U.S. patent application number 14/680442 was filed with the patent office on 2015-10-22 for turbomachine and refrigeration cycle apparatus.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to AKIRA HIWATA, KAZUYUKI KOUDA, MAMORU NISHIBU, TADAYOSHI SHOYAMA, HIDETOSHI TAGUCHI.
Application Number | 20150300697 14/680442 |
Document ID | / |
Family ID | 53442447 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150300697 |
Kind Code |
A1 |
NISHIBU; MAMORU ; et
al. |
October 22, 2015 |
TURBOMACHINE AND REFRIGERATION CYCLE APPARATUS
Abstract
A turbomachine for a refrigeration cycle apparatus that uses a
refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature includes a rotation shaft and a bearing for
supporting the rotation shaft. The rotation shaft includes a
lubricant supply passage for supplying the refrigerant as a
lubricant that travels smoothly between the rotation shaft and the
bearing. The lubricant supply passage includes a main passage and a
sub-passage. The main passage extends from an inlet located at an
end of the rotation shaft in an axial direction of the rotation
shaft. The sub-passage diverges from the main passage and extends
to an outlet located in a side surface of the rotation shaft.
Inventors: |
NISHIBU; MAMORU; (Osaka,
JP) ; TAGUCHI; HIDETOSHI; (Osaka, JP) ;
HIWATA; AKIRA; (Shiga, JP) ; SHOYAMA; TADAYOSHI;
(Osaka, JP) ; KOUDA; KAZUYUKI; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
53442447 |
Appl. No.: |
14/680442 |
Filed: |
April 7, 2015 |
Current U.S.
Class: |
415/115 ;
62/498 |
Current CPC
Class: |
F25B 11/04 20130101;
F25B 31/002 20130101; F25B 1/047 20130101; F04D 29/04 20130101;
F04D 29/047 20130101; F04D 29/056 20130101; F04D 29/053 20130101;
F04D 29/063 20130101; F25B 11/00 20130101; F25B 1/06 20130101; F16C
33/1055 20130101 |
International
Class: |
F25B 11/00 20060101
F25B011/00; F04D 29/056 20060101 F04D029/056; F04D 29/063 20060101
F04D029/063; F04D 29/053 20060101 F04D029/053 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2014 |
JP |
2014-086170 |
Claims
1. A turbomachine for a refrigeration cycle apparatus that uses a
refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature, the turbomachine comprising: a rotation
shaft; and a bearing that supports the rotation shaft, wherein the
rotation shaft includes a lubricant supply passage containing a
main passage that extends from an inlet located at an end of the
rotation shaft in an axial direction of the rotation shaft, and one
or more sub-passages that diverge from the main passage and that
extend to an outlet located in a side surface of the rotation
shaft, and while the rotation shaft rotates, the lubricant supply
passage supplies the refrigerant to a portion where is located
between the rotation shaft and the bearing.
2. The turbomachine according to claim 1, wherein the sub-passage
intersects a central axis of the main passage and extends along a
straight line perpendicular to the central axis.
3. The turbomachine according to claim 1, wherein the outlet of the
sub-passage is located at a more backward position in a direction
of rotation of the rotation shaft than a point at which a straight
line intersects the side surface of the rotation shaft, the
straight line connecting a central axis of the main passage and a
center of an opening of the sub-passage on a side of the main
passage.
4. The turbomachine according to claim 1, wherein when the
sub-passage is viewed in an axial direction of the rotation shaft,
the sub-passage is expanded backward in a direction of rotation of
the rotation shaft from a position in the sub-passage to the
outlet, the position being located between an opening of the
sub-passage on a side of the main passage and the outlet.
5. The turbomachine according to claim 1, wherein the lubricant
supply passage includes the plurality of sub-passages arranged in
the axial direction of the rotation shaft.
6. The turbomachine according to claim 1, wherein when the
sub-passage is viewed from a direction perpendicular to the axial
direction of the rotation shaft, a central axis of the sub-passage
is tilted with respect to a central axis of the main passage in the
axial direction of the rotation shaft.
7. The turbomachine according to claim 1, further comprising: a
storage portion that adjoins the bearing on a side of the inlet and
stores the refrigerant as the lubricant, wherein the inlet located
at the end of the rotation shaft is soaked in the refrigerant
stored in the storage portion as the lubricant.
8. A refrigeration cycle apparatus comprising: a main circuit that
circulates a refrigerant whose saturated vapor pressure is a
negative pressure at ordinary temperature, the main circuit
including an evaporation mechanism that stores a refrigerant liquid
and evaporates the refrigerant liquid, an turbomachine according to
claim 1, and a condensation mechanism that condenses refrigerant
vapor and stores a refrigerant liquid, the evaporation mechanism,
the turbomachine, and the condensation mechanism being connected in
named order; an evaporation-side circulation circuit that includes
a heat-absorption-side liquid carrying pump and a heat-absorption
heat exchanger, the heat-absorption-side liquid carrying pump
causing the refrigerant liquid stored in the evaporation mechanism
to be supplied to the heat-absorption heat exchanger, the
refrigerant after heat absorption in the heat-absorption heat
exchanger being returned to the evaporation mechanism; a
condensation-side circulation circuit that includes a
heat-radiation-side liquid carrying pump and a heat-radiation heat
exchanger, the heat-radiation-side liquid carrying pump causing the
refrigerant liquid stored in the condensation mechanism to be
supplied to the heat-radiation heat exchanger, the refrigerant
after heat radiation in the heat-radiation heat exchanger being
returned to the condensation mechanism; and an upstream-side supply
passage that diverges from the evaporation-side circulation circuit
at a position downstream of an exit of the heat-absorption-side
liquid carrying pump in the evaporation-side circulation circuit or
diverges from the condensation-side circulation circuit at a
position downstream of an exit of the heat-radiation-side liquid
carrying pump in the condensation-side circulation circuit, and
supplies the refrigerant to the lubricant supply passage.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to a turbomachine and
particularly relates to a turbomachine for a refrigeration cycle
apparatus that uses a refrigerant whose saturated vapor pressure is
a negative pressure at ordinary temperature specified as 20.degree.
C..+-.15.degree. C. in JIS Z8703 of Japanese Industrial Standards
(JIS), which is pressure lower than atmospheric pressure when
measured as absolute pressure.
[0003] 2. Description of the Related Art
[0004] Conventionally, refrigeration cycle apparatuses that use
chlorofluorocarbon (CFC) refrigerants or alternative CFC
refrigerants have been widely used. However, such refrigerants
cause problems including destruction of the ozone layer and global
warming. Thus, refrigeration cycle apparatuses that use water as
refrigerants capable of greatly reducing loads to the global
environment are proposed.
[0005] For example, as illustrated in FIG. 12, International
Publication No. 2010/010925 describes a refrigerator 300 that
includes a compressor 301, an evaporator 302, a condenser 304, a
cooling tower 316, and a cooling water pump 318. In the
refrigerator 300, water is used as a refrigerant. The compressor
301 includes a rotation shaft 310, an impeller 312, and a bearing
320. In the compressor 301, water is supplied to the bearing 320 as
a lubricant. Specifically, the discharge pressure of the cooling
water pump 318 is utilized to carry part of the cooling water
supplied to the condenser 304 to the bearing 320. The refrigerator
described in International Publication No. 2010/010925 is
susceptible of increasing reliability of the compressor.
SUMMARY
[0006] One non-limiting and exemplary embodiment provides a highly
reliable turbomachine for a refrigeration cycle apparatus that uses
a refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature.
[0007] In one general aspect, the techniques disclosed here feature
a turbomachine for a refrigeration cycle apparatus that uses a
refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature, the turbomachine including a rotation
shaft and a bearing for supporting the rotation shaft, where the
rotation shaft includes a lubricant supply passage that includes a
main passage extending from an inlet located at an end of the
rotation shaft in an axial direction of the rotation shaft, and one
of more sub-passage that divere from the main passage and that
extend to an outlet located in a side surface of the rotation
shaft, and the lubricant supply passage supplies the refrigerant to
a portion between the rotation shaft and the bearing.
[0008] Additional benefits and advantages of the disclosed
embodiments will become apparent from the specification and
drawings. The benefits and/or advantages may be individually
obtained by the various embodiments and features of the
specification and drawings, which need not all be provided in order
to obtain one or more of such benefits and/or advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a cross-sectional diagram of a turbomachine
according to a first embodiment;
[0010] FIG. 2 is a cross-sectional diagram of a rotation shaft
along line II-II in FIG. 1;
[0011] FIG. 3 is a cross-sectional diagram of a rotation shaft
according to a variation;
[0012] FIG. 4 is a cross-sectional diagram of a rotation shaft
according to another variation;
[0013] FIG. 5 is a cross-sectional diagram of a rotation shaft and
a bearing according to still another variation;
[0014] FIG. 6 is a cross-sectional diagram of a rotation shaft
along line VI-VI in FIG. 5;
[0015] FIG. 7 is a cross-sectional diagram of a rotation shaft and
a bearing according to still another variation;
[0016] FIG. 8 is a cross-sectional diagram of a rotation shaft and
a bearing according to still another variation;
[0017] FIG. 9 is a configuration diagram illustrating an example of
a refrigeration cycle apparatus that includes the turbomachine in
FIG. 1;
[0018] FIG. 10 is a configuration diagram illustrating another
example of a refrigeration cycle apparatus that includes the
turbomachine in FIG. 1;
[0019] FIG. 11 is a cross-sectional diagram illustrating a
condensation mechanism according to a variation; and
[0020] FIG. 12 is a configuration diagram illustrating a
conventional refrigerator.
DETAILED DESCRIPTION
[Underlying Knowledge Forming Basis of the Present Disclosure]
[0021] The present inventors have conducted study of a turbomachine
referred to as the "turbomachine in the study stage" hereinafter,
which is a turbomachine for a refrigeration cycle apparatus that
uses a refrigerant whose saturated vapor pressure is a negative
pressure at ordinary temperature specified as 20.degree.
C..+-.15.degree. C. in JIS Z8703, which is pressure lower than
atmospheric pressure when measured as absolute pressure. The
turbomachine in the study stage includes a rotation shaft and a
bearing that supports the rotation shaft, and includes a lubricant
supply passage that supplies a refrigerant as a lubricant that
travels smoothly between the rotation shaft and the bearing. As a
result, the knowledge described below has been obtained.
[0022] In the turbomachine in the study stage, what is supplied to
the bearing as the lubricant is not a "lubricating oil" but
"water", which is the refrigerant. Thus, the turbomachine in the
study stage has been favorable in the points described below. That
is, when a "lubricating oil" is supplied to the bearing as the
lubricant, the lubricating oil and the water are mixed and cause a
suspension, and the performance of the lubrication considerably
decreases. As another possibility, when the suspension flows out
into the refrigeration cycle apparatus, the lubricating oil acts as
thermal resistance and reduces the performance of the refrigeration
cycle apparatus. In contrast, in the turbomachine in the study
stage, "water", which is the refrigerant, is supplied to the
bearing as the lubricant. Accordingly, the above-mentioned problems
caused by the suspension of the lubricating oil and the water may
be prevented and the considerable decrease in the performance of
the lubrication may be suppressed. In addition, the lubricant of
the bearing may be disposed of more easily and the configurations
of the turbomachine and the refrigeration cycle apparatus may be
simplified.
[0023] However, the present inventors have found that the
reliability of the turbomachine in the study stage is insufficient.
The reasons are given as follows. In the refrigeration cycle
apparatus that uses a refrigerant whose saturated vapor pressure is
a negative pressure at ordinary temperature, the pressure inside
the compressor is close to the saturated vapor pressure of the
refrigerant. Thus, when the refrigerant of the refrigeration cycle
apparatus is supplied to the bearing of the compressor as the
lubricant, the refrigerant is already in a state in which the
refrigerant easily evaporates. In particular, as regards slide
bearings used in turbomachines, the peripheral speed of the
rotation shaft of the turbomachine is high and the calorific amount
is large. As the peripheral speed of the rotation shaft of the
turbomachine increases, the pressure of the lubricant in a portion
in which the gap between the supported surface of the rotation
shaft and the slide surface of the bearing widens becomes a
negative pressure more easily. Accordingly, as the number of
rotations of the rotation shaft increases, cavitation is more
likely to occur in the refrigerant supplied as the lubricant. As a
result, the amount of the lubricant of the bearing is insufficient
and the reliability of the compressor is decreased.
[0024] Thus, the present inventors have considered applying
sufficiently high static pressure to the refrigerant supplied to
the bearing as the lubricant so as to suppress the evaporation of
the refrigerant and the occurrence of the cavitation in the
bearing. For example, utilization of the discharge pressure of the
cooling water pump has been considered so as to supply water to the
lubricant supply passage as the lubricant. It has been found
however that arranging a cooling water pump with high performance
is necessary so as to apply sufficiently high static pressure to
the refrigerant supplied to the bearing as the lubricant and that
the cost of the turbomachine increases accordingly.
[0025] Then, after careful review, the present inventors have
focused on the point that when a refrigerant whose saturated vapor
pressure is a negative pressure at ordinary temperature, such as
water, is used as an operating fluid, the turbomachine needs the
number of rotations that is very large as the number of rotations
of a rotation body. That is, it is desired that the turbomachine in
a refrigeration cycle apparatus that uses a refrigerant whose
saturated vapor pressure is a negative pressure at ordinary
temperature as an operating fluid achieve the higher pressure ratio
than the pressure ratio of the turbomachine in a refrigeration
cycle apparatus that uses a refrigerant whose saturated vapor
pressure is a positive pressure at ordinary temperature as an
operating fluid. Thus, the turbomachine needs the number of
rotations very large as the number of rotations of a rotation body.
The present inventors have reached the idea that if the centrifugal
force produced through the very large number of rotations is
utilizable to apply pressure to the refrigerant, it may be possible
to apply sufficiently high static pressure to the refrigerant
supplied to the bearing as the lubricant without using a cooling
water pump with high performance. On the basis of the
aforementioned knowledge, the present inventors have conceived the
present disclosure including the aspects described below.
[0026] A turbomachine according to a first aspect of the present
disclosure is a turbomachine for a refrigeration cycle apparatus
that uses a refrigerant whose saturated vapor pressure is a
negative pressure at ordinary temperature, the turbomachine
including a rotation shaft and a bearing that supports the rotation
shaft, where the rotation shaft includes a lubricant supply passage
therein, the lubricant supply passage including a main passage that
extends from an inlet located at an end of the rotation shaft in an
axial direction of the rotation shaft, and one or more sub-passages
that diverge from the main passage and that extend to an outlet
located in a side surface of the rotation shaft, and while the
rotation shaft rotates, the lubricant supply passage supplies the
refrigerant to a portion where is located between the rotation
shaft and the bearing.
[0027] According to the first aspect, with the rotation of the
rotation shaft, the refrigerant as the lubricant is supplied to the
bearing under pressure through the lubricant supply passage.
Accordingly, the pressure of the refrigerant supplied as the
lubricant increases and the evaporation of the refrigerant as the
lubricant or the occurrence of the cavitation may be suppressed in
the bearing. The turbomachine according to the first aspect is
oriented toward a refrigeration cycle apparatus that uses a
refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature, and includes the lubricant supply passage
for supplying the refrigerant as the lubricant that travels
smoothly between the rotation shaft and the bearing. As described
above, when the refrigerant whose saturated vapor pressure is a
negative pressure at ordinary temperature is used as an operating
fluid, the turbomachine needs the number of rotations that is very
large as the number of rotations of a rotation body. Thus,
according to the first aspect, since the centrifugal force produced
through the large number of rotations may be utilized to apply
pressure to the refrigerant, high pressure may be applied to the
lubricant supplied to the bearing through the lubricant supply
passage. Accordingly, shortage of the lubricant in the bearing may
be prevented and the reliability of the turbomachine may increase.
In addition, the performance that an external pump of the
turbomachine for supplying the refrigerant as the lubricant to the
lubricant supply passage is desired to offer may be reduced and
accordingly, the external pump may be downsized or the cost of the
refrigeration cycle apparatus may be lowered.
[0028] For example, when water is used in a refrigerator with a
refrigerating ability of a 10 kW class as an operating fluid, the
number of rotations of the rotation body in the turbomachine is
very large, which is in a range from approximately 75 thousand to
90 thousand rpm. In this case, depending on the design, the
pressure of the refrigerant liquid supplied between the rotation
shaft and the bearing is in a range from approximately 0.5 to 1
MPaA. In contrast, when the turbomachine according to the first
aspect is not used, that is, for example, the turbomachine in the
study stage, in which the rotation shaft has no lubricant supply
passage, is used, the discharge pressure of the external pump of
the turbomachine is desired to be in a range from approximately 200
to 400 KPaA so as to suppress the evaporation of the refrigerant
and the occurrence of cavitation in the bearing. In contrast, the
discharge pressure of the external pump of the turbomachine
according to the first aspect is in a range from approximately 50
to 80 KPaA. As described above, according to the first aspect, the
performance that the external pump of the turbomachine is desired
to offer may be reduced and accordingly, the external pump may be
downsized or the cost of the refrigeration cycle apparatus may be
lowered.
[0029] The first aspect of the present disclosure is favorable,
compared with the refrigerator 300 disclosed in International
Publication No. 2010/010925 in the points described below.
[0030] For example, in the refrigerator 300, the discharge pressure
of the cooling water pump 318 is utilized to carry water as the
lubricant to the bearing 320 and the reliability of the compressor
301 depends on the performance of the cooling water pump 318.
Depending on the performance of the cooling water pump 318, the
pressure of the water supplied to the bearing 320 as the lubricant
may be insufficient. In this case, the evaporation of the lubricant
or the cavitation in the lubricant may occur and cause shortage of
the amount of the lubricant in the bearing 320 and the reliability
of the compressor 301 may be decreased accordingly. Since the
cooling water pump 318 is desired to offer high performance so as
to increase the reliability of the compressor 301, the cooling
water pump 318 involves the high cost.
[0031] In contrast, the turbomachine according to the present
disclosure includes the lubricant supply passage that includes the
main passage extending from the inlet located at an end of the
rotation shaft in the axial direction of the rotation shaft, and
the sub-passage diverging from the main passage and extending to
the outlet located in the side surface of the rotation shaft, and
supplies the refrigerant as the lubricant traveling smoothly
between the rotation shaft and the bearing. Thus, the centrifugal
force produced through the rotation of the rotation shaft enables
pressure to be applied to the refrigerant in the lubricant supply
passage and accordingly, the refrigerant to which pressure is
applied may be supplied between the rotation shaft and the bearing.
That is, since the lubricant supply passage functions as a pump
mechanism that utilizes the rotation of the rotation shaft, the
occurrence of cavitation may be suppressed without using a cooling
water pump that has high performance.
[0032] In a second aspect of the present disclosure, the
sub-passage of the turbomachine according to the first aspect may
intersect a central axis of the main passage and extend along a
straight line perpendicular to the central axis. According to the
second aspect, the rotation shaft may be processed easily in
forming the sub-passage.
[0033] In a third aspect of the present disclosure, the outlet of
the sub-passage of the turbomachine according to the first aspect
may be located at a more backward position in a direction of
rotation of the rotation shaft than a point at which a straight
line intersects the side surface of the rotation shaft, the
straight line connecting a central axis of the main passage and a
center of an opening of the sub-passage on a side of the main
passage. According to the third aspect, decrease in the pressure of
the refrigerant as the lubricant is small while the refrigerant as
the lubricant flows through the lubricant supply passage and
cavitation is unlikely to occur in the flow of the refrigerant
through the lubricant supply passage.
[0034] In a fourth aspect of the present disclosure, when viewed in
an axial direction of the rotation shaft, the sub-passage of the
turbomachine according to the first aspect or the third aspect may
be expanded backward in the direction of rotation of the rotation
shaft from a position in the sub-passage to the outlet, the
position being located between an opening of the sub-passage on the
side of the main passage and the outlet. According to the fourth
aspect, decrease in the pressure of the refrigerant as the
lubricant is small while the refrigerant as the lubricant flows
through the lubricant supply passage and cavitation is unlikely to
occur in the flow of the refrigerant through the lubricant supply
passage
[0035] In a fifth aspect of the present disclosure, the lubricant
supply passage of the turbomachine according to any one of the
first to fourth aspects may include the plurality of sub-passages
arranged in the axial direction of the rotation shaft. According to
the fifth aspect, the amount of the refrigerant as the lubricant
supplied to the bearing through the lubricant supply passage
increases. Thus, the cooling ability of the bearing may be
enhanced.
[0036] In a sixth aspect of the present disclosure, when the
sub-passage is viewed from the direction perpendicular to the axial
direction of the rotation shaft, a central axis of the sub-passage
of the turbomachine according to any one of the first to fifth
aspects may be tilted with respect to the central axis of the main
passage in the axial direction of the rotation shaft. According to
the sixth aspect, the outlet may be located at a position where the
lubricant may be supplied suitably to the bearing while enhancing
the performance to cool the rotation shaft by forming the main
passage as long as possible. Occasionally, the outlet may be
located at a position where the lubricant may be supplied suitably
to the bearing while simplifying the processing of the rotation
shaft by forming the main passage as short as possible.
[0037] In a seventh aspect of the present disclosure, the
turbomachine according to any one of the first to sixth aspects may
further include a storage portion that adjoins the bearing on the
side of the inlet and stores the refrigerant as the lubricant,
where the inlet located at the end of the rotation shaft may be
soaked in the refrigerant stored in the storage portion as the
lubricant. According to the seventh aspect, the bearing and the
rotation shaft may be cooled by the lubricant stored in the storage
portion.
[0038] A refrigeration cycle apparatus according to an eighth
aspect of the present disclosure includes: a main circuit that
circulates a refrigerant whose saturated vapor pressure is a
negative pressure at ordinary temperature, the main circuit
including an evaporation mechanism that stores a refrigerant liquid
and evaporates the refrigerant liquid, the turbomachine according
to any one of the first to seventh aspects that is a compressor
that compresses refrigerant vapor, and a condensation mechanism
that condenses refrigerant vapor and stores a refrigerant liquid,
the evaporation mechanism, the turbomachine, and the condensation
mechanism being connected in named order; an evaporation-side
circulation circuit that includes a heat-absorption-side liquid
carrying pump and a heat-absorption heat exchanger, the
heat-absorption-side liquid carrying pump causing the refrigerant
liquid stored in the evaporation mechanism to be supplied to the
heat-absorption heat exchanger, the refrigerant after heat
absorption in the heat-absorption heat exchanger being returned to
the evaporation mechanism; a condensation-side circulation circuit
that includes a heat-radiation-side liquid carrying pump and a
heat-radiation heat exchanger, the heat-radiation-side liquid
carrying pump causing the refrigerant liquid stored in the
condensation mechanism to be supplied to the heat-radiation heat
exchanger, the refrigerant after heat radiation in the
heat-radiation heat exchanger being returned to the condensation
mechanism; and an upstream-side supply passage that diverges from
the evaporation-side circulation circuit at a position downstream
of an exit of the heat-absorption-side liquid carrying pump in the
evaporation-side circulation circuit or diverges from the
condensation-side circulation circuit at a position downstream of
an exit of the heat-radiation-side liquid carrying pump in the
condensation-side circulation circuit, and supplies the refrigerant
to the lubricant supply passage.
[0039] According to the eighth aspect, since the refrigerant to
which pressure is applied through the heat-absorption-side liquid
carrying pump or the heat-radiation-side liquid carrying pump is
supplied to the lubricant supply passage through the upstream-side
supply passage, the pressure of the refrigerant as the lubricant
supplied to the bearing may be further raised.
[0040] Embodiments of the present disclosure are described below
with reference to the drawings. The description below relates to
examples of the present disclosure and the present disclosure is
not limited by the examples.
<Turbomachine>
[0041] As illustrated in FIG. 1, a turbomachine 1a includes a
rotation shaft 10a and a bearing 20. The turbomachine 1a is a
turbomachine for a refrigeration cycle apparatus that uses a
refrigerant whose saturated vapor pressure is a negative pressure
at ordinary temperature. The turbomachine 1a is typically a
turbocompressor. The turbomachine 1a is configured as a fluid
machine of, for example, a centrifugal type, an axial-flow type, or
a diagonal-flow type. The bearing 20 is a bearing for supporting
the rotation shaft 10a and is, for example, a slide bearing that
supports the radial load of the rotation shaft 10a. An impeller 12
is attached to the rotation shaft 10a. The rotation shaft 10a is
connected to a motor, which is not illustrated. When the motor is
driven, the rotation shaft 10a and the impeller 12 rotate. Thus,
the refrigerant of the refrigeration cycle apparatus is sucked into
the turbomachine 1a and discharged from the turbomachine 1a after
being compressed. The refrigerant is not limited in particular as
long as the saturated vapor pressure of the refrigerant is a
negative pressure at ordinary temperature, and examples of the
refrigerant include a refrigerant that contains mainly water,
alcohol, or ether. The turbomachine 1a is operated at pressure near
the saturated vapor pressure of the refrigerant of the
refrigeration cycle apparatus. The pressure at the entrance of the
turbomachine 1a is in a range from, for example, 0.5 to 5 kPaA. The
pressure at the exit of the turbomachine 1a is in a range from, for
example, 5 to 15 kPaA.
[0042] The rotation shaft 10a includes a lubricant supply passage
30. The lubricant supply passage 30 is a passage for supplying the
refrigerant of the refrigeration cycle apparatus as the lubricant
that travels smoothly between the rotation shaft 10a and the
bearing 20. During the operation of the refrigeration cycle
apparatus, the lubricant supply passage 30 is filled with the
refrigerant of the refrigeration cycle apparatus liquid. The
lubricant supply passage 30 includes a main passage 31 and a
sub-passage 32. As illustrated in FIG. 1, the main passage 31
extends from an inlet 33 located at an end 11 of the rotation shaft
10a in the axial direction of the rotation shaft 10a. The
sub-passages 32 diverge from the main passage 31 and extend to
outlets 35 located in the side surface of the rotation shaft 10a.
As illustrated in FIG. 1, the sub-passage 32 is located so that the
outlet 35 faces the slide surface of the bearing 20. In FIG. 2,
although the lubricant supply passage 30 includes four sub-passages
as the sub-passages 32 positioned in the circumferential direction
of the rotation shaft 10a, the lubricant supply passage 30 may
include one sub-passage 32 or include two, three, five, or more
sub-passages 32 positioned in the circumferential direction of the
rotation shaft 10a.
[0043] During the operation of the turbomachine 1a, the rotation
shaft 10a rotates at high speed. The centrifugal force produced
through the rotation of the rotation shaft 10a causes the
refrigerant of the refrigeration cycle apparatus in the lubricant
supply passage 30 to be supplied between the rotation shaft 10a and
the bearing 20 while pressure is being applied to the refrigerant
of the refrigeration cycle apparatus in the lubricant supply
passage 30. Specifically, the refrigerant liquid of the
refrigeration cycle apparatus that flows into the main passage 31
from the inlet 33 flows through the main passage 31 in the axial
direction. After that, the refrigerant liquid is guided to the
sub-passage 32 and flows through the sub-passage 32 and out from
the outlet 35. The refrigerant liquid supplied between the rotation
shaft 10a and the bearing 20 travels smoothly between the rotation
shaft 10a and the bearing 20. In this manner, the lubricant supply
passage 30 functions as a pump mechanism that utilizes the rotation
of the rotation shaft 10a and the refrigerant liquid as the
lubricant is supplied between the rotation shaft 10a and the
bearing 20 at predetermined pressure. As described above, the
turbomachine 1a is operated at pressure near the saturated vapor
pressure of the refrigerant of the refrigeration cycle apparatus.
Since the lubricant supply passage 30 functions as a pump mechanism
that utilizes the rotation of the rotation shaft 10a, the pressure
of the refrigerant liquid supplied between the rotation shaft 10a
and the bearing 20 is high. The evaporation of the refrigerant
liquid supplied between the rotation shaft 10a and the bearing 20
as the lubricant or the occurrence of cavitation in the lubricant
may be suppressed accordingly. In addition, as the number of
rotations of the rotation shaft 10a increases, the pressure of the
lubricant supplied to the bearing 20 through the lubricant supply
passage 30 becomes higher. Thus, shortage of the lubricant in the
bearing 20 may be prevented and the turbomachine 1a has high
reliability.
[0044] As long as the rotation shaft 10a of the turbomachine 1a
rotates, the lubricant may be supplied to the bearing 20. For
example, even when power failure or the like stops the supply of
power to the motor that drives the rotation shaft 10a, not
illustrated, the lubricant may be supplied to the bearing 20 as
long as the rotation shaft 10a rotates and thus, the rotation shaft
10a may be stopped safely.
[0045] The turbomachine 1a includes a casing 50. A storage portion
40 is included in the casing 50. That is, the turbomachine 1a
further includes the storage portion 40. The storage portion 40 is
a space for storing the lubricant. The storage portion 40 stores
the lubricant. The storage portion 40 adjoins the bearing 20 on the
side of the inlet 33. The end 11 of the rotation shaft 10a is
soaked in the lubricant stored in the storage portion 40. The
casing 50 is provided with a supply hole 41 and a discharge hole
42. The refrigerant in a specific location of the refrigeration
cycle apparatus is supplied to the storage portion 40 through the
supply hole 41 using, for example, an external pump of the
turbomachine 1a, and stored in the storage portion 40 as the
lubricant. The refrigerant is discharged from the storage portion
40 through the discharge hole 42 and is returned to the specific
location of the refrigeration cycle apparatus. The lubricant stored
in the storage portion 40 is continuously supplied to the bearing
20 through the lubricant supply passage 30 because of the rotation
of the rotation shaft 10a. Further, the lubricant stored in the
storage portion 40 cools the bearing 20 and the rotation shaft
10a.
[0046] As described above, the refrigeration cycle apparatus is
desirably provided with a pump outside the turbomachine 1a so as to
supply the refrigerant as the lubricant from a specific location of
the refrigeration cycle apparatus to the lubricant supply passage
30. In this case, it is desirable to set the discharge pressure of
the external pump so that the pressure of the refrigerant at the
inlet 33 is equal to or more than the saturated vapor pressure.
Thus, the occurrence of cavitation may be suppressed in the
lubricant supply passage 30 and shortage of the amount of the
lubricant to be supplied to the bearing 20 may be prevented. Since
the refrigerant as the lubricant is supplied between the rotation
shaft 10a and the bearing 20 at high pressure by passing through
the lubricant supply passage 30, the performance that the external
pump is desired to offer may be reduced. Thus, the external pump
may be downsized or the cost of the refrigeration cycle apparatus
may be lowered.
[0047] For example, when water is used in a refrigerator with a
refrigerating ability of a 10 kW class as an operating fluid, the
number of rotations of the rotation body in the turbomachine is
very large, which is in a range from approximately 75 thousand to
90 thousand rpm. In this case, depending on the design, the
pressure of the refrigerant liquid supplied between the rotation
shaft and the bearing is in a range from approximately 0.5 to 1
MPaA. In contrast, when the turbomachine according to the present
disclosure is not used, that is, for example, the turbomachine in
the study stage, in which the rotation shaft has no lubricant
supply passage, is used, the discharge pressure of the external
pump of the turbomachine is desired to be in a range from
approximately 200 to 400 KPaA so as to suppress the evaporation of
the refrigerant and the occurrence of cavitation in the bearing. In
contrast, the discharge pressure of the external pump of the
turbomachine according to the present embodiment is in a range from
approximately 50 to 80 KPaA. As described above, according to the
present embodiment, the performance that the external pump of the
turbomachine is desired to offer may be reduced and accordingly,
the external pump may be downsized or the cost of the refrigeration
cycle apparatus may be lowered.
[0048] As illustrated in FIG. 2, the sub-passage 32 is located so
that a distance between the center of an opening 34 of the
sub-passage 32 on the side of the main passage 31 and the center of
the outlet 35 is the shortest. The sub-passage 32 is located so as
to extend straight. The sub-passage 32 is located so that a
straight line that connects the center of the opening 34 of the
sub-passage 32 on the side of the main passage 31 and the center of
the outlet 35 passes through a specific point on the central axis
of the main passage 31 and is orthogonal to the central axis of the
main passage 31. Accordingly, the rotation shaft 10a may be
processed easily in forming the sub-passage 32.
[Variations]
[0049] The above-described turbomachine 1a may be changed in
various terms. Variations of the turbomachine 1a are described
below. The same reference alphanumeric characters are given to the
elements in the variations that are the same as or correspond to
the elements in the above-described turbomachine 1a, and the
detailed description of such elements is omitted.
[0050] The rotation shaft 10a of the turbomachine 1a may be changed
like a rotation shaft 10b illustrated in FIG. 3. In the rotation
shaft 10b, sub-passages 32 are located so that outlets 35 are
located in more backward positions in the direction of the rotation
of the rotation shaft 10b than a point A. The point A is a point at
which a straight line Q, which connects a central axis P of a main
passage 31 and a center 34c of an opening 34 of the sub-passage 32
on the side of the main passage 31 and is perpendicular to the
central axis P of the main passage 31 and a side surface of the
rotation shaft 10a intersect. In FIG. 3, the rotation shaft 10b
rotates clockwise during the operation of the turbomachine 1a.
There are possibilities that when the refrigerant flows from the
main passage 31 into the sub-passage 32, the pressure of the
refrigerant as the lubricant may decrease as the flow of the
refrigerant changes and cavitation may be caused in the flow of the
refrigerant through a lubricant supply passage 30. By forming the
sub-passage 32 in the rotation shaft 10b as described above, change
in the velocity of the flow of the refrigerant may be made small
and decrease in the pressure of the refrigerant as the lubricant
may be suppressed when the refrigerant flows from the main passage
31 into the sub-passage 32. Accordingly, cavitation is unlikely to
occur in the flow of the refrigerant through the lubricant supply
passage 30.
[0051] The rotation shaft 10a of the turbomachine 1a may be changed
like a rotation shaft 10c illustrated in FIG. 4. In the rotation
shaft 10c, sub-passages 32 are viewed from the side of an inlet 33
in the axial direction of the rotation shaft 10c. Each of the
sub-passages 32 bends backward in the direction in which the
rotation shaft 10c rotates from a position in the sub-passage 32 to
an outlet 35, and the position is located between an opening 34 of
the sub-passage 32 on the side of a main passage 31 and the outlet
35. In FIG. 4, the rotation shaft 10c rotates clockwise during the
operation of the turbomachine 1a. By forming the sub-passage 32 as
described above, change in the velocity of the flow of the
refrigerant may be made small and decrease in the pressure of the
refrigerant as the lubricant may be suppressed when the refrigerant
flows through the sub-passage 32. Accordingly, cavitation is
unlikely to occur in the flow of the refrigerant through a
lubricant supply passage 30. As illustrated in FIG. 4, the
sub-passage 32 is located so that the passage cross-sectional area
of the sub-passage 32 is enlarged from the position at which the
sub-passage 32 bends toward the outlet 35. Thus, the refrigerant as
the lubricant in the sub-passage 32 may flow out easily through the
outlet 35.
[0052] The rotation shaft 10a of the turbomachine 1a may be changed
like a rotation shaft 10d illustrated in FIGS. 5 and 6. As
illustrated in FIG. 5, in the rotation shaft 10d, a lubricant
supply passage 30 includes a plurality of sub-passages 32 arranged
in the axial direction of the rotation shaft 10d. Accordingly, the
amount of the refrigerant as the lubricant supplied to the bearing
20 through the lubricant supply passage 30 increases. In addition,
unevenness in the amount of the refrigerant supplied to the bearing
20 in the axial direction of the rotation shaft 10d may be
suppressed. In this case, as illustrated in FIGS. 5 and 6, the
lubricant supply passage 30 includes a plurality of sub-passage
groups (two in the example of FIGS. 5 and 6), each of which
includes the plurality of sub-passages 32 (four in the example of
FIGS. 5 and 6) arranged in the circumferential direction of the
rotation shaft 10d. The plurality of sub-passage groups are
arranged in the axial direction of the rotation shaft 10d. As
illustrated in FIG. 6, the sub-passages 32 that belong to one of
the sub-passage groups arranged in the axial direction of the
rotation shaft 10d are shifted in the circumferential direction of
the rotation shaft 10d from the positions of the sub-passages 32
that belong to another one of the sub-passage groups. Specifically,
the sub-passages 32 that belong to one of the sub-passage groups
arranged in the axial direction of the rotation shaft 10d are
shifted in the circumferential direction of the rotation shaft 10d
from the positions of the sub-passages 32 that belong to another
one of the sub-passage groups by approximately 45.degree.. As a
result, unevenness in the amount of the refrigerant supplied to the
bearing 20 in the circumferential direction of the rotation shaft
10d may be suppressed. In the rotation shaft 10d, the sub-passages
32 may be located as illustrated in FIG. 3 or 4.
[0053] The rotation shaft 10a of the turbomachine 1a may be changed
like a rotation shaft 10e illustrated in FIG. 7 or a rotation shaft
10f illustrated in FIG. 8. In the rotation shaft 10e or the
rotation shaft 10f, sub-passages 32 are located so that a central
axis L of the sub-passage 32 is tilted in the axial direction of
the rotation shaft 10e or the rotation shaft 10f with respect to a
central axis P of a main passage 31. The sub-passages 32 are
located so that in the axial direction of the rotation shaft 10e,
an outlet 35 is closer to an inlet 33 than an opening 34 of the
sub-passage 32 on the side of the main passage 31 is. By forming
the sub-passages 32 in this manner, the main passage 31 may be
located as long as possible and the performance of cooling the
rotation shaft 10e may be enhanced while the outlets 35 may be
located at positions desirable for supplying the lubricant to the
bearing 20. For example, the outlets 35 may be located near the
center of the bearing 20 in the axial direction of the rotation
shaft 10e.
[0054] In the axial direction of the rotation shaft 10f, the
sub-passages 32 are located so that an outlet 35 is farther away
from an inlet 33 than an opening 34 of the sub-passage 32 on the
side of the main passage 31 is. By forming the sub-passages 32 in
this manner, even when the main passage 31 is located as short as
possible and the processing of the rotation shaft 10f is
simplified, the outlets 35 may be located at positions desirable
for supplying the lubricant to the bearing 20. For example, the
outlets 35 may be located near the center of the bearing 20 in the
axial direction of the rotation shaft 10f.
<Refrigeration Cycle Apparatus>
[0055] A refrigeration cycle apparatus that includes the
above-described turbomachine 1a is described below.
[0056] As illustrated in FIG. 9, a refrigeration cycle apparatus
100a includes a main circuit 5, an evaporation-side circulation
circuit 6, a condensation-side circulation circuit 7, and an
upstream-side supply passage 91a. The main circuit 5 includes an
evaporation mechanism 2, the turbomachine 1a, and a condensation
mechanism 4. The evaporation mechanism 2 stores a refrigerant
liquid and evaporates the refrigerant liquid. The evaporation
mechanism 2 is made up of, for example, a container with heat
insulating properties and resistance to pressure. The turbomachine
1a is a compressor that compresses refrigerant vapor. The
condensation mechanism 4 condenses the refrigerant vapor and stores
the refrigerant liquid. The condensation mechanism 4 is made up of,
for example, a container with heat insulating properties and
resistance to pressure. The main circuit 5 is a circuit in which
the evaporation mechanism 2, the turbomachine 1a, and the
condensation mechanism 4 are connected in named order. The exit of
the evaporation mechanism 2 and the entrance of the turbomachine 1a
are connected through a passage 5a. The exit of the turbomachine 1a
and the entrance of the condensation mechanism 4 are connected
through a passage 5b. The exit of the condensation mechanism 4 and
the entrance of the evaporation mechanism 2 are connected through a
passage 5c. The main circuit 5 is filled with, for example, a
refrigerant that contains mainly water, alcohol, or ether, and kept
in a state of a negative pressure lower than atmospheric pressure.
The refrigeration cycle apparatus 100a is included in, for example,
air conditioning equipment for air cooling purpose.
[0057] The evaporation-side circulation circuit 6 includes a
heat-absorption-side liquid carrying pump 61 and a heat-absorption
heat exchanger 62. The evaporation-side circulation circuit 6 is
configured so that the refrigerant liquid stored in the evaporation
mechanism 2 is supplied to the heat-absorption heat exchanger 62
with the heat-absorption-side liquid carrying pump 61 and the
refrigerant after heat absorption in the heat-absorption heat
exchanger 62 is returned to the evaporation mechanism 2. In the
evaporation-side circulation circuit 6, the evaporation mechanism 2
and the entrance of the heat-absorption-side liquid carrying pump
61 are connected through a passage 6a. The exit of the
heat-absorption-side liquid carrying pump 61 and the entrance of
the heat-absorption heat exchanger 62 are connected through a
passage 6b. Further, the exit of the heat-absorption heat exchanger
62 and the evaporation mechanism 2 are connected through a passage
6c. The refrigerant liquid in the evaporation mechanism 2, which
has a temperature decreased as a result of the evaporation of the
refrigerant in the evaporation mechanism 2, is carried by the
heat-absorption-side liquid carrying pump 61 to the heat-absorption
heat exchanger 62 under pressure. The refrigerant liquid is heated
in the heat-absorption heat exchanger 62 and returned to the
evaporation mechanism 2. The passage 6c may be provided with a
pressure reducing mechanism for reducing the pressure of the
refrigerant after the heat absorption in the heat-absorption heat
exchanger 62. The heat-absorption heat exchanger 62 cools indoor
air through the heat absorption of the refrigerant in the
heat-absorption heat exchanger 62.
[0058] The condensation-side circulation circuit 7 includes a
heat-radiation-side liquid carrying pump 71 and a heat-radiation
heat exchanger 72. The condensation-side circulation circuit 7 is
configured so that the refrigerant liquid stored in the
condensation mechanism 4 is supplied to the heat-radiation heat
exchanger 72 with the heat-radiation-side liquid carrying pump 71
and the refrigerant after heat radiation in the heat-radiation heat
exchanger 72 is returned to the condensation mechanism 4. In the
condensation-side circulation circuit 7, the condensation mechanism
4 and the entrance of the heat-radiation-side liquid carrying pump
71 are connected through a passage 7a. The exit of the
heat-radiation-side liquid carrying pump 71 and the entrance of the
heat-radiation heat exchanger 72 are connected through a passage
7b. The exit of the heat-radiation heat exchanger 72 and the
condensation mechanism 4 are connected through a passage 7c. The
refrigerant cooled indirectly in the heat-radiation heat exchanger
72 is guided to the condensation mechanism 4 through the passage
7c. Thus, the refrigerant vapor compressed in the turbomachine 1a
is cooled and condensed. The refrigerant liquid that has a
temperature raised through the condensation in the condensation
mechanism 4 is carried to the heat-radiation heat exchanger 72 with
the heat-radiation-side liquid carrying pump 71 under pressure and
cooled indirectly in the heat-radiation heat exchanger 72, and then
returned to the condensation mechanism 4. In the heat-radiation
heat exchanger 72, the refrigerant radiates heat against outdoor
air.
[0059] The upstream-side supply passage 91a diverges from the
evaporation-side circulation circuit 6 at a position downstream of
the exit of the heat-absorption-side liquid carrying pump 61 in the
evaporation-side circulation circuit 6. The upstream-side supply
passage 91a is a passage for supplying the refrigerant to the
lubricant supply passage 30 of the turbomachine 1a. For example,
the upstream-side supply passage 91a diverges from the
evaporation-side circulation circuit 6 at a position between the
exit of the heat-absorption-side liquid carrying pump 61 and the
entrance of the heat-absorption heat exchanger 62 in the
evaporation-side circulation circuit 6. Further, the upstream-side
supply passage 91a is connected to the turbomachine 1a so as to
communicate with the lubricant supply passage 30. For example, the
refrigerant that travels through the upstream-side supply passage
91a passes through the supply hole 41 to be supplied to the storage
portion 40. As described above, the refrigerant to which pressure
has been applied with the heat-absorption-side liquid carrying pump
61 passes through the upstream-side supply passage 91a to be
supplied to the lubricant supply passage 30 as the lubricant. In
this case, the discharge pressure of the heat-absorption-side
liquid carrying pump 61 is desirably set so that the pressure of
the refrigerant at the inlet 33 of the lubricant supply passage 30
is equal to or more than the saturated vapor pressure. When the
upstream-side supply passage 91a diverges from the evaporation-side
circulation circuit 6 at a position between the exit of the
heat-absorption-side liquid carrying pump 61 and the entrance of
the heat-absorption heat exchanger 62 in the evaporation-side
circulation circuit 6, the refrigerant with a relatively low
temperature may be supplied to the lubricant supply passage 30.
Thus, the lubricant may enhance the ability of cooling the rotation
shaft 10a and the bearing 20.
[0060] The upstream-side supply passage 91a may diverge from the
evaporation-side circulation circuit 6 at a position between the
exit of the heat-absorption heat exchanger 62 in the
evaporation-side circulation circuit 6 and the evaporation
mechanism 2. Also in this case, part of the refrigerant of the
refrigeration cycle apparatus 100a may be supplied to the lubricant
supply passage 30 as the lubricant.
[0061] The refrigeration cycle apparatus 100a further includes a
return passage 92a. The return passage 92a is a passage for
returning the refrigerant supplied to the lubricant supply passage
30 through the upstream-side supply passage 91a to the main circuit
5. For example, the return passage 92a communicates with the
storage portion 40 via the discharge hole 42. Further, the return
passage 92a is connected to the evaporation mechanism 2. The
refrigerant stored in the storage portion 40 is guided to the
return passage 92a through the discharge hole 42 to flow through
the return passage 92a and is returned into the evaporation
mechanism 2. The return passage 92a may be connected to the
condensation mechanism 4 so as to return the refrigerant to the
condensation mechanism 4.
[0062] The refrigeration cycle apparatus 100a may be included in,
for example, air conditioning equipment where cooling and heating
modes are switchable. In this case, an indoor heat exchanger placed
indoors and an outdoor heat exchanger placed outdoors are connected
to the evaporation mechanism 2 and the condensation mechanism 4 via
a four-way valve. In the cooling mode, the indoor heat exchanger
functions as the heat-absorption heat exchanger 62 and the outdoor
heat exchanger functions as the heat-radiation heat exchanger 72.
In the heating mode, the indoor heat exchanger functions as the
heat-radiation heat exchanger 72 and the outdoor heat exchanger
functions as the heat-absorption heat exchanger 62. The
refrigeration cycle apparatus 100a may be included in, for example,
a chiller. For example, the heat-absorption heat exchanger 62 may
cool gas other than air or liquid through the heat absorption of
the refrigerant. For example, the heat-radiation heat exchanger 72
may heat gas other than air or liquid through the heat radiation of
the refrigerant. The heat-absorption heat exchanger 62 and the
heat-radiation heat exchanger 72 are not limited in particular as
long as the heat-absorption heat exchanger 62 and the
heat-radiation heat exchanger 72 are indirect heat exchangers.
[0063] The refrigeration cycle apparatus 100a may be changed like a
refrigeration cycle apparatus 100b illustrated in FIG. 10. The
refrigeration cycle apparatus 100b has a configuration the same as
the configuration of the refrigeration cycle apparatus 100a unless
otherwise described. The same reference alphanumeric characters are
given to the elements in the refrigeration cycle apparatus 100b
that are the same as or correspond to the elements in the
refrigeration cycle apparatus 100a, and the detailed description of
such elements is omitted. The description of the refrigeration
cycle apparatus 100a is applicable to the refrigeration cycle
apparatus 100b as long as no technical contradiction arises.
[0064] The refrigeration cycle apparatus 100b includes an
upstream-side supply passage 91b and a return passage 92b instead
of the upstream-side supply passage 91a and the return passage 92a.
The upstream-side supply passage 91b diverges from the
condensation-side circulation circuit 7 at a position downstream of
the exit of the heat-radiation-side liquid carrying pump 71 in the
condensation-side circulation circuit 7. The upstream-side supply
passage 91b is a passage for supplying a refrigerant to the
lubricant supply passage 30 of the turbomachine 1a. For example,
the upstream-side supply passage 91b diverges from the
condensation-side circulation circuit 7 at a position between the
exit of the heat-radiation-side liquid carrying pump 71 and the
entrance of the heat-radiation heat exchanger 72. Further, the
upstream-side supply passage 91b is connected to the turbomachine
1a so as to communicate with the lubricant supply passage 30. For
example, the refrigerant that travels through the upstream-side
supply passage 91b passes through the supply hole 41 to be supplied
to the storage portion 40. As described above, the refrigerant to
which pressure has been applied with the heat-radiation-side liquid
carrying pump 71 passes through the upstream-side supply passage
91b to be supplied to the lubricant supply passage 30 as the
lubricant. In this case, the discharge pressure of the
heat-radiation-side liquid carrying pump 71 is desirably set so
that the pressure of the refrigerant at the inlet 33 of the
lubricant supply passage 30 is equal to or more than the saturated
vapor pressure.
[0065] The upstream-side supply passage 91b may diverge from the
condensation-side circulation circuit 7 at a position between the
exit of the heat-radiation heat exchanger 72 and the condensation
mechanism 4 in the condensation-side circulation circuit 7. Also in
this case, part of the refrigerant of the refrigeration cycle
apparatus 100b may be supplied to the lubricant supply passage 30
as the lubricant.
[0066] The return passage 92b is a passage for returning the
refrigerant supplied to the lubricant supply passage 30 through the
upstream-side supply passage 91b to the main circuit 5. For
example, the return passage 92b communicates with the storage
portion 40 via the discharge hole 42. Further, the return passage
92b is connected to the condensation mechanism 4. The refrigerant
stored in the storage portion 40 is guided to the return passage
92b through the discharge hole 42 to flow through the return
passage 92b and is returned into the condensation mechanism 4. The
return passage 92a may be connected to the evaporation mechanism 2
so as to return the refrigerant to the evaporation mechanism 2.
[0067] According to the present embodiment, with the rotation of
the rotation shaft, the refrigerant as the lubricant is supplied
under pressure to the bearing through the lubricant supply passage
in the turbomachine. Accordingly, the pressure of the refrigerant
supplied as the lubricant increases and the evaporation of the
refrigerant as the lubricant or the occurrence of the cavitation
may be suppressed in the bearing. According to the present
embodiment, the refrigerant as the lubricant is a refrigerant whose
saturated vapor pressure is a negative pressure at ordinary
temperature. As described above, when the refrigerant whose
saturated vapor pressure is a negative pressure at ordinary
temperature is used as an operating fluid, the turbomachine needs
the number of rotations that is very large as the number of
rotations of a rotation body. Since in the refrigeration cycle
apparatus according to the present embodiment, the centrifugal
force produced through the large number of rotations may be
utilized to apply pressure to the refrigerant, high pressure may be
applied to the lubricant supplied to the bearing through the
lubricant supply passage. As a result, shortage of the lubricant in
the bearing may be prevented and the reliability of the
turbomachine may increase. In addition, the performance that the
external pump of the turbomachine for supplying the refrigerant as
the lubricant to the lubricant supply passage is desired to offer
may be reduced and accordingly, the external pump may be downsized
or the cost of the refrigeration cycle apparatus may be
lowered.
[0068] For example, when water is used as an operating fluid, the
number of rotations of the rotation body in the turbomachine is
very large, which is in a range from approximately 75 thousand to
90 thousand rpm. In this case, depending on the design, the
pressure of the refrigerant liquid supplied between the rotation
shaft and the bearing is in a range from approximately 0.5 to 1
MPaA. In contrast, when the turbomachine according to the present
disclosure is not used, that is, for example, the turbomachine in
the study stage, in which the rotation shaft has no lubricant
supply passage, is used, the discharge pressure of the external
pump of the turbomachine is desired to be in a range from
approximately 300 to 500 KPaA so as to suppress the evaporation of
the refrigerant and the occurrence of cavitation in the bearing. In
contrast, the discharge pressure of the external pump of the
turbomachine according to the present embodiment, which is the
heat-absorption-side liquid carrying pump 61 illustrated in FIG. 9,
is in a range from approximately 150 to 180 KPaA. As described
above, according to the present embodiment, the performance that
the external pump of the turbomachine is desired to offer may be
reduced and accordingly, the external pump may be downsized or the
cost of the refrigeration cycle apparatus may be lowered.
[Variations]
[0069] The refrigeration cycle apparatus 100a and the refrigeration
cycle apparatus 100b may be changed in various terms. For example,
the turbomachine 1a may include compression mechanisms of a
plurality of stages. In this case, an intermediate cooler for
cooling the refrigerant may be provided between the compression
mechanisms. For example, when the turbomachine 1a includes
compression mechanisms of two stages, the temperature of the
refrigerant vapor discharged from the compression mechanism at the
first stage is 110.degree. C. The temperature of the refrigerant
vapor discharged from the compression mechanism at the second stage
is, for example, 170.degree. C. When an intermediate cooler is
provided between the compression mechanism at the first stage and
the compression mechanism at the second stage, the refrigerant
vapor discharged from the compression mechanism at the first stage
is cooled by the intermediate cooler. In this case, the temperature
of the refrigerant vapor sucked into the compression mechanism at
the second stage is, for example, 45.degree. C.
[0070] The turbomachine 1a and another compressor may be connected
in series. The other compressor may be a positive-displacement
compressor or a turbocompressor. In this case, an intermediate
cooler may be provided between the turbomachine 1a and the other
compressor.
[0071] The passage 5c may be provided with an expansion mechanism,
such as a capillary or an expansion valve.
[0072] In the condensation mechanism 4, an ejector 4b illustrated
in FIG. 11 may be used. As illustrated in FIG. 11, the ejector 4b
includes a first nozzle 80, a second nozzle 81, a mixing unit 82,
and a diffuser unit 83. The passage 7c is connected to the first
nozzle 80. The refrigerant liquid that flows out from the
heat-radiation heat exchanger 72 through the passage 7c is supplied
to the first nozzle 80 as a driving flow. The passage 5b is
connected to the second nozzle 81. The temperature of the
refrigerant liquid ejected from the first nozzle 80 is lowered by
the heat-radiation heat exchanger 72. Thus, the ejection of the
refrigerant liquid from the first nozzle 80 causes the pressure of
the mixing unit 82 to be lower than the pressure of the passage 5b.
Consequently, the refrigerant vapor with pressure equal to or lower
than the atmospheric pressure is continuously sucked into the
second nozzle 81 through the passage 5b.
[0073] The refrigerant liquid ejected from the first nozzle 80
while accelerating and the refrigerant vapor ejected from the
second nozzle 81 while expanding and accelerating are mixed in the
mixing unit 82. Then, a refrigerant mixture with a small quality
(dryness) is generated because of first condensation caused by the
difference in temperature between the refrigerant liquid and the
refrigerant vapor and second condensation caused by the pressure
raising effect based on the transportation of energy between the
refrigerant liquid and the refrigerant vapor and the transportation
of momentum between the refrigerant liquid and the refrigerant
vapor. When the quality of the refrigerant mixture is not zero, the
velocity of flow of the refrigerant mixture exceeds the velocity of
sound of two-phase flow and abrupt rising of the pressure occurs,
and the condensation is further promoted. The generated refrigerant
mixture is a refrigerant in a liquid-phase state or a gas-liquid
two-phase state of a very small quality. After that, the diffuser
unit 83 regains static pressure by reducing the velocity of the
refrigerant mixture. In the ejector 4b configured as described
above, the temperature and the pressure of the refrigerant
rise.
[0074] The ejector 4b further includes a needle valve 84 and a
servo actuator 85. The needle valve 84 and the servo actuator 85
are flow-rate regulators for regulating the flow rate of the
refrigerant liquid as a driving flow. The needle valve 84 enables
the cross-sectional area of an orifice at the tip of the first
nozzle 80 to be changed. The servo actuator 85 enables the position
of the needle valve 84 to be adjusted. Thus, the flow rate of the
refrigerant liquid that flows through the first nozzle 80 may be
regulated.
[0075] The refrigeration cycle apparatus according to the present
disclosure is useful for a home air conditioner or an industrial
air conditioner in particular. Moreover, the refrigeration cycle
apparatus according to the present disclosure is applicable to a
chiller or a heat pump.
* * * * *