U.S. patent application number 13/600487 was filed with the patent office on 2013-03-07 for refrigerant cycle device.
This patent application is currently assigned to DENSO CORPORATION. The applicant listed for this patent is Atsushi Inaba. Invention is credited to Atsushi Inaba.
Application Number | 20130055751 13/600487 |
Document ID | / |
Family ID | 47710948 |
Filed Date | 2013-03-07 |
United States Patent
Application |
20130055751 |
Kind Code |
A1 |
Inaba; Atsushi |
March 7, 2013 |
REFRIGERANT CYCLE DEVICE
Abstract
A refrigerant cycle device includes a compressor, a using-side
heat exchanger which heats a heat-exchange fluid by performing heat
exchange between the heat-exchange fluid and high-pressure
refrigerant flowing out of the compressor, an intermediate pressure
passage through which intermediate-pressure gas refrigerant
obtained by decompression of the high-pressure refrigerant flowing
out of the using-side heat exchanger is introduced into a
intermediate pressure port of the compressor, an exterior heat
exchanger which evaporates low-pressure refrigerant obtained by
decompression of the high-pressure refrigerant flowing out of the
using-side heat exchanger and causes the evaporated refrigerant to
flow toward a suction port of the compressor, and an auxiliary
heater which heats the heat-exchange fluid before or at the same
time as that the using-side heat exchanger heats the heat-exchange
fluid.
Inventors: |
Inaba; Atsushi;
(Okazaki-city, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Inaba; Atsushi |
Okazaki-city |
|
JP |
|
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
47710948 |
Appl. No.: |
13/600487 |
Filed: |
August 31, 2012 |
Current U.S.
Class: |
62/498 |
Current CPC
Class: |
F25B 2400/23 20130101;
B60H 2001/225 20130101; F25B 2341/0662 20130101; Y02B 30/70
20130101; B60H 2001/00128 20130101; F25B 2400/13 20130101; F25B
5/04 20130101; F25B 6/04 20130101; Y02B 30/72 20130101; B60H 1/2218
20130101; F25B 1/10 20130101; F25B 2400/0409 20130101; F25B
2700/2104 20130101; F25B 2400/121 20130101; F25B 2600/2501
20130101; F25B 2341/0653 20130101; B60H 2001/2237 20130101; F25B
2700/2106 20130101 |
Class at
Publication: |
62/498 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 5, 2011 |
JP |
2011-192559 |
Jul 31, 2012 |
JP |
2012-169404 |
Claims
1. A refrigerant cycle device comprising: a compressor having a
suction port through which low-pressure refrigerant is drawn, a
discharge port through which high-pressure refrigerant compressed
in a compression portion is discharged, and an intermediate
pressure port through which intermediate-pressure gas refrigerant
is drawn to be combined with refrigerant being compressed in the
compression portion; a using-side heat exchanger which heats a
heat-exchange fluid by performing heat exchange between the
heat-exchange fluid and the high-pressure refrigerant discharged
from the compressor; an intermediate pressure passage through which
intermediate-pressure gas refrigerant obtained by decompression of
the high-pressure refrigerant flowing out of the using-side heat
exchanger is introduced into the intermediate pressure port; an
exterior heat exchanger in which low-pressure refrigerant obtained
by decompression of the high-pressure refrigerant flowing out of
the using-side heat exchanger evaporates, the exterior heat
exchanger causing the evaporated low-pressure refrigerant to flow
to the suction port; and an auxiliary heater which heats the
heat-exchange fluid before or at the same time as that the
using-side heat exchanger heats the heat-exchange fluid.
2. A refrigerant cycle device comprising: a compressor having a
suction port through which low-pressure refrigerant is drawn, a
discharge port through which high-pressure refrigerant compressed
in a compression portion is discharged, and an intermediate
pressure port through which intermediate-pressure gas refrigerant
is drawn to be combined with refrigerant being compressed in the
compression portion; a using-side heat exchanger which heats a
heat-exchange fluid by performing heat exchange between the
heat-exchange fluid and the high-pressure refrigerant discharged
from the compressor; a higher-pressure side expansion device
configured to decompress the high-pressure refrigerant flowing out
of the using-side heat exchanger into intermediate-pressure
refrigerant; a gas-liquid separation portion configured to separate
the intermediate-pressure refrigerant flowing out of the
higher-pressure side expansion device into intermediate-pressure
gas refrigerant and intermediate-pressure liquid refrigerant, the
gas-liquid separation portion causing the separated
intermediate-pressure gas refrigerant to flow to the intermediate
pressure port; a lower-pressure side expansion device configured to
decompress the separated intermediate-pressure liquid refrigerant
flowing out of the gas-liquid separation portion into low-pressure
refrigerant; an exterior heat exchanger in which the low-pressure
refrigerant flowing out of the lower-pressure side expansion device
evaporates, the exterior heat exchanger causing the evaporated
low-pressure refrigerant to flow to the suction port; and an
auxiliary heater which heats the heat-exchange fluid before or at
the same time as that the using-side heat exchanger heats the
heat-exchange fluid.
3. A refrigerant cycle device comprising: a compressor having a
suction port through which low-pressure refrigerant is drawn, a
discharge port through which high-pressure refrigerant compressed
in a compression portion is discharged, and an intermediate
pressure port through which intermediate-pressure gas refrigerant
is drawn to be combined with refrigerant being compressed in the
compression portion; a using-side heat exchanger which heats a
heat-exchange fluid by performing heat exchange between the
heat-exchange fluid and the high-pressure refrigerant discharged
from the compressor; a refrigerant branch portion at which a
refrigerant passage of the high-pressure refrigerant flowing out of
the using-side heat exchanger branches into a first refrigerant
passage and a second refrigerant passage, a first expansion device
provided in the first refrigerant passage to decompress the
high-pressure refrigerant flowing out of the using-side heat
exchanger into intermediate-pressure refrigerant; an inner heat
exchanger in which the high-pressure refrigerant flowing from the
using-side heat exchanger through the second refrigerant passage
exchanges heat with the intermediate-pressure refrigerant
decompressed by the first expansion device, the inner heat
exchanger causing the heat-exchanged intermediate-pressure
refrigerant to flow to the intermediate pressure port; a second
expansion device configured to decompress the heat-exchanged
high-pressure refrigerant flowing out of the inner heat exchanger
into low-pressure refrigerant; an exterior heat exchanger in which
the low-pressure refrigerant flowing out of the second expansion
device evaporates, the exterior heat exchanger causing the
evaporated low-pressure refrigerant to flow to the suction port; an
auxiliary heater which heats the heat-exchange fluid before or at
the same time as that the using-side heat exchanger heats the
heat-exchange fluid.
4. The refrigerant cycle device according to claim 1, wherein the
auxiliary heater is arranged upstream of the using-side heat
exchanger in a flow direction of the heat-exchange fluid to heat
the heat-exchange fluid before the heat-exchange fluid being heated
by the using-side heat exchanger.
5. The refrigerant cycle device according to claim 1, wherein the
auxiliary heater and the using-side heat exchanger are arranged in
a direction perpendicular to a flow direction of the heat-exchange
fluid, and are integrated with each other to heat the heat-exchange
fluid at the same time.
6. The refrigerant cycle device according to claim 1, wherein the
auxiliary heater has a heating capacity lower than a standard
heating capacity, which is defined as a necessary heating capacity
of the auxiliary heater for heating the heat-exchange fluid to a
target temperature in a case where (i) the auxiliary heater is
arranged to heat the heat-exchange fluid which has been heated in
the using-side heat exchanger, and (ii) the heating capacity of the
auxiliary heater and a heating capacity of the using-side heat
exchanger are used for heating the heat-exchange fluid.
7. The refrigerant cycle device according to claim 1, further
comprising a heating capacity adjusting portion configured to
adjust a capacity of the auxiliary heater for heating the
heat-exchange fluid so that a pressure of refrigerant in the
using-side heat exchanger becomes a target pressure.
8. The refrigerant cycle device according to claim 1, wherein the
auxiliary heater is an electric heater which generates heat by
receiving supply of electric power.
9. The refrigerant cycle device according to claim 1, wherein the
auxiliary heater is an auxiliary heat exchanger configured to heat
the heat-exchange fluid by utilizing heat of heat medium that cools
an external heat source.
10. The refrigerant cycle device according to claim 7, wherein the
auxiliary heater is an electric heater which generates heat by
receiving supply of electric power, and the heating capacity
adjusting portion adjusts the heating capacity of the electric
heater by adjusting a supply of the electric power to the electric
heater.
11. The refrigerant cycle device according to claim 7, wherein the
auxiliary heater is an auxiliary heat exchanger configured to heat
the heat-exchange fluid by using heat medium, which cools an
external heat source, as a heat source, and the heating capacity
adjusting portion adjusts the heating capacity of the auxiliary
heat exchanger by adjusting a flow amount of the heat medium
flowing into the auxiliary heat exchanger.
12. The refrigerant cycle device according to claim 7, wherein the
auxiliary heater is a plurality of electric heaters configured to
generate heat by energization thereof, and the heating capacity
adjusting portion adjusts the heating capacity of the plurality of
electric heaters by changing number of electric heaters
energized.
13. The refrigerant cycle device according to claim 7 wherein the
heating capacity adjusting portion activates the auxiliary heater
when the capacity of the using-side heat exchanger for heating the
heat-exchange fluid is incapable of being increased by a heating
capacity control of the using-side heat exchanger.
14. The refrigerant cycle device according to claim 7, wherein the
heating capacity adjusting portion decreases the capacity of the
auxiliary heater for heating the heat-exchange fluid when the
pressure of refrigerant in the using-side heat exchanger is higher
than the target pressure, and the heating capacity adjusting
portion increases the capacity of the auxiliary heater for heating
the heat-exchange fluid when the pressure of refrigerant in the
using-side heat exchanger is equal to or lower than the target
pressure.
15. The refrigerant cycle device according to claim 2, wherein the
auxiliary heater is arranged upstream of the using-side heat
exchanger in a flow direction of the heat-exchange fluid to heat
the heat-exchange fluid before the using-side heat exchanger heats
the heat-exchange fluid.
16. The refrigerant cycle device according to claim 2, wherein the
auxiliary heater and the using-side heat exchanger are arranged in
a direction perpendicular to a flow direction of the heat-exchange
fluid, and are integrated with each other to heat the heat-exchange
fluid at the same time.
17. The refrigerant cycle device according to claim 2, wherein the
auxiliary heater has a heating capacity lower than a standard
heating capacity, which is defined as a necessary heating capacity
of the auxiliary heater for heating the heat-exchange fluid to a
target temperature in a case where (i) the auxiliary heater is
arranged to heat the heat-exchange fluid which has been heated in
the using-side heat exchanger, and (ii) the heating capacity of the
auxiliary heater and a heating capacity of the using-side heat
exchanger are used for heating the heat-exchange fluid.
18. The refrigerant cycle device according to claim 2, further
comprising a heating capacity adjusting portion configured to
adjust a capacity of the auxiliary heater for heating the
heat-exchange fluid so that a pressure of refrigerant in the
using-side heat exchanger becomes a target pressure.
19. The refrigerant cycle device according to claim 2, wherein the
auxiliary heater is an electric heater which generates heat by
receiving supply of electric power.
20. The refrigerant cycle device according to claim 2, wherein the
auxiliary heater is an auxiliary heat exchanger configured to heat
the heat-exchange fluid by utilizing heat of heat medium that cools
an external heat source.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Application No. 2011-192559 filed on Sep.
5, 2011 and No. 2012-169404 filed on Jul. 31, 2012.
TECHNICAL FIELD
[0002] The present disclosure relates to a vapor-compressing
refrigerant cycle device which can be suitably used as a
refrigerant cycle device for a vehicle.
BACKGROUND
[0003] Conventionally, in Patent Document 1 (JP 7-190574 A), a
vehicle air conditioner which performs heating of a vehicle
compartment is disclosed. Specifically, air to be blown into the
vehicle compartment is heated by using a vapor-compressing
refrigerant cycle. In the vehicle air conditioner of Patent
Document 1, the blown air, which is a heat-exchange fluid, passes
through a using-side heat exchanger and is heated by heat exchange
with high-pressure refrigerant discharged from a compressor of the
refrigerant cycle.
[0004] The vehicle air conditioner further includes an electric
heater as an auxiliary heater which is arranged downstream of the
using-side heat exchanger in an air flow direction to compensate
for a lack of an air heating capacity of the using-side heat
exchanger.
[0005] Because the vehicle air conditioner includes the electric
heater as the auxiliary heater, the electric heater may consume a
large amount of electric power in a largest heating operation or
the like of the electric heater. Thus, in the largest heating
operation or the like, an energy consumption amount of the electric
heater may be increased for performing an appropriate heating
operation, in which the blown air is heated to a desired
temperature.
[0006] Furthermore, a heating capacity of the auxiliary heater is
required to be so high that the auxiliary heater can compensate for
the lack of the air heating capacity of the using-side heat
exchanger sufficiently even in a case where the using-side heat
exchanger lacks its air heating capacity most. Therefore, the
auxiliary heater may become large in size, and the refrigerant
cycle device may be thereby increased in size and in manufacturing
cost as a whole.
SUMMARY
[0007] It is an object of the present disclosure to reduce an
energy consumption of a refrigerant cycle device which has a
using-side heat exchanger and an auxiliary heater to heat a
heat-exchange fluid.
[0008] According to an aspect of the present disclosure, a
refrigerant cycle device includes a compressor, a using-side heat
exchanger, an intermediate pressure passage, an exterior heat
exchanger and an auxiliary heater. The compressor has a suction
port through which low-pressure refrigerant is drawn, a discharge
port through which high-pressure refrigerant compressed in a
compression portion is discharged, and an intermediate pressure
port through which intermediate-pressure gas refrigerant is drawn
to be combined with refrigerant being compressed in the compression
portion. The using-side heat exchanger heats a heat-exchange fluid
by performing heat exchange between the heat-exchange fluid and the
high-pressure refrigerant discharged from the compressor.
Intermediate-pressure gas refrigerant obtained by decompression of
the high-pressure refrigerant flowing out of the using-side heat
exchanger is introduced into the intermediate pressure port through
the intermediate pressure passage. In the exterior heat exchanger,
low-pressure refrigerant, obtained by decompression of the
high-pressure refrigerant flowing out of the using-side heat
exchanger, evaporates. The exterior heat exchanger causes the
evaporated low-pressure refrigerant to flow to the suction port.
The auxiliary heater heats the heat-exchange fluid before or at the
same time as that the using-side heat exchanger heats the
heat-exchange fluid.
[0009] Because the refrigerant cycle device includes the auxiliary
heater which heats the heat-exchange fluid before or at the same
time as that the using-side heat exchanger heats the heat-exchange
fluid, an energy consumption of the auxiliary heater for heating
the heat-exchange fluid to a target temperature can be reduced as
compared with a case where the auxiliary heater heats the
heat-exchange fluid that has been heated by the using-side heat
exchanger.
[0010] Thus, the auxiliary heater increases a temperature of the
heat-exchange fluid flowing into the using-side heat exchanger, and
a heat radiation amount of refrigerant in the using-side heat
exchanger can be thereby decreased. Hence, a cycle balance of the
refrigerant cycle can be balanced so that a refrigerant pressure in
the using-side heat exchanger increases. Therefore, the
above-described reduction of the energy consumption in the
auxiliary heater can be achieved.
[0011] Accordingly, a temperature of refrigerant discharged from
the compressor can be increased, and a temperature difference
between refrigerant passing through the using-side heat exchanger
and the heat-exchange fluid flowing into the using-side heat
exchanger can be thus widen. Furthermore, a compression work amount
in a compression process from the intermediate port to the
discharge port of the compressor can be increased, and an enthalpy
difference between refrigerant flowing at a refrigerant inlet of
the using-side heat exchanger and refrigerant flowing at a
refrigerant outlet of the using-side heat exchanger can be
increased.
[0012] Hence, a capacity of the using-side heat exchanger for
heating the heat-exchange fluid can be improved. Therefore, the
heat-exchange fluid can be heated to the target temperature even
though a capacity of the auxiliary heater for heating the
heat-exchange fluid is reduced. As a result, the auxiliary heater
may have a relatively low heating capacity, and, in this case, an
energy consumption of the refrigerant cycle device, in which the
using-side heat exchanger and the auxiliary heater are capable of
heating the heat-exchange fluid, can be reduced.
[0013] According to another aspect of the present disclosure, a
refrigerant cycle device includes a compressor, a using-side heat
exchanger, a higher-pressure side expansion device, a gas-liquid
separation portion, a lower-pressure side expansion device, an
exterior heat exchanger and an auxiliary heater. The compressor has
a suction port through which low-pressure refrigerant is drawn, a
discharge port through which high-pressure refrigerant compressed
in a compression portion is discharged, and an intermediate
pressure port through which intermediate-pressure gas refrigerant
is drawn to be combined with refrigerant being compressed in the
compression portion. The using-side heat exchanger heats a
heat-exchange fluid by performing heat exchange between the
heat-exchange fluid and the high-pressure refrigerant discharged
from the compressor. The higher-pressure side expansion device is
configured to decompress the high-pressure refrigerant flowing out
of the using-side heat exchanger into intermediate-pressure
refrigerant. The gas-liquid separation portion is configured to
separate the intermediate-pressure refrigerant flowing out of the
higher-pressure side expansion device into intermediate-pressure
gas refrigerant and intermediate-pressure liquid refrigerant. The
gas-liquid separation portion causes the separated
intermediate-pressure gas refrigerant to flow to the intermediate
pressure port. The lower-pressure side expansion device is
configured to decompress the separated intermediate-pressure liquid
refrigerant flowing out of the gas-liquid separation portion into
low-pressure refrigerant. In the exterior heat exchanger, the
low-pressure refrigerant flowing out of the lower-pressure side
expansion device evaporates. The exterior heat exchanger causes the
evaporated low-pressure refrigerant to flow to the suction port.
The auxiliary heater heats the heat-exchange fluid before or at the
same time as that the using-side heat exchanger heats the
heat-exchange fluid.
[0014] In this case, the refrigerant cycle device is a two stage
expansion-type gas injection cycle in which the higher-pressure
side expansion device, the gas-liquid separator and the
lower-pressure side expansion device are combined. In this case,
operational effects similar to those of the aspect of the present
disclosure described firstly can be obtained.
[0015] According to another aspect of the present disclosure, a
refrigerant cycle device includes a compressor, a using-side heat
exchanger, a refrigerant branch portion, a first expansion device,
an inner heat exchanger, a second expansion device, an exterior
heat exchanger and an auxiliary heater. The compressor has a
suction port through which low-pressure refrigerant is drawn, a
discharge port through which high-pressure refrigerant compressed
in a compression portion is discharged, and an intermediate
pressure port through which intermediate-pressure gas refrigerant
is drawn to be combined with refrigerant being compressed in the
compression portion. The using-side heat exchanger heats a
heat-exchange fluid by performing heat exchange between the
heat-exchange fluid and the high-pressure refrigerant discharged
from the compressor. At the refrigerant branch portion, a
refrigerant passage of the high-pressure refrigerant flowing out of
the using-side heat exchanger branches into a first refrigerant
passage and a second refrigerant passage. The first expansion
device is provided in the first refrigerant passage to decompress
the high-pressure refrigerant flowing out of the using-side heat
exchanger into intermediate-pressure refrigerant. In the inner heat
exchanger, the high-pressure refrigerant flowing from the
using-side heat exchanger through the second refrigerant passage
exchanges heat with the intermediate-pressure refrigerant
decompressed by the first expansion device. The inner heat
exchanger causes the heat-exchanged intermediate-pressure
refrigerant to flow to the intermediate pressure port. The second
expansion device is configured to decompress the heat-exchanged
high-pressure refrigerant flowing out of the inner heat exchanger
into low-pressure refrigerant. In the exterior heat exchanger, the
low-pressure refrigerant flowing out of the second expansion device
evaporates. The exterior heat exchanger causes the evaporated
low-pressure refrigerant to flow to the suction port. The auxiliary
heater heats the heat-exchange fluid before or at the same time as
that the using-side heat exchanger heats the heat-exchange
fluid.
[0016] In this case where the refrigerant cycle device is an inner
heat-exchange gas injection cycle, operational effects similar to
those of the aspect of the present disclosure described firstly can
be obtained.
[0017] The auxiliary heater may be arranged upstream of the
using-side heat exchanger in a flow direction of the heat-exchange
fluid to heat the heat-exchange fluid before the heat-exchange
fluid being heated by the using-side heat exchanger.
[0018] The auxiliary heater and the using-side heat exchanger may
be arranged in a direction perpendicular to a flow direction of the
heat-exchange fluid, and may be integrated with each other to heat
the heat-exchange fluid at the same time.
[0019] The auxiliary heater may have a heating capacity lower than
a standard heating capacity, which is defined as a necessary
heating capacity of the auxiliary heater for heating the
heat-exchange fluid to the target temperature in a case where (i)
the auxiliary heater is arranged to heat the heat-exchange fluid
which has been heated in the using-side heat exchanger, and (ii)
the heating capacity of the auxiliary heater and a heating capacity
of the using-side heat exchanger are used for heating the
heat-exchange fluid.
[0020] Because the auxiliary heater has the heating capacity lower
than the standard heating capacity, an energy consumption in the
auxiliary heater can be reduced reliably as compared with a case
where the auxiliary heater heats the heat-exchange fluid after
being heated in the using-side heat exchanger. Moreover, the
auxiliary heater can be downsized, and the refrigerant cycle device
can be thereby reduced in size and in manufacturing cost as a
whole.
[0021] The refrigerant cycle device may further include a heating
capacity adjusting portion configured to adjust the heating
capacity of the auxiliary heater so that a pressure of the
heat-exchange fluid in the using-side heat exchanger becomes a
target pressure.
[0022] In this case, because the heating capacity adjusting portion
adjusts the heating capacity of the auxiliary heater so that the
pressure of the heat-exchange fluid in the using-side heat
exchanger becomes the target pressure, the temperature of the
heat-exchange fluid can be increased to the target temperature
easily by setting the target pressure depending on the target
temperature of the heat-exchange fluid.
[0023] The auxiliary heater may be an electric heater which
generates heat by receiving supply of electric power. In this case,
the electric heater, which has a heating capacity lower than the
standard heating capacity, includes an electric heater which
generates a relatively small heat amount (wattage) when a
predetermined voltage is applied to the electric heater.
[0024] Alternatively, the auxiliary heater may be an auxiliary heat
exchanger which heats the heat-exchange fluid by using heat medium,
which cools an external heat source, as a heat source. In this
case, the auxiliary heat exchanger, which has a heating capacity
lower than the standard heating capacity, includes an auxiliary
heat exchanger which has a relatively small area in which the
heat-exchange fluid is heated through heat exchange.
[0025] When the auxiliary heater is the electric heater as
described above, the heating capacity adjusting portion may adjust
the heating capacity of the electric heater by adjusting a supply
of the electric power to the electric heater.
[0026] When the auxiliary heater is the auxiliary heat exchanger as
described above, the heating capacity adjusting portion may adjust
the heating capacity of the auxiliary heat exchanger by adjusting a
flow amount of the heat medium flowing into the auxiliary heat
exchanger.
[0027] The heating capacity adjusting portion may activate the
auxiliary heater when the capacity of the using-side heat exchanger
for heating the heat-exchange fluid is incapable of being
sufficient by a heating capacity control of the using-side heat
exchanger.
[0028] In this case, an operation amount of the auxiliary heater
can be reduced to requisite minimum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The disclosure, together with additional objectives,
features and advantages thereof, will be best understood from the
following description, the appended claims and the accompanying
drawings, in which:
[0030] FIG. 1 is a schematic diagram showing a refrigerant circuit
of a heat pump cycle for a vehicle air conditioner in a cooling
mode and in a dehumidifying-heating mode, according to a first
embodiment of the present disclosure;
[0031] FIG. 2 is a schematic diagram showing a refrigerant circuit
of the heat pump cycle for the vehicle air conditioner in a heating
mode, according to the first embodiment;
[0032] FIG. 3A is a schematic perspective view showing a gas-liquid
separator for the heat pump cycle of the vehicle air conditioner
according to the first embodiment;
[0033] FIG. 3B is a top view showing the gas-liquid separator for
the heat pump cycle of the vehicle air conditioner according to the
first embodiment;
[0034] FIG. 4 is a flowchart showing a control process of the
vehicle air conditioner according to the first embodiment;
[0035] FIG. 5 is a flowchart showing a part of the control process
of the vehicle air conditioner in the heating mode, according to
the first embodiment;
[0036] FIG. 6 is a flowchart showing a part of the control process
of the vehicle air conditioner in a subcool control of the heating
mode, according to the first embodiment;
[0037] FIG. 7 is a flowchart showing a part of the control process
of the vehicle air conditioner in a quality control (dryness
control) of the heating mode, according to the first
embodiment;
[0038] FIG. 8 is a flowchart showing a part of the control process
of the vehicle air conditioner in a PTC-heater control of the
heating mode, according to the first embodiment;
[0039] FIG. 9 is a flowchart showing a part of the control process
of the vehicle air conditioner in the heating mode, according to
the first embodiment;
[0040] FIG. 10 is a Mollier diagram showing a refrigerant state in
the heat pump cycle in the heating mode, according to the first
embodiment;
[0041] FIG. 11 is a Mollier diagram showing a refrigerant state in
a heat pump cycle in a heating mode, according to a comparative
example;
[0042] FIG. 12 is a schematic diagram showing a refrigerant circuit
of a heat pump cycle for a vehicle air conditioner in a heating
mode, according to a second embodiment of the present
disclosure;
[0043] FIG. 13 is a flowchart showing a part of a control process
of a vehicle air conditioner in a PTC-heater control of a heating
mode, according to a third embodiment of the present
disclosure;
[0044] FIG. 14 is a schematic diagram showing a refrigerant circuit
of a heat pump cycle for a vehicle air conditioner in a heating
mode, according to a fourth embodiment of the present
disclosure;
[0045] FIG. 15 is a Mollier diagram showing a refrigerant state in
the heat pump cycle in the heating mode, according to the fourth
embodiment; and
[0046] FIG. 16 is a schematic diagram showing a refrigerant circuit
of a heat pump cycle for a vehicle air conditioner in a heating
mode, according to a fifth embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0047] Embodiments of the present disclosure will be described
hereinafter referring to drawings. In the embodiments, a part that
corresponds to a matter described in a preceding embodiment may be
assigned the same reference numeral, and redundant explanation for
the part may be omitted. When only a part of a configuration is
described in an embodiment, another preceding embodiment may be
applied to the other parts of the configuration. The parts may be
combined even if it is not explicitly described that the parts can
be combined. The embodiments may be partially combined even if it
is not explicitly described that the embodiments can be combined,
provided there is no harm in the combination.
First Embodiment
[0048] A first embodiment of the present disclosure will be
described with reference to FIGS. 1 to 10. In the first embodiment,
a refrigerant cycle device of the present disclosure is used for a
vehicle air conditioner 1 of an electrical vehicle in which driving
force is obtained from an electric motor for vehicle running. In
the vehicle air conditioner 1, the refrigerant cycle device
functions to heat or cool air to be blown into a vehicle
compartment that is a space (air conditioning space) to be
air-conditioned. Therefore, the blown air is an example of a fluid
(heat-exchange fluid) to be heat-exchanged with refrigerant.
[0049] The refrigerant cycle device includes a heat pump cycle 10
(vapor-compressing refrigerant cycle) in which its refrigerant
circuit can be switched depending on an air conditioning mode
including a cooing mode, a dehumidifying-heating mode
(dehumidifying mode) and a heating mode. In the cooling mode, a
refrigerant circuit shown in FIG. 1 is selected, and the blown air
is cooled to cool the vehicle compartment. Also in the
dehumidifying-heating mode, the refrigerant circuit shown in FIG. 1
is selected, and the vehicle compartment is dehumidified and
heated. In the heating mode, a refrigerant circuit shown in FIG. 2
is selected, and the blown air is heated to heat the vehicle
compartment.
[0050] When a hydrofluorocarbon (HFC) refrigerant (e.g., R-134a) is
adopted as refrigerant used for the heat pump cycle 10, the heat
pump cycle 10 is a vapor-compressing subcritical refrigerant cycle.
Thus, a pressure Pd having a highest pressure in the heat pump
cycle 10 is lower than a critical pressure of the refrigerant.
Alternatively, a hydrofluoro-olefine (HFO) refrigerant (e.g.,
R1234yf) may be adopted as the refrigerant, for example. The
refrigerant contains oil to lubricate a compressor 11 of the heat
pump cycle 10, and a part of the oil circulates together with the
refrigerant in the heat pump cycle 10.
[0051] The compressor 11 of the heat pump cycle 10 is arranged
inside a hood of the vehicle, and draws and compresses refrigerant
to discharge the compressed refrigerant. The compressor 11 is, for
example, an electrical two-stage compressor including a housing
used as an outer shell of the compressor 11, higher-stage and
lower-stage fixed displacement compression mechanisms accommodated
inside the housing, an electric motor accommodated inside the
housing to rotationally drive the two compression mechanisms.
Refrigerant is compressed at higher pressure in the higher-stage
compression mechanism than in the lower-stage compression
mechanism.
[0052] The housing of the compressor 11 has a suction port 11a
through which low-pressure refrigerant is drawn into the
lower-stage compression mechanism from outside the housing, an
intermediate pressure port 11b through which intermediate-pressure
refrigerant is drawn into the housing to be mixed with refrigerant
flowing from the lower-stage compression mechanism to the
higher-stage compression mechanism, and a discharge port 11c
through which high-pressure refrigerant is discharged from the
higher-stage compression mechanism to outside the housing.
[0053] More specifically, the intermediate pressure port 11b is
connected to a refrigerant discharge side of the lower-stage
compression mechanism, in other words, the intermediate pressure
port 11b is connected to a refrigerant, suction side of the
higher-stage compression mechanism. Various types of compression
mechanisms, such as a scroll-type compression mechanism, a
vane-type compression mechanism, and a rolling piston-type
compression mechanism, may be adopted as the lower-stage and the
higher-stage compression mechanisms.
[0054] An operation (rotation rate) of the electric motor of the
compressor 11 is controlled by a control signal outputted from an
air conditioner controller 40 (A/C ECU), and an alternating-current
motor or a direct-current motor may be adopted as the electric
motor. By the control of the rotation rate of the electric motor, a
refrigerant discharge capacity of the compressor 11 is controlled.
Thus, in the present embodiment, the electric motor is used as an
example of a discharge capacity changing portion of the compressor
11 which changes the refrigerant discharge capacity of the
compressor 11.
[0055] The compressor 11 includes the two compression mechanisms
accommodated in the single housing of the compressor 11 in the
present embodiment, but a configuration of the compressor 11 is not
limited to this. Alternatively, the compressor 11 may accommodate a
single fixed displacement compression mechanism and an electric
motor rotationally driving the single compression mechanism, if
intermediate-pressure refrigerant can be drawn into the compressor
11 and can be mixed with refrigerant being in a compression process
in the compressor 11.
[0056] Moreover, two compressors: higher-stage and lower-stage
compressors may be arranged separately in series instead of the
above-described configuration of the compressor 11, and the two
compressors may be adopted as the single two-stage compressor 11.
In this case, a suction port of the lower-stage compressor may be
adopted as the suction port 11a, and a discharge port of the
higher-stage compressor may be adopted as the discharge port 11c.
The intermediate pressure port 11b may be provided in a part
connecting a discharge port of the lower-stage compressor and a
suction port of the higher-stage compressor.
[0057] As shown in FIGS. 1 and 2, the discharge port 11c of the
compressor 11 is connected to a refrigerant inlet side of an
interior condenser 12. The interior condenser 12 is arranged inside
a casing 31 (air conditioning case) of an interior air conditioning
unit 30 of the vehicle air conditioner 1 to function as a radiator
in which high-temperature and high-pressure refrigerant discharged
from the higher-stage compression mechanism of the compressor 11
radiates heat. The interior condenser 12 is used as an example of a
using-side heat exchanger which heats air having passed through an
interior evaporator 23 described later.
[0058] A refrigerant outlet side of the interior condenser 12 is
connected to an inlet of a first expansion valve 13 (higher-stage
expansion valve) used as an example of a higher-pressure side
expansion device. The higher-pressure side expansion device (13)
decompresses high-pressure refrigerant flowing out of the interior
condenser 12 so that the high-pressure refrigerant changes into
intermediate-pressure refrigerant. The first expansion valve 13 has
an electrical variable throttle mechanism. The electrical variable
throttle mechanism includes a valve body in which an open degree of
the valve body is changeable, and an electrical actuator having a
step motor which changes the open degree of the valve body.
[0059] When the first expansion valve 13 is set at a decompression
state in which the first expansion valve 13 decompresses
refrigerant, an open degree of the first expansion valve 13 is
regulated within a range from .phi.0.5 mm to .phi.3 mm in
cross-section diameter. When the first expansion valve 13 is fully
open, the open degree is set to be approximately .phi.10 mm in
cross-section diameter. The first expansion valve 13 in the fully
open state does not decompress refrigerant. An operation of the
first expansion valve 13 is controlled by a control signal
outputted from the air conditioning controller 40.
[0060] An outlet side of the first expansion valve 13 is connected
to an inflow port 14b of a gas-liquid separator 14. The gas-liquid
separator 14 is used as an example of a gas-liquid separation
portion which separates intermediate-pressure refrigerant into gas
refrigerant and liquid refrigerant. Here, the intermediate-pressure
refrigerant has passed through the interior condenser 12 and been
compressed in the first expansion valve 13. The gas-liquid
separator 14 is a centrifugal separator which separates refrigerant
into gas and liquid by utilizing centrifugal force.
[0061] A detailed configuration of the gas-liquid separator 14 will
be described referring to FIGS. 3A and 3B. The up-down arrow shown
in FIG. 3A indicates a vertical direction when the gas-liquid
separator 14 is mounted to the vehicle air conditioner 1.
[0062] The gas-liquid separator 14 of the present embodiment
includes a main body part 14a, the inflow port 14b, a gas outflow
port 14c and a liquid outflow port 14d. The main body part 14a has
a hollow and almost cylindrically bottomed shape with a circular
cross-section, and extends in a direction (e.g., the vertical
direction) perpendicular to the diameter direction of the circular
cross-section. The inflow port 14b has an inflow opening 14e
through which intermediate-pressure refrigerant is introduced into
the main body part 14a. The gas outflow port 14c has a gas outflow
opening 14f through which gas refrigerant flows out of the main
body part 14a, and the liquid outflow port 14d has a liquid outflow
opening 14g through which liquid refrigerant flows out of the main
body part 14a.
[0063] A diameter of the main body part 14a is set at a value from
one and half times to three times as large as diameters of
refrigerant pipes connected to the ports 14b to 14d. Accordingly,
the gas-liquid separator 14 is miniaturized.
[0064] A volume of the main body part 14a of the gas-liquid
separator 14 is set to be smaller than a surplus refrigerant volume
that is obtained by subtracting a necessary refrigerant volume from
a sealed total refrigerant volume. Here, the sealed total
refrigerant volume is a liquid refrigerant volume converted from a
total volume of gas and liquid refrigerant enclosed in the heat
pump cycle 10, and the necessary refrigerant volume is a liquid
refrigerant volume converted from a necessary volume of refrigerant
for optimizing performance of the heat pump cycle 10. In other
words, the volume of the gas-liquid separator 14 of the present
embodiment is set such that the gas-liquid separator 14 cannot
store surplus refrigerant therein substantially, even when a flow
rate of refrigerant circulating in the heat pump cycle 10 is
changed due to load variation of the heat pump cycle 10.
[0065] The inflow port 14b is connected to a lateral surface of the
cylindrical main body part 14a. As shown in FIG. 3B, the inflow
port 14b extends in a tangential direction of a cross-sectional
circle of the main body part 14a when viewed from above the
gas-liquid separator 14. The inflow port 14b has the inflow opening
14e at an end of the inflow port 14b opposite from the main body
part 14a. The inflow port 14b may not necessarily extend in radial
direction (e.g., a horizontal direction), and may extend at some
angle with respect to the radial direction.
[0066] The gas outflow port 14c is connected to the main body part
14a at an upper end surface (top surface) of the main body part 14a
in an axial direction of the main body part 14a, and the gas
outflow port 14c extends through the top surface of the main body
part 14a coaxially with the main body part 14a. The gas outflow
port 14c is provided with the gas outflow opening 14f at an upper
end part of the gas outflow port 14c, and a lower end part of the
gas outflow port 14c is located downward of a connection part
between the main body part 14a and the gas outflow port 14c.
[0067] The liquid outflow port 14d is connected to the main body
part 14a at a lower end surface (bottom surface) of the main body
part 14a in its axial direction, and the liquid outflow port 14d
extends downward from the bottom surface of the main body part 14a
coaxially with the main body part 14a. A lower end part of the
liquid outflow port 14d has the liquid outflow opening 14g.
[0068] Refrigerant flowing into the gas-liquid separator 14 from
the inflow opening 14e of the inflow port 14b flows and swirls
along a cylindrical inner surface of the main body part 14a, and
the refrigerant is separated into gas refrigerant and liquid
refrigerant by utilizing centrifugal force caused by the swirl
flow. Subsequently, the liquid refrigerant obtained by this
separation falls down in the main body part 14a by gravity.
[0069] The dropt liquid refrigerant flows out of the liquid outflow
opening 14g of the liquid outflow port 14d, and the gas refrigerant
obtained by the separation flows out of the gas outflow opening 14f
of the gas outflow port 14c. In FIGS. 3A and 3B, the lower end
surface (bottom surface) of the main body part 14a has a circular
shape. Alternatively, the main body part 14a may be formed into a
tapered shape in which a diameter of the main body part 14a is
gradually reduced downward, and a lowest part of the tapered main
body part 14a may be connected to the liquid outflow port 14d.
[0070] As shown in FIGS. 1 and 2, the liquid outflow port 14c of
the gas-liquid separator 14 is coupled to the intermediate pressure
port 11b of the compressor 11 via an intermediate pressure passage
15. A first open-close valve 16a (intermediate pressure-side
open-close valve) is arranged in the intermediate pressure passage
15, and the first open-close valve 16a is an electromagnetic valve
which opens or closes the intermediate pressure passage 15. An
operation of the first open-close valve 16a is controlled by a
control signal outputted from the air conditioning controller
40.
[0071] The first open-close valve 16a is used also as a check valve
which allows refrigerant only to flow from the gas outflow port 14c
of the gas-liquid separator 14 to the intermediate pressure port
11b of the compressor 11 when the intermediate pressure passage 15
is open. Accordingly, when the first open-close valve 16a opens the
intermediate pressure passage 15, refrigerant is prevented from
flowing back from the compressor 11 to the gas-liquid separator
14.
[0072] Moreover, the first open-close valve 16a functions also to
switch the refrigerant circuit of the heat pump cycle 10 by opening
or closing the intermediate pressure passage 15. Thus, the first
open-close valve 16a in the present embodiment is used also as an
example of a refrigerant circuit switching portion which switches
the refrigerant circuit of the heat pump cycle 10.
[0073] The liquid outflow port 14d of the gas-liquid separator 14
is connected to an inlet side of a lower-pressure side fixed
throttle 17, and an outlet side of the fixed throttle 17 is
connected to a refrigerant inlet side of an exterior heat exchanger
20. The fixed throttle 17 is used as an example of a lower-pressure
side expansion device which decompresses liquid refrigerant flowing
out of the gas-liquid separator 14 such that a pressure of the
liquid refrigerant is reduced to be low-pressure refrigerant. A
nozzle having a fixed open degree or an orifice can be adopted as
the fixed throttle 17, for example.
[0074] In the fixed throttle 17 such as the nozzle or the orifice,
a passage cross-section is drastically decreased or drastically
increased. Thus, a flow rate of refrigerant flowing through the
fixed throttle 17 and a quality (dryness) X of refrigerant upstream
of the fixed throttle 17 can be self-adjusted (balanced) depending
on a pressure difference between the upstream (inlet) side and a
downstream (outlet) side of the fixed throttle 17.
[0075] Specifically, when the pressure difference is relatively
high, the quality X of refrigerant upstream of the fixed throttle
17 is balanced to be increased in accordance with decrease of a
necessary flow amount of refrigerant circulating in the heat pump
cycle 10. On the other hand, when the pressure difference is
relatively low, the quality X of refrigerant upstream of the fixed
throttle 17 is balanced to be decreased in accordance with increase
of the necessary flow amount of refrigerant circulating in the heat
pump cycle 10.
[0076] When the quality X of refrigerant upstream of the fixed
throttle 17 is high, and when the exterior heat exchanger 20 is
used as an evaporator in which refrigerant is evaporated by
absorbing heat, a heat absorption amount (refrigeration capacity)
in the exterior heat exchanger 20 may decrease, and a coefficient
of performance (COP) of the heat pump cycle 10 may thereby
decrease.
[0077] Thus, in the present embodiment, the fixed throttle 17 is
configured such that the quality X of refrigerant upstream of the
fixed throttle 17 is always set to be equal to or lower than 0.1
regardless of change of the necessary flow amount of refrigerant
circulating in the heat pump cycle 10 due to the load variation of
the heat pump cycle 10 in the heating mode. That is, when a
refrigerant circulation rate and the pressure difference between
the inlet side and the outlet side of the fixed throttle 17 are
changed within an expected range due to the load variation of the
heat pump cycle 10, the quality X of refrigerant upstream of the
fixed throttle 17 is adjusted to be equal to or lower than 0.1. As
a result, the COP of the heat pump cycle 10 can be improved.
[0078] The liquid outflow port 14d of the gas-liquid separator 14
is further connected to a bypass passage 18 through which liquid
refrigerant flowing out of the gas-liquid separator 14 bypasses the
fixed throttle 17 and is guided toward the exterior heat exchanger
20. A second open-close valve 16b (low pressure-side open-close
valve) is provided in the bypass passage 18. The second open-close
valve 16b is an electromagnetic valve, in which its basic structure
is equivalent to a basic structure of the first open-close valve
16a. An operation of the second open-close valve 16b is controlled
by a control signal outputted from the air conditioner controller
40.
[0079] A pressure loss generated when refrigerant flows through the
second open-close valve 16b is extremely lower than a pressure loss
generated when refrigerant flows through the fixed throttle 17.
Hence, when the second open-close valve 16b is open, refrigerant
from the interior condenser 12 flows into the exterior heat
exchanger 20 through the bypass passage 18. On the other hand, when
the second open-close valve 16b is closed, refrigerant from the
interior condenser 12 flows into the exterior heat exchanger 20
through the fixed throttle 17.
[0080] Thus, the second open-close valve 16b can cause the
refrigerant circuit of the heat pump cycle 10 to be switched.
Therefore, the second open-close valve 16b of the present
embodiment is used as an example of the refrigerant circuit
switching portion together with the first open-close valve 16a.
[0081] An electrical three-way valve may be used as such
refrigerant circuit switching portion (16b), which switches between
a refrigerant circuit connecting an outlet side of the liquid
outflow port 14d of the gas-liquid separator 14 to the inlet side
of the fixed throttle 17 and a refrigerant circuit connecting the
outlet side of the liquid outflow port 14d of the gas-liquid
separator 14 to an inlet side of the bypass passage 18.
[0082] The exterior heat exchanger 20 is arranged in the hood of
the vehicle, and refrigerant flowing through the exterior heat
exchanger 20 exchanges heat with outside air blown by a blower fan
21. The exterior heat exchanger 20 functions as an evaporator, in
which low-pressure refrigerant evaporates and exerts its heat
absorption effect in the heating mode, and functions also as a
radiator, in which high-pressure refrigerant radiates heat in the
cooling mode or the like.
[0083] A refrigerant outlet side of the exterior heat exchanger 20
is connected to a refrigerant inlet side of a second expansion
valve 22 (cooling expansion valve) which decompresses refrigerant
flowing from the exterior heat exchanger 20 to the interior
evaporator 23 in the cooling mode or the like. A basic structure of
the second expansion valve 22 is similar to that of the first
expansion valve 13, and an operation of the second expansion valve
22 is controlled by a control signal outputted from the air
conditioning controller 40.
[0084] An outlet side of the second expansion valve 22 is connected
to a refrigerant inlet side of the interior evaporator 23. The
interior evaporator 23 is arranged upstream of the interior
condenser 12 in an air flow direction in the casing 31 of the air
conditioning unit 30. The interior evaporator 23 is used as an
example of an evaporator which cools air by utilizing a
heat-absorption effect caused by evaporation of refrigerant flowing
through the interior evaporator 23 in the cooling mode, the
dehumidifying-heating mode or the like.
[0085] A refrigerant outlet side of the interior evaporator 23 is
connected to an inlet side of an accumulator 24. The accumulator 24
is a low pressure-side gas-liquid separator which separates
refrigerant into gas refrigerant and liquid refrigerant and
accumulates surplus refrigerant therein. An outlet of the
accumulator 24, through which the gas refrigerant flows out of the
accumulator 24, is connected to the suction port 11a of the
compressor 11. The interior evaporator 23 is connected to the
suction port 11a of the compressor 11 via the accumulator 24 such
that refrigerant flows from the interior evaporator 23 through the
accumulator 24 to the suction port 11a of the compressor 11.
[0086] The refrigerant outlet side of the exterior heat exchanger
20 is further connected to a bypass passage 25, through which
refrigerant flowing out of the exterior heat exchanger 20 bypasses
the second expansion valve 22 and the interior evaporator 23 to be
guided toward the inlet side of the accumulator 24. A third
open-close valve 16c (cooling open-close valve) is provided in the
bypass passage 25 to open or close the bypass passage 25.
[0087] A basic structure of the third open-close valve 16c is
similar to that of the second open-close valve 16b, and an
operation of the third open-close valve 16c is controlled by a
control signal outputted from the air conditioning controller 40. A
pressure loss generated when refrigerant flows through the third
open-close valve 16c is extremely lower than a pressure loss
generated when refrigerant flows through the second expansion valve
22.
[0088] Hence, when the third open-close valve 16c is open,
refrigerant flowing out of the exterior heat exchanger 20 flows
into the accumulator 24 via the bypass passage 25. In this case,
the second expansion valve 22 may be fully open.
[0089] When the third open-close valve 16c is closed, refrigerant
flowing out of the exterior heat exchanger 20 flows into the
interior evaporator 23 via the second expansion valve 22.
Therefore, the third open-close valve 16c can cause the refrigerant
circuit of the heat pump cycle 10 to be switched, and the third
open-close valve 16c is used as an example of the refrigerant
circuit switching portion together with the first and second
open-close valves 16a, 16b.
[0090] Next, the air conditioning unit 30 will be described with
reference to FIGS. 1 and 2. The air conditioning unit 30 is
arranged inside an instrumental panel positioned at a front end
part of the vehicle compartment. The air conditioning unit 30
includes the casing 31 which constitutes an outer shell of the air
conditioning unit 30, and defines therein an air passage through
which air is blown toward the vehicle compartment. In the air
passage, a blower 32, the interior condenser 12 and the interior
evaporator 32 are accommodated, for example.
[0091] The casing 31 accommodates an inside/outside air switching
device 33, and the inside/outside air switching device 33 is
located in an upstream end part of the casing 31. The
inside/outside air switching device 33 is used for selectively
introducing inside air (REC) (i.e. air inside the vehicle
compartment) or/and outside air (FRS) into the casing 31.
Specifically, the inside/outside air switching device 33
continuously adjusts an opening area of an inside air port, through
which inside air is introduced, and an opening area of an outside
air port, through which outside air is introduced, by using an
inside/outside air switching door. Accordingly, the inside/outside
air switching device 33 continuously changes a ratio between a flow
amount of the inside air and a flow amount of the outside air.
[0092] The blower 32 is arranged downstream of the inside/outside
air switching device 33 in the air flow direction, and the blower
32 blows air, which has been introduced via the inside/outside air
switching device 33, toward the vehicle compartment. The blower 32
is an electrical blower which drives a centrifugal multi-blade fan
(sirocco fan) by using an electric motor, and a rotation rate (air
blowing amount) of the blower 32 is controlled by a control voltage
outputted from the air conditioning controller 40.
[0093] The interior evaporator 23, a PTC heater 50 (electric
heater) and the interior condenser 12 are arranged downstream of
the blower 32 in the air flow direction in the order: the interior
evaporator 23.fwdarw.the PTC heater 50.fwdarw.the interior
condenser 12. In other words, the interior evaporator 23 is
arranged upstream of the PTC heater 50 in the air flow direction,
and the PTC heater 50 is arranged upstream of the interior
condenser 12 in the air flow direction.
[0094] The PTC heater 50 is used as an example of an auxiliary
heater which heats air in order to compensate for a lack of a
capacity of the interior condenser 12 for heating air that is to be
blown into the vehicle compartment. More specifically, the PTC
heater 50 includes a positive temperature coefficient element (PTC
element), and the PTC element receives a supply of electric power
from the air conditioning controller 40 to generate heat, thereby
heating air that is to flow into the interior condenser 12. A heat
generation amount of the PTC heater 50 is increased in accordance
with increase of the supplied electric power.
[0095] The air conditioning controller 40 of the present embodiment
is capable of switching an operation mode of the PTC heater 50. The
operation mode of the PTC heater 50 includes a HIGH mode in which
the PTC heater 50 receives electric power with a high voltage
(e.g., 12V) from the air conditioning controller 40 to output a
large heat amount, a LOW mode in which the PTC heater 50 receives
electric power with a low voltage (e.g., 6V) from the air
conditioning controller 40 to output a small heat amount, and an
OFF mode in which the PTC heater 50 is not energized.
[0096] Here, an air heating capacity of the PTC heater 50 of the
present embodiment will be described. The inventor has studied a
case where a PTC heater is arranged so as to heat air which has
been heated in the interior condenser 12. In other words, the PTC
heater is arranged downstream of the interior condenser 12 instead
of the PTC heater 50 arranged upstream of the interior condenser
12. Then, air is heated to a target temperature by using heating
capacities of both the interior condenser 12 and the PTC
heater.
[0097] In this case, when the air heating capacity of the interior
condenser 12 is smallest, a necessary heating capacity (largest
heating capacity) of the PTC heater for heating the air to the
target temperature is approximately 2kW. In other words, the PTC
heater is required to output heat of 2kW when the PTC heater is
energized with a rated voltage of 12V, for example. The largest
hating capacity of the PTC heater is referred to as a standard
heating capacity hereinafter.
[0098] In the present embodiment, the, PTC heater 50 has an air
heating capacity lower than the standard heating capacity. For
example, the PTC heater 50 generates heat of approximately 800W,
which is equal to or smaller than a half of the standard heating
capacity, when the PTC heater 50 is energized with a rated voltage
of 12V.
[0099] In the casing 31, a bypass air passage 35 is provided,
through which air having passed through the interior evaporator 23
bypasses the interior condenser 12 and the PTC heater 50, and an
air mix door 34 is arranged downstream of the interior evaporator
23 and upstream of the interior condenser 12 in the air flow
direction.
[0100] The air mix door 34 of the present embodiment adjusts a
ratio between a flow amount of air, which passes through the PTC
heater 50 and the interior condenser 12, and a flow amount of air,
which passes through the bypass air passage 35. Hence, the air mix
door 34 is used as an example of a flow amount adjusting portion
which adjusts a flow amount (air amount) flowing into the interior
condenser 12, and is used also as an example of a heat exchange
capacity adjusting portion which adjusts a heat exchange capacity
of the interior condenser 12.
[0101] A mixing space 36 is provided downstream of the interior
condenser 12 and of the bypass air passage 35 in the air flow
direction in the casing 31. Heated air, which has exchanged heat
with refrigerant in the interior condenser 12, and non-heated air,
which has passed through the bypass air passage 35, are mixed with
each other in the mixing space 36. The mixing space 36 is used as
an air mix chamber in which heated air (warm air) and non-heated
air (cool air) are mixed with each other.
[0102] Thus, the air mix door 34 adjusts the ratio between the flow
amount of air passing through the interior condenser 12 and the
flow amount of air passing through the bypass air passage 35, so
that a temperature of air in the mixing space 36 is adjusted. The
air mix door 34 is driven by a servomotor, and an operation of the
servomotor is controlled by a control signal outputted from the air
conditioning controller 40.
[0103] A downstream part of the casing 31 in the air flow direction
has air outlet openings through which air conditioned in the mixing
space 36 is blown out toward the vehicle compartment, and the
vehicle compartment is the space (air conditioning space) to be
air-conditioned. The air outlet openings include a defroster
opening 37a through which conditioned air is blown toward an inner
surface of a windshield of the vehicle, a face opening 37b through
which conditioned air is blown toward an upper part of a passenger
in the vehicle compartment, and a foot openings 37c through which
conditioned air is blown toward a foot area of the passenger.
[0104] A defroster door 38a, a face door 38b and a foot door 38c
are arranged upstream of the defroster opening 37a, the face
opening 37b and the foot opening 37c in the air flow direction,
respectively. The defroster door 38a, the face door 38b and the
foot door 38c adjust opening areas of the defroster opening 37a,
the face opening 37b and the foot opening 37c, respectively.
[0105] The defroster door 38a, the face door 38b and the foot door
38c open or close their openings 37a, 37b, 37c, respectively,
thereby being used as examples of an air outlet mode switching
portion which switches an air outlet mode. These three doors 38a,
38b, 38c are driven via a link mechanism or the like by a
servomotor in which an operation of the servomotor is controlled by
a control signal outputted from the air conditioning controller
40.
[0106] Downstream sides of the defroster opening 37a, the face
opening 37b and the foot opening 37c in the air flow direction are
connected respectively to a defroster air outlet, a face air outlet
and a foot air outlet through air passages of ducts. The defroster
air outlet, the face air outlet and the foot air outlet are
provided in the vehicle compartment.
[0107] The air outlet mode includes a face mode in which the face
opening 37b is fully open such that conditioned air is blown from
the face air outlet toward the upper part of the passenger in the
vehicle compartment, a bi-level mode in which both the face opening
37b and the foot opening 37c are open such that conditioned air is
blown toward the upper part and the foot area of the passenger, and
a foot mode in which the foot opening 37c is fully open and the
defroster opening 37a is slightly open such that conditioned air is
blown mainly from the foot air outlet.
[0108] Next, an electrical control portion of the present
embodiment will be described. The air conditioning controller 40
includes a known microcomputer and its peripheral circuit, and the
microcomputer includes a central processing unit (CPU), a read-only
memory (ROM) and a random access memory (RAM). The air conditioning
controller 40 performs various calculation and processes based on
an air conditioning program stored in the ROM, and controls
operations of various air conditioning components (e.g., the
compressor 11, the open-close valves 16a, 16b, 16c, the blower 32
and the PTC heater 50) connected to an output side of the air
conditioning controller 40.
[0109] An input side of the air conditioning controller 40 is
connected to a sensor group 41 having various air conditioning
sensors. The sensor group 41 includes an inside air sensor which
detects a temperature inside the vehicle compartment, an outside
air sensor which detects a temperature of outside air, a solar
radiation sensor which detects a solar radiation amount entering
into the vehicle compartment, an evaporator temperature sensor
which detects a temperature (temperature of the interior evaporator
23) of air flowing out of the interior evaporator 23, a discharge
pressure sensor which detects a pressure of high-pressure
refrigerant discharged from the compressor 11, a condenser
temperature sensor which detects a temperature of refrigerant
flowing out of the interior condenser 12, and an inlet pressure
sensor which detects a pressure of refrigerant drawn into the
compressor 11.
[0110] The input side of the air conditioning controller 40 is
further connected to a control panel (not shown) disposed in the
instrumental panel at the front end part of the vehicle
compartment, and control signals from various air conditioning
switches provided on the control panel are inputted into the air
conditioning controller 40. The various air conditioning switches
of the control panel includes an activation switch of the vehicle
air conditioner 1, a temperature setting switch used for setting a
temperature inside the vehicle compartment, and a mode selecting
switch used for selecting the air conditioning mode from among the
cooling mode, the dehumidifying-heating mode and the heating
mode.
[0111] The air conditioning controller 40 is further connected to a
non-shown battery which outputs a rated voltage of 12V, and the
battery supplies electric power to the air conditioning controller
40. The air conditioning controller 40 is capable of transforming
the supplied electric power, and thereby supplies the transformed
electric power to the various air conditioning components such as
the PTC heater 50.
[0112] The air conditioning controller 40 integrally includes
control portions (hardware and software) which respectively control
operations of the various air conditioning components connected the
output side of the air conditioning controller 40.
[0113] For example, in the present embodiment, the control portions
include a discharge capacity control portion which controls an
operation of the electric motor of the compressor 11, a refrigerant
circuit control portion which controls operations of the open-close
valves 16a, 16b, 16c used as examples of the refrigerant circuit
switching portion, and a heating capacity control portion 40a used
as an example of a heating capacity adjusting portion which adjusts
the air heating capacity of the auxiliary heater (e.g., PTC heater
50) by adjusting an electric energy supplied to the auxiliary
heater. The discharge capacity control portion, the refrigerant
circuit control portion and the heating capacity control portion
40a may be provided separately from the air conditioning controller
40.
[0114] Next, an operation of the vehicle air conditioner 1 of the
present embodiment will be described in reference to FIGS. 4 to 9.
A control process of the operation of the vehicle air conditioner 1
shown in FIG. 4 starts when the activation switch of the vehicle
air conditioner 1 is turned ON. Each control step of flowcharts
shown in drawings constitutes each of a variety of function
execution portions that the air conditioning controller 40
includes.
[0115] At step S1, the air conditioning controller 40 performs
initializations (initializing process) of a flag, a timer, default
positions of the above-described various electrical actuators and
the like, and then performs a control operation of step S2. In the
initializing process of step S1, some of flags and calculation
values stored at termination of the last operation of the vehicle
air conditioner 1 are maintained.
[0116] At step S2, the air conditioning controller 40 reads in
control signals from the control panel, such as a preset
temperature Tset of the vehicle compartment set by the temperature
setting switch and an air conditioning mode selected by the mode
selecting switch. Subsequently, a control operation of step S3 is
performed. At step S3, the air conditioning controller 40 reads in
signals of vehicle environmental conditions used for performing an
air conditioning control. In other words, the air conditioning
controller 40 reads in detection signals from the sensor group 41
for performing the air conditioning control. Then, the air
conditioning controller 40 performs a control operation of step
S4.
[0117] At step S54, the air conditioning controller 40 calculates a
target outlet temperature TAO (target temperature) of air to be
blown into the vehicle compartment from the air outlets, and then
performs a control operation of step S5. Specifically, at step S4,
the target outlet temperature TAO of the present embodiment is
calculated by using the preset temperature Tset, an inside air
temperature Tr of the vehicle compartment detected by the inside
air sensor, an outside air temperature Tam detected by the outside
air sensor, and a solar radiation amount Ts detected by the solar
radiation sensor.
[0118] At step S5, the air conditioning controller 40 determines an
air blowing capacity (air blowing amount) of the blower 32, and
then performs a control operation of step S6. Specifically, at step
S5, the air blowing amount (e.g., a blower motor voltage applied to
the electric motor of the blower 32) of the blower 32 is determined
by using a control map stored in the air conditioning controller 40
based on the target outlet temperature TAO determined at step
S4.
[0119] For example, in the present embodiment, when the target
outlet temperature TAO is determined within an extremely low
temperature range or an extremely high temperature range at step
S4, the blower motor voltage is set to be high voltage around a
highest value so that the air blowing amount of the blower 32 is
controlled to be around a largest air blowing amount. When the
target outlet temperature TAO is increased from the extremely low
temperature range toward a middle temperature range, the blower
motor voltage is reduced so that the air blowing amount of the
blower 32 is reduced in accordance with the increase of the target
outlet temperature TAO.
[0120] When the target outlet temperature TAO is decreased from the
extremely high temperature range toward the middle temperature
range, the blower motor voltage is reduced so that the air blowing
amount of the blower 32 is reduced in accordance with the decrease
of the target outlet temperature TAO. When the TAO is determined to
be within the middle temperature range, the blower motor voltage is
set to be a lowest value so that the air blowing amount of the
blower 32 becomes a smallest amount.
[0121] At step S6, the air conditioning controller 40 determines
the air conditioning mode based on a control signal inputted from
the mode selecting switch of the control panel. When the cooling
mode is selected as the air conditioning mode by the mode selecting
switch, a control process of step S7 is performed. When the
dehumidifying-heating mode is selected as the air conditioning
mode, a control process of step S8 is performed. When the heating
mode is selected as the air conditioning mode, a control process of
step S9 is performed.
[0122] At steps S7 to S9, the control processes corresponding to
each air conditioning mode are performed, and then a control
operation of step S10 is performed. Details of the control
processes of steps S7 to S9 will be described later.
[0123] At step S10, the air conditioning controller 40 determines a
switching condition (air inlet mode) of the inside/outside air
switching device 33, and then performs a control operation of step
S11. At step S10, the air inlet mode is determined based on the
target outlet temperature TAO by using a control map stored in the
air conditioning controller 40. In the present embodiment, an
outside air mode, in which outside air is mainly introduced into
the air conditioning unit 30, is generally determined as the air
inlet mode. However, when the target outlet temperature TAO is
determined to be within the extremely low temperature range or
within the extremely high temperature range, in other words, when
high cooling performance or high heating performance is required,
an inside air mode is selected as the air inlet mode, in which
inside air is mainly introduced into the air conditioning unit
30.
[0124] At step S11, the air conditioning controller 40 determines
the air outlet mode, and then performs a control operation of step
S12. At step S11, the air outlet mode is determined based on the
target outlet temperature TAO by using a control map stored in the
air conditioning controller 40. In the present embodiment, the air
outlet mode is switched in an order: the foot mode.fwdarw.the
bi-level mode.fwdarw.the face mode, in accordance with change of
the target outlet temperature TAO from a high temperature range to
a low temperature range.
[0125] At step S12, the air conditioning controller 40 outputs
control signals and control voltages to the various air
conditioning components, which are connected to the output side of
the air conditioning controller 40 to be controlled, such that
control states determined at steps S6 to S11 are obtained. At step
S13, the air conditioning controller 40 waits for a control period
.tau.. The air conditioning controller 40 determines the elapse of
the control period .tau., and then performs the control operation
of step S2.
[0126] In the control routine shown in FIG. 4, the air conditioning
controller 40 repeats the above-described control operations:
reading detection signals and control signals.fwdarw.determination
of the control states of the various controlled
components.fwdarw.output of control signals and control voltages to
the various controlled components. The control routine is performed
until the operation of the vehicle air conditioner 1 is required to
be stopped by turning the activation switch OFF, for example. Next,
details of the air conditioning modes performed at steps S7 to S9
will be described.
(a) Cooling Mode
[0127] The cooling mode performed at step S7 will be described. In
the cooling mode, the air conditioning controller 40 fully opens
the first expansion valve 13, and makes the second expansion valve
22 to be in a decompression state in which its open degree is
reduced and its decompression effect is exerted. Additionally, the
air conditioning controller 40 closes the first and third
open-close valves 16a, 16c, and opens the second open-close valve
16b.
[0128] Thus, when the air conditioning controller 40 outputs
control signals and control voltages to the various controlled
components at step S12 shown in FIG. 4, the refrigerant circuit of
the heat pump cycle 10 as shown by solid arrows in FIG. 1 is
provided. In this cycle configuration of the cooling mode, the air
conditioning controller 40 determines operation states of the
various air conditioning components connected to the output side of
the air conditioning controller 40 based on the target outlet
temperature TAO determined at step S4 and detection signals
inputted from the sensor group 41.
[0129] For example, a rotation rate Nc of the compressor 11 (i.e.,
control signal outputted to the electric motor of the compressor
11) is determined as follows. First, a target evaporator
temperature TEO of the interior evaporator 23 is determined based
on the target outlet temperature TAO by using a control map stored
in the air conditioning controller 40. The target evaporator
temperature TEO is determined so as to be equal to or higher than a
predetermined temperature (e.g., 1.degree. C.) which is higher than
a frost formation temperature (i.e., 0.degree. C.), in order to
prevent the interior evaporator 23 from frosting.
[0130] And then, the rotation rate Nc is determined based on a
deviation between the target evaporator temperature TEO and a
temperature of air flowing out of the interior evaporator 23
detected by the evaporator temperature sensor, so that the
temperature of air flowing out of the interior evaporator 23
approaches the target evaporator temperature TEO by a feedback
control.
[0131] A control signal outputted to the second expansion valve 22
is determined such that a supercooling degree of refrigerant
flowing into the second expansion valve 22 approaches a
predetermined target supercooling degree. The target supercooling
degree is determined so that the COP approaches approximately a
largest value. A control signal outputted to the servomotor of the
air mix door 34 is determined so that the air mix door 34 closes an
air passage of the interior condenser 12, and so that a total
amount of air flowing out of the interior evaporator 23 flows into
the bypass air passage 35.
[0132] The above-described control routine such as, reading
detection signals and control signals.fwdarw.calculation of the
target outlet temperature TAO.fwdarw.determination of the operation
conditions of the various air conditioning components.fwdarw.output
of control voltages and control signals, is repeated until the air
conditioning mode is switched to the dehumidifying-heating mode or
to the heating mode at step S6 shown in FIG. 4, or until the
vehicle air conditioner 1 is required to be stopped by, for
example, a control signal from the control panel.
[0133] In the cooling mode of the heat pump cycle 10, high-pressure
refrigerant discharged from the discharge port 11c of the
compressor 11 flows into the interior condenser 12. Because the air
mix door 34 closes the air passage of the interior condenser 12,
the high-pressure refrigerant flows through the interior condenser
12 with radiating heat little.
[0134] The high-pressure refrigerant flowing out of the interior
condenser 12 flows through in an order: the first expansion valve
13.fwdarw.the gas-liquid separator 14.fwdarw.the second open-close
valve 16b, and then flows into the exterior heat exchanger 20.
Because the first expansion valve 13 is fully open, the
high-pressure refrigerant flowing out of the interior condenser 12
flows through the first expansion valve 13 with little
decompression. Subsequently, the refrigerant flowing out of the
first expansion valve 13 flows into the gas-liquid separator 14
from the inflow port 14b of the gas-liquid separator 14.
[0135] Here, the refrigerant flowing into the gas-liquid separator
14 is in a gas state because the refrigerant has exchanged heat
little with air in the interior condenser 12. Thus, the gas
refrigerant flows out of the liquid outflow port 14d without
gas-liquid separation in the gas-liquid separator 14. Moreover, the
first open-close valve 16a is closed, so that the gas refrigerant
does not flow out of the gas outflow port 14c.
[0136] The high-pressure gas refrigerant flowing out of the liquid
outflow port 14d flows into the exterior heat exchanger 20 via the
bypass passage 18 without flowing into the fixed throttle 17
because the second open-close valve 16b is open. The high-pressure
refrigerant flowing into the exterior heat exchanger 20 radiates
heat through heat exchange with outside air blown by the blower fan
21, and thereby condenses.
[0137] The refrigerant flowing out of the exterior heat exchanger
20 flows into the second expansion valve 22 which is in the
decompression state, because the third open-close valve 16c is
closed. Then, the refrigerant flowing into the second expansion
valve 22 changes into low-pressure refrigerant through isenthalpic
expansion and decompression. The low-pressure refrigerant having
decompressed in the second expansion valve 22 flows into the
interior evaporator 23 to absorb heat from air blown by the blower
32 and to evaporate. Accordingly, the air to be blown into the
vehicle compartment is cooled.
[0138] The refrigerant flowing out of the interior evaporator 23 is
separated into gas refrigerant and liquid refrigerant in the
accumulator 24. The gas refrigerant is drawn into the compressor 11
from the suction port 11a, and is compressed again by the
lower-stage compression mechanism and then by the higher-stage
compression mechanism. As described above, in the cooling mode,
because the air mix door 34 closes the air passage of the interior
condenser 12, air cooled by the interior evaporator 23 can be blown
into the vehicle compartment with the air kept in a cool state. In
other words, the air cooled by the interior evaporator 23 can be
blown into the vehicle compartment without passing through the
interior condenser 12. Accordingly, cooling of the vehicle
compartment can be performed.
(b) Dehumidifying-Heating Mode
[0139] Details of the dehumidifying-heating mode performed at step
S8 will be described. In the dehumidifying-heating mode, the air
conditioning controller 40 makes the first expansion valve 13 to be
in a fully open state or in the decompression state, and makes the
second expansion valve 22 to be in a fully open state or in the
decompression state. Moreover, the air conditioning controller 40
closes the first and third open-close valves 16a, 16c, and opens
the second open-close valve 16b. Therefore, a refrigerant circuit
of the heat pump cycle 10 shown by the solid arrows in FIG. 1,
which is similar to the refrigerant circuit of the heat pump cycle
10 in the cooling mode, is provided.
[0140] Additionally, the air conditioning controller 40 determines
a control signal that is to be outputted to the servomotor of the
air mix door 34 such that an open degree of the air mix door 34 is
set to be smallest to close the bypass air passage 35. Accordingly,
an entire flow amount of air having passed through the interior
evaporator 23 flows through the interior condenser 12. However, the
open degree of the air mix door 34 may be adjusted based on the
target outlet temperature TAO, even in the dehumidifying-heating
mode.
[0141] The rotation rate Nc of the compressor 11 is determined such
that the higher-pressure side refrigerant pressure Pd between the
discharge port 11c of the compressor 11 and the inlet side of the
first expansion valve 13 in the heat pump cycle 10 approaches the
target pressure TPd by a feedback control or the like. The target
pressure TPd is determined based on the target outlet temperature
TAO by using a control map stored in the air conditioning
controller 40, such that the temperature of air to be blown into
the vehicle compartment becomes the target outlet temperature
TAO.
[0142] In the dehumidifying-heating mode of the present embodiment,
open degrees of the first and second expansion valves 13, 22 are
changed depending on a temperature difference between the preset
temperature Tset and the outside air temperature Tam. Specifically,
the dehumidifying-heating mode includes first to forth
dehumidifying-heating modes, and one of the four
dehumidifying-heating modes is performed in the
dehumidifying-heating mode depending on the target outlet
temperature TAO.
(b)(i) First Dehumidifying-Heating Mode
[0143] A first dehumidifying-heating mode is one example of the
dehumidifying-heating mode. In the first dehumidifying-heating
mode, the first expansion valve 13 is fully open and the second
expansion valve 22 is in a decompression state, so that a cycle
configuration (refrigerant circuit) of the first
dehumidifying-heating mode is similar to that of the cooling mode.
The air mix door 34 is adjusted to fully open the air passage of
the interior condenser 12.
[0144] High-pressure refrigerant discharged from the discharge port
11c of the compressor 11 flows into the interior condenser 12.
Then, the high-pressure refrigerant radiates heat and condenses
through heat exchange with air that has been cooled and
dehumidified by the interior evaporator 23. Accordingly, air to be
blown into the vehicle compartment is heated by the interior
condenser 12. The refrigerant flowing out of the interior condenser
12 flows through in the order: the first expansion valve
13.fwdarw.the gas-liquid separator 14.fwdarw.the second open-close
valve 16b, and then the refrigerant flows into the exterior heat
exchanger 20. The high-pressure refrigerant flowing into the heat
exchanger 20 radiates heat and condenses through heat exchange with
outside air blown by the blower fan 21. A subsequent refrigerant
flow and corresponding state change of the refrigerant are similar
to those of the cooling mode. That is, the other operation states
of the first dehumidifying-heating mode are similar to those of the
cooling mode.
[0145] As described above, in the first dehumidifying-heating mode,
air having been cooled and dehumidified in the interior evaporator
23 can be heated in the interior condenser 12 and can be blown into
the vehicle compartment. Accordingly, dehumidifying and heating of
the vehicle compartment can be performed.
(b)(ii) Second Dehumidifying-Heating Mode
[0146] When the target outlet temperature TAO becomes higher than a
first reference temperature during the operation of the first
dehumidifying-heating mode, a second dehumidifying-heating mode is
performed. The second dehumidifying-heating mode is another example
of the dehumidifying-heating mode. In the second
dehumidifying-heating mode, the first expansion valve 13 is in a
decompression state, and the second expansion valve 22 is in a
decompression state in which the open degree of the second
expansion valve 22 is larger than that in the first
dehumidifying-heating mode.
[0147] Similarly to the first dehumidifying-heating mode,
high-pressure refrigerant discharged from the discharge port 11c of
the compressor 11 flows into the interior condenser 12 and radiates
heat by heat exchange with air having been cooled and dehumidified
in the interior evaporator 23. Accordingly, air to be blown into
the vehicle compartment is heated in the interior condenser 12.
[0148] The high-pressure refrigerant flowing out of the interior
condenser 12 changes into intermediate-pressure refrigerant through
isenthalpic decompression in the first expansion valve 13 which is
in a decompression state. The intermediate-pressure refrigerant
flowing out of the first expansion valve 13 flows through in an
order: the gas-liquid separator 14.fwdarw.the second open-close
valve 16b, and then the refrigerant flows into the exterior heat
exchanger 20. The intermediate-pressure refrigerant flowing into
the exterior heat exchanger 20 radiates heat by heat exchange with
outside air blown by the blower fan 21. A subsequent refrigerant
flow and corresponding state change of the refrigerant are similar
to those of the cooling mode.
[0149] As described above, in the second dehumidifying-heating
mode, air having been cooled and dehumidified in the interior
evaporator 23 can be heated in the interior condenser 12 and can be
blown into the vehicle compartment, similarly to the first
dehumidifying-heating mode. Accordingly, dehumidifying and heating
of the vehicle compartment can be performed.
[0150] Because the first expansion valve 13 is in the decompression
state in the second dehumidifying-heating mode, a temperature of
refrigerant passing through the exterior heat exchanger 20 can be
reduced relative to the case of the first dehumidifying-heating
mode. Thus, a temperature difference between the refrigerant and
outside air in the exterior heat exchanger 20 can be reduced, and a
heat radiation amount of refrigerant in the exterior heat exchanger
20 can be thereby reduced.
[0151] As a result, in the second dehumidifying-heating mode, a
heat radiation amount of refrigerant in the interior condenser 12
can be increased, and the air heating capacity of the interior
condenser 12 can be thereby improved relative to the case of the
first dehumidifying-heating mode.
(b)(iii) Third Dehumidifying-Heating Mode
[0152] When the target outlet temperature TAO becomes higher than a
second reference temperature during the operation of the second
dehumidifying-heating mode, a third dehumidifying-heating mode is
performed. The third dehumidifying-heating mode is another example
of the dehumidifying-heating mode. In the third
dehumidifying-heating mode, the open degree of the first expansion
valve 13 is adjusted to be smaller than that in the second
dehumidifying-heating mode, and the open degree of the second
expansion valve 22 is adjusted to be larger than that in the second
dehumidifying-heating mode.
[0153] Similarly to the first and second dehumidifying-heating
modes, high-pressure refrigerant discharged from the discharge port
11c of the compressor 11 flows into the interior condenser 12 and
radiates heat by heat exchange with air having been cooled and
dehumidified in the interior evaporator 23 in the third
dehumidifying-heating mode. Accordingly, air to be blown into the
vehicle compartment is heated in the interior condenser 12.
[0154] The high-pressure refrigerant flowing out of the interior
condenser 12 changes into intermediate-pressure refrigerant through
isenthalpic decompression of the first expansion valve 13 which is
in the decompression state. The intermediate-pressure refrigerant
flowing out of the first expansion valve 13 flows through in an
order: the gas-liquid separator 14.fwdarw.the second open-close
valve 16b, and then the refrigerant flows into the exterior heat
exchanger 20. Here, the intermediate pressure is set such that the
temperature of the intermediate-pressure refrigerant becomes lower
than the temperature of the outside air.
[0155] The intermediate-pressure refrigerant flowing into the
exterior heat exchanger 20 absorbs heat and evaporates by heat
exchange with outside air blown by the blower fan 21. The
refrigerant flowing out of the exterior heat exchanger 20 is
decompressed by the second expansion valve 22 without change in
enthalpy of the refrigerant, and then flows into the interior
evaporator 23. A subsequent refrigerant flow and corresponding
state change of the refrigerant are similar to those of the cooling
mode.
[0156] As described above, in the third dehumidifying-heating mode,
air having been cooled and dehumidified in the interior evaporator
23 can be heated in the interior condenser 12 and can be blown into
the vehicle compartment, similarly to the first and second
dehumidifying-heating modes. Accordingly, dehumidifying and heating
of the vehicle compartment can be performed.
[0157] Because the exterior heat exchanger 20 is used as an
evaporator by reducing the open degree of the first expansion valve
13 in the third dehumidifying-heating mode, a heat absorption
amount of refrigerant from outside air can be increased. Thus, a
heat radiation amount of refrigerant in the interior condenser 12
can be increased, and the air heating capacity of the interior
condenser 12 can be thereby improved relative to the second
dehumidifying-heating mode.
(b)(iv) Fourth Dehumidifying-Heating Mode
[0158] When the target outlet temperature TAO becomes higher than a
third reference temperature during the operation of the third
dehumidifying-heating mode, a fourth dehumidifying-heating mode is
performed. The fourth dehumidifying-heating mode is another example
of the dehumidifying-heating mode. In the fourth
dehumidifying-heating mode, the open degree of the first expansion
valve 13 is adjusted to be smaller than in the third
dehumidifying-heating mode, and the open degree of the second
expansion valve 22 is fully open.
[0159] Similarly to the first to third dehumidifying-heating modes,
high-pressure refrigerant discharged from the discharge port 11c of
the compressor 11 flows into the interior condenser 12 and radiates
heat by heat exchange with air having been cooled and dehumidified
in the interior evaporator 23. Accordingly, air to be blown into
the vehicle compartment is heated in the interior condenser 12.
[0160] The refrigerant flowing out of the interior condenser 12
changes into low-pressure refrigerant having a temperature lower
than an outside air temperature through isenthalpic decompression
in the first expansion valve 13 which is in the decompression
state. The low-pressure refrigerant flowing out of the first
expansion valve 13 flows through in the order: the gas-liquid
separator 14.fwdarw.the second open-close valve 16b, and then the
refrigerant flows into the exterior heat exchanger 20.
[0161] The low-pressure refrigerant flowing into the exterior heat
exchanger 20 absorbs heat and evaporates by heat exchange with
outside air blown by the blower fan 21. The refrigerant flowing out
of the exterior heat exchanger 20 flows into the interior
evaporator 23 without decompression because the second expansion
valve 22 is fully open. A subsequent refrigerant flow and
corresponding state change of the refrigerant are similar to those
of the cooling mode.
[0162] As described above, in the fourth dehumidifying-heating
mode, air having been cooled and dehumidified in the interior
evaporator 23 can be heated in the interior condenser 12 and can be
blown into the vehicle compartment, similarly to the first to third
dehumidifying-heating modes. Accordingly, dehumidifying and heating
of the vehicle compartment can be performed.
[0163] In the fourth dehumidifying-heating mode, similarly to the
third dehumidifying-heating mode, the exterior heat exchanger 20 is
used as an evaporator, and the open degree of the first expansion
valve 13 is smaller than in the third dehumidifying-heating mode.
Hence, a refrigerant evaporation temperature in the exterior heat
exchanger 20 can be reduced.
[0164] Therefore, the temperature difference between refrigerant
and outside air in the exterior heat exchanger 20 can be increased,
and the heat absorption amount of refrigerant from outside air can
be increased, relative to the third dehumidifying-heating mode. As
a result, a, heat radiation amount of refrigerant in the interior
condenser 12 can be increased, and the air heating capacity of the
interior condenser 12 can be thereby improved relative to the third
dehumidifying-heating mode.
(c) Heating Mode
[0165] Next, details of the heating mode performed at step S9 will
be described with reference to FIGS. 5 to 9. At step S91 shown in
FIG. 5, the air conditioning controller 40 determines control
states of, for example, the expansion valves 13, 22, the air mix
door 34 and the refrigerant circuit switching portion (16a, 16b,
16c).
[0166] Specifically, the open degree of the first expansion valve
13 is reduced to decompress refrigerant, and the second expansion
valve 22 is fully closed. The control state of the servomotor for
the air mix door 34 is determined such that the air mix door 34 is
actuated to close the bypass air passage 35 as shown in FIG. 2.
Additionally, the first and third open-close valves 16a, 16c are
open, and the second open-close valve 16b is closed.
[0167] Accordingly, at step S12 shown in FIG. 4, when the air
conditioning controller 40 outputs control signals and control
voltages to the controlled components, a refrigerant circuit of the
heat pump cycle 10 shown by solid arrows in FIG. 2 is provided.
[0168] Specifically, the heat pump cycle 10 is switched to a
gas-injection cycle (economizer refrigerant cycle). In this cycle,
refrigerant is compressed in stages by the two compression
mechanisms which are the lower-stage compression mechanism and the
higher-stage compression mechanism of the compressor 11. Moreover,
intermediate-pressure refrigerant in the heat pump cycle 10 is
combined with refrigerant discharged from the lower-stage
compression mechanism, and the combined refrigerant is drawn into
the higher-stage compression mechanism.
[0169] At step S92, the air conditioning controller 40 determines
the target pressure TPd of the higher-pressure side refrigerant
pressure Pd, and then performs a control operation of step S93.
Here, the higher-pressure side refrigerant pressure Pd is a
pressure between the discharge port 11c of the compressor 11 and
the inlet side of the first expansion valve 13. The target pressure
TPd is determined by using a control map stored in the air
conditioning controller 40 based on the target outlet temperature
TAO determined at step S4 shown in FIG. 4, such that the
temperature of air to be blown into the vehicle compartment becomes
the target outlet temperature TAO
[0170] At step S93, the air conditioning controller 40 determines
whether a present rotation rate Nc of the compressor 11 reaches a
largest rotation rate Ncmax predetermined based on durability of
the compressor 11. In other words, the air conditioning controller
40 determines whether the present rotation rate Nc is equal to the
largest rotation rate Ncmax (Nc=Ncmax). When the present rotation
rate Nc is not equal to the largest rotation rate Ncmax at step
S93, the air conditioning controller 40 performs a control process
of step S94 to perform a subcool control. When the present rotation
rate Nc is equal to the largest rotation rate Ncmax (Nc=Ncmax) at
step S93, a control operation of step S95 is performed.
[0171] The subcool control performed at step S94 will be described
referring to the flowchart of FIG. 6. The subcool control is
performed when the present rotation rate Nc is not equal to the
largest rotation rate Ncmax at step S93. In other words, the
subcool control is performed when the refrigerant discharge
capacity of the compressor 11 can be increased more than a present
refrigerant discharge capacity of the compressor 11.
[0172] At step S941 shown in FIG. 6, the air conditioning
controller 40 determines a target supercooling degree TSC of
refrigerant flowing out of the interior condenser 12, and then
performs a control operation of step S942. Specifically, at step
S941, the target supercooling degree TSC is determined based on a
temperature and a pressure of the refrigerant flowing out of the
interior condenser 12 such that the COP of the heat pump cycle 10
becomes largest.
[0173] At step S942, the air conditioning controller 40 determines
whether the target supercooling degree TSC is higher than a present
supercooling degree SC of the refrigerant flowing out of the
interior condenser 12. Here, the present supercooling degree SC is
calculated based, on a temperature and a pressure of the
refrigerant flowing out of the interior condenser 12. When the
present supercooling degree SC is lower than the target
supercooling degree TSC at step S942, a control operation of step
S944 is performed. When the present supercooling degree SC is not
lower than the target supercooling degree TSC at step S942, a
control operation of step S943 is performed.
[0174] Here, the supercooling degree SC of the present embodiment
is defined as an absolute value of a difference between a present
temperature of refrigerant in a liquid state and a saturation
temperature of the refrigerant at a constant pressure. Hence, a
temperature of liquid refrigerant decreases in accordance with
increase of the supercooling degree SC. At step S943, the open
degree of the first expansion valve 13 is increased by a
predetermined degree from a present open degree of the first
expansion valve 13, and then a control process of step S98 is
performed. The increase of the open degree of the first expansion
valve 13 causes a pressure of high-pressure side refrigerant to
reduce, so that the supercooling degree SC of refrigerant flowing
out of the interior condenser 12 reduces to approach the target
supercooling degree TSC.
[0175] At step S944, the air conditioning controller 40 determines
whether a present open degree of the first expansion valve 13 is
larger than a smallest open degree of the first expansion valve 13.
When the present open degree of the first expansion valve 13 is
larger than the smallest open degree of the first expansion valve
13 at step S944, a control operation of step S945 is performed. At
step S945, the open degree of the first expansion valve 13 is
decreased by a predetermined degree from the present open degree of
the first expansion valve 13, and then the control process of step
S98 is performed. The decrease of the open degree of the first
expansion valve 13 causes the pressure of high-pressure side
refrigerant to increase, so that the supercooling degree SC of
refrigerant flowing out of the interior condenser 12 increases to
approach the target supercooling degree TSC.
[0176] When the present open degree of the first expansion valve 13
is not larger than the smallest open degree at step S944, i.e.,
when the present open degree of the first expansion valve 13 is
equal to the smallest open degree at step S944, the present open
degree of the first expansion valve 13 cannot be decreased.
Therefore, the present open degree is kept, and the control process
of step S98 is performed.
[0177] The subcool control is performed at step S94 when the
refrigerant discharge capacity of the compressor 11 can be
increased more than a present refrigerant discharge capacity
thereof, and the open degree of the first expansion valve 13 is
adjusted so that the supercooling degree SC approaches the target
supercooling degree TSC. Accordingly, the COP approaches a largest
value.
[0178] Next, at step S95 shown in FIG. 5, the air conditioning
controller 40 determines whether a present open degree of the first
expansion valve 13 is smaller than a largest open degree thereof.
In other words, the air conditioning controller 40 determines
whether the first expansion valve 13 is in the fully open state.
When the present open degree of the first expansion valve 13 is
smaller than the largest open degree at step S95, the air
conditioning controller 40 performs a control process of step S96
to perform a quality control (dryness control). When the present
open degree of the first expansion valve 13 is not smaller than the
largest open degree at step S95, the air conditioning controller 40
performs a control process of step S97 to perform a PTC-heater
control.
[0179] The quality control performed at step S96 will be described
with reference to the flowchart of FIG. 7. The quality control is
performed when refrigerant flowing out of the interior condenser 12
can be made to be in a gas-liquid two-phase state by increasing the
present open degree of the first expansion valve 13. For example,
the quality control is performed when the heating capacity of the
interior condenser 12 is insufficient during the subcool
control.
[0180] At step S961, the air conditioning controller 40 determines
whether a present higher-pressure side refrigerant pressure Pd is
smaller than the target pressure TPd determined at step S92. When
the present higher-pressure side refrigerant pressure Pd is smaller
than the target pressure TPd at step S961, the air conditioning
controller 40 performs a control operation, of step S962. When the
present higher-pressure side refrigerant pressure Pd is not smaller
than the target pressure TPd at step S961, in other words, when the
present higher-pressure side refrigerant pressure Pd is equal to or
larger than the target pressure TPd, the air conditioning
controller 40 performs a control operation of step S964.
[0181] At step S962, the air conditioning controller 40 determines
whether a present open degree of the first expansion valve 13 is
smaller than the largest open degree thereof. In other words, the
air conditioning controller 40 determines whether the first
expansion valve 13 is in the fully open state. When the present
open degree of the first expansion valve 13 is smaller than the
largest open degree at step S962, the air conditioning controller
40 performs a control operation of step S963. At step S963, the
present open degree of the first expansion valve 13 is increased by
a predetermined degree. Subsequently, the control process of step
S98 is performed.
[0182] When the present open degree of the first expansion valve 13
is not smaller than the largest open degree at step S962, in other
words, when the first expansion valve 13 is in the fully open
state, the present open degree of the first expansion valve 13
cannot be increased. Thus, the present open degree is kept, and the
control process of step S98 is performed.
[0183] At step S964, the air conditioning controller 40 determines
whether a present open degree of the first expansion valve 13 is
larger than the smallest open degree of the first expansion valve
13. When the present open degree of the first expansion valve 13 is
larger than the smallest open degree at step S964, the air
conditioning controller 40 performs a control operation of step
S965. At step S965, the present open degree of the first expansion
valve 13 is increased by a predetermined degree. Then, the air
conditioning controller 40 performs the control process of step
S98.
[0184] When the present open degree of the first expansion valve 13
is not larger than the smallest open degree at step S964, in other
words, when the present open degree of the first expansion valve 13
is in a fully closed state, the present open degree of the first
expansion valve 13 cannot be reduced. Hence, the present open
degree is kept, and the control process of step S98 is
performed.
[0185] The quality control is performed at step S96 when the
refrigerant discharge capacity of the compressor 11 cannot be
increased more than the present refrigerant discharge capacity
thereof, and the open degree of the first expansion valve 13 is
increased to increase a flow amount (gas injection amount) of
refrigerant flowing into the compressor 11 via the intermediate
pressure port 11b. Accordingly, a compression work amount of the
compressor 11 is increased, and a quality (dryness) of refrigerant
flowing out of the interior condenser 12 is increased. As a result,
air to be blown into the vehicle compartment is heated to the
target outlet temperature TAO.
[0186] Next, the PTC-heater control (control of the air heating
capacity of the PTC heater 50) performed at step S97 shown in FIG.
5 will be described with reference to the flowchart of FIG. 8. The
PTC-heater control is performed when the air heating capacity of
the interior condenser 12 cannot be increased by a heating capacity
control of the interior condenser 12, such as the subcool control
and the quality control, which is performed for increasing the air
heating capacity of the interior condenser 12. Specifically, when
the rotation rate Nc of the compressor 11 is equal to the largest
rotation rate Ncmax, and when the open degree of the first
expansion valve 13 is equal to the largest open degree, air to be
blown into the vehicle compartment cannot be heated to the target
outlet temperature TAO by the control of the rotation rate Nc of
the compressor 11 and the control of the open degree of the first
expansion valve 13. In this case, the PTC-heater control shown in
FIG. 8 is performed.
[0187] At step S971, the air conditioning controller 40 determines
whether a present higher-pressure side refrigerant pressure Pd is
higher than the target pressure TPd determined at step S92. When
the present higher-pressure side refrigerant pressure Pd is higher
than the target pressure TPd at step S971, the air conditioning
controller 40 performs a control operation of step S972. When the
present higher-pressure side refrigerant pressure Pd is not higher
than the target pressure TPd at step S971, the air conditioning
controller 40 performs a control operation of step S975.
[0188] When the present higher-pressure side refrigerant pressure
Pd is higher than the target pressure TPd at step S971, the blown
air can be heated to the target temperature TAO only by the air
heating capacity of the interior condenser 12. Thus, the air
conditioning controller 40 determines the operation mode of the PTC
heater 50 at step S972, and then reduces the air heating capacity
of the PTC heater 50.
[0189] Specifically, when the operation mode of the PTC heater 50
is determined to be the above-described HIGH mode at step S972, the
air conditioning controller 40 (heating capacity control portion
40a) switches the operation mode to the above-described LOW mode at
step S973, and then performs the control process of step S98. When
the operation mode of the PTC heater 50 is determined to be the LOW
mode at step S972, the air conditioning controller 40 (heating
capacity control portion 40a) switches the operation mode to the
above-described OFF mode at step S974, and then performs the
control process of step S98.
[0190] Additionally, when the operation mode of the PTC heater 50
is determined to be the OFF mode at step S972, the OFF mode is
kept, and the control process of step S98 is performed.
[0191] At step S971, when the present higher-pressure side
refrigerant pressure Pd is higher than the target pressure TPd, the
blown air cannot be heated to the target outlet temperature TAO
only by the air heating capacity of the interior condenser 12.
Thus, the air conditioning controller 40 determines the operation
mode of the PTC heater 50 at step S975, and then increases the air
heating capacity of the PTC heater 50.
[0192] Specifically, when the operation mode of the PTC heater 50
is determined to be the HIGH mode at step S975, the HIGH mode is
kept, and the control process of step S98 is performed. When the
operation mode of the PTC heater 50 is determined to be the LOW
mode at step S975, the air conditioning controller 40 (heating
capacity control portion 40a) switches the operation mode to the
HIGH mode at step S976, and then performs the control process of
step S98. Additionally, when the operation mode of the PTC heater
50 is determined to be the OFF mode at step S975, the air
conditioning controller 40 (heating capacity control portion 40a)
switches the operation mode to the LOW mode at step S977, and then
performs the control process of step S98.
[0193] At step S98 shown in FIG. 5, the rotation rate Nc of the
compressor 11 is determined by the feedback control so that the
higher-pressure side refrigerant pressure Pd approaches the target
pressure TPd. The determination of the rotation rate Nc of the
compressor 11 at step S98 will be described referring to the
flowchart of FIG. 9. At step S981, the air conditioning controller
40 determines whether a present higher-pressure side refrigerant
pressure Pd is lower than the target pressure TPd determined at
step S92.
[0194] When the present higher-pressure side refrigerant pressure
Pd is determined to be lower than the target pressure TPd at step
S981, a control operation of step S982 is performed. At step S982,
the air conditioning controller 40 determines whether a present
rotation rate Nc of the compressor 11 is lower than the largest
rotation rate Ncmax. When the present rotation rate Nc of the
compressor 11 is determined to be lower than the largest rotation
rate Ncmax at step S982, a control operation of step S983 is
performed. The air conditioning controller 40 increases the
rotation rate Nc of the compressor 11 by a predetermined degree at
step S983, and then performs the control operation of step S10
shown in FIG. 4.
[0195] When the present rotation rate Nc of the compressor 11 is
determined not to be lower than the largest rotation rate Ncmax at
step S982, in other words, when the present rotation rate Nc of the
compressor 11 is equal to the largest rotation rate Ncmax, the
present rotation rate Nc of the compressor 11 cannot be increased.
Hence, the present rotation rate Nc is kept, and the control
operation of step S10 shown in FIG. 4 is performed.
[0196] When the present higher-pressure side refrigerant pressure
Pd is determined not to be lower than the target pressure TPd at
step S981, a control operation of step S984 is performed. At step
S984, the air conditioning controller 40 decreases the rotation
rate Nc of the compressor 11 by a predetermined degree, and then
performs the control operation of the step S10 shown in FIG. 4.
[0197] In the heating mode, because the control process is
performed as described above, a state of refrigerant in the heat
pump cycle 10 is changed as shown by the Mollier diagram of FIG.
10. In FIG. 10, a state change of refrigerant in the subcool
control is shown by a bold solid line, and a state change of
refrigerant in the quality control is shown by a bold dash line.
Furthermore, a state change of refrigerant in the PTC-heater
control is shown by a bold alternate long and short dash line in
FIG. 10.
[0198] When the subcool control is performed in the heating mode as
shown in the control process of step S94 in FIG. 6, high-pressure
refrigerant flowing out of the discharge port 11c of the compressor
11, which is shown by the point a in FIG. 10, flows into the
interior condenser 12. The refrigerant flowing into the interior
condenser 12 radiates heat and condenses through heat exchange with
air having passed through the interior evaporator 23, as shown by
the point a.fwdarw.the point b in FIG. 10. Accordingly, the air to
be blown into the vehicle compartment is heated.
[0199] The refrigerant flowing out of the interior condenser 12
flows into the first expansion valve 13 which is in the
decompression state, and changes into intermediate-pressure
refrigerant through isenthalpic expansion and decompression in the
first expansion valve 13 as shown by the point b.fwdarw.the point
c1. Subsequently, the intermediate-pressure refrigerant
decompressed in the first expansion valve 13 is separated into
liquid refrigerant and gas refrigerant in the gas-liquid separator
14 as shown by the point c1.fwdarw.the point c2, and the point
c1.fwdarw.the point c3 in FIG. 10.
[0200] The intermediate-pressure gas refrigerant separated in the
gas-liquid separator 14 flows into the intermediate pressure port
11b of the compressor 11 via the intermediate pressure passage 15
as shown by the point c2.fwdarw.the point a2 in FIG. 10 because the
first open-close valve 16 is open. The refrigerant flowing into the
compressor 11 via the intermediate pressure port 11b is combined
with refrigerant (the point a1 in FIG. 10) discharged from the
lower-stage compression mechanism. The combined refrigerant is
drawn into the higher-stage compression mechanism.
[0201] The intermediate-pressure liquid refrigerant separated in
the gas-liquid separator 14 flows into the fixed throttle 17
because the second open-close valve 16b is closed. The liquid
refrigerant changes into low-pressure refrigerant through
isenthalpic expansion and decompression in the fixed throttle 17 as
shown by the point c3.fwdarw.the point c4 in FIG. 10. The
low-pressure refrigerant flowing out of the fixed throttle 17 flows
into the exterior heat exchanger 20. Then, the low-pressure
refrigerant absorbs heat and evaporates through heat exchange with
outside air blown by the blower fan 21 in the exterior heat
exchanger 20 as shown by the point c4.fwdarw.the point d in FIG.
10.
[0202] The refrigerant flowing out of the exterior heat exchanger
20 flows into the accumulator 24 via the bypass passage 25 because
the third open-close valve 16c is open. The refrigerant is
separated into gas refrigerant and liquid refrigerant in the
accumulator 24, and the separated gas refrigerant is drawn into the
compressor 11 through the suction port 11a, as shown by the point e
in FIG. 10, to be compressed in the compressor 11. The separated
liquid refrigerant is accumulated in the accumulator 24 as surplus
refrigerant which is unnecessary refrigerant to provide a required
refrigeration capacity of the heat pump cycle 10.
[0203] Here, the reason, why the point d and the point e are
different from each other in FIG. 10, is that a pressure loss is
generated in the gas refrigerant passing through a refrigerant pipe
from the accumulator 24 to the suction port 11a of the compressor
11. Ideally, the points d and e are identical with each other. The
reason of the difference is similar to the other air conditioning
modes.
[0204] Thus, in the subcool control of the heating mode, air can be
heated through heat exchange with high-temperature and
high-pressure refrigerant discharged from the compressor 11 in the
interior condenser 12, and can be blown into the vehicle
compartment. Accordingly, the vehicle compartment can be heated.
Moreover, in the subcool control, the super cooling degree SC of
refrigerant flowing out of the interior condenser 12, shown by the
point b in FIG. 10, can be controlled to approach the target super
cooling degree TSC through the adjustment of the open degree of the
first expansion valve 13, and the COP of the heat pump cycle 10 can
thereby approach a largest value.
[0205] In the subcool control, when the rotation rate Nc of the
compressor 11 is equal to the largest rotation rate Ncmax, and when
the air heating capacity of the interior condenser 12 is
insufficient to increase a temperature of air blown to the vehicle
compartment to the target outlet temperature TAO, the subcool
control is switched to the quality control shown by the control
process of step S96 in FIG. 7.
[0206] When the quality control is performed, a state of
refrigerant is changed as shown by the bold dash line in FIG. 10.
In FIG. 10, a state of refrigerant in the quality control is
assigned the same character as a corresponding state in the subcool
control, and the characters in the quality control are
apostrophized.
[0207] In the quality control, because the open degree of the first
expansion valve 13 is increased to increase a quality of
refrigerant flowing out of the interior condenser 12, a state of
refrigerant flowing out of the interior condenser 12 changes into a
state shown by the point b' in FIG. 10. Moreover, a pressure of
refrigerant flowing into the compressor 11 via the intermediate
pressure port 11b and a pressure refrigerant discharged from the
compressor 11 via the discharge port 11c are increased as compared
with the case of the subcool control, as shown by, for example, the
points c2' and a' in FIG. 10.
[0208] Thus, in the quality control, a temperature of refrigerant
discharged from the compressor 11 can be increased, and a
temperature difference between high-pressure refrigerant flowing
through the interior condenser 12 and air flowing into the interior
condenser 12 can be thereby widen as compared with the case of the
subcool control. Additionally, a flow amount (gas injection amount)
of refrigerant flowing into the compressor 11 via the intermediate
pressure port 11b can be increased as compared with the case of the
subcool control. As a result, in the quality control, the air
heating capacity of the interior condenser 12 can be increased as
compared with the case of the subcool control.
[0209] Here, as described above, the air heating capacity of the
interior condenser 12 can be expected to be increased in the
quality control. However, in the quality control, an enthalpy
difference between refrigerant flowing at the refrigerant inlet of
the interior condenser 12 and refrigerant flowing at the
refrigerant outlet of the interior condenser 12 is reduced as
compared with the case of the subcool control, and the air heating
capacity of the interior condenser 12 may be thereby unable to be
increased when the open degree of the first expansion valve 13 is
larger than a certain value.
[0210] In the present embodiment, during the quality control, when
the open degree of the first expansion valve 13 is equal to the
largest open degree, and when air to be blown to the vehicle
compartment cannot be heated to the target outlet temperature TAO
by the air heating capacity of the interior condenser 12, the
quality control is switched to the PTC-heater control shown by the
control process of step S97 in FIG. 8. In other words, when a
temperature of air that is to be blown into the vehicle compartment
is equal to or lower than the target outlet temperature TAO in the
quality control, the PTC-heater control is performed.
[0211] When the PTC-heater control is performed, a state of
refrigerant is changed as shown by the bold alternate long and
short dash line in FIG. 10. In FIG. 10, a state of refrigerant in
the PTC-heater control is assigned the same character as a
corresponding state in the subcool control, and the characters in
the PTC-heater control are double-apostrophized.
[0212] In the PTC-heater control, the air conditioning controller
40 (the heating capacity control portion 40a) increases a voltage
applied to the PTC heater 50 to increase the air heating capacity
of the PTC heater 50. Accordingly, a temperature of air flowing
into the interior condenser 12 is increased, and a heat absorption
amount of the air from the refrigerant in the interior condenser
12, i.e., a heat radiation amount of the refrigerant to the air in
the interior condenser 12 reduces temporarily.
[0213] Thus, in the PTC-heater control, the heat exchange capacity
of the interior condenser 12 decreases substantially, and
refrigerant circulating in the heat pump cycle 10 balances so that
a pressure of refrigerant in the interior condenser 12 increases,
as shown by the point a'' and the point b'' in FIG. 10. Therefore,
a temperature of refrigerant discharged from the compressor 11 can
be increased, and a temperature difference between high-pressure
refrigerant flowing through the interior condenser 12 and air
flowing into the interior condenser 12 can be increased.
[0214] Additionally, a compression work amount in a compression
process in the higher-stage compression mechanism of the compressor
11 can be increased. Here, the compression process in the
higher-stage compression mechanism is a compression process from
the intermediate pressure port 11b to the discharge port 11c and is
shown by the point a2'.fwdarw.the point a'' in FIG. 10. Hence, the
enthalpy difference between refrigerant in the refrigerant inlet of
the interior condenser 12 and refrigerant in the refrigerant outlet
of the interior condenser 12 can be increased as compared with the
case of the quality control, as shown by the difference
.DELTA.ic2'.fwdarw.the difference .DELTA.ic2'' in FIG. 10. As a
result, in the PTC-heater control, the air heating capacity in the
interior condenser 12 can be improved as compared with the case of
the quality control.
[0215] The vehicle air conditioner 1 of the present embodiment, as
described above, can provide cooling, dehumidifying-heating and
heating of the vehicle compartment, and can heat air efficiently
and effectively depending on a required air heating capacity in the
dehumidifying-heating mode and the heating mode.
[0216] In the present embodiment, the PTC heater 50 used as an
example of the auxiliary heater is arranged upstream of the
interior condenser 12 in the air flow direction so as to heat air
before the air is heated by the interior condenser 12. Thus, the
air heating capacity in the interior condenser 12 can be improved
in the PTC-heater control. In this case, power consumption in the
PTC heater 50 can be reduced relative to a configuration in which
the PTC heater 50 heats air having been heated in the interior
condenser 12.
[0217] More specifically, if the PTC heater 50 is arranged to heat
air having been heated in the interior condenser 12, the PTC heater
50 is required to generate a heat of 2kW (standard heating
capacity) when a rated voltage is applied. However, in the present
embodiment, the PTC heater 50 may be configured to generate a heat
of 800W when the rated voltage is applied. Therefore, the power
consumption in the PTC heater 50 can be reduced relatively.
[0218] Furthermore, because a PTC heater having an air heating
capacity lower than the standard heating capacity can be adopted as
the PTC heater 50, the vehicle air conditioner 1 (refrigerant cycle
device) can be reduced in size and in manufacturing cost as a whole
by downsizing the PTC heater 50 and by reducing a diameter of
harness (electric power line) connecting the PTC heater 50 and the
air conditioning controller 40, for example.
[0219] In the present embodiment, as in the description of control
process of step S97 shown in FIG. 8, the heating capacity control
portion 40a adjusts the air heating capacity of the PTC heater 50
in the PTC-heater control so that the higher-pressure side
refrigerant pressure Pd (refrigerant pressure in the interior
condenser 12) becomes equal to the target pressure TPd, and the
target pressure TPd is determined based on the target outlet
temperature TAO. Therefore, air to be blown into the vehicle
compartment can be heated to the target outlet temperature TAO
easily, and unnecessary energy consumption can be limited.
[0220] In the present embodiment, the cycle configuration of the
heat pump cycle 10 is switchable variedly depending on the air
conditioning mode, and specifically can provide the gas injection
cycle at least in the heating mode. When the gas injection cycle is
provided at least in the heating mode of the heat pump cycle 10 of
the present embodiment, the air heating capacity of the interior
condenser 12 in the heating mode of the present embodiment can be
improved reliably.
[0221] This will be described by comparing the vehicle air
conditioner 1 of the present embodiment with a vehicle air
conditioner of a comparative example. The vehicle air conditioner
of the comparative example includes a normal vapor-compressing
refrigerant cycle having a compressor, a radiator corresponding to
the interior condenser 12 of the present embodiment, an expansion
valve, and an evaporator corresponding to the exterior heat
exchanger 20 of the present embodiment. These components of the
refrigerant cycle are connected in a loop shape. The vehicle air
conditioner of the comparative example further includes a PTC
heater arranged upstream of the radiator to heat air that is to
flow into the radiator.
[0222] In FIG. 11, a bold solid line shows a state change of
refrigerant in a case where a supercooling degree of refrigerant
flowing out of the radiator is controlled to approach a target
supercooling degree without supply of electric power to the PTC
heater. A bold dash line shows a state change of refrigerant in a
case where the supercooling degree of refrigerant flowing out of
the radiator is controlled to approach the target supercooling
degree with the supply of electric power to the PTC heater. In FIG.
11, a state of refrigerant is assigned the same character as the
corresponding state of refrigerant in FIG. 10.
[0223] By the supply of electric power to the PTC heater, the
higher-pressure side refrigerant pressure Pd is increased, and a
compression work amount in the compressor can be increased as shown
by the difference .DELTA.ic.fwdarw.the difference Aid in FIG. 11.
However, an enthalpy difference (heat absorption amount of the
exterior heat exchanger 20) between refrigerant at a refrigerant
inlet of the exterior heat exchanger 20 and refrigerant at a
refrigerant outlet of the exterior heat exchanger 20 is reduced as
shown by the difference .DELTA.ie.fwdarw.the difference .DELTA.ie'
in FIG. 11. Consequently, an air heating capacity of the radiator
may decrease in the comparative example.
[0224] In contrast, in the present embodiment, because the gas
injection cycle is provided at least in the heating mode, the air
heating capacity in the interior condenser 12 can be improved
certainly by arranging the auxiliary heater (e.g., PTC heater 50)
such that air is heated by the auxiliary heater before being heated
through heat exchange with high-pressure refrigerant in the
interior condenser 12.
Second Embodiment
[0225] In the above-described first embodiment, the PTC heater 50
is adopted as an example of the auxiliary heater. In a second
embodiment, as shown in FIG. 12, a vehicle air conditioner 1
includes an auxiliary heat exchanger 60 as an example of the
auxiliary heater, instead of the PTC heater 50 of the first
embodiment. The auxiliary heat exchanger 60 heats air by using a
coolant (heat medium) as a heat source. The coolant cools a
non-shown electric motor for vehicle running, and cools a non-shown
inverter which supplies electric power to the vehicle-running
electric motor. Thus, the vehicle-running electric motor and the
inverter are used as examples of an external heat source.
[0226] In FIG. 12, the refrigerant cycle of the heat pump cycle 10
is set in a state for the heating mode. In FIG. 12, a part is
assigned the same numeral as a same or equivalent part of the first
embodiment.
[0227] The auxiliary heat exchanger 60 is arranged in a coolant
circuit 61 through which the coolant circulates to cool the
external heat source such as the vehicle-running electric motor and
the inverter. The auxiliary heat exchanger 60 is a tank-and-tube
type heat exchanger which heats air through heat exchange with the
coolant flowing in the auxiliary heat exchanger 60. The auxiliary
heat exchanger 60 is arranged upstream of the interior condenser 12
to heat air before flowing into the interior condenser 12.
[0228] Moreover, the auxiliary heat exchanger 60 has an air heating
capacity lower than a standard heating capacity, similarly to the
PTC heater 50 of the first embodiment. The standard heating
capacity of the present embodiment is defined as a necessary
heating capacity (largest heating capacity) for heating air to the
target outlet temperature TAO by using both the air heating
capacity of the interior condenser 12 and the air heating capacity
of the auxiliary heat exchanger 60 in a case where the auxiliary
heat exchanger 60 heats air which has been heated in the interior
condenser 12.
[0229] In the present embodiment, the auxiliary heat exchanger 60
includes a heat-exchange core portion in which the coolant
exchanges heat with air, and the heat-exchange core portion has a
heat-exchange area smaller than a necessary heat-exchange area for
providing the auxiliary heat exchanger 60 with the standard heating
capacity. Consequently, the auxiliary heat exchanger 60 has the air
heating capacity lower than the standard heating capacity.
[0230] In the coolant circuit 61, a flow control valve 62 is
provided to adjust a flow amount of the coolant flowing into the
auxiliary heat exchanger 60. The flow control valve 62 is an
electric open-degree control valve which includes a valve body and
an electric actuator being able to actuate the valve body to change
a cross section of a coolant passage of the coolant circuit 61. An
operation of the flow control valve 62 is controlled by a control
signal outputted from the air conditioning controller 40.
[0231] Thus, the air conditioning controller 40 controls the
operation of the flow control valve 62, and a flow amount of the
coolant flowing into the auxiliary heat exchange 60 is thereby
adjusted. Accordingly, the air heating capacity of the auxiliary
heat exchanger 60 is adjusted. Therefore, the flow control valve 62
of the present embodiment is used as an example of the heating
capacity adjusting portion.
[0232] The air conditioning controller 40 of the present embodiment
is capable of switching an operation mode of the flow control valve
62. The operation mode of the flow control valve 62 includes a HIGH
mode, a LOW mode and an OFF mode. In the HIGH mode, the flow
control valve 62 fully opens the coolant passage of the coolant
circuit 61 to set the air heating capacity of the auxiliary heat
exchanger 60 relatively high. In the LOW mode, the flow control
valve 62 moderately opens the coolant passage to set the air
heating capacity of the auxiliary heat exchange 60 relatively low.
In the OFF mode, the flow control valve 62 closes the coolant
passage so that the auxiliary heat exchanger 60 is not provided
with an air heating capacity.
[0233] The operation mode of the flow control valve 62 is switched
at step S97 shown in FIG. 5, similarly to the PTC heater 50 of the
first embodiment. The other configurations and operations of the
vehicle air conditioner 1 of the second embodiment are similar to
that of the vehicle air conditioner 1 of the first embodiment.
[0234] Accordingly, the vehicle air conditioner 1 (refrigerant
cycle device) is capable of improving the air heating capacity in
the interior condenser 12, similarly to the first embodiment. As a
result, an energy amount consumed by the auxiliary heater (60) in
the heating mode can be reduced, and a size and a manufacturing
cost of the vehicle air conditioner 1 can be reduced as a
whole.
Third Embodiment
[0235] In the first embodiment, the air conditioning controller 40
controls an electric power (e.g. electric voltage) supplied to the
PTC heater 50, thereby switching the operation mode of the PTC
heater 50 among the HIGH mode, the LOW mode and the OFF mode. In a
third embodiment, multiple PTC heaters (electric heaters) are
integrated into a single PTC heater 50.
[0236] Specifically, three PTC heaters are integrated into the PTC
heater 50, and the air conditioning controller 40 changes the
number of PTC heaters, which are energized, to control an air
heating capacity of the PTC heater 50.
[0237] In other words, by changing the energized number of PTC
heaters, an electric power amount supplied to the PTC heater 50 is
adjusted. The PTC heater 50 of the present embodiment has an air
heating capacity lower than the standard heating capacity even when
all of the three PTC heaters are energized.
[0238] The energized number of PTC heaters is determined at step
S97 shown in FIG. 13. The control process of step S97 in FIG. 13
corresponds to the control process of step S97 in FIG. 8 described
in the first embodiment. When a present higher-pressure side
refrigerant pressure Pd is determined to be lower than the target
pressure TPd at step S971, a control operation of step S972' is
performed to increase the energized number of PTC heaters. For
example, when the energized number of PTC heaters is three at step
S972' in a case where the total number of the PTC heaters is three,
the energized number of PTC heaters is kept three.
[0239] When the present higher-pressure side refrigerant pressure
Pd is determined not to be lower than the target pressure TPd at
step S971, a control operation of step S975' is performed to
decrease the energized number of PTC heaters. Here, when the
energized number of PTC heaters is zero at step S975', in other
words, when the PTC heater 50 is not energized, the PTC heater 50
is kept in a non-energized state.
[0240] The other configurations and the other operations in the
third embodiment are similar to those of the first embodiment.
Thus, in a vehicle air conditioner (refrigerant cycle device) of
the third embodiment, similar effects to the first embodiment can
be obtained. Furthermore, the air heating capacity of the PTC
heater 50 can be changed in stages (e.g., three stages) by changing
the energized number of PTC heaters, and an energy amount consumed
by the auxiliary heater (PTC heater 50) in the heating mode can be
thereby reduced further.
Fourth Embodiment
[0241] In the above-described first to third embodiments, the heat
pump cycle 10 is a two stage expansion-type gas injection cycle,
and includes the first expansion valve 13 as an example of the
higher-pressure side expansion device, the fixed throttle 17 as an
example of the lower-pressure side expansion device, and the
gas-liquid separator 14. In the first and third embodiments, the
gas-liquid separator 14 separates intermediate-pressure
refrigerant, which has been decompressed by the first expansion
valve 13, into gas refrigerant and liquid refrigerant, and the
separated gas refrigerant flows to the intermediate pressure port
11b. In a fourth embodiment, a heat pump cycle 10 is an inner
heat-exchange gas injection cycle, and does not include the first
expansion valve 13, the fixed throttle 17 and the gas-liquid
separator 14.
[0242] A vehicle air conditioner 1 (refrigerant cycle device) of
the fourth embodiment will be described with reference to FIG. 14.
In the fourth embodiment, the heat pump cycle 10 of the vehicle air
conditioner 1 includes a refrigerant branch portion 70 provided in
a refrigerant passage connected to the refrigerant outlet side of
the interior condenser 12. High-pressure refrigerant flowing out of
the interior condenser 12 passes through the refrigerant passage,
and the refrigerant passage branches into multiple passages in the
refrigerant branch portion 70. In the fourth embodiment, the
refrigerant passage branches into first and second refrigerant
passages 71 and 73 at the refrigerant branch portion 70. The heat
pump cycle 10 further includes a thermostatic expansion valve 72 as
an example of a first expansion device that is provided in the
first refrigerant passage 71 and decompresses high-pressure
refrigerant flowing out of the interior condenser 12 so that the
high-pressure refrigerant changes into intermediate-pressure
refrigerant.
[0243] The heat pump cycle 10 further includes an inner heat
exchanger 74 in which high-pressure refrigerant flowing through the
second refrigerant passage 73 exchanges heat with the
intermediate-pressure refrigerant decompressed by the thermostatic
expansion valve 72. The inner heat exchanger 74 includes a
high-pressure passage portion 74a, through which the high-pressure
refrigerant from the second refrigerant passage 73 flows, and an
intermediate-pressure passage portion 74b, through which the
intermediate-pressure refrigerant decompressed by the thermostatic
expansion valve 72 flows.
[0244] In the inner heat exchanger 74, the high-pressure
refrigerant having a relatively high temperature and flowing in the
high-pressure passage portion 74a heats the intermediate-pressure
refrigerant having a relatively low temperature and flowing in the
intermediate-pressure passage portion 74b. Accordingly, the
intermediate-pressure refrigerant is evaporated to be gas
refrigerant.
[0245] A refrigerant outlet side of the intermediate-pressure
passage portion 74b is connected to the intermediate pressure port
11b of the compressor 11 through an intermediate pressure passage
15. A thermostatic portion 72a of the thermostatic expansion valve
72 is provided in or adjacent to the intermediate pressure passage
15. The thermostatic expansion valve 72 has a valve body that moves
due to a pressure of intermediate-pressure refrigerant passing
through the thermostatic expansion valve 72 and due to a pressure
depending on a temperature of intermediate-pressure refrigerant
detected by the thermostatic portion 72a. Accordingly, an open
degree of the thermostatic expansion valve 72 is automatically
adjusted so that the intermediate-pressure refrigerant flowing out
of the intermediate-pressure passage portion 74b has a
predetermined superheat degree.
[0246] The intermediate-pressure gas refrigerant, which has
evaporated in the intermediate-pressure passage portion 74b of the
inner heat exchanger 74, passes through the intermediate pressure
passage 15, and then flows into the compressor 11 via the
intermediate pressure port 11b.
[0247] A refrigerant outlet side of the high-pressure passage
portion 74a is connected to an inlet side of an electric expansion
valve 75. The electric expansion valve 75 is used as an example of
a second expansion device that decompresses the high-pressure
refrigerant flowing out of the high-pressure passage portion 74a
into low-pressure refrigerant, and an open degree of the electric
expansion valve 75 is adjustable electrically. An outlet side of
the electric expansion valve 75 is connected to the refrigerant
inlet side of the exterior heat exchanger 20. The electric
expansion valve 75 may have a similar configuration to that of the
first expansion valve 13 described in the first embodiment.
[0248] The other configurations of the vehicle air conditioner 1 of
the fourth embodiment are similar to those of the first embodiment.
Thus, in FIG. 14, parts same as or similar to parts of the first
embodiment are assigned the same numerals as the parts of the first
embodiment, and descriptions of the parts are omitted in the fourth
embodiment.
[0249] In FIG. 14, a refrigerant temperature sensor 41a and a
refrigerant pressure sensor 41b of an air conditioning control
sensor group 41 are provided in the refrigerant passage connected
to the refrigerant outlet side of the interior condenser 12. The
refrigerant temperature sensor 41a detects a temperature of
high-pressure refrigerant flowing out of the interior condenser 12,
and the refrigerant pressure sensor 41b detects a pressure of
high-pressure refrigerant flowing out of the interior condenser
12.
[0250] In the fourth embodiment, the air conditioning controller 40
determines a state of high-pressure refrigerant flowing out of the
interior condenser 12 (i.e., a supercooling degree or a quality
(dryness) of the high-pressure refrigerant) based on detection
signals from the sensors 41a and 41b. The open degree of the
electric expansion valve 75 is adjusted depending on the state of
the high-pressure refrigerant.
[0251] In the heating mode of the inner heat-exchange gas injection
cycle of the fourth embodiment, the subcool control or the quality
control (dryness control) shown in FIGS. 5 to 7 is performed by
controlling the open degree of the electric expansion valve 75
until the rotation rate Nc of the compressor 11 becomes equal to
the largest rotation rate Ncmax and until the open degree of the
electric expansion valve 75 becomes largest. When the air
conditioning controller determines that the heating capacity of the
interior condenser 12 is insufficient in the state where the
rotation rate Nc is equal to the largest rotation rate Ncmax and
where the open degree of the electric expansion valve 75 is
largest, the PTC heater 50 is activated. In other words, when the
heating capacity of the interior condenser 12 cannot be increased
by the heating capacity control of the interior condenser 12, such
as the subcool control and the quality control, the PTC heater 50
is activated.
[0252] When the PTC heater 50 is operated in the heating mode, air
that is to be blown into the vehicle compartment is heated firstly
by the PTC heater 50, and is heated subsequently by the interior
condenser 12 in the air conditioning unit 30.
[0253] When the PTC heater 50 is operated in the heating mode, a
temperature of air flowing into the interior condenser 12 is higher
than that in a case where the PTC heater 50 is not in operation.
Hence, refrigerant cycle in the heat pump cycle 10 is balanced so
that a pressure of high-pressure refrigerant discharged from the
compressor 11 and a condensation temperature of the refrigerant
become higher than those in the case where the PTC heater 50 is not
in operation. Because the pressure of the high-pressure refrigerant
is increased, the compression work amount of the compressor 11 is
increased. As a result, the air heating capacity in the interior
condenser 12 can be improved.
[0254] FIG. 15 shows refrigerant states in the heat pump cycle 10
of the fourth embodiment during the heating mode. In FIG. 15, a
solid line shows refrigerant states when the PTC heater 50 is not
operated, and an alternate long and short dash line shows
refrigerant states when the PTC heater 50 is operated.
[0255] Some of reference characters in FIG. 15 are same as those in
FIG. 10. Each of the same reference characters between FIGS. 15 and
10 indicates a state of refrigerant flowing in the same component
of the heat pump cycle 10. Reference characters f and f'' indicate
states of refrigerant flowing in the refrigerant branch portion 70.
A reference character g indicate a state of refrigerant flowing in
an outlet portion of the thermostatic expansion valve 72, i.e., a
state of refrigerant flowing in an inlet portion of the
intermediate-pressure passage portion 74b of the inner heat
exchanger 74.
[0256] Reference characters h and h'' indicate states of
refrigerant flowing in an outlet portion of the high-pressure
passage portion 74a of the inner heat exchanger 74, i.e. states of
refrigerant flowing in an inlet portion of the electric expansion
valve 75. A reference character c indicates a state of refrigerant
flowing in an outlet portion of the electric expansion valve 75,
i.e., a state of refrigerant flowing in an inlet portion of the
exterior heat exchanger 20. An enthalpy increment indicated by a
line between points g and a2 in FIG. 15 and enthalpy decrements
indicated by lines between points f and h and between points f''
and h'' in FIG. 15 are based on inner heat exchange in the inner
heat exchanger 74.
[0257] In the fourth embodiment, similarly to the above-described
embodiments, when the PTC heater 50 is operated, the compression
work amount (.DELTA.ic2'' in FIG. 15) in the higher-stage
compression mechanism of the compressor 11 can be made to be larger
than that (.DELTA.ic2 in FIG. 15) in the case where the PTC heater
50 is not in operation. Consequently, the air heating capacity in
the interior condenser 12 can be improved.
[0258] In the fourth embodiment, an electric heater such as the PTC
heater 50 is used as an example of the auxiliary heater.
Alternatively, the auxiliary heat exchanger 60 described in the
second embodiment and shown in FIG. 12 may be used as an example of
the auxiliary heater in the fourth embodiment.
Fifth Embodiment
[0259] In the first to fourth embodiments, the PTC heater 50 or the
auxiliary heat exchanger 60, which is an example of the auxiliary
heater, is arranged upstream of the interior condenser 12 in the
air flow direction. In a fifth embodiment, a PTC heater 50 that is
an example of the auxiliary heater is arranged in parallel with an
interior condenser 12 in the air flow direction. In other words,
the PTC heater 50 and the interior condenser 12 are arranged in a
direction perpendicular to the air flow direction.
[0260] Specifically, as shown in FIG. 16, a heat exchange portion
of the interior condenser 12, through which high-pressure
refrigerant flows, is separated into multiple heat exchange
portions 12a, 12b and 12c in the direction perpendicular to the air
flow direction. Two PTC heaters 50 are arranged between the heat
exchange portions 12a and 12b and between the heat exchange
portions 12b and 12c respectively. Accordingly, as shown in FIG.
16, the multiple heat exchange portions 12a, 12b and 12c and the
two PTC heaters 50 are arranged in parallel with respect to the air
flow direction in the fifth embodiment.
[0261] Each of the multiple heat exchange portions 12a, 12b and 12c
includes tubes in which high-pressure refrigerant flows, and fins
arranged between the tubes. The multiple heat exchange portions
12a, 12b and 12c and the two PTC heaters 50 are integrated with
each other by arbitrary fixing method or the like in a state where
the two PTC heaters 50 arranged between the multiple heat exchange
portions 12a, 12b and 12c. Therefore, the interior condenser 12 of
the fifth embodiment is integrated with the PTC heaters 50.
[0262] Because the multiple heat exchange portions 12a, 12b and 12c
and the two PTC heaters 50 are arranged in parallel, with respect
to the air flow direction in the interior condenser 12 of the fifth
embodiment, the multiple heat exchange portions 12a, 12b and 12c
and the PTC heaters 50 simultaneously heat air flowing therethrough
when the PTC heaters 50 are operated.
[0263] The interior condenser 12 has the above-described integrated
structure. Additionally, the multiple heat exchange portions 12a,
12b and 12c, through which high-pressure refrigerant flows, and the
two PTC heaters 50 are arranged alternately in the direction
perpendicular to the air flow direction. Therefore, a temperature
of air flowing into the heat exchange portions 12a, 12b and 12c is
increased by heating effects of the PTC heaters 50 so as to be
higher than that in a case where the PTC heaters 50 are not
provided. Accordingly, a pressure of the high-pressure refrigerant
and a condensation temperature of refrigerant can be increased, and
a compression work amount of the compressor 11 can be increased. As
a result, the air heating capacity in the interior condenser 12 can
be improved.
[0264] In the fifth embodiment, an electric heater such as the PTC
heater 50 is used as an example of the auxiliary heater.
Alternatively, the auxiliary heat exchanger 60 described in the
second embodiment and shown in FIG. 12 may be used as an example of
the auxiliary heater in the fifth embodiment. In other words, the
interior condenser 12 may have a heat exchanger configuration, such
that the multiple heat exchange portions 12a, 12b and 12c, through
which high-pressure refrigerant flows, and the auxiliary heat
exchanger 60, through which heat medium for cooling of an exterior
heat source flows, may be arranged alternately and integrated with
each other.
[0265] Although the present disclosure has been fully described in
connection with the preferred embodiments 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.
Thus, the present disclosure is not limited to the above-described
embodiments, and can be modified variedly as follows without
departing from the scope of the present disclosure.
[0266] (1) In the above-described embodiments, the refrigerant
cycle device of the present disclosure is used for the vehicle air
conditioner 1, which is used for an electric vehicle. The
refrigerant cycle device of the present disclosure can be suitably
used for a vehicle, in which waste heat from an internal combustion
engine is insufficient for use as a heat source of air heating. For
example, the refrigerant cycle device of the present disclosure can
be suitably used for a hybrid vehicle in which a driving force for
vehicle running is obtained from the engine and an electric motor
for vehicle running.
[0267] Moreover, the refrigerant cycle device of the present
embodiment may be used for a stationary air conditioner, a cool
temperature storage and a liquid heater, for example. When the
refrigerant cycle device is used for the liquid heater, a
liquid-refrigerant heat exchanger may be adopted as the
above-described using-side heat exchanger, and a liquid pump or a
flow control valve may be adopted as a flow controller which
adjusts a flow amount of liquid flowing into the liquid-refrigerant
heat exchanger.
[0268] (2) In the above-described second embodiment, the
vehicle-running electric motor and the inverter are adopted as the
external heat source, and the coolant (heat medium), which cools
the vehicle-running electric motor and the inverter, is used as the
heat source of the auxiliary heat exchanger 60. However, the
external heat source and the heat medium are not limited to this.
For example, when the refrigerant cycle device of the present
disclosure is used for a vehicle air conditioner of the
above-described hybrid vehicle, the engine of the hybrid vehicle
may be adopted as the external heat source, and an engine coolant
for the hybrid vehicle may used as the heat medium.
[0269] Further, when the refrigerant cycle device of the present
disclosure is used for a stationary device, such as the stationary
air conditioner, the cool temperature storage or the liquid heater,
an engine for a compressor of the stationary device may be adopted
as the external heat source, and other heat source of the
stationary device may be adopted as the external heat source.
[0270] (3) In the above-described first and second embodiments, the
air heating capacity of the auxiliary heater (e.g., the PTC heater
50, the auxiliary, heat exchanger 60) is changed in stages by
switching the operation mode of the auxiliary heater among the HIGH
mode, the LOW mode and the OFF mode. In the above-described third
embodiment, the air heating capacity of the auxiliary heater is
changed in multiple stages. However, the adjustment of the air
heating capacity of the auxiliary heater is not limited to these.
For example, the air heating capacity of the auxiliary heater may
be increased gradually and continuously in accordance with increase
of a value obtained by subtracting the higher-pressure side
refrigerant pressure Pd from the target pressure TPd.
[0271] (4) In the above-described second embodiment, the auxiliary
heat exchanger 60 has the heat-exchange area smaller than the
necessary heat exchange area for providing the auxiliary heat
exchanger 60 with the standard heating capacity, and the auxiliary
heat exchanger 60 thus has the air heating capacity lower than the
standard heating capacity. However, the auxiliary heat exchanger 60
is not limited to this. For example, the number of tubes of the
auxiliary heat exchanger 60 (tank-and-tube type heat exchanger) or
the number of fins for promotion of heat exchange may be reduced,
or an efficiency of heat exchange may be reduced, so that the
auxiliary heat exchanger 60 has the air heating capacity lower than
the standard heating capacity. Moreover, another type of heat
exchanger may be adopted as the auxiliary heat exchanger 60
alternatively.
[0272] (5) In the above-described embodiments, at step S6 in FIG.
4, the air conditioning mode is determined from among the cooling
mode, the dehumidifying-heating mode and the heating mode depending
on a state of the mode selecting switch. However, the determination
of the air conditioning mode is not limited to this. For example,
the cooling mode may be selected when the outside temperature is
lower than the preset temperature, and the heating mode may be
selected when the outside temperature is higher than the preset
temperature.
[0273] (6) In the above-described embodiments, the quality X of
refrigerant flowing into the exterior heat exchanger 20 is set to
be equal to or lower than 0.1 in the heating mode by appropriately
adjusting a flow characteristic of the fixed throttle 17 used as an
example of the lower-pressure side expansion device. However, the
lower-pressure side expansion device is not limited to the fixed
throttle 17.
[0274] For example, a variable throttle mechanism having a similar
structure to the first expansion valve 13 may be adopted as the
lower-pressure side expansion device. In this case, the air
conditioning controller 40 may detect the quality X of refrigerant
flowing into the exterior heat exchanger 20 based on a temperature
and a pressure of the refrigerant flowing into the exterior heat
exchanger 20, and may control an open degree of the variable
throttle mechanism as an example of the lower-pressure side
expansion device so that the detected quality X becomes equal to or
lower than 0.1.
[0275] (7) In the above-described embodiments, the
dehumidifying-heating mode is switched from the first
dehumidifying-heating mode to the fourth dehumidifying-heating mode
in stages in accordance with increase of the target outlet
temperature TAO, but the switching of the dehumidifying-heating
mode is not limited to this. For example, the dehumidifying-heating
mode may be switched from the first dehumidifying-heating mode to
the fourth dehumidifying-heating mode in a continuous manner in
accordance with increase of the target outlet temperature TAO.
[0276] Hence, the open degree of the first expansion valve 13 may
be decreased, and the open degree of the second expansion valve 22
may be increased, in accordance with the increase of the target
outlet temperature TAO. By changing the open degrees of both the
first and second expansion valves 13, 22, a pressure and a
temperature of refrigerant in the exterior heat exchanger 20 can be
adjusted. Therefore, the exterior heat exchanger 20 can be switched
from a state as a radiator to a state as an evaporator
automatically.
[0277] Additional advantages and modifications will readily occur
to those skilled in the art. The disclosure in its broader terms is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *