U.S. patent application number 11/810523 was filed with the patent office on 2007-12-20 for refrigerant cycle device and heat-exchanger integrated unit with temperature sensor for the same.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Tomohiko Nakamura.
Application Number | 20070289318 11/810523 |
Document ID | / |
Family ID | 38859562 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289318 |
Kind Code |
A1 |
Nakamura; Tomohiko |
December 20, 2007 |
Refrigerant cycle device and heat-exchanger integrated unit with
temperature sensor for the same
Abstract
A refrigerant cycle device includes an ejector having a nozzle
portion for decompressing refrigerant and a refrigerant suction
port from which refrigerant is drawn by a high-speed refrigerant
stream jetted from the nozzle portion, and a refrigerant branch
passage branched from an upstream side of the nozzle portion in a
refrigerant flow such that refrigerant flows into the refrigerant
suction port through the refrigerant branch passage. Furthermore, a
first heat exchanger is disposed to evaporate refrigerant flowing
out of the ejector, a second heat exchanger is disposed in the
refrigerant branch passage to evaporate refrigerant, and a
temperature sensor is located to detect a temperature so as to
detect a frost in the second heat exchanger. In addition, a
controller performs a frost prevention control for reducing the
frost in the second heat exchanger, in accordance with the
temperature detected by the temperature sensor.
Inventors: |
Nakamura; Tomohiko;
(Obu-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: |
38859562 |
Appl. No.: |
11/810523 |
Filed: |
June 6, 2007 |
Current U.S.
Class: |
62/150 ; 62/278;
62/500 |
Current CPC
Class: |
F25B 41/00 20130101;
F25B 2500/18 20130101; F25B 5/00 20130101; F25B 2341/0011 20130101;
F25B 2700/21173 20130101; F25B 47/006 20130101; F25D 29/005
20130101 |
Class at
Publication: |
62/150 ; 62/278;
62/500 |
International
Class: |
F25D 21/00 20060101
F25D021/00; F25B 47/00 20060101 F25B047/00; F25B 1/06 20060101
F25B001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2006 |
JP |
2006-165106 |
Claims
1. A refrigerant cycle device comprising: a compressor for sucking
and compressing refrigerant; a radiator located to cool
high-pressure refrigerant discharged from the compressor; a
refrigerant adjusting unit located to adjust a refrigerant amount
flowing from the radiator to a downstream side such that a
super-heating degree of refrigerant to be sucked to the compressor
approaches to a predetermined degree; an ejector that includes a
nozzle portion for decompressing refrigerant flowing from the
refrigerant adjusting unit, and a refrigerant suction port from
which refrigerant is drawn by a high-speed refrigerant stream
jetted from the nozzle portion; a refrigerant branch passage that
is branched from an upstream side of the nozzle portion in a
refrigerant flow such that refrigerant flows into the refrigerant
suction port through the refrigerant branch passage; a first heat
exchanger disposed to evaporate refrigerant flowing out of the
ejector; a second heat exchanger disposed in the refrigerant branch
passage to evaporate refrigerant to be drawn into the refrigerant
suction port; a' temperature sensor located to detect a temperature
so as to detect a frost in the second heat exchanger; and a
controller which performs a frost prevention control to reduce the
frost in the second heat exchanger, in accordance with the
temperature detected by the temperature sensor.
2. The refrigerant cycle device according to claim 1, wherein: the
second heat exchanger includes a plurality of tubes in which
refrigerant flows, and upper and lower tanks located at upper and
lower sides of the plurality of tubes to distribute refrigerant
into or collect the refrigerant from the plurality of tubes; and
the temperature sensor is located at a predetermined position of
the second heat exchanger, at which refrigerant flows upwardly from
the lower tank.
3. The refrigerant cycle device according to claim 1, wherein the
first heat exchanger and the second heat exchanger are located to
perform heat exchange with a common heat-exchanging medium.
4. The refrigerant cycle device according to claim 3, wherein the
second heat exchanger is located downstream of the first heat
exchanger in a flow direction of the heat-exchanging medium such
that the heat-exchanging medium after passing through the first
heat exchanger passes through the second heat exchanger.
5. The refrigerant cycle device according to claim 1, wherein the
controller reduces a discharge capacity of refrigerant discharged
from the compressor during the frost prevention control.
6. The refrigerant cycle device according to claim 1, wherein the
controller stops operation of the compressor during the frost
prevention control.
7. The refrigerant cycle device according to claim 1, wherein the
temperature sensor is located to detect a temperature of air
immediately after passing through the second heat exchanger.
8. The refrigerant cycle device according to claim 2, wherein: the
second heat exchanger further includes a plurality of fins located
between the tubes; and the temperature sensor is located to detect
a temperature of one of the fins and the tubes.
9. The refrigerant cycle device according to claim 1, wherein the
predetermined position is close to the lower tank.
10. A heat-exchanger integrated unit for a refrigerant cycle
device, the integrated unit comprising: a heat exchanger for
evaporating refrigerant; an ejector that includes a nozzle portion
for decompressing refrigerant, and a refrigerant suction port from
which refrigerant from the heat exchanger is drawn by a high-speed
refrigerant flow jetted from the nozzle portion; and a temperature
sensor for detecting a temperature so as to detect a frost in the
heat exchanger, wherein the temperature sensor is located in the
heat exchanger at a predetermined position at which refrigerant
flows upwardly from below.
11. A heat-exchanger integrated unit for a refrigerant cycle device
that includes an ejector having a nozzle portion for decompressing
refrigerant, the integrated unit comprising: a first heat exchanger
located to perform heat exchange between refrigerant and a
heat-exchanging medium; a second heat exchanger located downstream
from the first heat exchanger in a flow direction of the
heat-exchanging medium to perform heat exchange between refrigerant
and the heat-exchanging medium flowing from the first heat
exchanger; and a temperature sensor located to detect a temperature
of the second heat exchanger so as to detect a frost in the second
heat exchanger, wherein: the first heat exchanger is located to
evaporate refrigerant flowing out of the ejector; and the second
heat exchanger has at least a suction-side heat exchanging portion
that is located to evaporate refrigerant to be drawn into a
refrigerant suction port of the ejector, from which refrigerant is
drawn into the ejector by a high-speed refrigerant stream jetted
from the nozzle portion.
12. The heat-exchanger integrated unit according to claim 11,
wherein: the second heat exchanger includes a plurality of tubes in
which refrigerant flows, and upper and lower tanks located at upper
and lower sides of the plurality of tubes to distribute refrigerant
into or collect the refrigerant from the plurality of tubes; and
the temperature sensor is located at a predetermined position of
the second heat exchanger, at which refrigerant flows upwardly from
the lower tank.
13. The heat-exchanger integrated unit according to claim 12,
wherein the ejector is located in the upper tank of the second heat
exchanger.
14. The heat-exchanger integrated unit according to claim 11,
further comprising: a throttle unit which is located at an upstream
side of a heat exchanging portion of the second heat exchanger in a
refrigerant flow, to decompress refrigerant while adjusting a
refrigerant flow amount supplied to the second heat exchanger,
wherein the throttle unit is integrated with the second heat
exchanger.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2006-165106 filed on Jun. 14, 2006, the contents of which are
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a refrigerant cycle device
that includes an ejector serving as refrigerant decompression means
and refrigerant circulation means, and a plurality of evaporators.
For example, the evaporator is suitable to an air conditioner for a
vehicle, or a refrigeration unit for a vehicle for freezing and
refrigerating goods mounted on the vehicle. More particularly, the
present invention relates to a heat-exchanger integrated unit with
a temperature sensor for a refrigerant cycle device having an
ejector.
BACKGROUND OF THE INVENTION
[0003] JP-A-2001-74388 (corresponding to U.S. Pat. No. 6,449,979)
discloses a refrigerant cycle device that includes a first
evaporator connected to a downstream side of an ejector, and a
second evaporator connected to a refrigerant suction port of the
ejector. In the refrigerant cycle device, an evaporation
temperature of refrigerant in the second evaporator is lower than
that in the first evaporator.
[0004] The first and second evaporators are adapted to cool a
common space to be cooled, and the first evaporator is disposed on
the upstream side in the flow direction of air, while the second
evaporator is disposed on the downstream side in the flow direction
of air. Thus, the refrigerant cycle device is constructed by
combining the first evaporator on the refrigerant downstream side
of the ejector and the second evaporator on the refrigerant suction
side of the ejector, thereby cooling the common space to be
cooled.
[0005] JP-A-2005-308384 (corresponding to US 2005/0268644 A1)
discloses an evaporator for allowing refrigerant to flow snaking
through tubes and tank portions which are arranged in the
evaporator in even rows in the flow direction of external
fluid.
[0006] Furthermore, in a conventional vapor-compression refrigerant
cycle device, when a load to be cooled is small and the temperature
of an evaporator is decreased, frost (frosting) occurs on the
evaporator. As a result, a cooling function is not performed
effectively. For this reason, a contact type fin temperature sensor
is inserted into an appropriate portion of a fin of the evaporator
to detect the surface temperature of the fin. Alternatively, a
non-contact type air temperature sensor is used to detect the
temperature of air on the post-evaporator side. In this case, a
compressor is intermittently operated so as to prevent the
formation of the frost on the evaporator.
[0007] However, the distribution of refrigerant and air velocity
always becomes nonuniform in the evaporator. In the conventional
method, the temperature sensor cannot be attached to any position
of the evaporator. At this time, the higher the temperature of a
detection point of the temperature sensor, the more the timing of
stopping the compressor is delayed, resulting in an excess amount
of supply of the refrigerant, which leads to frosting of the
evaporator. Accordingly, air cannot flow downwind smoothly due to
the frost, and thus the cooling cannot be performed sufficiently.
In this case, the air temperature sensor senses high air
temperature with the formation of the frost, and continues rotating
the compressor, which may lead to breakage of the cycle or failure
of the compressor. Although the fin temperature sensor can control
such a condition, the cycle cannot be activated until the frosted
part is melted, resulting in decrease in cooling operating
efficiency.
[0008] For this reason, an appropriate attachment position is
required to be determined by various tests for every type
evaporator such that the temperature sensor is attached to a
position where the fin temperature or blown-air temperature of the
evaporator becomes lowest.
SUMMARY OF THE INVENTION
[0009] In view of the foregoing problems, it is an object of the
present invention to provide a refrigerant cycle device in which a
frost prevention control can be effectively performed.
[0010] It is another object of the present invention to provide a
heat-exchanger integrated unit for a refrigerant cycle device, in
which a temperature sensor used for a frost prevention control can
be easily attached at a suitable position of a heat exchanger.
[0011] According to a first example of the present invention, a
refrigerant cycle device includes a compressor for sucking and
compressing refrigerant, a radiator located to cool high-pressure
refrigerant discharged from the compressor, a refrigerant adjusting
unit located to adjust a refrigerant amount flowing from the
radiator to a downstream side such that a super-heating degree of
refrigerant to be sucked to the compressor approaches to a
predetermined degree, an ejector that includes a nozzle portion for
decompressing refrigerant flowing from the refrigerant adjusting
unit and a refrigerant suction port from which refrigerant is drawn
by a high-speed refrigerant stream jetted from the nozzle portion,
a refrigerant branch passage that is branched from an upstream side
of the nozzle portion in a refrigerant flow such that refrigerant
flows into the refrigerant suction port through the refrigerant
branch passage, a first heat exchanger disposed to evaporate
refrigerant flowing out of the ejector, a second heat exchanger
disposed in the refrigerant branch passage to evaporate refrigerant
to be drawn into the refrigerant suction port, a temperature sensor
located to detect a temperature so as to detect a frost in the
second heat exchanger, and a controller which performs a frost
prevention control to reduce the frost in the second heat exchanger
in accordance with the temperature detected by the temperature
sensor. Accordingly, it is possible to reduce and prevent frost
generated on the second heat exchanger when being used as an
evaporator. Furthermore, because the refrigerant adjusting unit is
located to adjust a refrigerant amount flowing from the radiator to
a downstream side such that a super-heating degree of refrigerant
to be sucked to the compressor approaches to a predetermined
degree, operation efficiency of the refrigerant cycle device can be
effectively improved.
[0012] For example, the second heat exchanger includes a plurality
of tubes in which refrigerant flows, and upper and lower tanks
located at upper and lower sides of the plurality of tubes to
distribute refrigerant into or collect the refrigerant from the
plurality of tubes. In this case, the temperature sensor is located
at a predetermined position of the second heat exchanger, at which
refrigerant flows upwardly from the lower tank.
[0013] The controller can reduces a discharge capacity of
refrigerant discharged from the compressor during the frost
prevention control, or can stop operation of the compressor during
the frost prevention control. Furthermore, the temperature sensor
can be located to detect a temperature of air immediately after
passing through the second heat exchanger, or can be located to
detect a temperature of one of fins and tubes of the second heat
exchanger. Furthermore, the predetermined position may be set close
to the lower tank.
[0014] According to another example of the present invention, a
heat-exchanger integrated unit for a refrigerant cycle device
includes a heat exchanger for evaporating refrigerant, an ejector
that includes a nozzle portion for decompressing refrigerant and a
refrigerant suction port from which refrigerant from the heat
exchanger is drawn by a high-speed refrigerant flow jetted from the
nozzle portion, and a temperature sensor for detecting a
temperature so as to detect a frost in the heat exchanger.
Furthermore, the temperature sensor is located in the heat
exchanger at a predetermined position at which refrigerant flows
upwardly from below. Therefore, when the heat exchanger is used as
an evaporator, frost generated on the heat exchanger can be
suitably reduced by using the temperature detected by the
temperature sensor.
[0015] According to another example of the present invention, a
heat-exchanger integrated unit for a refrigerant cycle device
includes a first heat exchanger located to perform heat exchange
between refrigerant and a heat-exchanging medium, a second heat
exchanger located downstream from the first heat exchanger in a
flow direction of the heat-exchanging medium to perform heat
exchange between refrigerant and the heat-exchanging medium flowing
from the first heat exchanger, and a temperature sensor located to
detect a temperature of the second heat exchanger so as to detect a
frost in the second heat exchanger. Furthermore, the first heat
exchanger is located to evaporate refrigerant flowing out of an
ejector of the refrigerant cycle device, and the second heat
exchanger has at least a suction-side heat exchanging portion that
is located to evaporate refrigerant to be drawn into a refrigerant
suction port of the ejector, from which refrigerant is drawn into
the ejector by a high-speed refrigerant stream jetted from the
nozzle portion. Because the temperature sensor is located to detect
the temperature of the second heat exchanger having a refrigerant
temperature lower than that of the first heat exchanger, front can
be easily detected using the temperature sensor, thereby
effectively reducing and preventing front generated on the second
heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] 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:
[0017] FIG. 1 is a schematic diagram of an ejector-type refrigerant
cycle device of one embodiment to which the present invention is
applied;
[0018] FIG. 2 is a perspective view showing a schematic
construction of a heat-exchanger integrated unit for the
ejector-type refrigerant cycle device of FIG. 1;
[0019] FIG. 3 is a longitudinal sectional view of an upper tank
portion of the integrated unit of FIG. 2;
[0020] FIG. 4 is a lateral sectional view of a part of the upper
tank portion of the integrated unit of FIG. 2;
[0021] FIG. 5A is a perspective view of a fin temperature sensor,
and FIG. 5B is a partial sectional view showing the structure of a
sensor portion of the fin temperature sensor of FIG. 5A;
[0022] FIG. 6 is a perspective view of an air temperature
sensor;
[0023] FIG. 7 is a diagram of temperature distribution at a second
evaporator when being viewed from the downstream side of an air
flow;
[0024] FIG. 8 is a graph representing a relationship of a
refrigeration operating efficiency with respect to a flow ratio of
refrigerant passing through the second evaporator;
[0025] FIG. 9 is a schematic diagram of an ejector-type refrigerant
cycle device of a modified example of FIG. 1 of the present
invention;
[0026] FIG. 10 is a perspective view showing a heat-exchanger
integrated unit according to a first modified example of the
embodiment of the present invention;
[0027] FIG. 11 is a perspective view showing a heat-exchanger
integrated unit according to a second modified example of the
embodiment of the present invention;
[0028] FIG. 12 is a perspective view showing a heat-exchanger
integrated unit according to a third modified example of the
embodiment of the present invention; and
[0029] FIG. 13 is a perspective view showing a heat-exchanger
integrated unit according to a fourth modified example of the
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] Reference will now be made to preferred embodiments of an
ejector-type refrigerant cycle device and a heat-exchanger
integrated unit for the ejector-type refrigerant cycle device
according to the present invention.
[0031] In order to constitute the refrigerant cycle device
including an ejector, the heat-exchanger integrated unit is
connected to other components of the refrigerant cycle device,
e.g., a radiator and a compressor, via piping. The heat-exchanger
integrated unit of this example is used in applications for cooling
air to serve as indoor equipment. The heat-exchanger integrated
unit of another example can also be used as outdoor equipment.
[0032] In an ejector-type refrigerant cycle device 10 of the
embodiment, a compressor 11 for sucking and compressing refrigerant
is rotatably driven by an engine for vehicle running (not shown)
via an electromagnetic clutch 11a, a belt, and the like.
[0033] As the compressor 11, may be used either of a variable
displacement compressor for being capable of adjusting a
refrigerant discharge capacity depending on a change in compression
capacity, or a fixed displacement compressor for adjusting a
refrigerant discharge capacity by changing an operating efficiency
of the compressor by intermittent connection of an electromagnetic
clutch 11a. The electromagnetic clutch 11a shown in FIG. 1 is
controlled by an output from a controller (ECU, control means) 50
to be intermittently connected. When the compressor 11 is an
electric compressor, the compressor 11 can adjust its refrigerant
discharge capacity by adjustment of the number of revolutions of an
electric motor.
[0034] A radiator 12 (refrigerant cooler) is disposed on a
refrigerant discharge side of the compressor 11. The radiator 12
exchanges heat between high-pressure refrigerant discharged from
the compressor 11 and the outside air (i.e., air outside a vehicle
compartment) blown by a cooling fan not shown to cool the
high-pressure refrigerant. In this embodiment, refrigerant whose
high pressure does not exceed the critical pressure, such as a
Freon-based or HC-based refrigerant, is used to form a
vapor-compression subcritical cycle. In this case, the radiator 12
serves as a condenser for cooling and condensing the
refrigerant.
[0035] A liquid receiver 12a is provided at an outlet side of the
radiator 12. The liquid receiver 12a has a vertically oriented
tank-like shape to be well known, and serves as a liquid/vapor
separator for separating the refrigerant into liquid and vapor
phases to store the excess liquid refrigerant in the refrigerant
cycle. The liquid refrigerant is guided to flow out of the lower
part of the tank-shaped inside at the outlet of the liquid receiver
12a. The liquid receiver 12a is integrally formed with the radiator
12 in this example.
[0036] The radiator 12 may have the known structure including a
heat exchanging portion for condensation disposed on the upstream
side of refrigerant flow, the liquid receiver 12a for receiving
refrigerant introduced from the heat exchanging portion for
condensation to separate the refrigerant into liquid and vapor
phases, and a heat exchanging portion for supercooling of the
saturated liquid refrigerant from the liquid receiver 12a. A
thermal expansion valve 13 is disposed at an outlet side of the
liquid receiver 12a. The thermal expansion valve 13 serves as
adjustment means for adjusting an amount of the liquid refrigerant
from the liquid receiver 12a, and has a temperature sensing portion
13a disposed in a passage on the suction side of the compressor
11.
[0037] The thermal expansion valve 13 detects a degree of superheat
SH of the refrigerant on the suction side of the compressor 11
based on the temperature and pressure of the suction side
refrigerant of the compressor 11 (i.e., refrigerant on the outlet
side of the evaporator 15), and adjusts a degree of opening of its
valve (refrigerant flow amount) such that the degree of superheat
SH of the compressor suction-side refrigerant is a predetermined
value, as is known in general.
[0038] An ejector 14 is disposed at an outlet side of the thermal
expansion valve 13. The ejector 14 serves as decompression means
for decompressing the refrigerant, and also as refrigerant
circulation means (kinetic vacuum pump) for circulating the
refrigerant by a suction action (entrainment action) of a
refrigerant flow ejecting at high velocity.
[0039] The ejector 14 includes a nozzle portion 14a that decreases
the sectional area of passage of refrigerant having passed through
the expansion valve 13 (intermediate-pressure refrigerant) so as to
reduce the pressure of the refrigerant and to expand the
refrigerant. The ejector 14 also includes a refrigerant suction
port 14b that is arranged in the same space as a refrigerant
ejection port of the nozzle portion 14a so as to suck the
vapor-phase refrigerant from a second evaporator (a second heat
exchanger, a second heat exchanging portion) 18 to be described
later.
[0040] A mixing portion 14c is provided on a downstream side of the
nozzle portion 14a and the refrigerant suction port 14b to mix the
high-velocity refrigerant flow from the nozzle portion 14a with the
suction refrigerant drawn into the refrigerant suction port 14b
from the second evaporator 18. A diffuser portion 14d serving as a
booster (pressure-increasing portion) is arranged on the downstream
side of the refrigerant flow of the mixing portion 14c. The
diffuser portion 14d is formed in such a shape to gradually
increase the passage area of the refrigerant, and has an effect of
reducing the velocity of the refrigerant flow to increase the
refrigerant pressure, that is, an effect of converting the velocity
energy of the refrigerant to the pressure energy thereof.
[0041] A first evaporator 15 is connected to a refrigerant outlet
side of the diffuser portion 14d of the ejector 14, and a
refrigerant outlet of the first evaporator 15 is connected to the
refrigerant suction side of the compressor 11. In contrast, a
refrigerant branch passage 16 is branched from the inlet side of
the ejector 14 (i.e., an intermediate part between the outlet side
of the thermal expansion valve 13 and the inlet side of the nozzle
14a of the ejector 14). The refrigerant branch passage 16 has the
downstream side thereof connected to the refrigerant suction port
14b of the ejector 14. A point "zz" in FIG. 1 indicates a branch
point of the refrigerant branch passage 16.
[0042] A throttle unit 17 is disposed in the refrigerant branch
passage 16, and the second evaporator 18 is disposed on a
downstream side of the refrigerant flow away from the throttle unit
17. The throttle unit 17 is decompression means serving to exhibit
an adjustment effect of the refrigerant flow ratio into the second
evaporator 18. Specifically, the throttle unit 17 is constructed
of, for example, a capillary tube, or an orifice.
[0043] In this embodiment, the first and second evaporators 15 and
18 are assembled to a heat-exchanger integrated unit 20 with the
following structure. For example, the two evaporators 15 and 18 are
accommodated in an air conditioning case not shown, and a common
electric blower 19 blows air (i.e., air to be cooled) through an
air passage formed in the air conditioning case in the direction of
arrow. The blown air of the electric blower 19 is cooled by the two
evaporators 15 and 18. In this embodiment, air is a medium for heat
exchange. The electric blower 19 is an electric fan driven by a
motor 19a. The motor 19a is rotatably driven by a control voltage
output from the controller 50.
[0044] The cold air cooled by the two evaporators 15, 18 may be
blown into the common space to be cooled (not shown). Accordingly,
the common space can be cooled by the two evaporators 15, 18. When
the ejector-type refrigerant cycle device 10 of this embodiment is
used for a refrigerant cycle device for vehicle air conditioning, a
space in the compartment of the vehicle is the space to be cooled.
When the ejector-type refrigerant cycle device 10 of this
embodiment is used for a refrigerant cycle device for a freezer
car, a freezer and refrigerator space of the freezer car is a space
to be cooled.
[0045] The first evaporator 15, which is connected to a main flow
path on the downstream side of the ejector 14, is disposed on the
upstream side of the air flow, and the second evaporator 18, which
is connected to the refrigerant suction port 14b of the ejector 14,
is disposed on the downstream side of the air flow. A temperature
sensor 40, which will be described later, is disposed in the second
evaporator 18 on a downwind side to serve as a detection member for
detecting frost (frosting) occurring on the two evaporators 15, 18.
A temperature signal detected by the temperature sensor 40 is input
to the controller 50, whereby the control of frost prevention
(i.e., frost prevention control) is performed by the controller 50
according to the temperature signal as described later.
[0046] In this embodiment, the ejector 14, the first and second
evaporators 15, 18, the throttle unit 17, and the temperature
sensor 40 are assembled as one integrated unit 20 (heat-exchanger
integrated unit). Now, concrete examples of this integrated unit 20
will be described with reference to FIGS. 2 to 6. FIG. 2 is a
perspective view showing an outline of the entire structure of this
integrated unit 20 (20A). FIG. 3 is a longitudinal (lengthwise)
sectional view of the upper tank portions 15b, 18b of the first and
second evaporators 15, 18. FIG. 4 is a lateral sectional view of
the upper tank portion 18b of the second evaporator 18.
[0047] Now, an example of the integrated structure including the
two evaporators 15,18 will be explained with reference to FIG. 2.
In the example shown in FIG. 2, the two evaporators 15, 18 are
completely integrated as one heat exchanger structure. Thus, the
first evaporator 15 constitutes an upstream side area of the air
flow in the one heat exchanger structure, and the second evaporator
18 constitutes a downstream side area of the air flow in the one
heat exchanger structure.
[0048] The up, down, left, and right arrows in FIG. 2 respectively
indicate the following. That is, the side of the second evaporator
18 on which the ejector 14 is disposed corresponds to the up
direction, the side of the second evaporator 18 on which the
ejector 14 is not disposed corresponds to the down direction, the
upstream side of the nozzle portion 14a of the ejector 14
corresponds to the left direction, and the downstream side of the
diffuser portion 14d of the ejector 14 corresponds to the right
direction, when being viewed from the downstream side of the flow
direction of the blown air. The up, down, left, and right
directions in the following description are the same as those in
FIG. 2.
[0049] The first evaporator 15 and the second evaporator 18 have
the same basic structure, each including heat-exchange core portion
15a, 18a, and tank portions 15b, 15c, 18b, 18c positioned on both
up and down sides of the heat-exchange core portion 15a, 18a,
respectively. The heat-exchange core portion 15a, 18a include a
plurality of tubes 21 extending vertically. Between the plurality
of tubes 21, a passage is formed through which a heat-exchanged
medium, for example, air, passes in this embodiment. Fins 22 are
disposed between these tubes 21, and brazed to the tubes 21.
[0050] Each of the heat-exchange core portions 15a, 18a is
constructed of a laminated structure including the tubes 21 and the
fins 22. These tubes 21 and fins 22 are alternately laminated in
the lateral direction of the heat-exchange core portions 15a, 18a.
In another embodiment, a structure without fins 22 may be employed.
Although FIG. 2 shows only a part of the laminated structure
including the tubes 21 and the fins 22, the laminated structure
including the tubes 21 and the fins 22 may be formed over the
entire areas of the heat-exchange core portions 15a, 18a. The blown
air of the electric blower 19 passes through voids of the laminated
structure.
[0051] The tube 21 forms therein a refrigerant passage, and is
constructed of a flat tube having a flat section extending along
the air flow direction. The fin 22 is a corrugated fin formed by
bending a thin plate in a wave-like shape, and is connected to the
flat outer surface of the tube 21 to expand an air side
heat-transmission area. The tubes 21 of the heat-exchange core
portion 15a and the tubes 21 of the heat-exchange core portion 18a
respectively construct the refrigerant passages that are
independent from each other. The tank portions 15b, 15c on both up
and down sides of the first evaporator 15, and the tank portions
18b, 18c on both up and down sides of the second evaporator 18
construct the refrigerant passage spaces that are independent from
each other.
[0052] Both the up and down ends of the tube 21 of the
heat-exchange core portion 15a are inserted into the tank portions
15b and 15c on both up and down sides of the first evaporator 15.
The tank portions 15b and 15c have tube engagement holes not shown.
Both the up and down ends of the tube 21 are made in communication
with the inner spaces of the tank portions 15b, 15c. Similarly,
both up and down ends of the tube 21 of the heat-exchange core
portion 18a are inserted into the tank portions 18b and 18c on both
up and down sides of the second evaporator 18. The tank portions
18b and 18c have tube engagement holes not shown. Both the up and
down ends of the tube 21 are made in communication with the inner
spaces of the tank portions 18b, 18c.
[0053] Thus, the tank portions 15b, 15c, 18b, 18c on both the up
and down sides serve to distribute the refrigerant to the
respective tubes 21 of the heat-exchange core portions 15a, 18a,
and to collect the refrigerant stream from the tubes 21. The two
upper tank portions 15b and 18b as well as the two lower tank
portions 15c and 18c are adjacent to each other, and thus can be
formed integrally.
[0054] Alternatively, the two upper tank portions 15b and 18b, and
the two lower tank portions 15c and 18c may be constructed
independently in the integrated unit 20A(20). Aluminum which is a
metal having excellent thermal conductivity and brazing property is
suitable as specific materials of components of the evaporator,
including the tube 21, the fin 22, and the tank portions 15b, 15c,
18b, 18c. Each component is formed using the aluminum material, and
all components of the first and second evaporators 15 and 18 are
assembled and then connected integrally by brazing.
[0055] In this embodiment, the throttle unit 17 is constructed of
first and second connection blocks 23 and 24 of the refrigerant
passages shown in FIG. 3 and the capillary tube, and is integrally
assembled to the first and second evaporators 15 and 18 by brazing.
In contrast, because the ejector 14 has fine passages formed in the
nozzle portion 14a with high accuracy, if the ejector 14 is brazed,
the nozzle portion 14a may be thermally deformed due to the high
temperature in brazing (brazing temperature of aluminum: about 600
degrees). This cannot keep the shape and dimension of the passage
in the nozzle portion 14a according to a predetermined design.
[0056] Thus, in this embodiment, after integrally brazing the first
and second evaporators 15,18, the first and second connection
blocks 23, 24 and the throttle unit 17, the ejector 14 is assembled
to the integrally brazed member. The throttle unit 17 and the first
and second connection blocks 23, 24 are formed of aluminum
material, like the evaporator components.
[0057] The first connection block 23, as shown in FIG. 3, is brazed
and fixed to one end side in the longitudinal direction of each of
the upper tank portions 15b, 18b of the first and second
evaporators 15, 18. The first connection block 23 forms a
refrigerant inlet 25 and a refrigerant outlet 26 of the integrated
unit 20 shown in FIG. 1. The refrigerant inlet 25 is branched into
a main passage 25a serving as a first passage directed to the inlet
side of the nozzle 14a of the ejector 14, and the branch passage 16
serving as a second passage directed to the inlet side of the
throttle unit 17 at a point (e.g., midpoint) of the first
connection block 23 in the thickness direction of the first
connection block 23.
[0058] The branch passage 16 of the first connection block 23
corresponds to an inlet part of the branch passage16 shown in FIG.
1. Therefore, the branch point z of FIG. 1 is located inside the
first connection block 23. In contrast, the refrigerant outlet 26
is constructed by one simple passage hole (a circular hole and the
like) penetrating through the first connection block 23 in the
thickness direction. The branch passage 16 of the first connection
block 23 is tightly connected to one end of the throttle unit 17
(left end shown in FIGS. 2 and 3) by brazing.
[0059] The second connection block 24 is disposed substantially at
a center area in the longitudinal direction of the inner space of
the upper tank portion 18b of the second evaporator 18, and brazed
to the inner wall surface of the upper tank portion 18b. This
second connection block 24 is located to partition the inner space
of the upper tank portion 18b into two spaces in the tank
longitudinal direction, that is, a left space 27 and a right space
28. The other end (right end) of the throttle unit 17 penetrates a
support hole 24a of the second connection block 24 to be opened in
the right space 28 of the upper tank portion 18b, as shown in FIG.
3.
[0060] An interface between the outer peripheral surface of the
throttle unit 17 and the support hole 24a is sealed by brazing with
an interface between both left and right spaces 27 and 28 being
shut down. Among the ejector 14, the nozzle portion 14a is made of
stainless, brass, or the like, and parts other than the nozzle
portion 14a (including a housing portion forming the refrigerant
suction port 14b, the mixing portion 14c, the diffuser portion 14d,
and the like) is made of metal material, such as copper or
aluminum, but may be made of resin (non-metallic material).
[0061] After the completion of integrated assembly of the first and
second evaporators 15 and 18 by brazing (brazing step), the ejector
14 is inserted into the upper tank portion 18b through the
refrigerant inlet 25 and a hole of the main passage 25a of the
first connection block 23. The inserted tip end in the longitudinal
direction of the ejector 14 corresponds to an outlet portion of the
diffuser portion 14d shown in FIG. 1. The tip end of the ejector is
inserted into a circular recess 24b of the second connection block
24, and gas-tightly fixed in the circular recess 24b using an
O-ring 29a.
[0062] The tip end of the ejector is in communication with a
communication hole 24c of the second connection block 24. A
partition plate 30 is disposed substantially at a center area in
the longitudinal direction of the inner space of the upper tank
portion 15b of the first evaporator 15. The inner space of the
upper tank portion 15b is partitioned by the partition plate 30
into two spaces in the longitudinal direction, that is, a left
space 31 and a right space 32. The communication hole 24c of the
second connection block 24 is in communication with the right space
32 of the upper tank portion 15b of the first evaporator 15 via a
through hole 33a of an intermediate wall surface 33 of both the
upper tank portions 15b, 18b.
[0063] The left end of the ejector 14 in the longitudinal direction
(left end of FIG. 3) corresponds to an inlet portion of the nozzle
portion 14a shown in FIG. 1, and is fitted into and fixed to the
inner wall surface of the main passage 25a of the first connection
block 23 using the O-ring 29b to be sealed therebetween. Fixing of
the ejector 14 in the longitudinal direction may be performed
using, for example, screw fixing means not shown. The O-ring 29a is
held in a groove (not shown) of the second connection block 24, and
the O-ring 29b is held in a groove (not shown) of the first
connection block 23.
[0064] In the first connection block 23, the refrigerant outlet 26
is formed to be in communication with the left space 31 of the
upper tank portion 15b, and the main passage 25a is formed to be in
communication with the left space 27 of the upper tank portion 18b.
The first connection black 23 is brazed to the side walls of the
upper tank portions 15b, 18b such that the branch passage 16 is
made in communication with one end of the throttle unit 17. The
refrigerant suction port 14b of the ejector 14 is set in
communication with the left space 27 of the upper tank portion 18b
of the second evaporator 18.
[0065] In this embodiment, the second connection block 24
partitions the inside of the upper tank portion 18b of the second
evaporator 18 into left and right spaces 27 and 28. The left space
27 serves as a collecting tank for collecting the refrigerant from
the plurality of tubes 21, and the right space 28 serves as a
distribution tank for distributing the refrigerant into the tubes
21. The ejector 14 has an elongated cylindrical shape extending in
an axial direction of the nozzle portion 14a, and the longitudinal
direction of the elongated cylindrical shape is made to correspond
to the longitudinal direction of the upper tank portion 18b, so
that the ejector 14 is elongated in parallel with the upper tank
portion 18b.
[0066] Thus, the ejector 14 and the evaporator 18 can be disposed
in a compact manner, and further the entire unit can be made
compact. The ejector 14 is disposed in the left space 27 serving as
the collecting tank of the evaporator 18, and has the refrigerant
suction port 14b set to be directly opened in the left space 27
serving as the collecting tank. This structure further can decrease
the number of refrigerant pipes.
[0067] This example has an advantage in that the collection of the
refrigerant from the plurality of tubes 21 and the supply of the
refrigerant to the ejector 14 (suction of the refrigerant) can be
performed only using one tank. The first evaporator 15 is disposed
adjacent to the second evaporator 18, and the ejector 14 is set
such that the downstream side end of the ejector 14 is adjacent to
the distribution tank of the first evaporator 15 (i.e., the right
space 32 of the upper tank portion 15b).
[0068] Thus, even when the ejector 14 is disposed to be
incorporated into the tank portion on the second evaporator 18
side, the outflow refrigerant from the ejector 14 can be supplied
to the first evaporator 15 side through a short simple refrigerant
passage (including holes 24c and 33a). The refrigerant flow path of
the entire integrated unit 20 with the above-mentioned structure
will be described below with reference to FIGS. 2 and 3.
[0069] The refrigerant inlet 25 of the first connection block 23 is
branched into the main passage 25a and the branch passage 16 within
the first connection block 23. First, the refrigerant from the main
passage 25a is decompressed through the ejector 14 (the nozzle
portion 14a, the mixing portion 14c, and the diffuser portion 14d,
in this order), and the low-pressure refrigerant decompressed flows
into the right space 32 of the upper tank portion 15b of the first
evaporator 15 as indicated by the arrow "aa" through the connection
hole 24c of the second connection block 24 and the through hole 33a
of the intermediate wall surface 33.
[0070] The refrigerant from the right space 32 flows through the
plurality of tubes 21 on the right side of the heat-exchange core
portion 15a as indicated by the arrow "bb" to flow into the right
side part of the lower tank portion 15c. Since no partition plate
is provided in the lower tank portion 15c, the refrigerant from the
right side part of the lower tank portion 15c moves to the left
side thereof as indicated by the arrow "cc".
[0071] The refrigerant from the left side part of the lower tank
portion 15c rises through the plurality of tubes 21 on the left
side of the heat-exchange core portion 15a as indicated by the
arrow "dd" to flow into the left space 31 of the upper tank portion
15b, and then to the refrigerant outlet 26 of the first connection
block 23 as indicated by the arrow "ee". In contrast, the
refrigerant from the branch passage 16 of the first connection
block 23 is first decompressed through the throttle unit 17, and
the decompressed low-pressure refrigerant flows into the right
space 28 of the upper tank portion 18b of the second evaporator 18
as indicated by the arrow "ff".
[0072] The refrigerant from the right space 28 flows through the
plurality of tubes 21 on the right side of the heat-exchange core
portion 18a as indicated by the arrow "gg" to flow into the right
portion of the lower tank portion 18c. Since no partition plate is
provided in the lower tank portion 18c, the refrigerant from the
right side part of the lower tank portion 18c moves to the left
side thereof as indicated by the arrow "hh".
[0073] The refrigerant from the left side part of the lower tank
portion 18c rises through the plurality of tubes 21 on the left
side of the heat-exchange core portion 18a as indicated by the
arrow "ii" to flow into the left space 27 of the upper tank portion
18b. The refrigerant suction port 14b of the ejector 14 is opened
in the left space 27, and thus the refrigerant in the left space 27
is drawn from the refrigerant suction port 14b into the ejector 14.
Since the integrated unit 20 has the refrigerant flow path
structure as described above, only one refrigerant inlet 25 may be
provided at the first connection block 23 in the entire integrated
unit 20, and only one refrigerant outlet 26 may be provided at the
first connection block 23.
[0074] The integrated unit 20 of the embodiment includes the
temperature sensor 40 integrally provided in the heat-exchange core
portion 18a of the second evaporator 18 on the downwind side, for
detecting the frost on the first and second evaporators 15, 18. The
temperature sensor 40 may be a contact type fin temperature sensor
40A for detecting the temperature of fins (evaporator), or a
non-contact type air temperature sensor 40B for detecting the
blown-air temperature on the post-evaporator flow side. The sensor
40 (40A, 40B) can be located at a suitable position in the
integrated unit 20.
[0075] FIG. 5A is a perspective view of the fin temperature sensor
40A, and FIG. 5B is a diagram showing the structure of a sensor
portion 42. FIG. 6 is a perspective view of the air temperature
sensor 40B. The structure of the fin temperature sensor 40A will be
described below. The fin temperature sensor 40A includes a sensor
portion 42 disposed on one end of a lead wire 43 and inserted into
a fin portion of the evaporator, and a resin clamp 41 having an
anchor portion 41a inserted into and fixed to the fin portion
together with the sensor portion 42, while holding the root side of
the sensor portion 42.
[0076] As shown in FIG. 5B, the sensor portion 42 includes a
temperature sensing semiconductor 42a whose resistance value
changes depending on the temperature of the tip end of the lead
wire 43 and which is connected to the tip end of the lead wire 43.
The sensor portion 42 also includes an epoxy resin 42b or the like
fixed to the periphery of the temperature sensing semiconductor
42a, and a conductive filler filling a gap in the sensor portion
42. These elements constituting the sensor portion 42 are inserted
into an aluminum case 42c (made of A1000 aluminum). The lead wire
43 is derived so as to output the resistance value of the sensor
portion 42 to a controller as an electric signal. A connector 44 is
connected to the other end of the lead wire 43 for connection with
the electric circuit.
[0077] As shown in FIG. 6, the air temperature sensor 40B is
constructed of a sensor portion 42, lead wire 43, and a connector
44. The sensor portion 42 includes a temperature sensing
semiconductor 42a connected to the tip end of the lead wire 43 and
the epoxy resin 42b or the like fixed to the periphery of the
semiconductor 42a. The air temperature sensor 40B has a support
part near the sensor portion 42 supported by the resin clamp 41.
Either sensor 40 (40A, 40B) is integrally fixed to the heat
exchange core portion of the integrated unit 20 by inserting the
anchor portion 41a of the clamp 41 into the fin portion at the
appropriate part of the integrated unit 20. In the fin temperature
sensor 40A of FIG. 5A, the sensor portion 42 protrudes in the same
direction as the anchor portion 41a for the attachment. That is,
the sensor portion 42 is held by the resin clamp 41 approximately
in parallel with the protruding direction of the anchor portion
41a. In contrast, in the air temperature sensor 40B of FIG. 6, the
sensor portion 42 protrudes in an extending line of the lead wire
43 to be approximately perpendicular to the protruding direction of
the anchor portion 41a for the attachment.
[0078] FIG. 7 is a diagram showing temperature distribution of the
second evaporator 18 when being viewed from the downstream side of
the air flow (inlet air temperature: 10 degrees, relative humidity:
80% RH). FIG. 7 shows that unevenness of the temperature
distribution occurs at a part in which the refrigerant stream flows
from the lower tank portion 18c. In particular, the refrigerant is
suspended (stopped) in the lower tank portion 18c (on the left side
of the embodiment), which has the lowest temperature (e.g.,
temperature T equal to or lower than 2.5.degree. C.) in the second
evaporator 18 on the lower temperature side, as shown in FIG.
7.
[0079] This tendency is common to a modified example to be
described later in which a refrigerant flow path pattern is changed
in the integrated unit 20. In this embodiment, a part MC in which
the refrigerant stream rises up and flows from the lower tank
portion 18c of the second evaporator 18 (see FIGS. 2 and 7) is used
as an appropriate attachment position in which the above-mentioned
temperature sensor 40 (40A or 40B) is set.
[0080] The part MC is a part in which the refrigerant flows from
the lower side of the heat exchange core portion of the evaporator
18 to the upper side thereof. When a plurality of parts MC, in
which the refrigerant flows from the lower side to the upper side
thereof, are provided in the evaporator serving as a heat
exchanging portion disposed on the suction side of the ejector 14,
the temperature sensor 40 can be provided in a position where the
frost is observed at the most early stage. For example, the
temperature sensor 40 can be positioned nearest to the ejector 14
in the plurality of MC parts.
[0081] Reference will now be made to an operation of the
refrigerant cycle device of the embodiment. When the compressor 11
is driven by the engine for vehicle running, the high-temperature
and high-pressure refrigerant compressed and discharged by the
compressor 11 flows into the radiator 12. The high-temperature
refrigerant is cooled and condensed by the outside air in the
radiator 12. The high-pressure refrigerant flowing from the
radiator 12 flows into the liquid receiver 12a, in which the
refrigerant is separated into liquid and vapor phases. The liquid
refrigerant is fed from the liquid receiver 12a to pass through the
expansion valve 13.
[0082] The expansion valve 13 has a valve opening degree
(refrigerant flow amount) adjusted such that a degree of superheat
SH of the refrigerant at the outlet of the first evaporator 15
(refrigerant drawn into the compressor) is a predetermined value to
decompress the high-pressure refrigerant. The refrigerant having
passed through the expansion valve 13 (intermediate pressure
refrigerant) flows into the refrigerant inlet 25 provided in the
first connection block 23 of the integrated unit 20.
[0083] The refrigerant stream from the refrigerant inlet 25 is
divided into a refrigerant flow directed from the main passage 25a
of the first connection block 23 to the ejector 14, and a
refrigerant flow directed from the refrigerant branch passage 16 of
the first connection block 23 to the throttle unit 17. The
refrigerant entering the nozzle portion 14a of the ejector 14 is
decompressed and expanded by the nozzle portion 14a. Thus, the
pressure energy of the refrigerant is converted to the velocity
energy thereof at the nozzle portion 14a. The refrigerant from an
ejection port of the nozzle portion 14a is ejected at high
velocity.
[0084] The decrease in refrigerant pressure around the ejection
port sucks the refrigerant (vapor-phase refrigerant) having passed
through the second evaporator 18 of the branch refrigerant passage
16 from the refrigerant suction port 14b. The refrigerant ejected
from the nozzle portion 14a and the refrigerant drawn into the
refrigerant suction port 14b are mixed by the mixing portion 14c
positioned on the downstream side of the nozzle portion 14a to flow
into the diffuser portion 14d. The velocity (expansion) energy of
the refrigerant is converted to the pressure energy thereof by
enlarging the passage area in the diffuser portion 14d, resulting
in an increased pressure of the refrigerant.
[0085] The refrigerant flowing out of the diffuser portion 14d of
the ejector 14 flows through refrigerant flow paths of the first
evaporator 15 as indicated by the arrows "aa" to "ee" of FIG. 2.
During this time, the low-temperature and low-pressure refrigerant
absorbs heat from the blown air to be evaporated in the
heat-exchange core portion 15a of the first evaporator 15. The
evaporated vapor-phase refrigerant from the refrigerant outlet 26
is drawn into the compressor 11, and compressed again.
[0086] In contrast, the refrigerant flow entering the refrigerant
branch passage 16 is decompressed by the throttle unit 17 to be
low-pressure refrigerant, which flows through the refrigerant flow
paths of the second evaporator 18 as indicated by the arrows "ff"
to "ii" of FIG. 2. During this time, in the heat-exchange core
portion 18a of the second evaporator 18, the low-temperature and
low-pressure refrigerant absorbs heat from the blown air having
passed through the first evaporator 15 so as to be evaporated. The
vapor-phase refrigerant after evaporation is drawn from the
refrigerant suction port 14b into the ejector 14.
[0087] As mentioned above, according to this embodiment, the
refrigerant on the downstream side of the diffuser portion 14d of
the ejector 14 can be supplied to the first evaporator 15, while
the refrigerant on the refrigerant branch passage 16 side can be
supplied to the second evaporator 18 through the throttle unit 17a,
so that both the first and second evaporators 15 and 18 can exhibit
the cooling effect at the same time. Thus, the cold air cooled by
both the first and second evaporators 15 and 18 is blown off into a
space to be cooled, thereby refrigerating (cooling) the space.
[0088] At this time, the refrigerant evaporation pressure of the
first evaporator 15 is a pressure of the refrigerant whose pressure
is increased by the diffuser portion 14d. In contrast, because the
refrigerant outlet side of the second evaporator 18 is connected to
the refrigerant suction port 14b of the ejector 14, the lowest
pressure directly after the decompression by the nozzle portion 14a
can be applied to the second evaporator 18.
[0089] Thus, the refrigerant evaporation pressure (refrigeration
evaporation temperature) of the second evaporator 18 can be made
lower than that of the first evaporator 15. The first evaporator 15
whose refrigerant evaporation temperature is higher is disposed on
the upstream side with respect to the flow direction of the blown
air, while the second evaporator 18 whose refrigerant evaporation
temperature is lower is disposed on the downstream side in air
flow. In this case, both a difference between the refrigerant
evaporation temperature of the first evaporator 15 and the
temperature of air flowing into the first evaporator 15, and also a
difference between the refrigerant evaporation temperature of the
second evaporator 18 and the temperature of air flowing into the
second evaporator 18 can be ensured.
[0090] Thus, both the first and second evaporators 15 and 18 can
effectively exhibit cooling capacities. Therefore, the cooling
capacity for the common space to be cooled can be improved
effectively by the combination of the first and second evaporators
15 and 18. The suction pressure of the compressor 11 can be
increased by a pressure increasing effect of the diffuser portion
14d thereby decreasing a driving power of the compressor 11.
[0091] The refrigerant flow amount of the second evaporator 18 can
be adjusted independently by the throttle unit 17 without depending
on the function of the ejector 14, so that the refrigerant flow
amount flowing into the first evaporator 15 can be adjusted by a
throttle function of the ejector 14. This can facilitate adjustment
of the refrigerant flow amounts flowing into the first and second
evaporators 15 and 18 according to respective thermal loads.
[0092] Under the condition of a small cycle thermal load, a
difference in pressure of the refrigerant cycle is decreased, so
that the refrigerant flow amount of the ejector 14 becomes small.
In this embodiment, the refrigerant having passed through the
expansion valve 13 is branched at the upstream part of the nozzle
portion 14a of the ejector 14, and the branched refrigerant is
drawn into the refrigerant suction port 14b through the refrigerant
branch passage 16. The refrigerant branch passage 16 is in parallel
connection with the nozzle portion 14a of the ejector 14.
[0093] Thus, the refrigerant can be supplied to the refrigerant
branch passage 16 using not only the refrigerant suction capacity
of the ejector 14, but also the refrigerant suction and discharge
capacities of the compressor 11. This can reduce the degree of
decrease in refrigerant flow amount on the second evaporator 18
side even when the refrigerant flow amount flowing into the nozzle
portion 14a of the ejector 14 decreases. Thus, even under the
condition of the low thermal load, the cooling capacity of the
second evaporator 18 can be ensured easily.
[0094] Reference will now be made to the control of prevention of
frost (frosting) by the above-mentioned structure. When the
refrigeration capacity of the refrigerant cycle device exceeds the
cooling load, the refrigeration evaporation pressure in the
evaporator decreases, so that the evaporator air-side surface
temperature is below the freezing point (0.degree. C.). The
freezing of condensed water on the evaporator proceeds to interfere
with the flow of passing air in the evaporator, further leading to
a decrease in evaporation pressure of the refrigerant. To prevent
such problems, the refrigeration capacity of the refrigerant cycle
device is controlled to prevent the frost on the evaporator.
[0095] In this embodiment, ON-OFF control of a compressor 11 may be
performed as this control method. The ON-OFF control involves
turning off the compressor 11 when a refrigerant evaporation
temperature becomes below the freezing point. This control is the
most common method for frost prevention. Specifically, a fin
temperature or a blown-air temperature of the integrated unit 20 is
detected by the above-mentioned temperature sensor 40 (40A, 40B).
Then, electric current supplied to the electromagnetic clutch 11a
is turned off by the clutch 11a when the detected fin temperature
or blown-air temperature is lowered to 3.degree. C., for example.
In contrast, the clutch 11a is turned on again when the detected
fin temperature or blown-air temperature is increased to 4.degree.
C., for example. In the use of a variable displacement compressor
or an electric compressor as the compressor, the compressor
capacity control for controlling a discharge capacity of the
compressor can be performed so as to reduce the frost.
[0096] In the embodiment of the present invention, the expansion
valve 13 is provided for adjusting the flow amount of refrigerant
on the downstream side of the radiator 12 such that a degree of
superheat SH is a predetermined value (predetermined range). The
superheat degree SH is represented by a difference between the
superheat temperature and the saturation temperature of the
refrigerant at the outlet of the first evaporator 15. This adjusts
the refrigerant flow amount into the second evaporator 18 on the
low-temperature side to an appropriate value. As a result, frost on
the second evaporator 18 can be detected and determined by the
temperature sensor 40 so as to perform the frost prevention
control. This can reduce the frost in the second evaporator 18
and/or prevent the frost from being formed on the first and second
evaporators 15 and 18 due to the excessive supply of the
refrigerant, thereby improving the operating ratio of the
refrigerant cycle.
[0097] FIG. 8 is a graph showing a relationship of a refrigeration
operating efficiency with respect to a flow amount of refrigerant
passing through the second evaporator 18. Here, the refrigeration
operating efficiency is represented by a relationship of a stopped
time period of the refrigerant cycle due to the detection of the
temperature sensor 40, with respect to a cycle operating time on
the same air condition. In FIG. 8, the refrigerant flow ratio is a
ratio of the refrigerant amount flowing into the second evaporator
18 to the total refrigerant amount in the refrigerant cycle. Note
that the operating efficiency of the conventional cycle is set to
100 in FIG. 8.
[0098] Generally, the decrease in total refrigerant flow amount in
the evaporator 18 improves resistance to frost, but inevitably
leads to a decrease in cooling performance. In the embodiment, the
cooling operation property can be improved effectively over the
entire range of flow amounts of the refrigerant passing through the
second evaporator 18. The smaller the cooling load (that is, the
lower the air temperature and humidity), or/and the smaller the
thermal capacity of air to be heat exchanged, the smaller the
necessary refrigerant amount. This causes excessive refrigerant on
the side of the second evaporator18, so that the great cooling
effect can be obtained in a cooling load range of 5 to 50.degree.
C. of air temperature and in a range of 20 to about 100% of
relative humidity.
[0099] In this embodiment, the temperature sensor 40 is disposed at
the part MC where the refrigerant flows upwardly from the lower
tank portion 18c of the second evaporator 18. This is based on
findings that the lowest temperature area is the part MC in which
the refrigerant flows upwardly from the lower tank portion 18c in
the second evaporator 18. Accordingly, determination of an
attachment position of the temperature sensor 40 can be easily
performed during the control of frost prevention. As shown in FIG.
7, the part MC is a lower area of the core portion of the second
evaporator 18, close to the lower tank portion 18c.
[0100] The first evaporator 15 and the second evaporator 18 are
adapted to cool the air, which serves as a common heat-exchange
medium. The first evaporator 15 and the second evaporator 18 are
disposed so as to exchange heat between the refrigerant of the
second evaporator 18 and the air after being heat-exchanged with
the refrigerant of the first evaporator 15. Because the temperature
of the second evaporator 18 generally becomes lower, the air
flowing from the first evaporator 15 can be effectively cooled.
[0101] The ejector-type refrigerant cycle device includes the
ejector 14 for sucking the refrigerant from the refrigerant suction
port 14b by the high-velocity refrigerant stream ejecting from the
nozzle portion 14a, which is adapted to decompress and expand the
refrigerant. The refrigerant cycle device also includes the second
evaporator 18 (heat exchanging portion) for evaporating the
refrigerant to be drawn into the refrigerant suction port 14b. The
refrigerant cycle device further includes the temperature sensor 40
disposed at the part MC of the second evaporator 18, in which the
refrigerant flows from the lower side to the upper side to detect
the frost of the second evaporator 18.
[0102] Thus, the integrated construction of the ejector 14, the
second evaporator 18 and the temperature sensor 40 can be handled
as an integrated unit, thereby improving the handling properties in
delivery and assembly. The reason why the temperature sensor 40 is
provided at the part of the second evaporator 18, at which the
refrigerant rises up and flows from the lower side to the upper
side is the following. The lowest temperature area of the second
evaporator 18 is found to be the part MC where the refrigerant flow
rises up and flows from the lower tank portion 18c, as described
above. Thus, in the ejector-type refrigerant cycle device, the
temperature sensor 40 can be attached to an optimal position of the
second evaporator 18, for control of the frost prevention.
[0103] The ejector-type refrigerant cycle device includes the first
evaporator 15 disposed on the upstream side of the air flow, the
second evaporator 18 disposed on the downstream side of the air
flow with respect to the first evaporator 15, and the temperature
sensor 40 for determining the frost. The first evaporator 15 allows
the outflow refrigerant from the ejector 14 to evaporate, and the
second evaporator 18 allows the refrigerant on the suction port
side to be drawn into the refrigerant suction port 14b of the
ejector 14 to evaporate. The temperature sensor 40 is disposed in
the second evaporator 18.
[0104] Thus, the first and second evaporators 15 and 18, and the
temperature sensor 40 can be integrally formed to be handled as an
integrated unit, thereby improving the handling properties in
delivery and assembly. The reason why the temperature sensor 40 is
disposed in the second evaporator 18 is that the temperature of the
second evaporator 18 is lower than the temperature of the first
evaporator 15.
[0105] Furthermore, the temperature sensor 40 is disposed at the
part MC in which the refrigerant flow rises up and the refrigerant
flows from the lower tank portion 18c of the second evaporator 18.
This is because the lowest temperature area is positioned at the
part MC of the second evaporator 18 on the lower side in which the
refrigerant flows upwardly from the lower tank portion 18c.
Accordingly, the temperature sensor 40 can be attached to an
optimal position, such that the control of frost prevent for the
second evaporator 18 can be suitably performed.
[0106] In the above-described embodiment, the ejector 14 disposed
on the upstream side of the refrigerant flow of the first
evaporator 15, and the throttle unit 17 disposed on the upstream
side of the refrigerant flow of the second evaporator 18 are
integrally mounted on the first evaporator 15 and the second
evaporator 18. However, any one of the ejector 14 and the throttle
unit 17 may be integrally mounted on the first and second heat
exchangers 15 and 18, which are relatively large, so as to
construct the integrated unit 20.
[0107] Thus, a mounting operation for mounting the ejector-type
refrigerant cycle device on an attachment object such as a vehicle,
can be performed very efficiently. In this way, because the
integrated unit 20 is used, the length of each connection passage
can be reduced in the integrated unit 20 of the refrigerant cycle
device, thereby reducing the cost and space for mounting.
[0108] The term "integrated" as used herein may include an
integrated structure in which a part of a casing of the ejector 14
or the throttle unit 17 is shared with members, including the tank
portions 15b, 15c, 18b, 18c of the first and second evaporators 15
and 18. Alternatively, it may include integration of a relationship
of connection, for example, strong connection using welding or the
like, or weak connection using a clamp or a screw. The refrigerant
flow path constructed by such integration can be embodied in
various embodiments to be described in the following modified
examples, and cannot be limited to this embodiment and the modified
examples as described later.
(Modifications)
[0109] In the following first to fourth modified examples, as shown
in FIG. 9, the ejector 14, the first and second evaporators 15 and
18, and the temperature sensor 40 are integrally constructed as one
integrated unit 20.
[0110] In the example of FIG. 9, the throttle unit 17 is not
integrally constructed in the integrated unit 20. However, the
throttle unit 17 may be integrally constructed in the integrated
unit 20, like the above-described embodiment.
(First Modification)
[0111] FIG. 10 shows an integrated unit 20B (20) of the first
modification.
[0112] As shown in FIG. 10, a separator 15e is disposed in the
upper tank portion 15b of the first evaporator 15 to partition the
inner space of the upper tank portion 15b into a left inner space
C' and a right inner space D' such that the left space C' occupies
about one third of the inside of the upper tank portion 15b and the
right space D' occupies about two thirds thereof. A separator 15f
is disposed in the lower tank portion 15c of the first evaporator
15 to partition the inner space of the lower tank portion 15c into
a left inner space E' and a right inner space F' such that the left
space E' occupies about two thirds of the inside of the lower tank
portion 15c and the right space F' occupies about one third
thereof.
[0113] Separators 18e and 18f are disposed in the upper tank
portion 18b of the second evaporator 18 to partition the inside of
the upper tank portion 18b into about three inner spaces G', H',
and I'. A separator 18g is disposed in the lower tank portion 18c
of the second evaporator 18 to partition the inner space of the
lower tank portion 18c into a left inner space J' and a right inner
space K' such that the left space J' occupies about two thirds of
the inside of the lower tank portion 18c and the right space K'
occupies about one third thereof. In this example of FIG. 10, the
second evaporator 10 is separated into a suction-side refrigerant
evaporation portion 18a and an outflow refrigerant evaporation
portion 18a' by the separators 18e and 18f.
[0114] In this example of FIG. 10, the inner space G' of the upper
tank portion 18b of the second evaporator 18 is connected to the
downstream side of the refrigerant branch passage 16. The inner
space F' of the lower tank portion 15c of the first evaporator 15
and the inner space K' of the lower tank portion 18c of the second
evaporator 18 allow the refrigerant to pass therethrough via a
connection hole (not shown) therebetween.
[0115] The ejector 14 is disposed inside the upper tank portion 18b
of the second evaporator 18 such that the longitudinal direction of
the ejector 14 is parallel to that of the upper tank portion 18b.
The nozzle portion 14a of the ejector 14 is connected to the
downstream side of the main passage 25a as mentioned above. The
refrigerant suction port 14b is disposed in the inner space H' of
the upper tank portion 18b disposed in the second evaporator 18.
The outlet of the diffuser portion 14d is attached to be positioned
in the inner space I' of the upper tank portion 18b.
[0116] Therefore, the refrigerant suction port 14b is directly
opened in the inner space H' of the upper tank portion 18b, and the
outflow refrigerant flowing from the diffuser portion 14d flows
directly into the inner space I' of the upper tank portion 18b. As
shown in FIG. 10, the ejector 14, the first evaporator 15, the
second evaporator 18, and the respective tank portions 15b to 18c
are completely integrated as one integrate unit 20B, such that the
first evaporator 15 is disposed on the upstream side of the air
flow and the second evaporator 18 is disposed on the downstream
side of the air flow.
[0117] The ejector 14 is inserted to penetrate through holes (not
shown) provided in the separators 18e, 18f from the end in the
longitudinal direction of the upper tank portion 18b of the second
evaporator 18 and is attached and fixed by fixing means, such as
screwing, after a brazing step of integrally brazing the first
evaporator 15 and the second evaporator 18.
[0118] The ejector 14 and the separators 18e, 18f are air-tightly
fixed via O-rings (not shown) so as to prevent the refrigerant from
leaking from attachment portions between the ejector 14 and the
separators 18e, 18f (through holes). Therefore, the inner spaces G'
and H' of the upper tank portion 18b, and the inner spaces H' and
I' of the upper tank portion 18b are not in communication with each
other via the above-mentioned attachment portions (through
holes).
[0119] The refrigerant flow path of the entire integrated unit 20B
with the above-mentioned structure will be described below. First,
the refrigerant on the downstream side of the main passage 25a
flows directly into the nozzle portion 14a of the ejector 14 in the
direction of arrow "aa". Then, the refrigerant passes through the
ejector 14 (the nozzle portion 14a, the mixing portion 14c, and the
diffuser portion 14d, in this order) to be decompressed. The
low-pressure refrigerant decompressed by the ejector 14 is
collected in the inner space I' of the upper tank portion 18b of
the second evaporator 18.
[0120] The refrigerant in the inner space I' of the upper tank
portion 18b is distributed into the plurality of tubes 21 on the
right side of the second evaporator 18 in FIG. 10 to flow
downwardly as indicated by the arrow "bb", and then to be collected
in the inner space K' of the lower tank portion 18c of the second
evaporator 18. The inner space K' is in communication with the
inner space F' of the lower tank portion 15c of the first
evaporator 15, thus allowing the refrigerant to flow into the inner
space F'.
[0121] The refrigerant in the inner space F' is distributed into
the plurality of tubes 21 on the right side of the first evaporator
15 to flow upwardly as indicated by the arrow "cc", and then to
flow into the inner space D' of the upper tank portion 15b of the
first evaporator 15. The refrigerant flowing into the inner space
D' moves leftward in the inner space D'. The refrigerant moving
leftward in the inner space D' is distributed into the plurality of
tubes 21 at the center area of the first evaporator 15 to flow
downwardly as indicated by the arrow "dd", and then to flow into
the inner space E' of the lower tank portion 15c.
[0122] The refrigerant flowing into the inner space E' moves
leftward in the inner space E'. The refrigerant moving leftward in
the inner space E' is distributed into the plurality of tubes 21 on
the left side of the first evaporator 15 to flow upwardly as
indicated by the arrow "ee", and then to be collected in the inner
space C' of the upper tank portion 15b. The refrigerant collected
in the inner space C' of the upper tank portion 15b flows from the
upper tank portion 15b as indicated by the arrow "ff" to the
suction side of the compressor 11. Thus, the outflow refrigerant
having passed though the outflow refrigerant evaporation portion
18a' of the second evaporator 18 changes a flow direction twice
(more than one time) in the first evaporator 15 while passing
through the first evaporator 15 to be brought into a vapor phase
having an appropriate degree of superheat at a superheat area that
is positioned on the left upper part of the first evaporator 15 in
FIG. 10.
[0123] The low-pressure refrigerant on the downstream side of the
refrigerant branch passage 16 and decompressed by the throttle unit
17 flows into the inner space G' of the upper tank portion 18b of
the second evaporator 18. The refrigerant in the inner space G' of
the upper tank portion 18b is distributed into the plurality of
tubes 21 on the left side of the second evaporator 18 to flow
downwardly in the direction of arrow "gg", and then to flow into
the inner space J' of the lower tank portion 18c of the second
evaporator 18.
[0124] The refrigerant flowing into the inner space J' moves
rightward in the inner space J' of the lower tank portion 18c. The
refrigerant moving rightward in the inner space J' is distributed
into the plurality of tubes 21 at the center area of the second
evaporator 18 to flow upwardly as indicated by the arrow "hh", and
then to be collected in the inner space H' of the upper tank
portion 18b. The refrigerant collected in the inner space H' of the
upper tank portion 18b is drawn into the ejector 14 from the
refrigerant suction port 14b of the ejector 14.
[0125] Thus, the refrigerant passing through the suction-side
refrigerant evaporation portion 18a of the second evaporator 18
changes a flow direction once in the second evaporator 18 to be
brought into a vapor phase having an appropriate degree of
superheat at a superheat area positioned on the left upper part of
the first evaporator 15. The refrigerant flowing into the
suction-side refrigerant evaporation portion 18a exchanges heat
only at the area indicated by the arrows gg to hh of FIG. 10, among
the second evaporator 18.
[0126] The ratio of use of the second evaporator 18 on the
downstream air side, which occupies the suction-side refrigerant
evaporation portion 18a, is about two thirds (about 70%) of the
second evaporator 18 by arrangement and positioning of the
separators 18f and 18g. In this way, the arrangement ratio between
the suction-side refrigerant evaporation portion 18a and the
outflow refrigerant evaporation portion 18a' in the second
evaporator 18 on downwind side can be adjusted easily by
arrangement and positioning of the separators 18f and 18g. The
temperature sensor 40 is disposed at the part MC (on the lower side
of the flow part indicated by the arrow "hh" in this modified
example) in which the refrigerant flows upwardly from the lower
tank portion 18c of the second evaporator 18, at a position close
to the lower tank portion 18c, like the above-mentioned embodiment.
Furthermore, similarly to the above-described embodiment, the frost
prevention control of the second evaporator 18 is performed by the
controller 50 based on the signal detected by the temperature
sensor 40 (40A, 40B).
(Second Modification)
[0127] In the above-mentioned first modified example, the
ejector-type refrigerant cycle device 10 using the integrated unit
20B has been explained. However, in the second modified example, an
integrated unit 20C (20) shown in FIG. 11 is used for the
ejector-type refrigerant cycle device 10. FIG. 11 is a perspective
view showing an outline of the entire structure of the integrated
unit 20C, in which the basic structures of the first evaporator 15
and the second evaporator 18 are similar to those of the first
modified example.
[0128] The integrated unit 20C of FIG. 11 differs from the
integrated unit 20B of the first modified example in arrangement
and positioning of the separators disposed in the tank portions 15b
to 18c, as well as in arrangement and positioning of the ejector
14, and thus in the refrigerant flow path. Ah shown in FIG. 11, a
separator 15e' is disposed in the upper tank portion 15b of the
first evaporator 15 to partition the inner space of the upper tank
portion 15b into a left inner space L' and a right inner space M'
such that the left space L' occupies about one half of the inside
of the upper tank portion 15b and the right space M' occupies about
one half thereof. No separator is disposed in the lower tank
portion 15c of the first evaporator 15, in which one inner space N'
is formed.
[0129] A separator 18e' is disposed in the upper tank portion 18b
of the second evaporator 18 to partition the inner space of the
upper tank portion 18b into a left inner space O' and a right inner
space P' such that the left space O' occupies about one half of the
inside of the upper tank portion 18b and the right space P'
occupies about one half thereof. No separator is disposed in the
lower tank portion 18c of the second evaporator 18 to construct one
inner space Q'. In this modified example, the inner space O' of the
upper tank portion 18b of the second evaporator 18 is connected to
the downstream side of the refrigerant branch passage 16.
[0130] In addition, the ejector 14 is disposed inside the upper
tank portion 18b of the second evaporator 18, the nozzle portion
14a of the ejector 14 is connected to the downstream side of the
main passage 25a, and the refrigerant suction port 14b is attached
to be positioned in the inner space P' of the upper tank portion
18b. Therefore, the refrigerant suction port 14b is directly opened
in the inner space P' of the upper tank portion 18b.
[0131] Furthermore, the outflow refrigerant flowing from the
diffuser portion 14d of the ejector 14 is allowed to flow into the
inner space M' of the upper tank portion 15b of the first
evaporator 15 via piping (not shown) disposed outside the upper
tank portion 18b. It is apparent that a passage for guiding the
outflow refrigerant into the inner space M' may be constructed in
the upper tank portion 18b. Also in the integrated unit 20C, the
ejector 14 is assembled to the inside of the upper tank portion 18b
of the second evaporator 18, like the first modified example, after
integrally connecting the first and second evaporators 15, 18 and
the tank portions 15b, 18c by brazing.
[0132] The refrigerant flow path of the entire integrated unit 20C
with the above-mentioned structure will be described below. First,
the refrigerant on the downstream side of the main passage 25a
flows directly into the nozzle portion 14a of the ejector 14 as
indicated by the arrow "aa" in FIG. 11. Then, the refrigerant
passes through the ejector 14 to be decompressed. The low-pressure
refrigerant decompressed by the ejector 14 flows into the inner
space M' of the upper tank portion 15b of the first evaporator 15
via external piping of the upper tank portion 18b.
[0133] The refrigerant flowing into the inner space M' is
distributed into the plurality of tubes 21 on the right side of the
first evaporator 15 to flow downwardly as indicated by the arrow
"ii", and then to flow into the inner space N' of the lower tank
portion 15c of the first evaporator 15. The refrigerant flowing
into the inner space N' moves leftward in the inner space N' of the
lower tank portion 15c. The refrigerant moving leftward in the
inner space N' is distributed into the plurality of tubes 21 on the
left side of the first evaporator 15 to flow upwardly as indicated
by the arrow "jj", and then to be collected in the inner space L'
of the upper tank portion 15b.
[0134] The refrigerant collected in the inner space L' of the upper
tank portion 15b flows from the upper tank portion 15b to the
suction side of the compressor 11 as indicated by the arrow "ff".
Thus, the outflow refrigerant flowing out of the diffuser portion
14d to pass through the first evaporator 15 changes a flow
direction once in the first evaporator 15 to be brought into a
vapor phase having an appropriate degree of superheat at a
superheat area positioned on the left upper part of the first
evaporator 15.
[0135] The low-pressure refrigerant on the downstream side of the
refrigerant branch passage 16 and decompressed by the throttle unit
17 flows into the inner space O' of the upper tank portion 18b of
the second evaporator 18. The refrigerant flowing into the inner
space O' is distributed into the plurality of tubes 21 on the left
side of the second evaporator 18 to flow downwardly as indicated by
the arrow "kk", and then to flow into the inner space Q' of the
lower tank portion 18c of the second evaporator 18. The refrigerant
flowing into the inner space Q' moves rightward in the inner space
Q' in FIG. 11.
[0136] The refrigerant moving rightward in the inner space Q' of
the lower tank portion 18c of the second evaporator 18 is
distributed into the plurality of tubes 21 on the right side of the
second evaporator 18 to flow upwardly as indicated by the arrow
"ll", and then to be collected in the inner space P' of the upper
tank portion 18b. The refrigerant collected in the inner space P'
is drawn from the refrigerant suction port 14c of the ejector 14
into the ejector 14. Thus, the suction-port side refrigerant
passing through the second evaporator 18 changes a flow direction
once in the second evaporator 18 to be brought into a vapor phase
having an appropriate degree of superheat at a superheat area
positioned on the right upper part of the second evaporator 18.
[0137] Because the refrigerant passes through the integrated unit
20C as mentioned above, the second evaporator 18 constructs only
the suction-side refrigerant evaporating portion 18a, and not the
outflow refrigerant evaporating portion 18a' of first modified
example of FIG. 10. Other components have the same structures as
those in the first modified example. The temperature sensor 40 (not
shown) is disposed at the part MC in which the refrigerant flow
flows upwardly from the lower tank portion 18c of the second
evaporator 18 (on the lower side of the flow part as indicated by
the arrow ll in this modified example), like the above-mentioned
embodiments and modified examples. Furthermore, the part MC is
located at a position close to the lower tank portion 18c. In
addition, similarly to the above-described embodiment, the frost
prevention control of the second evaporator 18 is performed by the
controller 50 based on the signal detected by the temperature
sensor 40 (40A, 40B).
(Third Modification)
[0138] In the above-mentioned examples, the ejector-type
refrigerant cycle device 10 employing the integrated unit 20A, 20B,
20C has been explained. However, in the third modified example, an
integrated unit 20D (20) shown in FIG. 12 is used for the
ejector-type refrigerant cycle device 10. FIG. 12 is a perspective
view showing an outline of the entire structure of the integrated
unit 20D. Also in the integrated unit 20D, the ejector 14, the
first and second evaporators 15 and 18, and the temperature sensor
40 are integrally constructed, like the integrated unit 20B,
20C.
[0139] The basic structures of the first and second evaporators 15
and 18 of the integrated unit 20D are the same as those of the
first or second modified example. The integrated unit 20D differs
from the integrated unit 20B, 20C in arrangement and positioning of
the separators disposed in the tank portions 15b to 18c and in
arrangement and positioning of the ejector 14. Thus, the third
modified example differs from the first or second modified example
in refrigerant flow path.
[0140] As shown in FIG. 12, no separator is disposed in the upper
tank portion 15b of the first evaporator 15, so that one inner
space R' is formed in the upper tank portion 15b. A separator 15f
is disposed in the lower tank portion 15c of the first evaporator
15 to partition the inner space of the lower tank portion 15c into
a left inner space S' and a right inner space T' such that the left
space S' occupies about one half of the inside of the lower tank
portion 15c and the right space T' occupies about one half
thereof.
[0141] A separator 18e' is disposed in the upper tank portion 18b
of the second evaporator 18 to partition the inner space of the
upper tank portion 18b into a left inner space O' and a right inner
space P' such that the left space O' occupies about one half of the
inside of the upper tank portion 18b and the right space P'
occupies about one half thereof. A separator 18f' is disposed in
the lower tank portion 18c of the second evaporator 18 to partition
the inner space of the lower tank portion 18c into a left inner
space U' and a right inner space V' such that the left space U'
occupies about one half of the inside of the lower tank portion 18c
and the right space V' occupies about one half thereof.
[0142] In this modified example, the inner space U' of the lower
tank portion 18c of the second evaporator 18 is connected to the
downstream side of the refrigerant branch passage 16. The
refrigerant can be circulated through the inner space T' of the
lower tank portion 15c of the first evaporator 15 and the inner
space V' of the lower tank portion 18c on the lower side of the
second evaporator 18 via a communication hole (not shown)
therebetween.
[0143] The ejector 14 is disposed in the upper tank portion 18b of
the second evaporator 18. The nozzle portion 14a of the ejector 14
is connected to the downstream side of the main passage 25a. The
refrigerant suction port 14b is positioned in the inner space O' of
the upper tank portion 18b. The outlet of the diffuser portion 14d
is attached to be disposed in the inner space P' of the upper tank
portion 18b.
[0144] Thus, the refrigerant suction port 14b is directly opened in
the inner space O' of the upper tank portion 18b, and the outlet of
the diffuser portion 14d is directly opened in the inner space P'
of the upper tank portion 18b. Also in the integrated unit 20D, the
ejector 14 is assembled to the inside of the upper tank portion 18b
of the second evaporator 18 after integrally connecting the first
and second evaporators 15 and 18 and the tank portions 15b and 18c
by brazing, like the above-mentioned embodiment.
[0145] Now, the refrigerant flow path of the entire integrated unit
20D with the above-mentioned structure will be described below.
First, the refrigerant on the downstream side of the main passage
25a flows directly into the nozzle portion 14a of the ejector 14 as
indicated by the arrow "aa" in FIG. 12. Then, the refrigerant
passes through the ejector 14 to be decompressed. The low-pressure
refrigerant decompressed by the ejector 14 flows into the inner
space P' of the upper tank portion 15b of the first evaporator
15.
[0146] The refrigerant flowing into the inner space P' of the upper
tank portion 18b is distributed into the plurality of tubes 21 on
the right side of the second evaporator 18 to flow downwardly as
indicated by the arrow "mm", and then to be collected in the inner
space V' of the lower tank portion 18c of the second evaporator 18.
Since the inner space V' of the lower tank portion 18c communicates
with the inner space T' of the lower tank portion 15c of the first
evaporator 15, the refrigerant flows into the inner space T' of the
lower tank portion 15c from the inner space V' of the lower tank
portion 18c.
[0147] The refrigerant flowing into the inner space T' is
distributed into the plurality of tubes 21 on the right side of the
first evaporator 15 to flow upwardly as indicated by the arrow
"nn", and then to flow into the inner space R' of the upper tank
portion 15b. The refrigerant flowing into the inner space R' moves
leftward in the inner space R' of the upper tank portion 15b. The
refrigerant moving leftward in the inner space R' is distributed
into the plurality of tubes 21 on the left side of the first
evaporator 15 to flow downwardly as indicated by the arrow "oo",
and then to flow into the inner space S' of the lower tank portion
15c of the first evaporator 15.
[0148] The refrigerant flowing into the inner space S' flows from
the lower tank portion 15c to the suction side of the compressor 11
as indicated by the arrow "pp". Thus, the outflow refrigerant
flowing from the diffuser portion 14d to pass through the first
evaporator 15 changes a flow direction once in the first evaporator
15 and in the second evaporator 18 to be brought into a vapor phase
having an appropriate degree of superheat at a superheat area
positioned on the left lower part of the first evaporator 15.
[0149] The low-pressure refrigerant on the downstream side of the
refrigerant branch passage 16 and decompressed by the throttle unit
17 flows into the inner space U' of the lower tank portion 18c of
the second evaporator 18. The refrigerant flowing into the inner
space U' is distributed into the plurality of tubes 21 on the left
side of the second evaporator 18 to flow upwardly as indicated by
the arrow "qq", and then to be collected into the inner space O' of
the upper tank portion 18b. The refrigerant collected in the inner
space O' of the upper tank portion 18b is drawn from the
refrigerant suction port 14c of the ejector 14 to the inside of the
ejector 14.
[0150] Thus, the refrigerant is brought into the vapor phase having
the appropriate superheat degree at the superheat area on the upper
left portion of the second evaporator 18. The suction-port side
refrigerant to be drawn into the refrigerant suction port 14c of
the ejector 14 exchanges heat in the second evaporator 18 only at
the area indicated by the arrow "qq" of FIG. 12. Thus, in this
modified example, the ratio of the suction-side refrigerant
evaporation portion 18a is about one half (about 50%) of the second
evaporator 18, and the ratio of the outflow refrigerant evaporation
portion 18a' is about one half (about 50%) of the second evaporator
18, by arrangement and positioning of the separators 18e' and
18f.
[0151] The throttle unit 17 of this modified example is controlled
such that a flow ratio Ge/G of a flow amount Ge of the suction-port
side refrigerant to a flow amount G of the refrigerant discharged
from the compressor 11 is about 0.5. Other components are the same
as those of the first modified example. The temperature sensor 40
(not shown) is positioned at the part MC in which the refrigerant
flows upwardly from the lower tank portion 18c of the second
evaporator 18 (on the lower side of the flow part indicated by the
arrow "qq" in this modified example), at a position close to the
lower tank portion 18c, like the above-mentioned embodiment and
modified examples.
(Fourth Modification)
[0152] In the above-mentioned first modified example, the
ejector-type refrigerant cycle device 10 employing the integrated
unit 20B has been explained. However, in the fourth modified
example, an integrated unit 20E (20) shown in FIG. 13 is used for
the ejector-type refrigerant cycle device 10. FIG. 13 is a
perspective view showing an outline of the entire structure of the
integrated unit 20E. Also in the integrated unit 20E, the ejector
14, the first and second evaporators 15 and 18, and the temperature
sensor 40 are integrally constructed, like the integrated unit
20B.
[0153] The basic structures of the first and second evaporators 15
and 18 of the integrated unit 20E are the same as those of the
integrated unit 20B of the first modified example. The integrated
unit 20E differs from the integrated unit 20B in arrangement and
positioning of the separators disposed in the tank portions 15b to
18c and in arrangement and positioning of the ejector 14. Thus,
this modified example differs from the first modified example in
refrigerant flow path.
[0154] A separator 15e'' is disposed in the upper tank portion 15b
of the first evaporator 15 to partition the inner space of the
upper tank portion 15b into a left inner space W' and a right inner
space X' such that the left space W' occupies about two thirds of
the inside of the upper tank portion 15b and the right space X'
occupies about one third thereof. A separator 15f'' is disposed in
the lower tank portion 15c of the first evaporator 15 to partition
the inner space of the lower tank portion 15c into a left inner
space Y' and a right inner space Z' such that the left space Y'
occupies about one third of the inside of the lower tank portion
15c and the right space Z' occupies about two thirds thereof.
[0155] A separator 18e' is disposed in the upper tank portion 18b
of the second evaporator 18 to partition the inner space of the
upper tank portion 18b into a left inner space O' and a right inner
space P' such that the left space O' occupies about one half of the
inside of the upper tank portion 18b and the right space P'
occupies about one half thereof. No separator is disposed in the
lower tank portion 18c of the second evaporator 18, in which one
inner space Q' is formed. Note that in this modified example, the
inner space P' of the upper tank portion 18b of the second
evaporator 18 is connected to the downstream side of the
refrigerant branch passage 16.
[0156] The ejector 14 is disposed inside the upper tank portion 18b
of the second evaporator 18, like the first modified example. The
nozzle portion 14a of the ejector 14 is connected to the downstream
side of the main passage 25a, and the refrigerant suction port 14b
is disposed in the inner space O' of the upper tank portion 18b.
The outlet of the diffuser portion 14d is attached to be positioned
in an upper space part of the inner space P' of the upper tank
portion 18b. Thus, the refrigerant suction port 14b is directly
opened in the inner space O' of the upper tank portion 18b, and
further the outlet of the diffuser portion 14d is directly opened
in the inner space P' of the upper tank portion 18b.
[0157] As mentioned above, the refrigerant on the downstream side
of the refrigerant branch passage 16 and the refrigerant flowing
from the diffuser portion 14d flow into the inner space P'. Thus,
in this embodiment, the inner space P' is divided into two
independent spaces, that is, a space into which the refrigerant on
the downstream side of the refrigerant branch passage 16 flows and
a space into which the refrigerant flowing from the diffuser
portion 14d flows.
[0158] Specifically, a partition plate not shown is provided for
vertically dividing the inner space P' into the two spaces. In this
case, the refrigerant flowing from the diffuser portion 14d flows
into the upper space, and the refrigerant on the downstream side of
the refrigerant branch passage 16 flows into the lower space.
Furthermore, the refrigerant can flow through this upper space and
the inner space X' of the upper tank portion 15b of the first
evaporator 15 via a communication hole not shown.
[0159] A passage or the like may be provided inside the upper tank
portion 18b to allow the refrigerant flowing from the diffuser
portion 14d to flow directly into the inner space X' and not into
the inner space P' without dividing the inner space P' into the two
independent spaces. Also in the integrated unit 20E, the ejector 14
is assembled to the inside of the upper tank portion 18b of the
second evaporator 18 after integrally connecting the first and
second evaporators 15, 18 and the tank portions 15b to 18c by
brazing, like the first modified example.
[0160] Now, the refrigerant flow path of the entire integrated unit
20E with the above-mentioned structure will be described below.
First, the refrigerant on the downstream side of the main passage
25a flows directly into the nozzle portion 14a of the ejector 14 as
indicated by the arrow "aa". Then, the refrigerant passes through
the ejector 14 to be decompressed. The low-pressure refrigerant
decompressed flows into the inner space X' of the upper tank
portion 15b of the first evaporator 15 via the upper space of the
inner space P' of the upper tank portion 18b of the second
evaporator 18.
[0161] The refrigerant flowing into the inner space X' is
distributed into the plurality of tubes 21 on the right side of the
first evaporator 15 to flow downwardly as indicated by the arrow
"rr", and then to flow into the inner space Z' of the lower tank
portion 15c of the first evaporator 15. The refrigerant flowing
into the inner space Z' moves leftward in the inner space Z'. The
refrigerant moving leftward in the inner space Z' is distributed
into the plurality of tubes 21 at the center area of the first
evaporator 15 to flow upwardly as indicated by the arrow "ss", and
then to flow into the inner space W' of the upper tank portion 15b
of the first evaporator 15.
[0162] The refrigerant flowing into the inner space W' of the upper
tank portion 15b moves leftward inside the inner space W'. The
refrigerant moving leftward inside the inner space W' is
distributed into the plurality of tubes 21 on the left side of the
first evaporator 15 to flow downwardly as indicated by the arrow
tt, and then to be collected in the inner space Y' of the lower
tank portion 15c of the first evaporator 15. The refrigerant
collected in the inner space Y' flows from the lower tank portion
15c to the suction side of the compressor 11 as indicated by the
arrow "pp".
[0163] Thus, the outflow refrigerant flowing out of the diffuser
portion 14d to pass thorough the first evaporator 15 changes a flow
direction twice (more than one time) in the first evaporator 15 to
be brought into a vapor phase having an appropriate degree of
superheat at a superheat area positioned on the left lower part of
the first evaporator 15. In contrast, the low-pressure refrigerant
on the downstream side of the refrigerant branch passage 16
depressed by the throttle unit 17 flows into a lower space part of
the inner space P' of the upper tank portion 18b of the second
evaporator 18.
[0164] The refrigerant flowing into the lower space part of the
inner space P' is distributed into the plurality of tubes 21 on the
right side of the second evaporator 18 to flow downwardly as
indicated by the arrow "uu", and then to flow into the inner space
Q' of the lower tank portion 18c. The refrigerant flowing into the
inner space Q' moves leftward inside the inner space Q'. The
refrigerant moving leftward in the inner space Q' is distributed
into the plurality of tubes 21 on the left side of the second
evaporator 18 to flow upwardly as indicated by the arrow "vv" and
then to be collected into the inner space O'. The refrigerant
collected in the inner space O' is drawn into the ejector 14 from
the refrigerant suction port 14c of the ejector 14.
[0165] Thus, the refrigerant is brought into a vapor phase having
an appropriate degree of superheat at a superheat area positioned
on the left upper part of the second evaporator 18. The refrigerant
passes through the integrated unit 20E as mentioned above, and thus
the second evaporator 18 constructs only the suction-side
refrigerant evaporation portion 18a and not the outflow refrigerant
evaporating portion 18a'. Other components have the same structures
as those in the first modified example. The temperature sensor 40
not shown is disposed at the part MC where the refrigerant flows
upwardly from the lower tank portion 18c of the second evaporator
18 (on the lower side of the flow part as indicated by the arrow
"vv" in this modified example), at a position close to the lower
tank portion 18c, like the above-mentioned embodiment and modified
examples.
(Other Modifications)
[0166] Although the present invention has been fully described in
connection with the embodiment and the modified examples thereof
with reference to the accompanying drawings, it is to be noted that
various changes and modifications will become apparent to those
skilled in the art.
[0167] (1) In the above-mentioned embodiment, other components
except for the ejector 14, that is, the first and second
evaporators 15 and 18, the first and second connection blocks 23
and 24, and the throttle unit 17 are integrally brazed when these
components of the integrated unit 20A are integrally assembled.
However, these components can be integrally assembled by various
fixing means other than brazing, including screwing, caulking,
welding, adhesion and the like.
[0168] In the above-described embodiment, exemplary fixing means of
the ejector 14 is the screwing, but any other fixing means that may
not be thermally deformed can be used instead of the screwing.
Specifically, fixing means, such as caulking or adhesion, may be
used to fix the ejector 14.
[0169] (2) Although the above-mentioned embodiment has described a
vapor-compression subcritical cycle using refrigerant whose high
pressure does not exceed the critical pressure, such as a
Freon-based or HC-based refrigerant, the present invention may be
applied to a vapor-compression supercritical cycle using
refrigerant whose high pressure exceeds the critical pressure, such
as carbon dioxide (CO.sub.2). In this case, the compressor
discharge refrigerant only radiates heat in the supercritical state
using the radiator 12 in the supercritical cycle, the refrigerant
is not condensed, and thus the liquid receiver 12a disposed on the
high-pressure side cannot exhibit a vapor-liquid separation effect
of the refrigerant and a storage effect of the excessive liquid
refrigerant. The supercritical cycle may employ an accumulator (not
shown) constructing a low-pressure side vapor-liquid separator
disposed on the refrigerant outlet side of the first evaporator
15.
[0170] (3) In the above-mentioned embodiment, the throttle unit 17
may be constructed of a fixed throttle, such as a capillary tube or
an orifice. However, the throttle unit 17 may be constructed of an
electric control valve whose valve opening degree (opening degree
of throttle passage) is adjustable by an electric actuator.
Alternatively, the throttle unit 17 may be constructed of a
combination of a fixed throttle, such as a capillary tube or a
fixed throttle hole, and an electromagnetic valve.
[0171] (4) In the above-mentioned embodiment, the ejector 14 is a
fixed ejector with a fixed nozzle portion 14a whose passage area is
constant. However, the ejector 14 may be a variable ejector having
a variable nozzle portion whose passage area is adjustable.
Specifically, the variable nozzle portion may be constructed of a
mechanism which is adapted to adjust a nozzle passage area by
controlling the position of a needle inserted into a passage of the
variable nozzle portion by an electric actuator.
[0172] (5) In the above-mentioned embodiment, a vehicle compartment
space or a freezer and refrigerator space of a freezer car serves
as a space to be cooled by the first and second evaporator 15 and
18. However, the present invention is not limited to such a vehicle
space, and can be used for various refrigerant cycle devices,
including stationary one.
[0173] (6) In the above-mentioned embodiment, the thermal expansion
valve 13 and the temperature sensing portion 13a are independently
provided from the integrated unit 20 of the ejector-type
refrigerant cycle device, as shown in FIG. 1. However, the thermal
expansion valve 13 and the temperature sensing portion 13a may be
integrally assembled to the integrated unit 20 of the ejector-type
refrigerant cycle device. For example, the thermal expansion valve
13 and the temperature sensing portion 13a can be accommodated in
the first connection block 23 of the integrated unit 20. In this
case, the refrigerant inlet 25 is located between the liquid
receiver 12a and the thermal expansion valve 13, and the
refrigerant outlet 26 is located between a passage part with the
temperature sensing portion 13a set therein and the compressor
11.
[0174] (7) Furthermore, the temperature sensor 40 can be located to
detect any one of its fin temperature and its tube temperature so
as to detect the frost of the second evaporator 18, and can be
located to detect an air temperature immediately after passing
through the second evaporator 18 so as to detect the frost of the
second evaporator 18. Even in this case, the controller 50 can
perform the frost prevention control in accordance with the
temperature detected by the temperature sensor 40.
[0175] Such changes and modifications are to be understood as being
within the scope of the present invention as defined by the
appended claims.
* * * * *