U.S. patent application number 11/478489 was filed with the patent office on 2007-01-04 for ejector cycle system.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Makoto Ikegami, Naohisa Ishizaka, Takuo Maehara, Hiroshi Oshitani, Takeyuki Sugiura, Hirotsugu Takeuchi, Etsuhisa Yamada.
Application Number | 20070000262 11/478489 |
Document ID | / |
Family ID | 37575859 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070000262 |
Kind Code |
A1 |
Ikegami; Makoto ; et
al. |
January 4, 2007 |
Ejector cycle system
Abstract
An ejector cycle system with a refrigerant cycle through which
refrigerant flows includes an ejector disposed downstream of a
radiator, a first evaporator that evaporates refrigerant flowing
out of the ejector, a throttling unit located in a branch passage
and depressurizes refrigerant to adjust a flow rate of refrigerant,
and a second evaporator located downstream of the throttling unit.
In the ejector cycle system, a flow ratio adjusting means adjusts a
flow ratio between a first refrigerant flow amount depressurized
and expanded in a nozzle portion of the ejector and a second
refrigerant flow amount drawn into a refrigerant suction port of
the ejector, based on a physical quantity related to at least one
of a state of refrigerant in the refrigerant cycle, a temperature
of a space to be cooled by the first and second evaporators, and an
ambient temperature of the space.
Inventors: |
Ikegami; Makoto; (Anjo-city,
JP) ; Oshitani; Hiroshi; (Toyota-city, JP) ;
Yamada; Etsuhisa; (Kariya-city, JP) ; Ishizaka;
Naohisa; (Okazaki-city, JP) ; Takeuchi;
Hirotsugu; (Nagoya-city, JP) ; Sugiura; Takeyuki;
(Anjo-city, JP) ; Maehara; Takuo; (Toyohashi-city,
JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
37575859 |
Appl. No.: |
11/478489 |
Filed: |
June 29, 2006 |
Current U.S.
Class: |
62/170 ;
62/228.1; 62/500 |
Current CPC
Class: |
F25B 41/00 20130101;
F25B 2400/12 20130101; F25B 2600/2513 20130101; F25B 2700/21151
20130101; F25B 31/002 20130101; F25B 49/02 20130101; F25B 2500/19
20130101; F25B 2600/023 20130101; F25B 2341/0012 20130101; F25B
2600/112 20130101; Y02B 30/70 20130101; F25B 2700/1933 20130101;
F25B 2700/2102 20130101; B60H 2001/3298 20130101; F25B 9/008
20130101; F25B 40/00 20130101; F25B 2309/061 20130101; F25B 2700/19
20130101; F25B 2341/0011 20130101 |
Class at
Publication: |
062/170 ;
062/500; 062/228.1 |
International
Class: |
F25B 19/02 20060101
F25B019/02; F25B 49/00 20060101 F25B049/00; F25B 1/06 20060101
F25B001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2005 |
JP |
2005-191156 |
Aug 11, 2005 |
JP |
2005-233169 |
Aug 18, 2005 |
JP |
2005-237651 |
Claims
1. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a radiator that radiates heat from
high-pressure refrigerant discharged from the compressor; an
ejector disposed downstream of the radiator, the ejector having a
nozzle portion for depressurizing and expanding refrigerant, a
refrigerant suction port through which refrigerant is drawn by a
high-speed refrigerant flow jetted from the nozzle portion, and a
pressure increasing portion for mixing refrigerant drawn through
the refrigerant suction port with the high-speed refrigerant flow
and for decelerating the mixed refrigerant flow to raise a pressure
of the refrigerant flow; a first evaporator that evaporates
refrigerant flowing out of the ejector; a branch passage that is
branched from a branch portion between the radiator and the ejector
and is coupled to the refrigerant suction port, for guiding
refrigerant from the radiator into the refrigerant suction port; a
throttling unit that is located in the branch passage and
depressurizes refrigerant to adjust a flow rate of refrigerant; a
second evaporator that is located downstream of the throttling unit
and evaporates refrigerant; and a flow ratio adjusting means which
adjusts a flow ratio between a first refrigerant flow amount
depressurized and expanded in the nozzle portion of the ejector and
a second refrigerant flow amount drawn into the refrigerant suction
port, based on at least a physical quantity related to at least one
of a state of refrigerant in the refrigerant cycle, a temperature
of a space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be
cooled.
2. The ejector cycle system according to claim 1, wherein the flow
ratio adjusting means is constructed of the ejector itself.
3. The ejector cycle system according to claim 1, wherein the flow
ratio adjusting means is constructed of the throttling unit
itself.
4. The ejector cycle system according to claim 1, wherein the flow
ratio adjusting means is constructed of a variable throttling
member that is different from the ejector and the throttling
unit.
5. The ejector cycle system according to claim 4. wherein the
variable throttling member is located between the branch portion of
the branch passage and a refrigerant inflow port of the nozzle
portion of the ejector.
6. The ejector cycle system according to claim 1, wherein the
throttling unit is a variable throttle member located between the
branch portion of the branch passage and a refrigerant inflow port
of the second evaporator.
7. The ejector cycle system according to claim 4, wherein the
variable throttling member is located at the branch portion of the
branch passage.
8. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a radiator that radiates heat from
high-pressure refrigerant discharged from the compressor; an
ejector disposed downstream of the radiator, the ejector having a
nozzle portion for depressurizing and expanding refrigerant, a
refrigerant suction port through which refrigerant is drawn by a
high-speed refrigerant flow jetted from the nozzle portion, and a
pressure increasing portion for mixing refrigerant drawn through
the refrigerant suction port with the high-speed refrigerant flow
and for decelerating the mixed refrigerant flow to raise a pressure
of the refrigerant flow; a first evaporator that evaporates
refrigerant flowing out of the ejector; a branch passage that is
branched from a branch portion between the radiator and the ejector
and is coupled to the refrigerant suction port, for guiding
refrigerant from the radiator into the refrigerant suction port; a
throttling unit that is located in the branch passage and
depressurizes refrigerant to adjust a flow rate of refrigerant; a
second evaporator that is located downstream of the throttling unit
and evaporates refrigerant; and a flow amount adjusting means which
adjusts a flow amount in the whole refrigerant cycle, based on at
least a physical quantity related to at least one of a state of
refrigerant in the refrigerant cycle, a temperature of a space to
be cooled by the first evaporator and the second evaporator, and an
ambient temperature of the space to be cooled.
9. The ejector cycle system according to claim 8, wherein the flow
amount adjusting means is located upstream of the branch portion of
the branch passage.
10. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a discharge capacity varying section that
adjusts a flow amount of refrigerant discharged from the
compressor; a radiator that radiates heat from high-pressure
refrigerant discharged from the compressor; an ejector disposed
downstream of the radiator, the ejector having a nozzle portion for
depressurizing and expanding refrigerant, a refrigerant suction
port through which refrigerant is drawn by a high-speed refrigerant
flow jetted from the nozzle portion, and a pressure increasing
portion for mixing refrigerant drawn through the refrigerant
suction port with the high-speed refrigerant flow and for
decelerating the mixed refrigerant flow to raise a pressure of the
refrigerant flow; a first evaporator that evaporates refrigerant
flowing out of the ejector; a branch passage that is branched from
a branch portion between the radiator and the ejector and is
coupled to the refrigerant suction port, for guiding refrigerant
from the radiator into the refrigerant suction port; a throttling
unit that is located in the branch passage and depressurizes
refrigerant to adjust a flow rate of refrigerant; and a second
evaporator that is located downstream of the throttling unit and
evaporates refrigerant, wherein the discharge capacity varying
means adjusts the flow amount of refrigerant discharged from the
compressor, based on at least a physical quantity related to at
least one of a state of refrigerant in the refrigerant cycle, a
temperature of a space to be cooled by the first evaporator and the
second evaporator, and an ambient temperature of the space to be
cooled.
11. The ejector cycle system according to claim 10, wherein the
compressor is a displacement variable compressor, and wherein the
discharge capacity varying section is an electrical capacity
control valve which adjusts the flow amount of the refrigerant
discharged from the compressor by changing a discharge capacity of
the compressor.
12. The ejector cycle system according to claim 10, wherein the
discharge capacity varying section is an electromagnetic clutch
which adjusts the flow amount of the refrigerant discharged from
the compressor by changing a ratio between an operation state and a
non-operation state of the compressor.
13. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a radiator that radiates heat from
high-pressure refrigerant discharged from the compressor; an
ejector disposed downstream of the radiator, the ejector having a
nozzle portion for depressurizing and expanding refrigerant, a
refrigerant suction port through which refrigerant is drawn by a
high-speed refrigerant flow jetted from the nozzle portion, and a
pressure increasing portion for mixing refrigerant drawn through
the refrigerant suction port with the high-speed refrigerant flow
and for decelerating the mixed refrigerant flow to raise a pressure
of the refrigerant flow; a first evaporator that evaporates
refrigerant flowing out of the ejector; a branch passage that is
branched from a branch portion between the radiator and the ejector
and is coupled to the refrigerant suction port, for guiding
refrigerant from the radiator into the refrigerant suction port; a
throttling unit that is located in the branch passage and
depressurizes refrigerant to adjust a flow rate of refrigerant; a
second evaporator that is located downstream of the throttling unit
and evaporates refrigerant; and a blower unit disposed to blow air
to at least one of the first evaporator and the second evaporator,
wherein the blower unit includes an air blowing adjusting means for
adjusting an air blowing amount of the blower unit, and wherein the
air blowing adjusting means adjusts the air amount of the blower
unit, based on at least a physical quantity related to at least one
of a state of refrigerant in the refrigerant cycle, a temperature
of a space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be
cooled.
14. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a radiator that radiates heat from
high-pressure refrigerant discharged from the compressor; an
ejector disposed downstream of the radiator, the ejector having a
nozzle portion for depressurizing and expanding refrigerant, a
refrigerant suction port through which refrigerant is drawn by a
high-speed refrigerant flow jetted from the nozzle portion, and a
pressure increasing portion for mixing refrigerant drawn through
the refrigerant suction port with the high-speed refrigerant flow
and for decelerating the mixed refrigerant flow to raise a pressure
of the refrigerant flow; a first evaporator that evaporates
refrigerant flowing out of the ejector; a branch passage that is
branched from a branch portion between the radiator and the ejector
and is coupled to the refrigerant suction port, for guiding
refrigerant from the radiator into the refrigerant suction port; a
throttling unit that is located in the branch passage and
depressurizes refrigerant to adjust a flow rate of refrigerant; a
second evaporator that is located downstream of the throttling unit
and evaporates refrigerant; a blower unit disposed to blow air to
the radiator; and an air blowing adjusting means for adjusting an
air blowing amount of the blower unit, wherein the air blowing
adjusting means adjusts the air blowing amount of the blower unit,
based on at least a physical quantity related to at least one of a
state of refrigerant in the refrigerant cycle, a temperature of a
space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be
cooled.
15. The ejector cycle system according to claim 1, wherein the
physical quantity is related to a superheat degree of refrigerant
at a refrigerant outlet side of the first evaporator.
16. The ejector cycle system according to claim 1, wherein the
physical quantity is related to a superheat degree of refrigerant
at a refrigerant outlet side of the second evaporator.
17. The ejector cycle system according to claim 1, wherein the
physical quantity is related to a supercool degree of refrigerant
at a refrigerant outlet side of the radiator.
18. The ejector cycle system according to claim 1, wherein the
high-pressure refrigerant has a pressure higher than a critical
pressure of the refrigerant, and wherein the physical quantity is
related to a temperature and a pressure of refrigerant at a
refrigerant outlet side of the radiator.
19. The ejector cycle system according to claim 1, wherein the
physical quantity is related to the flow ratio.
20. The ejector cycle system according to claim 1, wherein the
physical quantity is related to a flow amount of refrigerant
discharged from the compressor.
21. The ejector cycle system according to claim 1, further
comprising an accumulator located downstream of the first
evaporator to separate refrigerant into gas phase refrigerant and
liquid phase refrigerant.
22. The ejector cycle system according to claim 8, further
comprising an accumulator located downstream of the first
evaporator to separate refrigerant into gas phase refrigerant and
liquid phase refrigerant.
23. The ejector cycle system according to claim 10, further
comprising an accumulator located downstream of the first
evaporator to separate refrigerant into gas phase refrigerant and
liquid phase refrigerant.
24. The ejector cycle system according to claim 13, further
comprising an accumulator located downstream of the first
evaporator to separate refrigerant into gas phase refrigerant and
liquid phase refrigerant.
25. The ejector cycle system according to claim 14, further
comprising an accumulator located downstream of the first
evaporator to separate refrigerant into gas phase refrigerant and
liquid phase refrigerant.
26. An ejector cycle system with a refrigerant cycle through which
refrigerant flows, comprising: a compressor that draws and
compresses refrigerant; a radiator that radiates heat from
high-pressure refrigerant discharged from the compressor; an
ejector disposed downstream of the radiator, the ejector having a
nozzle portion for depressurizing and expanding refrigerant, a
refrigerant suction port through which refrigerant is drawn by a
high-speed refrigerant flow jetted from the nozzle portion, and a
pressure increasing portion for mixing refrigerant drawn through
the refrigerant suction port with the high-speed refrigerant flow
and for decelerating the mixed refrigerant flow to raise a pressure
of the refrigerant flow; a first evaporator that evaporates
refrigerant flowing out of the ejector; a branch passage that is
branched from a branch portion between the radiator and the ejector
and is coupled to the refrigerant suction port, for guiding
refrigerant from the radiator into the refrigerant suction port; a
throttling unit that is located in the branch passage and
depressurizes refrigerant to adjust a flow rate of refrigerant; a
second evaporator that is located downstream of the throttling unit
and evaporates refrigerant; a determining means for determining
whether a rapid cooling is necessary for a space to be cooled by
the first evaporator and the second evaporator; and an adjusting
means for adjusting an evaporation temperature of at least one of
the first evaporator and the second evaporator, wherein the
adjusting means reduces the evaporation temperature of at least one
of the first evaporator and the second evaporator when the
determining means determines that the rapid cooling is
necessary.
27. The ejector cycle system according to claim 26, further
comprising an input means capable of inputting a rapid cooling
request by a user, wherein the determining means determines that
the rapid cooling is necessary when the rapid cooling request is
input through the input means.
28. The ejector cycle system according to claim 26, wherein the
determining means determines a rapid cooling, based on at least a
physical quantity related to at least one of a state of refrigerant
in the refrigerant cycle, a temperature of a space to be cooled by
the first evaporator and the second evaporator, and an ambient
temperature of the space to be cooled.
29. The ejector cycle system according to claim 26, further
comprising a flow ratio adjusting means which adjusts a flow ratio
between a first refrigerant flow amount depressurized and expanded
in the nozzle portion of the ejector and a second refrigerant flow
amount drawn into the refrigerant suction port, wherein the flow
ratio adjusting means shuts a refrigerant flow depressurized and
expanded in the nozzle portion of the ejector so as to reduce the
evaporation temperature, when the determining means determines that
the rapid cooling is necessary.
30. The ejector cycle system according to claim 29, further
comprising a variable throttling member located between the branch
portion and the nozzle portion of the ejector, wherein the flow
ratio adjusting means is constructed of the throttling unit
itself.
31. The ejector cycle system according to claim 29, wherein the
flow ratio adjusting means is constructed of the ejector
itself.
32. The ejector cycle system according to claim 26, further
comprising a discharge capacity varying section that adjusts a flow
amount of refrigerant discharged from the compressor, wherein the
discharge capacity varying section increases the flow amount of
refrigerant discharged from the compressor so as to reduce the
evaporation temperature when the determining means determines that
the rapid cooling is necessary.
33. The ejector cycle system according to claim 26, further
comprising: a blower unit for blowing air to at least the second
evaporator; and a blower adjusting unit which adjusts an air
blowing amount of the blower unit, wherein the blower adjusting
unit reduces the air blowing amount so as to decrease the
evaporation temperature when the determining means determines that
the rapid cooling is necessary.
34. The ejector cycle system according to claim 26, further
comprising an increasing means which increases a superheat degree
of refrigerant at an outlet side of at least one of the first
evaporator and the second evaporator, wherein the increasing means
increases the superheat degree so as to decrease the evaporation
temperature when the determining means determines that the rapid
cooling is necessary.
35. An ejector cycle system comprising: a compressor for
compressing refrigerant; a condenser for cooling and condensing
refrigerant compressed by the compressor; an ejector provided
downstream of the condenser, wherein the ejector has a nozzle
portion having a refrigerant inlet port, for decompressing
refrigerant from the condenser, a refrigerant suction port through
which refrigerant is drawn by refrigerant passing through the
nozzle portion of the ejector, and a refrigerant outlet port for
discharging refrigerant from the ejector; an evaporator that is
disposed to exchange heat between an external fluid and refrigerant
branched and introduced from an upstream side of the ejector, and
has a refrigerant outlet connected to the refrigerant suction port
of the ejector; a detection means that detects a controllable
factor for determining a staying state of oil in the evaporator; a
determining means that determines whether oil is staying in the
evaporator based on an information from the detection means; and an
oil flow-down means that causes the oil to flow down, when the
determining means determines that oil is staying in the
evaporator.
36. The ejector cycle system according to claim 35, wherein the oil
flow-down means increases a flow rate of refrigerant flowing in the
evaporator when the controllable factor is not in a predetermined
range.
37. The ejector cycle system according to claim 35, wherein a state
of superheated refrigerant gas (SH) on a refrigerant outlet side of
the evaporator is used as the controllable factor.
38. The ejector cycle system according to claim 35, wherein a
refrigerant temperature difference between refrigerant outlet and
inlet of the evaporator or a refrigerant pressure loss between the
refrigerant outlet and inlet of the evaporator is used as the
controllable factor.
39. The ejector cycle system according to claim 35, wherein a
pressure difference between the refrigerant suction port and the
refrigerant outlet port of the ejector is used as the controllable
factor.
40. The ejector cycle system according to claim 35, further
comprising: a flow control device that is provided downstream of
the condenser and adjusts the flow rate of refrigerant flowing to
the ejector and a flow rate of refrigerant flowing to the
evaporator, wherein the flow control device is provided with a
variable expansion valve placed upstream of the refrigerant inlet
port of the ejector.
41. The ejector cycle system according to claim 40, wherein the oil
flow-down means is provided with a controlling means that makes
adjustment so as to reduce an opening of the variable expansion
valve or the nozzle portion of the ejector when the controllable
factor is not in a predetermined range.
42. The ejector cycle system according to claim 35, wherein the oil
flow-down means temporarily stops the compressor when the
controllable factor is not in a predetermined range.
43. The ejector cycle system according to claim 35, wherein, when
the controllable factor is not in a predetermined range, the oil
flow-down means hinders a refrigerant cooling in the condenser or
increases a load on the fluid medium that exchanges heat with
refrigerant in the condenser.
44. The ejector cycle system according to claim 35, further
comprising: an another evaporator connected with the outlet port of
the ejector.
45. The ejector cycle system according to claim 35, wherein Freon
refrigerant, hydrocarbon refrigerant, or carbon dioxide is used as
the refrigerant.
46. An operation method for an ejector cycle system, comprising:
passing refrigerant through an ejector and passing refrigerant
through an evaporator by a suction force of the ejector; detecting
a controllable factor for determining a staying of oil in the
evaporator during the passing; and causing oil to flow down from
the evaporator when the controllable factor is not in a
predetermined range.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Applications
No. 2005-191156 filed on Jun. 30, 2005, No. 2005-233169 filed on
Aug. 11, 2005, and No. 2005-237651 filed on Aug. 18, 2005, the
contents of which are incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an ejector cycle system
having an ejector that functions as a refrigerant pressure reducing
means and a refrigerant circulating means.
BACKGROUND OF THE INVENTION
[0003] Ejector cycle systems provided with multiple evaporators
have been conventionally known as in JP Patent No. 3322263
(corresponding to U.S. Pat. No. 6,574,987, U.S. Pat. No.
6,477,857).
[0004] As illustrated in FIG. 26, a first evaporator 16 is
connected downstream of an ejector 15 with respect to a refrigerant
flow. An accumulator 32 that forms a vapor-liquid separator is
located downstream of the first evaporator 16 with respect to the
refrigerant flow. Further, a second evaporator 20 is located
between a liquid phase refrigerant outlet of the accumulator 32 and
a refrigerant suction port 15b of the ejector 15. The two
evaporators 16, 20 are simultaneously operated.
[0005] In this refrigerant cycle, a pressure drop caused by a
high-speed flow of refrigerant as expanded is utilized to draw
refrigerant that flows out of the second evaporator 20, and
further, velocity energy of refrigerant as expanded is converted
into pressure energy at a diffuser portion 15d (pressure increasing
portion) to raise the refrigerant pressure (i.e., the inlet
pressure of a compressor 11). Thus, power for driving the
compressor 11 can be reduced, and the efficiency of cycle operation
can be enhanced.
[0006] In this refrigerant cycle, heat absorbing (cooling) action
can be produced from separate spaces by using the first evaporator
16 and the second evaporator 20, or it can be produced from one and
the same space by the two evaporators 16, 20. Also, the interior of
a vehicle compartment can be cooled by using the two evaporators
16, 20.
[0007] In this refrigerant cycle, refrigerant that flows out of a
radiator 12 all passes through a nozzle portion 15a of the ejector
15. Here, the flow rate of refrigerant that passes through the
nozzle portion 15a of the ejector 15 is referred to as Gnoz. This
Gnoz is set to such a flow rate that the dryness of refrigerant on
the outlet side of the first evaporator 16 becomes a predetermined
value or below. The refrigerant depressurized through the nozzle
portion 15a is mixed with the refrigerant drawn through the
refrigerant suction port 15b of the ejector 15, and flows into the
first evaporator 16. The refrigerant that flows out of the first
evaporator 16 is separated into vapor phase refrigerant and liquid
phase refrigerant in the accumulator 32.
[0008] The refrigerant suction port 15b of the ejector 15 is
depressurized and thus produces sucking action. As a result, the
second evaporator 20 is supplied with the liquid phase refrigerant
separated in the accumulator 32. Here, the flow rate of refrigerant
drawn through the refrigerant suction port 15b is referred to as
Ge. The liquid phase refrigerant that flows into the second
evaporator 20 is evaporated at the second evaporator 20. Therefore,
most or all of the refrigerant drawn through the refrigerant
suction port 15b is vapor phase refrigerant. Consequently, the flow
rate Gnoz of liquid phase refrigerant substantially contributes to
the cooling capacity of the first evaporator 16. Therefore, the
cooling capacity of the first evaporator 16 is influenced by
Gnoz.
[0009] By increasing the flow rate Ge of refrigerant drawn to the
refrigerant suction port 15b of the ejector 15, the flow rate of
liquid phase refrigerant that flows into the second evaporator 20
is increased. Accordingly, the cooling capacity of the second
evaporator 20 can be increased without reducing the cooling
capacity of the first evaporator 16, and thus the cooling capacity
of the entire cycle is increased as well.
[0010] The cooling capacity of an evaporator is defined, for
example, as increment in the enthalpy of refrigerant observed when
the refrigerant absorbs heat from air in the evaporator. The
increment in enthalpy is defined by multiplying an increment in the
specific enthalpy of refrigerant per unit weight by the flow rate
of the refrigerant. The cooling capacity of the entire cycle is
defined as the sum Qer of increments in the enthalpy of refrigerant
at the first and second evaporators 16 and 20. The cooling capacity
may also be defined as the coefficient of performance (COP)
obtained by dividing Qer by the power consumed by the compressor
11.
[0011] In a conventional cycle, therefore, the phenomenon
illustrated in FIG. 28 takes place. That is, when the flow ratio
.eta. (.eta.=Ge/Gnoz) is increased, the cooling capacity Qer of the
entire cycle is increased as well. The flow ratio .eta. is the
ratio of the flow rate Ge of refrigerant drawn into the refrigerant
suction port 15b of the ejector 15 to the flow rate Gnoz of
refrigerant that passes through the nozzle portion 15a of the
ejector 15.
[0012] When the heat load of the conventional is low, the
difference between the high pressure and the low pressure of
refrigerant in the cycle is reduced; therefore, the input to the
ejector 15 is reduced. In this case, a problem arises in the
conventional cycle. Since the refrigerant flow rate Ge depends only
on the refrigerant sucking capability of the ejector 15, the
following takes placed: reduction in the input to the ejector
15.fwdarw.reduction in the refrigerant sucking capability of the
ejector 15.fwdarw.reduction in the flow rate of liquid phase
refrigerant that flows into the second evaporator
20.fwdarw.reduction in flow ratio .eta.. This results in reduction
in cooling capacity Qer.
[0013] The US 2005/0178150 proposes an ejector cycle (comparison
cycle in FIG. 28) illustrated in FIG. 27. In this ejector cycle of
FIG. 27, a branch passage 18 is provided between the discharge side
of a radiator 12 and the refrigerant inflow port of an ejector 15.
A throttling mechanism 42 that adjusts the pressure and flow rate
of refrigerant and a second evaporator 20 are located in this
branch passage 18. The outlet of the second evaporator 20 is
connected to the refrigerant suction port 15b of the ejector
15.
[0014] The flow of refrigerant is separated upstream of the ejector
15, and the separated refrigerant is drawn into the refrigerant
suction port 15b through the branch passage 18. Therefore, the
branch passage 18 is in parallel relation with the ejector 15 with
respect to connection. For this reason, when refrigerant is
supplied to the branch passage 18, the refrigerant sucking and
discharging capability of the compressor 11 can be utilized in
addition to the refrigerant sucking capability of the ejector
15.
[0015] Therefore, even though the phenomenon of reduction in the
input to the ejector 15 and reduction in the refrigerant sucking
capability of the ejector 15 occurs, the degree of reduction in the
flow rate Ge of refrigerant drawn into the refrigerant suction port
15b of the ejector 15 can be reduced more than in the conventional
cycle.
[0016] In the ejector cycle proposed in the US 2005/0178150, the
flow of refrigerant is separated upstream of the ejector 15.
Therefore, the flow rate Gn of refrigerant that flows out of the
radiator 12 is equal to the sum of the flow rate Gnoz of
refrigerant that passes through the nozzle portion 15a of the
ejector 15 and the flow rate of refrigerant that flows into the
second evaporator 20. The flow rate of refrigerant that flows into
the second evaporator 20 is equal to the flow rate Ge of
refrigerant drawn into the refrigerant suction port 15b of the
ejector 15.
[0017] Therefore, the relation expressed as Gn=Gnoz+Ge can be
maintained. Thus, when Gnoz is reduced, Ge is increased; when Gnoz
is conversely increased, Ge is reduced. Therefore, even when the
cooling capacity of the first evaporator 16 is lowered, the cooling
capacity of the second evaporator 20 is increased; even when the
cooling capacity of the second evaporator 20 is conversely reduced,
the cooling capacity of the first evaporator 16 is increased.
Hence, the cooling capacity Qer of the comparison cycle illustrated
in FIG. 28 is brought. That is, in the comparison cycle, a change
in cooling capacity Qer for a change in flow ratio n is smaller
than that in the conventional cycle, and the cooling capacity is
peaked at the optimum flow ratio .eta.max.
[0018] Furthermore, in an ejector cycle system where refrigerant is
circulated in a refrigerant cycle using a suction force of an
ejector, oil is easily stayed in an evaporator based on an
operation state of the ejector. Generally, a predetermined oil
circulating amount is necessary when the system is operated under a
low load for a long time in order to protect a compressor.
SUMMARY OF THE INVENTION
[0019] In view of the foregoing problems, it is required to make
the flow ratio .eta. close to the optimum flow ratio .eta.max in
the cycle in order to operate an ejector cycle system with high
cooling capacity Qer. Furthermore, it is also required to return
oil to the compressor in a refrigerant cycle system.
[0020] It is an object of the present invention to operate an
ejector cycle system with high cooling capacity in the whole
refrigerant cycle.
[0021] It is another object of the present invention to provide an
ejector cycle system, which can effectively return oil into a
compressor.
[0022] It is further another object of the present invention to
provide an ejector cycle system in which oil staying in an
evaporator can be effectively restricted by flowing out refrigerant
from an evaporator based on an operation state of the
evaporator.
[0023] According to an aspect of the present invention, an ejector
cycle system with a refrigerant cycle through which refrigerant
flows includes: a compressor that draws and compresses refrigerant;
a radiator that radiates heat from high-pressure refrigerant
discharged from the compressor; an ejector disposed downstream of
the radiator, the ejector having a nozzle portion for
depressurizing and expanding refrigerant, a refrigerant suction
port through which refrigerant is drawn by a high-speed refrigerant
flow jetted from the nozzle portion, and a pressure increasing
portion for mixing refrigerant drawn through the refrigerant
suction port with the high-speed refrigerant flow and for
decelerating the mixed refrigerant flow to raise a pressure of the
refrigerant flow; a first evaporator that evaporates refrigerant
flowing out of the ejector; a branch passage that is branched from
a branch portion between the radiator and the ejector and is
coupled to the refrigerant suction port, for guiding refrigerant
from the radiator into the refrigerant suction port; a throttling
unit that is located in the branch passage and depressurizes
refrigerant to adjust a flow rate of refrigerant; and a second
evaporator that is located downstream of the throttling unit and
evaporates refrigerant.
[0024] In this refrigerant cycle system, a flow ratio adjusting
means adjusts a flow ratio between a first refrigerant flow amount
depressurized and expanded in the nozzle portion of the ejector and
a second refrigerant flow amount drawn into the refrigerant suction
port, based on at least a physical quantity related to at least one
of a state of refrigerant in the refrigerant cycle, a temperature
of a space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be cooled.
Accordingly, the whole refrigerant cycle can be operated with a
high cooling capacity. For example, the flow ratio adjusting means
is constructed of the ejector itself, or the flow ratio adjusting
means is constructed of the throttling unit itself, or the flow
ratio adjusting ratio is constructed of a variable throttling
member that is different from the ejector and the throttling unit.
Furthermore, the variable throttling member can be located between
the branch portion of the branch passage and a refrigerant inflow
port of the nozzle portion of the ejector, or the throttling unit
may be a variable throttle member located between the branch
portion of the branch passage and a refrigerant inflow port of the
second evaporator, or the variable throttling member is located at
the branch portion of the branch passage.
[0025] According to another aspect of the present invention, in an
ejector cycle system, a flow amount adjusting means is provided to
adjust a flow amount in the whole refrigerant cycle, based on at
least a physical quantity related to at least one of a state of
refrigerant in the refrigerant cycle, a temperature of a space to
be cooled by the first evaporator and the second evaporator, and an
ambient temperature of the space to be cooled. In this case, a high
cooling capacity can be obtained in the whole refrigerant cycle of
the ejector cycle system. For example, the flow amount adjusting
means may be located upstream of the branch portion of the branch
passage.
[0026] According to a further another aspect of the present
invention, a discharge capacity varying section can be provided to
adjust a flow amount of refrigerant discharged from a compressor in
a refrigerant cycle system. In this case, the discharge capacity
varying means adjusts the flow amount of refrigerant discharged
from the compressor, based on at least a physical quantity related
to at least one of a state of refrigerant in the refrigerant cycle,
a temperature of a space to be cooled by the first evaporator and
the second evaporator, and an ambient temperature of the space to
be cooled. Even in this case, the ejector cycle system can be
operated while having a high cooling capacity in the whole
refrigerant cycle. For example, the compressor may be a
displacement variable compressor. In this case, the discharge
capacity varying section may be an electrical capacity control
valve which adjusts the flow amount of the refrigerant discharged
from the compressor by changing a discharge capacity of the
compressor. Alternatively, the discharge capacity varying section
may be an electromagnetic clutch which adjusts the flow amount of
the refrigerant discharged from the compressor by changing a ratio
between an operation state and a non-operation state of the
compressor.
[0027] According to a further another aspect of the present
invention, in an ejector cycle system, a blower unit is disposed to
blow air to at least one of the first evaporator and the second
evaporator, and the blower unit includes an air blowing adjusting
means for adjusting an air blowing amount of the blower unit. In
this case, the air blowing adjusting means adjusts the air amount
of the blower unit, based on at least a physical quantity related
to at least one of a state of refrigerant in the refrigerant cycle,
a temperature of a space to be cooled by the first evaporator and
the second evaporator, and an ambient temperature of the space to
be cooled. Alternatively, a blower unit may be disposed to blow air
to the radiator, and an air blowing adjusting means for adjusting
an air blowing amount of the blower unit. Further, the air blowing
adjusting means adjusts the air blowing amount of the blower unit,
based on at least a physical quantity related to at least one of a
state of refrigerant in the refrigerant cycle, a temperature of a
space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be cooled.
Accordingly, it is possible to adjust a refrigerant flow amount in
a refrigerant cycle, and a high cooling capacity can be obtained in
the entire refrigerant cycle.
[0028] In any refrigerant cycle system, the physical quantity may
be related to a superheat degree of refrigerant at a refrigerant
outlet side of the first evaporator, may be related to a superheat
degree of refrigerant at a refrigerant outlet side of the second
evaporator, or may be related to a supercool degree of refrigerant
at a refrigerant outlet side of the radiator. Furthermore, the
physical quantity may be related to a temperature and a pressure of
refrigerant at a refrigerant outlet side of the radiator, or may be
related to the flow ratio, or may be related to a flow amount of
refrigerant discharged from the compressor. Furthermore, an
accumulator may be located downstream of the first evaporator to
separate refrigerant into gas phase refrigerant and liquid phase
refrigerant.
[0029] According to a further another aspect of the present
invention, an ejector cycle system is provided with a determining
means for determining whether a rapid cooling is necessary for a
space to be cooled by the first evaporator and the second
evaporator, and an adjusting means for adjusting an evaporation
temperature of at least one of the first evaporator and the second
evaporator. In this case, the adjusting means reduces the
evaporation temperature of at least one of the first evaporator and
the second evaporator when the determining means determines that
the rapid cooling is necessary. Accordingly, a rapid cooling for
the space to be cooled can be easily performed.
[0030] For example, an input means capable of inputting a rapid
cooling request by a user may be provided. In this case, the
determining means determines that the rapid cooling is necessary
when the rapid cooling request is input through the input means.
Alternatively, the determining means may determine a rapid cooling,
based on at least a physical quantity related to at least one of a
state of refrigerant in the refrigerant cycle, a temperature of a
space to be cooled by the first evaporator and the second
evaporator, and an ambient temperature of the space to be cooled.
Alternatively, a flow ratio adjusting means may be provided to
adjust a flow ratio between a first refrigerant flow amount
depressurized and expanded in the nozzle portion of the ejector and
a second refrigerant flow amount drawn into the refrigerant suction
port. In this case, the flow ratio adjusting means shuts a
refrigerant flow depressurized and expanded in the nozzle portion
of the ejector so as to reduce the evaporation temperature, when
the determining means determines that the rapid cooling is
necessary. Alternatively, a variable throttling member may be
located between the branch portion and the nozzle portion of the
ejector. In this case, the flow ratio adjusting means is
constructed of the throttling unit itself. For example, the flow
ratio adjusting means may be constructed of the ejector itself.
Alternatively, a discharge capacity varying section may be provided
to adjust a flow amount of refrigerant discharged from the
compressor. In this case, the discharge capacity varying section
increases the flow amount of refrigerant discharged from the
compressor so as to reduce the evaporation temperature when the
determining means determines that the rapid cooling is
necessary.
[0031] Alternatively, the ejector cycle system may be provided with
a blower unit for blowing air to at least the second evaporator and
a blower adjusting unit which adjusts an air blowing amount of the
blower unit. In this case, the blower adjusting unit reduces the
air blowing amount so as to decrease the evaporation temperature
when the determining means determines that the rapid cooling is
necessary. Alternatively, an increasing means may be provided to
increase a superheat degree of refrigerant at an outlet side of at
least one of the first evaporator and the second evaporator. In
this case, the increasing means increases the superheat degree so
as to decrease the evaporation temperature when the determining
means determines that the rapid cooling is necessary.
[0032] According to a further another aspect of the present
invention, an ejector cycle system includes: a compressor for
compressing refrigerant; a condenser for cooling and condensing
refrigerant compressed by the compressor; an ejector provided
downstream of the condenser, wherein the ejector has a nozzle
portion having a refrigerant inlet port, for decompressing
refrigerant from the condenser, a refrigerant suction port through
which refrigerant is drawn by refrigerant passing through the
nozzle portion of the ejector, and a refrigerant outlet port for
discharging refrigerant from the ejector; an evaporator that is
disposed to exchange heat between an external fluid and refrigerant
branched and introduced from an upstream side of the ejector, and
has a refrigerant outlet connected to the refrigerant suction port
of the ejector; a detection means that detects a controllable
factor for determining a staying state of oil in the evaporator; a
determining means that determines whether oil is staying in the
evaporator based on an information from the detection means; and an
oil flow-down means that causes the oil to flow down, when the
determining means determines that oil is staying in the evaporator.
Accordingly, it can prevent oil from staying in the evaporator, and
the compressor can be effectively protected.
[0033] For example, the oil flow-down means may increase a flow
rate of refrigerant flowing in the evaporator when the controllable
factor is not in a predetermined range. Furthermore, a state of
superheated refrigerant gas (SH) on a refrigerant outlet side of
the evaporator may be used as the controllable factor, or a
refrigerant temperature difference between refrigerant outlet and
inlet of the evaporator or a refrigerant pressure loss between the
refrigerant outlet and inlet of the evaporator may be used as the
controllable factor, or a pressure difference between the
refrigerant suction port and the refrigerant outlet port of the
ejector may be used as the controllable factor.
[0034] Alternatively, a flow control device may be provided
downstream of the condenser and may adjust the flow rate of
refrigerant flowing to the ejector and a flow rate of refrigerant
flowing to the evaporator. In this case, the flow control device
can be provided with a variable expansion valve placed upstream of
the refrigerant inlet port of the ejector. Furthermore, the oil
flow-down means can be provided with a controlling means that makes
adjustment so as to reduce an opening of the variable expansion
valve or the nozzle portion of the ejector when the controllable
factor is not in a predetermined range.
[0035] Alternatively, the oil flow-down means temporarily may stop
the compressor when the controllable factor is not in a
predetermined range. Alternatively, when the controllable factor is
not in a predetermined range, the oil flow-down means may hinder a
refrigerant cooling in the condenser or increase a load on the
fluid medium that exchanges heat with refrigerant in the
condenser.
[0036] Furthermore, an another evaporator may be connected with the
outlet port of the ejector. In addition, freon refrigerant,
hydrocarbon refrigerant, or carbon dioxide may be used as the
refrigerant.
[0037] According to a further another aspect of the present
invention, an operation method for an ejector cycle system
includes: passing refrigerant through an ejector and passing
refrigerant through an evaporator by a suction force of the
ejector; detecting a controllable factor for determining a staying
of oil in the evaporator during the passing step; and causing oil
to flow down from the evaporator when the controllable factor is
not in a predetermined range. Accordingly, it can restrict oil from
staying in the evaporator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] Additional objects and advantages of the present invention
will be more readily apparent from the following detailed
description of preferred embodiments when taken together with the
accompanying drawings, in which:
[0039] FIG. 1 is a schematic diagram showing an ejector cycle
system according to a first embodiment of the present
invention;
[0040] FIG. 2 is a schematic diagram showing an ejector cycle
system according to a second embodiment of the present
invention;
[0041] FIG. 3 is a schematic diagram showing an ejector cycle
system according to a third embodiment of the present
invention;
[0042] FIG. 4 is a schematic diagram showing an ejector cycle
system according to a first embodiment of the present
invention;
[0043] FIG. 5 is a schematic diagram showing an ejector cycle
system according to a fifth embodiment of the present
invention;
[0044] FIG. 6 is a schematic diagram showing an ejector cycle
system according to a sixth embodiment of the present
invention;
[0045] FIG. 7 is a schematic diagram showing an ejector cycle
system according to a seventh embodiment of the present
invention;
[0046] FIG. 8 is a schematic diagram showing an ejector cycle
system according to an eighth embodiment of the present
invention;
[0047] FIG. 9 is a schematic diagram showing an ejector cycle
system according to a ninth embodiment of the present
invention;
[0048] FIG. 10 is a schematic diagram showing an ejector cycle
system according to a 10th embodiment of the present invention;
[0049] FIG. 11 is a schematic diagram showing an ejector cycle
system according to an 11th embodiment of the present
invention;
[0050] FIG. 12 is a schematic diagram showing an ejector cycle
system according to a 12th embodiment of the present invention;
[0051] FIG. 13 is a schematic diagram showing an ejector cycle
system according to a 13th embodiment of the present invention;
[0052] FIG. 14 is a schematic diagram showing an ejector cycle
system according to a 14th embodiment of the present invention;
[0053] FIG. 15 is a schematic diagram showing an ejector cycle
system according to a 15th embodiment of the present invention;
[0054] FIG. 16 is a schematic diagram showing an ejector cycle
system according to a 16th embodiment of the present invention;
[0055] FIG. 17 is a schematic diagram showing an ejector cycle
system according to a 17th embodiment of the present invention;
[0056] FIG. 18 is a schematic diagram showing an ejector cycle
system according to a 18th embodiment of the present invention;
[0057] FIG. 19 is a schematic diagram showing an ejector cycle
system according to a 19th embodiment of the present invention;
[0058] FIG. 20 is a schematic diagram showing an ejector cycle
system according to 20th-22nd embodiments of the present
invention;
[0059] FIG. 21 is a schematic diagram showing an ejector cycle
system according to a 23rd embodiment of the present invention;
[0060] FIG. 22 is a schematic diagram showing an ejector cycle
system according to a 24th embodiment of the present invention;
[0061] FIG. 23 is a flow diagram showing control operation of the
ejector cycle system according to 24th-26th embodiments of the
present invention;
[0062] FIG. 24 is a schematic diagram showing an ejector cycle
system according to the 25th embodiment of the present
invention;
[0063] FIG. 25 is a schematic diagram showing an ejector cycle
system according to the 26th embodiment of the present
invention;
[0064] FIG. 26 is a schematic diagram showing an ejector cycle
system according to a conventional example;
[0065] FIG. 27 is a schematic diagram showing an ejector cycle
system according to a comparison example of the present
invention;
[0066] FIG. 28 is a graph showing a relationship between a cooling
capacity and a flow ratio in the cycles of FIGS. 26 and 27;
[0067] FIG. 29 is a system diagram showing a refrigeration cycle
and a controller (ECU) of an another embodiment; and
[0068] FIG. 30 is a block diagram showing functional blocks and
signal flows provided by the controller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0069] FIG. 1 illustrates an example in which an ejector cycle
system 10 of the first embodiment is applied to a refrigerator
device for vehicles. The refrigerator device for vehicles in this
embodiment is so constructed as to lower the temperature inside a
compartment to a very low temperature close to -20.degree. C., for
example.
[0070] In the ejector cycle system 10, a compressor 11 sucks in,
compresses, and discharges refrigerant. The compressor 11 is
rotationally driven by an engine for vehicle running (not shown)
through an electromagnetic clutch 11a and a belt. This embodiment
uses a swash plate-type variable displacement compressor whose
discharge capacity can be continuously and variably controlled by
external control signals.
[0071] More specific description will be given. The pressure in a
swash plate chamber (not shown) is controlled utilizing the
discharge pressure and the inlet pressure of the compressor 11.
Thus, the angle of inclination of the swash plate is varied to
change the piston stroke, and the discharge capacity is thereby
continuously changed within the range from substantially 0% to
100%. Refrigerant discharge capability can be adjusted through this
change in discharge capacity.
[0072] The discharge capacity is the geometric volume of an
operating space in which refrigerant is drawn and compressed, and
is equivalent to the cylinder capacity between the top dead center
and the bottom dead center of a piston stroke.
[0073] Description will be given to the control of the pressure in
the swash plate chamber. The compressor 11 is provided with an
electromagnetic capacity control valve 11b. This electromagnetic
capacity control valve 11b incorporates: a pressure response
mechanism (not shown) that produces force F1 arising from the low
refrigerant pressure on the suction side of the compressor 11; and
an electromagnetic mechanism (not shown) that produces
electromagnetic force F2 that counters this force F1 arising from
the low refrigerant pressure Ps.
[0074] The electromagnetic force F2 of the electromagnetic
mechanism is determined by control current In outputted from an air
conditioning controller 21 described later. The pressure in the
swash plate chamber is varied by changing the ratio of
high-pressure refrigerant to low-pressure refrigerant introduced
into the swash plate chamber by a valve body (not shown) that is
displaced in correspondence with the force F1 corresponding to the
low refrigerant pressure Ps and the electromagnetic force F2.
[0075] The discharge capacity of the compressor 11 can be
continuously varied over the range from 100% to substantially 0% by
the adjustment of the pressure in the swash plate chamber.
Therefore, the compressor 11 can be brought substantially into
operation stop state by reducing the discharge capacity to
substantially 0%. Consequently, the compressor 11 may be
constructed as a clutch-less compressor in which its rotating shaft
is constantly coupled with a vehicle engine through a pulley and a
belt V.
[0076] A radiator 12 is connected to the refrigerant discharge side
of the compressor 11. The radiator 12 is a heat exchanger that
exchanges heat between the high-pressure refrigerant discharged
from the compressor 11 and the outside air (i.e., air outside the
vehicle compartment) sent by a blower 12a for radiator to cool the
high-pressure refrigerant.
[0077] The blower 12a for radiator is driven by an electric motor
12b for driving. The electric motor 12b for driving is so
constructed that it is rotationally driven when applied voltage V1
is outputted from the air conditioning controller 21. Therefore,
since the number of revolutions of the electric motor 12b for
driving can be varied by the air conditioning controller 21 (A/C
ECU) by varying the applied voltage V1, the quantity of air sent by
the blower 12a for radiator 12 can be varied.
[0078] This embodiment uses ordinary fluorocarbon refrigerant as
the refrigerant circulating in the cycle. Therefore, the ejector
cycle system 10 constructs a subcritical cycle in which a high
pressure does not exceed a critical pressure. Therefore, the
radiator 12 functions as a condenser that cools and condenses
refrigerant.
[0079] A liquid receiver 13 as a vapor-liquid separator that
separates refrigerant into vapor and liquid and stores the liquid
phase refrigerant is located downstream of the radiator 12 with
respect to a refrigerant flow. Liquid phase refrigerant is guided
out of this liquid receiver 13 to the downstream side. A variable
throttling mechanism 14 is connected downstream of the liquid
receiver 13 with respect to refrigerant flow.
[0080] Specifically, this variable throttling mechanism 14 is a
generally known thermal expansion valve. The variable throttling
mechanism 14 functions to depressurize the high-pressure liquid
phase refrigerant from the liquid receiver 13 into
intermediate-pressure refrigerant with the vapor and liquid two
phases.
[0081] This thermal expansion valve adjusts the opening of a valve
body portion (not shown) according to the degree of superheat of
the refrigerant on the outlet side of a first evaporator 16
described later. Accordingly, the flow rate of refrigerant that
passes through the variable throttling mechanism 14 can be
adjusted, so that the degree of superheat of refrigerant on the
outlet side of the first evaporator 16 approaches a predetermined
value. That is, in this embodiment, the valve body portion of the
thermal expansion valve makes a means for adjusting the flow ratio
(.eta.).
[0082] The valve body of the thermal expansion valve is coupled
with a diaphragm mechanism 14a that forms a pressure responding
means. The diaphragm mechanism 14a adjusts the opening of the valve
body by displacing the valve body according to the following: the
pressure of a filler gas medium in a temperature sensitive cylinder
14b (the pressure corresponding to the temperature of refrigerant
on the outlet side of the first evaporator 16); and the pressure of
refrigerant on the outlet side of the first evaporator 16,
introduced through an equalizing pipe 14c. That is, in this
embodiment, the temperature sensitive cylinder 14b and the
equalizing pipe 14c make a means for detecting the physical
quantities related to the state of refrigerant in the cycle.
[0083] An ejector 15 is connected with the outlet of the variable
throttling mechanism 14. This ejector 15 is a pressure reducing
unit for depressurizing refrigerant and is also a refrigerant
circulating means for circulating refrigerant by the sucking action
(engulfing action) of a refrigerant flow jetting out at high
speed.
[0084] The ejector 15 is provided with: a nozzle portion 15a that
narrows down the area of the passage and isoentropically
decompresses intermediate-pressure refrigerant that passes through
the variable throttling mechanism 14; and a refrigerant suction
port 15b that is positioned in the same space as the refrigerant
spout of the nozzle portion 15a and sucks in vapor phase
refrigerant from a second evaporator 20 described later.
[0085] In addition, a mixing portion 15c is provided downstream of
the nozzle portion 15a and the refrigerant suction port 15b. The
mixing portion 15c mixes a high-speed refrigerant flow from the
nozzle portion 15a with the refrigerant drawn through the
refrigerant suction port 15b. A diffuser portion 15d that makes a
pressure increasing portion is positioned downstream of the mixing
portion 15c.
[0086] This diffuser portion 15d is formed in such a shape that the
area of the refrigerant passage is gradually increased toward its
outlet. The diffuser portion 15d functions to decelerate a
refrigerant flow to increase the refrigerant pressure. That is, the
diffuser portion 15d has a function of converting the velocity
energy of refrigerant into pressure energy.
[0087] The first evaporator 16 is connected downstream of the
diffuser portion 15d of the ejector 15. The first evaporator 16 is
a heat exchanger that exchanges heat between air sent by a blower
16a for evaporator and refrigerant to evaporate the refrigerant,
and thus produces heat absorbing action.
[0088] The blower 16a for evaporator is driven by an electric motor
16b for driving. The electric motor 16b for driving is so
constructed that it is rotationally driven when applied voltage V2
is outputted from the air conditioning controller 21. Since the
number of revolutions of the electric motor 16b for driving can be
varied by the air conditioning controller 21 varying the applied
voltage V2, the quantity of air sent by the blower 16a for
evaporator can be varied.
[0089] The downstream portion of the first evaporator 16 with
respect to a refrigerant flow is connected to an internal heat
exchanger 17, and the refrigerant outlet of the internal heat
exchanger 17 is connected to the suction side of the compressor
11.
[0090] A branch passage 18 is a refrigerant passage that connects
the sections between the above-mentioned liquid receiver 13 and
variable throttling mechanism 14 and the refrigerant suction port
15b of the ejector 15. Reference character Z denotes the branch
portion of the branch passage 18. The above-mentioned internal heat
exchanger 17 is located in this branch passage 18, and a fixed
throttle 19 is located downstream of the internal heat exchanger
17. In addition, the second evaporator 20 is located downstream of
the fixed throttle 19.
[0091] The internal heat exchanger 17 exchanges heat between the
high-temperature, high-pressure refrigerant that passes through the
branch passage 18 and the low-temperature, low-pressure refrigerant
on the downstream side of the first evaporator 16. As the result of
heat exchange between the refrigerants in the internal heat
exchanger 17, the refrigerant that passes through the branch
passage 18 is cooled. Therefore, the enthalpy difference between
the refrigerants at the refrigerant inlet and outlet of the first
evaporator 16 and the second evaporator 20 can be increased. That
is, their cooling capacity of the first evaporator 16 and the
second evaporator 20 can be increased.
[0092] The fixed throttle 19 adjusts the flow rate of and reduces
the pressure of the refrigerant that flows into the second
evaporator 20. Specifically, the fixed throttle 19 can be
constructed of such a fixed throttle as a capillary tube or an
orifice.
[0093] The throttling opening of the fixed throttle 19 in this
embodiment is set beforehand to a predetermined amount such that
the flow ratio .eta. becomes equal to the optimum flow ratio
.eta.max illustrated in FIG. 28. Here, .eta.=Ge/Gnoz, where Ge is
the flow rate of refrigerant drawn through the refrigerant suction
port 15b of the ejector 15; and Gnoz is the flow rate of
refrigerant that passes through the variable throttling mechanism
14 when the degree of superheat of refrigerant on the outlet side
of the first evaporator 16 becomes equal to a predetermined value
and further passes through the nozzle portion 15a of the ejector
15. The optimum flow ratio .eta.max is a flow ratio at which the
cooling capacity Qer of the entire system approaches the maximum
value.
[0094] This design can be implemented to appropriate values for the
throttling opening of the variable throttling mechanism 14 observed
when the degree of superheat of refrigerant on the outlet side of
the first evaporator 16 becomes equal to a predetermined value. For
example, the area of the refrigerant passage in the nozzle portion
15a of the ejector 15, the dimensions of the mixing portion 15c and
the diffuser portion 15d, and the throttling opening of the fixed
throttle 19 are made at suitable values. Also, this design is made
with the following taken into account: pressure loss in the passage
through which the refrigerant that passes through the variable
throttling mechanism 14 flows; and the passage (branch passage 18)
through which the refrigerant that passes through the fixed
throttle 19 flows.
[0095] The second evaporator 20 is a heat exchanger that evaporates
refrigerant and produces heat absorbing action. In this embodiment,
the first evaporator 16 and the second evaporator 20 are assembled
together so that an integral construction can be formed. More
specifically, the components of the first evaporator 16 and the
second evaporator 20 are formed of aluminum, and they are joined
together by brazing so that they are of integral construction.
[0096] For this reason, the air sent by the above-mentioned blower
16a for evaporator flows as indicated by arrow A. Air is cooled at
the first evaporator 16, and then cooled at the second evaporator
20. That is, one and the same space to be cooled is cooled by using
the first evaporator 16 and the second evaporator 20.
[0097] The air conditioning controller 21 is constructed of a
generally known microcomputer including CPU, ROM, RAM, and the like
and its peripheral circuits. The air conditioning controller 21
carries out varied computation and processing based on control
programs stored in its ROM to control the operation of the various
devices 11a, 11b, 12b, 16b, and so on.
[0098] The air conditioning controller 21 is inputted with
detection signals from a group of various sensors and various
operation signals from an operation panel (not shown).
Specifically, the provided group of sensors includes an ambient
temperature sensor (outside air temperature sensor) that detects
outside air temperature (temperature outside the vehicle
compartment) and the like. The operation panel is provided with a
temperature setting switch for setting the cooling temperature of
the space to be cooled and the like.
[0099] Description will be given to the operation of this
embodiment constructed as mentioned above. When the electromagnetic
clutch 11a is energized by the control output of the air
conditioning controller 21 to bring the electromagnetic clutch 11a
into engagement, rotational driving force is transmitted from the
engine for vehicle, running to the compressor 11. When a control
current In is outputted from the air conditioning controller 21 to
the electromagnetic capacity control valve 11b based on a control
program, the compressor 11 sucks in, compresses, and discharges
vapor phase refrigerant.
[0100] The high-temperature, high-pressure vapor phase refrigerant
compressed in and discharged from the compressor 11 flows into the
radiator 12. At the radiator 12, the high-temperature,
high-pressure refrigerant is cooled by the outside air and
condensed. The high-pressure refrigerant with heat radiated that
flows out of the radiator 12 is separated into vapor phase
refrigerant and liquid phase refrigerant in the liquid receiver 13.
The liquid phase refrigerant that flows out of the liquid receiver
13 is separated at the branch portion Z into a refrigerant flow
toward the variable throttling mechanism 14 and a refrigerant flow
toward the branch passage 18.
[0101] The refrigerant flow heading for the variable throttling
mechanism 14 has its pressure reduced and its flow rate adjusted at
the variable throttling mechanism 14, and then flows into the
ejector 15. At this time, the variable throttling mechanism 14
adjusts the flow rate of the refrigerant passing through the
variable throttling mechanism 14 so that the degree of superheat of
refrigerant on the outlet side of the first evaporator 16
approaches a predetermined value. That is, it adjusts the
refrigerant flow rate Gnoz.
[0102] The refrigerant flow that enters the ejector 15 is further
depressurized through the nozzle portion 15a and expanded.
Therefore, the pressure energy of refrigerant is converted into
velocity energy at the nozzle portion 15a, and the refrigerant is
jetted from the jet port of this nozzle portion 15a at enhanced
speed. The refrigerant (vapor phase refrigerant) that has passed
through the second evaporator 20 in the branch passage 18 is drawn
through the refrigerant suction port 15b by the refrigerant sucking
action produced at this time.
[0103] The refrigerant jetted out of the nozzle portion 15a and the
refrigerant drawn into the refrigerant suction port 15b are mixed
together at the mixing portion 15c located downstream of the nozzle
portion 15a, and flow into the diffuser portion 15d. At this
diffuser portion 15d, the velocity (expansion) energy of
refrigerant is converted into pressure energy by increase in the
area of the passage. Therefore, the pressure of the refrigerant is
raised.
[0104] The refrigerant that flows out of the diffuser portion 15d
of the ejector 15 flows into the first evaporator 16. In the first
evaporator 16, the low-temperature, low-pressure refrigerant
absorbs heat from air sent by the blower 16a for evaporator, and is
evaporated. The vapor phase refrigerant that has passed through the
first evaporator 16 flows into the internal heat exchanger 17, and
exchanges heat between it and the high-temperature, high-pressure
refrigerant that flows through the branch passage 18 at the branch
portion Z. The vapor phase refrigerant that flows out of the
internal heat exchanger 17 is drawn into the compressor 11 and is
compressed again.
[0105] The refrigerant flow that entered the branch passage 18 goes
into the internal heat exchanger 17, and exchanges heat between it
and the low-temperature, low-pressure vapor phase refrigerant that
has flowed out of the first evaporator 16, as mentioned above. The
refrigerant cooled through the internal heat exchanger 17 is
depressurized through the fixed throttle 19 and is changed into
low-pressure refrigerant. This low-pressure refrigerant flows into
the second evaporator 20.
[0106] At the second evaporator 20, the low-pressure inflow
refrigerant absorbs heat from the air sent in and cooled at the
first evaporator 16, and is evaporated. The vapor phase refrigerant
that has passed through the second evaporator 20 is drawn into the
ejector 15 through the refrigerant suction port 15b. As mentioned
above, the throttling opening of the fixed throttle 19 is set
beforehand to a predetermined amount. Therefore, the flow rate Ge
of refrigerant drawn into the refrigerant suction port 15b of the
ejector 15 is such a flow rate that the flow ratio .eta. of it to
Gnoz approaches the optimum flow ratio .eta.max.
[0107] The vapor phase refrigerant evaporated at the second
evaporator 20 is drawn through the refrigerant suction port 15b of
the ejector 15. It is mixed at the mixing portion 15c with the
liquid phase refrigerant that has passed through the nozzle portion
15a, and flows into the first evaporator 16.
[0108] In this embodiment, as mentioned above, the refrigerant on
the downstream side of the diffuser portion 15d of the ejector 15
can be supplied to the first evaporator 16; at the same time, the
refrigerant on the branch passage 18 side can be supplied to the
second evaporator 20 through the fixed throttle 19. Therefore, the
cooling action can be simultaneously produced with the first
evaporator 16 and with the second evaporator 20.
[0109] The refrigerant evaporating pressure of the first evaporator
16 is a pressure obtained after pressurization through the diffuser
portion 15d. Meanwhile, the outlet of the second evaporator 20 is
connected to the refrigerant suction port 15b of the ejector 15.
Therefore, the lowest pressure obtained immediately after
depressurization through the nozzle portion 15a can be applied to
the second evaporator 20. Thus, the refrigerant evaporating
pressure (refrigerant evaporating temperature) of the second
evaporator 20 can be made lower than the refrigerant evaporating
pressure (refrigerant evaporating temperature) of the first
evaporator 16.
[0110] The compression workload of the compressor 11 can be reduced
by an amount by which the inlet pressure of the compressor 11 can
be raised by the pressure raising action at the diffuser portion
15d of the ejector 15. Thus, the power saving effect can be
achieved.
[0111] The variable throttling mechanism 14 in this embodiment
adjusts the refrigerant flow rate Gnoz so that the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 approaches a predetermined value. As a result, the flow ratio
.eta. is so adjusted that it approaches the optimum flow ratio
.eta.max at which the cooling capacity of the entire system is
enhanced. Therefore, the entire cycle can be operated while high
cooling capacity is delivered.
[0112] The degree of superheat of refrigerant on the outlet side of
the first evaporator 16 is controlled; therefore, the liquid phase
refrigerant can be prevented from returning to the compressor 11,
and the stability of the cycle can be ensured.
Second Embodiment
[0113] In the first embodiment, the variable throttling mechanism
14 is located between the branch portion Z and the ejector 15, and
the fixed throttle 19 is located in the branch passage 18. In the
second embodiment, as illustrated in FIG. 2, the variable
throttling mechanism 14 and the fixed throttle 19 are disused, and
a variable throttling mechanism 30 is provided in the branch
passage 18.
[0114] The variable throttling mechanism 30 is a thermal expansion
valve that adjusts the refrigerant flow rate so that the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 approaches a predetermined value. The construction of the
thermal expansion valve can be the same as in the first embodiment.
That is, the valve body of the variable throttling mechanism 30
makes a means for adjusting the flow ratio (.eta.), and the
temperature sensitive cylinder and equalizing pipe of the variable
throttling mechanism 30 make a means for detecting the physical
quantities related to the state of refrigerant in the cycle.
[0115] The area and the like of the refrigerant passage in the
nozzle portion 15a of the ejector 15 in this embodiment are set
such that the flow ratio .eta. of the flow rate Ge of refrigerant
drawn into the refrigerant suction port 15b of the ejector 15 to
the flow rate Gnoz of refrigerant observed when the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 becomes equal to a predetermined value becomes equal to the
optimum flow ratio .eta.max. The other parts of the cycle
configuration of the second embodiment can be made to be the same
as in the first embodiment.
[0116] Therefore, when the cycle in this embodiment is operated,
the variable throttling mechanism 30 adjusts the refrigerant flow
rate Ge so that the degree of superheat of refrigerant on the
outlet side of the first evaporator 16 approaches a predetermined
value. As a result, the flow ratio .eta. is adjusted so that it
approaches the optimum flow ratio .eta.max, and the same effect as
with the first embodiment can be obtained.
Third Embodiment
[0117] In the first embodiment, the variable throttling mechanism
14 is located between the branch portion Z and the ejector 15. In
this third embodiment, as illustrated in FIG. 3, the variable
throttling mechanism 14 shown in FIG. 1 is disused, and a variable
throttling mechanism 31 is provided between the liquid receiver 13
and the branch portion Z.
[0118] The variable throttling mechanism 31 is a thermal expansion
valve that adjusts the refrigerant flow rate so that the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 approaches a predetermined value. The construction of the
thermal expansion valve is the same as in the first embodiment.
That is, the valve body of the variable throttling mechanism 31 is
a means for adjusting the refrigerant flow rate of the entire
cycle; and the temperature sensitive cylinder and equalizing pipe
of the variable throttling mechanism 31 are a means for detecting
the physical quantities related to the state of refrigerant in the
cycle.
[0119] In this third embodiment, the area and the like of the
refrigerant passage in the nozzle portion 15a of the ejector 15 and
the throttling opening of the fixed throttle 19 are set beforehand
to predetermined amounts, so that the flow ratio .eta. becomes
equal to the optimum flow ratio .eta.max with respect to the flow
rate of refrigerant that passes through the variable throttling
mechanism 31 when the degree of superheat of refrigerant on the
outlet side of the first evaporator 16 becomes equal to a
predetermined value. The other aspects of the cycle configuration
of the third embodiment are the same as in the first
embodiment.
[0120] Therefore, when the cycle in this embodiment is operated,
the variable throttling mechanism 31 adjusts the flow rate of
refrigerant that passes through the variable throttling mechanism
31 so that the degree of superheat of refrigerant on the outlet
side of the first evaporator 16 approaches a predetermined value.
As a result, the flow ratio .eta. is adjusted so that it approaches
the optimum flow ratio .eta.max, and the same effect as with the
first embodiment can be obtained.
Fourth Embodiment
[0121] In the first embodiment, the variable throttling mechanism
14 is located between the branch portion Z and the ejector 15. In
this embodiment, as illustrated in FIG. 4, the variable throttling
mechanism 14 of FIG. 1 is disused, and a temperature sensor 51 and
a pressure sensor 52 are provided. The temperature sensor 51
detects the temperature Ts1 of refrigerant on the outlet side of
the first evaporator 16, and the pressure sensor 52 detects its
pressure Ps1.
[0122] The detection values of the temperature sensor 51 and the
pressure sensor 52 are inputted to the air conditioning controller
21. Based on the detection values, the air conditioning controller
21 computes the degree of superheat of refrigerant on the outlet
side of the first evaporator 16. That is, in this embodiment, the
temperature sensor 51 and the pressure sensor 52 are a means for
detecting the physical quantities related to the state of
refrigerant in the cycle.
[0123] The air conditioning controller 21 controls the control
current In so that the computed degree of superheat approaches a
predetermined value, and the electromagnetic capacity control valve
11b controls the discharge capacity of the compressor 11. That is,
in this embodiment, the electromagnetic capacity control valve 11b
is a discharge flow rate varying means.
[0124] In this embodiment, the area and the like of the refrigerant
passage in the nozzle portion 15a of the ejector 15 and the
throttling opening of the fixed throttle 19 are set beforehand to
predetermined amounts so that the flow ratio .eta. becomes equal to
the optimum flow ratio .eta.max with respect to the refrigerant
discharge flow rate of the compressor 11 observed when the degree
of superheat of refrigerant on the outlet side of the first
evaporator 16 becomes equal to a predetermined value. The other
aspects of the cycle configuration of the fourth embodiment are the
same as in the first embodiment.
[0125] Description will be given to the operation of this
embodiment. As an example, it will be assumed that the cooling load
of the first evaporator 16 is increased. When the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 increases and exceeds a predetermined value, the air
conditioning controller 21 increases the compressor discharge
capacity. Consequently, the flow rate of refrigerant that passes
through the first evaporator 16 is increased; therefore, the degree
of superheat of refrigerant on the outlet side of the first
evaporator 16 can be reduced.
[0126] When the cooling load of the first evaporator 16 is lowered,
the degree of superheat of refrigerant on the outlet side of the
first evaporator 16 is lowered. When this degree of superheat
becomes lower than a predetermined value, the air conditioning
controller 21 reduces the compressor discharge capacity.
Consequently, the flow rate of refrigerant that passes through the
first evaporator 16 is lowered. Therefore, the degree of superheat
of refrigerant on the outlet side of the first evaporator 16 can be
increased.
[0127] As mentioned above, the air conditioning controller 21
controls the discharge capacity of the compressor 11 so that the
degree of superheat of refrigerant on the outlet side of the first
evaporator 16 approaches a predetermined value. As a result, the
flow ratio .eta. is also adjusted so that it approaches the optimum
flow ratio .eta.max, and thus the same effect as with the first
embodiment can be obtained.
[0128] In addition, the air conditioning controller 21 varies the
discharge flow rate of the compressor 11 so that the entire cycle
operates with high cooling capacity. Therefore, the discharge flow
rate of the compressor 11 can be prevented from being unnecessarily
increased. As a result, the power saving effect can be further
achieved.
Fifth Embodiment
[0129] The fourth embodiment uses a variable displacement
compressor 11. In this embodiment, as illustrated in FIG. 5, the
variable compressor 11 described above is disused, and a fixed
displacement compressor 61 is provided. The compressor 61 is
provided with an electromagnetic clutch 61a of the same
construction as the electromagnetic clutch 11a. The compressor 61
is rotationally driven by an engine for vehicle running through the
electromagnetic clutch 61a and a belt.
[0130] The air conditioning controller 21 varies applied voltage V2
so that a computed degree of superheat approaches a predetermined
value. That is, in this embodiment, the temperature sensor 51 and
the pressure sensor 52 are a means for detecting the physical
quantities related to the state of refrigerant in the cycle; the
electric motor 16b for driving the blower 16a for evaporator makes
an air quantity adjusting means.
[0131] The structure for determining a flow ratio .eta. with
respect to the area and the like of the refrigerant passage in the
nozzle portion 15a of the ejector 15 and the throttling opening of
the fixed throttle 19 and the other aspects of the cycle
configuration can be made to be the same as in the fourth
embodiment.
[0132] Description will be given to the operation of this fifth
embodiment. As an example, it will be assumed that the cooling load
of the first evaporator 16 is increased. When the degree of
superheat of refrigerant on the outlet side of the first evaporator
16 increases and exceeds a predetermined value, the air
conditioning controller 21 increases the applied voltage V2 applied
to the electric motor 16b for driving.
[0133] When the applied voltage V2 is increased, the quantity of
air sent by the blower 16a for evaporator is increased. For this
reason, the refrigerant evaporating temperature and pressure in the
first evaporator 16 are increased. Thus, the inlet refrigerant
pressure Ps of the compressor 11 can be raised to increase the
density of refrigerant drawn into the compressor 61; therefore, the
refrigerant discharge flow rate of the compressor 61 is virtually
increased. As a result, the degree of superheat of refrigerant on
the outlet side of the first evaporator 16 can be controlled so
that it approaches a predetermined value. When the quantity of air
sent by the blower 16a for evaporator is increased, there is a
possibility that the degree of superheat of refrigerant on the
outlet side of the first evaporator 16 is further increased. To
prevent reduction in the cooling capacity of the entire cycle due
to increase in degree of superheat, this embodiment is applied to a
cycle in which increase in the cooling capacity of the entire cycle
owing to increase in the refrigerant discharge flow rate of the
compressor 61 is greater than the above reduction.
[0134] In this fifth embodiment, as mentioned above, the air
conditioning controller 21 controls the quantity of air sent by the
blower 16a for evaporator so that the degree of superheat of
refrigerant on the outlet side of the first evaporator 16
approaches a predetermined value. Even in this case, completely the
same effect as with the fourth embodiment can be obtained.
Sixth Embodiment
[0135] In the first embodiment, the liquid receiver 13 is located
between the radiator 12 and the branch portion Z, and the variable
throttling mechanism 14 is located between the branch portion Z and
the ejector 15. In the sixth embodiment, as illustrated in FIG. 6,
the liquid receiver 13 and the variable throttling mechanism 14 are
disused; an accumulator 32 for separating liquid phase refrigerant
and vapor phase refrigerant from each other is provided downstream
of the first evaporator 16; and a variable throttling mechanism 33
is provided between the branch portion Z and the ejector 15.
[0136] The variable throttling mechanism 33 is a thermal expansion
valve that adjusts the refrigerant flow rate so that the degree of
superheat of refrigerant on the outlet side of the second
evaporator 20 approaches a predetermined value. The construction of
the thermal expansion valve is the same as in the first embodiment.
In this embodiment, the temperature sensitive cylinder and
equalizing pipe of the variable throttling mechanism 33 displace
the valve body of the variable throttling mechanism 33 according to
the temperature and pressure of refrigerant on the outlet side of
the second evaporator 20.
[0137] That is, the valve body of the variable throttling mechanism
33 makes a means for adjusting the flow ratio (.eta.); the
temperature sensitive cylinder and equalizing pipe of the variable
throttling mechanism 33 make a means for detecting the physical
quantities related to the state of refrigerant in the cycle.
[0138] The throttling opening of the fixed throttle 19 in this
embodiment is set beforehand to a predetermined amount so that the
flow ratio .eta. becomes equal to the optimum flow ratio .eta.max.
The flow ratio .eta. is a ratio of Ge to Gnoz, where Ge is the flow
rate of refrigerant drawn into the refrigerant suction port 15b of
the ejector 15; and Gnoz is the flow rate of refrigerant that
passes through the variable throttling mechanism 33 when the degree
of superheat of refrigerant on the outlet side of the second
evaporator 20 becomes equal to a predetermined value, and further
passes through the nozzle portion 15a of the ejector 15. The other
aspects of the cycle configuration are the same as in the first
embodiment.
[0139] Therefore, when the cycle in this embodiment is operated,
the variable throttling mechanism 33 adjusts the refrigerant flow
rate Gnoz so that the degree of superheat of refrigerant on the
outlet side of the second evaporator 20 approaches a predetermined
value. As a result, the flow ratio .eta. is so adjusted that it
approaches the optimum flow ratio .eta.max; therefore, operation
can be performed with the entire cycle delivering high cooling
capacity.
[0140] Since the accumulator 32 is provided on the outlet side of
the first evaporator 16, liquid phase refrigerant can be prevented
from returning to the compressor 11, and the stability of the cycle
can be ensured.
Seventh Embodiment
[0141] In the sixth embodiment, the variable throttling mechanism
33 is located between the branch portion Z and the ejector 15, and
the fixed throttle 19 is located in the branch passage 18. In this
embodiment, as illustrated in FIG. 7, the variable throttling
mechanism 33 and the fixed throttle 19 are disused, and a variable
throttling mechanism 34 is provided in the branch passage 18.
[0142] The variable throttling mechanism 34 is a thermal expansion
valve that adjusts the refrigerant flow rate so that the degree of
superheat of refrigerant on the outlet side of the second
evaporator 20 approaches a predetermined value. The construction of
the thermal expansion valve is the same as in the sixth embodiment.
That is, the valve body of the variable throttling mechanism 34
makes a means for adjusting the flow ratio (.eta.); and the
temperature sensitive cylinder and equalizing pipe of the variable
throttling mechanism 34 make a means for detecting the physical
quantities related to the state of refrigerant in the cycle.
[0143] The area and the like of the refrigerant passage in the
nozzle portion 15a of the ejector 15 in this embodiment are set
beforehand to predetermined amounts so that the flow ratio .eta.
becomes equal to the optimum flow ratio .eta.max. The flow ratio
.eta. is a ratio of Ge to Gnoz, where Ge is the flow rate of
refrigerant drawn into the refrigerant suction port 15b of the
ejector 15; and Gnoz is the flow rate of refrigerant observed when
the degree of superheat of refrigerant on the outlet side of the
second evaporator 20 becomes equal to a predetermined value. The
other aspects of the cycle configuration are the same as in the
sixth embodiment.
[0144] Therefore, when the cycle in this embodiment is operated,
the variable throttling mechanism 34 adjusts the refrigerant flow
rate Ge so that the degree of superheat of refrigerant on the
outlet side of the second evaporator 20 approaches a predetermined
value. As a result, the flow ratio 11 is so adjusted that it
approaches the optimum flow ratio .eta.max, and thus the same
effect as with the sixth embodiment can be obtained.
Eighth Embodiment
[0145] In the sixth embodiment, the variable throttling mechanism
33 is located between the branch portion Z and the ejector 15. In
this embodiment, as illustrated in FIG. 8, the variable throttling
mechanism 33 is disused, and a variable throttling mechanism 35 is
provided between the radiator 12 and the branch portion Z.
[0146] The variable throttling mechanism 35 is a thermal expansion
valve that adjusts the refrigerant flow rate so that the degree of
superheat of refrigerant on the outlet side of the second
evaporator 20 approaches a predetermined value. The construction of
the thermal expansion valve is the same as in the sixth embodiment.
That is, the valve body of the variable throttling mechanism 35 is
a means for adjusting the refrigerant flow rate of the entire
cycle; and the temperature sensitive cylinder and equalizing pipe
of the variable throttling mechanism 35 are a means for detecting
the physical quantities related to the state of refrigerant in the
cycle.
[0147] In this embodiment, the area and the like of the refrigerant
passage in the nozzle portion 15a of the ejector 15 and the
throttling opening of the fixed throttle 19 are set beforehand to
predetermined amounts so that the following is implemented: the
flow ratio .eta. becomes equal to the optimum flow ratio .eta.max
with respect to the flow rate of refrigerant that passes through
the variable throttling mechanism 35 when the degree of superheat
of refrigerant on the outlet side of the second evaporator 20
becomes equal to a predetermined value. The other aspects of the
cycle configuration are the same as in the sixth embodiment.
[0148] Therefore, when the cycle in this embodiment is operated,
the variable throttling mechanism 35 adjusts the flow rate of
refrigerant passing through the variable throttling mechanism 35 so
that the degree of superheat of refrigerant on the outlet side of
the second evaporator 20 approaches a predetermined value. As a
result, the flow ratio .eta. is so adjusted that it approaches the
optimum flow ratio .eta.max, and thus completely the same effect as
with the sixth embodiment can be obtained.
Ninth Embodiment
[0149] In the sixth embodiment, the variable throttling mechanism
33 is located between the branch portion Z and the ejector 15. In
this ninth embodiment, as illustrated in FIG. 9, the variable
throttling mechanism 33 is disused; and a temperature sensor 53 and
a pressure sensor 54 are provided. The temperature sensor 53
detects the temperature Ts2 of refrigerant on the outlet side of
the second evaporator 20, and the pressure sensor 54 detects its
pressure Ps2.
[0150] The detection values of the temperature sensor 53 and the
pressure sensor 54 are inputted to the air conditioning controller
21. Based on the detection values, the air conditioning controller
21 computes the degree of superheat of refrigerant on the outlet
side of the second evaporator 20. That is, in this embodiment, the
temperature sensor 53 and the pressure sensor 54 make a means for
detecting the physical quantities related to the state of
refrigerant in the cycle.
[0151] The air conditioning controller 21 controls the control
current In so that the computed degree of superheat approaches a
predetermined value, and the electromagnetic capacity control valve
11b adjusts the discharge capacity of the compressor 11. That is,
in this embodiment, the electromagnetic capacity control valve 11b
is a discharge flow rate varying means.
[0152] In this ninth embodiment, the area and the like of the
refrigerant passage in the nozzle portion 15a of the ejector 15 and
the throttling opening of the fixed throttle 19 are set beforehand
to predetermined amounts, so that the flow ratio .eta. becomes
equal to the optimum flow ratio .eta.max with respect to the
refrigerant discharge flow rate of the compressor 11 observed when
the degree of superheat of refrigerant on the outlet side of the
second evaporator 20 becomes equal to a predetermined value. The
other aspects of the cycle configuration are the same as in the
sixth embodiment.
[0153] Therefore, when the cycle in this ninth embodiment is
operated, the air conditioning controller 21 carries out control as
in the fourth embodiment. That is, it controls the refrigerant
discharge flow rate of the compressor 11 so that the degree of
superheat of refrigerant on the outlet side of the second
evaporator 20 approaches a predetermined value. Therefore, the flow
ratio .eta. is also adjusted so that it approaches the optimum flow
ratio .eta.max. As a result, the same effect as with the sixth
embodiment can be obtained.
[0154] Further, as in the fourth embodiment, the discharge flow
rate of the compressor 11 can be prevented from being unnecessarily
increased, and the power saving effect can be further achieved.
10th Embodiment
[0155] The ninth embodiment uses a variable displacement compressor
11. In this embodiment, as illustrated in FIG. 10, the compressor
11 is disused, and a fixed displacement compressor 62 is provided.
The compressor 62 is provided with an electromagnetic clutch 62a of
the same construction as the electromagnetic clutch 11a. The
compressor 62 is rotationally driven by an engine for vehicle
running through the electromagnetic clutch 62a and a belt.
[0156] The air conditioning controller 21 varies applied voltage V2
so that a computed degree of superheat approaches a predetermined
value. That is, in this embodiment, the temperature sensor 53 and
the pressure sensor 54 are a means for detecting the physical
quantities related to the state of refrigerant in the cycle; the
electric motor 16b for driving the blower 16a for evaporator makes
an air quantity adjusting means.
[0157] The design for determining a flow ratio .eta. with respect
to the area and the like of the refrigerant passage in the nozzle
portion 15a of the ejector 15 and the throttling opening of the
fixed throttle 19 and the other aspects of the cycle configuration
are the same as in the ninth embodiment.
[0158] When the cycle in this embodiment is operated, the
refrigerant discharge flow rate of the compressor 62 can be
virtually varied as in the fifth embodiment. The degree of
superheat of refrigerant on the outlet side of the second
evaporator 20 can be controlled so that it approaches a
predetermined value. Therefore, completely the same effect as with
the ninth embodiment can be obtained.
11th Embodiment
[0159] In the sixth embodiment, the variable throttling mechanism
33 is located between the branch portion Z and the ejector 15. In
this 11th embodiment, as illustrated in FIG. 11, the following
measure is taken: the variable throttling mechanism 33 is disused;
an electric variable throttling mechanism 36 is located between the
branch portion Z and the ejector 15; and a temperature sensor 55
and a pressure sensor 56 are provided. The temperature sensor 55
detects the temperature Tc of refrigerant on the outlet side of the
radiator 12 and the pressure sensor 56 detects its pressure Pc.
[0160] The electric variable throttling mechanism 36 includes: a
valve mechanism that adjusts the area of the refrigerant passage;
and a stepping motor that is rotationally driven by a control
signal (pulse signal) outputted from the air conditioning
controller 21. The variable throttling mechanism 36 is a flow
control valve so constructed that, when the stepping motor is
rotated, the valve body of the valve mechanism is displaced and the
area of the refrigerant passage can be continuously adjusted.
[0161] The detection values of the temperature sensor 55 and the
pressure sensor 56 are inputted to the air conditioning controller
21. Based on the detection values, the air conditioning controller
21 computes the degree of subcooling of refrigerant on the outlet
side of the radiator 12. It outputs a control signal (pulse signal)
so that the degree of subcooling of refrigerant on the outlet side
of the radiator 12 approaches a predetermined value. Thus, it
adjusts the area of the refrigerant passage in the electric
variable throttling mechanism 36.
[0162] That is, the electric variable throttling mechanism 36 in
this embodiment is a means for adjusting the flow ratio (.eta.);
and the temperature sensor 55 and the pressure sensor 56 make a
means for detecting the physical quantities related to the state of
refrigerant in the cycle.
[0163] The throttling opening of the fixed throttle 19 in this
embodiment is set beforehand to a predetermined amount so that the
following is implemented: the flow ratio .eta. becomes equal to the
optimum flow ratio .eta.max. The flow ratio .eta. is a ratio of Ge
to Gnoz, where Ge is the flow rate of refrigerant drawn into the
refrigerant suction port 15b of the ejector 15; and Gnoz is the
flow rate of refrigerant that passes through the electric variable
throttling mechanism 36 when the degree of subcooling of
refrigerant on the outlet side of the radiator 12 becomes equal to
a predetermined value and further passes through the nozzle portion
15a of the ejector 15. The other aspects of the cycle configuration
of this embodiment are the same as in the sixth embodiment.
[0164] Therefore, when the cycle in this embodiment is operated,
the air conditioning controller 21 controls the electric variable
throttling mechanism 36. It thereby controls the refrigerant flow
rate Gnoz so that the degree of subcooling of refrigerant on the
outlet side of the radiator 12 approaches a predetermined value. As
a result, the flow ratio .eta. is so adjusted that it approaches
the optimum flow ratio .eta.max, and thus the same effect as with
the sixth embodiment can be obtained.
[0165] In cases where this embodiment is so constructed that the
compressor 11 pressurizes refrigerant to supercritical pressure,
the air conditioning controller 21 cannot compute the degree of
subcooling. In these cases, the air conditioning controller 21
controls the electric variable throttling mechanism 36 so that the
pressure of refrigerant on the outlet side of the radiator 12
becomes equal to a predetermined value.
[0166] The throttling opening of the fixed throttle 19 is set
beforehand to a predetermined amount so that the flow ratio .eta.
becomes equal to the optimum flow ratio .eta.max. The flow ratio
.eta. is a ratio of Ge to Gnoz, where Ge is the flow rate of
refrigerant drawn into the refrigerant suction port 15b of the
ejector 15; and Gnoz is the flow rate of refrigerant that passes
through the electric variable throttling mechanism 36 when the
pressure of refrigerant on the outlet side of the radiator 12
becomes equal to a predetermined value, and further passes through
the nozzle portion 15a of the ejector 15. Thus, even in a cycle in
which refrigerant is brought into supercritical state, completely
the same effect as with the sixth embodiment can be obtained.
[0167] As a modification, this embodiment may be so constructed
that the following is implemented: it is made possible for the air
conditioning controller 21 to store the output (number of pulse
counts) of a control signal (pulse signal) it outputs to the
electric variable throttling mechanism 36; and it stores beforehand
the area of the refrigerant passage in the electric variable
throttling mechanism 36 corresponding to the output (number of
pulse counts) of a control signal (pulse signal) and the throttling
opening of the fixed throttle 19.
[0168] Thus, the air conditioning controller 21 can estimate the
actual flow ratio .eta. by: grasping the area of the refrigerant
passage in the electric variable throttling mechanism 36 based on
the output (number of pulse counts) of a control signal (pulse
signal); and comparing it with the stored throttling opening of the
fixed throttle 19.
[0169] The air conditioning controller 21 displaces the valve body
of the electric variable throttling mechanism 36 so that the actual
flow ratio .eta. approaches the optimum flow ratio lImax. As a
result, operation can be performed with the entire cycle delivering
high cooling capacity.
12th Embodiment
[0170] In the 11th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15, and the fixed throttle 19 is located in the branch
passage 18. In this 12th embodiment, as illustrated in FIG. 12, the
electric variable throttling mechanism 36 and the fixed throttle 19
are disused, and an electric variable throttling mechanism 37 is
provided in the branch passage 18.
[0171] The construction of the electric variable throttling
mechanism 37 is the same as in the 11th embodiment. The air
conditioning controller 21 adjusts the area of the refrigerant
passage in the electric variable throttling mechanism 37 by:
computing the degree of subcooling of refrigerant on the outlet
side of the radiator 12 based on detection values; and outputting a
control signal (pulse signal) so that the degree of subcooling of
refrigerant on the outlet side of the radiator 12 approaches a
predetermined value.
[0172] That is, the electric variable throttling mechanism 37 in
this embodiment makes a means for adjusting the flow ratio (.eta.);
and the temperature sensor 55 and the pressure sensor 56 make a
means for detecting the physical quantities related to the state of
refrigerant in the cycle.
[0173] The area and the like of the refrigerant passage in the
nozzle portion 15a of the ejector 15 in this embodiment are set
beforehand to predetermined amounts so that the flow ratio .eta.
becomes equal to the optimum flow ratio .eta.max. The flow ratio
.eta. is a ratio of Ge to Gnoz, where Ge is the flow rate of
refrigerant drawn into the refrigerant suction port 15b of the
ejector 15; and Gnoz is the flow rate of refrigerant observed when
the degree of subcooling of refrigerant on the outlet side of the
radiator 12 becomes equal to a predetermined value. The other
aspects of the cycle configuration of the 12th embodiment are the
same as in the 11th Embodiment.
[0174] Therefore, when the cycle in this embodiment is operated,
the air conditioning controller 21 controls the electric variable
throttling mechanism 37. It thereby controls the refrigerant flow
rate Ge so that the degree of subcooling of refrigerant on the
outlet side of the radiator 12 approaches a predetermined value. As
a result, the flow ratio .eta. is so adjusted that it approaches
the optimum flow ratio .eta.max, and thus the same effect as with
the 11th embodiment can be obtained.
[0175] This 12th embodiment may be constructed as the 11th
embodiment is. That is, it is made possible for the air
conditioning controller 21 to store the output (number of pulse
counts) of a control signal (pulse signal) it outputs to the
electric variable throttling mechanism 37; and it stores beforehand
the area of the refrigerant passage in the electric variable
throttling mechanism 37 corresponding to the output (number of
pulse counts) of a control signal (pulse signal) and the throttling
opening of the nozzle portion 15a of the ejector 15.
[0176] Thus, the air conditioning controller 21 can estimate the
actual flow ratio .eta., and control the flow ratio q so that it
approaches the optimum flow ratio .eta.max. Therefore, as in the
11th embodiment, operation can be performed with high cooling
capacity delivered.
13th Embodiment
[0177] In the 11th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15. In this embodiment, as illustrated in FIG. 13, the
electric variable throttling mechanism 36 is disused, and an
electric variable throttling mechanism 38 is provided downstream of
the temperature sensor 55 and the pressure sensor 56 between the
radiator 12 and the branch portion Z.
[0178] The construction of the electric variable throttling
mechanism 38 is the same as in the 11th embodiment. The air
conditioning controller 21 adjusts the area of the refrigerant
passage in the electric variable throttling mechanism 38 by:
computing the degree of subcooling of refrigerant on the outlet
side of the radiator 12 based on detection values; and outputting a
control signal (pulse signal) so that the degree of subcooling of
refrigerant on the outlet side of the radiator 12 approaches a
predetermined value.
[0179] That is, the electric variable throttling mechanism 38 in
this embodiment is a means for adjusting the refrigerant flow rate
of the entire cycle; and the temperature sensor 55 and the pressure
sensor 56 are a means for detecting the physical quantities related
to the state of refrigerant in the cycle.
[0180] In this embodiment, the area and the like of the refrigerant
passage in the nozzle portion 15a of the ejector 15 and the
throttling opening of the fixed throttle 19 are set beforehand to
predetermined amounts, so that the flow ratio .eta. becomes equal
to the optimum flow ratio .eta.max with respect to the flow rate of
refrigerant that passes through the electric variable throttling
mechanism 38 when the degree of subcooling of refrigerant on the
outlet side of the radiator 12 becomes equal to a predetermined
value. The other aspects of the cycle configuration of the 13th
embodiment are the same as in the 11th embodiment.
[0181] Therefore, when the cycle in this embodiment is operated,
the electric variable throttling mechanism 38 operates to control
the flow rate of refrigerant passing through the electric variable
throttling mechanism 38 so that the degree of subcooling of
refrigerant on the outlet side of the radiator 12 approaches a
predetermined value. As a result, the flow ratio .eta. is so
adjusted that it approaches the optimum flow ratio .eta.max, and
thus the same effect as with the 11th embodiment can be
obtained.
14th Embodiment
[0182] In the 11th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15. In this embodiment, as illustrated in FIG. 14, the
electric variable throttling mechanism 36 is disused.
[0183] The air conditioning controller 21 controls the control
current In so that the degree of subcooling of refrigerant on the
outlet side of the radiator 12 approaches a predetermined value.
The electromagnetic capacity control valve 11b adjusts the
discharge capacity of the compressor 11. That is, in this
embodiment, the electromagnetic capacity control valve 11b is a
discharge flow rate varying means; and the temperature sensor 55
and the pressure sensor 56 make a means for detecting the physical
quantities related to the state of refrigerant in the cycle.
[0184] In this 14th embodiment, the area and the like of the
refrigerant passage in the nozzle portion 15a of the ejector 15 and
the throttling opening of the fixed throttle 19 are set beforehand
to predetermined amounts so that the following is implemented: the
flow ratio .eta. becomes equal to the optimum flow ratio .eta.max
with respect to the refrigerant discharge flow rate of the
compressor 11 observed when the degree of subcooling of refrigerant
on the outlet side of the radiator 12 becomes equal to a
predetermined value. The other aspects of the cycle configuration
are the same as in the 11th embodiment.
[0185] Therefore, when the cycle in this embodiment is operated,
the following takes place as in the fourth embodiment: the air
conditioning controller 21 controls the control current In so that
the degree of subcooling of refrigerant on the outlet side of the
radiator 12 approaches a predetermined value; and the
electromagnetic capacity control valve 11b that makes a discharge
flow rate varying means adjusts the discharge capacity of the
compressor 11. Therefore, the flow ratio .eta. is also adjusted so
that it approaches the optimum flow ratio .eta.max. As a result,
completely the same effect as with the 11th embodiment can be
obtained.
[0186] Further, as in the fourth embodiment, the discharge flow
rate of the compressor 11 can be prevented from being unnecessarily
increased, and the power saving effect can be further achieved.
15th Embodiment
[0187] The 14th embodiment uses a variable displacement compressor
11. In this embodiment, as illustrated in FIG. 15, the compressor
11 is disused, and a fixed displacement compressor 63 is provided.
The compressor 63 is provided with an electromagnetic clutch 63a of
the same construction as the electromagnetic clutch 11a. The
compressor 63 is rotationally driven by an engine for vehicle
running through the electromagnetic clutch 63a and a belt.
[0188] The air conditioning controller 21 varies the applied
voltage V2 so that a computed degree of subcooling approaches a
predetermined value. That is, in this embodiment, the temperature
sensor 55 and the pressure sensor 56 are a means for detecting the
physical quantities related to the state of refrigerant in the
cycle; and the electric motor 16b for driving the blower 16a for
evaporator makes an air quantity adjusting means.
[0189] The design for determining a flow ratio .eta. with respect
to the area and the like of the refrigerant passage in the nozzle
portion 15a of the ejector 15 and the throttling opening of the
fixed throttle 19 and the other aspects of the cycle configuration
are the same as in the 14th embodiment.
[0190] When the cycle in this embodiment is operated, the following
can be implemented as in the fifth embodiment: the refrigerant
discharge flow rate of the compressor 63 can be virtually varied,
and the degree of subcooling of refrigerant on the outlet side of
the radiator 12 can be controlled so that it approaches a
predetermined value. Therefore, completely the same effect as with
the 14th embodiment can be obtained.
16th Embodiment
[0191] In the 11th embodiment, the temperature sensor 55 and the
pressure sensor 56 are placed on the outlet side of the radiator
12. In this embodiment, as illustrated in FIG. 16, the temperature
sensor 55 and the pressure sensor 56 are disused; a temperature
sensor 57 and a pressure sensor 58 are provided; and a tachometer
11c is provided on the compressor 11. The temperature sensor 57
detects the temperature Tsi of refrigerant on the inlet side of the
compressor 11 between the internal heat exchanger 17 connected to
the outlet of the first evaporator 16 and the compressor 11. The
pressure sensor 58 detects its pressure Psi.
[0192] The tachometer 1c detects the number of revolutions Nc of
the compressor 11, and is a magnetic revolution sensor that detects
change in magnetic flux due to the rotation of the compressor 11
with a Hall element or an MRE element. Or, a number of revolutions
Nc may be computed by detecting a number of engine revolutions Ne
from an engine ECU.
[0193] The detection values of the temperature sensor 57, pressure
sensor 58, and tachometer 11c are inputted to the air conditioning
controller 21. The air conditioning controller 21 computes the
inlet refrigerant density of the compressor 11 based on Tsi and
Psi. Then, it computes the refrigerant discharge flow rate of the
compressor 11 from this inlet refrigerant density, the number of
revolutions Nc, and the control current In.
[0194] In the air conditioning controller 21, there are beforehand
stored the area of the refrigerant passage corresponding to the
output (number of pulse counts) of a control signal (pulse signal)
outputted to the electric variable throttling mechanism 36 and the
throttling opening of the fixed throttle 19. The area of the
refrigerant passage in the electric variable throttling mechanism
36 is varied so that the flow ratio .eta. becomes equal to the
optimum flow ratio .eta.max with respect the computed refrigerant
discharge flow rate. The other aspects of the cycle configuration
of the 16th embodiment are the same as in the 11th embodiment.
[0195] That is, in this 16th embodiment, the electric variable
throttling mechanism 36 is a means for adjusting the flow ratio
(.eta.); and the temperature sensor 57, pressure sensor 58, and
tachometer 11c are a means for detecting the physical quantities
related to the state of refrigerant in the cycle.
[0196] Therefore, when the cycle in this embodiment is operated,
the air conditioning controller 21 computes the refrigerant
discharge flow rate of the compressor 11. It adjusts the area of
the refrigerant passage in the electric variable throttling
mechanism 36 so that the flow ratio .eta. becomes equal to the
optimum flow ratio .eta.max based on the following: the computed
refrigerant discharge flow rate; and the area of the refrigerant
passage corresponding to the output (number of pulse counts) of a
control signal (pulse signal) to the electric variable throttling
mechanism 36 and the throttling opening of the fixed throttle 19,
stored beforehand. As a result, the same effect as in the 11th
embodiment can be obtained.
17th Embodiment
[0197] In the 16th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15, and the fixed throttle 19 is located in the branch
passage 18. In this embodiment, as illustrated in FIG. 17, the
electric variable throttling mechanism 36 and the fixed throttle 19
are disused, and an electric variable throttling mechanism 39 is
provided in the branch passage 18.
[0198] As in the 16th embodiment, the air conditioning controller
21 computes the refrigerant discharge flow rate of the compressor
11 from Tsi, Psi, the number of revolutions Nc, and the control
current In. In the air conditioning controller 21, there are
beforehand stored the area of the refrigerant passage corresponding
to the output (number of pulse counts) of a control signal (pulse
signal) outputted to the electric variable throttling mechanism 39
and the throttling opening of the nozzle portion 15a of the ejector
15.
[0199] The air conditioning controller 21 controls the area of the
refrigerant passage in the electric variable throttling mechanism
39 so that the flow ratio .eta. becomes equal to the optimum flow
ratio .eta.max with respect to the computed refrigerant discharge
flow rate. The other aspects of the cycle configuration are the
same as in the 16th embodiment.
[0200] That is, in this embodiment, the electric variable
throttling mechanism 39 is a means for adjusting the flow ratio
(.eta.); and the temperature sensor 57, pressure sensor 58, and
tachometer 11c are a means for detecting the physical quantities
related to the state of refrigerant in the cycle.
[0201] Therefore, when the cycle in this embodiment is operated,
the air conditioning controller 21 computes the refrigerant
discharge flow rate of the compressor 11. Then, it adjusts the area
of the refrigerant passage in the variable throttling mechanism 39
so that the flow ratio .eta. becomes equal to the optimum flow
ratio .eta.max based on the following: the computed refrigerant
discharge flow rate; and the area of the refrigerant passage
corresponding to the output (number of pulse counts) of a control
signal (pulse signal) to the electric variable throttling mechanism
39 and the throttling opening of the nozzle portion 15a of the
ejector 15, stored beforehand. As a result, in the 17th embodiment,
the same effect as with the 16th embodiment can be obtained.
18th Embodiment
[0202] In the 16th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15. In this embodiment, as illustrated in FIG. 18, the
electric variable throttling mechanism 36 is disused, and an
electric variable throttling mechanism 40 is provided between the
radiator 12 and the branch portion Z.
[0203] As in the 16th embodiment, the air conditioning controller
21 computes the refrigerant discharge flow rate of the compressor
11 from Tsi, Psi, the number of revolutions Nc, and the control
current In. In the air conditioning controller 21, there is
beforehand stored the area of the refrigerant passage corresponding
to the output (number of pulse counts) of a control signal (pulse
signal) outputted to the electric variable throttling mechanism
40.
[0204] In this embodiment, the area and the like of the refrigerant
passage in the nozzle portion 15a of the ejector 15 and the
throttling opening of the fixed throttle 19 are set beforehand to
predetermined amounts so that the following is implemented: the
flow ratio .eta. becomes equal to the optimum flow ratio .eta.max
when the flow rate of refrigerant passing through the electric
variable throttling mechanism 40 becomes equal to a predetermined
value. The other aspects of the cycle configuration are the same as
in the 16th embodiment.
[0205] That is, in this embodiment, the electric variable
throttling mechanism 40 is a means for adjusting the refrigerant
flow rate of the entire cycle; and the temperature sensor 57,
pressure sensor 58, tachometer 11c are a means for detecting the
physical quantities related to the state of refrigerant in the
cycle.
[0206] Therefore, when the cycle in this embodiment is operated,
the air conditioning controller 21 computes the refrigerant
discharge flow rate of the compressor 11. Therefore, the area of
the refrigerant passage in the electric variable throttling
mechanism 40 is adjusted so that the flow rate of refrigerant
passing through the electric variable throttling mechanism 40
becomes equal to a predetermined value, based on the following: the
computed refrigerant discharge flow rate; and the area of the
refrigerant passage corresponding to the output (number of pulse
counts) of a control signal (pulse signal) to the electric variable
throttling mechanism 40, stored beforehand. As a result, in the
18th embodiment, the flow ratio .eta. approaches the optimum flow
ratio .eta.max, and thus the same effect as with the 16th
embodiment can be obtained.
19th Embodiment
[0207] In the 16th embodiment, the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15, and a variable displacement compressor 11 is used. In
this embodiment, as illustrated in FIG. 19, the electric variable
throttling mechanism 36 and the compressor 11 are disused, and a
fixed displacement compressor 64 is provided.
[0208] The compressor 64 is provided with an electromagnetic clutch
64a of the same construction as the electromagnetic clutch 11a. The
compressor 64 is rotationally driven by an engine for vehicle
running through the electromagnetic clutch 64a and a belt. In
addition, the compressor 64 is provided with a tachometer 64c that
is of the same construction as the tachometer 11c and detects the
number of revolutions Nc of the compressor 64.
[0209] As in the 16th embodiment, the air conditioning controller
21 computes the refrigerant discharge flow rate of the compressor
11 from Tsi, Psi, the number of revolutions Nc, and the control
current In. It adjusts the applied voltage V2 so that the computed
refrigerant discharge flow rate approaches a predetermined value,
and thereby adjusts the air quantity of the blower 16a for
evaporator.
[0210] In this embodiment, the area of the refrigerant passage in
the nozzle portion 15a of the ejector 15 and the throttling opening
of the fixed throttle 19 are set beforehand to predetermined
amounts so that the following is implemented: the flow ratio .eta.
becomes equal to the optimum flow ratio .eta. max when the
refrigerant discharge flow rate of the compressor 64 becomes equal
to a predetermined value. The other aspects of the cycle
configuration are the same as in the 16th embodiment.
[0211] That is, in this embodiment, the electric motor 16b for
driving the blower 16a for evaporator is an air quantity adjusting
means; and the temperature sensor 57, pressure sensor 58, and
tachometer 64c are a means for detecting the physical quantities
related to the state of refrigerant in the cycle.
[0212] When the cycle in this embodiment is operated, the following
can be implemented as in the fifth embodiment: the refrigerant
discharge flow rate of the compressor 64 can be virtually varied,
and the refrigerant discharge flow rate can be so adjusted that it
approaches a predetermined value. Therefore, in the 19.sup.th
embodiment, completely the same effect as with the 16th embodiment
can be obtained.
20th Embodiment
[0213] In the above-described 11th embodiment, the air conditioning
controller 21 controls the electric variable throttling mechanism
36 to make the flow ratio .eta. approach the optimum flow ratio
.eta.max. Thus, operation is performed with the entire cycle
delivering high cooling capacity. In this embodiment, as
illustrated in FIG. 20, when a request to rapidly cool the space to
be cooled is received from a user, the air conditioning controller
21 closes the electric variable throttling mechanism 36, and
thereby rapidly cools the space to be cooled. (This is hereafter
referred to as rapid cooling operation.)
[0214] The rapid cooling switch 65 provided in the operation panel
is an operating member operated by the user, and the actuating
signal of the rapid cooling switch 65 is inputted to the air
conditioning controller 21. The rapid cooling switch 65 corresponds
to the inputting means in the invention.
[0215] When the rapid cooling switch 65 is turned on and an
actuating signal from the rapid cooling switch 65 is inputted to
the air conditioning controller 21, the air conditioning controller
21 determines that it is required to rapidly cool the space to be
cooled. Therefore, the air conditioning controller 21 corresponds
to the determining means in the invention.
[0216] When the air conditioning controller 21 determines that it
is required to rapidly cool the space to be cooled, the air
conditioning controller 21 carries out control so as to close the
refrigerant passage in the electric variable throttling mechanism
36. Thus, the refrigerant flow to the nozzle portion 15a of the
ejector 15 is interrupted.
[0217] When the refrigerant flow to the nozzle portion 15a of the
ejector 15 is interrupted, the divided refrigerant all flows along
the branch passage 18; therefore, the refrigerant flow rate of the
branch passage 18 is increased. When the refrigerant flow rate of
the branch passage 18 is increased, the flow rate of the
refrigerant flowing into the fixed throttle 19 is increased, and
the flow velocity of refrigerant is increased. Since the amount of
depressurization in the fixed throttle 19 is increased for this
reason, the pressure of refrigerant lowered through the fixed
throttle 19 becomes lower as compared with when the refrigerant
flow is separated.
[0218] Thus, the refrigerant evaporating pressure of the second
evaporator 20 can be lowered, and its refrigerant evaporating
temperature can be lowered. As a result, the air temperature from
the second evaporator 20 is lowered, and thus rapid cooling can be
carried out.
[0219] In this embodiment, the rapid cooling operation is added to
the ejector cycle system in the 11th embodiment. Similarly with
this embodiment, the rapid cooling operation can also be added to
other embodiments in which the electric variable throttling
mechanism 36 is located between the branch portion Z and the
ejector 15. Specifically, similarly with this embodiment, the rapid
cooling operation can be added to the 16th embodiment.
21st Embodiment
[0220] In the 20th embodiment, the rapid cooling operation is
performed by closing the electric variable throttling mechanism 36.
In this embodiment, the rapid cooling operation is performed by
increasing the discharge capacity of the compressor 11.
[0221] The cycle configuration in this embodiment is the same as in
the 20th embodiment shown in FIG. 20.
[0222] When the rapid cooling switch 65 is turned on and an
actuating signal from the rapid cooling switch 65 is inputted to
the air conditioning controller 21, the following takes place: the
air conditioning controller 21 controls the control current In it
outputs to the electromagnetic capacity control valve 1b, and
thereby increases the discharge capacity of the compressor 11.
[0223] When the discharge capacity of the compressor 11 is
increased, the following are both increased: the flow rate Gnoz of
refrigerant that passes through the nozzle portion 15a of the
ejector 15; and the flow rate Ge of refrigerant drawn into the
refrigerant suction port 15b of the ejector 15. For this reason,
the cooling capability of refrigerant becomes excessive relative to
the cooling capability of air in the first evaporator 16 and the
second evaporator 20. Consequently, the cycle is balanced so that
the low pressure is lowered and the refrigerant flow rate is
reduced.
[0224] Thus, the refrigerant evaporating pressures of the first
evaporator 16 and the second evaporator 20 can be lowered, and
their refrigerant evaporating temperatures can be lowered. As a
result, the air temperatures from the first evaporator 16 and the
second evaporator 20 are lowered, and thus rapid cooling can be
carried out.
[0225] Further, the air conditioning controller 21 controls the
electric variable throttling mechanism 36. It thereby controls the
refrigerant flow rate Gnoz so that the degree of subcooling of
refrigerant on the outlet side of the radiator 12 approaches a
predetermined value. As a result, the flow ratio .eta. is so
adjusted that it approaches the optimum flow ratio .eta.max, and
thus the rapid cooling operation can be performed with the entire
cycle delivering high cooling capacity.
[0226] This embodiment may be so constructed as described below.
When the discharge capacity of the compressor 11 is increased, the
electric variable throttling mechanism 36 is controlled so that the
flow rate Gnoz of refrigerant passing through the nozzle portion
15a of the ejector 15 is not increased. In this case, only the flow
rate Ge of refrigerant drawn into the refrigerant suction port 15b
of the ejector 15 is increased. Thus, rapid cooling may be carried
out by lowering only the air temperature from the second evaporator
20.
[0227] In this embodiment, the rapid cooling operation is added to
the ejector cycle system in the 11th embodiment. Similarly with
this embodiment, the rapid cooling operation can also be added to
other embodiments in which the variable displacement compressor 11
is used. Specifically, similarly with this embodiment, the rapid
cooling operation can be added to the first to fourth, sixth to
ninth, 12th to 14th, and 16th to 18th embodiments.
22nd Embodiment
[0228] In the 20th embodiment, the rapid cooling operation is
performed by closing the electric variable throttling mechanism 36.
In this embodiment, the rapid cooling operation is performed by
reducing the quantity of air sent by the blower 16a for
evaporator.
[0229] The cycle configuration in this embodiment is the same as in
the 20th embodiment shown in FIG. 20.
[0230] When the rapid cooling switch 65 is turned on and an
actuating signal from the rapid cooling switch 65 is inputted to
the air conditioning controller 21, the following takes place: the
air conditioning controller 21 lowers the applied voltage V2
applied to the electric motor 16b for driving. When the applied
voltage V2 is lowered, the quantity of air sent by the blower 16a
for evaporator is reduced.
[0231] When the quantity of air sent by the blower 16a for
evaporator is reduced, the cooling capability of refrigerant
becomes excessive relative to the cooling capability of air in the
first evaporator 16 and the second evaporator 20. Consequently, the
cycle is balanced so that the low pressure is lowered and the
refrigerant flow rate is reduced.
[0232] Thus, the refrigerant evaporating pressures of the first
evaporator 16 and the second evaporator 20 can be lowered, and
their refrigerant evaporating temperatures can be lowered. As a
result, the air temperatures from the first evaporator 16 and the
second evaporator 20 are lowered, and thus rapid cooling can be
carried out.
[0233] Further, the air conditioning controller 21 controls the
electric variable throttling mechanism 36. It thereby controls the
refrigerant flow rate Gnoz so that the degree of subcooling of
refrigerant on the outlet side of the radiator 12 approaches a
predetermined value. As a result, the flow ratio .eta. is so
adjusted that it approaches the optimum flow ratio .eta.max, and
thus the rapid cooling operation can be performed with the entire
cycle delivering high cooling capacity.
[0234] In this embodiment, the rapid cooling operation is added to
the ejector cycle system in the 11th embodiment. Similarly with
this embodiment, the rapid cooling operation can also be added to
other embodiments in which the quantity of air sent by the blower
16a for evaporator is adjusted with the electric motor 16b for
driving. Specifically, similarly with this embodiment, the rapid
cooling operation can be added to the first to 10th and 12th to
19th embodiments.
23rd Embodiment
[0235] In the 20th embodiment, the rapid cooling operation is
performed by closing the electric variable throttling mechanism 36.
In this embodiment, as illustrated in FIG. 21, the rapid cooling
operation is performed by increasing the degree of superheat of
refrigerant on the outlet side of the first evaporator 16.
[0236] FIG. 21 illustrates a system in which an electric variable
throttling mechanism 41 and the rapid cooling switch 65 are added
to the cycle in the fourth embodiment. The construction of the
electric variable throttling mechanism 41 is the same as in the
11th embodiment, and it is located between the branch portion Z and
the ejector 15. Similarly with the 20th to 22nd embodiments, the
rapid cooling switch 65 is an operating member that is provided in
the operation panel and is operated by a user.
[0237] In this embodiment, the detection values of the temperature
sensor 51 and the pressure sensor 52 are inputted to the air
conditioning controller 21; and based on the detection values, the
air conditioning controller 21 computes a degree of superheat of
refrigerant on the outlet side of the first evaporator 16. Further,
the air conditioning controller 21 controls the control current In
so that the computed degree of superheat approaches a predetermined
value. The electromagnetic capacity control valve 11b adjusts the
discharge capacity of the compressor 11.
[0238] When the rapid cooling switch 65 is turned on and an
actuating signal from the rapid cooling switch 65 is inputted to
the air conditioning controller 21, the following takes place: the
air conditioning controller 21 increases a predetermined value of
degree of superheat by a predetermined amount. Further, the air
conditioning controller 21 controls the electric variable
throttling mechanism 41. It thereby controls the refrigerant flow
rate Gnoz so that the computed degree of superheat approaches to a
predetermined value obtained by increasing it by the predetermined
amount.
[0239] When the degree of superheat of refrigerant on the outlet
side of the first evaporator 16 is increased by a predetermined
amount, as mentioned above, the following takes place: the cooling
capability of refrigerant becomes excessive relative to the cooling
capability of air in the first evaporator 16. Consequently, the
cycle is balanced so that the low pressure is lowered and the
refrigerant flow rate is reduced.
[0240] As a result, the refrigerant evaporating pressure of the
first evaporator 16 can be lowered, and the air temperature from
the first evaporator 16 is lowered. Therefore, rapid cooling can be
carried out.
[0241] In this embodiment, the air temperature flowing out of the
first evaporator 16 is lowered by increasing the degree of
superheat of refrigerant on the outlet side of the first evaporator
16. The air temperature from the second evaporator 20 may be
lowered by increasing the degree of superheat of refrigerant on the
outlet side of the second evaporator 20.
24th Embodiment
[0242] The ejector cycle system in this 24th embodiment is applied
to an air conditioner for vehicle. Fluorocarbon refrigerant,
hydrocarbon refrigerant, carbon dioxide, or the like can be used
for the refrigerant.
[0243] The ejector cycle 150 in the 24th embodiment illustrated in
FIG. 22 includes: a compressor 11 that compresses refrigerant; a
condenser 12 that cools and condenses high-temperature,
high-pressure gas refrigerant; a variable expansion valve 43 and a
fixed expansion valve 44 (flow control devices) that depressurize
the high-temperature, high-pressure refrigerant at the outlet of
the condenser 12; an ejector 15 that delivers suction force by the
refrigerant, depressurized at the variable expansion valve 43,
passing through it and being jetted from its nozzle at high speed;
a first evaporator 16 that evaporates the refrigerant in two
phases, vapor and liquid, discharged from the ejector 15 and
thereby causes the evaporated refrigerant to exchange heat between
it and air-conditioning air (external fluid); and a second
evaporator 20 whose refrigerant outlet is connected to the suction
port 15b of the ejector 15 and which evaporates the refrigerant in
two phases, vapor and liquid, depressurized at the fixed expansion
valve 44 and causes the evaporated refrigerant to exchange heat
between it and air-conditioning air (external fluid). As
illustrated in FIG. 22, these components are connected with one
another through pipes. The variable expansion valve 43 and the
fixed expansion valve 44 form flow control devices.
[0244] The pipe on the refrigerant outlet side of the condenser 12
is branched into two lines at an upstream side of the ejector 15.
One refrigerant pipe line 42 is connected to a refrigerant inlet
(nozzle inlet) 15g of the ejector 15 through the variable expansion
valve 43. The other refrigerant pipe line 40 (bypass path) is
connected to the refrigerant inlet (nozzle inlet) of the second
evaporator 20 through the fixed expansion valve 44. A refrigerant
outlet 15h of the ejector 15 is connected to the refrigerant inlet
of the first evaporator 16, and refrigerant that flows out of the
first evaporator 16 returns to the compressor 11. The refrigerant
outlet of the second evaporator 20 is connected to the suction port
15b of the ejector 15, and refrigerant in two phases, vapor and
liquid, is caused to flow in the second evaporator 20 by suction
force produced by the refrigerant being jetted from the nozzle of
the ejector 15 at high speed. The ejector 15 in this embodiment is
of opening variable type, but it may have no opening adjusting
function.
[0245] Hereafter, description will be given to the operation of
this embodiment with respect to cases where the ejector cycle
system applied to an air conditioner for vehicle is used for air
conditioning.
[0246] The high-temperature, high-pressure refrigerant compressed
by the compressor 11 is cooled by the outside air and is condensed
in the condenser 12. As illustrated in FIG. 22, the refrigerant
flow is thereafter divided. The refrigerant flow in one line passes
through the variable expansion valve 43, and is depressurized and
expanded into refrigerant in two phases, vapor and liquid. This
refrigerant from the variable expansion valve 43 flows into the
ejector 15, and is jetted from the nozzle of the ejector 15 at high
speed and thereby delivers suction force. Further, the refrigerant
flowing out of the ejector 15 flows into the first evaporator 16.
The refrigerant flowing into the first evaporator 16 is evaporated
by exchanging heat with air-conditioning air (external fluid) to
cool the air-conditioning air (external fluid). The refrigerant in
the other line is depressurized and expanded into refrigerant in
two phases, vapor and liquid at the fixed expansion value 44, and
flows into the second evaporator 20. The refrigerant flowing into
the second evaporator 20 is evaporated there and thereby exchanges
heat between it and the air-conditioning air (external fluid) to
cool the air-conditioning air.
[0247] In the ejector cycle system 150 in this embodiment, the
state of superheated gas (SH) on the refrigerant outlet side of the
first evaporator 16 is measured with a measuring means 49 (a
measuring unit) provided there. Then, the opening of the variable
expansion valve 43 is adjusted according to the thermal
(refrigeration) load. It is preferable that the state of
superheated gas (SH) should be expressed by the temperature
difference between saturated vapor temperature and superheated gas
(vapor) temperature.
[0248] Description will be given to the operation control in this
embodiment with reference to the flowchart in FIG. 23. The control
of the ejector cycle system 150, including the control shown in
this flowchart, is carried out by a controller not shown in FIG.
24. This controller provides a controlling means.
[0249] When control is started at Step S1, the operation proceeds
to Step S2, and a controllable factor A is sensed. The controllable
factor A in this embodiment is the state of superheated gas (SH) at
the refrigerant outlet of the second evaporator 20, and is sensed
by a first sensing means 45 in FIG. 22. In general, the state of
superheated gas (SH) is the temperature difference between the
saturated vapor temperature of refrigerant and superheated gas
(vapor) temperature. The controllable factor A is detected during
normal operation in which refrigerant is let through the second
evaporator 20 by the sucking action of the ejector 15. The
controllable factor A may be continuously sensed during the normal
operation. The controllable factor A may be continuously sensed
while the controller is in operation. After the controllable factor
A is sensed at Step S2, the operation proceeds to Step S3. At Step
S3, determination is made with respect to determination condition
B. The determination condition B in this embodiment is whether SH
is within a specified range or not (i.e., whether the
above-mentioned temperature difference is equal to or smaller than
a predetermined value in general cases). When SH is within the
specified range of the determination condition B, the cycle is
normally operating and the oil retained in the evaporator does not
exceed its limit. Therefore, the operation proceeds to Step S5, and
it is continued. That is, the operation returns to Step S1, and the
control is continued.
[0250] When negative determination is made at Step S3, that is,
when SH is out of the specified range of the determination
condition B, the following operation is performed: it is determined
that the operating state is not normal (the oil retained in the
evaporator is beyond its limit), and the operation proceeds to Step
S4. At Step S4, a means C is taken. The means C in this embodiment
is an operation in which the line 42 of the variable expansion
valve 43 (the path indicated by a broken line arrow in FIG. 22) is
virtually blocked by adjusting the opening of the variable
expansion valve 43 or the ejector 15 to narrow or close it. Thus,
the flow rate of refrigerant flowing along the bypass path 40
including the fixed expansion valve 44 is increased. The
refrigerant from the fixed expansion valve 44 passes through the
second evaporator 20, and flows through the suction port 15b of the
ejector 15 to the first evaporator 16 and returns to the compressor
11 (the path indicated by a solid line arrow). Since the control
process returns from Step S4 to Step S2, the controllable factor A
is continuously detected. Therefore, the variable expansion valve
43 or the ejector 15 is kept in opening adjusting state until the
controllable factor A, that is, SH falls within the specified
range. Thus, the oil retained at some point in the cycle is
effectively returned to the compressor 11. The flow-down means for
causing the oil retained in the second evaporator 20 to flow down
in this embodiment is provided by: the controlling means provided
by the controller; and the flow control device that increases the
quantity of refrigerant flowing into the second evaporator 20. To
increase the quantity of refrigerant forcibly and directly flowing
from upstream into the second evaporator 20, the flow control
device is provided between the high pressure side of the cycle and
the upstream side of the second evaporator 20. The flow control
device can be provided by a valve mechanism that increases the flow
rate of refrigerant flowing into the second evaporator 20 and
reduces the flow rate of refrigerant flowing into the nozzle of the
ejector 15. The valve mechanism can be provided by the valve 43
placed in the refrigerant path to the ejector 15.
[0251] In cases where the cycle is operated for a long time with a
small quantity of refrigerant circulating in the cycle at time of
low load when the load on the evaporators is small (when the flow
rate is very low) or other like cases, oil is not taken out of the
evaporators by the refrigerant and is retained especially in the
second evaporator 20. The oil staying in the evaporators causes
degradation in the capability of each single evaporator. The
concentration of oil is an index different from the state of
superheated refrigerant gas (SH) and the state of superheated
refrigerant liquid (SC). Therefore, this phenomenon cannot be
prevented by techniques in the past. To cope with this, the
following measure is taken: the state of superheated refrigerant
gas (SH) at the refrigerant outlet of the second evaporator is
adopted as the controllable factor; when a state in which oil is
accumulated, as mentioned above, is sensed, adjustment is made so
that the opening of the variable expansion valve or the ejector is
reduced; the state of superheated refrigerant gas (SH) at the
outlet of the second evaporator is thereby kept within a
predetermined range. Thus, the retention of oil in the second
evaporator 20 can be prevented, and the intended capability of the
evaporator 20 can be delivered.
[0252] When oil is retained in the second evaporator 20 or the
low-pressure side, the quantity (concentration) of oil circulating
in the cycle is reduced. This can cause such trouble as seizure of
the compressor. Generally, when the cycle is operated at low load
for a long time, it is required to ensure a certain quantity of
circulating oil. When the oil in the evaporators is returned to the
compressor side, the oil lubricity of the compressor can be
ensured, and breakage of the compressor, including seizure, can be
prevented.
25th Embodiment
[0253] Description will be given to the 25th embodiment of the
invention with reference to FIG. 23 and FIG. 24. The construction
of the ejector cycle system in this embodiment is substantially the
same as the construction of the 24th embodiment. A difference from
the 24th embodiment is as follows: the refrigerant inlet of the
second evaporator 20 is additionally included in the sensing point
for controllable factor A, and a second sensing means 46 is added
in connection therewith.
[0254] In this embodiment, the controllable factor A sensed at Step
S2 in FIG. 23 is either the refrigerant temperature difference or
pressure loss (pressure drop) between the refrigerant inlet and
outlet of the second evaporator 20. When the quantity of
circulating refrigerant is small, the heat load (external load) of
air-conditioning air (external fluid) that heats refrigerant in the
second evaporator 20 is relatively increased. Therefore, the
temperature of superheated vapor (gas) of refrigerant is raised.
When the refrigerant flow rate is reduced, the pressure drop
between the outlet and inlet of the second evaporator 20 is
reduced. With respect to the determination condition B, the
following operation is performed at Step S3: when the refrigerant
temperature difference is out of a specified range, that is, the
temperature of superheated vapor (gas) of refrigerant is higher
than a predetermined value, it is determined that the operation is
not normal. Or, when the pressure drop is out of a specified range,
it is determined that the operation is not normal. Then, the
operation proceeds to Step S4, and the means C is taken. The means
C in this embodiment may be different from that in the 24th
embodiment. As the means C, the following operation is performed:
the compressor 11 is temporarily turned off, that is, stopped, and
the liquid refrigerant is settled. As the result of this operation,
the refrigerant in the first and second evaporators 16 and 20 flows
to the inlet of the compressor 11 without increase in the liquid
refrigerant containing oil. Therefore, the oil in proximity to the
first evaporator 16 and that in proximity to the second evaporator
20 are simultaneously recovered. The flow-down means for causing
the oil retained in the second evaporator 20 to flow down in this
embodiment is provided by: the controlling means provided by the
controller; and a stopping mechanism that temporarily stops the
compressor 11. The stopping mechanism can be provided by: a clutch
means provided in a power transmission path for stopping power
supply to the compressor 11; a means for stopping a motor as a
power source; or a means for stopping a power plant as a power
source.
[0255] For example, in this embodiment, refrigerant temperature
difference and/or pressure loss (pressure drop) between the
refrigerant inlet and outlet of the second evaporator 20 can be
adopted as the controllable factor A. In this case, an abnormal
state in which oil is accumulated is sensed, the compressor is
temporarily turned off and the liquid refrigerant is settled. Thus,
the quantity of gas refrigerant circulating in the cycle is
increased. As the result of this operation, it is possible to
recover oil and prevent oil from being retained in the second
evaporator 20, and to deliver the intended capability of the
evaporator 20.
[0256] Therefore, the oil lubricity of the compressor 11 can be
ensured, and breakage of the compressor 11, including seizure, can
be prevented.
26th Embodiment
[0257] Description will be given to the 26th embodiment of the
invention with reference to FIG. 23 and FIG. 25. The construction
of the ejector cycle system in this embodiment is substantially the
same as the construction of the 24th embodiment. A difference from
the 24th embodiment is as follows: the suction port 15b and the
refrigerant outlet 15h of the ejector 15 are used as sensing points
for controllable factor A; and a third sensing means 47 and a
fourth sensing means 48 are provided in connection therewith. The
first sensing means 45 is not provided. Therefore, the controllable
factor A is the amount of pressure rising (buildup pressure
difference) between the suction port 15b (inlet) and refrigerant
outlet 15h of the ejector 15.
[0258] In this embodiment, the controllable factor A sensed at Step
S2 is the amount of pressure rising between the suction port 15b
and refrigerant outlet 15h of the ejector 15. With respect to the
determination condition B, the following operation is performed at
Step S3: when this amount of pressure rising (buildup pressure
difference) is out of a specified range, that is, smaller than a
predetermined value, it is determined that the suction force of the
ejector 15 is small and the operation is not normal. The operation
proceeds to Step S4, and the means C is taken. The means C in this
embodiment is also different from that in the 24th embodiment. As
the means C, operation is performed so as to suppress cooling by
the outside air (increase the outside air load) in the condenser
12. Possible concrete methods for this operation include: the
operation of reducing the opening of a damper for the outside air
or the number of revolutions of a fan for outside air supply to
reduce the outside air quantity (or wind velocity); and the
operation of raising the outside air temperature. Thus, the amount
of refrigerant condensed at the condenser 12 is reduced. Therefore,
the flow rate of gas refrigerant flowing along the ejector cycle
system 150 is increased, and the oil in the evaporators and the
like is recovered. The amount of pressure rising at the ejector 15
is increased, and as a result, SH is varied so that it changed
within the specified range of the determination condition B. The
flow-down means for causing the oil retained in the second
evaporator 20 to flow down in this embodiment is provided by: the
controlling means provided by the controller; and a condensing
control device that prevents refrigerant from being condensed in
the condenser 12 to increase the quantity of circulating
refrigerant, and accordingly increases the quantity of refrigerant
flowing into the second evaporator 20. The condensing control
device can be provided by a means for hindering refrigerant cooling
at the condenser 12 or a means for increasing the load of the
outside air that is a medium for heat exchange with the condenser
12.
[0259] The following measure is taken: pressure rising between the
suction port 15b and refrigerant outlet 15h of the ejector 15 is
adopted as the controllable factor; when an abnormal state in which
oil is accumulated is sensed, the outside air load of the condenser
is increased. Thus, the quantity of gas refrigerant circulating in
the cycle is increased. As the result of this operation, it is
possible to recover oil and prevent oil from being retained in the
second evaporator, and to deliver the intended capability of the
evaporator.
[0260] Therefore, the oil lubricity of the compressor can be
ensured, and breakage of the compressor, including seizure, can be
prevented.
[0261] With respect to the above-described 24th to 26th
embodiments, different controllable factors A are respectively
described. With respect to the 24th and 25th (or 26th) embodiments,
different means C are respectively described. Instead, the ejector
cycle system may be controlled by combining one or more specific
controllable factors A and another means C. More specific
description will be given. For example, the refrigerant temperature
difference and/or pressure loss (pressure drop) between the
refrigerant inlet and outlet of the second evaporator in the 25th
embodiment is adopted as the controllable factor A. With respect to
the determination condition B, the following operation is performed
at Step S3: when the refrigerant temperature difference and/or
pressure drop is out of the specified range, it is determined that
the operation is not normal, and the operation proceeds to Step S4.
Then, the means C is taken. The means C may be the operation in
which adjustment is made to reduce the opening of the variable
expansion valve 43 or the ejector 15 in the 24th embodiment.
Other Embodiments
[0262] The invention is not limited to the above-mentioned
embodiments, and various modifications can be made as described
later.
[0263] The above 1-23rd embodiments are examples in which the
invention is applied to refrigerator device for vehicles and the
space to be cooled with the first evaporator 16 and that with the
second evaporator 20 are identical. The space to be cooled with the
first evaporator 16 and that with the second evaporator 20 may be
separated from each other.
[0264] For example, the following construction may be adopted: the
space to be cooled with the first evaporator 16 is the front seat
area in a vehicle compartment and the space to be cooled with the
second evaporator 20 is the rear seat area in the vehicle
compartment. In cases where the spaces to be cooled are different
from each other, the following construction may be adopted: a
dedicated blower for evaporator is provided for each evaporator,
and the quantities of air sent by the blowers for evaporator are
individually controlled. Thus, the flow ratio .eta. may be adjusted
by adjusting the flow rate Gnoz of refrigerant that virtually
passes through the nozzle portion 15a of the ejector 15 and the
flow rate Ge of refrigerant drawn into the refrigerant suction port
15b of the ejector 15.
[0265] In the first to fourth, sixth to ninth, 11th to 14th, 16th
to 18th, and 20th to 23rd embodiments, a variable displacement
compressor is used for the compressor 11. Then, its electric
capacity control valve 11b is controlled by the air conditioning
controller 21, and the refrigerant discharge capability of the
compressor 11 is thereby controlled. Instead, the following
construction may be adopted: such a fixed displacement compressor
as the compressors 61 to 64 is used, and the ratio of the operating
state to the non-operation state (operating ratio) of the fixed
displacement compressor is controlled by the electromagnetic clutch
12a and 61a to 64a. The refrigerant discharge capability of the
compressor 11 and 61 to 64 is thereby controlled.
[0266] An electric compressor may be used for the compressor. In
this case, the refrigerant discharge capability can be controlled
by controlling the number of revolutions of the electric compressor
11.
[0267] The first, sixth, 11th, 16th, 20th, and 23rd embodiments use
the variable throttling mechanism 14 and 33, electric variable
throttling mechanism 36, and ejector with the area of the
refrigerant passage in its nozzle portion fixed. Instead, a
variable ejector whose nozzle opening is variable may be used to
adjust the refrigerant flow rate Gnoz. Specifically, the variable
ejector is an ejector provided with a passage area varying
mechanism that is capable of variably controlling the area of the
refrigerant passage in its nozzle portion according to external
signals. Use of a variable ejector also makes it possible to save
the space for the ejector cycle system.
[0268] In the fifth, 10th, 15th, 19th, and 22nd embodiments, the
number of revolutions of the electric motor 16b for driving is
controlled to adjust the quantity of air sent by the blower 16a for
evaporator. Instead, a passage opening adjusting mechanism that
adjusts the area of the passage through which air sent passes may
be used as the air quantity adjusting means to vary the quantity of
air. Specifically, a passage opening/closing door or the like
driven by a servo motor can be used for this purpose.
[0269] In the first to third embodiments, the degree of superheat
of refrigerant on the outlet side of the first evaporator 16 is
detected with the temperature sensitive cylinder and equalizing
pipe of the thermal expansion valve. In the fourth and fifth
embodiments, it is detected with the temperature sensor 51 and the
pressure sensor 52. The detecting means for the degree of superheat
of refrigerant on the outlet side of the first evaporator 16 is not
limited to them.
[0270] Some examples will be taken. It can be estimated from the
refrigerant evaporating temperature or pressure of the first
evaporator 16 and the temperature of refrigerant on the outlet side
of the first evaporator 16.
[0271] It can also be estimated from the refrigerant evaporating
temperature or pressure of the first evaporator 16 and the blown
air temperature of the first evaporator 16. This is because, when
the degree of superheat is increased, the cooling capacity of the
first evaporator 16 is lowered and the blown air temperature of the
first evaporator 16 is raised.
[0272] In addition, the degree of superheat can also be estimated
from the inlet air temperature of the first evaporator 16 and the
temperature of refrigerant on the outlet side of the first
evaporator 16. The degree of superheat can also be estimated from
the inlet air temperature of the first evaporator 16 and the blown
air temperature of the first evaporator 16.
[0273] The degree of superheat can also be estimated from only the
inlet air temperature of the first evaporator 16. The reason for
this is as follows: in cases where the air in a space to be cooled
(freezing chamber) is circulated and cooled in an evaporator as in
a refrigerator, the air temperature from the first evaporator 16
rises when the degree of superheat becomes too high. As a result,
the temperature in the freezing chamber rises, and thus the inlet
air temperature of the first evaporator 16 also rises.
[0274] Therefore, the degree of superheat of refrigerant on the
outlet side of the first evaporator 16 can also be detected using a
means for detecting the above-mentioned physical quantities.
[0275] In the sixth to eighth embodiments, the degree of superheat
of refrigerant on the outlet side of the second evaporator 20 is
detected with the temperature sensitive cylinder and equalizing
pipe of the thermal expansion valve. In the ninth and 10th
embodiments, it is detected with the temperature sensor 53 and the
pressure sensor 54. The detecting means for the degree of superheat
of refrigerant on the outlet side of the second evaporator 20 is
not limited to them.
[0276] Some examples will be taken. In the above description, the
degree of superheat of refrigerant on the outlet side of the first
evaporator 16 is detected. Similarly, it can be estimated from the
refrigerant evaporating temperature or pressure of the second
evaporator 20 and the temperature of refrigerant on the outlet side
of the second evaporator 20. In addition, it may be estimated from
the refrigerant evaporating temperature or pressure of the second
evaporator 20 and the blown air temperature of the second
evaporator 20.
[0277] The degree of superheat can also be estimated by other
methods. Such methods include estimation by: a combination of the
inlet air temperature of the second evaporator 20 and the
temperature of refrigerant on the outlet side of the second
evaporator 20; a combination of the inlet air temperature of the
second evaporator 20 and the blown air temperature of the second
evaporator 20; and only the inlet air temperature of the second
evaporator 20.
[0278] Therefore, the degree of superheat of refrigerant on the
outlet side of the second evaporator 20 can also be detected using
a means for detecting the above-mentioned physical quantities.
[0279] In the 11th to 15th and 20th to 22nd embodiments, the degree
of subcooling of refrigerant on the outlet side of the radiator 12
is detected with the temperature sensors 55 and 56. The detecting
means for the degree of subcooling of refrigerant on the outlet
side of the radiator 12 is not limited to them.
[0280] For example, it can be estimated from: a combination of the
refrigerant condensation temperature (refrigerant pressure) of the
radiator 12 and the temperature of refrigerant on the outlet side
of the radiator 12; a combination of the inlet air temperature of
the radiator 12 and the outlet refrigerant temperature of the
radiator 12; or the dryness of refrigerant on the outlet side of
the radiator 12.
[0281] Therefore, the degree of subcooling of refrigerant on the
outlet side of the radiator 12 can also be detected using a means
for detecting above-mentioned physical quantities.
[0282] In the first, second, sixth, seventh, 11th, 12th, 16th,
17th, and 20th to 23rd embodiments, the variable throttling
mechanism 14, 30, 31, 33, 34, and 35 and the electric variable
throttling mechanism 36, 37, 38, 39, and 40 are disposed as follows
to adjust the flow ratio .eta.: they are placed between the branch
portion Z and the ejector 15 and between the branch portion Z and
the second evaporator 20. A flow rate-variable three-way valve may
be used at the branch portion Z.
[0283] Specifically, a rotary valve-type variable flow rate
three-way valve driven by a stepping motor can be used. Thus, the
opening area on the ejector 15 side at the branch portion Z and the
opening area on the branch passage 18 side (second evaporator 20
side) can be simultaneously and continuously varied. This makes the
adjustment of flow ratio .eta. easier.
[0284] In the above embodiments, a thermal expansion valve is used
for the variable throttling mechanism 14, 30, 31, 33, 34, and 35,
and a flow control valve driven by a stepping motor is used for the
electric variable throttling mechanism 36, 37, 38, 39, 40, and 41.
Instead, a variable throttling mechanism in which multiple fixed
throttles different in characteristics are changed and used may be
used.
[0285] Or, the above-mentioned variable throttling mechanism,
electric variable throttling mechanism, and fixed throttle in the
above embodiments may be combined and used.
[0286] In the fifth, 10th, 15th, and 19th embodiments, the quantity
of air sent by the blower 16a for evaporator is adjusted by
controlling the number of revolutions of the electric motor 16b for
driving. The quantity of air sent by the blower 12a for radiator
may be adjusted by controlling the number of revolutions of the
electric motor 12b for driving with the air conditioning controller
21. Thus, the refrigerant discharge flow rate of the compressor and
the pressure of refrigerant on the downstream side of the radiator
12 can be virtually varied.
[0287] For example, when the quantity of air sent to the radiator
12 is reduced, the degree of subcooling is lowered. (In case of
supercritical cycle, a high pressure is raised.) Thus, the pressure
is raised upstream of the ejector 15. Therefore, the flow rate Gnoz
of refrigerant passing through the nozzle portion 15a of the
ejector 15 and the suction pressure of the refrigerant suction port
15b of the ejector 15 fluctuate. As a result, the flow rate Ge of
refrigerant drawn into the refrigerant suction port 15b of the
ejector 15 also fluctuates. That is, the flow ratio .eta.
fluctuates.
[0288] Consequently, the following measure may be taken:
fluctuation in flow ratio .eta. corresponding to the degree of
subcooling (high pressure) is stored beforehand in the air
conditioning controller 21; based on the degree of subcooling (high
pressure), the air conditioning controller 21 varies the applied
voltage V1 to control the flow ratio n so that it approaches the
optimum flow rate tmax.
[0289] The above embodiments use two evaporators, the first
evaporator 16 and the second evaporator 20. The number of
evaporators may be further increased, and three or more evaporators
may be used.
[0290] For example, the following construction may be adopted with
respect to the first embodiment: a second branch passage is
provided which connects the section between the internal heat
exchanger 17 and the fixed throttle 19 in the branch passage 18 and
the outlet of the first evaporator 16; and a fixed throttle and a
third evaporator are provided in the second branch passage.
[0291] In this case, the throttling opening of the fixed throttle
19 and that of the fixed throttle placed in the second branch
passage only have to be so set that the following is implemented:
the flow rate of refrigerant that passes through the variable
throttling mechanism 14 when the degree of superheat of refrigerant
on the outlet side of the first evaporator 16 becomes equal to a
predetermined value, the flow rate of refrigerant passing through
the fixed throttle 19, and the flow rate of refrigerant passing
through the fixed throttle placed in the second branch passage
enhance the cooling capacity Qer of the entire system.
[0292] The cycles in the above embodiments are examples of
subcritical cycles in which a high pressure does not exceed the
critical pressure of refrigerant. As described in connection with
the 11th embodiment, the invention may be applied to a
supercritical cycle in which a high pressure exceeds the critical
pressure of refrigerant.
[0293] In the invention, the flow ratio (.eta.), the refrigerant
flow rate of the entire cycle, the refrigerant discharge flow rate,
and the air quantity are adjusted based on the detection values of
detecting means. Instead, a number of these adjusting means may be
combined. For example, the following construction may be adopted: a
first variable throttling mechanism is provided between the branch
portion Z and the ejector 15; a second variable throttling
mechanism is provided in the branch passage 18 upstream of the
second evaporator 20; and the flow ratio .eta.is directly
controlled by controlling Gnoz and Ge.
[0294] In the above embodiments, an ejector cycle system of the
invention is applied to refrigerator device for vehicles. Instead,
it may be applied to a stationary refrigerator, stationary freezing
chamber, refrigeration system, or vapor compression cycle, such as
heat pump cycle for water heater.
[0295] In the above-described any embodiments, CO.sub.2 refrigerant
or HC refrigerant may be used as the refrigerant.
Chlorofluorocarbon is a generic name of organic compounds
comprising carbon, fluorine, chlorine, and hydrogen, and is widely
used as refrigerant.
[0296] Fluorocarbon refrigerant includes HCFC
(hydrochlorofluorocarbon) refrigerant, HFC (hydrofluorocarbon)
refrigerant, and the like. These refrigerants are designated as
alternatives for chlorofluorocarbon because they do not destroy the
ozone layer.
[0297] HC (hydrocarbon) refrigerant is refrigerant substances that
contain hydrogen and carbon and occur in nature. The HC refrigerant
includes R600a (isobutane), R290 (propane), and the like.
[0298] The 20th to 23rd embodiments are so constructed that rapid
cooling operation is performed when the user turns on the rapid
cooling switch 65. Instead, the same rapid cooling operation as in
the 20th to 22nd embodiments may be performed on the following
occasion: when the air conditioning controller 21 determines that
rapid cooling is required based on physical quantities related to
at least one of the state of refrigerant in the cycle and the space
to be cooled with the first evaporator 16 and the second evaporator
20.
[0299] Specifically, when the temperature of a space to be cooled
meets a predetermined condition, it is determined that rapid
cooling is necessary. Or, the necessity for rapid cooling may be
determined by estimating the temperature of a space to be cooled
from the state of refrigerant in the cycle.
[0300] FIGS. 29 and 30 show an embodiment that provides a low
evaporating temperature control in response to both a manual signal
and an automatic signal. FIG. 29 shows a system diagram indicating
a refrigeration cycle and an electronic control device. FIG. 30
shows a block diagram indicating several operational functions
provided by the electronic control device.
[0301] The manual signal module generates a manual signal that can
be obtained via a switch 65' (e.g., rapid cooling switch 65) as
described in the previous embodiments. The automatic signal module
includes at least one sensor and evaluating circuit or program to
generate an automatic signal if certain criterion is met. The
automatic signal can be obtained via a sensor or sensors. The
automatic signal may be obtained by a predetermined operational
calculation responsive to one or plurality of sensor signals.
[0302] The automatic signal includes two request signals indicative
of different requirements for the system. The first one is a rapid
cooling request. The rapid cooling request indicates that the
refrigerating system primarily needs lower temperature for cooling
air or goods such as air supplied to a compartment or foods to be
cooled. The rapid cooling request may be generated in response to
an abrupt increase of heat load.
[0303] In this embodiment, the system has a refrigerator box 67
cooled by the evaporators 16 and 20. The refrigerator box 67 has an
opening 68 and a door 69. The refrigerator box 67 is structured to
be loaded with a tray for making ice cubes. The evaporators 16 and
20 may be located separately in distanced or partitioned
compartment of the refrigerator box 67. For example, the evaporator
16 may be located in a cold compartment, and the evaporator 20 may
be located in a freezer compartment where the tray is loaded. The
system further includes a sensor 72 to detect an existence of the
tray and generate a signal if the tray is detected. For example,
the sensor 72 may be a weight sensor responsive to the tray filled
with water. If the sensor 72 detects the tray with water, it
generates a signal indicative of the rapid cooling request.
Alternatively, the sensor 72 may be or include a door position
sensor that generates the rapid cooling request when a period of
time for open door reaches a certain long time.
[0304] The other one of the automatic signal is a power save
request that can be obtained via a sensor or a predetermined
operational calculation. The power save request indicates that the
refrigerating system can be run with a power saving operation. The
power saving request may be generated in response to a decrease of
heat load. For example, the power saving request may be generated
in response to a stable condition of the refrigerating system. In
the case that the sensor 72 is the door position sensor, the power
saving request can be generated when a door open frequency is less
than a certain threshold level supposed to be night. Alternatively,
in a case that the sensor 72 is a temperature sensor responsive to
an interior temperature of the refrigerator box 67, the power
saving request is obtained when it is determined that the interior
temperature is stable in a predetermined low temperature range.
Further, the sensor 72 may be responsive to an exterior temperature
of the refrigerator box 67, and generates the power saving request
when the exterior temperature is stable within a predetermined low
temperature range.
[0305] The system further includes a sensor 74 attached on a motor
66a for driving a compressor 66. The sensor 74 detects a power
supplied to the motor 66a and a speed of rotation. The power save
request can be generated when the power supplied to the motor 66a
drops below a certain lower level supposed to be night or winter.
The power save request can be also generated when the speed drops
below a certain lower level for a predetermined time continuously.
Since the motor 66a is controlled to keep the refrigerator box 67
cold by a controller 71 (ECU), such a stable speed operation of the
motor 66a surely indicates that the refrigerating system can keep
cool condition even in a power saving operation.
[0306] In this specification, since the same low temperature
control is obtained, the power save request may be included in the
rapid cooling request, and the power save request may be called as
the rapid cooling request.
[0307] The controller 71 provides at least two controls (first and
second control modules). One of the first and second control
modules can be selected by a selector as shown in FIG. 30. A first
control module provides a higher temperature control in which an
evaporating temperature in one of the evaporators 16 and 20 is kept
relatively higher temperature by controlling actuators such as
valves 36. The higher temperature control is performed as a normal
control function for the system. A second control module provides a
lower temperature control to obtain a rapid cooling function. The
lower temperature control in this embodiment also obtains a power
save function that lowers a power consumption of the motor 66a. The
lower temperature control keeps the evaporating temperature in one
of the evaporators 16 and 20 relatively lower temperature by
controlling actuators such as valves 36. For example, the lower
temperature control keeps the evaporating temperature at least
lower than that provided by the higher temperature control obtained
by the first control module. The lower temperature control may
reduce the evaporating temperature from the temperature provided
before the lower temperature control is activated. In this
embodiment, the second control module at least reduces the
evaporating temperature in the evaporator 20 that primarily freezes
the compartment where the tray is loaded.
[0308] The manual signal and the automatic signal are supplied to a
selector module that selects and switches controls of the
refrigerating cycle. The selector shown in FIG. 30 activates the
second control module for a predetermined time from the manual
signal or automatic rapid cooling signal is obtained or until the
objective of rapid cooling is achieved. For example, the second
control module is continuously activated until the water turn into
the ice cubes. Then, the selector automatically deactivates the
second control module and activates the first control module. The
selector activates the second control module for a predetermined
time from the power save request is obtained or until the power
save request is lost. For example, the system may be operated by
the second control module during the night time.
[0309] The second control module lowers the evaporating temperature
by operating the actuator such as the valve 36. The second control
module decreases or closes an opening degree of the valve 36 to
make the evaporating temperature lower. Alternatively, the actuator
can be a valve capable of varying a flow ratio of flow amount Gnoz
and Ge. For example, the actuator of the cycle may include a needle
valve disposed in the nozzle 15e of the ejector 15. Further, the
actuator may include a valve instead of the valve 19. Further, the
actuator may include a valve disposed on an upstream side of the
branch Z.
[0310] The lower temperature control also reduces a flow amount of
refrigerant into the evaporators 16, 20, since the low temperature
control reduces the flow amount to the ejector 15. Meantime, since
a suction pressure of the compressor 66 reduces, circulating amount
through the compressor 66 is also reduced. If a discharging
capacity and rotational speed of the compressor 66 are constant,
the circulating amount and a compression ratio are main factors
that influence the compressor torque. Therefore, in case that the
circulating amount has greater influences than the compression
ratio, the lower temperature control may lower the compressor
torque and reduce power consumption. This power saving advantage
can be achieved for the system equipped with a motor driven
compressor such as a hermetic-sealed container type compressor.
[0311] Further, the second control module may decrease a flow
amount of air supplied to the evaporators 16 and 20 in addition to
or instead of the above described evaporating temperature lowering
methods. Further, the second control module may increase a
super-heat degree of the refrigerant in at least one of the
evaporators 16 and 20 in addition to or instead of the described
evaporating temperature lowering methods.
[0312] While the invention has been described with reference to
preferred embodiments thereof, it is to be understood that the
invention is not limited to the preferred embodiments and
constructions. The invention is intended to cover various
modification and equivalent arrangements. In addition, while the
various elements of the preferred embodiments are shown in various
combinations and configurations, which are preferred, other
combinations and configuration, including more, less or only a
single element, are also within the spirit and scope of the
invention.
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