U.S. patent application number 13/497620 was filed with the patent office on 2012-10-25 for hermetic compressor.
This patent application is currently assigned to PANASONIC CORPORATION. Invention is credited to Noboru Iida, Osamu Ogawa, Atsuo Okaichi, Shingo Oyagi, Fuminori Sakima.
Application Number | 20120269667 13/497620 |
Document ID | / |
Family ID | 45723103 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120269667 |
Kind Code |
A1 |
Sakima; Fuminori ; et
al. |
October 25, 2012 |
HERMETIC COMPRESSOR
Abstract
A hermetic compressor (100) includes a closed casing (2), a
compression mechanism (4), a motor (6), a discharge pipe (8), a
first balance weight (18), a swirl flow generating portion (21),
and a second balance weight (19). The motor (6) has a stator (14)
and a rotor (15). A communication passage (20) is formed in the
rotor (15) so as to introduce, into an upper space (7), a working
fluid compressed in the compression mechanism (4) and discharged to
a lower space (5) of the closed casing (2). A baffle plate (122) is
provided as a discharge direction deflecting portion for causing
the compressed working fluid to travel from the communication
passage (20) to the upper space (7), while deflecting the working
fluid in a direction inclined with respect to a direction parallel
to a rotational axis O. The baffle plate (122) may be constituted
by a part of the swirl flow generating portion (21).
Inventors: |
Sakima; Fuminori; (Osaka,
JP) ; Ogawa; Osamu; (Kyoto, JP) ; Okaichi;
Atsuo; (Osaka, JP) ; Iida; Noboru; (Shiga,
JP) ; Oyagi; Shingo; (Kyoto, JP) |
Assignee: |
PANASONIC CORPORATION
Kadoma-shi, Osaka
JP
|
Family ID: |
45723103 |
Appl. No.: |
13/497620 |
Filed: |
August 10, 2011 |
PCT Filed: |
August 10, 2011 |
PCT NO: |
PCT/JP2011/004543 |
371 Date: |
March 22, 2012 |
Current U.S.
Class: |
417/423.7 |
Current CPC
Class: |
F04C 2240/807 20130101;
F04C 23/02 20130101; F04C 29/026 20130101; F04C 23/008 20130101;
F04C 29/12 20130101; F04B 39/04 20130101; F04C 29/045 20130101;
F04C 29/0021 20130101; F04C 18/356 20130101 |
Class at
Publication: |
417/423.7 |
International
Class: |
F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2010 |
JP |
2010-185878 |
Claims
1. A hermetic compressor comprising: a closed casing having an oil
reservoir in its bottom portion; a compression mechanism, disposed
in the closed casing, for compressing a working fluid; a motor,
disposed above the compression mechanism in the closed casing, for
driving the compression mechanism, the motor having a rotor and a
stator; an upper space, formed above the motor, as a part of an
internal space of the closed casing; a lower space, formed between
the motor and the compression mechanism, as a part of the internal
space of the closed casing; a discharge pipe opening into the upper
space, for discharging the compressed working fluid outside the
hermetic compressor; a first balance weight protruding from an
upper surface of the rotor toward the upper space; a swirl flow
generating portion protruding from the upper surface of the rotor
toward the upper space, the swirl flow generating portion being
disposed at a position closer to a rotational axis of the motor
than the first balance weight; a second balance weight protruding
from a lower surface of the rotor toward the lower space; and a
communication passage formed in the rotor so as to introduce, into
the upper space, the working fluid compressed in the compression
mechanism and discharged to the lower space, wherein when a
three-dimensional annular trajectory of the first balance weight
formed around the rotational axis when the motor is driven is
defined as a first trajectory, a plane obtained by cutting the
first trajectory with a first plane parallel to the rotational axis
and including the rotational axis is defined as a first cross
section, a three-dimensional annular trajectory of the second
balance weight formed around the rotational axis when the motor is
driven is defined as a second trajectory, a plane obtained by
cutting the second trajectory with a second plane parallel to the
rotational axis and including the rotational axis is defined as a
second cross section, a three-dimensional annular trajectory of the
swirl flow generating portion formed around the rotational axis
when the motor is driven is defined as a third trajectory, a plane
obtained by cutting the third trajectory with a third plane
parallel to the rotational axis and including the rotational axis
is defined as a third cross section, an area of a micro-region
included in a specific region on an arbitrary plane parallel to the
rotational axis and including the rotational axis is defined as dA,
a distance from the rotational axis to a centroid of the
micro-region is defined as r, and a value M.sub.A represented by
the following equation (1) is defined as a second moment of area, [
Equation 1 ] M A = .intg. A r 2 A ( 1 ) ##EQU00002## a sum of a
second moment of area of the first cross section and a second
moment of area of the third cross section is greater than a second
moment of area of the second cross section, and the hermetic
compressor further comprises a discharge direction deflecting
portion for causing the compressed working fluid to travel from the
communication passage to the upper space, while deflecting the
working fluid in a direction inclined with respect to a direction
parallel to the rotational axis.
2. The hermetic compressor according to claim 1, wherein the swirl
flow generating portion is also used as the discharge direction
deflecting portion.
3. The hermetic compressor according to claim 1, wherein the
discharge direction deflecting portion is configured to direct the
compressed working fluid in a direction opposite to a rotational
direction of the rotor.
4. The hermetic compressor according to claim 2, wherein the swirl
flow generating portion includes, as the discharge direction
deflecting portion, a baffle plate protruding from the upper
surface of the rotor toward the upper space, and an image obtained
by projecting the baffle plate onto the upper surface of the rotor
overlaps an outlet of the communication passage.
5. The hermetic compressor according to claim 1, wherein an outlet
part of the communication passage extends in the direction inclined
with respect to the direction parallel to the rotational axis so
that the compressed working fluid travels from the communication
passage to the upper space, while being deflected in a direction
that is opposite to a rotational direction of the rotor and is
inclined with respect to the direction parallel to the rotational
axis, and the discharge direction deflecting portion is constituted
by the outlet part.
6. The hermetic compressor according to claim 5, wherein the swirl
flow generating portion includes a baffle plate protruding
obliquely from the upper surface of the rotor so as to extend in
the same direction as the outlet part, and an image obtained by
projecting the baffle plate onto the upper surface of the rotor
overlaps an outlet of the communication passage.
7. The hermetic compressor according to claim 1, further comprising
a swirl flow suppressing portion for reducing an area of a
displacement surface of the second balance weight, the displacement
surface displacing the working fluid.
8. The hermetic compressor according to claim 7, wherein the swirl
flow suppressing portion is constituted by a cover that covers the
second balance weight so that the area of the displacement surface
of the second balance weight is zero, the displacement surface
displacing the working fluid.
9. The hermetic compressor according to claim 8, wherein the cover
is formed integrally with an end plate for clamping and fixing
constituent elements of the rotor.
10. The hermetic compressor according to claim 7, wherein the swirl
flow suppressing portion is provided along a rotational trajectory
of the second balance weight, and the swirl flow suppressing
portion has a smaller specific gravity than the second balance
weight.
11. The hermetic compressor according to claim 10, wherein the
swirl flow suppressing portion is made of a material having voids
into which the working fluid containing oil particles can
penetrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hermetic compressor, and
more specifically to a technique for separating lubricating oil
from a compressed working fluid.
BACKGROUND ART
[0002] A known conventional example of an oil separation mechanism
usable in a hermetic compressor is Patent Literature 1. FIG. 25
shows an overview of a compressor described in Patent Literature 1.
A motor including a rotor 211 and a stator 213 is disposed in a
closed casing 203 of the compressor. A compression mechanism (not
shown) is disposed below the motor. A refrigerant compressed in the
compression mechanism is discharged into the internal space of the
closed casing 203. An oil separation plate 237 that rotates
together with the rotor 211 is provided at the end of the rotor
211. The oil separation plate 237 applies a centrifugal force to a
multiphase flow of the compressed refrigerant and oil.
[0003] As shown in FIG. 26A and FIG. 26B, the oil separation plate
237 has an approximately disk shape. Projections 239 and recesses
245 are formed radially on the bottom surface of the oil separation
plate 237. The projections 239 and the recesses 245 each extend
continuously to the outer periphery of the oil separation plate
237. The flow of the refrigerant containing oil particles travels
along the projections 239, is scattered by the centrifugal force
from the end of each projection 239, and collides with the inner
peripheral surface of the rotor 213. Thus, the oil is separated
from the refrigerant. The refrigerant is discharged outside the
closed casing 203 through a discharge pipe 235.
[0004] Patent Literature 2 discloses a method of causing a
compressed refrigerant to pass through an insulator so as to
promote the separation of oil from the refrigerant.
[0005] In the compressor described in Patent Literature 1 or 2, the
separated oil returns to an oil reservoir in the bottom portion of
the closed casing through a gap between the rotor and the stator or
through a gap between the stator and the closed casing.
CITATION LIST
Patent Literature
[0006] Patent Literature 1 JP 11(1999)-107967 A [0007] Patent
Literature 2 JP 2009-144581 A
SUMMARY OF INVENTION
Technical Problem
[0008] With the techniques disclosed in Patent Literatures 1 and 2,
the oil can be efficiently separated from the refrigerant. However,
no particular consideration is given to the return of the separated
oil to the oil reservoir. For example, when a strong swirl flow is
generated in a space below the motor, the oil separated in a space
above the motor is hard to return to the oil reservoir. As a
result, the oil, once separated from the refrigerant, is again
mixed therewith, and discharged outside the compressor through the
discharge pipe.
[0009] It is an object of the present invention to provide a
hermetic compressor with less discharge of oil.
Solution to Problem
[0010] The present invention provides a hermetic compressor
including: a closed casing having an oil reservoir in its bottom
portion; a compression mechanism, disposed in the closed casing,
for compressing a working fluid; a motor, disposed above the
compression mechanism in the closed casing, for driving the
compression mechanism, the motor having a rotor and a stator; an
upper space, formed above the motor, as a part of an internal space
of the closed casing; a lower space, formed between the motor and
the compression mechanism, as a part of the internal space of the
closed casing; a discharge pipe opening into the upper space, for
discharging the compressed working fluid outside the hermetic
compressor; a first balance weight protruding from an upper surface
of the rotor toward the upper space; a swirl flow generating
portion protruding from the upper surface of the rotor toward the
upper space, the swirl flow generating portion being disposed at a
position closer to a rotational axis of the motor than the first
balance weight; a second balance weight protruding from a lower
surface of the rotor toward the lower space; and a communication
passage formed in the rotor so as to introduce, into the upper
space, the working fluid compressed in the compression mechanism
and discharged to the lower space. When a three-dimensional annular
trajectory of the first balance weight formed around the rotational
axis when the motor is driven is defined as a first trajectory, a
plane obtained by cutting the first trajectory with a first plane
parallel to the rotational axis and including the rotational axis
is defined as a first cross section, a three-dimensional annular
trajectory of the second balance weight formed around the
rotational axis when the motor is driven is defined as a second
trajectory, a plane obtained by cutting the second trajectory with
a second plane parallel to the rotational axis and including the
rotational axis is defined as a second cross section, a
three-dimensional annular trajectory of the swirl flow generating
portion formed around the rotational axis when the motor is driven
is defined as a third trajectory, a plane obtained by cutting the
third trajectory with a third plane parallel to the rotational axis
and including the rotational axis is defined as a third cross
section, an area of a micro-region included in a specific region on
an arbitrary plane parallel to the rotational axis and including
the rotational axis is defined as dA, a distance from the
rotational axis to a centroid of the micro-region is defined as r,
and a value M.sub.A represented by the following equation (1) is
defined as a second moment of area,
[ Equation 1 ] M A = .intg. A r 2 A ( 1 ) ##EQU00001##
[0011] a sum of a second moment of area of the first cross section
and a second moment of area of the third cross section is greater
than a second moment of area of the second cross section. The
hermetic compressor further includes a discharge direction
deflecting portion for causing the compressed working fluid to
travel from the communication passage to the upper space, while
deflecting the working fluid in a direction inclined with respect
to a direction parallel to the rotational axis.
Advantageous Effects of Invention
[0012] According to the present invention, the sum of the second
moment of area of the first cross section and the second moment of
area of the third cross section is greater than the second moment
of area of the second cross section. That is, the swirl flow in the
upper space is stronger and the swirl flow in the lower space is
weaker. This promotes the effect of separating the oil from the
working fluid by a centrifugal force in the upper space.
Furthermore, the return of the oil from the upper space to the oil
reservoir can be facilitated by increasing the swirl flow in the
upper space and reducing the swirl flow in the lower space
relatively. This can prevent lubrication failure from occurring in
the compression mechanism due to a drop in the oil level. Moreover,
since the stability of the oil level is enhanced by reducing the
swirl flow in the lower space, splashing of the oil can also be
reduced.
[0013] Furthermore, since the discharge direction deflecting
portion is provided, the compressed working fluid travels from the
communication passages to the upper space, while being deflected in
a direction inclined with respect to a direction parallel to the
rotational axis. This allows the swirl flow of the working fluid to
be generated at a position closer to the outlet of the
communication passage in the direction parallel to the rotational
axis of the motor. As a result, the flow distance of the working
fluid in the upper space can be increased, which can reduce the
discharge of the oil from the compressor.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a cross-sectional view of a compressor according
to an embodiment of the present invention.
[0015] FIG. 2 is a perspective view of a rotor and balance
weights.
[0016] FIG. 3 is a perspective view of the rotor on which the
balance weights and a swirl flow generating portion are
provided.
[0017] FIG. 4 is a perspective view of the rotor on which another
swirl flow generating portion is provided.
[0018] FIG. 5 is a perspective view of a swirl flow suppressing
portion.
[0019] FIG. 6A is a perspective view showing the definitions of a
first cross section and a second cross section.
[0020] FIG. 6B is a plan view showing the definitions of the first
cross section and the second cross section.
[0021] FIG. 7A is a perspective view showing the definition of a
third cross section.
[0022] FIG. 7B is a plan view showing the definition of the third
cross section.
[0023] FIG. 8 is a schematic diagram showing the definition of a
second moment of area.
[0024] FIG. 9 is a schematic diagram showing the flow of
refrigerant and the flow of oil in the compressor.
[0025] FIG. 10 is a schematic diagram showing a pressure field of a
model in which a rotor is placed in a cylindrical container.
[0026] FIG. 11 is a schematic diagram showing the flow of
refrigerant and the flow of oil in a compressor without a swirl
flow generating portion.
[0027] FIG. 12 is a schematic diagram showing a pressure difference
between two openings of a flow path.
[0028] FIG. 13A is a perspective view of a rotor without a swirl
flow generating portion.
[0029] FIG. 13B is a schematic diagram showing a refrigerant flow
in the vicinity of an outlet of a communication passage formed in
the rotor shown in FIG. 13A.
[0030] FIG. 14A is a perspective view of a rotor with a swirl flow
generating portion incapable of deflecting a refrigerant flow.
[0031] FIG. 14B is a schematic diagram showing a refrigerant flow
in the vicinity of an outlet of a communication passage formed in
the rotor shown in FIG. 14A.
[0032] FIG. 15A is a perspective view of the rotor of the present
embodiment.
[0033] FIG. 15B is a schematic diagram showing a refrigerant flow
in the vicinity of an outlet of a communication passage formed in
the rotor of FIG. 15A.
[0034] FIG. 16 is a schematic diagram showing a flow field in the
upper space of the rotary compressor of the present embodiment.
[0035] FIG. 17 is a schematic diagram showing a flow field in the
upper space of a rotary compressor provided with the swirl flow
generating portion shown in FIG. 14A.
[0036] FIG. 18 is a graph showing the results of experiments
conducted to ascertain the effect of the rotary compressor of the
present embodiment.
[0037] FIG. 19 is a cross-sectional view of a compressor according
to a first modification.
[0038] FIG. 20 is a perspective view of a swirl flow suppressing
portion according to a second modification.
[0039] FIG. 21 is a cross-sectional view showing a preferred
position of a discharge port.
[0040] FIG. 22 is a perspective view of a swirl flow suppressing
portion according to a third modification.
[0041] FIG. 23 is a perspective view of a swirl flow generating
portion according to a fourth modification.
[0042] FIG. 24A is a schematic cross-sectional view of a discharge
direction deflecting portion according to a fifth modification.
[0043] FIG. 24B is a schematic cross-sectional view of a swirl flow
generating portion and a discharge direction deflecting portion
according to a sixth modification.
[0044] FIG. 25 is a cross-sectional view of a conventional hermetic
compressor.
[0045] FIG. 26A is a bottom view of an oil separation plate
provided in the conventional hermetic compressor.
[0046] FIG. 26B is a cross-sectional view of the oil separation
plate shown in FIG. 26A, taken along the line B-B.
DESCRIPTION OF EMBODIMENTS
[0047] Hereinafter, the embodiments of the present invention will
be described with reference to the drawings.
[0048] As shown in FIG. 1, a rotary compressor 100 of the present
embodiment includes a closed casing 2, a compression mechanism 4,
and a motor 6. The compression mechanism 4 and the motor 6 are
disposed in one closed casing 2. That is, the rotary compressor 100
is configured as a hermetic compressor. In the closed casing 2, the
motor 6 is located above the compression mechanism 4. The closed
casing 2 has an oil reservoir 3 formed in its bottom portion. The
compression mechanism 4 is immersed in oil (refrigerating machine
oil) held in the oil reservoir 3. The compression mechanism 4 is
coupled to the motor 6 by a shaft 9 so as to be driven by the motor
6. A lower space 5 and an upper space 7 are formed in the closed
casing 2. The lower space 5 is a space formed between the
compression mechanism 4 and the motor 6 in the axial direction of
the shaft 9. The upper space 7 is a space formed above the motor 6.
The longitudinal direction of the shaft 9 is parallel to the
vertical direction. That is, the rotary compressor 100 is a
vertical rotary compressor.
[0049] The compression mechanism 4 has an upper bearing 12, a
piston 10, a cylinder 11, and a lower bearing 13. The piston 10 is
fitted to an eccentric portion 9a of the shaft 9 within the
cylinder 11. A compression chamber 11c having a crescent shape in
plan view is formed between the outer peripheral surface of the
piston 10 and the inner peripheral surface of the cylinder 11. A
torque generated in the motor 6 is transmitted to the piston 10 by
the shaft 9. As the piston 10 rotates within the cylinder 11, a
refrigerant is compressed in the compression chamber 11c. The type
of the refrigerant as a working fluid is not particularly limited.
A fluorine-containing refrigerant such as R410A or a natural
refrigerant such as carbon dioxide can be used.
[0050] The upper bearing 12 and the lower bearing 13 are mounted on
the top and the bottom of the cylinder 11, respectively. The shaft
9 is rotatably supported by the upper bearing 12 and the lower
bearing 13. A discharge muffler 24 having a discharge port 25 is
provided on the top of the upper bearing 12. The compressed
refrigerant travels from the compression mechanism 4 to the lower
space 5 through the interior of the discharge muffler 24 and the
discharge port 25. An oil passage 26 for returning the oil
separated from the refrigerant in the lower space 5 or the upper
space 7 to the oil reservoir 3 is formed along the outer periphery
of the upper bearing 12.
[0051] A discharge pipe 8 for discharging the compressed
refrigerant outside the closed casing 2 is provided in the top
portion of the closed casing 2. A suction pipe 23 for introducing
the refrigerant to be compressed into the compression mechanism 4
is provided in the side portion of the closed casing 2. The
discharge pipe 8 penetrates the top portion of the closed casing 2
and opens into the upper space 7. The suction pipe 23 penetrates
the side portion of the closed casing 2 and is inserted into the
cylinder 11.
[0052] The motor 6 includes a stator 14 and a rotor 15. The stator
14 is fixed to the inner wall of the closed casing 2. The stator 14
has an annular shape when viewed in the axial direction, and the
rotor 15 is disposed within the stator 14. The rotor 15 is fixed to
the shaft 9. Therefore, the rotational axis of the motor 6
coincides with the rotational axis O of the shaft 9. A small gap 16
(air gap) is formed between the inner peripheral surface of the
stator 14 and the outer peripheral surface of the rotor 15 in the
radial direction. A plurality of slit-shaped flow paths 17
extending in a direction parallel to the rotational axis O are
formed between the outer peripheral surface of the stator 14 and
the inner peripheral surface of the closed casing 2.
[0053] The rotor 15 has a plurality of communication passages 20
communicating the lower space 5 and the upper space 7. The
communication passages 20 are formed at equal angular intervals
around the rotational axis O of the shaft 9, and each of them
penetrates the rotor 15 in the direction parallel to the axial
direction of the shaft 9. The refrigerant compressed in the
compression mechanism 4 travels from the lower space 5 to the upper
space 7 through the gap 16, the flow paths 17, or the communication
passages 20. The oil separated from the refrigerant in the upper
space 7 returns from the upper space 7 to the lower space 5 through
the gap 16, the flow paths 17, or the communication passages 20. In
the present embodiment, the rotor 15 has four communication
passages 20, but the number of the communication passages 20 is not
particularly limited.
[0054] As shown in FIG. 2, the rotor 15 has, as constituent
elements of the rotor 15, a stack of steel plates 28, end plates 27
disposed on the top and the bottom of the stack of steel plates 28
to clamp the steel plates 28 therebetween and fix them together,
and rivets (not shown). In order to prevent whirling of the rotor
15 during its rotation, a first balance weight 18 and a second
balance weight 19 are provided on the top and the bottom of the
rotor 15, respectively. The balance weights 18 and 19 each have an
arcuate shape, and surround the communication passages 20 in plan
view. The second balance weight 19 is disposed symmetrically to the
first balance weight 18 with respect to the rotational axis O of
the shaft 9. That is, the second balance weight 19 is disposed at a
position 180 degrees opposite to the position of the first balance
weight 18 with respect to the rotational direction of the shaft
9.
[0055] The second balance weight 19 is heavier than the first
balance weight. The second balance weight 19 is located closer to
the supporting point of the shaft 9 (the upper bearing 12 and the
lower bearing 13) than the first balance weight 18. Therefore, the
effect of preventing the whirling motion can be enhanced by making
the second balance weight 19 relatively heavy.
[0056] As shown in FIG. 1 and FIG. 3, a swirl flow generating
portion 21 is provided on the top of the rotor 15 to increase a
swirl flow in the upper space 7. The swirl flow generating portion
21 protrudes from the upper surface of the rotor 15 toward the
upper space 7 and is disposed at a position closer to the
rotational axis O than the first balance weight 18. Specifically,
the swirl flow generating portion 21 includes a supporting ring 121
and baffle plates 122. The supporting ring 121 is a plate-like
member, and is located closer to the rotational axis O than the
communication passages 20 on the upper surface of the rotor 15. The
baffle plates 122 have a flat plate shape and are formed integrally
with the supporting ring 121 on the outer periphery of the
supporting ring 121. Four baffle plates 122 are provided at equal
angular intervals along the circumferential direction of the
supporting ring 121. Each of the baffle plates 122 protrudes
obliquely from the upper surface of the rotor 15 toward the upper
space 7 (i.e., in a direction inclined with respect to a direction
parallel to the rotational axis O of the motor 6). In the present
embodiment, the swirl flow generating portion 21 has the same
number of baffle plates 122 as the communication passages 20. The
protruding direction of each baffle plate 122 is set to, for
example, 30 to 60 degrees, and typically 45 degrees, with respect
to the direction perpendicular to the rotational axis O (i.e., a
horizontal direction (=0 degrees).
[0057] The baffle plate 122 is provided at the outlet of the
communication passage 20. Specifically, the baffle plate 122 is
located in the rotational direction of the rotor 15 from the outlet
of the communication passage 20. An image obtained by projecting
the baffle plate 122 onto the upper surface of the rotor 15
overlaps the outlet of the communication passage 20. That is, the
communication passage 20 is partially or entirely covered by the
baffle plate 122. By the function of the baffle plate 122, the
compressed refrigerant travels from the communication passage 20 to
the upper space 7, while being deflected in the direction inclined
with respect to the direction parallel to the rotational axis O. As
described above, the baffle plate 122 serves as a discharge
direction deflecting portion for deflecting the discharge direction
of the refrigerant. In the present embodiment, in order to suppress
an increase in the number of components, the swirl flow generating
portion 21 is also used as a discharge direction deflecting portion
(baffle plate 122).
[0058] In the present embodiment, the baffle plates 122 each are
configured to direct the compressed refrigerant in a rotational
direction opposite to that of the rotor 15 (hereinafter referred to
as a "opposite rotational direction"). This configuration can
prevent the refrigerant in the upper space 7 and the refrigerant
discharged from the communication passages 20 from colliding with
each other at right angles. Therefore, the refrigerant discharged
from the communication passages 20 can travel smoothly to the upper
space 7. This means that the pressure loss at the outlet of the
communication passage 20 is less likely to increase.
[0059] The swirl flow generating portion 21 may have the baffle
plate 122 at a position where it does not cover the outlet of the
communication passage 20. The baffle plate 122 provided at such a
position also has a function of increasing the swirl flow in the
upper space 7, but does not have a function of deflecting the
discharge direction of the refrigerant. Therefore, the flow
distance of the refrigerant in the upper space 7 cannot be
increased.
[0060] In order to further reduce the number of components, the
baffle plate 122 may be formed as a part of the end plate 27.
Specifically, as shown in FIG. 4, the baffle plate 122 can be
formed by cutting and raising a part of the end plate 27 at a
position covering the communication passage 20. In a configuration
shown in FIG. 4, the baffle plate 122 thus cut and raised serves as
a swirl flow generating portion and a discharge direction
deflecting portion. The shape of the discharge direction deflecting
portion is not limited to a plate shape as long as it has a
function of deflecting the discharge direction of the
refrigerant.
[0061] As shown in FIG. 1 and FIG. 5, a swirl flow suppressing
portion 22 is provided beneath the rotor 15 to reduce the swirl
flow in the lower space 5. Specifically, the swirl flow suppressing
portion 22 is constituted by an annular cover 22 that completely
covers the second balance weight 19. When the second balance weight
19 is covered by the cover 22 to suppress the swirl flow in the
lower space 5, the pressure at the opening of the flow path 17 on
the lower space 5 side drops. Thereby, the oil separated in the
upper space 7 can be returned smoothly to the lower space 5 and the
oil reservoir 3 through the flow path 17. Furthermore, since the
stability of the oil level is enhanced by suppressing the swirl
flow in the lower space 5, splashing of oil in the oil reservoir 3
can be reduced.
[0062] In the present embodiment, the first balance weight 18, the
second balance weight 19, the swirl flow generating portion 21 and
the swirl flow suppressing portion 22 are designed to increase the
swirl flow in the upper space 7 and reduce the swirl flow in the
lower space 5. One of the factors in the generation of swirl flows
in the lower space 5 and the upper space 7 is that the refrigerant
filled in the lower space 5 and the upper space 7 is subjected to
the displacement action of the first balance weight 18, the second
balance weight 19, and the swirl flow generating portion 21.
[0063] As shown in FIG. 6A and FIG. 6B, a three-dimensional annular
trajectory of the first balance weight 18 formed around the
rotational axis O when the motor 6 is driven is defined as a first
trajectory, and a plane obtained by cutting the first trajectory
with a first plane parallel to the rotational axis O and including
the rotational axis O is defined as a first cross section 33.
[0064] The first cross section 33 can also be defined as follows. A
plane that is a part of the surface of the first balance weight 18
and applies displacement action to the refrigerant when the motor 6
is driven is defined as a first displacement surface 18p, and an
image obtained by projecting the first displacement surface 18p
onto the first plane parallel to the rotational axis O and
including the rotational axis O is defined as a first projected
image. The first projected image can have various shapes and areas
because the first plane can be determined without limitation, but
herein the first plane is determined so that the area of the first
projected image has a maximum value. In this case, the first
projected image coincides with the first cross section 33.
[0065] For the second balance weight 19, a second cross section 34,
a second displacement surface 19p, a second plane, and a second
projected image can be defined according to the same criteria as
applied to the first balance weight 18.
[0066] Furthermore, for the swirl flow generating portion 21, a
third cross section 35, a third displacement surface, a third
plane, and a third projected image can be defined according to the
same criteria as applied to the first balance weight 18.
Specifically, as shown in FIG. 7A and FIG. 7B, a three-dimensional
annular trajectory of the swirl flow generating portion 21 formed
around the rotational axis O when the motor 6 is driven is defined
as a third trajectory, and a plane obtained by cutting the third
trajectory with a third plane parallel to the rotational axis O and
including the rotational axis O is defined as a third cross section
35. In the present embodiment, four baffle plates 122 for applying
displacement action to the refrigerant are provided. Therefore, the
third cross section 35 is composed of four cross sections having
the same shape.
[0067] The third cross section 35 also can be defined as follows. A
plane that is a part of the surface of the swirl flow generating
portion 21 and applies displacement action to the refrigerant when
the motor 6 is driven is defined as a third displacement surface
21p, and an image obtained by projecting the third displacement
surface 21p onto the third plane parallel to the rotational axis O
and including the rotational axis O is defined as a third projected
image. In the present embodiment, the surface of the baffle plate
122 forms the third displacement surface 21p. The third projected
image can have various shapes and areas because the third plane can
be determined without limitation, but herein the third plane is
determined so that the area of the third projected image has a
maximum value. In this case, the third projected image coincides
with the third cross section 35.
[0068] Next, as shown in FIG. 8, the area of a micro-region 136
included in a specific region 135 on an arbitrary plane parallel to
the rotational axis O and including the rotational axis O is
defined as dA, the distance from the rotational axis O to the
centroid of the micro-region 136 is defined as r, the length of the
micro-region 136 in a radial direction is defined as dr, the height
of the micro-region 136 in a direction parallel to the rotational
axis O is defined as dh, and the value M.sub.A represented by the
following equation (1) is defined as a second moment of area. In
FIG. 8, the micro-region 136 is rectangular.
[Equation 2]
M.sub.A=.intg.r.sup.2dA=.intg..intg.r.sup.2dhdr (1)
[0069] Furthermore, the second moment of area of the first cross
section 33 is defined as a 1st second moment of area M.sub.A1.
Likewise, the second moment of area of the second cross section 34
is defined as a 2nd second moment of area M.sub.A2. Likewise, the
second moment of area of the third cross section 35 is defined as a
3rd second moment of area M.sub.A3. The 1st to 3rd second moments
of area can be calculated using Equation (1) for the first cross
section 33, the second cross section 34, and the third cross
section 35, respectively. The first balance weight 18, the second
balance weight 19, and the swirl flow generating portion 21 are
designed so that the relationship among these 1st to 3rd second
moments of area satisfies the following equation (2). This makes it
possible to make the swirl flow in the upper space 7 stronger and
the swirl flow in the lower space 5 weaker. The "second moment of
area of the first cross section 33" means a second moment of area
calculated using Equation (1) for the first cross section 33. This
also applies to the second cross section 34 and the third cross
section 35.
M.sub.A1+M.sub.A3>M.sub.A2 (2)
[0070] In the present embodiment, the swirl flow generating portion
21 has a plurality of baffle plates 122. Therefore, the second term
in the left-hand side of Equation (2) is represented as a sum of a
plurality of 3rd second moments of area of the plurality of baffle
plates 122. In the case where a plurality of first balance weights
18 are provided, the first term in the left-hand side of Equation
(2) is represented as a sum of a plurality of 1st second moments of
area of the plurality of first balance weights 18. Likewise, in the
case where a plurality of second balance weights 19 are provided,
the right-hand side of Equation (2) is represented as a sum of a
plurality of 2nd second moments of area of the plurality of second
balance weights 19.
[0071] In the present embodiment, the second balance weight 19 is
covered by a cover 22 to reduce the area of the second displacement
surface 19p of the second balance weight 19. The second
displacement surface 19p displaces the refrigerant. The area of the
second displacement surface 19p is substantially zero, if the
presence of screws or the like for fixing the cover 22 to the rotor
15 is ignored.
[0072] Therefore, the right-hand side of Equation (2) is zero and
thus the relationship of Equation (2) is satisfied.
[0073] The 1st second moment of area M.sub.A1 is equal to the
second moment of area of the first projected image on the first
plane, when the first plane is determined so that the area of the
first projected image has a maximum value. Likewise, the 2nd second
moment of area M.sub.A2 is equal to the second moment of area of
the second projected image on the second plane, when the second
plane is determined so that the area of the second projected image
has a maximum value. The 3rd second moment of area M.sub.A3 is
equal to the second moment of area of the third projected image on
the third plane, when the third plane is determined so that the
area of the third projected image has a maximum value.
[0074] Next, the flows of the refrigerant and the oil in the closed
casing 2 are described with reference to FIG. 9. In FIG. 9, the
flow of the refrigerant in the lower space 5, the flow of the
refrigerant in the upper space 7, and the flow of the oil returning
from the upper space 7 to the oil reservoir 3 are indicated by an
arrow 38a, an arrow 38b, and a dashed arrow 39, respectively. The
oil held in the oil reservoir 3 is used for lubrication and sealing
of the sliding parts of the compression mechanism 4. The compressed
refrigerant containing oil particles (oil mist) is discharged from
the compression mechanism 4 to the lower space 5 in a
high-temperature and high-pressure state. In the lower space 5, a
swirl flow field is formed by the rotation of the rotor 15, but the
intensity of the flow is reduced by the function of the cover 22,
compared to that in the upper space 7. The refrigerant discharged
into the lower space 5 is introduced from the lower space 5 to the
upper space 7 through the communication passages 20. The
refrigerant discharged into the upper space 7 is deflected in the
swirling direction and the outer peripheral direction by
centrifugal forces generated by the baffle plates 122 serving also
as the swirl flow generating portion 21 and the first balance
weight 18 as well as a flow deflecting action performed by the
baffle plates 122 serving also as the swirl flow generating portion
21. Since the refrigerant travels in the upper space 7 while
swirling, the oil particles are separated from the refrigerant by
the centrifugal forces during travelling. Then, the refrigerant is
discharged outside the closed casing 2 through the discharge pipe
8. The oil separated by the centrifugal forces in the upper space 7
adheres to the inner peripheral surface of the stator 14 or the
inner wall of the closed casing 2. Then, the oil returns to the oil
reservoir 3 through the air gap 16 or the flow path 17.
[0075] Next, the actions of the swirl flow generating portion
(baffle plate 122) and the swirl flow suppressing portion (cover
22) are described in detail.
[0076] First, a flow field generated by a swirl flow is described.
A model is assumed, in which a rotor 37a is placed in a cylindrical
container 37 and the rotor 37a is rotating about the central axis
O.sub.1 of the cylindrical container 37, as shown in FIG. 10. In
the cylindrical container 37, a pressure field 37b is generated
with a low pressure near the central axis O.sub.1 and a high
pressure near the inner peripheral surface of the cylindrical
container 37. This is the result of the effect of directing the
flow radially outwardly by the centrifugal force of the flow itself
and the effect of converting kinetic energy produced by swirling
into pressure energy near the inner peripheral surface of the
cylindrical container 37.
[0077] If the intensity of swirling increases, a pressure field 37c
indicated by a dashed line is generated. That is, the increase in
the intensity of swirling increases the centrifugal force of the
swirl flow itself. Therefore, the pressure field 37c tends to have
an even lower pressure near the central axis O.sub.1 of the
cylindrical container 37. On the other hand, kinetic energy
produced by swirling with the inclusion of additional kinetic
energy is converted into pressure energy near the inner peripheral
surface of the cylindrical container 37. Therefore, the pressure
field 37c tends to have an even higher pressure near the inner
peripheral surface of the cylindrical container 37.
[0078] In order to increase the swirl flow without changing the
rotational speed of the rotor 37a, it is necessary to increase the
displacement area of the rotor 37a and thus increase the momentum
added to the fluid. On the contrary, if the displacement area of
the rotor 37a is reduced, the swirl flow is suppressed.
[0079] In the present embodiment, from the viewpoint of preventing
whirling, the second balance weight 19 is heavier than the first
balance weight 18. Typically, the balance weights 18 and 19 are
made of a metal such as brass. In the case where the balance
weights 18 and 19 are made of the same material, the volume of the
second balance weight 19 must be greater than that of the first
balance weight 18 to make the second balance weight 19 heavier than
the first balance weight 18. In the case where the volume of the
second balance weight 19 is greater than that of the first balance
weight 18 and the cover 22 is not provided, the area of the
displacement surface 19p of the second balance weight 19 exceeds
the area of the displacement surface 18 of the first balance weight
18.
[0080] Next, the flows of refrigerant and oil in a rotary
compressor without a swirl flow generating portion and a swirl flow
suppressing portion are described with reference to FIG. 11. A
rotary compressor 100g shown in FIG. 11 does not have components
corresponding to the swirl flow generating portion (baffle plate
122) and the swirl flow suppressing portion (cover 22) in the
rotary compressor 100 of the present embodiment. Except for these
components, the configuration of the rotary compressor 100g is the
same as that of the rotary compressor 100 of the present
embodiment. That is, a first balance weight 18g and a second
balance weight 19g are each fixed to a rotor 15g and rotate with
the rotor 15g. The second balance weight 19g has a larger
displacement area than the first balance weight 18g. Therefore, the
swirl flow formed by the second balance weight 19g in a lower space
5g is stronger than that formed by the first balance weight 18g in
an upper space 7g.
[0081] In this case, as indicated by a dashed line 140b in FIG. 12,
a significant increase in pressure occurs in the opening of the
flow path 17g on the lower space 5g side, on the basis of the
theory described with reference to FIG. 10. As a result, as
indicated by an arrow 138 in FIG. 11, the refrigerant is more
likely to flow from the lower space 5g to the upper space 7g
through the flow path 17g.
[0082] On the other hand, the oil separated by a centrifugal force
in the upper space 7g reaches the inner wall of the closed casing
2g in the upper space 7g, and then returns to an oil reservoir 3g
by its own weight through the flow path 17g. However, if the
pressure in the opening of the flow path 17g on the lower space 5g
side is excessively higher than that in the opening of the flow
path 17g on the upper space 7g side, such a high pressure makes it
difficult for the oil to return smoothly through the flow path 17g.
That is, since the refrigerant travels from the lower space 5g to
the upper space 7g mainly through the flow path 17g, the flow of
the oil from the upper space 7g to the lower space 5g (indicated by
a dashed arrow 139) is impeded. As a result, the oil is likely to
accumulate near the inner wall of the closed casing 2g in the upper
space 7g. The accumulated oil is again mixed with the refrigerant
and discharged with the refrigerant outside the closed casing
2g.
[0083] In contrast, in the rotary compressor 100 of the present
embodiment, the swirl flow in the upper space 7 is increased by the
function of the swirl flow generating portion 21 while the swirl
flow in the loser space 5 is suppressed by the function of the
swirl flow suppressing portion 22. Therefore, as indicated by a
solid line 140a in FIG. 12, the pressure in the opening of the flow
path 17 on the upper space 7 side is higher than that in the
opening of the flow path 17 on the lower space 5 side, or the
difference between the pressure in the opening of the flow path 17
on the upper space 7 side and that in the opening of the flow path
17 on the lower space 5 side is relatively small.
[0084] Furthermore, as described with reference to FIG. 10, the
pressure near the center of the rotor 15 decreases when the swirl
flow is increased, while it increases when the swirl flow is
suppressed. When the swirl flow generating portion 21 is provided
in the upper space 7 and the swirl flow suppressing portion 22 is
provided in the lower space 5, the pressure near the center of the
rotor 15 becomes lower in the upper space 7 and higher in the lower
space 5. As a result, the amount of refrigerant flowing from the
lower space 5 to the upper space 7 through the communication
passage 20 increases, and the refrigerant can be prevented from
flowing from the upper space 7 to the lower space 5 through the
flow path 17, or the amount of refrigerant flowing from the lower
space 5 to the upper space 7 through the flow path 17 decreases
significantly. When the amount of refrigerant flowing from the
compression mechanism 4 to the discharge pipe 8 through the flow
path 17 decreases, the oil can be returned from the upper space 7
to the oil reservoir 3 smoothly through the flow path 17.
[0085] Next, consideration is given to a second moment of area.
[0086] Generally, the intensity of a swirl flow applied to a flow
field is determined by a swirl momentum Kr represented by the
following equation (3). In Equation (3), .rho. is the density of a
fluid, V is the rotational speed of a rotor, .omega. is the angular
velocity of the rotor, r is the turning radius of a displacement
portion (displacement surface) of the rotor, and A is the projected
area of the displacement portion (displacement surface) of the
rotor.
[Equation 3]
Kr=.rho.V.sup.2A=.rho.(r.omega.).sup.2A (3)
[0087] In Equation (3), assuming that the rotational speed V of the
rotor is far below 0.3 times the sound velocity in a refrigerant
flow, the refrigerant can be regarded as an incompressible fluid.
In this case, the density .rho. is constant. Furthermore, the
angular velocity .omega. also is constant under the same operating
conditions. As a result, the swirl momentum Kr that contributes to
the intensity of the swirl flow applied to the flow field is
proportional to a value obtained by multiplying the square of the
turning radius r by the projected area A. The value obtained by
multiplying the square of the turning radius r by the projected
area A corresponds to the second moment of area described above.
That is, the second moment of area represents the intensity of
swirling applied to the refrigerant flow. The smaller the second
moment of area, the smaller the intensity of swirling given to the
refrigerant flow. Therefore, when a strong swirl flow must be
generated in the upper space 7, the second moments of area of the
first balance weight 18 and the swirl flow generating portion 21
must be increased. When a swirl flow in the lower space 5 must be
suppressed, the second moment of area of the second balance weight
19 must be decreased using the swirl flow suppressing portion
22.
[0088] Next, the effect obtained by covering the outlet of the
communication passage 20 with the baffle plate 122 (discharge
direction deflecting portion) of the swirl flow generating portion
21 is described.
[0089] First, an example where nothing but a balance weight 18g is
provided on the top of a rotor 15g (in the compressor 100g shown in
FIG. 11), as shown in FIG. 13A and FIG. 13B, is described. In FIG.
13B, the rotational direction of the rotor 15g is considered as a
static system. Probably, a refrigerant flow 42g discharged from a
communication passage 20g to an upper space 7g collides with a
refrigerant flow 41g in the upper space 7g at an almost right
angle. In this case, a large pressure loss may occur. When a large
pressure loss occurs at the outlet of the communication passage
20g, the flow rate of the refrigerant flowing upward through the
communication passage 20g decreases relatively, while the flow rate
of the refrigerant flowing through the air gap 16g or the flow path
17g increases relatively. As described above, when the refrigerant
flow rate in the flow path 17g increases, the amount of oil
discharged from the compressor 100g also increases.
[0090] Next, an example where baffle plates 21g are disposed at the
outlets of the communication passages 20g, as shown in FIG. 14A and
FIG. 14B, is described. Each of the baffle plates 21g is located in
the rotational direction of the rotor 15g with respect to the
outlet of the communication passage 20g. The baffle plate 21g
extends straight in a direction parallel to the rotational axis O,
and thus does not cover the outlet of the communication passage
20g. Such a baffle plate 21g can prevent the refrigerant flow 42g
from colliding with the refrigerant flow 41g at a right angle. This
means that the pressure loss at the outlet of the communication
passage 20 can be reduced. It should be noted that the baffle plate
21g has no ability to deflect the refrigerant flow. Therefore, as
shown in FIG. 17, the refrigerant tends to flow upward in the
vertical direction.
[0091] Next, the present embodiment in which baffle plates 122 are
disposed to cover the outlets of the communication passages 20, as
shown in FIG. 15A and FIG. 15B, is described. Since a refrigerant
flow 42 discharged from the communication passage 20 to the upper
space 7 is subjected to the deflecting action of the baffle plate
122, the refrigerant is discharged in the opposite rotational
direction of the rotor 15. That is, the refrigerant travels from
the communication passages 20 to the upper space 7, while being
deflected in a direction inclined with respect to the direction
parallel to the rotational axis O. Then, as shown in FIG. 16, a
swirl flow begins to be formed at a position relatively close to
the upper surface of the rotor 15. As a result, the flow distance
(time) of the refrigerant in the upper space 7 increases, which can
promote the centrifugal separation of oil.
[0092] The baffle plate 122 may completely cover the outlet of the
communication passage 20 in plan view, or may partially cover it.
That is, a projected image obtained by projecting the baffle plate
122 onto the upper surface of the rotor 15 may contain the opening
area of the communication passage 20, or the projected image of the
baffle plate 122 may overlap the opening area. For example,
experimental results under high load conditions (a high rotational
speed and a high pressure ratio) show that an excellent effect is
obtained when the baffle plate 122 covers about 85% of the opening
area.
[0093] FIG. 18 is a graph showing the results of experiments
conducted to ascertain the effect of the rotary compressor 100 of
the present embodiment. The vertical axis represents the amount of
discharged oil. The experiments were conducted under high load
conditions, and the amount of oil discharged with the refrigerant
through the discharge pipe was measured. The amount of the
discharged oil was evaluated by sampling the refrigerant at the
outlet of a condenser in a refrigeration cycle. "Embodiment" shows
the measurement result in the rotary compressor described with
reference to FIG. 1, etc. "Comparative Example" shows the
measurement result in a rotary compressor in which the swirl flow
generating portion 21 and the swirl flow suppressing portion 22
(cover) of the rotary compressor of the embodiment are removed.
"First Modification" shows the measurement result in a rotary
compressor according to a first modification described later. The
amount of oil discharged from the rotary compressor of the present
embodiment was small, i.e., "0.44", when the amount of oil
discharged from the rotary compressor of Comparative Example was
"1". The amount of oil discharged from the rotary compressor of the
first modification described later was even smaller, i.e.,
"0.1".
First Modification
[0094] As shown in FIG. 19, in a rotary compressor 101 according to
the first modification, the inlet of the discharge pipe 8 is
located near the upper surface of the rotor 15. More specifically,
the lower end of the discharge pipe 8 is located below the upper
end of the stator 14 in the direction parallel to the rotational
axis O of the shaft 9 (i.e., the vertical direction). The
rotational axis O of the shaft 9 passes through the inlet of the
discharge pipe 8. More specifically, the rotational axis O of the
shaft 9 coincides with the center of the inlet of the discharge
pipe 8.
[0095] A refrigerant is discharged from the communication passage
20 to the upper space 7, and then travels, while swirling and being
deflected, toward the inner wall of the closed casing 2 by the
centrifugal force and the action of the baffle plates 122. Then,
the refrigerant goes downward along the outer peripheral surface of
the discharge pipe 8 while swirling and enters the discharge pipe
8. Since the flow distance (time) of the refrigerant flow in the
upper space 7 can be increased, the separation of oil can further
be promoted. Furthermore, since the refrigerant forms a downflow
immediately before it enters the discharge pipe 8, the oil
separation by the weight of the refrigerant itself also can be
promoted. As a result, as shown in FIG. 18, the amount of
discharged oil can further be reduced.
Second Modification
[0096] In a modification shown in FIG. 20, a space filling member
22b is used instead of the cover 22 as a swirl flow suppressing
portion. The space filling member 22b has a smaller specific
gravity than the second balance weight 19, and is provided along
the rotational trajectory of the second balance weight 19. That is,
the space filling member 22b is disposed symmetrically to the
second balance weight 19 with respect to a plane including the
rotational axis O, and fills the space along the trajectory of the
second balance weight 19. The area of the displacement surface of
the second balance weight 19 can be reduced by the space filling
member 22b, like the cover 22 described with reference to FIG. 1,
etc.
[0097] Preferably, the space filling member 22b is made of a
material having voids into which the refrigerant containing oil
particles can penetrate. Typically, the space filling member 22b
can be made of a material having voids, such as foamed materials,
metal fiber woven materials, and steel wool. Since these materials
are relatively light in weight, the function of the second balance
weight 19 as a balance weight is less likely to be impaired.
[0098] The shape of the space filling member 22b is not
particularly limited as long as the area of the displacement
surface of the second balance weight 19 can be reduced. In the
modification shown in FIG. 20, the shape of the space filling
member 22b is determined so that the area of the displacement
surface of the second balance weight 19 is substantially zero. The
area of the displacement surface of the space filling member 22b
also is zero. That is, a combination of the second balance weight
19 and the space filling member 22b forms an annular shape.
[0099] The refrigerant flow around the second balance weight 19
contains oil particles. The space filling member 22b is fixed to
the rotor 15, and rotates with the rotor 15. Therefore, a shear
flow is formed between the space filling member 22b and the
refrigerant flow. In the case where the space filling member 22b is
made of a material having voids such as a foamed material, oil
particles enter the foamed material due to turbulence in the
refrigerant flow, etc. Thereby, the space filling member 22b serves
as an oil mist trap.
[0100] As shown in FIG. 21, a discharge port 25 for discharging the
refrigerant compressed in the compression mechanism 4 to the lower
space 5 may be formed at a position where it overlaps the second
balance weight 19 and the space filling member 22b, that is, a
position where the discharge port 25 overlaps the rotational
trajectory of the second balance weight 19, in the direction
parallel to the rotational axis O (i.e., in the vertical
direction). In still other words, when the discharge port 25, the
second balance weight 19, and the space filling member 22b are
projected on a plane perpendicular to the rotational axis O, the
projected image of the discharge port 25 may overlap the projected
image of the second balance weight 19 and/or the projected image of
the space filling member 22b. In this configuration, the
refrigerant discharged to the lower space 5 through the discharge
port 25 can collide directly with the space filling member 22b. As
a result, the amount of oil particles entering the voids in the
space filling member 22b increase, and the oil separation effect of
the space filling member 22b can be sufficiently obtained.
Third Modification
[0101] As shown in FIG. 22, a cover 22c as a swirl flow suppressing
portion may be formed integrally with the end plate for clamping
and fixing the stack of steel plates 28 constituting the rotor 15.
Thereby, the number of components can be reduced. The cover 22c has
an annular shape in plan view. In the cover 22c, a plurality of
through-holes 44 are each formed at a position corresponding to the
inlet of the communication passage 20. The refrigerant can move
from the lower space 5 to the communication passages 20 through the
through-holes 44 and the interior of the cover 22c.
Fourth Modification
[0102] A swirl flow generating portion 146 shown in FIG. 23 has an
end plate 27 and a first balance weight 18 integrated with the end
plate 27. That is, the end plate 27 and the first balance weight 18
are formed as a single component by a casting method or the like.
This can reduce the number of components and simplify the assembly
process of the compressor.
[0103] The end plate 27 is caulked and fixed to the stack of steel
plates 28 to form the rotor 15. The communication passages 20 of
the rotor 15 are covered by roof portions 46 provided on the end
plate 27. The roof portion 46 constitutes a discharge direction
deflecting portion. One roof portion 46 is provided for one
communication passage 20. The roof portion 46 has walls above the
outlet of the communication passage 20, downstream thereof in the
rotational direction of the rotor 15, on the radially inner
peripheral side, and on the radially outer peripheral side. In
other words, the roof portion 46 has the shape of a small box with
an opening only in the opposite rotational direction of the rotor
15. The refrigerant is discharged from the communication passage 20
in the opposite rotational direction of the rotor 15 by the
function of the roof portions 46.
Fifth Modification
[0104] As shown in FIG. 24A, in the present modification, an outlet
part 48 of the communication passage 20 extends in a direction
inclined with respect to the direction parallel to the rotational
axis O of the motor 6. By the function of the outlet part 48, the
compressed refrigerant travels from the communication passage 20 to
the upper space 7, while being deflected in a direction that is
opposite to the rotational direction of the rotor 15 and is
inclined with respect to the direction parallel to the rotational
axis O. That is, the discharge direction deflecting portion is
constituted by the outlet part 48. Also in this modification, a
refrigerant flow 42 from the communication passage 20 does not
collide with a refrigerant flow 41 at a right angle in the upper
space 7. Therefore, an increase in the pressure loss at the outlet
of the communication passage 20 can be prevented.
[0105] FIG. 24A does not indicate a swirl flow generating portion
for increasing a swirl flow. However, the swirl flow generating
portion (for example, the baffle plate 122 shown in FIG. 3) may be
provided at a position where it does not cover the outlet of the
communication passage 20.
Sixth Modification
[0106] In a modification shown in FIG. 24B, a baffle plate 122
protruding obliquely from the upper surface of the rotor 15 so as
to extend in the same direction as the outlet part 48 is provided
as a swirl flow generating portion. An image obtained by projecting
the baffle plate 122 onto the upper surface of the rotor 15
overlaps the outlet of the communication passage 20. This means
that in this modification, both the outlet part 48 and the baffle
plate 122 have the function as a discharge direction deflecting
portion. This configuration ensures that a refrigerant flow from
the communication passage 20 is directed toward the opposite
rotational direction of the rotor 15. This configuration has the
potential to further reduce the pressure loss that occurs when the
refrigerant flow 42 is deflected.
[0107] The configurations of the first to sixth modifications can
be arbitrarily combined in the rotary compressor 100 shown in FIG.
1, without departing from the spirit and scope of the present
invention. Furthermore, the present invention is not limited to a
rotary compressor, and can be applied to other hermetic
compressors.
INDUSTRIAL APPLICABILITY
[0108] The hermetic compressor of the present invention is suitably
applicable to refrigeration cycle apparatuses used for air
conditioners, water heaters, etc. Since the flow of oil into a
condenser and an evaporator of a refrigeration cycle apparatus can
be reduced, the heat exchange efficiency of the condenser and the
evaporator can be improved.
* * * * *