U.S. patent application number 09/730576 was filed with the patent office on 2001-04-19 for screw compressor.
Invention is credited to Hida, Takeshi, Nozawa, Shigekazu, Urashin, Masayuki, Yamazaki, Noriyuki.
Application Number | 20010000320 09/730576 |
Document ID | / |
Family ID | 14180793 |
Filed Date | 2001-04-19 |
United States Patent
Application |
20010000320 |
Kind Code |
A1 |
Hida, Takeshi ; et
al. |
April 19, 2001 |
Screw compressor
Abstract
Oil separation from discharge gas of a screw compressor is
performed with a demister provided in a discharge chamber. For
solving unevenness in the speed distribution of the gas in the
chamber, at least one auxiliary demister for oil separation is
disposed at a local position immediately behind or near the
downstream side of an outlet of a discharge passage in a discharge
casing so as to be perpendicular to the flow direction of the gas
at the outlet. In addition, at least one obstacle plate is disposed
on the downstream side of the auxiliary demister.
Inventors: |
Hida, Takeshi; (Shimizu-shi,
JP) ; Nozawa, Shigekazu; (Shimizu-shi, JP) ;
Urashin, Masayuki; (Shimizu-shi, JP) ; Yamazaki,
Noriyuki; (Shimizu-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
14180793 |
Appl. No.: |
09/730576 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09730576 |
Dec 7, 2000 |
|
|
|
09287560 |
Apr 6, 1999 |
|
|
|
6183227 |
|
|
|
|
Current U.S.
Class: |
418/201.1 |
Current CPC
Class: |
F04C 29/026 20130101;
Y10S 418/01 20130101 |
Class at
Publication: |
418/201.1 |
International
Class: |
F04C 018/16; F04C
029/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 1998 |
JP |
10-097022 |
Claims
What is claimed is:
1. A screw compressor comprising a casing including at least one
pair of male and female rotors engaging with each other, an
electric drive motor and a bearing member; a discharge casing
provided with a discharge passage for gas and attached to said
casing; a discharge chamber provided therein with a main demister
for oil separation, a wall of said discharge chamber being joined
with said casing such that said discharge chamber contains said
discharge casing; and at least one auxiliary demister disposed at a
local position immediately behind or near the downstream side of an
outlet of said discharge passage so as to be perpendicular to the
flow direction of gas at said outlet.
2. A screw compressor according to claim 1, wherein at least one
obstacle plate is disposed on the downstream side of said auxiliary
demister.
3. A screw compressor comprising a discharge casing provided with a
discharge passage for gas compressed by male and female rotors
engaging with each other; a discharge chamber containing said
discharge casing; a main demister disposed in said discharge
chamber; and an auxiliary demister disposed on the upstream side of
said main demister in said discharge chamber so as to be opposite
to an outlet opening of said discharge passage.
4. A screw compressor according to claim 3, further comprising a
member disposed on the upstream side of said main demister in order
to uniformize each distribution of the speed and flow rate of
discharge gas from said discharge passage in said discharge
chamber.
5. A screw compressor according to claim 3, further comprising an
obstacle plate disposed between said auxiliary demister and said
main demister.
6. A screw compressor comprising a discharge casing provided with a
discharge passage for gas compressed by male and female rotors
engaging with each other; a discharge chamber containing said
discharge casing; a main demister disposed in said discharge
chamber; a frame disposed so as to cover an outlet opening of said
discharge passage; an obstacle member disposed in said frame such
that discharge gas from said discharge passage collides against
said obstacle member; and an auxiliary demister disposed on the
upstream side of said obstacle member in said frame.
7. A screw compressor according to claim 6, wherein a mesh-like
demister is disposed as said main demister so as to contain the
whole of a cross section of said discharge chamber.
Description
BACKGROUND OF THE INVENTION
1. The present invention relates to a screw compressor,
particularly to a screw compressor with a simple construction
suitable for efficiently separating oil from discharge gas.
2. In a conventional screw compressor, as disclosed in Japanese
Patent Unexamined Publication No. 10283/1993, a mesh demister is
provided in a discharge chamber such that the former includes the
whole of a cross section of the latter. There is such a structure
that discharge gas discharged from a discharge casing into the
chamber is passed through the mesh demister to separate oil
contained in the discharged gas.
3. The efficiency of such a mesh demister separating oil is
connected with the speed of gas passing. Either of the speed and
flow rate of gas discharged into the discharge chamber has a
distribution in a cross section of the chamber. So the gas passes
through the mesh demister at uneven speeds and flow rates. More
specifically, either of the speed and flow rate near the outlet of
a discharge passage of the discharge casing is greater than that of
the other parts.
4. That is, in the whole of the mesh demister, the flow rate in the
downstream part of the discharge outlet is great but the speed
therein is far from the optimum passing speed for the mesh
demister. This causes a problem of remarkably reducing the oil
separation efficiency. For solving this problem, some measures were
hitherto conventionally taken, e.g., an obstacle plate is provided
independently in the chamber or modifying flow passage of discharge
gas to change the direction of gas flow and thereby make the flow
rate distribution in the chamber even.
5. However, those measures also have such problems as that the
fixing portion of the independent obstacle plate is apt to be
damaged, oil scatters again immediately after colliding, and the
performance of the compressor deteriorates with an increase in
pressure loss due to change of the flow direction.
SUMMARY OF THE INVENTION
6. The present invention is made in view of the above-mentioned
problems, and it is an object of the present invention to provide a
screw compressor with a simple construction, high efficiency of
separating oil from discharge gas, and a small amount of oil
entrained out of the compressor.
7. A screw compressor as achieves the object of the present
invention comprises a casing including at least one pair of male
and female rotors engaging with each other, an electric drive motor
and a bearing member; a discharge casing provided with a discharge
passage for gas and attached to the casing; a discharge chamber
provided therein with a main demister for oil separation, a wall of
said discharge chamber being joined with the casing such that the
discharge chamber contains the discharge casing; and at least one
auxiliary demister disposed at a local position immediately behind
or near the downstream side of an outlet of the discharge passage
so as to be perpendicular to the flow direction of gas at the
outlet.
8. At least one obstacle plate may be disposed on the downstream
side of the auxiliary demister.
9. According to another aspect of the present invention, a screw
compressor comprises a discharge casing provided with a discharge
passage for gas compressed by male and female rotors engaging with
each other; a discharge chamber containing the discharge casing; a
main demister disposed in the discharge chamber; and an auxiliary
demister disposed on the upstream side of the main demister in the
discharge chamber so as to be opposite to an outlet opening of the
discharge passage. A member may be disposed on the upstream side of
the main demister in order to uniformize each distribution of the
speed and flow rate of discharge gas from the discharge passage in
the discharge chamber. An obstacle plate may be disposed between
the auxiliary and main demisters.
10. According to another aspect of the present invention, a screw
compressor comprises a discharge casing provided with a discharge
passage for gas compressed by male and female rotors engaging with
each other; a discharge chamber containing the discharge casing; a
main demister disposed in the discharge chamber; a frame disposed
so as to cover an outlet opening of the discharge passage; an
obstacle member disposed in the frame such that discharge gas from
the discharge passage collides against the obstacle member; and an
auxiliary demister disposed on the upstream side of the obstacle
member in the frame. A mesh-like demister is desirably disposed as
the main demister so as to contain the whole of a cross section of
the discharge chamber.
11. Other and further objects, features and advantages of the
invention will be apparent from the following description taken in
connection with the accompanying drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
12. FIG. 1 is a sectional view of a screw compressor according to
an embodiment of the present invention;
13. FIG. 2 is an enlarged sectional view of an auxiliary demister
portion of the compressor of FIG. 1;
14. FIG. 3 is a detail view partly insection view of another
example of auxiliary demister portion of the compressor of FIG.
1;
15. FIG. 4 is a detail view partly insection of another example of
auxiliary demister portion of the compressor of FIG. 1; and
16. FIG. 5 is a detail view partly in section of a modification of
the auxiliary demister portion of the compressor of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
17. Hereinafter, an embodiment of the present invention will be
described with reference to drawings. FIG. 1 shows the construction
in cross section of a screw compressor according to the embodiment.
FIG. 2 shows an example of auxiliary demister provided in a
discharge chamber of the screw compressor of FIG. 1.
18. Referring to FIG. 1, the screw compressor comprises a casing 1,
a motor cover 2 with an inlet 8 for suction, a discharge casing 3,
and a discharge chamber 4 with an outlet 14 for discharge. The
casing 1, motor cover 2 and discharge casing 3 and the wall of the
discharge chamber 4 are hermetically joined with each other. The
casing 1 receives an electric drive motor 7 therein and is provided
with a cylindrical bore 16 and a suction port 9 for introducing gas
into the bore 16.
19. The cylindrical bore 16 receives therein a male rotor 6
supported by roller bearings 10, 11 and 12 and ball bearings 13 so
as to be rotatable, and a not-shown female rotor engaging with the
male rotor 6. The male rotor 6 is directly joined to the electric
drive motor 7.
20. The discharge casing 3 includes the roller bearing 12 and ball
bearings 13. A cover plate 19 for closing a bearing chamber 18
containing the roller bearing 12 and ball bearings 13 is attached
to one end of the discharge casing 3. The discharge casing 3 is
fixed to the casing 1 by means of a bolt or the like.
21. In the discharge casing 3, a discharge passage 15 for gas is so
formed as to communicate with the cylindrical bore 16 through a
discharge port 17. An outlet of the passage 15 is opened in the
discharge chamber 4.
22. A main demister 5 is provided in the discharge chamber 4. An
auxiliary demister 21 and an obstacle plate 22 are attached to the
main demister 5 by means of a tying wire 23. For attaching the
auxiliary demister 21 and obstacle plate 22, welding shown in FIG.
3 for example or a fixing element 25 such as a split pin shown in
FIG. 4 for example can be employed. For this purpose, any means may
be employed if they are fixed at their specific positions.
23. The wall of the discharge chamber 4 is fixed to the casing 1 by
means of a bolt or the like to surround the discharge casing 3.
Lubricating oil is stored in the bottom of the discharge chamber 4.
In the casing 1 and discharge casing 3, passages for feeding oil
are formed such that the lower portion of the discharge chamber 4
communicates with each bearing.
24. Next, flows of coolant gas and oil will be described. Coolant
gas at a low temperature and a low pressure sucked through the
suction inlet 8 provided in the motor cover 2, passes through a gas
passage formed between the electric drive motor 7 and casing 1, and
air gaps between the stator and rotor of the motor 7 to cool the
motor 7. The gas is then sucked into compression chambers formed by
engaging surfaces of the male and female screw rotors and the
casing 1.
25. With rotation of the male rotor 6 directly joined to the
electric drive motor 7, the coolant gas is confined in each
compression chamber and compressed gradually by contraction of the
compression chamber to be at a high temperature and a high
pressure. The gas is then introduced into the discharge passage 15
through the discharge port 17 provided in the discharge casing 3 to
be discharged in the discharge chamber 4.
26. In the compression reaction forces acting on the male and
female screw rotors at the time of compression, the radial load is
borne by the roller bearings 10, 11 and 12 and the thrust load is
borne by the ball bearings 13. Oil for lubricating and cooling
those bearings is fed from an oil reservoir provided in a
high-pressure portion in the casing 1 and passes through the oil
passages communicating with the respective bearings. This feeding
of oil is done due to differential pressure. The oil is then
discharged in the discharge chamber 4 with compressed gas.
27. In the discharge chamber 4, the oil contained in the compressed
gas passes through the auxiliary demister 21 attached to the main
demister 5, and then collides against the obstacle plate 22. The
first separation of oil is thereby performed. The auxiliary
demister 21 has functions of collecting a part of oil while the
discharge gas passes through it, and preventing oil from scattering
when the oil collides against the obstacle plate 22 and is
separated from the gas.
28. The flow of the discharge gas is made even in the discharge
chamber 4 by passing through the auxiliary demister 21 and
colliding against the obstacle plate 22. The gas then passes
through the main demister 5 to separate the remaining oil from the
gas. Separated oil is again stored in the oil reservoir in the
lower portion of the casing 1. After the separation of oil, the
compressed coolant gas is discharged from the compressor through
the discharge outlet 14.
29. Even in case of an obstacle plate 22 made of a flat plate or a
punching metal, a similar effect of separation by collision can be
obtained. The shape of each of the auxiliary demister 21 and
obstacle plate 22 may be a circle, a rectangle or any other
shape.
30. FIG. 5 shows another embodiment of the present invention whose
basic construction is the same as that of the first embodiment
described above. In this embodiment, a frame 24 is attached to the
cover plate 19 by means of a bolt or the like such that the frame
24 covers the opening of the discharge passage 15 for the discharge
chamber 4.
31. The bottom wall of the frame 24 is made of a flat plate or a
punching metal to separate oil from discharge gas by collision. In
the frame 24, the auxiliary demister 21 is disposed for collecting
a part of oil while the discharge gas passes through it, and
preventing oil from scattering at the time of collision.
32. According to the present invention, at least one auxiliary
demister is disposed at a local position immediately behind or near
the downstream side of an outlet of a discharge passage in a
discharge casing, and desirably, at least one obstacle plate is
disposed on the downstream side of the auxiliary demister. As a
result, a screw compressor can be obtained with high efficiency of
oil separation and so a small amount of oil entrained out of the
compressor.
* * * * *