
edge 271 of a liner 27 is formed in the bottom 202 of the key groove 20.
[0147] The entire peripheral edge 271 of the U-shaped liner 27 is fitted inside the U-shaped
liner groove 29 that is formed at the root of the inner periphery 201 of the key groove
20.
[0148] According to this configuration, the liner 27 is positioned in both the sliding direction
and the width direction in the key groove 20 of the orbiting scroll 3 by fitting through
engagement between the liner groove 29 (recess) and the peripheral edge 271 (protrusion)
of the liner 27.
[0149] As shown in FIG. 14B, a J-shaped liner 27' can also be adopted.
[0150] The liner 27' has a plate-like part 291 disposed in the region of the inner periphery
201 where the first key 11 slides, and a curved part 292 that continues to the inner
peripheral edge of the plate-like part 291 and curves along the arc-shaped inner peripheral-side
end 20B.
[0151] As the plate-like part 291 is fitted into the straight part of the liner groove 29,
the liner 27' is positioned in the key groove 20 in the plate thickness direction,
and as the curved part 292 is fitted in the curved part of the liner groove 29, the
liner 27' is positioned in the key groove 20 in the sliding direction.
[0152] The configuration of the fourth embodiment can also be used to position the liner
28 (FIG. 6) along which the second key 12 slides. In that case, for example, the peripheral
edge of the liner 28 is fitted into a liner groove formed in the bottom of the key
groove 30. Then, the liner 28 is positioned in both the plate thickness direction
and the sliding direction by fitting through engagement between the peripheral edge
of the liner 28 and the liner groove.
<Fifth Embodiment>
[0153] Next, the fifth embodiment of the present invention will be described with reference
to FIG. 15.
[0154] A liner 50 shown in FIG. 15 has a bottom 51A disposed on the bottom 202 of the key
groove 20, and a U-shaped wall 51B standing on the bottom 51A and disposed on the
inner periphery 201 of the key groove 20.
[0155] The bottom 51A of the liner 50 has a width larger than the width of the bottom 202
of the key groove 20, and is pressed onto the bottom 202 of the key groove 20 to form
the bottom surface of the key groove 20.
[0156] At least one of crowning processing for forming an offset portion (not shown) and
machining for setting the surface roughness to 0.2 µm or less is performed on the
inner surface (sliding surface) of the wall 51B.
[0157] The wall 51B may be formed in a J-shape like the liner 27' of FIG. 14B, or may be
formed in a plate-like shape like the liner 23 shown in FIG. 5.
[0158] As the bottom 51A is pressed and fixed in the key groove 20, the liner 50 can be
prevented from slipping from the inner periphery 201 of the key groove 20 in the sliding
direction or the width direction, or the liner 50 can be prevented from detaching
from the key groove 20.
[0159] The configuration of the fifth embodiment can also be used to position the liner
28 (FIG. 6) along which the second key 12 slides.
<Sixth Embodiment>
[0160] Next, a sixth embodiment of the present invention will be described with reference
to FIG. 16.
[0161] In the sixth embodiment, a liner that is allowed to shift in the sliding direction
of the key is interposed between the key and the wall of the key groove.
[0162] FIG. 16 shows the key groove 30 in which the second key 12 is disposed.
[0163] In the key groove 30, a plate-like liner 52 forming the wall 31 along which the second
key 12 slides is disposed.
[0164] The liner 52 is housed in a liner housing part 53 formed in the shaft bearing 6.
[0165] As the dimension of the liner housing part 53 is larger than the dimension of the
liner 52 in the sliding direction, there is a space Sp inside the liner housing part
53 that allows the liner 52 to shift in the sliding direction of the second key 12.
[0166] When the second key 12 comes in contact with the liner 52 (wall 31) and shifts in
the sliding direction while retaining the liner 52 by a friction force, the liner
52 also shifts inside the liner housing part 53 (see the arrows).
[0167] According to the sixth embodiment, the second key 12 shifts in a reciprocating manner
along with the liner 52, so that the distance the second key 12 and the liner 52 slide
and shift relative to each other can be reduced, and thus wear of the second key 12
and the liner 52 can be reduced.
[0168] As the rear surface of the liner 52 slides over an inner periphery 301 of the key
groove 30, the friction force is divided into a friction force between the second
key 12 and the liner 52 and a friction force between the liner 52 and the inner periphery
301. Thus, wear of each of the second key 12, the liner 52, and the inner periphery
301 (shaft bearing 6) is suppressed.
[0169] As shown in FIG. 16, to prevent the key 12 from shifting beyond the ends of the liner
52, the following relation needs to be satisfied:

where d is the stroke of the key 12, Ln is the dimension of the liner housing part
53 that is the movable range of the liner 52, and Sp is the length of the space inside
the liner housing part 53.
[0170] According to this relation, it is possible to shift the liner 52 along with the key
12 while keeping the key 12 between the left end and the right end of the liner 52.
[0171] In the sixth embodiment, it is not absolutely necessary to form an offset portion
in the liner 52 or set the surface roughness of the liner 52 to 0.2 µm or less. As
with the liner 23 etc. described above, at least one of crowning processing for forming
the offset portion and machining for setting the surface roughness to 0.2 µm or less
performed on the liner 52 can contribute to further wear reduction.
<Seventh Embodiment>
[0172] Next, a seventh embodiment of the present invention will be described with reference
to FIG. 17 and FIG. 18.
[0173] The seventh embodiment is configured so that a liner swings to follow the posture
of the key.
[0174] FIG. 17A shows the key groove 20 in which the first key 11 is disposed.
[0175] In the key groove 20, a plate-like liner 54 forming the wall 21 along which the first
key 11 slides is disposed.
[0176] The liner 54 is housed in a recess 55 formed in the orbiting scroll 3.
[0177] A support portion 551 protruding in an arc shape in a plan view is formed on the
wall of the recess 55 located on the rear surface side of the liner 54. The support
portion 551 is located in the vicinity of the inner peripheral-side end 20B in the
wall of the recess 55. The liner 54 supported by the support portion 551 is swingable
within the range of a clearance CL between the liner 54 and the wall of the recess
55.
[0178] FIG. 17B shows an example in which a support portion 541 is formed not in the recess
55 but on the rear surface side of the liner 54. The liner 54 supported by the support
portion 541 inside the recess 55 is swingable within the range of the clearance CL
between the liner 54 and the wall of the recess 55.
[0179] As shown in FIG. 18, when the first key 11 shifts in a reciprocating manner, the
liner 54 swings (inclines) to an angle following the posture of the first key 11.
In both the inward path and the outward path of the first key 11, the liner 54 swings,
around the support portion 541 (or 551) as a supporting point, between an angle at
which the liner 54 is parallel to the axis of the key groove 20 and an angle at which
the outer peripheral-side end of the liner 54 comes in contact with the wall of the
recess 55.
[0180] As a result, the side surface 11S of the first key 11 comes in surface contact with
the liner 54, so that the first key 11 slides over the surface of the liner 54 stably
with low friction.
[0181] According to the seventh embodiment, the liner 54 swings to follow the posture of
the first key 11, so that the sliding friction between the first key 11 and the liner
54 can be suppressed, and thus wear of the first key 11 and the liner 54 can be reduced.
[0182] In the seventh embodiment, it is not absolutely necessary to form an offset portion
in the liner 54 or set the surface roughness of the liner 54 to 0.2 µm or less. As
with the liner 23 etc. described above, at least one of crowning processing for forming
an offset portion and machining for setting the surface roughness to 0.2 µm or less
performed on the liner 54 can contribute to further wear reduction.
<Eighth Embodiment>
[0183] Next, an eighth embodiment of the present invention will be described with reference
to FIG. 19.
[0184] In the eighth embodiment, the lubricating oil that is supplied to the periphery of
the eccentric pin 5A through the oil supply path 5C (FIG. 2) inside the rotating shaft
5 is supplied to the sliding surfaces through the inside of the liner.
[0185] As shown in FIG. 2, the eccentric pin 5A is connected to the inside of a boss 3F
of the orbiting scroll 3 through the bearing 5B. The eccentric pin 5A, the bearing
5B, and the boss 3F are disposed inside a recess 6C formed around the rotating shaft
5 in the shaft bearing 6.
[0186] The inside of the recess 6C serves as an oil sump where the lubricating oil is accumulated.
A pressure difference is provided between the atmosphere inside the recess 6C and
the atmosphere outside the recess 6C, so that the lubricating oil inside the recess
6C is supplied to the outside of the recess 6C according to the pressure difference.
[0187] In the following, a liner disposed in the key groove 20 in which the first key 11
slides will be taken as an example, but the configurations described below are also
applicable to the liner disposed in the key groove 30 in which the second key 12 slides.
[0188] As shown in FIGS. 19A and 19B, a liner 56 of this embodiment is a member that is
attached to the orbiting scroll 3 and constitutes a part of the key groove 20.
[0189] Processing for forming an offset portion or processing for setting the surface roughness
to 0.2 µm or less is performed on the surface of the liner 56 that forms the wall
21 along which the first key 11 slides.
[0190] As shown in FIGS. 19B and 19C, an oil path 57 through which the lubricating oil flows
is formed by the key groove 20 and the liner 56.
[0191] The oil path 57 has a first path 571 extending in the sliding direction on the rear
side of the liner 56, and a plurality of second paths 572 extending from the first
path 571 in the plate thickness direction of the liner 56 and reaching the sliding
surface (wall 21) of the liner 56.
[0192] As shown in FIG. 19B, the first path 571 is formed between a groove 571C formed in
the rear surface of the liner 56 and the wall (FIG. 19A) of the recess 3C in which
the liner 56 is disposed.
[0193] A base end 571A of the first path 571 communicates with the inside of the recess
6C (FIG. 2) where the lubricating oil is accumulated.
[0194] The plurality of second paths 572 are disposed at intervals in the sliding direction
between the base end 571A and a leading end 571B of the first path 571, and each open
in the surface of the liner 56.
[0195] During operation of the scroll compressor 1, the lubricating oil inside the recess
6C is forcibly supplied through the oil path 57 to the sliding surfaces of the first
key 11 and the key groove 20 (liner 56) on the basis of the pressure difference between
the inside and the outside of the recess 6C. Under the pressure of the lubricating
oil jetting out of the second paths 572 opening in the surface of the liner 56 along
which the first key 11 slides, the first key 11 floats from the surface of the liner
56, and an oil film is formed between the first key 11 and the liner 56.
[0196] According to this embodiment, the amount of lubricating oil supplied to the key groove
20 is increased by the lubricating oil flowing through the oil path 57, and a thick
oil film is formed between the first key 11, floating on the lubricating oil jetting
out of the oil path 57, and the wall 21 of the key groove 20. Thus, solid-to-solid
contact is reduced, which can contribute to the reduction of wear of the first key
11 and the wall 21 (liner 56) of the key groove 20.
[0197] According to the eighth embodiment, it is possible to sufficiently reduce wear by
supplying oil to the sliding surfaces through the oil path 57, in addition to forming
an offset portion in the liner 56 or setting the surface roughness of the liner 56
to 0.2 µm or less.
[0198] The oil path 57 can be modified as appropriate, provided that the oil path 57 provides
communication between the inside of the recess 6C and the wall 21 of the key groove
20.
[0199] For example, the groove constituting the first path 571 can also be formed in the
wall of the recess 3C located on the rear surface of the liner 56, instead of in the
liner 56.
[0200] As shown in FIG. 19D, the first path 571 can also be formed inside the liner 56.
[0201] The configuration of the oil path 57 in the eighth embodiment is workable without
the precondition of processing for forming an offset portion in the liner 56 or processing
for setting the surface roughness of the liner 56 to 0.2 µm or less. In other words,
supplying oil to the sliding surfaces through the oil path 57 can contribute to wear
reduction.
[0202] The present invention is not limited to the above embodiments; the configurations
presented in the above embodiments can be selectively adopted or changed as appropriate
into other configurations within the gist of the present invention.
[0203] The Oldham link according to the present invention can also be applied to devices,
other than scroll compressors, that include a mechanism for converting a turning motion
of a member, which is eccentrically connected to a rotating shaft and turned along
with the rotating shaft, into a revolving motion while restricting rotation of that
member.