U.S. patent application number 11/411400 was filed with the patent office on 2006-11-02 for compressor.
Invention is credited to Shingo Enami, Tetsuhiko Fukanuma, Masakazu Murase, Naoya Yokomachi.
Application Number | 20060245939 11/411400 |
Document ID | / |
Family ID | 36680223 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060245939 |
Kind Code |
A1 |
Fukanuma; Tetsuhiko ; et
al. |
November 2, 2006 |
Compressor
Abstract
A compressor includes a housing, a rotary shaft, a bearing, a
seal, a shaft seal chamber, a first passage, a second passage and
the fluid passage. The first passage connects a crank chamber to
the shaft seal chamber The second passage is formed between a lug
plate fixed to the rotary shaft and the housing so as to connect
the bearing to the crank chamber. The partition is provided in the
shaft seal chamber for dividing the shaft seal chamber into a
seal-side chamber and a bearing-side chamber. The first passage is
in communication with the seal-side chamber of the shaft seal
chamber. The fluid passage for accumulating the lubricating oil and
for communicating the first passage and the second passage is
formed radially inward of an inner circumferential surface of the
shaft seal chamber.
Inventors: |
Fukanuma; Tetsuhiko;
(Kariya-shi, JP) ; Yokomachi; Naoya; (Kariya-shi,
JP) ; Enami; Shingo; (Kariya-shi, JP) ;
Murase; Masakazu; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
3 World Financial Center
New York
NY
10281-2101
US
|
Family ID: |
36680223 |
Appl. No.: |
11/411400 |
Filed: |
April 25, 2006 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 39/0223 20130101;
F04B 27/109 20130101; F04B 53/18 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 27/08 20060101
F04B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 27, 2005 |
JP |
P2005-129753 |
Claims
1. A compressor comprising: a housing defining a crank chamber; a
rotary shaft at least one end of which extends out from the
housing; a bearing provided in the housing for rotatably supporting
the rotary shaft; a seal provided on the rotary shaft on an axially
outer side of the bearing for preventing refrigerant gas from
leaking out of the housing along the rotary shaft; a shaft seal
chamber defined by the seal, the bearing, the housing and the
rotary shaft; a first passage which connects the crank chamber to
the shaft seal chamber so that the refrigerant gas containing
therein lubricating oil in the crank chamber is drawn into the
shaft seal chamber; a second passage formed between a lug plate
fixed to the rotary shaft and the housing so as to connect the
bearing to the crank chamber; and a fluid passage for accumulating
the lubricating oil and for communicating with the first passage
and the second passage, the fluid passage being formed radially
inward of an inner circumferential surface of the shaft seal
chamber.
2. The compressor according to claim 1, further comprising: a
partition provided in the shaft seal chamber for dividing the shaft
seal chamber into a seal-side chamber and a bearing-side chamber;
wherein the first passage is in communication with the seal-side
chamber of the shaft seal chamber, the partition having the fluid
passage through which the refrigerant gas is drawn from the
seal-side chamber of the shaft seal chamber to the bearing-side
chamber of the shaft seal chamber which is in communication with
the second passage through the bearing.
3. The compressor according to claim 2, wherein the fluid passage
is formed between an inner circumferential surface of the partition
and an outer circumferential surface of the rotary shaft which
faces the inner circumferential surface.
4. The compressor according to claim 2, wherein the fluid passage
is a hole that extends through the partition.
5. The compressor according to claim 2, wherein the rotary shaft
includes a third passage which connects the bearing-side chamber of
the shaft seal chamber to a discharge pressure region thereby to
supply the refrigerant gas in the discharge pressure region to the
bearing-side chamber to be in contact with the partition.
6. The compressor according to claim 2, wherein the rotary shaft
includes a fourth passage which connects the bearing-side chamber
of the shaft seal chamber to the second passage thereby to supply
the refrigerant gas on the bearing-side chamber of the shaft seal
chamber to the second passage.
7. The compressor according to claim 1, wherein cross sectional
area of the fluid passage is smaller than that of the first
passage.
8. The compressor according to claim 1, wherein the bearing is a
plain bearing, the refrigerant gas in the shaft seal chamber being
drawn into the second passage through the fluid passage between an
inner circumferential surface of the plain bearing and an outer
circumferential surface of the rotary shaft.
9. A compressor comprising: a housing defining a crank chamber; a
rotary shaft at least one end of which extends out from the
housing; a bearing provided in the housing for rotatably supporting
the rotary shaft; a seal provided on the rotary shaft on an axially
outer side of the bearing for preventing refrigerant gas from
leaking out of the housing along the rotary shaft; a shaft seal
chamber defined by the seal, the bearing, the housing and the
rotary shaft; a first passage which connects the crank chamber to
the shaft seal chamber so that the refrigerant gas containing
therein lubricating oil in the crank chamber is drawn into the
shaft seal chamber; and a partition provided in the shaft seal
chamber for dividing the shaft seal chamber into a seal-side
chamber and a bearing-side chamber; wherein the rotary shaft
includes a fifth passage which connects the seal-side chamber of
the shaft seal chamber to a suction pressure region and which has a
throttle whose cross sectional area is smaller than that of the
first passage.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a compressor and in
particular to a peripheral structure of a seal for sealing a rotary
shaft of the compressor.
[0002] Japanese Unexamined Patent Application Publication (KOKAI)
No. 2004-176543 discloses a compressor where a housing including a
crank chamber has a cylindrical shaft hole through which a rotary
shaft extends and in which a shaft seal member is disposed for
sealing the rotary shaft. In this compressor, a recess is formed
around the shaft seal member and an oil passage is formed in the
housing for connecting the recess to the crank chamber, so that
lubricating oil which is drawn from the crank chamber into the oil
passage is collected in the recess. In addition, the compressor has
an injection circuit for supplying a part of refrigerant gas from
the crank chamber to the shaft seal member through the oil
passage.
[0003] Japanese Unexamined Patent Application Publication (KOKAI)
No. 2002-310067 discloses a compressor having a slide bearing
supporting a rotary shaft in a housing and a seal which is disposed
on the rotary shaft in the housing outside the slide bearing, so
that an isolated space is formed by and between the seal and the
slide bearing. In this compressor, an oil passage which provides
fluid communication between the isolated space and a crank chamber
is formed in the housing. In addition, the rotary shaft is pressed
against the slide bearing by a force derived from the compression
reaction force of the piston thereby to cause deflection of a
clearance between the rotary shaft and the bearing, so that an
increased portion of the clearance serves as an oil lubrication
passage between the isolated space and the crank chamber. By so
constructing the compressor, the isolated space between the seal
and the bearing and the crank chamber are made in communication
with each other by the two passages thereby to allow the
lubricating oil to circulate smoothly between the isolated space
and the crank chamber, with the result that troubles associated
with seizure between the seal and the rotary shaft are
prevented.
[0004] However, the space formed in the periphery of the shaft seal
member or seal (hereinafter referred to as "shaft seal chamber"),
such as the aforementioned recess or isolated space is provided
around the rotary shaft at a location near to the axial center of
the rotary shaft. On the other hand, the crank chamber from which
the lubricating oil is drawn into the shaft seal chamber is
provided around the rotary shaft at a location that is further from
the central axis of the rotary shaft than the shaft seal
chamber.
[0005] In operation of the compressor when rotating parts such as
the rotary shaft, a swash plate and a lug plate are being rotated,
a larger amount of lubricating oil is present in radially outer
region of the crank chamber under the influence of centrifugal
force, and therefore, only a less amount of lubricating oil is
present in the vicinity of the rotary shaft. This tendency is
especially notable during high-speed rotation period of the
compressor when lubrication of the seal is more important.
[0006] Since the lubricating oil in refrigerant gas in the crank
chamber exists in the form of mist, it is hard to draw a large
amount of the lubricating oil into the shaft seal chamber despite
the provision of the passage which connects the crank chamber to
the shaft seal chamber. Therefore, it is desirable that the
lubricating oil which has been drawn into the shaft seal chamber
should be retained therein as much as possible.
[0007] On the other hand, the lubricating oil which has been drawn
into the shaft seal chamber and remains therein is whirled with the
rotation of the rotary shaft, and therefore, a larger amount of the
lubricating oil exists in the periphery region of the shaft seal
chamber under the influence of centrifugal force.
[0008] The present invention is directed to a compressor which is
capable of effectively lubricating a seal which is provided for
preventing refrigerant gas from leaking out of a housing of the
compressor along the rotary shaft of the compressor.
SUMMARY OF THE INVENTION
[0009] A compressor according to the present invention provides the
following first features. The compressor includes a housing, a
rotary shaft, a bearing, a seal, a shaft seal chamber, a first
passage, a second passage and a fluid passage. The housing defines
a crank chamber. At least one end of the rotary shaft extends out
from the housing. The bearing is provided in the housing for
rotatably supporting the rotary shaft. The seal is provided on the
rotary shaft on an axially outer side of the bearing for preventing
refrigerant gas from leaking out of the housing along the rotary
shaft. The shaft seal chamber is defined by the seal, the bearing,
the housing and the rotary shaft. The first passage connects the
crank chamber to the shaft seal chamber so that the refrigerant gas
containing therein lubricating oil in the crank chamber is drawn
into the shaft seal chamber. The second passage is formed between a
lug plate fixed to the rotary shaft and the housing so as to
connect the bearing to the crank chamber. The fluid passage for
accumulating the lubricating oil and for communicating the first
passage and the second passage is formed radially inward of an
inner circumferential surface of the shaft seal chamber.
[0010] A compressor according to the present invention provides the
following second features. The compressor includes a housing, a
rotary shaft, a bearing, a seal, a shaft seal chamber, a first
passage and a partition. The housing defines a crank chamber. At
least one end of the rotary shaft extends out from the housing. The
bearing is provided in the housing for rotatably supporting the
rotary shaft. The seal is provided on the rotary shaft on an
axially outer side of the bearing for preventing refrigerant gas
from leaking out of the housing along the rotary shaft. The shaft
seal chamber is defined by the seal, the bearing, the housing and
the rotary shaft. The first passage connects the crank chamber to
the shaft seal chamber so that the refrigerant gas containing
therein lubricating oil in the crank chamber is drawn into the
shaft seal chamber. The partition is provided in the shaft seal
chamber for dividing the shaft seal chamber into a seal-side
chamber and a bearing-side chamber. The rotary shaft includes a
fifth passage which connects the seal-side chamber of the shaft
seal chamber to a suction pressure region and which has a throttle
whose cross sectional area is smaller than that of the first
passage.
[0011] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The features of the present invention that are believed to
be novel are set forth with particularity in the appended claims.
The invention together with objects and advantages thereof, may
best be understood by reference to the following description of the
presently preferred embodiments together with the accompanying
drawings in which:
[0013] FIG. 1 is a longitudinal sectional view showing a compressor
according to a first embodiment of the present invention;
[0014] FIG. 2 is a partial enlarged view showing a peripheral
structure of a shaft seal chamber of FIG. 1;
[0015] FIG. 3 is a partial enlarged view showing a peripheral
structure of a shaft seal chamber of a compressor according to a
second embodiment of the present invention;
[0016] FIG. 4 is a partial enlarged view showing a peripheral
structure of a shaft seal chamber of a compressor according to a
third embodiment of the present invention;
[0017] FIG. 5 is a partial enlarged view showing a peripheral
structure of a shaft seal chamber of a compressor according to a
fourth embodiment of the present invention; and
[0018] FIG. 6 is a longitudinal sectional view showing a compressor
according to a fifth embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The following will describe embodiments of a compressor
according to the present invention with reference to the
accompanying drawings. FIG. 1 is a longitudinal sectional view
showing a swash plate compressor 1 according to a first embodiment.
In FIG. 1, the left side of the drawing is the front side of the
compressor 1 and the right side of the drawing is the rear side of
the compressor 1.
[0020] The compressor 1 includes a cylinder block 2 and a front
housing 3 which is joined to the front end of the cylinder block 2
thereby to define a crank chamber 6. A rear housing 5 is joined to
the rear end of the cylinder block 2 through a valve plate assembly
4 therebetween.
[0021] A drive shaft 7 that serves as a rotary shaft is rotatably
provided in the crank chamber 6 at the center of the front housing
3 and the cylinder block 2. The drive shaft 7 is so arranged that a
front end of the drive shaft 7 extends out of the front housing 3.
The drive shaft 7 includes a first shaft portion 7a which is of a
hollowed cylindrical shape having one open end thereof and a second
shaft portion 7b which is also of a hollowed cylindrical shape but
having the opposite open ends and press-fitted in the first shaft
portion 7a, as shown in FIG. 1. An O ring 7c is interposed between
the inner circumferential surface of the first shaft portion 7a and
the outer circumferential surface of the second shaft portion 7b in
the vicinity of the front end of the second shaft portion 7b. A
passage 36 is formed between the inner circumferential surface of
the first shaft portion 7a and the outer circumferential surface of
the second shaft portion 7b. Additionally, an axial passage 26 is
formed axially in the second shaft portion 7b and the first shaft
portion 7a.
[0022] A lug plate 9 is fixed on the drive shaft 7 for rotation
therewith in the crank chamber 6. The drive shaft 7 is rotatably
supported at the front end portion thereof by a radial roller
bearing 39 which serves as a bearing for the rotary shaft and is
fitted in the front housing 3 on the front side of the lug plate 9.
The rear end of the drive shaft 7 is rotatably supported by a
radial roller bearing 40 which is fitted in the cylinder block 2. A
thrust bearing 10 is interposed between the lug plate 9 and the
inner sidewall of the front housing 3 thereby to rotatably support
the lug plate 9 relative to the front housing 3.
[0023] A swash plate 11 is provided on the drive shaft 7 on the
rear side of the lug plate 9 in such a way that the swash plate 11
is inclinable with respect to the drive shaft 7 while slidable in
axial direction of the drive shaft 7. A connecting portion 11a is
provided projecting from the swash plate 11 and a pair of guide
pins 12 is mounted at the distal end of the connecting portion 11a.
The pair of guide pins 12 engages with a pair of guide holes 9b in
the lug plate 9, respectively. A plurality of pistons 13 are
arranged around the drive shaft 7 and connected to the swash plate
11 through pairs of shoes 14, respectively. The pistons 13 are
received reciprocably in the respective cylinder bores 16 which are
formed in the cylinder block 2. As the swash plate 11 rotates, the
pistons 13 are reciprocated in the respective cylinder bores
16.
[0024] A lip seal 8 is provided on the drive shaft 7 on the front
side of the radial roller bearing 39 in the front housing 3 and
serves a seal for sealing the drive shaft 7. The lip seal 8
prevents the refrigerant gas and lubricating oil from leaking out
of the compressor 1 by flowing along the drive shaft 7 whose front
end extends out of the front housing 3. The lip seal 8, the radial
roller bearing 39, the front housing 3 and the drive shaft 7
cooperate to define a shaft seal chamber 30. A first passage 31 is
formed obliquely in the front housing 3 for fluid communication
between the shaft seal chamber 30 and the crank chamber 6. The
first passage 31 is so formed that the refrigerant gas containing
therein the lubricating oil in the crank chamber 6 is drawn into
the shaft seal chamber 30.
[0025] A partition 32 is provided in the shaft seal chamber 30 to
separate the lip seal 8 and the radial roller bearing 39, so that a
seal-side chamber 30a and a bearing-side chamber 30b are defined on
opposite sides of the partition 32, as clearly seen in FIGS. 1 and
2. The partition 32 has an annular disc shape, and as shown in FIG.
2, a fluid passage 42 is formed between an inner circumferential
surface 32a of the partition 32 and an outer circumferential
surface 7d of the drive shaft 7 which faces the inner
circumferential surface 32a. The fluid passage 42 has a dimension
of about 0.2-0.3 mm as measured in radial direction of the drive
shaft 7. The partition 32 is so positioned in the shaft seal
chamber 30 that the partition 32 does not prevent the first passage
31 and the seal-side chamber 30a of the shaft seal chamber 30 from
communicating with each other. In addition, the fluid passage 42 is
formed radially inward of an inner circumferential surface 30c of
the shaft seal chamber 30.
[0026] A second passage 33 is formed on the rear side of the radial
roller bearing 39 for fluid communication with the crank chamber 6.
The second passage 33 extends radially between the front housing 3
and the lug plate 9 and communicates with the crank chamber 6
through the thrust bearing 10. The radial roller bearing 39
includes a clearance which provides fluid communication between the
bearing-side chamber 30b in the shaft seal chamber 30 and the
second passage 33. Thus, the bearing-side chamber 30b communicates
with the crank chamber 6 through the above clearance in the radial
roller bearing 39, the second passage 33 and the thrust bearing 10.
In addition, a third passage 34 is formed obliquely in the drive
shaft 7 for fluid communication of the bearing-side chamber 30b of
the shaft seal chamber 30 with the axial passage 26 in the drive
shaft 7. The third passage 34 is in communication with a discharge
pressure region of the compressor as will be later described.
[0027] Referring back to FIG. 1, a discharge chamber 17 that
provides a part of the discharge pressure region of the compressor
is formed at the axial center of the rear housing 5 and connected
to external refrigerant circuit through an outlet (not shown). A
suction chamber 18 that provides a part of the suction pressure
region of the compressor is formed annularly in the outer
peripheral portion of the rear housing 5 and connected to the
external refrigerant circuit through an inlet (not shown). The
valve plate assembly 4 includes a suction port 19 and a suction
valve (not shown) for each cylinder bore 16 for selective
communication between the suction chamber 18 and each corresponding
cylinder bore 16. The valve plate assembly 4 also includes a
discharge port 20 and a discharge valve (not shown) for each
cylinder bore 16 for selective communication between each
corresponding cylinder bore 16 and the discharge chamber 17.
[0028] A control valve 21 is provided in the rear housing 5 for
adjusting the flow rate of the refrigerant gas flown into the crank
chamber 6 thereby to control the internal pressure in the crank
chamber 6 (crank chamber pressure Pc). The control valve 21 is in
communication with the discharge chamber 17 through a passage 21a,
as shown in FIG. 1. In the control valve 21, temperature of the
refrigerant gas from the discharge chamber 17 is lowered by a valve
portion having a throttle (not shown). The control valve 21 is also
in communication with a passage 22 which is formed in the rear
housing 5. The passage 22 is in turn in communication with a
passage 23 which is formed in the valve plate assembly 4. The
passage 23 is in communication with a passage 24 formed in the
cylinder block 2. The passage 24 is further in communication with
the axial passage 26 formed in the drive shaft 7 through an opening
25 formed in the center of the cylinder block 2. The passage 26 is
in communication with the third passage 34.
[0029] A passage 35 is formed in the drive shaft 7 at a position
between the swash plate 11 and the lug plate 9 for allowing part of
the refrigerant gas in the crank chamber 6 to flow therethrough to
the suction chamber 18. The passage 35 is in communication with a
passage 37 formed in the cylinder block 2 through the passage 36. A
lip seal 38 is disposed at the rear end of the drive shaft 7 in
such a way that a side of the passage 26 and a side of the passage
36 which are defined in the opening 25 are shut off from each
other. The passage 37 communicates with a passage 41 which is
formed in the valve plate assembly 4 and opened to the suction
chamber 18.
[0030] Now, operation of the swash plate compressor 1 according to
the first embodiment will be described with reference to FIGS. 1
and 2. As the drive shaft 7 is rotated by a drive source (not
shown), the swash plate 11 is rotated to cause each piston 13 to
slide reciprocally in each corresponding cylinder bore 16. The
refrigerant gas which circulates in the external refrigerant
circuit is drawn from the suction chamber 18 into each cylinder
bore 16 through each suction port 19 and is compressed in the
cylinder bore 16 by the piston 13. The compressed refrigerant gas
in the cylinder bore 16 is discharged into the discharge chamber 17
through each corresponding discharge port 20 and then circulates in
the external refrigerant circuit.
[0031] A part of the refrigerant gas in the discharge chamber 17 is
drawn into the crank chamber 6 through the control valve 21 thereby
to control the inclination of the swash plate 11 with respect to
the drive shaft 7. Flow rate of the refrigerant gas drawn into the
crank chamber 6 is changed by adjusting the opening degree of the
control valve 21. The flow of refrigerant gas passing through the
control valve 21 is throttled by the valve portion of the control
valve 21 thereby to lower the temperature of the refrigerant gas.
The refrigerant gas whose temperature has been thus lowered passes
through the passages 22, 23, 24, 25, 26 and 34 in this order and is
drawn into the bearing-side chamber 30b of the shaft seal chamber
30 so as to be in contact with the partition 32. Thereafter, the
refrigerant gas is drawn to the crank chamber 6 through the radial
roller bearing 39, the second passage 33 and the thrust bearing 10.
Thus, the pressure of the refrigerant gas in the crank chamber 6 is
adjusted as a crank chamber pressure Pc in accordance with the
opening degree of the control valve 21, and the inclination of the
swash plate 11 with respect to the drive shaft 7 is controlled by
the pressure difference between the crank chamber pressure Pc and
the internal pressure in each cylinder bore 16 thereby to adjust
the displacement of the swash plate compressor 1. That is, the
inclination of the swash plate 11 is changed by controlling the
crank chamber pressure Pc in the crank chamber 6. The refrigerant
gas in the crank chamber 6 passes through the passages 35, 36, 37
and 41 in this order and then is drawn into the suction chamber
18.
[0032] Now referring specifically to FIG. 2, behavior of the
refrigerant gas around the shaft seal chamber 30 will be described.
The refrigerant gas drawn into the crank chamber 6 contains therein
lubricating oil, which exists in the crank chamber 6 and the shaft
seal chamber 30 in the form of mist. In particular, when the lug
plate 8 and the swash plate 11 are rotated by the drive shaft 7,
oil attached on these parts is splashed radially outward, so that a
relatively large quantity of oil exists in the periphery region of
the crank chamber 6.
[0033] Since the lug plate 9 is rotated with the drive shaft 7, the
pressure in the second passage 33 and the bearing-side chamber 30b
of the shaft seal chamber 30 is reduced by the movement of the
refrigerant gas caused by the rotation of the lug plate 9. The
reduction of the pressure causes the refrigerant gas in the
seal-side chamber 30a of the shaft seal chamber 30 to be drawn into
the bearing-side chamber 30b through the fluid passage 42. At this
time, the refrigerant gas in the crank chamber 6 is drawn through
the first passage 31 into the seal-side chamber 30a of the shaft
seal chamber 30. Thus, the refrigerant gas in the periphery region
of the crank chamber 6 circulates flowing through the first passage
31, the seal-side chamber 30a of the shaft seal chamber 30, the
fluid passage 42, the bearing-side chamber 30b of the shaft seal
chamber 30, the clearance in the radial roller bearing 39, the
second passage 33 and the thrust bearing 10 in this order, thereby
forming a circulation passage for the refrigerant gas.
[0034] The fluid passage 42 in the shaft seal chamber 30 is formed
radially inward of inner circumferential surface 30c of the shaft
seal chamber 30. In addition, the refrigerant gas containing
therein the lubricating oil and drawn into the seal-side chamber
30a of the shaft seal chamber 30 is whirled in the seal-side
chamber 30a of the shaft seal chamber 30 with the rotation of the
drive shaft 7. The lubricating oil contained in the refrigerant gas
tends to accumulate in the vicinity of the inner circumferential
surface 30c of the shaft seal chamber 30 due to the influence of
centrifugal force. Since the refrigerant gas exists in the vicinity
of the drive shaft 7 where the fluid passage 42 is formed has a
smaller oil content, therefore, only less amount of oil is drawn
through the fluid passage 42 into the bearing-side chamber 30b, but
the refrigerant gas is drawn through the fluid passage 42 easily.
Thus, the lubricating oil drawn into the seal-side chamber 30a
tends to stay there. This tendency becomes noticeable when the
drive shaft 7 is rotated at a high speed. Since the lubricating oil
tends to stay in the chamber 30a adjacent to the lip seal 8,
lubrication of the lip seal 8 can be accomplished effectively.
[0035] In addition, since the cross sectional area of the fluid
passage 42 is smaller than that of the first passage 31, the
lubricating oil is easy to be drawn from the first passage 31 into
the seal-side chamber 30a of the shaft seal chamber 30, but it is
hard for the lubricating oil to be drawn from the seal-side chamber
30a of the shaft seal chamber 30 into the bearing-side chamber 30b
of the shaft seal chamber 30. Consequently, the lubricating oil is
supplied to the lip seal 8 efficiently.
[0036] Furthermore, since the refrigerant gas the flow of which has
been throttled by the valve portion of the control valve 21 to
lower the temperature thereof is supplied into the bearing-side
chamber 30b through the passage 34 in the drive shaft 7 to be in
contact with the partition 32, the partition 32 is cooled thereby
to cool the seal-side chamber 30a of the shaft seal chamber 30.
Therefore, the lip seal 8 located adjacent to the shaft seal
chamber 30 is also cooled. In addition, since the drive shaft 7 is
also cooled, the part of the drive shaft 7 which slides relative to
the lip seal 8 is prevented from being heated, so that the
temperature of the sliding portion of the lip seal 8 is
lowered.
[0037] A compressor according to a second embodiment is shown in
FIG. 3. In the following description of the second and other
embodiments, like reference numerals or symbols denote the like
elements or parts of the compressor used in the description of the
first embodiment and the detailed description of such elements or
parts will be omitted. The second embodiment uses a partition 50
which is different in structure from the partition 32 of the first
embodiment shown in FIG. 1. The partition 50 includes two fluid
passages 51 which have small hole shape through which the seal-side
chamber 30a and the bearing-side chamber 30b of the shaft seal
chamber 30 are in communication with each other. The fluid passages
51 are located radially inward of the inner circumferential surface
30c of the shaft seal chamber 30.
[0038] It is noted that the number of the fluid passages 51 may be
singular or plural and that a plurality of the fluid passages 51
may be arranged on the same circle of the cross sectional area. The
total of sectional areas of the fluid passages 51 formed in the
partition 50 is comparable to the cross section area of the fluid
passage 42 of the first embodiment. As long as the refrigerant gas
is drawn into the bearing-side chamber 30b of the shaft seal
chamber 30, the cross sectional area, the arrangement and the
number of the fluid passages 51 may be selected as desired. The
compressor of such a structure also provides effects similar to
those of the first embodiment.
[0039] A compressor according to a third embodiment is shown in
FIG. 4. The third embodiment is a modification of the first
embodiment and differs therefrom in the shape of the partition and
the passage in the drive shaft. Although the partition 60 has the
substantially the same shape as the partition 32 of the first
embodiment, the former partition 60 eliminates the fluid passage 42
of the first embodiment. The partition 60 is in contact with a
drive shaft 61 with little clearance therebetween. The drive shaft
61 has an axial communication passage 62 formed therein which
provides fluid communication between the seal-side chamber 30a of
the shaft seal chamber 30 and a suction chamber (not shown) which
corresponds to the suction chamber 18 of FIG. 1. The communication
passage 62, which is a fifth passage of the present invention,
connects the shaft seal chamber 30 to the suction pressure chamber
which is a part of the suction pressure region. In addition, a
throttle portion 63 is provided in the communication passage 62 to
reduce the cross sectional area of the communication passage 62.
The throttle portion 63 has a cross sectional area which is defined
to such an extent that allows the refrigerant gas in the seal-side
chamber 30a of the shaft seal chamber 30 to be drawn into the
suction pressure region. For example, the cross sectional area of
the throttle portion 63 may be comparable to the cross sectional
area of the fluid passage 42 of the first embodiment.
[0040] Since the communication passage 62 is in communication with
the suction-pressure region of the compressor, the pressure in the
communication passage 62 is lower than the pressure in the crank
chamber 6, so that pressure difference is arisen between the
communication passage 62 and the crank chamber 6 which the first
passage 31 communicates with. This pressure difference causes the
refrigerant gas in the crank chamber 6 in the vicinity of the first
passage 31 to be drawn into the seal-side chamber 30a of the shaft
seal chamber 30 and then be drawn toward the suction chamber
through the communication passage 62. Since the communication
passage 62 through which the refrigerant gas drawn into the
seal-side chamber 30a of the shaft seal chamber 30 is drawn is
formed radially inward of the inner circumferential surface 30c of
the shaft seal chamber 30, only less amount of the lubricating oil
is drawn from the seal-side chamber 30a of the shaft seal chamber
30 into the communication passage 62, but the refrigerant gas is
drawn into the communication passage 62 easily. Therefore, the
lubricating oil which has been drawn into the seal-side chamber 30a
of the shaft seal chamber 30 tends to remain in the seal-side
chamber 30a. In addition, since the throttle portion 63 is provided
in the communication passage 62, the lubricating oil is drawn
easily from the first passage 31 into the seal-side chamber 30a of
the shaft seal chamber 30, but it is difficult for the lubricating
oil to be drawn through the throttle portion 63 from the shaft seal
chamber side of the throttle portion 63 into the suction chamber
side of the throttle portion 63. Consequently, the lubricating oil
can be supplied efficiently to the lip seal 8. It is noted that the
throttle portion 63 may be provided in an area 62a of the
communication passage 62 in the vicinity of the lip seal 8. The
throttle portion 63 may also be provided in the area corresponding
to the valve plate assembly 4 shown in FIG. 1.
[0041] A compressor according to a fourth embodiment is shown in
FIG. 5. The fourth embodiment eliminates the partition 32 of the
first embodiment shown in FIG. 1, but uses a plain bearing 70 as a
slide bearing instead of the radial roller bearing 39 of the first
embodiment. The plain bearing 70 has a tubular shape and is fitted
in the front housing 3. As will be appreciated from comparison
between the drawings of FIGS. 2 and 5, the drive shaft 71 of the
fourth embodiment has no passage formed therein for communication
with the shaft seal chamber 30. A fluid passage 72 is formed
between the inner circumferential surface 70a of the tubular plain
bearing 70 and the outer circumferential surface 71a of the drive
shaft 71 which faces the inner circumferential surface 70a. The
fluid passage 72 is formed radially inward of the inner
circumferential surface 30c of the shaft seal chamber 30. The
dimension of the fluid passage 72 as measured in radial direction
is about 0.1 mm. The second passage 33 which is in communication
with the crank chamber 6 is formed on the rear side of the plain
bearing 70 as in the case of the first embodiment. The second
passage 33 extends radially between the front housing 3 and the lug
plate 9 and is in communication with the crank chamber 6 through
the thrust bearing 10.
[0042] In this fourth embodiment, the plain bearing 70 performs the
same function as the partition 32 of the first embodiment. That is,
the pressure in the second passage 33 is reduced by the movement of
the refrigerant gas caused by the rotation of the lug plate 9. The
reduction of the pressure causes the refrigerant gas in the shaft
seal chamber 30 to be drawn into the second passage 33 through the
fluid passage 72. Thus, the refrigerant gas in the periphery region
of the crank chamber 6 circulates flowing through the first passage
31, the shaft seal chamber 30, the fluid passage 72, the second
passage 33 and the thrust bearing 10 in this order, thereby forming
a circulation passage for the refrigerant gas. Consequently, the
effects similar to those of the first embodiment are obtained.
[0043] A compressor according to a fifth embodiment is shown in
FIG. 6. The fifth embodiment differs from the first embodiment in
that a passage of the refrigerant gas supplied from the shaft seal
chamber 30 is provided in a drive shaft 100, as shown in FIG. 6.
The drive shaft 100 includes an oblique hole 101 which is in
communication with the bearing-side chamber 30b of the shaft seal
chamber 30. A circular groove 102 is formed in the outer
circumferential surface of the drive shaft 100 on the rear side of
the radial roller bearing 39 for fluid communication with the hole
101. The circular groove 102 is also in communication with the
second passage 33. The hole 101 and the groove 102 form a fourth
passage of the present invention.
[0044] In the fifth embodiment, the low-temperature refrigerant gas
drawn into the bearing-side chamber 30b of the shaft seal chamber
30 is drawn through the drive shaft 100 while cooling the drive
shaft 100. Therefore, generating heat between the lip seal 8 and
the drive shaft 100 is prevented, so that the cooling effect of the
lip seal 8 can be further enhanced.
[0045] The partitions of the first, second and fifth embodiments
which are exposed to the low-temperature refrigerant gas from the
control valve 21 should be made of a material having a thermally
high conductivity, such as aluminum alloy, magnesium alloy or
copper for enhanced cooling effect of the lip seal 8.
[0046] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive, and the invention
is not to be limited to the details given herein but may be
modified within the scope of the appended claims.
* * * * *