U.S. patent application number 09/834640 was filed with the patent office on 2001-09-27 for refrigerating apparatus.
Invention is credited to Amo, Yoshikazu, Fujita, Makoto.
Application Number | 20010023596 09/834640 |
Document ID | / |
Family ID | 26526259 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010023596 |
Kind Code |
A1 |
Fujita, Makoto ; et
al. |
September 27, 2001 |
Refrigerating apparatus
Abstract
A liquid injection type scroll compressor is used to a
refrigerating apparatus using hydrocarbon fluoride refrigerant
which does not contain chlorine (HFC-125/HFC-143a/HFC-134a) as an
operating fluid and an amount of an injected liquid is controlled
according to a discharge temperature of the compressor. Further,
ester oil and/or ether oil is used as refrigerator oil and a dryer
is disposed in a refrigerating cycle. With this arrangement, a
refrigerating cycle operation can be stably realized in a wide
range without almost changing the arrangement of a conventional
refrigerating apparatus.
Inventors: |
Fujita, Makoto;
(Shizuoka-ken, JP) ; Amo, Yoshikazu;
(Shizuoka-ken, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
26526259 |
Appl. No.: |
09/834640 |
Filed: |
April 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09834640 |
Apr 16, 2001 |
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09540283 |
Mar 31, 2000 |
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6240736 |
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09540283 |
Mar 31, 2000 |
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09187349 |
Nov 6, 1998 |
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6098421 |
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09187349 |
Nov 6, 1998 |
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08831769 |
Apr 2, 1997 |
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5910161 |
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08831769 |
Apr 2, 1997 |
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08528037 |
Sep 14, 1995 |
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5685163 |
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Current U.S.
Class: |
62/505 ; 252/67;
62/114 |
Current CPC
Class: |
F04C 29/0092 20130101;
F25B 2700/21152 20130101; F25B 31/008 20130101; F04C 29/0014
20130101; F04C 2210/26 20130101; C09K 5/045 20130101; F04C 2210/14
20130101; F25B 2700/21161 20130101; F04C 2270/195 20130101; F04C
2270/44 20130101; C09K 2205/22 20130101; F25B 2700/2116 20130101;
F25B 9/006 20130101; F25B 31/002 20130101 |
Class at
Publication: |
62/505 ; 62/114;
252/67 |
International
Class: |
F25B 031/00; F25D
001/00; C09K 005/00; C10M 101/00; F25B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 20, 1994 |
JP |
6-224769 |
Claims
What is claimed is:
1. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a compressor, a condenser, a liquid
receiver, an accumulator, an expansion valve and an evaporator,
wherein a mixed refrigerant containing at least R-125 and R-143a is
used as a refrigerant for said refrigerating cycle, ester oil
and/or ether oil is used as refrigerator oil and a liquid injection
type scroll compressor is used as said compressor.
2. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a compressor, a condenser, a liquid
receiver, an accumulator, an expansion valve and an evaporator,
wherein a triple-mixed refrigerant composed of 40-48 wt % of R-125,
47-57 wt % of R-143a and up to 10 wt % of R-134a is used as a
refrigerant for said refrigerating cycle, ester oil and/or ether
oil is used as refrigerator oil and a liquid injection type scroll
compressor is used as said compressor.
3. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a compressor, a condenser, a liquid
receiver, an accumulator, an expansion valve and an evaporator,
wherein a triple-mixed refrigerant composed of 40-48 wt % of R-125,
47-57 wt % of R-143a and up to 10 wt % of R-134a is used as a
refrigerant for said refrigerating cycle, ester oil and/or ether
oil is used as refrigerator oil, said compressor is composed of a
scroll compressor, the downstream side of said condenser is
connected to said scroll compressor through a liquid injection
piping, and means for controlling an amount of a liquid injected
into said compressor is provided in said liquid injection
piping.
4. A refrigerating apparatus according to claim 3, wherein said
refrigerator oil is mainly composed of ester oil of fatty acid and
having a dynamic viscosity of 2-70 cSt 40.degree. C. and 1-9 cSt at
100.degree. C. and at least two ester linkages in a molecule.
5. A refrigerating apparatus according to claim 3, wherein said
condenser uses a heat exchanger whose piping has a diameter smaller
than the refrigerant piping of a heat exchanger constituting said
evaporator.
6. A refrigerating apparatus according to claim 3, wherein the
refrigerating piping of said heat exchanger constituting said
condenser has a diameter of about 7 mm.
7. A refrigerating apparatus according to claim 3, wherein an
amount of a liquid injected into said scroll compressor is
controlled so that an evaporating temperature of said evaporator
covers a range of -60 to +5.degree. C.
8. A refrigerating apparatus according to claim 3, wherein said
liquid injection amount control means provided in said liquid
injection piping includes an injection valve or an electronic
expansion valve provided in said liquid injection piping so as to
control an amount of an injected liquid.
9. A refrigerating apparatus according to claim 1, wherein a bypass
piping is provided to connect the discharge side piping of said
compressor to the outlet side piping of said evaporator and wherein
an electromagnetic valve and a check valve are provided in said
bypass piping.
10. A refrigerating apparatus according to claim 3, wherein said
liquid injection amount control means is an electronic expansion
valve provided in said liquid injection piping and a controller is
provided to adjust an amount of an injected liquid by controlling a
degree of opening of said electronic expansion valve in response to
a discharge said temperature of said compressor.
11. A refrigerating apparatus, comprising: a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, an accumulator, an expansion valve
and an evaporator; a triple-mixed refrigerant composed of 40-48 wt
% of R-125, 47-57 wt % of R-143a and up to 10 wt % of R-134a used
as a refrigerant for said refrigerating cycle; refrigerator oil
composed of ester oil; a liquid injection piping connecting the
downstream side of said condenser to said scroll compressor; means
provided in said liquid injection piping for controlling an amount
of a liquid injected into said compressor; a
revolution-controllable motor for driving said scroll compressor; a
blower for supplying external air to said condenser and a
revolution controllable motor for said blower; means for detecting
a discharge temperature of said compressor; means for detecting a
liquid temperature of said condenser; and means for detecting a
temperature of intake air to said condenser, wherein said liquid
injection amount control means and the motor of said blower are
controlled according to values detected by said detecting
means.
12. A refrigerating apparatus according to claim 11, wherein a
pressure controller is provided which detects a pressure of said
condenser and decreases, when the pressure reaches a preset high
pressure value, a capacity of said compressor by decreasing
revolutions of said compressor motor, whereas increases, when the
pressure reaches a preset low pressure value, a capacity of said
compressor by increasing revolutions of said compressor motor.
13. A refrigerating apparatus according to claim 12, wherein when a
pressure reaches the preset high pressure value, said pressure
controller decreases a high pressure by controlling revolutions of
said blower motor to its full speed, whereas when the pressure
reaches the preset low pressure value, said pressure controller
increases the high pressure by decreasing revolutions of said
blower motor.
14. A refrigerating apparatus according to claim 11, wherein a
dryer is disposed in said refrigerating cycle to remove water mixed
into said refrigerating cycle and a desiccating agent used for said
dryer is composed of synthesized zeolite in which each of fine
holes extending to molecule adsorbing cavities in a crystal
structure has a diameter equal to or less than 3.3 angstroms which
is smaller than a molecule of the hydrocarbon fluoride refrigerant
which does not contain chloride and larger than a molecule of
water.
15. A refrigerating apparatus, comprising: a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, a dryer, an expansion valve, an
evaporator, a strainer and an accumulator; a triple-mixed
refrigerant composed of 40-48 wt % of R-125, 47-57 wt % of R-143a
and up to 10 wt % of R-134a used as a refrigerant of said
refrigerating cycle; refrigerator oil composed of ester oil; a
liquid injection piping connecting the downstream side of said
condenser to said scroll compressor; means provided in said liquid
injection piping for controlling an amount of a liquid injected
into said compressor, wherein a desiccating agent used for said
dryer is composed of synthesized zeolite in which each of fine
holes extending to molecule adsorbing cavities in a crystal
structure has a diameter equal to or less than 3.3 angstroms which
is smaller than a molecule of the hydrocarbon fluoride refrigerant
which does not contain chloride and larger than a molecule of
water.
16. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a compressor, a condenser, a liquid
receiver, an accumulator, an expansion valve and an evaporator,
wherein a double-mixed refrigerant composed of R-125 and R-143a is
used as a refrigerant for said refrigerating cycle, ester oil is
used as refrigerator oil, said compressor is composed of a scroll
compressor, the downstream side of said condenser is connected to
said scroll compressor through a liquid injection piping, and means
for controlling an amount of a liquid injected into said compressor
is provided in said liquid injection piping.
17. A refrigerating apparatus according to claim 16, wherein said
refrigerator oil is mainly composed of ester oil of fatty acid and
having a dynamic viscosity of 2-70 cSt 40.degree. C. and 1-9 cSt at
100.degree. C. and at least two ester linkages in a molecule.
18. A refrigerating apparatus according to claim 16, wherein said
condenser uses a heat exchanger whose piping has a diameter smaller
than the refrigerant piping of a heat exchanger constituting said
evaporator.
19. A refrigerating apparatus according to claim 16, wherein the
refrigerating piping of said heat exchanger constituting said
condenser has a diameter of about 7 mm.
20. A refrigerating apparatus according to claim 16, wherein an
amount of a liquid injected into said scroll compressor is
controlled so that an evaporating temperature of said evaporator
covers a range of -60 to +5.degree. C.
21. A refrigerating apparatus according to claim 16, wherein said
liquid injection amount control means provided in said liquid
injection piping includes an injection valve or an electronic
expansion valve provided in said liquid injection piping so as to
control an amount of an injected liquid.
22. A refrigerating apparatus according to claim 16, wherein said
liquid injection amount control means is an electronic expansion
valve provided in said liquid injection piping and a controller is
provided to adjust an amount of an injected liquid by controlling a
degree of opening of said electronic expansion valve in response to
a discharge said temperature of said compressor.
23. A refrigerating apparatus, comprising: a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, an accumulator, an expansion valve
and an evaporator; a double-mixed refrigerant composed of R-125 and
R-143a used as a refrigerant for said refrigerating cycle;
refrigerator oil composed of ester oil; a liquid injection piping
connecting the downstream side of said condenser to said scroll
compressor; means provided in said liquid injection piping for
controlling an amount of a liquid injected into said compressor; a
revolution-controllable motor for driving said scroll compressor; a
blower for supplying external air to said condenser and a
revolution controllable motor for said blower; means for detecting
a discharge temperature of said compressor; means for detecting a
liquid temperature of said condenser; and means for detecting a
temperature of intake air to said condenser, wherein said liquid
injection amount control means and the motor of said blower are
controlled according to values detected by said detecting
means.
24. A refrigerating apparatus according to claim 23, wherein a
pressure controller is provided which detects a pressure of said
condenser and decreases, when the pressure reaches a preset high
pressure value, a capacity of said compressor by decreasing
revolutions of said compressor motor, whereas increases, when the
pressure reaches a preset low pressure value, a capacity of said
compressor by increasing revolutions of said compressor motor.
25. A refrigerating apparatus according to claim 24, wherein when a
pressure reaches the preset high pressure value, said pressure
controller decreases a high pressure by controlling revolutions of
said blower motor to its full speed, whereas when the pressure
reaches the preset low pressure value, said pressure controller
increases the high pressure by decreasing revolutions of said
blower motor.
26. A refrigerating apparatus according to claim 23, wherein a
dryer is disposed in said refrigerating cycle to remove water mixed
into said refrigerating cycle and a desiccating agent used for said
dryer is composed of synthesized zeolite in which each of fine
holes extending to molecule adsorbing cavities in a crystal
structure has a diameter equal to or less than 3.3 angstroms which
is smaller than a molecule of the hydrocarbon fluoride refrigerant
which does not contain chloride and larger than a molecule of
water.
27. A refrigerating apparatus, comprising: a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, a dryer, an expansion valve, an
evaporator, a strainer and an accumulator; a double-mixed
refrigerant composed of R-125 and R-143a used as a refrigerant of
said refrigerating cycle; refrigerator oil composed of ester oil; a
liquid injection piping connecting the downstream side of said
condenser to said scroll compressor; means provided in said liquid
injection piping for controlling an amount of a liquid injected
into said compressor, wherein a desiccating agent used for said
dryer is composed of synthesized zeolite in which each of fine
holes extending to molecule adsorbing cavities in a crystal
structure has a diameter equal to or less than 3.3 angstroms which
is smaller than a molecule of the hydrocarbon fluoride refrigerant
which does not contain chloride and larger than a molecule of
water.
28. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a scroll compressor, a condenser, a liquid
receiver, and accumulator, an expansion valve and an evaporator,
wherein the downstream side of said condenser and said scroll
compressor are connected through a liquid injection piping, means
for controlling an amount of a liquid injected into said compressor
is provided in said liquid injection piping, a mixed refrigerant
comprising at least R-125 and R-143a is used as a refrigerant or
said refrigerating cycle, and an ester oil used as a refrigerant
oil has a dynamic viscosity of 2-70 cSt at 40.degree. C. and 1-9
cSt at 100.degree. C.
29. The refrigerating apparatus according to claim 28, wherein a
base oil of said refrigerator oil is an ester oil of fatty acid of
least two ester linkages in a molecule.
30. A refrigerating apparatus constituting a refrigerating cycle by
sequentially connecting a scroll compressor, a condenser, a liquid
receiver, an accumulator, an expansion valve and an evaporator,
wherein the downstream side of said condenser and said scroll
compressor are connected through a liuqid injection piping, means
for controlling an amount of a liquid injected into said compressor
is provided in said liquid injection piping, a refrigerant composed
at least of R-125 and R-143a is used as a refrigerant for said
refrigerating cycle, an ester oil used as a refrigerant oil has a
dynamic viscosity of 2-70 cSt at 40.degree. C. and 1-9 cSt at
100.degree. C., and said liquid injection amount control means
includes an injection valve or an electronic expansion valve
provided in said liquid injection piping so as to control an amount
of an injected liquid.
Description
CROSS REFERENCE TO RELATED INVENTIONS
[0001] This application is a continuation-in-part of application
Ser. No. 08/528,037, filed Sep. 14, 1997, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a refrigerating apparatus
used to air conditioners, refrigerators and the like, and more
specifically, to a refrigerating apparatus using a mixed
refrigerant which does not contain chlorine.
[0004] 2. Description of the Prior Art
[0005] Conventionally, so-called hydrocarbon fluoride refrigerants
containing chloride such as CFC, HCFC and such like are widely used
as an operating fluid for a refrigerating cycle because they are a
most suitable substance as a refrigerant due to their excellent
thermodynamic property and stability.
[0006] As described in, for example, Japanese Patent Publication
Laid-Open No. 3-63461, Japanese Patent Publication Laid-Open No.
59-84049, Japanese Patent Publication Laid-Open No. 5-172408 and
the like, it is well known that refrigerating apparatuses using
these refrigerants prevent the overheat of compressors and achieve
a wide range of an operating pressure.
[0007] Hydrocarbon fluoride substances containing chloride are not
decomposed due to their stability and reach the stratosphere by
convection. It is found that since these substances are decomposed
by strong ultraviolet rays in the sky and separate chlorine atoms
which react with ozone, they have an action for destroying the
ozone layer. It is determined to entirely abolish the hydrocarbon
fluoride substances containing chloride to protect the ozone layer
which has a function to cut off ultraviolet rays harmful to human
bodies in the sky. Although HCFC-22 which is widely used as a
refrigerant for air conditioners and refrigerators is also an
object to be abolished, since it is less effective to the
destruction of the ozone layer than CFCs designated as specific
Freons, a longer period of grace is admitted to the substance. It
is essential to develop replacement refrigerants and refrigerating
apparatuses applicable to the replacement refrigerants in the
period of grace.
[0008] At present, HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a
and such like, for example, as hydrocarbon fluoride refrigerants
which do not contain chloride causing the destruction of the ozone
layer are examined as new refrigerants to be replaced with
conventional refrigerants such as HCF-C22 and such like and any one
of them or a combination of a plurality of them is influential.
Development is carried out aiming at a refrigerant having a
performance factor such as a refrigerating capacity, efficiency and
the like and a cyclic state such as an operating pressure,
temperature and the like equivalent or near to those of
conventional refrigerants. This is because that a caution is paid
to permit the replacement refrigerants to be handled in the same
manner as conventional refrigerants so that the new refrigerants
can be employed with a minimum change of the specification of
products and manufacturing apparatuses which have been applied to
conventional refrigerants.
[0009] Incidentally, a compressor, cycle auxiliary components and a
cycle control device must be arranged to comply with the new
refrigerants so that a performance equivalent to that of
conventional products is maintained and a cycle state such as a
range of an operating pressure, temperature and the like is
stabilized at all times. Further, when different refrigerants are
used, refrigerator oils must be also changed to comply with the new
different refrigerants. That is, although chlorine has a function
for assisting compatibility with oil, new refrigerants do not
contain chloride causing the destruction of the ozone layer as
described above. Thus, the compatibility of the new refrigerants
with conventional refrigerator oils, which are mainly composed of
mineral oils, alkylbenzene and such like and have been widely used
to conventional refrigerants, is greatly lowered and thus the new
refrigerants cannot be used with the conventional refrigerator
oils. To cope with this problem, there is developed new
refrigerator oil which can secure the compatibility with the new
refrigerant by the molecular polarity of ether and ester.
[0010] Incidentally, when conventional refrigerator oil and a
chlorine substance contained in a conventional refrigerant are
mixed in a refrigerating cycle to which a new refrigerant is
applied, the new refrigerant and new refrigerator oil are
chemically changed by the mixing of them, and, for example, a
material used in the cooling cycle may be corroded by the
occurrence of acid. Thus, a problem arises in that the reliability
of products is greatly lowered.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide a
refrigerating apparatus which can realize a cycle state such as a
performance, operating pressure, temperature and the like which are
equivalent to that of a conventional refrigerating apparatus using
a new refrigerant and new refrigerator oil while securing the
reliability of components without damaging the performance
thereof.
[0012] To achieve the above object, a first feature of the present
invention resides in an refrigerating apparatus constituting a
refrigerating cycle by sequentially connecting a compressor, a
condenser, a liquid receiver, an accumulator, an expansion valve
and an evaporator, wherein a mixed refrigerant containing at least
R-125 and R-143a is used as a refrigerant for the refrigerating
cycle, ester oil and/or ether oil is used as refrigerator oil and a
liquid injection type scroll compressor is used as the
compressor.
[0013] A second feature of the present invention resides in that a
triple-mixed refrigerant composed of 40-48 wt %, e.g., 44 wt % of
R-125, 47-57 wt %, e.g., 52 wt % of R-143a and up to 10 wt %, e.g.,
4 wt % of R-134a is used as a refrigerant for a refrigerating
cycle, ester oil and/or ether oil is used as refrigerator oil and
further a liquid injection type scroll compressor is used as a
compressor.
[0014] An example of the liquid injection type scroll compressor is
arranged such that the downstream side of the condenser is
connected to the scroll compressor through a liquid injection
piping, and means for controlling an amount of a liquid injected
into to the compressor is provided in the liquid injection
piping.
[0015] It is preferable that the refrigerator oil is mainly
composed of ester oil of fatty acid and having a dynamic viscosity
of 2-70 cSt at 40.degree. C. and 1-9 cSt at 100.degree. C. and at
least two ester linkages in a molecule. Further, the condenser can
be arranged as a heat exchanger whose piping has a diameter smaller
than the refrigerant piping of a heat exchanger constituting the
evaporator in order to increase a heat exchanging efficiency in the
condenser. An electronic expansion valve disposed to the liquid
injection piping is most suitable as the liquid injection amount
control means and a controller is provided to adjust an amount of
an injected liquid by controlling a degree of opening of the
electronic expansion valve in response to a discharge side
temperature of the compressor.
[0016] A third feature of the present invention resides in a
refrigerating apparatus, which comprises a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, an accumulator, an expansion valve
and an evaporator, a triple-mixed refrigerant composed of 40-48 wt
%, e.g., 44 wt % of R-125, 47-57 wt %, e.g., 52 wt % of R-143a and
up to 10 wt %, e.g., 4 wt % of R-134a used as a refrigerant for the
refrigerating cycle, refrigerator oil composed of ester oil and/or
ether oil, a liquid injection piping connecting the downstream side
of the condenser to the scroll compressor, means provided with the
liquid injection piping for controlling an amount of a liquid
injected into the compressor, a revolution-controllable motor for
driving the scroll compressor, a blower for supplying external air
to the condenser and a revolution-controllable motor for the
blower, means for detecting a discharge temperature of the
compressor, means for detecting a liquid temperature of the
condenser, and means for detecting a temperature of intake air to
the condenser, wherein the liquid injection amount control means
and the motor of the blower are controlled according to values
detected by the detecting means. It is preferable to provide a
pressure controller which detects a pressure of the condenser and
decreases, when the pressure reaches a preset high pressure value,
a capacity of the compressor by decreasing revolutions of the
compressor motor, whereas increases, when the pressure reaches a
present low pressure value, a capacity of the compressor by
increasing revolutions of the compressor motor. Further, it is
effective that when a pressure reaches the preset high pressure
value, the pressure controller decreases a high pressure by
controlling revolutions of the blower motor to its full speed,
whereas when the pressure reaches the preset low pressure value,
the pressure controller increases the high pressure by decreasing
revolutions of the blower motor.
[0017] A fourth feature of the present invention resides in a
refrigerating apparatus, which comprises a refrigerating cycle
composed by sequentially connecting a scroll compressor, a
condenser, a liquid receiver, a dryer, an expansion valve, an
evaporator, a strainer and an accumulator, a triple-mixed
refrigerant composes of 40-48 wt %, e.g., 44 wt % of R-125, 47-57
wt %, e.g., 52 wt % of R-143a and up to 10 wt %, e.g., 4 wt % of
R-134a used as a refrigerant of the refrigerating cycle,
refrigerator oil composed of ester oil and/or ether oil, a liquid
injection piping connecting the downstream side of the condenser to
the scroll compressor, means provided with the liquid injection
piping for controlling an amount of a liquid injected into the
compressor, wherein a desiccating agent used for the dryer is
composed of synthesized zeolite in which each of fine holes
extending to molecule adsorbing cavities in a crystal structure has
a diameter equal to or less than 3.3 angstroms which is smaller
than a molecule of the hydrocarbon fluoride refrigerant which does
not contain chloride and larger than a molecule of water.
[0018] A fifth feature of the present invention resides in that a
double-mixed refrigerant composed of R-125 and R-143a, e.g., 50 wt
% of R-125 and 50 wt % of R-143a, is used as a refrigerant for a
refrigerating cycle, ester oil and/or ether oil is used as
refrigerator oil and further a liquid injection type scroll
compressor is used as a compressor.
[0019] Even the refrigerating apparatus using the above refrigerant
can achieve an operating pressure, temperature and performance
equivalent to those of a refrigerating apparatus using a
conventional refrigerant by employing the liquid injection type
scroll compressor.
[0020] That is, when an evaporating temperature is low, an amount
of a refrigerant circulating in the refrigerating cycle is
decreased and a temperature of a gas discharged from the compressor
is increased. As a result, there is caused a danger that the
compressor motor and the like may be seized, and the like. In the
present invention, however, the compressor is prevented from being
overheated and can be operated in a wide evaporating temperature by
injecting a high pressure liquid refrigerant into the section side
or intermediate compression chamber of the compressor through the
pressure reduction unit.
[0021] A capillary system, an injection valve system, an electronic
expansion valve system or a system combining them is employed as
the liquid injection system so that a flow rate of an injected
liquid can be made constant to keep a temperature of a discharged
gas constant. As a result, a cycle can be stabilized and
reliability can be secured.
[0022] Further, compatibility with the new refrigerant can be
secured by the employment of the ester oil and/or ether oil as the
new refrigerator oil, whereby the reliability and performance of
components can be secured.
[0023] As described above, the present invention can realize the
refrigerating apparatus whose capacity can be controlled in a wide
range covering an evaporating temperature of the evaporator of
-60.degree. C. to +5.degree. C. using the new refrigerant which
does not contain chlorine causing the destruction of the ozone
layer, without almost changing the arrangement of a conventional
refrigerating apparatus.
[0024] Other features, objects and merits of the present invention
will become apparent from the following description when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a system diagram of a refrigerating apparatus
showing an example of the present invention;
[0026] FIG. 2 is a system diagram of the main portion showing
another example of a liquid injection arrangement in FIG. 1;
[0027] FIG. 3 is a system diagram of the main portion showing a
still another example of the liquid injection arrangement in FIG.
1;
[0028] FIG. 4 is a system diagram of the main portion showing a
further example of the liquid injection arrangement in FIG. 1;
and
[0029] FIG. 5 is a system diagram of the main portion showing a
still further example of the liquid injection arrangement in FIG.
1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] In this embodiment, a triple-mixed hydrocarbon fluoride
refrigerant which is composed of 40-48 wt %, e.g., 44 wt % of
HFC-125, 47-57 wt %, e.g., 52 wt % of HFC-143a and up to 10 wt %,
e.g., 4 wt % of HFC-134a and does not contain chlorine is used as a
refrigerant for a refrigerating cycle and a liquid injection type
scroll compressor is used as a compressor. Alternatively, a
double-mixed hydrocarbon fluoride refrigerant which is composed of
HFC-125 and HFC-143a, e.g., 50 wt % of HFC-125 and 50 wt % of
HFC-143a, and does not contain chlorine is used as a refrigerant
for the refrigerating cycle. Further, ester oil (for example,
disclosed in Japanese Patent Publication Laid-Open No. 4-183788) as
a new refrigerator oil and/or ether oil is used and a means
disclosed for example, Japanese Patent Publication-Laid-Open No.
5-231263 is used as a means for preventing the mixing of a chlorine
substance in order to secure the reliability of an apparatus.
[0031] A specific embodiment of the present invention will be
described below with reference to FIG. 1.
[0032] As shown in FIG. 1, a refrigerating apparatus of the
embodiment constitutes a refrigerating cycle by sequentially
connecting a scroll compressor 1, a condenser 2, a liquid receiver
3, a dryer 4, expansion valves 51 and 52, evaporators 61 and 62, a
strainer 18, and an accumulator 7. Further, the condenser 2 is
provided with two sets of blower motors 81 and 82 and propeller
fans 91 and 92 for supplying external air as shown in FIG. 1.
[0033] A hydrocarbon fluoride refrigerant which does not contain
chlorine causing the destruction of the ozone layer is used as a
refrigerant for the refrigerating cycle.
[0034] HFC-32, HFC-125, HFC-134a, HFC-143a, HFC-152a and the like
are used as this type of a refrigerant and any one of them is
independently used or a plurality of them are used as a mixed
refrigerant. This embodiment uses a triple-mixed refrigerant
composed of 44 wt % of R-125, 52 wt % of R-143a and 4 wt % of
R-134a. An alternative embodiment uses a double-mixed refrigerant
composed of 50 wt % of R-125 and 50 wt % of R-143a. Refrigerator
oil used for the refrigerating cycle must have good compatibility
with the refrigerant. While ester oil and/or ether oil may be used
as the refrigerator oil, this embodiment uses ester oil as the
refrigerator oil. It is found that preferably the ester oil is
mainly composed of ester oil of fatty acid and has a dynamic
viscosity of 2-70 cSt at 40.degree. C. and 1-9 cSt at 100.degree.
C. and at least two ester linkages in a molecule in order to cover
a temperature range of -60.degree. C. to +5.degree. C. which is the
usual specification range of a refrigerating apparatus.
[0035] This embodiment is devised as described below to realize a
refrigerating apparatus which covers the temperature range of
-60.degree. C. to +5.degree. C. in the refrigerating cycle using
the above triple-mixed refrigerant and the refrigerator oil
similarly to a conventional refrigerating apparatus using a
refrigerant containing chloride.
[0036] There is provided a protection switch 23 which is connected
to a high pressure sensor 31 for detecting a pressure of a high
pressure piping 24 and to a low pressure sensor 32 for detecting a
pressure of a low pressure piping 25, respectively so as to turn
off the switch of the operation circuit of a compressor motor when
a limit value of a high pressure or low pressure is reached.
[0037] There is provided a pressure controller 15 which detects a
pressure of the condenser 2, decreases, when the detected pressure
reaches a preset high pressure value, a capacity of the compressor
by decreasing the revolutions of the compressor motor and
increases, when the detected pressure reaches a preset low pressure
value, a capacity of the compressor by increasing the revolutions
of the compressor motor. The revolutions of the compressor motor
may be controlled stepwise using a motor capable of changing the
number of poles or controlled continuously in accordance with a
pressure value by an inverter control. Note, in this embodiment,
when a pressure is reached to the preset high pressure value by the
pressure controller 15, revolutions of each of the blower motors 81
and 82 is controlled to its full speed at the same time to decrease
the high pressure, whereas when a pressure is reached to the preset
low pressure value, the revolutions of each of the blower motors 81
and 82 is decreased to increase the high pressure.
[0038] There is provided a liquid injection piping 12 for
connecting the liquid refrigerant outlet piping 16 of the liquid
receiver 3 disposed downstream of the condenser to the scroll
compressor 1. The liquid injection piping 12 includes a strainer 11
and an electronic expansion valve 10 and a liquid refrigerant is
supplied into the intermediate pressure chamber of the scroll
compressor 1 therethrough. A controller 30 calculates amounts of
control of the electronic expansion valve 10 and the blower motors
81 and 82 by a previously input program in response to values
detected by a thermistor 26 for detecting a liquid temperature of
the condenser 2, a thermistor 27 for detecting a temperature of
intake air, i.e., a temperature of outside air supplied to the
condenser 2 and a thermistor 28 for detecting a discharge side
temperature of the compressor 1. A control signal output unit 29
outputs control signals to the blower motors 81 and 82 for the
condenser and the electronic expansion valve 10 in response to a
command from the controller 30.
[0039] The condenser 2 uses a heat exchanger whose piping has a
diameter smaller than that of heat exchangers constituting the
evaporators 61 and 62. In this embodiment, the condenser 2 is
composed of a heat exchanger whose piping has a small diameter of
about 7 mm so as to cover the above temperature range of the
refrigerating apparatus.
[0040] A bypass piping 22 connected to a discharge gas piping 13 is
also connected to the outlet piping of the evaporators 61 and 62,
i.e., to a refrigerant gas piping 17 through an electromagnetic
valve 20 and a check valve 21. This is for the purpose of causing a
high pressure gas to escape to a low pressure side before the
compressor 1 starts and thus causing the electromagnetic valve 20
to "open" for a predetermined period of time. With this
arrangement, the compressor 1 can be smoothly started by balancing
cyclic pressures on a high pressure side and a low pressure
side.
[0041] Next, the operation of this embodiment will be described
with reference to FIG. 1.
[0042] A refrigerant gas compressed by the compressor 1 is
condensed by the condenser 2 through the discharge pipe 13 and a
check valve 14, supplied to the expansion valves 51 and 52 and the
evaporators 61 and 62 through the liquid receiver 3, a liquid
refrigerant piping 16 and the drier 4 and evaporated therein to a
gas. The gas is returned to the intake side of the compressor 1
from an intake piping 19 through the refrigerant gas piping 17, the
strainer 18 and the accumulator 7.
[0043] Next, the liquid injection piping 12 will be described. A
degree of opening of the electromagnetic valve 10 is controlled
depending upon a discharge side temperature of the compressor 1.
The thermistor 28 detects the discharge temperature and compares it
with a previously input and set discharge temperature. When the
detected discharge temperature is higher than the set value, a
degree of opening of the valve 10 is increased, whereas when the
detected temperature is lower than the set value, a degree of
opening of the valve 10 is decreased. That is, a degree of opening
of the expansion valve 10 is continuously adjusted by the
controller 30 and the control signal output unit 29. As described
above, the overheat of the compressor 1 can be prevented by
controlling a discharge temperature of the compressor 1 and thus a
refrigerating cycle operation can be stably carried out.
[0044] Since an amount of a refrigerant dissolved in refrigerator
oil is increased when an outside air temperature is low, a
viscosity of the refrigerator oil is lowered. Therefore, an effect
of the refrigerator oil as a lubricant to the bearing portion of
the compressor is reduced and the bearing portion is worn. In this
embodiment, when an outside air temperature is lower than a set
temperature, a viscosity of the refrigerator oil is secured in such
a manner that a degree of opening of the electronic expansion valve
10 in the liquid injection piping 12 is decreased in response to a
temperature detected by the thermistor 27 so that an amount of a
refrigerant supplied to the compressor 1 is decreased and a
discharge side temperature of the compressor 1 is increased when it
starts to reduce an amount of the refrigerant dissolved in the
refrigerator oil in order to increase a viscosity of the
refrigerator oil even in a slight amount. With this arrangement,
the reliability of the bearing portion of the compressor can be
improved.
[0045] Since a pressure at a high pressure side is increased when
an outside air temperature is high, the high pressure is
controlled. That is, when it is found from a temperature detected
by the thermistor 26 that a temperature of a liquid refrigerant is
high at the outlet of the condenser 2, the high pressure is
decreased by increasing an amount of air to be supplied by
increasing revolutions of the blower motors 81 and 82 for the
condenser. Further, when a temperature of the liquid refrigerant is
low at the outlet of the condenser 2, the high pressure is
increased by decreasing the revolutions of the blower motors 81 and
82 for the condenser.
[0046] Further, when it is found from a temperature detected by the
thermistor 27 that an outside air temperature is high, a high
pressure is decreased by increasing an amount of air to be supplied
by increasing the revolutions of the blower motors 81 and 82 for
the condenser, whereas when the outside air temperature is low, the
high pressure is increased by decreasing an amount of air to be
supplied.
[0047] These controls are effected by controlling the revolutions
of the blower motors 81 and 82 by the controller 30 and the control
signal output unit 29.
[0048] When a pressure in the condenser 2 is higher than a set
value, a capacity control is effected by decreasing a capacity of
the scroll compressor 1 by the operation of the pressure controller
1 5 and revolutions of each of the blower motors 81 and 82 is set
to at its full speed to decrease a high pressure. When a pressure
in the condenser 2 is lower than the set value, a capacity of the
scroll compressor 1 is increased by the operation of the pressure
controller 15 and revolutions of each of the blower motors 81 and
82 is also decreased to increase a high pressure.
[0049] Note, the liquid receiver 3 includes a fusible plug 33 which
has a function for discharging a refrigerant when it is excessively
heated.
[0050] The dryer 4 has an object for removing water mixed in a
refrigerating cycle. A desiccating agent, which is used to the
dryer 4 in a refrigerating cycle employing the hydrocarbon fluoride
refrigerant which does not contain chlorine as an operation
refrigerant, is composed of synthesized zeolite in which each of
fine holes extending to molecule adsorbing cavities in a crystal
structure has a diameter equal to or less than 3.3 angstroms which
is smaller than a molecule of the hydrocarbon fluoride refrigerant
which does not contain chlorine and larger than a molecule of
water. The dryer 4 may be positioned at the oil sump in the
compressor 1, the oil sump of an oil separator or in the
accumulator 7. In this case, the number of parts can be reduced as
compared with a case that it is connected to a refrigerating cycle
piping, thus a manufacturing cost can be reduced and the leakage of
a gas caused by the improper mounting of it can be prevented.
[0051] Although the thermistors 26-28 are used in the above
refrigerating cycle as means for detecting temperatures, an ON/OFF
control by thermostats may be employed in place of the thermistors.
Although a control can be continuously effected when the
thermistors are used, the control is effected in an ON/OFF fashion
when the thermostats are employed. Further, the above control may
be effected by the controller 30 and the control signal output unit
29 by detecting pressures in place of temperatures.
[0052] Next, other examples of the liquid injecting portion in the
embodiment shown in FIG. 1 will be described with reference to FIG.
2-FIG. 5.
[0053] In an example of FIG. 2, a liquid injection control is
effected by electromagnetic valves 341 and 342 and capillaries 351
and 352. The electromagnetic valve 341 is opened simultaneously
with the start of the compressor 1 so as to prevent the increase of
a discharge side temperature of the compressor 1. When the
discharge side temperature is further increased, the increased
temperature is detected by the thermistor 28, and when it is higher
than a set temperature, the electromagnetic valve 342 is opened and
an amount of an injected liquid is increased so that the overheat
of the compressor 1 can be prevented.
[0054] An example of FIG. 3 will be described. The example of FIG.
3 is different from that of FIG. 2 in that the liquid injection
piping 1 2 is connected to the lower oil sump of the liquid
receiver 3. With this arrangement, a liquid refrigerant can be
stably used for a liquid injection control at all times.
[0055] An example of FIG. 4 will be described. The example of FIG.
4 is different from that of FIG. 1 in that only a liquid injection
control is effected. The liquid injection control in the example of
FIG. 4 is effected separately using the line of an injection valve
36 and the line of the electromagnetic valve 341 and the capillary
351. The electromagnetic valve 341 is opened simultaneously with
the start of the compressor 1 so as to prevent the increase of a
discharge side temperature of the compressor 1. Further, when it is
found by a temperature or pressure sensor 37 connected to the
discharge piping 13 that a temperature or a pressure is higher than
a set temperature or pressure, the injection valve 36 is opened,
whereas when it is lower than the set temperature or pressure, the
injection valve 36 is closed. With this arrangement, the overheat
preventing operation of the compressor 1 can be effected so that
the refrigerating cycle operation can be stably effected.
[0056] Next, an example of FIG. 5 will be described. The example of
FIG. 5 is different from that of FIG. 4 in that the liquid
injection piping 12 is connected to the lower oil sump of the
liquid receiver 3. With this arrangement, a liquid refrigerant can
be used for a liquid injection control at all times without causing
the shortage of it.
[0057] As described above, according to the present invention,
since the liquid injection type scroll compressor is used together
with the new refrigerator oil having good compatibility with the
new refrigerant, the new refrigerant which does not contain
chlorine having a possibility for destroying the ozone layer can be
used. Thus, there can be obtained an advantage that a stable
refrigerating cycle operation can be realized in a wide operating
pressure and temperature equivalent to those of a conventional
refrigerating apparatus.
[0058] Further, since water in the cycle piping can be effectively
removed by the dryer complying with the new refrigerant, the
reliability of the compressor and other cycle components can be
improved and a trouble of the refrigerating apparatus caused by
water can be prevented.
* * * * *