U.S. patent application number 15/038878 was filed with the patent office on 2017-01-05 for scroll compressor.
The applicant listed for this patent is DAIKIN INDUSTRIES, LTD.. Invention is credited to Takashi UEKAWA.
Application Number | 20170002816 15/038878 |
Document ID | / |
Family ID | 53198673 |
Filed Date | 2017-01-05 |
United States Patent
Application |
20170002816 |
Kind Code |
A1 |
UEKAWA; Takashi |
January 5, 2017 |
SCROLL COMPRESSOR
Abstract
A scroll compressor includes a casing with an oil reservoir,
fixed and movable scrolls, a crank shaft, and a housing having an
upper bearing rotatably supporting the crank shaft. The crank shaft
has an oil feed path and the housing has a crank chamber. An outer
peripheral surface of the crank shaft has an annular groove, and a
spiral groove. The housing has a bearing back-face passage
connecting the crank chamber and the annular groove. If no oil is
fed from the oil reservoir to the sliding surface of the crank
shaft through the oil feed path during rotation of the crank shaft,
oil in the crank chamber is fed to the upper bearing from the crank
chamber through the bearing back-face passage and the annular
groove due to a pump effect of the spiral groove.
Inventors: |
UEKAWA; Takashi; (Sakai-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIKIN INDUSTRIES, LTD. |
Osaka-shi, Osaka |
|
JP |
|
|
Family ID: |
53198673 |
Appl. No.: |
15/038878 |
Filed: |
December 1, 2014 |
PCT Filed: |
December 1, 2014 |
PCT NO: |
PCT/JP2014/005993 |
371 Date: |
May 24, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 29/023 20130101;
F04C 29/026 20130101; F04C 18/0215 20130101; F04C 23/008 20130101;
F04C 2240/50 20130101; F04C 2240/60 20130101; F04C 2240/809
20130101; F04C 29/02 20130101 |
International
Class: |
F04C 29/02 20060101
F04C029/02; F04C 18/02 20060101 F04C018/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 29, 2013 |
JP |
2013-248126 |
Claims
1. A scroll compressor comprising: a casing provided with an oil
reservoir at a bottom; a fixed scroll and a movable scroll housed
in the casing; a crank shaft having an upper end portion slidably
connected to a boss on a back face of the movable scroll; and a
housing arranged under the movable scroll and having an upper
bearing which rotatably supports the crank shaft, the crank shaft
being provided with an oil feed path arranged and configured to
feed oil in the oil reservoir to a sliding surface between the boss
and the upper bearing, the housing being provided with a crank
chamber formed by a recessed portion of the housing closer to a top
surface thereof to house the boss of the movable scroll, the crank
chamber being configured to accumulate oil fed to a sliding surface
of the crank shaft through the oil feed path, the crank shaft being
provided, on an outer peripheral surface thereof, with an annular
groove formed at a lower position of a sliding surface with the
upper bearing and extending in a circumferential direction of the
crank shaft to collect oil fed to the upper bearing, and a spiral
groove connecting the crank chamber and the annular groove to
transfer oil collected in the annular groove to the crank chamber,
the housing being provided with a bearing back-face passage formed
at a position closer to a back face of the upper bearing than to a
front face, the bearing back-face passage connecting the crank
chamber and the annular groove, and in an event in which no oil is
fed from the oil reservoir to the sliding surface of the crank
shaft through the oil feed path during rotation of the crank shaft,
the oil accumulated in the crank chamber being fed to the upper
bearing from the crank chamber through the bearing back-face
passage and the annular groove due to a pump effect of the spiral
groove.
2. The scroll compressor of claim 1, wherein in a normal operation
in which the oil is fed from the oil reservoir to the sliding
surface of the crank shaft through the oil feed path, the oil
collected in the annular groove passes through the spiral groove
and the bearing back-face passage to be transferred to the crank
chamber.
3. The scroll compressor of claim 1, wherein an inner wall surface
of the crank chamber is provided with an auxiliary oil reservoir
recessed in a radial direction and arranged and configured to
accumulate oil together with the crank chamber.
4. The scroll compressor of claim 3, wherein the housing is
provided with an oil discharge passage having an upstream end open
to the inner wall surface of the crank chamber at a position spaced
from a bottom surface of the crank chamber by a predetermined
distance, and a downstream end open to an outside of the housing,
and the auxiliary oil reservoir is open to the inner wall surface
of the crank chamber at a position lower in height than the oil
discharge passage.
5. The scroll compressor of claim 2, wherein an inner wall surface
of the crank chamber is provided with an auxiliary oil reservoir
recessed in a radial direction and arranged and configured to
accumulate oil together with the crank chamber.
6. The scroll compressor of claim 5, wherein the housing is
provided with an oil discharge passage having an upstream end open
to the inner wall surface of the crank chamber at a position spaced
from a bottom surface of the crank chamber by a predetermined
distance, and a downstream end open to an outside of the housing,
and the auxiliary oil reservoir is open to the inner wall surface
of the crank chamber at a position lower in height than the oil
discharge passage.
Description
TECHNICAL FIELD
[0001] The present invention relates to a scroll compressor.
BACKGROUND ART
[0002] Rotary compressors in which lubricating oil is continuously
supplied to a gap between a crank shaft and a bearing to achieve
smooth rotation of the crank shaft with respect to the bearing have
been known (see, e.g., Patent Document 1). Specifically, this crank
shaft includes an oil feed path through which the lubricating oil
accumulated in the bottom of the casing is sucked up. The
lubricating oil which has passed through the oil feed path is fed
to the bearing gap.
[0003] However, the lubricating oil may sometimes be discharged to
the outside of the casing with a refrigerant gas compressed by a
compression mechanism. Thus, if an excessive oil discharge occurs
since a large amount of lubricating oil has been discharged to the
outside of the casing, the lubricating oil at the bottom of the
casing is depleted and oil shortage occurs. As a result, no
lubricating oil is fed to the bearing gap.
[0004] To avoid this, the rotary compressor disclosed in Patent
Document 1 is configured such that the lubricating oil flowing down
through a bearing gap is collected in an annular groove formed in a
crank shaft, and the lubricating oil collected in the annular
groove is transferred to a crank chamber through a bearing
back-face passage formed in a housing closer to the back face of
the bearing such that the lubricating oil is accumulated in the
crank chamber.
[0005] Thus, if the lubricating oil at the bottom of the casing is
depleted and supply of the lubricating oil to the bearing gap
through the oil feed path is stopped, the lubricating oil
accumulated in the crank chamber flows into the bearing gap due to
its own weight to achieve continuous lubrication of the sliding
portion between the crank shaft and the bearing.
CITATION LIST
Patent Document
[0006] Patent Document 1: Japanese Unexamined Patent Publication
No. 2012-097576
SUMMARY OF THE INVENTION
Technical Problem
[0007] However, in the known rotary compressors, the gap between
the crank shaft and the bearing is set to be very narrow. Thus, the
problem is that only a small amount of oil can flow, due to its own
weight, into the bearing gap from the crank chamber. This may lead
to unsatisfactory lubrication at the sliding portion between the
crank shaft and the bearing even in the event of the depletion of
the lubricating oil, since the lubricating oil accumulated in the
crank chamber cannot be effectively used.
[0008] In view of the foregoing, it is therefore an object of the
present invention to achieve continuous lubrication of a sliding
portion between a crank shaft and a bearing even in a situation in
which no oil is fed to a sliding surface of the crank shaft through
an oil feed path during rotation of the crank shaft.
Solution to the Problem
[0009] Aspects of the present disclosure are directed to a scroll
compressor which includes: a casing (11) provided with an oil
reservoir (17) at a bottom; a fixed scroll (40) and a movable
scroll (35) which are housed in the casing (11); a crank shaft (23)
having an upper end portion slidably connected to a boss (38) on a
back face of the movable scroll (35); and a housing (50) arranged
under the movable scroll (35) and having an upper bearing (62)
which rotatably supports the crank shaft (23). The present
disclosure provides the following solutions.
[0010] Specifically, a first aspect of the present disclosure is
characterized in that: the crank shaft (23) is provided with an oil
teed path (27) feeds oil in the oil reservoir (17) to a sliding
surface between the boss (38) and the upper bearing (62); the
housing (50) is provided with a crank chamber (54) which is a
recessed portion of the housing (50) closer to a top surface
thereof to house the boss (38) of the movable scroll (35), and the
crank chamber (54) being configured to accumulate oil fed to a
sliding surface of the crank shaft (23) through the oil feed path
(27); the crank shaft (23) is provided, on an outer peripheral
surface thereof, with an annular groove (24a) formed at a lower
position of a sliding surface with the upper bearing (62) and
extending in a circumferential direction of the crank shaft (23) to
collect oil fed to the upper bearing (62), and a spiral groove
(24b) connecting the crank chamber (54) and the annular groove
(24a) to transfer oil collected in the annular groove (24a) to the
crank chamber (54); the housing (50) is provided with a bearing
back-face passage (53a) formed at a position closer to a back face
of the upper bearing (62), the bearing back-face passage (53a)
connecting the crank chamber (54) and the annular groove (24a); and
in an event in which no oil is fed from the oil reservoir (17) to
the sliding surface of the crank shaft (23) through the oil feed
path (27) during rotation of the crank shaft (23), the oil
accumulated in the crank chamber (54) is fed to the upper bearing
(62) from the crank chamber (54) through the bearing back-face
passage (53a) and the annular groove (24a) due to a pump effect of
the spiral groove (24b).
[0011] According to the first aspect of the present disclosure, the
outer peripheral surface of the crank shaft (23) is provided with
an annular groove (24a) and a spiral groove (24b). The annular
groove (24a) collects the oil which has been fed to the upper
bearing (62). The oil collected in the annular groove (24a) passes
through the spiral groove (24b) to be transferred to the crank
chamber (54). The housing (50) is provided with a bearing back-face
passage (53a) at a position closer to the back face of the upper
bearing (62). The bearing back-face passage (53a) connects the
crank chamber (54) and the annular groove (24a).
[0012] This configuration allows continuous lubrication of the
sliding portion between the crank shaft (23) and the upper bearing
(62) even if oil shortage occurs and no oil is fed to the sliding
surface of the crank shaft (23) from the oil reservoir (17) through
the oil feed path (27) during rotation of the crank shaft (23).
[0013] Specifically, oil is not fed to the upper bearing (62)
through the oil feed path (27) if the remaining amount of oil
accumulated in the oil reservoir (17) is small. If the crank shaft
(23) continues to rotate in this oil shortage state, seizing
between the crank shaft (23) and the upper bearing (62) may
occur.
[0014] To avoid this, an aspect of the present disclosure is that
if oil shortage occurs and oil feed to the upper bearing (62)
through the oil feed path (27) is stopped, the oil accumulated in
the crank chamber (54) is fed to the upper bearing (62) from the
crank chamber (54) through the bearing back-face passage (53a) and
the annular groove (24a) due to a pump effect of the spiral groove
(24b). This allows continuous lubrication of the sliding portion
between the crank shaft (23) and the upper beating (62) even after
the oil shortage, as long as oil is accumulated in the crank
chamber (54). As a result, seizing between the crank shaft (23) and
the upper bearing (62) may be reduced.
[0015] A second aspect of the present disclosure is an embodiment
of the first aspect of the present disclosure. In the second
aspect, in a normal operation in which the oil is fed from the oil
reservoir (17) to the sliding surface of the crank shaft (23)
through the oil feed path (27), the oil collected in the annular
groove (24a) passes through the spiral groove (24b) and the bearing
back-face passage (53a) to be transferred to the crank chamber
(54).
[0016] According to the second aspect of the present disclosure,
the oil collected in the annular groove (24a) is transferred to the
crank chamber (54) not only through the spiral groove (24b), but
also through the bearing back-face passage (53a) in a normal
operation. The amount of oil that is transferred from the annular
groove (24a) to the crank chamber (54) may be increased
accordingly.
[0017] A third aspect of the present disclosure is an embodiment of
the first or second aspect of the present disclosure. In the third
aspect, an inner wall surface of the crank chamber (54) is provided
with an auxiliary oil reservoir (57) which is recessed in a radial
direction and is capable of accumulating oil together with the
crank chamber (54).
[0018] According to the third aspect of the present disclosure, the
oil which has been fed to the sliding surface of the crank shaft
(23) can be accumulated not only in the crank chamber (54), but
also in the auxiliary oil reservoir (57), This allows continuous
lubrication of the sliding portion between the crank shaft (23) and
the upper bearing (62) for a longer period of time even after the
oil shortage, compared to the case in which oil is accumulated in
only the crank chamber(54).
[0019] A fourth aspect of the present disclosure is an embodiment
of the third aspect of the present disclosure. In the fourth
aspect, the housing (50) is provided with an oil discharge passage
(56) whose upstream end is open to the inner wall surface of the
crank chamber (54) at a position away from a bottom surface of the
crank chamber (54) by a predetermined distance, and whose
downstream end is open to an outside of the housing (50), and the
auxiliary oil reservoir (57) is open to the inner wall surface of
the crank chamber (54) at a position lower in height than the oil
discharge passage (56).
[0020] According to the fourth aspect of the present disclosure,
the auxiliary oil reservoir (57) is open at a position lower in
height than the oil discharge passage (56). This prevents the oil
from being discharged from the crank chamber (54) and the auxiliary
oil reservoir (57) to the oil discharge passage (56) until the
level of the oil accumulated in the crank chamber (54) and the
auxiliary oil reservoir (57) reaches the opening position of the
upstream end of the oil discharge passage (56). It is therefore
possible to accumulate a predetermined amount of oil in the crank
chamber (54) and the auxiliary oil reservoir (57).
Advantages of the Invention
[0021] According to the aspects of the present disclosure, if oil
shortage occurs and oil feed to the upper bearing (62) through the
oil feed path (27) is stopped, the oil accumulated in the crank
chamber (54) is fed to the upper bearing (62) from the crank
chamber (54) through the bearing back-face passage (53a) and the
annular groove (24a) due to a pump effect of the spiral groove
(24b). This allows continuous lubrication of the sliding portion
between the crank shaft (23) and the upper bearing (62) even after
the oil shortage, as long as the oil is accumulated in the crank
chamber (54). As a result, seizing between the crank shaft (23) and
the upper bearing (62) may be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] [FIG. 1] FIG. 1 is a longitudinal cross-sectional view
illustrating a configuration of a scroll compressor according to a
first embodiment.
[0023] [FIG. 2] FIG. 2 is a longitudinal cross-sectional view
illustrating an oil flow in a normal operation.
[0024] [FIG. 3] FIG. 3 is a front view illustrating a shape of a
transfer groove formed in a crank shaft.
[0025] [FIG. 4] FIG. 4 corresponds to FIG. 2 and illustrates an oil
flow when oil in an oil reservoir is depleted.
[0026] [FIG. 5] FIG. 5 is a perspective view, part of which is a
cross-sectional view, illustrating a configuration of a housing of
a scroll compressor according to a second embodiment.
[0027] [FIG. 6] FIG. 6 is a perspective view illustrating the
configuration of the housing.
[0028] [FIG. 7] FIG. 7 is a horizontal cross-sectional view
illustrating the configuration of the housing.
[0029] [FIG. 8] FIG. 8 is a perspective cross-sectional view
illustrating an oil flow in a normal operation.
[0030] [FIG. 9] FIG. 9 corresponds to FIG. 8 and illustrates an oil
flow when oil in an oil reservoir is depleted.
DESCRIPTION OF EMBODIMENTS
[0031] Embodiments of the present invention will be described
below, based on the drawings. The following embodiments are merely
preferred examples in nature, and are not intended to limit the
scope, applications, and use of the invention.
First Embodiment
[0032] FIG. 1 is a longitudinal cross-sectional view illustrating a
configuration of a scroll compressor according to a first
embodiment of the present invention. A scroll compressor (10) is
connected, for example, to a refrigeration circuit which performs a
vapor compression refrigeration cycle in an air conditioner. The
scroll compressor (10) includes a casing (11), a rotary compression
mechanism (30), and a drive mechanism (20) which drives and rotates
the compression mechanism (30).
[0033] The casing (11) is comprised of a vertically-elongated
cylindrical d container with its both ends closed. The interior of
the casing (11) is divided into upper and lower spaces by a housing
(50) connected to an inner circumferential surface of the casing
(11). The space above the housing (50) constitutes an upper space
(15), and the space under the housing (50) constitutes a lower
space (16). The configuration of this housing (50) will be
described in detail later.
[0034] An oil reservoir (17) is provided at the bottom of the lower
space (16) of the casing (11). The oil reservoir (17) accumulates
oil for lubricating sliding portions of the scroll compressor
(10).
[0035] A suction pipe (18) and a discharge pipe (19) are attached
to the casing (11). One end of the suction pipe (18) is connected
to a suction pipe coupling (47). The discharge pipe (19) passes
through a body (12). One end of the discharge pipe (19) is open to
the lower space (16) of the casing (11).
[0036] The drive mechanism (20) includes a motor (21) and a crank
shaft (23). The motor (21) is housed in the lower space (16) of the
casing (11). The motor (21) has cylindrical stator (21a) and rotor
(21b). The stator (21a) is fixed to the inner circumferential
surface of the casing (11).
[0037] The rotor (21b) is arranged in a hollow of the stator (21a).
The crank shaft (23) is fixed to a hollow of the rotor (21b) so as
to pass through the rotor (21b), and the rotor (21b) and the crank
shaft (23) rotate integrally. The configuration of the crank shaft
(23) will be described in detail later.
[0038] The compression mechanism (30) is a so-called scroll
compression mechanism having a movable scroll (35), a fixed scroll
(40) and the housing (50). The housing (50) and the fixed scroll
(40) are coupled to each other with a bolt, with the movable scroll
(35) housed therebetween.
[0039] The movable scroll (35) has an approximately disc-shaped
movable end plate (36). A movable wrap (37) stands on the top
surface of the movable end plate (36). The movable wrap (37) is a
spiral-shaped wall extending radially outward from a portion near
the center of the movable end plate (36). Further, a boss (38)
projects from the lower surface of the movable end plate (36).
[0040] The fixed scroll (40) has an approximately disc-shaped fixed
end plate (41). A fixed wrap (42) stands on the lower surface of
the fixed end plate (41). The fixed wrap (42) is a spiral-shaped
wall extending radially outward from a portion near the center of
the fixed end plate (41), and is configured to engage with the
movable wrap (37) of the movable scroll (35). A compression chamber
(31) is formed between the fixed wrap (42) and the movable wrap
(37).
[0041] The fixed scroll (40) has an outer edge portion (43) which
is continuous to the fixed wrap (42) and extends radially outward
from the outermost wall of the fixed wrap (42). The lower end
surface of the outer edge portion (43) is fixed to the upper end
surface of the housing (50). Further, the outer edge portion (43)
has an opening (44) that is open upward. A suction port (34) which
connects the interior of the opening (44) and the outermost end of
the compression chamber (31) is formed in the outer edge portion
(43). The suction port (34) is open at a suction position of the
compression chamber (31). The suction pipe coupling (47) mentioned
above is connected to the opening (44) formed in the outer edge
portion (43).
[0042] A discharge port (32) is formed in the fixed end plate (41)
of the fixed scroll (40) at a position near the center of the fixed
wrap (42). The discharge port (32) vertically passes through the
fixed end plate (41). The lower end of the discharge port (32) is
open at a discharge position of the compression chamber (31). The
upper end of the discharge port (32) is open to a discharge chamber
(46) defined in an upper portion of the fixed scroll (40). Although
not shown, the discharge chamber (46) communicates with the lower
space (16) of the casing (11).
[0043] The housing (50) has an approximately cylindrical shape. The
outer peripheral surface of the housing (50) has a gradually
decreasing diameter from the top to the bottom of the housing (50).
An upper portion of this outer peripheral surface is fixed to the
inner circumferential surface of the casing (11).
[0044] The crank shaft (23) is inserted in a hollow of the housing
(50). Further, this hollow of the housing (50) has a larger
diameter at its upper portion, comparted to its lower portion,
since the housing (50) closer to its top surface is recessed. An
upper bearing portion (53) is provided at the lower portion of the
hollow. An upper bearing (62) is inserted in the upper bearing
portion (53). A bearing back-face passage (53a), which will be
described later, is formed in the housing (50) closer to the back
face of the upper bearing (62).
[0045] A sealing member (55) is fitted between the top surface of
the housing (50) and the back face of the movable scroll (35). The
upper hollow of the housing (50) is defined by the sealing member
(55) and constitutes a crank chamber (54).
[0046] The crank chamber (54) faces the back face of the movable
scroll (35). The boss (38) of the movable scroll (35) is located in
the crank chamber (54). A pin bearing (61) is inserted in the boss
(38).
[0047] A lower bearing portion (28) is fixed to the casing (11)
near the lower end of the body (12). A lower bearing (63) is
inserted in the lower bearing portion (28).
[0048] The crank shaft (23) includes a vertically-extending main
shaft portion (24) and an eccentric portion (25) provided at the
upper end of the main shaft portion (24). The main shaft portion
(24) and the eccentric portion (25) are integrally formed. The
eccentric portion (25) has a smaller diameter than the largest
diameter of the main shaft portion (24). The center of the
eccentric portion (25) is eccentric by a predetermined distance
with respect to the center of the main shaft portion (24). The
eccentric portion (25) engages with the pin bearing (61) of the
boss (38). The movable scroll (35) therefore revolves around when
the crank shaft (23) rotates.
[0049] An upper end portion of the main shaft portion (24) of the
crank shaft (23) is rotatably supported by the upper bearing (62)
of the upper bearing portion (53) of the housing (50). A lower end
portion of the main shaft portion (24) is rotatably supported by
the lower bearing (63) of the lower bearing portion (28).
[0050] An oil feed path (27) is formed in the crank shaft (23) so
as to extend along the axial direction of the crank shaft (23), The
oil feed path (27) branches to the pin bearing (61), the upper
bearing (62) and the lower bearing (63) from the axis along which
the oil feed path (27) extends.
[0051] An oil feed nozzle (26) is provided at a lower end portion
of the crank shaft (23) The oil feed nozzle (26) has a suction port
that is open to the oil reservoir (17) of the casing (11). The oil
feed nozzle (26) has a discharge port that is connected to the oil
feed path (27) formed in the crank shaft (23). Oil suctioned by the
oil feed nozzle (26) from the oil reservoir (17) of the casing (11)
is fed to the sliding portions, such as the pin bearing (61), the
upper bearing (62) and the lower bearing (63), of the scroll
compressor (10).
[0052] Oil fed from the oil feed path (27) to the sliding surface
between the pin bearing (61) and the eccentric portion (25) flows
down due to its own weight into the crank chamber (54). This means
that the crank chamber (54) has the same pressure as the lower
space (16) of the casing (11). This pressure of the crank chamber
(54) acts on the back face of the movable scroll (35), and pushes
the movable scroll (35) toward the fixed scroll (40).
[0053] The main shaft portion (24) of the crank shaft (23) has, on
its outer peripheral surface, an annular groove (24a) and a spiral
groove (24b). The annular groove (24a) is formed at a lower
position of the sliding surface with the upper bearing (62), and
extends in the circumferential direction of the main shaft portion
(24). The annular groove (24a) connects the crank chamber (54) and
the annular groove (24a).
[0054] Part of oil fed from the oil feed path (27) to the sliding
surface between the upper bearing (62) and the main shaft portion
(24) flows up into the crank chamber (54) The rest of the oil flows
down and is collected in the annular groove (24a).
[0055] The spiral groove (24b) is configured to transfer the oil
collected in the annular groove (24a) to the crank chamber (54).
Specifically, as illustrated in FIG. 3, the spiral groove (24b) is
tilted with respect to the axial direction of the crank shaft (23)
such that an upper end portion of the spiral groove (24b) is
located rearward of a lower end portion of the spiral groove (24b)
in a rotational direction (indicated by arrow in FIG. 3) of the
crank shaft (23). If the spiral groove (24b) is tilted in this
manner that is opposite to the rotational direction of the crank
shaft (23), the oil in the annular groove (24a) goes up along the
spiral groove (24b) due to viscosity pump effects, allowing the oil
to be transferred into the crank chamber (54).
[0056] The housing (50) is provided with the bearing back-face
passage (53a), which connects the crank chamber (54) and the
annular groove (24a), at a position closer to the back face of the
upper bearing (62). Specifically, the upper bearing (62) is
provided with a through hole (62a) which connects a lower end
portion of the bearing back-face passage (53a) and the annular
groove (24a). The bearing back-face passage (53a) communicates with
the annular groove (24a) via the through hole (62a). This
configuration allows the oil collected in the annular groove (24a)
to be transferred to the crank chamber (54) not only through the
spiral groove (24b) but also through the bearing back-face passage
(53a).
[0057] The housing (50) is provided with an oil discharge passage
(56) for discharging the oil which has flowed into the crank
chamber (54) to the outside of the housing (50). Specifically, the
upstream end of the oil discharge passage (56) is open to the inner
wall surface of the crank chamber (54) at a position away from the
bottom surface of the crank chamber (54) by a predetermined
distance. The downstream end of the oil discharge passage (56) is
open downward at a position closer to the outer periphery of the
housing (50) so as to communicate with the lower space (16).
[0058] This prevents the oil from being discharged from the crank
chamber (54) to the oil discharge passage (56) until the level of
the oil accumulated in the crank chamber (54) reaches the opening
position of the upstream end of the oil discharge passage (56). It
is thus possible to accumulate a predetermined amount of oil in the
crank chamber (54).
[0059] --Operation--
[0060] Operation of the above-described scroll compressor (10) will
now be described. As illustrated in FIG, 1, when the motor (21) of
the scroll compressor (10) is activated, the rotor (21b) and the
crank shaft (23) are rotated, and the movable scroll (35) revolves
around. This revolution of the movable scroll (35) periodically
increases and decreases the volume of the compression chamber
(31).
[0061] Specifically, when the crank shaft (23) rotates, a
refrigerant is sucked into the compression chamber (31) from the
suction port (34). As the crank shaft (23) continues to rotate, the
compression chamber (31) is completely closed. With further
rotation of the crank shaft (23), the volume of the compression
chamber (31) starts decreasing, and compression of the refrigerant
in the compression chamber (31) starts.
[0062] After that, the volume of the compression chamber (31)
further decreases, and the discharge port (32) opens when the
volume of the compression chamber (31) decreases to a predetermined
volume. Through this discharge port (32), the refrigerant
compressed in the compression chamber (31) is discharged to the
discharge chamber (46) of the fixed scroll (40). The refrigerant in
the discharge chamber (46) is discharged from the discharge pipe
(19) via the lower space (16) of the casing (11). As mentioned
above, the lower space (16) communicates with the crank chamber
(54). The movable scroll (35) is pushed toward the fixed scroll
(40) by the pressure of the refrigerant in the crank chamber
(54).
[0063] --Oil Feed in Normal Operation--
[0064] Oil teed in the scroll compressor (10) will now be
described. As illustrated in FIG. 2, when the compression mechanism
(30) starts operating, the oil in the oil reservoir (17) is sucked
up through the oil feed nozzle (26) due to centrifugal pump
effects. Then, the oil sucked up through the oil feed nozzle (26)
flows through the oil feed path (27) in the crank shaft (23) and is
fed to sliding portions, such as a thrust sliding surface between
the movable scroll (35) and the fixed scroll (40), a sliding
surface between the pin bearing (61) of the boss (38) and the
eccentric portion (25), a sliding surface between the upper bearing
(62) of the housing (50) and the main shaft portion (24), and a
sliding surface between the lower bearing (63) of the lower bearing
portion (28) and the main shaft portion (24). The oil which has
been fed to the respective sliding portions is collected in the oil
reservoir (17).
[0065] The oil which has been fed to the sliding surface between
the pin bearing (61) of the boss (38) and the eccentric portion
(25) flows in the crank chamber (54). Part of the oil which has
been fed to the sliding surface between the upper bearing (62) and
the main shaft portion (24) flows up into the crank chamber
(54).
[0066] The rest of the oil fed to the sliding surface between the
upper bearing (62) and the main shaft portion (24) flows down to be
collected in the annular groove (24a). The oil collected in the
annular groove (24a) passes through the spiral groove (24b) and the
bearing back-face passage (53a), and flows into the crank chamber
(54). The oil starts to be accumulated in the crank chamber (54).
When the oil level reaches the opening position of the oil
discharge passage (56), the oil in the crank chamber (54) passes
through the oil discharge passage (56) and is discharged to the
outside of the housing (50) to be collected in the oil reservoir
(17).
[0067] --Oil Feed in the Event of Oil Shortage--
[0068] Now oil feed in the scroll compressor (10) in the following
situation will be described in which an excessive oil discharge
occurs since a large amount of oil has been discharged to the
outside of the casing (11), and the oil accumulated in the oil
reservoir (17) is depleted, thus causing oil shortage.
[0069] As illustrated in FIG. 4, if oil shortage occurs and oil
feed to the upper bearing (62) through the oil feed path (27) is
stopped, the oil accumulated in the crank chamber (54) is fed from
the crank chamber (54) to the upper bearing (62) through the
bearing back-face passage (53a) and the annular groove (24a) due to
pump effects of the spiral groove (24b).
[0070] Thus, the oil circulates at the sliding portion between the
crank shaft (23) and the upper bearing (62) even after the oil
shortage, as long as the oil is accumulated in the crank chamber
(54). This allows continuous lubrication of the sliding portion,
and may reduce seizing between the crank shaft (3) and the upper
bearing (62).
Second Embodiment
[0071] In the following description, like reference characters are
used to designate the same elements as those in the first
embodiment, and only differences will be described.
[0072] As illustrated in FIGS. 5-7, the housing (50) includes the
crank chamber (54) which is a recessed portion of the housing (50)
closer to its top surface. The bottom of the crank chamber (54) is
provided with an annular elastic groove (29). The oil fed to the
sliding surface of the eccentric portion (25) through the oil feed
path (27) of the crank shaft (23) flows down, due to its own
weight, into the crank chamber (54).
[0073] The housing (50) is provided with the oil discharge passage
(56) for discharging the oil which has flowed into the crank
chamber (54) to the outside of the housing (50). Specifically, the
upstream end of the oil discharge passage (56) is open to the inner
wall surface of the crank chamber (54) at a position away from the
bottom surface of the crank chamber (54) by a predetermined
distance. The downstream end of the oil discharge passage (is open
downward at a position closer to the outer periphery of the housing
(50) so as to communicate the lower space (16).
[0074] The inner wall surface of the crank chamber (54) is provided
with auxiliary oil reservoirs (57) recessed in a radial direction.
Specifically, the auxiliary oil reservoirs (57) are comprised of
holes each passing through the housing (50) in the radial direction
from the inner wall surface of the crank chamber (54), and this
housing (50) is fitted and fixed to the body (12) of the casing
(11) to allow the hole to accumulate oil.
[0075] The auxiliary oil reservoirs (57) are for accumulating part
of the oil which has flowed into the crank chamber (54), and
arranged at six positions of the housing (50) which are spaced
apart from each other in the circumferential direction of the
housing (50) (see FIG. 7).
[0076] Thus, oil can be accumulated no only in the crank chamber
(54), hut also in the auxiliary oil reservoirs (57). This allows
continuous lubrication of the sliding portion between the crank
shaft (23) and the upper bearing (62) for a longer period of time
even after the oil shortage, compared to the case in which oil is
accumulated in only the crank chamber (54).
[0077] Further, the auxiliary oil reservoirs (57) are open to the
inner wall surface of the crank chamber (54) at positions lower in
height than the oil discharge passage (56). This prevents the oil
from being discharged from the crank chamber (54) and the auxiliary
oil reservoirs (57) to the oil discharge passage (56) until the
level of the oil accumulated in the crank chamber (54) and the
auxiliary oil reservoirs (57) reaches the opening position of the
upstream end of the oil discharge passage (56). It is thus possible
to accumulate a predetermined amount of oil in the crank chamber
(54) and the auxiliary oil reservoirs (57).
[0078] Note that the number and positions of the auxiliary oil
reservoirs (57) are merely examples, and are not limited
thereto.
[0079] --Oil Feed in Normal Operation--
[0080] Oil feed in normal operation will now be described. As
illustrated in FIG. 8, the oil which has flowed through the oil
feed path (7) of the crank shaft (23) and has been fed to the
sliding surface of the eccentric portion (25) flows into the crank
chamber (54) and the auxiliary oil reservoirs (57). Further, part
of the oil which has been fed to the sliding surface between the
upper bearing (62) and the main shaft portion (24) flows up into
the crank chamber (54) and the auxiliary oil reservoirs (57).
[0081] The rest of the oil fed to the sliding surface between the
upper bearing (62) and the main shaft portion (24) flows down to be
collected in the annular groove (24a). The oil collected in the
annular groove (24a) passes through the spiral groove (24b) and the
beating back-face passage (53a), and flows into the crank chamber
(54) and the auxiliary oil reservoirs (57). The oil starts to be
accumulated in the crank chamber (54) and the auxiliary oil
reservoirs (57). When the oil level reaches the opening position of
the oil discharge passage (56), the oil in the crank chamber (54)
and the auxiliary oil reservoirs (57) passes through the oil
discharge passage (56) and is discharged to the outside of the
housing (50) (see FIG. 5).
[0082] --Oil Feed in the Event of Oil Shortage--
[0083] Oil feed in the event of oil shortage will now be described.
As illustrated in FIG. 9, if oil shortage occurs and oil feed to
the upper bearing (62) through the oil feed path (27) is stopped,
the oil accumulated in the crank chamber (54) and the auxiliary oil
reservoirs (57) is fed to the upper bearing (62) through the
bearing back-face passage (53a) and the annular groove (24a) from
the crank chamber (54) and the auxiliary oil reservoirs (57) due to
pump effects of the spiral groove (24b).
[0084] Thus, the oil circulates at the sliding portion between the
crank shaft (23) and the upper bearing (62) even after the oil
shortage, as long as the oil is accumulated in the crank chamber
(54) and the auxiliary oil reservoirs (57). This allows continuous
lubrication of the sliding portion, and may reduce seizing between
the crank shaft (23) and the upper bearing (62).
INDUSTRIAL APPLICABILITY
[0085] As can been seen from the foregoing description, the present
invention produces practical effects, that is, allowing continuous
lubrication of a sliding portion between a crank shaft and a
bearing even in a situation in which no oil is fed to a sliding
surface of the crank shaft through an oil feed path during rotation
of the crank shaft. The present invention is therefore very useful
with high industrial applicability.
DESCRIPTION OF REFERENCE CHARACTERS
[0086] 10 scroll compressor
[0087] 11 casing
[0088] 17 oil reservoir
[0089] 23 crank shaft
[0090] 24a annular groove
[0091] 24b transfer groove
[0092] 27 oil feed path
[0093] 35 movable scroll
[0094] 38 boss
[0095] 40 fixed scroll
[0096] 50 housing
[0097] 53a bearing back-face passage
[0098] 54 crank chamber
[0099] 57 auxiliary oil reservoir
[0100] 62 upper bearing
* * * * *