U.S. patent application number 12/708118 was filed with the patent office on 2010-09-30 for screw compressor.
This patent application is currently assigned to Hitachi Appliances, Inc.. Invention is credited to Eisuke KATO, Kenji Tojo, Masayuki Urashin, Shinichiro Yamada, Ryuichiro Yonemoto.
Application Number | 20100247366 12/708118 |
Document ID | / |
Family ID | 42770832 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100247366 |
Kind Code |
A1 |
KATO; Eisuke ; et
al. |
September 30, 2010 |
Screw compressor
Abstract
In order to obtain a screw compressor which is small in size and
weight and has ease of maintenance and high reliability, the screw
compressor comprises a screw rotor, a low-pressure-side bearing and
a high-pressure-side bearing which support the screw rotor, a motor
which drives the screw rotor, a motor casing which accommodates the
motor, a main casing which accommodates the screw rotor and the
low-pressure-side bearing, and a discharge casing which
accommodates the high-pressure-side bearing. The motor casing, the
main casing, and the discharge casing are accommodated in a steel
pipe chamber, and the steel pipe chamber includes a
low-pressure-side chamber and a high-pressure-side chamber which
are able to be divided in the axial direction. By using a flange
provided on an inner surface of the steel pipe chamber, a flange
provided in the main casing, and a sealing component provided
between the flanges, the steel pipe chamber is divided into a
low-pressure-side space and a high-pressure-side space.
Inventors: |
KATO; Eisuke; (Shizuoka,
JP) ; Urashin; Masayuki; (Shizuoka, JP) ;
Yonemoto; Ryuichiro; (Shizuoka, JP) ; Yamada;
Shinichiro; (Yaizu, JP) ; Tojo; Kenji;
(Moriya, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET, SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Assignee: |
Hitachi Appliances, Inc.
|
Family ID: |
42770832 |
Appl. No.: |
12/708118 |
Filed: |
February 18, 2010 |
Current U.S.
Class: |
418/201.1 |
Current CPC
Class: |
F04C 18/16 20130101;
F04C 23/008 20130101; F01C 21/10 20130101 |
Class at
Publication: |
418/201.1 |
International
Class: |
F04C 18/16 20060101
F04C018/16 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2009 |
JP |
2009-073072 |
Claims
1. A screw compressor comprising: a screw rotor which includes a
toothed portion and a shaft portion; a low-pressure-side bearing
and a high-pressure-side bearing which support the shaft portion of
said screw rotor; a driving motor which is directly connected to
the shaft portion of said screw rotor; a motor casing which
accommodates the motor; a main casing which accommodates said screw
rotor and said low-pressure-side bearing; a discharge casing which
accommodates the high-pressure-side bearing of said screw rotor;
and a steel pipe chamber which accommodates said motor casing, said
main casing and said discharge casing, wherein said steel pipe
chamber includes a low-pressure-side chamber and a
high-pressure-side chamber which are able to be divided in an axial
direction, and wherein a space inside said steel pipe chamber is
divided into a low-pressure-side space and a high-pressure-side
space through a flange provided in an inner surface of the steel
pipe chamber, a flange provided in said main casing or said motor
casing, and a sealing component provided between said flanges.
2. The screw compressor according to claim 1, wherein said
low-pressure-side chamber and said high-pressure-side chamber are
connected to each other through flanges provided in outer-surface
ends thereof, so that the inside of the steel pipe chamber is
sealed from an ambient air.
3. The screw compressor according to claim 2, wherein said
high-pressure-side chamber is divided into two parts in the axial
direction so as to form a first high-pressure-side chamber
connected to said low-pressure-side chamber and a second
high-pressure-side chamber connected to the first
high-pressure-side chamber, and wherein the first and second
high-pressure-side chambers are connected to each other through
flanges provided in outer-surface ends thereof, so that the inside
of the steel pipe chamber is sealed from the ambient air.
4. The screw compressor according to claim 1, wherein said flange
provided on the inner surface of said high-pressure-side chamber is
connected to said flange provided in said main casing through said
sealing component, so that a space inside the steel pipe chamber is
divided into a low-pressure-side space and a high-pressure-side
space.
5. The screw compressor according to claim 1, wherein said flange
provided on the inner surface of said high-pressure-side chamber is
connected to said flange provided in said motor casing through said
sealing component, so that said space inside said steel pipe
chamber is divided into the low-pressure-side space and the
high-pressure-side space.
6. The screw compressor according to claim 1, wherein said flange
provided in the inner surface of said low-pressure-side chamber is
connected to said flange provided in said main casing through the
sealing component, so that the space inside said steel pipe chamber
is divided into the low-pressure-side space and the
high-pressure-side space.
7. The screw compressor according to claim 1, wherein said flange
provided in the inner surface of said low-pressure-side chamber is
connected to said flange provided in said motor casing through the
sealing component, so that the space inside said steel pipe chamber
is divided into the low-pressure-side space and the
high-pressure-side space.
8. The screw compressor according to claim 1, wherein a central
axis of a shell constituting said steel pipe chamber is disposed in
a horizontal direction.
9. The screw compressor according to claim 1, wherein said screw
rotor includes at least a pair of male and female rotors meshing
with each other.
10. The screw compressor according to claim 9, wherein an operation
fluid to be compressed is a refrigerant used in a refrigeration
cycle, wherein a refrigerant having a cooling ability per unit
volume flow rate equal to or less than 70% of R407C is used,
wherein the number of teeth of the male rotor of said screw rotor
is set to four, and the number of teeth of said female rotor
thereof is set to six, and wherein the driving motor directly
connected to said male rotor is driven by an inverter.
11. The screw compressor according to claim 9, wherein a central
axis of said steel pipe chamber is disposed between a central axis
of said male rotor and a central axis of said female rotor.
12. The screw compressor according to claim 1, further comprising:
a gate rotor which meshes with said screw rotor; and a bearing
which supports a shaft portion of said gate rotor.
13. A screw compressor comprising: a screw rotor which includes a
toothed portion and a shaft portion; a gate rotor which meshes with
said screw rotor; a low-pressure-side bearing and a
high-pressure-side bearing which support the shaft portion of said
screw rotor; a bearing which supports a shaft portion of said gate
rotor; a driving motor which is directly connected to the shaft
portion of said screw rotor and drives said screw rotor; a motor
casing which accommodates said motor; a main casing which
accommodates said screw rotor and said gate rotor; and a steel pipe
chamber which accommodates said motor casing and said main casing,
wherein said steel pipe chamber includes a low-pressure-side
chamber and a high-pressure-side chamber which are able to be
divided in an axial direction, and wherein a space inside said
steel pipe chamber is divided into a low-pressure-side space and a
high-pressure-side space through a flange provided on an inner
surface of said steel pipe chamber, a flange provided in said main
casing or said motor casing, and a sealing component provided
between said flanges.
14. A screw compressor comprising: a screw rotor; a bearing which
supports said screw rotor; a motor which drives said screw rotor; a
motor casing which accommodates said motor; a main casing which
accommodates said screw rotor; and a steel pipe chamber which
accommodates said motor casing and said main casing, wherein said
steel pipe chamber is able to be divided in an axial direction, and
wherein a space inside said steel pipe chamber which is able to be
divided is divided into a low-pressure-side space and a
high-pressure-side space through a sealing component.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a screw compressor which
compresses a fluid, and particularly, to a screw compressor which
is used in a refrigeration cycle of an air conditioner, a
refrigerating machine, or the like.
DESCRIPTION OF RELATED ART
[0002] In a screw compressor, a screw rotor having a
three-dimensionally twisted curved surface is provided as a
compression mechanism portion. For this reason, generally, a casing
accommodating the compression mechanism portion is made from cast
iron which is able to be formed in a complex shape. The cast iron
generally used for the casing of the compressor has strength lower
than that of steel for pressure pipe. In the case where a design
pressure is the same, the cast iron casing needs to be thicker than
the steel casing. For this reason, there is a problem in that the
mass of the compressor increases. In addition, in the screw
compressor, lubricant contained in a discharge gas needs to be
separated. For this reason, in many cases, an oil separator is
integrally formed with the compressor. At this time, since the oil
separator is also made from cast iron, there is a problem in that
the mass of the compressor largely increases.
[0003] Meanwhile, in order to decrease the size and weight of the
screw compressor, a method may be supposed in which a compression
mechanism portion is accommodated in a steel pipe chamber as in a
rotary compressor or a scroll compressor. For example, in U.S. Pat.
No. 4,545,742, a structure is disclosed in which a compression
mechanism portion of a screw compressor is accommodated in a steel
pipe chamber. In this related art, a configuration is adopted in
which a pressure inside the steel pipe chamber is set to a high
pressure.
[0004] In addition, in another related art, a screw compressor is
supposed in which a cast iron compression mechanism portion is
accommodated in a steel pipe chamber, and different types of
metals, that is, the cast iron and the steel pipe are welded to
each other so as to divide the inside of the steel pipe chamber
into a low pressure portion and a high pressure portion.
[0005] When the steel pipe chamber is adopted in the screw
compressor, it is possible to realize a decrease in size and
weight. However, the screw compressors of the related art have the
following problems.
[0006] In the case where the pressure inside the steel pipe chamber
is raised to a high pressure after compressing a refrigerant gas, a
motor is cooled by a high-temperature and high-pressure refrigerant
gas. Due to this, there is a problem in that the motor may be
overheated during an operation of the compressor, and the
reliability thereof is not satisfactory. On the contrary, the
pressure inside the steel pipe chamber may be dropped to a low
pressure before compressing the refrigerant gas. However, in the
configuration in which the pressure inside of the steel pipe
chamber is dropped to a low pressure, it is difficult to install an
oil separator in the steel pipe chamber. For this reason, it is
necessary to install the oil separator separately from the
compressor, and hence there is a problem in that the entire
compressor increases in size.
[0007] In addition, in the case of the structure in which different
types of metals, that is, the steel pipe and the cast iron are
welded to each other so as to obtain the low pressure portion and
the high pressure portion divided from each other, the different
types of metals can be welded to each other, but when the optimal
welding condition is not set, cracks occur due to the insufficient
welding penetration of the welded portion, and then a gas leakage
or a leakage of a high-pressure refrigerant gas to the low pressure
portion occurs, which causes a problem in that the performance
thereof is degraded. In addition, in this structure, since it is
necessary to weld the entire circumference of the steel pipe
chamber so as to form the low pressure portion and the high
pressure portion divided from each other, the weld length is long.
For this reason, there is a problem in that a potential of causing
cracks in the welded portion increases, and this structure is
difficult to be applied to a high capacity compressor. In addition,
when this structure is adopted, the compressor becomes a hermetic
structure, and hence there is a problem in that maintenance such as
an exchange of a bearing cannot be performed.
[0008] As described above, in the structure in which the steel pipe
chamber accommodates the compression mechanism portion of the screw
compressor, it is difficult to dispose the motor on the low
pressure side and to dispose the oil separator on the high pressure
side after making the compressor in a semi-hermetic state. That is,
although the steel pipe chamber structure is a remarkable structure
in small size and weight, there is a problem in that ease of
maintenance and reliability are degraded.
SUMMARY OF THE INVENTION
[0009] An object of the invention is to obtain a screw compressor
which is small in size and weight and has ease of maintenance and
high reliability.
[0010] In order to attain the above-described object, according to
an aspect of the invention, there is provided a screw compressor
including: a screw rotor which includes a toothed portion and a
shaft portion; a low-pressure-side bearing and a high-pressure-side
bearing which support the shaft portion of the screw rotor; a
driving motor which is directly connected to the shaft portion of
the screw rotor; a motor casing which accommodates the motor; a
main casing which accommodates the screw rotor and the
low-pressure-side bearing; a discharge casing which accommodates
the high-pressure-side bearing of the screw rotor; and a steel pipe
chamber which accommodates the motor casing, the main casing, and
the discharge casing, wherein the steel pipe chamber includes a
low-pressure-side chamber and a high-pressure-side chamber which
are able to be divided in the axial direction, and wherein a space
inside the steel pipe chamber is divided into a low-pressure-side
space and a high-pressure-side space through a flange provided in
an inner surface of the steel pipe chamber, a flange provided in
the main casing or the motor casing, and a sealing component
provided between the flanges.
[0011] Here, the low-pressure-side chamber and the
high-pressure-side chamber may be connected to each other through
flanges provided in outer-surface ends thereof, so that the inside
of the steel pipe chamber is sealed from an ambient air. The
high-pressure-side chamber may be further divided into two parts in
the axial direction so as to form a first high-pressure-side
chamber connected to the low-pressure-side chamber and a second
high-pressure-side chamber connected to the first
high-pressure-side chamber, and the first and second
high-pressure-side chambers may be preferably connected to each
other through flanges provided in outer-surface ends thereof, so
that the inside of the steel pipe chamber is sealed from the
ambient air.
[0012] In addition, the flange provided on the inner surface of the
high-pressure-side chamber may be connected to the flange provided
in the main casing through the sealing component, the flange
provided in the inner surface of the high-pressure-side chamber may
be connected to the flange provided in the motor casing through the
sealing component, the flange provided on the inner surface of the
low-pressure-side chamber may be connected to the flange provided
in the main casing through the sealing component, or the flange
provided on the inner surface of the low-pressure-side chamber is
connected to the flange provided in the motor casing through the
sealing component, so that the space inside the steel pipe chamber
is divided into the low-pressure-side space and the
high-pressure-side space.
[0013] A central axis of a shell constituting the steel pipe
chamber may be preferably disposed in the horizontal direction.
[0014] The screw rotor according to the invention may preferably
include at least a pair of male and female rotors meshing with each
other. In addition, when as an operation fluid to be compressed in
the compressor according to the invention, which is a refrigerant
used in a refrigeration cycle, a refrigerant having a cooling
ability per unit volume flow rate equal to or less than 70% of
R407C is used, the number of teeth of the male rotor of the screw
rotor is set to four, the number of teeth of the female rotor
thereof is set to six, and then the driving motor directly
connected to the male rotor is driven by an inverter, it is
possible to use a refrigerant (a low GWP refrigerant) having a low
global warming potential.
[0015] In addition, a central axis of the steel pipe chamber may be
disposed between a central axis of the male rotor and a central
axis of the female rotor.
[0016] Further, the screw compressor may further be applied to one
including a gate rotor which meshes with the screw rotor; and a
bearing which supports a shaft portion of the gate rotor.
[0017] According to another aspect of the invention, there is
provided a screw compressor including: a screw rotor which includes
a toothed portion and a shaft portion; a gate rotor which meshes
with the screw rotor; a low-pressure-side bearing and a
high-pressure-side bearing which support the shaft portion of the
screw rotor; a bearing which supports a shaft portion of the gate
rotor; a driving motor which is directly connected to the shaft
portion of the screw rotor and drives the screw rotor; a motor
casing which accommodates the motor; a main casing which
accommodates the screw rotor and the gate rotor; and a steel pipe
chamber which accommodates the motor casing and the main casing,
wherein the steel pipe chamber includes a low-pressure-side chamber
and a high-pressure-side chamber which are able to be divided in
the axial direction, and wherein a space inside the steel pipe
chamber is divided into a low-pressure-side space and a
high-pressure-side space through a flange provided on an inner
surface of the steel pipe chamber, a flange provided in the main
casing or the motor casing, and a sealing component provided
between the flanges.
[0018] According to still another aspect of the invention, there is
provided a screw compressor including: a screw rotor; a bearing
which supports the screw rotor; a motor which drives the screw
rotor; a motor casing which accommodates the motor; a main casing
which accommodates the screw rotor; and a steel pipe chamber which
accommodates the motor casing and the main casing, wherein the
steel pipe chamber is able to be divided in the axial direction,
and wherein a space inside the steel pipe chamber which is able to
be divided is divided into a low-pressure-side space and a
high-pressure-side space through a sealing component.
[0019] According to the invention, since the steel pipe chamber
accommodating the motor casing and the main casing is provided, the
steel pipe chamber is able to be divided in the axial direction,
and the space inside the steel pipe chamber which is able to be
divided is divided into the low-pressure-side space and the
high-pressure-side space through the sealing component, it is
possible to obtain a screw compressor which is small in size and
weight and has ease of maintenance and high reliability.
[0020] Other objects, features and advantages of the invention will
become apparent from the following description of the embodiments
of the invention taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0021] FIG. 1 is a vertical sectional view of a screw compressor
according to a first embodiment of the invention.
[0022] FIG. 2 is a vertical sectional view of a screw compressor
according to a second embodiment of the invention.
[0023] FIG. 3 is a vertical sectional view of a screw compressor
according to a third embodiment of the invention.
[0024] FIG. 4 is a vertical sectional view of a screw compressor
according to a fourth embodiment of the invention.
[0025] FIG. 5 is a vertical sectional view of a screw compressor
according to a fifth embodiment of the invention.
[0026] FIG. 6 is a plan sectional view of a screw compressor
according to a sixth embodiment of the invention.
[0027] FIG. 7 is a plan sectional view of a screw compressor
according to a seventh embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0028] Hereinafter, the specific embodiments of the invention will
be described by referring to the drawings. In the respective
drawings, the same reference numerals are given to the same and
equivalent constituents.
First Embodiment
[0029] FIG. 1 shows a first embodiment according to the invention.
In the following description, although a twin screw compressor
having two male and female screw rotors are exemplified as the
embodiment, the invention is not limited to the twin screw
compressor, but may be also applied to a single screw compressor
having one screw rotor.
[0030] As shown in FIG. 1, a screw compressor includes a motor
casing 1, a main casing 2, and a discharge casing 3 which are
connected to each other. The motor casing 1 accommodates a driving
motor 4 which drives a compression mechanism portion, and is fixed
to the main casing 2 through means such as bolts. The main casing 2
is provided with a cylindrical bore 5 and a suction port 6 which
introduces a refrigerant gas into the cylindrical bore 5. The
cylindrical bore 5 accommodates a female rotor (not shown) and a
male rotor 14, rotatably supported by roller bearings 7, 8, and 9
(the low-pressure-side bearings 7 and 8 and the high-pressure-side
bearing 9) and a ball bearing 12 (the high-pressure-side bearing),
so as to mesh the rotors with each other, and a shaft portion of
the male rotor 14 is directly connected to the motor 4. The
discharge casing 3 accommodates the roller bearing 9 and the ball
bearing 12 (the high-pressure-side bearings), and the bearings are
fixed to the main casing 2 through means such as bolts. In
addition, one end of the discharge casing 3 is attached with a
closure plate 17 which closes a bearing chamber 16 for
accommodating the roller bearing 9 and the ball bearing 12.
[0031] Oil feeding channels 18 and 19 are formed inside the main
casing 2 and the discharge casing 3 so as to allow an oil storage
tank 20 provided in the lower portions of high-pressure-side
chambers 22 and 23 to communicate with the above-described
bearings.
[0032] The motor casing 1, the main casing 2, and the discharge
casing 3 are accommodated in a steel pipe chamber which is adapted
to be divided in the axial direction. The steel pipe chamber
includes a low-pressure-side chamber 21 and the high-pressure-side
chambers 22 and 23. When flanges 24, 25, 26, and 27 formed in
outer-surface ends of the chambers are connected to each other
through means such as bolts together with sealing components (not
shown), it is possible to seal the inside of the steel pipe chamber
from the ambient air, and to obtain a structure in which the steel
pipe chamber is able to be divided in the axial direction. The
high-pressure-side chambers are formed to be divided into two parts
in the axial direction so as to include the first
high-pressure-side chamber 22 which is connected to the
low-pressure-side chamber and the second high-pressure-side chamber
23 which is connected to the first high-pressure-side chamber
22.
[0033] The flange 29 formed in the main casing 2 and the flange 28
formed inside the high-pressure-side chamber 22 are connected
through bolts with a sealing component 30 interposed therebetween.
Accordingly, spaces 31 and 32 inside the steel pipe chamber are
divided into the space 31 defined as a low-pressure-side space, and
the space 32 defined as a high-pressure-side space.
[0034] Next, the streams of the refrigerant gas and the oil will be
described.
[0035] The foreign materials in the low-temperature and
low-pressure refrigerant gas sucked from a suction port 33 provided
in the low-pressure-side chamber 21 are collected by a strainer 34,
and then, the refrigerant gas passes through a gas channel provided
between the motor 4 and the motor casing 1 and an air gap between a
stator 4a and a rotor 4b of the motor so as to cool the motor 4.
The refrigerant gas used for the cooling operation is sucked from a
suction port 6 formed in the main casing 2 to a suction chamber
formed by the main casing 2 and meshing tooth surfaces of the male
and female screw rotors. Subsequently, the refrigerant gas is
hermetically sealed in a compression chamber formed by the main
casing 2 and the meshing tooth surfaces of the male and female
screw rotors in accordance with the rotation of the male rotor 14
connected to the motor 4, and is gradually compressed in accordance
with the contraction of the compression chamber, so that the
refrigerant gas becomes a high-temperature and high-pressure gas.
The compressed refrigerant gas passes through a discharge channel
35 and a discharge pipe 36 formed in the discharge casing 3, and is
discharged toward an end cover 37 constituting the
high-pressure-side chamber 23.
[0036] During the compression operation, a radial load of a
compression reaction force acting on the male and female screw
rotors is supported by the roller bearings 7, 8, and 9, and a
thrust load thereof is supported by the ball bearing 12. By means
of a differential pressure, an oil used for cooling and lubricating
the bearings is fed from the oil storage tank 20 provided in the
lower portions of the high-pressure-side chambers 22 and 23 via the
oil feeding channels 18 and 19 communicating with each of the
bearings. The oil used for the oil feeding operation is discharged
to the end cover 37 constituting the high-pressure-side chamber 23
together with the compressed refrigerant gas. The oil contained in
the compressed refrigerant gas is first separated by the collision
with the end cover 37, is secondarily separated by a collection oil
separator such as a demister 38 installed in the high-pressure-side
chamber 23, and is collected in the oil storage tank 20 provided in
the lower portions of the high-pressure-side chambers 22 and 23.
The compressed refrigerant gas passes through a gas channel 39 of
the upper portion of the high-pressure-side chamber 22, and is
discharged through a discharge port 40 provided in the
high-pressure-side chamber 22.
[0037] In the screw compressor of the related art, the motor casing
1, the main casing 2, and the discharge casing 3 are connected to
each other so as to be sealed, and serve as a pressure-resistant
casing which maintains the internal pressure. Meanwhile, the screw
compressor is formed into a complex casing structure so as to
accommodate a volume control slide valve or a screw rotor having a
three-dimensionally twisted complex curved surface. For this
reason, generally, the casing of the screw compressor is made from
cast iron which is able to be formed in a complex shape. In the
case where the casing is made from cast iron, since the strength is
lower than that of steel for a pressure pipe, the thickness of the
casing needs to be increased in order to maintain the strength, and
hence there is a tendency that the mass of the compressor
increases. On the contrary, in the structure of the embodiment,
since the internal pressure is maintained by the steel pipe
chamber, the main casing 2 made from cast iron is mainly used to
accommodate the compression mechanism portion. Accordingly, it is
possible to minimize the mass of the cast iron, and to obtain a
screw compressor which is small in size and weight.
[0038] In addition, in the embodiment of FIG. 1, the central axis
of the shell constituting the steel pipe chamber is disposed in the
horizontal direction. In the case where the steel pipe chamber is
disposed in the horizontal direction, since the low center of
gravity is realized, it is possible to obtain excellent safety when
the compressor is carried in or out. However, the invention is not
limited to the case in which the steel pipe chamber is disposed in
the horizontal direction, but even when the central axis of the
shell constituting the steel pipe chamber is disposed in the
vertical direction, it is possible to minimize the mass of the cast
iron casing used for accommodating the compression mechanism
portion.
[0039] The screw compressor of the related art in which the cast
iron casing is accommodated in the steel pipe chamber has a
structure in which the pressure inside the steel pipe chamber is
set to the low pressure before compressing the refrigerant gas or
the high pressure after compressing the refrigerant gas or a
structure in which different types of metals, that is, the steel
pipe and the cast iron are welded to each other so as to form
divided high-pressure and low pressure chambers.
[0040] In the case where the inside of the steel pipe chamber is
set to the low pressure, since the refrigerant gas compressed by
the screw rotor needs to be immediately discharged to the outside
of the steel pipe chamber, it is difficult to install the oil
separator in the inside of the steel pipe chamber. For this reason,
it is necessary to separately install the oil separator, and it is
difficult to realize a compact in size.
[0041] In the case where the inside of the steel pipe chamber is
set to the high pressure, since the driving motor 4 is cooled by
the high-pressure and high-temperature refrigerant gas, and the
driving motor 4 is overheated during the operation of the
compressor, there is a problem in that the reliability is not
satisfactory. In addition, although an insulation member of the
driving motor 4 is made from a resin material, it is necessary to
increase the heat-resistant grade of the resin material.
[0042] In the case where different types of metals are welded to
each other so as to form divided high pressure chamber and low
pressure chamber, when the welding condition is not optimally set,
cracks occur in the welded portion between the different types of
metals due to the insufficient welding penetration, and the
high-pressure refrigerant gas leaks to the low pressure portion, so
that the performance thereof is degraded. In addition, in order to
form the high pressure chamber and the low pressure chamber which
are divided from each other, since it necessary to weld the entire
circumference of the steel pipe chamber, the weld length is long.
Particularly, the weld length becomes longer as the capacity of the
compressor increases. The high-pressure refrigerant gas leaks to
the low pressure portion, so that the danger thereof increases. For
this reason, this structure is not suitable for a large capacity
compressor.
[0043] On the contrary, in the structure of the embodiment, since
the inside of the steel pipe chamber is divided into the
high-pressure space and the low-pressure space through the sealing
component 30, it is possible to dispose the driving motor 4 in a
position on the low pressure side of the inside of the steel pipe
chamber, and to dispose the oil separator in a position on the high
pressure side of the inside of the steel pipe chamber. With such a
configuration, it is possible to cool the motor 4 using the
low-pressure and low-temperature refrigerant gas, and to dispose
the oil separator in the inside of the steel pipe chamber.
[0044] In the embodiment, as the oil separator, both the
collision-type oil separation using the end cover 37 and the
collection-type oil separation using the demister 38 are used. In
addition, since the low pressure portion and the high pressure
portion are divided by the sealing component 30, the airtightness
is excellent, and the possibility that the performance is degraded
due to the leakage of the high-pressure refrigerant gas to the low
pressure portion is extremely small. In addition, since it is
possible to divide the steel pipe chamber into the
low-pressure-side chamber 21 and the high-pressure-side chambers 22
and 23, it is possible to easily perform maintenance such as the
exchange of the bearing.
Second Embodiment
[0045] FIG. 2 shows a second embodiment according to the invention.
As in the embodiment of FIG. 1, the steel pipe chamber includes the
low-pressure-side chamber 21 and the high-pressure-side chambers 22
and 23. Since the flanges 24, 25, 26, and 27 formed in the chambers
are connected to each other through means such as bolts, the
low-pressure-side chamber 21 and the high-pressure-side chambers 22
and 23 are sealed from each other, are sealed from the ambient air,
and are able to be divided.
[0046] The embodiment is different from the first embodiment in
that the flange 29 formed in the motor casing 1 and the flange 28
formed inside the high-pressure-side chamber 22 are connected to
each other through bolts with the sealing component 30 interposed
therebetween. Even in the embodiment, the spaces 31 and 32 inside
the steel pipe chamber are divided into the space 31 as the
low-pressure-side space and the space 32 as the high-pressure-side
space. Additionally, it is possible to cool the driving motor 4 by
using the low-pressure and low-temperature refrigerant gas, and to
dispose the oil separator in the inside of the steel pipe chamber.
Further, it is possible to obtain the excellent airtightness
between the low pressure portion and the high pressure portion, and
to easily perform maintenance.
Third Embodiment
[0047] FIG. 3 shows a third embodiment according to the invention.
As in the embodiment of FIG. 1, the steel pipe chamber includes the
low-pressure-side chamber 21 and the high-pressure-side chamber 22.
In addition, the flanges 24 and 25 formed in the chambers are
connected to each other through means such as bolts so as to be
sealed from each other, and are able to be divided. In the
embodiment, the flange 29 formed in the main casing 2 and the
flange 28 formed in the inside of the low-pressure-side chamber 21
are connected to each other through bolts with the sealing
component 30 interposed therebetween. The spaces 31 and 32 inside
the steel pipe chamber is divided into the space 31 as the
low-pressure-side space and the space 32 as the high-pressure-side
space. Even in the embodiment, it is possible to cool the driving
motor 4 by using the low-pressure and low-temperature refrigerant
gas, and to dispose the oil separator in the inside of the steel
pipe chamber. Further, it is possible to obtain the excellent
airtightness between the low pressure portion and the high pressure
portion, and to easily perform maintenance.
[0048] In addition, in the embodiment, since it is possible to
disassemble and/or assemble the compressor without dividing the
high-pressure-side chamber 22, it is not necessary to provide the
sealing component or the flange used for connecting the
high-pressure-side chambers. Accordingly, there is an advantage in
that it is possible to obtain the compressor which is more
simplified and reliable compared with the embodiment in which the
high-pressure-side chamber 22 needs to be divided.
Fourth Embodiment
[0049] FIG. 4 shows a fourth embodiment according to the invention.
As in the embodiment of FIG. 1, the steel pipe chamber includes the
low-pressure-side chamber 21 and the high-pressure-side chamber 22.
In addition, the flanges 24 and 25 formed in the chambers are
connected to each other through means such as bolts so as to be
sealed from each other, and are able to be divided. The embodiment
is different from the above-described embodiments in that the
flange 29 formed in the motor casing 1 and the flange 28 formed in
the inside of the low-pressure-side chamber 21 are connected to
each other through bolts with the sealing component 30 interposed
therebetween. Even in the embodiment, the spaces 31 and 32 inside
the steel pipe chamber is divided into the space 31 as the
low-pressure-side space and the space 32 as the high-pressure-side
space. Accordingly, it is possible to cool the driving motor 4 by
using the low-pressure and low-temperature refrigerant gas, and to
dispose the oil separator in the inside of the steel pipe chamber.
Further, it is possible to obtain the excellent airtightness
between the low pressure portion and the high pressure portion, and
to easily perform maintenance. In addition, even in the embodiment,
as in the third embodiment, since it is possible to disassemble
and/or assemble the compressor without dividing the
high-pressure-side chamber 22, it is not necessary to provide the
sealing component between the high-pressure-side chambers required
when the high-pressure-side chamber 22 is divided.
Fifth Embodiment
[0050] FIG. 5 shows a fifth embodiment according to the invention.
As in the embodiment of FIG. 1, the steel pipe chamber includes the
low-pressure-side chamber 21 and the high-pressure-side chambers 22
and 23. Since the flanges 24, 25, 26, and 27 formed in the chambers
are connected to each other through means such as bolts, the steel
pipe chamber is able to be divided. In the embodiment, the flange
25 integrally formed with a shell 41 is disposed over both sides,
that is, an ambient air side 25a of the shell 41 and a refrigerant
side 25b thereof. In the embodiment, since it is not necessary to
further install a flange used for the connection to the casing in
the inside of the shell 41, it is possible to divide the inside of
the steel pipe chamber into the low-pressure-side space 31 and the
high-pressure-side space 32 in a more simplified structure.
[0051] In addition, in the embodiment, the flange 29 formed in the
main casing 2 and the flange 25 formed in the high-pressure-side
chamber 22 are connected to each other through bolts, but even in
the configuration in which the flange formed in the motor casing is
connected to the flange formed in the high-pressure-side chamber
through bolts, the flange formed in the main casing is connected to
the flange formed in the low-pressure-side chamber through bolts,
or the flange formed in the motor casing is connected to the flange
formed in the low-pressure-side chamber through bolts, it is
possible to obtain the same advantages.
Sixth Embodiment
[0052] FIG. 6 shows a sixth embodiment according to the invention.
As in the embodiment of FIG. 1, the motor casing 1, the main casing
2, and the discharge casing 3 are accommodated in the steel pipe
chamber which are adapted to be divided. The embodiment is
described as an example in which a refrigerant having a cooling
ability for each fluid per unit volume flow rate equal to or less
than 70% of a refrigerant R407C is used as an operation refrigerant
to be compressed. In the embodiment, the screw rotor accommodated
in the main casing 2 has a configuration in which the number of
teeth of the male rotor 14 is set to four, and the number of teeth
of the female rotor 15 is set to six, and the driving motor 4
directly connected to the shaft portion of the male rotor 14 is
driven by an inverter 43 through the power supply terminal 42. A
male rotor 14 is rotatably supported by roller bearings 7, 8 and 9,
and a ball bearing 12. A female rotor 15 is rotatably supported by
roller bearings 10 and 11, and a ball bearing 13.
[0053] As refrigerants used in an air conditioner or a
refrigerating machine, there are many kinds of refrigerants such as
R410A, R407C, R134a, ammonia, and carbon dioxide, and they have
different cooling abilities for each fluid per unit of volume. In
the case where it is assumed that the cooling ability required for
the air conditioner or the refrigerating machine is the same, when
a refrigerant having a large cooling ability per unit volume is
adopted, a theoretical discharge amount of the compressor becomes
small, and hence it is possible to make the compressor decrease in
size. On the contrary, when a refrigerant having a small cooling
ability per unit volume is adopted, the compressor increases in
size. For example, when the cooling ability per unit volume flow
rate of the refrigerant R407C is set to 100, the refrigerant R410A
is about 150, and the refrigerant R134a is about 65. Thus, in the
case of obtaining the same cooling ability, when the refrigerant
R134a is adopted, the compressor increases in size compared with
the case adopting the R407C or R410A. Recently, a refrigerant (a
low GWP refrigerant) having a low global warming potential has
gained attention. The refrigerant generally has a small cooling
ability per unit volume as in, for example, R134a. However,
according to the embodiment, even when the low GWP refrigerant is
used, it is possible to realize a decrease in weight of the
compressor.
[0054] As the number of teeth of the male rotor 14 and the female
rotor 15 of the screw compressor, there are a combination of five
and six and a combination of five and seven. However, in the case
where the diameter of the rotor is the same, since the area of the
tooth groove becomes large as the number of teeth becomes small,
there is a tendency that the theoretical discharge amount
increases. In the embodiment, even in the case where the
refrigerant having a small cooling ability per unit volume flow
rate is adopted, the number of teeth of the male rotor 14 and the
female rotor 15 is set to a combination of four and six, and the
driving motor 4 directly connected to the shaft portion of the male
rotor 14 is driven by the inverter 43 so as to be accelerated.
According to the embodiment, the compressor used with an external
power supply 44 and driven at a constant speed can be remarkably
decreased in size and weight.
Seventh Embodiment
[0055] FIG. 7 shows a seventh embodiment of the invention. As in
the embodiment of FIG. 1, the motor casing 1, the main casing 2,
and the discharge casing 3 are accommodated in the steel pipe
chamber which is able to be divided. A central axis 47 of the steel
pipe chamber is disposed between a central axis 45 of the male
rotor 14 and the driving motor 4 directly connected to the male
rotor 14, and a central axis 46 of the female rotor 15. In the twin
screw compressor, the central axis of the male rotor 14 and the
central axis of the female rotor 15 always exist. Since the central
axis of the steel pipe chamber is disposed between two axes, it is
possible to decrease a dead space inside the steel pipe chamber
generated when the cast iron casing is disposed inside the steel
pipe chamber, and thus to further decrease the size of the screw
compressor.
[0056] In addition, in the above-described embodiments, the twin
screw compressor is exemplified, but the invention may be also
applied to the single screw compressor. When the single screw
compressor is exemplified, the single screw compressor is provided
with a screw rotor which includes a toothed portion and a shaft
portion, a gate rotor which meshes with the screw rotor, a
low-pressure-side bearing and a high-pressure-side bearing which
support the shaft portion of the screw rotor, a bearing which
supports the shaft portion of the gate rotor, a motor which is
directly connected to the shaft portion of the screw rotor and
drives the screw rotor, a motor casing which accommodates the
motor, and a main casing which accommodates the screw rotor and the
gate rotor. Even in the case of the single screw compressor, the
steel pipe chamber accommodating the motor casing and the main
casing is provided, and the steel pipe chamber is divided in the
axial direction so as to form the low-pressure-side chamber and the
high-pressure-side chamber. In addition, when the space inside the
steel pipe chamber is divided into the low-pressure-side space and
the high-pressure-side space through the flange provided in the
inner surface of the steel pipe chamber, the flange provided in the
main casing or the motor casing, and the sealing component provided
between the flanges, it is possible to obtain the same advantages
as those of the above-described embodiments.
[0057] Further, in the above-described embodiments, the example is
described in which the flange provided in the inner surface of the
shell 41 and the flange provided in the main casing or the motor
casing are connected to each other through the sealing component
30, that is, the flange is disposed on both the ambient air side
and the refrigerant side of the shell. However, instead of forming
the flange in the inner surface of the shell, even when the flange
provided in the main casing or the motor casing is fitted to the
flange provided in the outer-surface ends of the low-pressure-side
chamber and the high-pressure-side chamber together with the
sealing component, it is possible to divide the inside of the steel
pipe chamber into the low-pressure-side space 31 and the
high-pressure-side space 32. According to the embodiment, it is not
necessary to provide the flange of the inner surface of the shell,
and thus to more simplify the structure.
[0058] According to the above-described embodiments, since the
compression mechanism portion is accommodated in the steel pipe
chamber, it is possible to remarkably decrease the size and weight
of the screw compressor. In addition, the steel pipe chamber is
adapted to be divided, and the space inside the steel pipe chamber
is adapted to be divided into the low pressure portion and the high
pressure portion through the sealing component. Accordingly, in the
invention, it is possible to dispose the motor on the low pressure
side and to dispose the oil separator on the high pressure side
after making the compressor in a semi-hermetic state, which is
difficult in the steel pipe chamber structure of the related art.
As a result, it is possible to obtain a screw compressor which is
small in size and weight and has ease of maintenance and high
reliability.
[0059] It should be further understood by those skilled in the art
that although the foregoing description has been made on
embodiments of the invention, the invention is not limited thereto
and various changes and modifications may be made without departing
from the spirit of the invention and the scope of the appended
claims.
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