U.S. patent application number 12/803372 was filed with the patent office on 2010-12-30 for air conditioner for vehicle with heat pump cycle.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Hiroyuki Hayashi, Yoshinori Ichishi, Mitsuyo Oomura, Takuya Tanihata.
Application Number | 20100326127 12/803372 |
Document ID | / |
Family ID | 43379267 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100326127 |
Kind Code |
A1 |
Oomura; Mitsuyo ; et
al. |
December 30, 2010 |
Air conditioner for vehicle with heat pump cycle
Abstract
An air conditioner for a vehicle includes a vapor compression
refrigeration cycle configured to have a heat pump cycle for
heating air to be blown into an interior of a vehicle compartment,
and a heating member for heating the air using a coolant of an
internal combustion engine of the vehicle as a heat source. In the
air conditioner, an operation request signal is output by an air
conditioning controller to the internal combustion engine when an
outside air temperature is lower than a predetermined
threshold.
Inventors: |
Oomura; Mitsuyo;
(Hekinan-city, JP) ; Hayashi; Hiroyuki; (Obu-city,
JP) ; Tanihata; Takuya; (Nagoya-city, JP) ;
Ichishi; Yoshinori; (Kariya-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
43379267 |
Appl. No.: |
12/803372 |
Filed: |
June 25, 2010 |
Current U.S.
Class: |
62/498 |
Current CPC
Class: |
B60H 2001/3292 20130101;
B60H 2001/00128 20130101; F25B 41/20 20210101; F25B 47/02 20130101;
F25B 6/04 20130101; B60H 1/00785 20130101; B60H 2001/3273 20130101;
B60H 1/3208 20130101; B60H 1/00921 20130101 |
Class at
Publication: |
62/498 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2009 |
JP |
2009-152095 |
Claims
1. An air conditioner for a vehicle, comprising: a vapor
compression refrigeration cycle configured to have a heat pump
cycle for heating air to be blown into an interior of a vehicle
compartment; heating means for heating the air using a coolant of
an internal combustion engine of the vehicle as a heat source; and
control means for outputting an operation request signal to the
internal combustion engine when an outside air temperature is lower
than a predetermined threshold.
2. The air conditioner for a vehicle according to claim 1, further
comprising an electric heater for heating the air by being supplied
with power, wherein, when the outside air temperature is lower than
the predetermined threshold, the control means outputs another
operation request signal to the electric heater, in addition to the
internal combustion engine.
3. The air conditioner for a vehicle according to claim 1, further
comprising determining means for determining whether a possibility
of fogging of a windowpane of the vehicle is high or low, wherein
when the possibility of fogging of the windowpane is high, the
control means sets a required number of revolutions of the internal
combustion engine to be higher than that when the possibility of
fogging of the windowpane is low.
4. The air conditioner for a vehicle according to claim 1, further
comprising a vehicle-interior temperature setting switch for
setting a temperature of an interior of the vehicle compartment by
a passenger's operation, wherein, when a preset temperature set by
the vehicle-interior temperature setting switch is higher than a
predetermined set temperature, the control means sets a required
number of revolutions of the internal combustion engine to be
higher than that when the preset temperature is lower than the
predetermined set temperature.
5. The air conditioner for a vehicle according to claim 1, wherein
the vapor compression refrigeration cycle is configured to be
switched to the heat pump cycle, and to a cooler cycle for cooling
the air to be blown into the interior of the vehicle compartment,
and wherein, when the outside air temperature is lower than the
predetermined threshold, the control means outputs the operation
request signal to the internal combustion engine, and outputs a
control signal for switching to the cooler cycle, to the vapor
compression refrigeration cycle.
6. The air conditioner for a vehicle according to claim 1, wherein,
when the outside air temperature is lower than the predetermined
threshold, the control means outputs the operation request signal
to the internal combustion engine, and outputs another operation
request signal of the heat pump cycle, to the vapor compression
refrigeration cycle.
7. An air conditioner for a vehicle, comprising: a vapor
compression refrigeration cycle including an outdoor heat exchanger
for exchanging heat between refrigerant and outside air, and being
configured to have a heat pump cycle for heating air to be blown
into an interior of a vehicle compartment; heating means for
heating the air using a coolant of an internal combustion engine as
a heat source; a vehicle-interior temperature setting switch for
setting a temperature of the interior of the vehicle compartment by
a passenger's operation; and control means for outputting an
operation request signal to the internal combustion engine when a
preset temperature set by the vehicle-interior temperature setting
switch is higher than a predetermined set temperature.
8. An air conditioner for a vehicle, comprising: a vapor
compression refrigeration cycle including an outdoor heat exchanger
for exchanging heat between refrigerant and outside air, and being
configured to have a heat pump cycle for heating air to be blown
into an interior of a vehicle compartment; heating means for
heating the air using a coolant of an internal combustion engine as
a heat source; and control means for determining whether or not an
operation request signal is output to each of the vapor compression
refrigeration cycle and the internal combustion engine, wherein
when an outside air temperature is lower than a first predetermined
temperature, the control means outputs the operation request signal
to the internal combustion engine without outputting an operation
request signal of the heat pump cycle to the vapor compression
refrigeration cycle, when the outside air temperature is higher
than the first predetermined temperature and lower than a second
predetermined temperature that is higher than the first
predetermined temperature, the control means outputs the operation
request signal of the heat pump cycle to the vapor compression
refrigeration cycle, and also outputs the operation request signal
to the internal combustion engine, and when the outside air
temperature is higher than the second predetermined temperature,
the control means outputs the operation request signal of the heat
pump cycle to the vapor compression refrigeration cycle without
outputting the operation request signal to the internal combustion
engine.
9. The air conditioner for a vehicle according to claim 8, wherein,
in a case where both of a heating by the heat pump cycle and a
heating by the heating means are performed, the control means stops
the heat pump cycle when a temperature of the coolant increases to
more than a predetermined temperature.
10. The air conditioner for a vehicle according to claim 8, wherein
the vapor compression refrigeration cycle is configured to be
switched to the heat pump cycle, and to a cooler cycle for cooling
and dehumidifying the air to be blown into the interior of the
vehicle compartment, and when a temperature of the coolant of the
internal combustion engine increases to more than a predetermined
temperature, the control means outputs an operation request signal
of the cooler cycle to the vapor compression refrigeration
cycle.
11. The air conditioner for a vehicle according to claim 1,
wherein, when the temperature of the coolant is lower than a
predetermined reference value in heating by the heating means, the
control means sets a required number of revolutions of the internal
combustion engine higher than that when the coolant temperature is
higher than the predetermined reference.
12. An air conditioner for a vehicle, comprising: a vapor
compression refrigeration cycle including a compressor for
compressing and discharging a refrigerant, the vapor compression
refrigeration cycle being configured to be switched to a cooler
cycle for cooling air to be blown into an interior of a vehicle
compartment, and to a heat pump cycle for heating the air to be
blown into the interior of the vehicle compartment; and control
means adapted to stop the compressor when a pressure of the
refrigerant is lower than a predetermined pressure, wherein the
control means set the predetermined pressure smaller in the heat
pump cycle, as compared to in the cooler cycle.
13. The air conditioner for a vehicle according to claim 2, wherein
the control means determines a target coolant temperature based on
a target air temperature to be blown into the vehicle compartment,
and decreases and corrects the target coolant temperature when the
electric heater is operated.
14. The air conditioner for a vehicle according to claim 2, wherein
the control means determines a target coolant temperature based on
a target air temperature to be blown into the vehicle compartment,
and decreases and corrects the target coolant temperature based on
power consumption of the electric heater, and the control means
causes a correction amount for decreasing the target coolant
temperature to be increased as the power consumption of the
electric heater becomes larger.
15. The air conditioner for a vehicle according to claim 1, further
comprising a seat heater disposed at a seat for generating heat by
being supplied with power, wherein, when the outside air
temperature is lower than the predetermined threshold, the control
means outputs an operation request signal to the seat heater in
addition to the internal combustion engine.
16. The air conditioner for a vehicle according to claim 15,
wherein the control means determines a target coolant temperature
based on a target air temperature to be blown into the vehicle
compartment, and decreases and corrects the target coolant
temperature when the seat heater is operated.
17. The air conditioner for a vehicle according to claim 15,
wherein the control means determines a target coolant temperature
based on a target air temperature to be blown into the vehicle
compartment, and decreases and corrects the target coolant
temperature based on power consumption of the seat heater, and the
control means causes a correction amount for decreasing the target
coolant temperature to be increased as the power consumption of the
seat heater becomes large.
18. An air conditioner for a vehicle, comprising: heating means for
heating air to be blown into an interior of a vehicle compartment
using a coolant of an internal combustion engine as a heat source;
an electric heater for heating the air by being supplied with
power; and control means for determining a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment, wherein the control means decreases and
corrects the target coolant temperature when the electric heater is
operated.
19. An air conditioner for a vehicle, comprising: heating means for
heating air to be blown into an interior of a vehicle compartment
using a coolant of an internal combustion engine as a heat source;
an electric heater for heating the air by being supplied with
power; and control means for determining a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment, and for decreasing and correcting the target
coolant temperature based on power consumption of the electric
heater, wherein the control means increases a correction amount for
decreasing the target coolant temperature, as the power consumption
of the electric heater becomes larger.
20. An air conditioner for a vehicle, comprising: heating means for
heating air to be blown into an interior of a vehicle compartment
by using a coolant of an internal combustion engine as a heat
source; a seat heater disposed at a seat for generating heat by
being supplied with power; and control means for determining a
target coolant temperature based on a target air temperature to be
blown into the vehicle compartment, wherein the control means
decreases and corrects the target coolant temperature when the seat
heater is operated.
21. An air conditioner for a vehicle, comprising: heating means for
heating air to be blown into an interior of a vehicle compartment
using a coolant of an internal combustion engine as a heat source;
a seat heater disposed at a seat for generating heat by being
supplied with power; and control means for determining a target
coolant temperature based on a target air temperature to be blown
into the vehicle compartment, and for decreasing and correcting the
target coolant temperature based on power consumption of the seat
heater, wherein, as the power consumption of the seat heater
becomes larger, the control means increases a correction amount for
decreasing the target coolant temperature.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2009-152095 filed on Jun. 26, 2009, the contents of which are
incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to an air conditioner for a
vehicle, which is provided with a heat pump cycle.
BACKGROUND OF THE INVENTION
[0003] Conventionally, JP-A-10-100652 discloses regarding an air
conditioner for a vehicle, which includes a heat-pump heating
system for performing a heating operation by use of a heat pump,
and a heater system for performing a heating operation by using hot
water or heat from a heating element.
[0004] JP-A-10-100652 takes into consideration the fact that a
heating efficiency of the heat-pump heating system becomes
deteriorated under an atmosphere where the temperature of outside
air is extremely low. Thus, at the extremely-low outside air
temperature, the heating is performed by the heater system, while
stopping the heat-pump heating system.
[0005] Generally, heater systems using hot water or heat from a
heating element include a device for heating hot water using a
combustion heater, and a PTC heater using a PTC element as a
heating element.
[0006] The technique disclosed in JP-A-10-100652, however, has
various problems in practical use. For example, the heater system
using the combustion heater makes it difficult to sufficiently
clean exhaust gas from the combustion heater, and thus cannot
achieve reduction in emission. That is, provision of an exhaust
emission control system or the like dedicated to the combustion
heater is proposed for sufficiently cleaning the exhaust gas from
the combustion heater, but is difficult to perform within the
limited cost and space for mounting.
[0007] For example, the heater system using the PTC heater is
difficult to ensure adequate heating capacity within the
constraints of cost and mounting space.
[0008] From this point, in vehicles equipped with an engine for
drive (e.g., internal combustion engine), the use of an engine
coolant as a heat source for heating can achieve reduction in
emission. That is, because the exhaust gas from the engine can be
sufficiently cleaned by the existing exhaust emission control
system, it can achieve the reduction in emission without increasing
cost or space for mounting.
[0009] In a vehicle for achieving fuel consumption saving by
stopping an engine, for example, in a hybrid car, an engine coolant
is often at a low temperature, and thus the use of the engine
coolant as a heat source for heating cannot ensure adequate heating
capacity.
SUMMARY OF THE INVENTION
[0010] In view of the foregoing problems, it is an object of the
present invention to improve the practical utility of an air
conditioner for a vehicle, including a heat pump cycle.
[0011] It is another object of the present invention to obtain both
of reduction in emission and adequate heating capacity.
[0012] It is another object of the present invention to provide an
air conditioner for a vehicle, in which heating for a vehicle
compartment is continuously performed even when the heating is
switched from the heating by a heat pump cycle to the heating by
using coolant of an internal combustion engine.
[0013] It is another object of the present invention to provide an
air conditioner for a vehicle, in which an operable range of a heat
pump cycle can be expanded to a low outside air temperature side,
and a refrigerant shortage can be accurately detected in a cooler
cycle.
[0014] It is another object of the present invention to provide an
air conditioner for a vehicle, which can prevent heating capacity
from being excessive, thereby effectively reducing fuel
consumption.
[0015] It is another object of the present invention to provide an
air conditioner for a vehicle, which can prevent warm feeling of a
passenger from being excessive while fuel consumption can be
improved, even when the seat heater is operated.
[0016] According to an aspect of the present invention, an air
conditioner for a vehicle includes a vapor compression
refrigeration cycle configured to have a heat pump cycle for
heating air to be blown into an interior of a vehicle compartment,
heating means for heating the air using a coolant of an internal
combustion engine of the vehicle as a heat source, and control
means for outputting an operation request signal to the internal
combustion engine when an outside air temperature is lower than a
predetermined threshold.
[0017] Accordingly, when the temperature of outside air is lower
than a predetermined threshold, the operation request signal is
output to the internal combustion engine, so that the heating can
be performed by the heating means using the coolant of the engine
as a heat source.
[0018] Thus, reduction in emission can be achieved as compared to
the case of using a combustion heater. That is, since the exhaust
gas from the internal combustion engine can be sufficiently,
cleaned by the existing exhaust emission control system for the
internal combustion engine, the air conditioner according to the
invention can achieve reduction in emission without increasing cost
and space for mounting.
[0019] The air conditioner according to the invention can obtain
the high heating capacity as compared to the case of heating using
only an electric heater, such as the PTC heater, or the case of
heating by the heating means while stopping the internal combustion
engine. Thus, it is possible to achieve reduction in emission and
ensure the heating capacity.
[0020] For example, the air conditioner may further include an
electric heater for heating the air by being supplied with power.
In this case, when the outside air temperature is lower than the
predetermined threshold, the control means outputs another
operation request signal to the electric heater, in addition to the
internal combustion engine.
[0021] Alternatively/Further, the air conditioner may further
include determining means for determining whether a possibility of
fogging of a windowpane of the vehicle is high or low. In this
case, when the possibility of fogging of the windowpane is high,
the control means sets a required number of revolutions of the
internal combustion engine to be higher than that when the
possibility of fogging of the windowpane is low.
[0022] Alternatively/Further, the air conditioner may further
include a vehicle-interior temperature setting switch for setting a
temperature of an interior of the vehicle compartment by a
passenger's operation. In this case, when a preset temperature set
by the vehicle-interior temperature setting switch is higher than a
predetermined set temperature, the control means sets a required
number of revolutions of the internal combustion engine to be
higher than that when the preset temperature is lower than the
predetermined set temperature.
[0023] Alternatively/Further, the vapor compression refrigeration
cycle may be configured to be switched to the heat pump cycle, and
to a cooler cycle for cooling the air to be blown into the interior
of the vehicle compartment. In this case, when the outside air
temperature is lower than the predetermined threshold, the control
means outputs the operation request signal to the internal
combustion engine, and outputs a control signal for switching to
the cooler cycle, to the vapor compression refrigeration cycle.
[0024] Alternatively/Further, when the outside air temperature is
lower than the predetermined threshold, the control means may
output the operation request signal to the internal combustion
engine, and may output another operation request signal of the heat
pump cycle, to the vapor compression refrigeration cycle.
[0025] According to another aspect of the present invention, an air
conditioner for a vehicle includes: a vapor compression
refrigeration cycle including an outdoor heat exchanger for
exchanging heat between refrigerant and outside air, and being
configured to have a heat pump cycle for heating air to be blown
into an interior of a vehicle compartment; heating means for
heating the air using a coolant of an internal combustion engine as
a heat source; a vehicle-interior temperature setting switch for
setting a temperature of the interior of the vehicle compartment by
a passenger's operation; and control means for outputting an
operation request signal to the internal combustion engine when a
preset temperature set by the vehicle-interior temperature setting
switch is higher than a predetermined set temperature.
[0026] When the preset temperature set by the vehicle-interior
temperature setting switch is high, the operating rate of the heat
pump cycle becomes high. Thus, it tends to cause frost formation on
the outdoor heat exchanger, thereby leading to practical problems
such as degraded heat exchange capacity of the outdoor heat
exchanger and reduced heating capacity of the outdoor heat
exchanger.
[0027] With respect to the above problem, when the preset
temperature set by the vehicle interior temperature setting switch
is higher than a predetermined set temperature, the operation
request signal is output to the internal combustion engine, so that
the heating can be carried out by the heating means using the
coolant of the internal combustion engine as a heat source. Thus,
the air conditioner can stably ensure the heating capacity even
when the preset temperature is high, and further improve the
practical utility.
[0028] According to another aspect of the present invention, an air
conditioner for a vehicle includes: a vapor compression
refrigeration cycle including an outdoor heat exchanger for
exchanging heat between refrigerant and outside air, and being
configured to have a heat pump cycle for heating air to be blown
into an interior of a vehicle compartment; heating means for
heating the air using a coolant of an internal combustion engine as
a heat source; and control means for determining whether or not an
operation request signal is output to each of the vapor compression
refrigeration cycle and the internal combustion engine. In the air
conditioner, when an outside air temperature is lower than a first
predetermined temperature, the control means outputs the operation
request signal to the internal combustion engine without outputting
an operation request signal of the heat pump cycle to the vapor
compression refrigeration cycle. In contrast, when the outside air
temperature is higher than the first predetermined temperature and
lower than a second predetermined temperature that is higher than
the first predetermined temperature, the control means outputs the
operation request signal of the heat pump cycle to the vapor
compression refrigeration cycle, and also outputs the operation
request signal to the internal combustion engine. Furthermore, when
the outside air temperature is higher than the second predetermined
temperature, the control means outputs the operation request signal
of the heat pump cycle to the vapor compression refrigeration cycle
without outputting the operation request signal to the internal
combustion engine. Thus, even when the heating is switched from the
heating by the heat pump cycle to the heating by using the coolant
of the internal combustion engine, the heating can be continuously
performed.
[0029] For example, in a case where both of a heating by the heat
pump cycle and a heating by the heating means are performed, the
control means stops the heat pump cycle when a temperature of the
coolant increases to more than a predetermined temperature.
[0030] Furthermore/Alternatively, the vapor compression
refrigeration cycle may be configured to be switched to the heat
pump cycle, and to a cooler cycle for cooling and dehumidifying the
air to be blown into the interior of the vehicle compartment. In
this case, when a temperature of the coolant of the internal
combustion engine increases to more than a predetermined
temperature, the control means may output an operation request
signal of the cooler cycle to the vapor compression refrigeration
cycle.
[0031] In any one air conditioner of the above-described invention,
when the temperature of the coolant is lower than a predetermined
reference value in heating by the heating means, the control means
sets a required number of revolutions of the internal combustion
engine higher than that when the coolant temperature is higher than
the predetermined reference.
[0032] According to another aspect of the present invention, an air
conditioner for a vehicle includes: a vapor compression
refrigeration cycle including a compressor for compressing and
discharging a refrigerant, the vapor compression refrigeration
cycle being configured to be switched to a cooler cycle for cooling
air to be blown into an interior of a vehicle compartment, and to a
heat pump cycle for heating the air to be blown into the interior
of the vehicle compartment; and control means adapted to stop the
compressor when a pressure of the refrigerant is lower than a
predetermined pressure. Furthermore, the control means set the
predetermined pressure smaller in the heat pump cycle, as compared
to in the cooler cycle. Thus, an operable range of the heat pump
cycle can be expanded to a low outside air temperature side, and a
refrigerant shortage can be accurately detected in a cooler
cycle.
[0033] In any air conditioner according to the above-described
invention, the control means may determine a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment, and may decrease and correct the target
coolant temperature when the electric heater is operated.
Alternatively, the control means may determine a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment, and may decrease and correct the target
coolant temperature based on power consumption of the electric
heater. In this case, the control means may cause a correction
amount for decreasing the target coolant temperature to be
increased as the power consumption of the electric heater becomes
larger. Alternatively, the air conditioner for a vehicle may
further include a seat heater disposed at a seat for generating
heat by being supplied with power. In this case, when the outside
air temperature is lower than the predetermined threshold, the
control means outputs an operation request signal to the seat
heater in addition to the internal combustion engine. Thus, a
passenger's feeling can be effectively improved even when the
temperature of the coolant is relatively low.
[0034] For example, in this case, the control means may determine a
target coolant temperature based on a target air temperature to be
blown into the vehicle compartment, and decreases and corrects the
target coolant temperature when the seat heater is operated. The
control means may determine a target coolant temperature based on a
target air temperature to be blown into the vehicle compartment,
and may decrease and correct the target coolant temperature based
on power consumption of the seat heater, and the control means may
cause a correction amount for decreasing the target coolant
temperature to be increased as the power consumption of the seat
heater becomes large.
[0035] According to another aspect of the present invention, an air
conditioner for a vehicle includes: heating means for heating air
to be blown into an interior of a vehicle compartment using a
coolant of an internal combustion engine as a heat source; an
electric heater for heating the air by being supplied with power;
and control means for determining a target coolant temperature
based on a target air temperature to be blown into the vehicle
compartment. In the air conditioner, the control means decreases
and corrects the target coolant temperature when the electric
heater is operated. Thus, it can prevent heating capacity from
being excessive, thereby effectively reducing fuel consumption.
[0036] According to another aspect of the present invention, an air
conditioner for a vehicle includes: heating means for heating air
to be blown into an interior of a vehicle compartment using a
coolant of an internal combustion engine as a heat source; an
electric heater for heating the air by being supplied with power;
and control means for determining a target coolant temperature
based on a target air temperature to be blown into the vehicle
compartment, and for decreasing and correcting the target coolant
temperature based on power consumption of the electric heater. In
the air conditioner, the control means increases a correction
amount for decreasing the target coolant temperature, as the power
consumption of the electric heater becomes larger. Thus, it can
prevent heating capacity from being excessive, thereby effectively
reducing fuel consumption.
[0037] According to another aspect of the present invention, an air
conditioner for a vehicle includes: heating means for heating air
to be blown into an interior of a vehicle compartment by using a
coolant of an internal combustion engine as a heat source; a seat
heater disposed at a seat for generating heat by being supplied
with power; and control means for determining a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment. In the air conditioner, the control means
decreases and corrects the target coolant temperature when the seat
heater is operated. Thus, when the seat heater is operated, the
warm feeling given to the passenger can be improved while the fuel
consumption can be improved.
[0038] According to another aspect of the present invention, an air
conditioner for a vehicle includes: heating means for heating air
to be blown into an interior of a vehicle compartment using a
coolant of an internal combustion engine as a heat source; a seat
heater disposed at a seat for generating heat by being supplied
with power; and control means for determining a target coolant
temperature based on a target air temperature to be blown into the
vehicle compartment, and for decreasing and correcting the target
coolant temperature based on power consumption of the seat heater.
In the air conditioner, as the power consumption of the seat heater
becomes larger, the control means increases a correction amount for
decreasing the target coolant temperature. Thus, when the seat
heater is operated, it can prevent warm feeling of a passenger from
being excessive, while the fuel consumption can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Additional objects and advantages of the present invention
will be more readily apparent from the following detailed
description of preferred embodiments when taken together with the
accompanying drawings. In which:
[0040] FIG. 1 is an entire configuration diagram showing an air
conditioner for a vehicle with a refrigerant circuit in a cooling
mode according to a first embodiment of the invention;
[0041] FIG. 2 is an entire configuration diagram showing the air
conditioner for a vehicle with a refrigerant circuit in a heating
mode according to the first embodiment;
[0042] FIG. 3 is an entire configuration diagram showing the air
conditioner for a vehicle with a refrigerant circuit in a first
dehumidification mode according to the first embodiment;
[0043] FIG. 4 is an entire configuration diagram showing the air
conditioner for a vehicle with a refrigerant circuit in a second
dehumidification mode according to the first embodiment;
[0044] FIG. 5 is a block diagram showing an electric controller of
the air conditioner for a vehicle in the first embodiment;
[0045] FIG. 6 is a flowchart showing control performed by the air
conditioner for a vehicle in the first embodiment;
[0046] FIG. 7 is a flowchart showing a detail control at step S14
of FIG. 6;
[0047] FIG. 8 is a diagram showing dehumidifying capacity and
heating capacity in respective operation modes of the air
conditioner for a vehicle in the first embodiment;
[0048] FIG. 9 is a flowchart showing a part of the control
performed by the air conditioner for a vehicle in the first
embodiment;
[0049] FIG. 10 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a second embodiment
of the invention;
[0050] FIG. 11 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a third embodiment of
the invention;
[0051] FIG. 12 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a fourth embodiment
of the invention;
[0052] FIG. 13A a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a fifth embodiment of
the invention, and FIGS. 13B and 13C are diagrams showing
respectively examples of the rule of the fuzzy theory, for
determining change amounts .DELTA.fC and .DELTA.fH;
[0053] FIG. 14 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a sixth embodiment of
the invention;
[0054] FIG. 15 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a seventh embodiment
of the invention;
[0055] FIG. 16 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to an eighth embodiment
of the invention; and
[0056] FIG. 17 a flowchart showing a part of control performed by
an air conditioner for a vehicle according to a ninth embodiment of
the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] Embodiments for carrying out the present invention will be
described hereafter referring to drawings. In the embodiments, a
part that corresponds to a matter described in a preceding
embodiment may be assigned with 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
[0058] A first embodiment of the invention will be described below
with reference to FIGS. 1 to 9. In the present embodiment, an air
conditioner for a vehicle of the invention is applied to the
so-called hybrid car which obtains a driving force for a vehicle
traveling from an internal combustion engine (engine) EG and an
electric motor for traveling. FIGS. 1 to 4 show an entire
configuration diagram of an air conditioner 1 for a vehicle,
according to the first embodiment and the following embodiments
described later.
[0059] The air conditioner for a vehicle includes a vapor
compression refrigeration cycle 10 which can switch among
refrigerant circuits in a cooling mode (COOL cycle) for cooling the
vehicle interior, in a heating mode (HOT cycle) for heating the
vehicle interior, and in a first dehumidification mode (DRY_EVA
cycle) and in a second dehumidification mode (DRY_ALL cycle) for
dehumidifying the vehicle interior. FIGS. 1 to 4 indicate the flows
of refrigerant in the cooling mode, the heating mode, the first
dehumidification mode, and the second dehumidification mode by
respective solid lines.
[0060] The cooling mode is an operation mode causing the
refrigeration cycle 10 to be in the COOL cycle, so as to have
cooling capacity and dehumidification capacity. Thus, the cooling
mode can be represented as a cooling dehumidification mode.
[0061] The heating mode and the first and second dehumidification
modes are modes in which the refrigeration cycle 10 is operated as
a heat pump cycle. In the three modes using the heat pump cycle,
the heating mode has a high heating capacity but does not have the
dehumidification capacity. Thus, the heating mode is used in a heat
pump cycle without dehumidifying.
[0062] In the three modes using the heat pump cycle, the first and
second dehumidification modes have the dehumidification capacity,
but have the heating capacity lower than that in the heating mode.
Thus, the first and second dehumidification modes are operated as a
heat pump cycle having the dehumidification capacity.
[0063] The first dehumidification mode is a dehumidification mode
which puts higher priority on a dehumidification capacity than a
heating capacity. The second dehumidification mode is a
dehumidification mode which puts higher priority on a heating
capacity than the dehumidification capacity. Therefore, the first
dehumidification mode can be represented by a low-temperature
dehumidification mode or a single dehumidification mode, and the
second dehumidification mode can be represented by a
high-temperature dehumidification mode or a dehumidification
heating mode.
[0064] FIG. 8 shows the dehumidification capacity and the heating
capacity in cooling mode, the heating mode, the first and second
dehumidification modes. That is, in the cooling mode, the
dehumidification capacity is large, but there is no the heating
capacity. Thus, when the cooling mode is selected in the heating, a
heating means (e.g., heater core 36, PTC heater 37 described
latter) other than the refrigeration cycle 10 is combined to be
operated.
[0065] In the heating mode, the heating capacity is large, but
there is no the dehumidification capacity. In the first
dehumidification mode, the dehumidification capacity is middle, but
the heating capacity is small. In the second dehumidification mode,
the dehumidification capacity is small, but the heating capacity is
middle.
[0066] The refrigeration cycle 10 includes a compressor 11, an
indoor condenser 12 and an indoor evaporator 26 serving as an
indoor heat exchanger, a thermal expansion valve 27 and a fixed
throttle 14 serving as decompression means for decompressing and
expanding refrigerant, and a plurality of (in the present
embodiment, five) electromagnetic valves 13, 17, 20, 21, 24, and
the like serving as refrigerant circuit switching means.
[0067] The refrigeration cycle 10 employs a normal flon-based
refrigerant as the refrigerant, and thus forms a subcritical
refrigeration cycle in which high-pressure side refrigerant
pressure does not exceed the critical pressure of the refrigerant.
Further, a refrigerating machine oil for lubricating the compressor
11 is mixed with the refrigerant. The refrigerating machine oil
circulates through the cycle together with the refrigerant.
[0068] The compressor 11 is positioned in an engine room, and is to
suck, compress, and discharge the refrigerant in the refrigeration
cycle 10. The compressor is an electric compressor which drives a
fixed displacement compressor mechanism 11a having a fixed
discharge capacity by using an electric motor 11b. Specifically,
various types of compressor mechanisms, such as a scroll type
compressor mechanism, or a vane compressor mechanism, can be
employed as the fixed displacement compressor mechanism 11a.
[0069] The electric motor 11b is an AC motor whose operation
(number of revolutions) is controlled by an AC voltage output from
an inverter 61. The inverter 61 outputs an AC voltage of a
frequency corresponding to a control signal output from an air
conditioning controller 50 to be described later. The control of
the number of revolutions changes a refrigerant discharge capacity
of the compressor 11. Thus, the electric motor 11b serves as
discharge capacity changing means of the compressor 11.
[0070] The refrigerant discharge side of the compressor 11 is
coupled to the refrigerant inlet side of the indoor condenser 12.
The indoor condenser 12 is disposed in a casing 31 forming an air
passage through which air flows into the vehicle interior in an
indoor air conditioning unit 30 of the air conditioner for a
vehicle. The indoor condenser 12 is a heat exchanger for heating
the air by exchanging heat between the refrigerant flowing
therethrough and the air having passed through an indoor evaporator
26 to be described later. The details of the indoor air
conditioning unit 30 will be described later.
[0071] The refrigerant outlet side of the indoor condenser 12 is
coupled to an electric three-way valve 13. The electric three-way
valve 13 is refrigerant circuit switching means its operation is
controlled by a control voltage output from the air conditioning
controller 50.
[0072] More specifically, in an energization state with power
supplied, the electric three-way valve 13 performs switching to a
refrigerant circuit coupling between the refrigerant outlet side of
the indoor condenser 12 and the refrigerant inlet side of the fixed
throttle 14. In a non-energization state without power supplied,
the three-way valve 13 performs switching to a refrigerant circuit
coupling between the refrigerant outlet side of the indoor
condenser 12 and one of refrigerant inlet and outlet ports of a
first three-way joint 15.
[0073] The fixed throttle 14 is decompression means for heating and
dehumidifying, and is adapted to decompress and expand the
refrigerant flowing from the electric three-way valve 13 in the
heating mode, and the first and second dehumidification modes. For
example, a capillary tube, an orifice, or the like can be adapted
as the fixed throttle 14. Alternatively, the decompression means
for heating and dehumidifying may employ an electric variable
throttle mechanism whose throttle passage area is adjusted by a
control signal output from the air conditioning controller 50. The
refrigerant outlet side of the fixed throttle 14 is coupled to one
of the refrigerant inflow/outlet ports of a three-way joint 23 to
be described later.
[0074] The first three-way joint 15 includes three refrigerant
inlet/outlet ports, and serves as a branch portion for branching a
refrigerant flow path. Such a three-way joint may be provided by
connecting refrigerant pipes, or by forming a plurality of
refrigerant passages in a metal block or resin block. Another
refrigerant inlet/outlet port of the first three-way joint 15 is
coupled to one of the refrigerant inlet/outlet ports of the outdoor
heat exchanger 16, and a further refrigerant inlet/outlet port of
the three-way joint 15 is coupled to the refrigerant inlet side of
the low-voltage electromagnetic valve 17.
[0075] The low-voltage electromagnetic valve 17 includes a valve
body for opening and closing a refrigerant flow path, and a
solenoid (coil) for driving the valve body. The electromagnetic
valve 17 is refrigerant circuit switching means whose operation is
controlled by a control voltage output from the air conditioning
controller 50. More specifically, the low-voltage electromagnetic
valve 17 is the so-called normally-closed type opening and closing
valve which is opened upon energization and closed upon
non-energization.
[0076] The refrigerant outlet side of the low-voltage
electromagnetic valve 17 is coupled to one of the refrigerant
inlet/outlet ports of a fifth three-way joint 28 to be described
later via a first check valve 18. The first check valve 18 allows
only the refrigerant to flow from the low-voltage electromagnetic
valve 17 to the fifth three-way joint 28.
[0077] The outdoor heat exchanger 16 is disposed in the engine
room, and is to exchange heat between the refrigerant flowing
therethrough and air (i.e., outside air) outside a vehicle
compartment blown from a blower fan 16a. The blower fan 16a is an
electric blower whose number of revolutions (amount of air) is
controlled by a control voltage output from the air conditioning
controller 50.
[0078] The blower fan 16a of the present embodiment blows the
outside air not only to the outdoor heat exchanger 16, but also to
a radiator (not shown) for radiating heat from coolant of the
engine EG. Specifically, the air outside the vehicle compartment
blown from the blower fan 16a flows through the outdoor heat
exchanger 16 and the radiator in that order.
[0079] In coolant circuits indicated by broken lines shown in FIGS.
1 to 4, a coolant pump (not shown) is provided for allowing a
coolant to circulate therethrough. The coolant pump is an electric
water pump whose number of revolutions (amount of coolant
circulating) is controlled by a control voltage output from the air
conditioning controller 50.
[0080] The other one of the refrigerant inlet/outlet ports of the
outdoor heat exchanger 16 is coupled to one of the refrigerant
inlet/outlet ports of the second three-way joint 19. The basic
structure of the second three-way joint 19 is the same as that of
the first three-way joint 15. Another one of the refrigerant
inlet/outlet ports of the second three-way joint 19 is coupled to
the refrigerant inlet side of the high-voltage electromagnetic
valve 20, and a further one of the refrigerant inlet/outlet ports
is coupled to one of the refrigerant inlet and outlet ports of the
electromagnetic valve 21 for interruption of the heat
exchanger.
[0081] The high-voltage electromagnetic valve 20 and the
heat-exchanger interruption electromagnetic valve 21 are
refrigerant circuit switching means whose operation is controlled
by a control voltage output from the air conditioning controller
50. The basic structure of the valves 20 and 21 is the same as that
of the low-voltage electromagnetic valve 17. The high-voltage
electromagnetic valve 20 and the heat-exchanger interruption
electromagnetic valve 21 are formed as the so-called
normally-opened type opening and closing valve designed to be
closed upon energization and opened upon non-energization.
[0082] The refrigerant outlet side of the high-voltage
electromagnetic valve 20 is coupled to an inlet of a throttle
mechanism of a thermal expansion valve 27 to be described later via
a second check valve 22. The second check vale 22 allows only the
refrigerant to flow from the high-voltage electromagnetic valve 20
to the thermal expansion valve 27.
[0083] The other one of the refrigerant inlet/outlet ports of the
heat exchanger interruption electromagnetic vale 21 is coupled to
one of the refrigerant inlet/outlet ports of the third three-way
joint 23. The basic structure of the third three-way joint 23 is
the same as that of the first three-way joint 15. Another one of
the refrigerant inlet/outlet ports of the third three-way joint 23
is coupled to the refrigerant outlet side of the fixed throttle 14
as mentioned above. A further one of the refrigerant inlet/outlet
ports of the joint 23 is coupled to the refrigerant inlet side of
the dehumidifying electromagnetic valve 24.
[0084] The dehumidifying electromagnetic valve 24 is refrigerant
circuit switching means whose operation is controlled by a control
voltage output from the air conditioning controller 50. The basic
structure of the valve 24 is the same as that of the low-voltage
electromagnetic valve 17. The dehumidifying electromagnetic valve
24 also serves as a normally-closed type opening and closing valve.
The refrigerant circuit switching means of the present embodiment
is comprised of (five) electromagnetic valves which are adapted to
be brought into a predetermined opened or closed state when the
supply of power is stopped. The electromagnetic valves include the
electric three-way valve 13, the low-voltage electromagnetic valve
17, the high-voltage electromagnetic valve 20, the heat exchanger
interruption electromagnetic valve 21, and the dehumidifying
electromagnetic valve 24.
[0085] The refrigerant outlet side of the dehumidifying
electromagnetic valve 24 is coupled to one of the refrigerant
inlet/outlet ports of a fourth three-way joint 25. The basic
structure of the fourth three-way joint 25 is the same as that of
the first three-way joint 15. Another one of the refrigerant
inlet/outlet ports of the fourth three-way joint 25 is coupled to
the outlet side of the throttle mechanism of the thermal expansion
valve 27, and a further one of the refrigerant inlet/outlet ports
is coupled to the refrigerant inlet side of the indoor evaporator
26.
[0086] The indoor evaporator 26 is disposed on the upstream side of
the air flow of the indoor condenser 12 in a casing 31 of the
indoor air conditioning unit 30. The indoor evaporator 26 is a heat
exchanger for cooling air by exchanging heat between the air and
the refrigerant flowing therethrough.
[0087] The refrigerant outlet side of the indoor evaporator 26 is
coupled to the inlet side of a temperature sensing portion of the
thermal expansion valve 27. The thermal expansion valve 27 is
decompression means for cooling which decompresses and expands the
refrigerant flowing from the inlet of the throttle mechanism
thereinto to allow the refrigerant to flow outward from the outlet
of the throttle mechanism.
[0088] More specifically, the thermal expansion valve 27 used in
the present embodiment is an internal pressure equalizing expansion
valve which accommodates in one housing, a temperature sensing
portion 27a and a variable throttle mechanism 27b. The temperature
sensing portion 27a is provided for detecting the degree of
superheat of the refrigerant on the outlet side of the indoor
evaporator 26 based on the temperature and pressure of the
refrigerant on the outlet side of the indoor evaporator 26. The
variable throttle mechanism 27b is provided for adjusting a
throttle passage area (refrigerant flow rate) based on a
displacement of the temperature sensing portion 27a such that the
superheat degree of the refrigerant on the outlet side of the
evaporator 26 is in a predetermined range.
[0089] The outlet side of the temperature sensing portion of the
thermal expansion valve 27 is coupled to one of the refrigerant
inlet and outlet ports of the fifth three-way joint 28. The basic
structure of the fifth three-way joint 28 is the same as that of
the first three-way joint 15. As mentioned above, another one of
the refrigerant inlet and outlet ports of the fifth three-way joint
28 is coupled to the refrigerant outlet side of the fifth check
valve 18, and a further one of the refrigerant inlet and outlet
ports is coupled to the refrigerant inlet side of an accumulator
29.
[0090] The accumulator 29 is a low-pressure side vapor-liquid
separator which is adapted to separate the refrigerant flowing
thereinto from the fifth three-way joint 28 and to store the
excessive refrigerant. The vapor-phase refrigerant outlet of the
accumulator 29 is coupled to a refrigerant suction port of the
compressor 11.
[0091] Now, the indoor air conditioning unit 30 will be described
below. The indoor air conditioning unit 30 is disposed inside a
gauge board (i.e., instrument panel) at the foremost part of the
interior of the vehicle. The unit 30 accommodates in the casing 31
serving as an outer envelope, a blower 32, the above-mentioned
indoor evaporator 26, the indoor condenser 12, a heater core 36, a
PTC heater 37, and the like.
[0092] The casing 31 forms an air passage of air blown into the
vehicle interior. The casing 31 is formed of resin (for example,
polypropylene) having some degree of elasticity and excellent
strength. An inside/outside air switching box 40 for switching
between an inside air (i.e., air inside the vehicle compartment)
and an outside air (i.e., air outside the vehicle compartment) to
introduce the selected air is disposed on the most upstream side of
the air flow in the casing 31.
[0093] More specifically, the inside/outside air switching box 40
is provided with an inside air inlet 40a for introducing the inside
air into the casing 31, and an outside air inlet 40b for
introducing the outside air thereinto. The inside/outside air
switching box 40 has therein an inside/outside air switching door
40c for changing the ratio of an amount of the inside air to an
amount of the outside air by continuously adjusting opening areas
of the inside air inlet 40a and outside air inlet 40b.
[0094] The inside/outside air switching door 40c serves as air
amount ratio changing means for switching among suction port modes
to change the ratio of the inside air amount to the outside air
amount introduced into the casing 31. More specifically, the
inside/outside air switching door 40c is driven by an electric
actuator 62 for the inside/outside air switching door 40c. The
electric actuator 62 has its operation controlled by a control
signal output from the air conditioning controller 50.
[0095] The suction port modes include an inside air mode, an
outside air mode, and an inside and outside air mixing mode. In the
inside air mode, the inside air is introduced into the casing 31 by
fully opening the inside air inlet 40a, while completely closing
the outside air inlet 40b. In the outside air mode, the outside air
is introduced into the casing 31 by completely closing the inside
air inlet 40a, while fully opening the outside air inlet 40b. In
the inside and outside air mixing mode, the ratio of an introduced
amount of inside air to an introduced amount of outside air is
continuously changed by adjusting the opening areas of the inside
air inlet 40a and outside air inlet 40b in a continuous manner
between the inside air mode and the outside air mode.
[0096] The blower 32 for blowing air sucked via the inside/outside
air switching box 40 into the vehicle interior is disposed on the
downstream side of the air flow of the inside/outside air switching
box 40. The blower 32 is an electric blower which includes a
centrifugal multiblade fan (e.g., sirocco fan) driven by an
electric motor, and whose number of revolutions is controlled by
the control voltage output from the air conditioning controller 50,
thereby controlling air blowing amount.
[0097] The indoor evaporator 26 is disposed on the downstream side
of the air flow of the blower 32. Further, a heating air passage 33
for allowing air passing through the indoor evaporator 26 to flow
therethrough, an air passage including a cool air bypath passage
34, and a mixing space 35 for mixing air from the heating air
passage 33 and the cool air bypass passage 34 are formed on the
downstream side of the air flow of the indoor evaporator 26.
[0098] In the heating air passage 33, the heater core 36, the
indoor condenser 12, and the PTC heater 37 are arranged in that
order along the direction of air flow so as to serve as heating
means for heating air passing through the indoor evaporator 26. The
heater core 36 and the PTC heater 37 can be adapted as a heating
means for heating air by using a heat source other than the
refrigerant.
[0099] The heater core 36 is a heat exchanger for heating air
having passed through the indoor evaporator 26 by exchanging heat
between coolant of the engine EG for outputting a driving force for
vehicle traveling, and air having passed through the indoor
evaporator 26.
[0100] The PTC heater 37 is an electric heater with a PTC element
(positive characteristic thermistor) which produces heat by being
supplied with power thereby to heat air having passed through the
indoor condenser 12. The air conditioner is provided with a
plurality of (specifically, three) PTC heaters 37. The air
conditioning controller 50 controls the heating capacity of the
whole PTC heaters 37 by changing the number of the PTC heaters 37
energized.
[0101] On the other hand, the cool air bypass passage 34 is an air
passage for allowing the air having passed through the indoor
evaporator 26 to be introduced into the mixing space 35 without
passing through the heater core 36, the indoor condenser 12, and
the PTC heater 37. Thus, the temperature of the air mixed in the
mixing space 35 is changed by the ratio of the amount of air
passing through the heating air passage 33 to the amount of air
passing through the cool bypass passage 34.
[0102] In the present embodiment, an air mix door 38 is provided
for continuously changing the ratio of the amount of cool air
flowing into the heating air passage 33 to that of cool air flowing
into the cool air bypass passage 34, on the downstream side of the
air flow of the indoor evaporator 26, and on the inlet sides of the
heating air passage 33 and the cool air bypass passage 34.
[0103] Thus, the air mix door 38 serves as temperature adjustment
means for adjusting the temperature of air in the mixing space 35,
thereby adjusting temperature of air blown into the vehicle
interior. More specifically, the air mix door 38 is driven by an
electric actuator 63 for the air mix door. The electric actuator 63
has its operation controlled by a control signal output from the
air conditioning controller 50.
[0104] Air outlets 41-43 for blowing the air, whose temperature is
adjusted, from the mixing space 35 into the vehicle interior as a
space to be cooled are disposed on the most downstream side of the
air flow in the casing 31. The air outlets 41-43 include;
specifically, a face air outlet 41 from which conditioned air is
blown toward an upper body of a passenger in the vehicle
compartment, a foot air outlet 42 from which conditioned air is
blown toward a foot of the passenger, and a defroster air outlet 43
from which conditioned air is blown toward the inner side of a
front windowpane of the vehicle.
[0105] A face door 41a for adjusting the area of an opening of the
face air outlet 41 is positioned on the upstream side of the air
flow of the face air outlet. A foot door 42a for adjusting the area
of an opening of the foot air outlet 42 is positioned on the
upstream side of the air flow of the foot air outlet 42. A
defroster door 43a for adjusting the area of an opening of the
defroster air outlet 43 is positioned on the upstream side of the
air flow of the defroster air outlet 43.
[0106] The face door 41a, the foot door 42a, and the defroster door
43a serve as air outlet mode switching means for switching among
air outlet modes, and are rotatably operated in connection and
cooperation with the electric actuator 64 for driving the air
outlet mode door via a link mechanism (not shown). The electric
actuator 64 also has its operation controlled by the control signal
output from the air conditioning controller 50.
[0107] The air outlet modes include a face mode, a bi-level mode, a
foot mode, and a foot/defroster mode. In the face mode, air is
blown from the face air outlet 41 toward the upper body of the
passenger in the vehicle compartment by fully opening the face air
outlet 41. In the bi-level mode, air is blown toward the upper body
and foot of the passenger in the vehicle compartment by fully
opening both of the face air outlet 41 and the foot air outlet 42.
In the foot mode, air is blown mainly from the foot air outlet 42
by fully opening the foot air outlet 42, while opening the
defroster air outlet 43 to a small degree of opening. In the
foot/defroster mode, air is blown from both the foot air outlet 42
and the defroster air outlet 43 by opening the foot air outlet 42
and the defroster air outlet 43 to the same degree.
[0108] An air outlet mode switch 60c of an operation panel 60 to be
described later is manually operated by the passenger, so that the
defroster air outlet 43 is fully opened thereby to enable setting
of a defroster mode for blowing air from the defroster air outlet
43 toward the inner face of the front windowpane of the
vehicle.
[0109] When the foot mode is selected as the air outlet mode, air
is blown from at least the foot air outlet 42. When the
foot/defroster mode or the defroster mode is selected, a flow
amount ratio of air blown from the defroster air outlet 43 is made
larger than that in the foot mode, thereby preventing defogging in
the front windowpane of the vehicle. Thus, the foot/defroster mode
and the defroster mode are adapted as a defogging mode.
[0110] A hybrid car to which the air conditioner 1 for a vehicle of
the present embodiment is applied includes an electric heating
defogger 47 and a seat heating device 48, in addition to the air
conditioner for a vehicle. The electric heating defogger 47 is a
heating wire disposed inside or on the surface of the inner face of
the windowpane in the vehicle compartment, and is to prevent fog or
to defog by heating the windowpane. Also, the electric heating
defogger 47 can have its operation controlled by a control signal
output from the air conditioning controller 50.
[0111] The seat heating device 48 is disposed inside or on the
surface of the seat of the vehicle compartment, to directly warm
the body of a passenger, so as to improve the heating feeling. In
the present embodiment, the seat heating device 48 is a heating
wire that generates heat by electrical current.
[0112] The operation of the electrical heating defogger 47 and the
seat heating device 48 can be controlled by control signals output
from the air conditioning controller 50.
[0113] Now, an electric controller of the present embodiment will
be described below with reference to FIG. 5. The air conditioning
controller 50 is configured by a known microcomputer, including
CPU, ROM, and RAM, and a peripheral circuit thererof. The
controller 50 performs various kinds of computations and processing
based on air conditioning control programs stored in the ROM
thereby to control the operations of the inverter 61 for the
electric motor 11b of the compressor 11 coupled to the output side,
the respective electromagnetic valves 13, 17, 20, 21, and 24
serving as the refrigerant circuit switching means, the blower fan
16a, the blower 32, and various types of electric actuators 62, 63,
64 or the like.
[0114] The air conditioning controller 50 has the control means for
controlling the above various components integrated therewith. In
the present embodiment, especially, the air conditioning controller
50 is configured to perform a switch control of the cooling mode,
the heating mode, and the first and second dehumidification
modes.
[0115] In the present embodiment, the air conditioning controller
50 includes therein a discharge capacity control means 50a adapted
to control operation of the electrical motor 11b that is a
discharge capacity changing means of the compressor 11. The
discharge capacity control means may be configured separately from
the air conditioning controller 50.
[0116] Detection signals from a group of sensors are input to the
input side of the air conditioning controller 50. The sensors
include an inside air sensor 51 for detecting, a temperature Tr of
the interior of the vehicle, an outside air sensor 52 (outside air
temperature detection means) for detecting an outside air
temperature Tam, and a solar radiation sensor 53 for detecting an
amount of solar radiation Ts in the vehicle interior. And, the
sensors also include a discharge temperature sensor 54 (discharge
temperature detection means) for detecting a discharged refrigerant
temperature Td of the compressor 11, and a discharge pressure
sensor 55 (discharge pressure detection means) for detecting a
refrigerant pressure Pd on the discharge side (high-pressure side
refrigerant pressure) of the compressor 11. Further, the sensors
include an evaporator temperature sensor 56 (evaporator temperature
detection means) for detecting a blown-air temperature (evaporator
temperature) Te of air from the indoor evaporator 26, and a suction
temperature sensor 57 for detecting a temperature Tsi of the
refrigerant flowing through between the first three-way joint 15
and the low-pressure electromagnetic valve 17. Moreover, the
sensors include a coolant temperature sensor for detecting an
engine coolant temperature Tw, and a RHW sensor 45 for detecting a
relative humidity RHW of air in the vehicle interior near the
windowpane therein or on the windowpane.
[0117] Specifically, the evaporator temperature sensor 56 detects
the temperature of a heat exchanging fin of the indoor evaporator
26. Temperature detection means for detecting the temperature of
other parts of the indoor evaporator 26 may be employed as the
evaporator temperature sensor 56. Alternatively, temperature
detection means for directly detecting the temperature of
refrigerant itself flowing through the indoor evaporator 26 may be
employed as the evaporator temperature sensor 56.
[0118] The RHW sensor 45 is configured by three sensors such as a
humidity sensor for detecting a relative humidity RHW of air in the
vehicle compartment near the windowpane of the vehicle, a
near-windowpane temperature sensor for detecting an air temperature
in the vehicle compartment near the windowpane, and a windowpane
surface temperature sensor for detecting a surface temperature of
the windowpane.
[0119] In the present embodiment, the RHW sensor 45 is arranged on
the surface of the windowpane of the vehicle, at a side position of
the rearview mirror that is positioned at a center upper portion of
the windowpane of the vehicle, for example.
[0120] The input side of the air conditioning controller 50
receives input of an operation signal from each of various types of
air conditioning operation switches provided in the operation panel
60 disposed near the instrument panel on the front side of the
vehicle compartment. Various types of air conditioning operation
switches provided in the operation panel 60 include, specifically,
an operation switch (not shown) for the air conditioner 1 for a
vehicle, an air conditioning switch 60a for switching on/off of the
compressor 11 thereby switching on/off of the air conditioning, an
automatic switch (not shown) for setting and releasing an automatic
control of the air conditioner 1, a selector switch for an
operating mode, a suction mode switch 60b for selectively switching
an air suction mode, the air outlet mode switch 60c for selecting
an air outlet mode, an air amount setting switch for the blower 32,
a vehicle interior temperature setting switch, an economy switch
for outputting a command for giving higher priority on power saving
of the refrigeration cycle, or the like.
[0121] Next, the operation of the present embodiment with the
above-mentioned arrangement will be described below with reference
to FIG. 6. FIG. 6 is a flowchart showing control processing
performed by the air conditioner 1 for a vehicle in the present
embodiment. The control processing is performed by the supply of
power from a battery to the air conditioning controller 50 even
when a vehicle system is stopped.
[0122] First, in step S1, it is determined whether or not a start
switch for pre-air conditioning, or an operation switch for the air
conditioner 1 for a vehicle on the operation panel 60 is turned on
(ON). When the start switch for the pre-air conditioning or the
operation switch for the air conditioner for a vehicle is turned
on, the operation proceeds to step S2.
[0123] The pre-air conditioning is the control of air conditioning,
which starts air conditioning in the vehicle compartment before the
passenger rides on the vehicle. The start switch for the pre-air
conditioning is provided in a wireless terminal (i.e., remote
controller) carried by the passenger. Thus, the passenger can
initiate the air conditioner 1 for a vehicle from a location away
from the vehicle.
[0124] Further, the hybrid car to which the air conditioner 1 for a
vehicle of the present embodiment is applied can supply power from
a commercial power source (i.e., external power source) to a batter
thereby to charge the battery. When the vehicle is connected to the
external power source, the pre-air conditioning is performed only
for a predetermined time (for example, 30 minutes). In contrast,
when the vehicle is not connected to the external power source, the
pre-air conditioning is performed until a remaining battery level
becomes a predetermined value or less.
[0125] In step S2, a flag, a timer, a control variable, and the
like are initialized (initialization). And, initial alignment of a
stepping motor included in the above electric actuator and the like
is performed.
[0126] In next step S3, an operation signal is read from the
operation panel 60, and then the operation proceeds to step S4.
Specifically, the operation signals include a vehicle interior
preset temperature Tset set by a vehicle interior temperature
setting switch, a selection signal of the air outlet mode, a
selection signal of the suction port mode, a setting signal of the
amount of air from the blower 32, and the like.
[0127] In step S4, signals regarding the circumstances of the
vehicle used for the air conditioning control, that is, detection
signals from the above group of sensors 51 to 57 are read, and then
the operation proceeds to step S5. In step S5, a target outlet air
temperature TAO of blown air into the vehicle interior is
calculated. Further, in the heating mode, a target heat-exchanger
temperature for heating is calculated. The target outlet air
temperature TAO is calculated by the following equation F1:
TAO=Kset.times.Tset-Kr.times.Tr-Kam.times.Tam-Ks.times.Ts+C
(F1)
where Tsct is a vehicle interior preset temperature set by the
vehicle interior temperature setting switch, Tr is an inside air
temperature detected by the inside air sensor 51, Tam is an outside
air temperature detected by the outside air sensor 52, and Ts is an
amount of solar radiation detected by the solar radiation sensor
53. The Kset, Kr, Kam, and Ks are control gains, and C is a
constant for correction.
[0128] The target heat exchanger temperature for heating is a value
basically calculated by the above formula F1. In some cases, the
target temperature is often corrected to be set to a value lower
than the TAO calculated by the formula F1 so as to restrict the
power consumption.
[0129] In the subsequent steps S6 to S16, control states of various
devices coupled to the air conditioning controller 50 are
determined. In step S6, one mode is selected from among the cooling
mode, the heating mode, the first dehumidification mode, and the
second dehumidification mode, and the presence or absence of
energization of the PTC heater 37 is determined, based on the air
conditioning environmental state. The details of step S6 will be
described later.
[0130] In step S7 of FIG. 6, the target air amount of air blown by
the blower 32 is determined. Specifically, a blower motor voltage
to be applied to the electric motor is determined with reference to
a control map previously stored in the air conditioning controller
50 based on the TAO determined in step S4.
[0131] In more detail, in the present embodiment, the blower motor
voltage is set to a high voltage near the maximum value thereof in
an extreme-low temperature range (i.e., maximum cooling range) and
an extreme-high temperature range (i.e., maximum heating range) of
the TAO, so that the amount of air from the blower 32 is controlled
to a level near the maximum amount thereof. As the TAO increases
from the extreme-low temperature range toward the intermediate
temperature range, the blower motor voltage is decreased with
increasing TAO, thereby resulting in a decrease in the amount of
air from the blower 32.
[0132] Further, as the TAO decreases from the extreme-high
temperature range to, the intermediate temperature range, the
blower motor voltage is decreased based on a decrease of TAO,
resulting in a decrease in the amount of air from the blower 32.
When the TAO is positioned within a predetermined intermediate
temperature range, the blower motor voltage is minimized, and thus
the amount of air from the blower 32 is also minimized.
[0133] In step S8, a suction port mode, that is, a switching state
of the inside/outside air switching box is determined. The suction
port mode is also determined based on the TAO with reference to a
control map previously stored in the air conditioning controller
50. The present embodiment basically gives higher priority on the
outside air mode for introducing the outside air, but selects the
inside air mode for introducing the inside air when the TAO exists
in the extreme-low temperature range and a high cooling capacity is
required to be obtained. Exhaust gas concentration detection means
is provided for detecting an exhaust gas concentration of the
outside air. When an exhaust gas concentration is equal to or more
than a predetermined reference concentration, the inside air mode
may be selected.
[0134] In step S9, an air outlet mode is determined. The air outlet
mode is also determined based on the TAO with reference to a
control map previously stored in the air conditioning controller
50. In the present embodiment, as the TAO increases from the low
temperature range to the high temperature range, the air outlet
mode is switched in turn from the foot mode to the bi-level mode,
and then to the face mode.
[0135] Thus, the face mode is mainly selected in summer, the
bi-level mode is mainly selected in both spring and autumn, and the
foot mode is mainly selected in winter. When the possibility of
fogging of the windowpane is determined to be high based on a
relative humidity RHW of the surface of the windowpane detected by
the humidity sensor or the like, the foot/defroster mode or
defroster mode may be selected.
[0136] In step S10, a target opening degree SW of the air mix door
38 is calculated based on the TAO, an evaporator blown-air
temperature Te of the air from the indoor evaporator 26 detected by
the evaporator temperature sensor 56, and a heater temperature.
[0137] The heater temperature is a value determined based on the
heating capacity of heating means (e.g., heater core 36, indoor
condenser 12, and PTC heater 37) disposed in a heating air passage
33. An engine coolant temperature Tw can be generally used as the
heater temperature. Thus, the target opening degree SW can be
calculated by the following formula F2:
SW=[(TAO-Te)/(Tw-Te)].times.100(%) (F2)
[0138] The case of SW=0(%) indicates the maximum cooling position
of the air mix door 38 in which the cool air bypass passage 34 is
fully opened, and the heating air passage 33 is completely closed.
In contrast, the case of SW=100% indicates the maximum heating
position of the air mix door 38 in which the cool air bypass
passage 34 is completely closed, and the heating air passage 33 is
fully opened.
[0139] In step S11, a refrigerant discharge capacity (specifically,
the number of revolutions) of the compressor 11 is determined. The
way to determine the basic number of revolutions of the compressor
11 will be described below. For example, in the cooling mode, a
target evaporator blown-air temperature TEO of the evaporator
blown-air temperature Te of the air from the indoor evaporator 26
is determined based on the TAO or the like determined in step S4
with reference to the control map previously stored by the air
conditioning controller 50.
[0140] A deviation En (TEO-Te) between the target evaporator
blown-air temperature TEO and the evaporator blown-air temperature
Te is calculated. The deviation En-1 previously calculated is
subtracted from the deviation En currently calculated thereby to
determine the rate of change in deviation Edot (En-(En-1)). Such
deviation En and deviation change rate Edot are used to determine
an amount of change in number of revolutions .DELTA.fC of the
compressor with respect to the previous number of revolutions fCn-1
of the compressor according to fuzzy inference based on a
membership function and rule previously stored by the air
conditioning controller 50.
[0141] In the heating mode, a target high pressure PDO of a
discharge side refrigerant pressure (high-pressure side refrigerant
pressure) Pd is determined based on the target heat exchanger
temperature for heating or the like determined in step S4 with
reference to a control map previously stored in the air
conditioning controller 50. A deviation Pn (PDO-Pd) between the
target high pressure PDO and the discharge side refrigerant
pressure Pd is calculated. The use of the deviation Pn and a rate
of change in deviation Pdot (Pn-(Pn-1)) with reference to the
deviation Pn-1 previously calculated determines an amount of change
in number of revolutions .DELTA.fH with respect to the previous
number of revolutions fHn-1 of the compressor based on the fuzzy
inference.
[0142] In step S12 shown in FIG. 6, an operating rate (e.g., number
of revolutions) of the blower fan 16a for blowing outside air
toward the outdoor heat exchanger 16 is determined in step S12
shown in FIG. 6. A determination method of the operating rate
(number of revolutions) of the basic blower fan 16a of the present
embodiment is as follows. That is, a first temporary operating rate
(number of revolutions) of the blower fan 16a is determined in such
a manner that the operating rate (number of revolutions) of the
blower fan 16a increases with increasing discharge refrigerant
temperature Td of the compressor 11. A second temporary operating
rate (number of revolutions) of the blower fan 16a is determined in
such a manner that the operating rate (number of revolutions) of
the blower fan 16a increases with increasing engine coolant
temperature Tw.
[0143] A larger one of the first and second temporary operating
rates (numbers of revolutions) is selected. The selected operating
rate (number of revolution) is corrected taking into consideration
reduction of noise of the solar fan 16a and vehicle speed, and the
corrected value is determined as the operating rate (number of
revolutions) of the blower fan 16a.
[0144] In step S13, the number of the operated PTC heaters 37 is
determined, and the operated state of the electric heating defogger
47 is also determined. For example, in some cases, the target heat
exchanger temperature for heating cannot be obtained even at the
target opening degree SW of the air mix door 38 of 100% in the
heating mode when the energization of the PTC heaters 37 is
determined to be necessary in step S6. In such cases, the number of
the operated PTC heaters 37 may as well be determined based on a
difference between the inside air temperature Tr and the target
heat exchanger temperature for heating.
[0145] When there is high possibility of formation of fogging on
the windowpane due to the humidity and temperature of the interior
of the vehicle, or when fogging occurs on the windowpane, the
electric heating defogger 47 is activated.
[0146] Then, in step S14, the operated states of the respective
electromagnetic valves 13, 17, 20, 21, 24 serving as refrigerant
circuit switching means are determined based on the operating mode
determined in the above step S6. At this time, the present
embodiment achieves the refrigerant circuit according to the
operation mode. Some electromagnetic valves are controlled to open
the refrigerant flow paths through which refrigerant flows, and the
other electromagnetic valves are brought into a non-energization
state for the refrigerant flow paths through which refrigerant does
not flow, depending on the level of the refrigerant pressure,
thereby reducing power consumption.
[0147] The details of the process in step S14 will be described
below using the flowchart of FIG. 7. First, in step S14a, the
operating mode determined in step S6 is read into a memory
CYCLE_VALVE. Then, in step S14b, it is determined whether the air
conditioner 1 for a vehicle is stopped or not, that is, whether air
conditioning in the vehicle interior is performed or not.
[0148] When the air conditioner 1 for a vehicle is determined to be
stopped in step S14b, the memory CYCLE_VALVE is set in the cooling
mode (COOL cycle) in step S14c. Then, the operation proceeds to
step S14d. When the air conditioning 1 for a vehicle is determined
not to be stopped in step S14b, the operation proceeds to step
S14d.
[0149] The phrase "air conditioner 1 for a vehicle is stopped"
which is determined in step S14b means not only that the operation
switch for the air conditioner 1 for a vehicle on the operation
panel 60 is turned OFF, but also that the amount of air from the
blower 32 is set to 0 by an air amount setting switch on the
operation panel 60, that is, that the vehicle system itself is
stopped.
[0150] In step S14d, the operated states of the respective
electromagnetic valves 13, 17, 20, 21, 24 are determined.
Specifically, when the memory CYCLE_VALVE is set in the cooling
mode (COOL cycle), all electromagnetic valves are brought into the
non-conductive state. When the memory CYCLE_VALVE is set to the
heating mode (HOT cycle), the electric three-way valve 13, the
high-pressure electromagnetic valve 20, and the low-pressure
electromagnetic valve 17 are brought into the energization state,
and the remaining electromagnetic valves 21 and 24 are brought into
the non-energization state. When the memory CYCLE_VALVE is set to
the first dehumidification mode (DRY_EVA cycle), the electric
three-way valve 13, the low-pressure electromagnetic valve 17, the
dehumidification electromagnetic valve 24, and the heat exchanger
interruption electromagnetic valve 21 are brought into the
energization state, and the high-pressure electromagnetic valve 20
is brought into the non-energization state. When the memory
CYCLE_VALVE is set to the second dehumidification mode (DRY_ALL
cycle), the electric three-way valve 13, the low-pressure
electromagnetic valve 17, and the dehumidification electromagnetic
valve 24 are brought into the energization state, and the remaining
electromagnetic valves 20 and 21 are brought into the
non-energization state.
[0151] That is, in the present embodiment, even when switching to
the refrigerant circuit of any one of the operating modes, the
supply of power to at least one of the electromagnetic valves 13,
17, 20, 21, 24 is stopped.
[0152] In step S15, the presence or absence of an operation request
of the engine EG is determined. Since a general vehicle designed to
obtain a driving force for vehicle traveling only from the engine
EG constantly operates the engine, the engine coolant is constantly
at high temperature. Thus, a general air conditioner for the
vehicle can exhibit the sufficient heating capacity by allowing the
engine coolant to flow through the heater core 36.
[0153] In contrast, the hybrid car, such as that to which the
embodiment of the invention is applied, can travel by the driving
force for traveling obtained only from the electric motor for
traveling as long as the remaining battery level is sufficient.
Thus, when the engine EG is stopped, the temperature of the engine
coolant is increased only up to about 40.degree. C. if the high
heating capacity is required. Therefore, the heater core 36 cannot
exhibit sufficient heating capacity.
[0154] In the present embodiment, in order to ensure the heat
source required for the heating by using the heater core 36, a
request signal for activating the engine EG is output from the air
conditioning controller 50 to an engine controller (not shown) to
be used for control of the engine EG at the engine coolant
temperature Tw lower than a predetermined reference coolant
temperature even when the high heating capacity is required.
[0155] Thus, the engine coolant temperature Tw is increased thereby
to provide the high heating capacity. Such an operation request
signal of the engine EG causes the engine EG to be activated even
when the engine EG does not need to be operated as a driving source
for the vehicle traveling, thereby deteriorating the fuel
efficiency of the vehicle. Thus, it is desirable that a frequency
of outputting the operation request signal for the engine EG is
reduced as much as possible.
[0156] In step S16, when frost is formed at the outdoor heat
exchanger 16, the control of defrosting the outdoor heat exchanger
16 is performed. It is known that when the outdoor heat exchanger
16 absorbs heat from the refrigerant, as in the refrigerant circuit
in the heating mode, a decrease in refrigerant evaporation
temperature at the outdoor heat exchanger 16 down to about
-12.degree. C. forms frost at the outdoor heat exchanger 16.
[0157] Such formation of frost makes it difficult for the air
outside the vehicle compartment to flow through the outdoor heat
exchanger 16, so that the outdoor heat exchanger 16 cannot exchange
heat between the refrigerant and the air outside the vehicle
compartment. Thus, when frost is formed at the outdoor heat
exchanger 16, a control process of forcedly bringing the
refrigerant circuit into the cooling mode is performed. Since the
high-pressure refrigerant dissipates heat at the outdoor heat
exchanger 16 as described later, the frost formed at the outdoor
heat exchanger 16 can be melted at the refrigerant circuit in the
cooling mode.
[0158] In step S17, control signals and control voltages are output
by the air conditioning controller 50 to various types of
components 61, 13, 17, 20, 21, 24, 16a, 32, 62, 63, and 64. For
example, a control signal is output to an inverter 61 for the
electric motor 11b of the compressor 11 such that the number of
revolutions of the compressor 11 becomes the number of revolutions
determined in step S11.
[0159] In step S18 shown in FIG. 6, the operation is held during a
control cycle .tau.. When the control cycle .tau. is determined to
elapse, the operation returns to step S3. In the present
embodiment, the control cycle .tau. is set to 250 ms. This is
because the air conditioning controllability of the vehicle
interior is not adversely affected even due to a long control cycle
as compared to the engine control or the like. Further, the volume
of communication for the air conditioning control in the vehicle
interior is restricted, and thus the volume of communication in a
control system which needs to perform the high-speed control can be
sufficiently ensured, as in the engine control or the like.
[0160] Now, the process in step S6 described above will be
described in more detail below. FIG. 9 is a flowchart showing a
part of the process in step S6. The control process shown in the
flowchart of FIG. 9 are carried out when an air conditioner switch
60a and an automatic switch 60b are turned on (ON), for
example.
[0161] In step S30, it is determined whether the present control of
air conditioning is pre-air conditioning or not. When the present
air conditioning control is determined not to be the pre-air
conditioning in step S30 (if NO), the operation proceeds to step
S31.
[0162] In step S31, it is determined whether the outside air
temperature Tam is in an extreme-low temperature range or not. For
example, it is determined whether an outside air temperature Tam
detected by an outside air temperature sensor 52 is lower than
-5.degree. C. or not. When the outside air temperature Tam is
determined to be lower than -5.degree. C. in step S31 (if YES), the
operation proceeds to step S32, and then the operation of the
engine EG (turning the engine ON) is selected. That is, a heater
core 36 for heating air using an engine coolant as a heat source is
selected as heating means for the interior of the vehicle.
[0163] As a result, when the engine EG is stopped, a request signal
for actuating the engine EG is output to the engine controller in
step S15 of FIG. 6. Then, the engine EG is actuated.
[0164] Subsequently, in step S33, a relative humidity RHW of the
surface of a windowpane is calculated, and it is determined whether
the possibility of fogging of the windowpane is high or not based
on the calculated relative humidity RHW of the windowpane surface.
In the present embodiment, it is determined whether or not the
relative humidity RHW is higher than a value (e.g., 110).
[0165] When the RHW is determined to be higher than 110 in step S33
(if YES), the possibility of fogging of the windowpane is
determined to be high, and the operation proceeds to step S34 where
the required number of revolutions of the engine EG, which is the
number of revolutions required for the engine EG, is set to a
relatively high value (e.g., in the present embodiment, 1500 rpm)
higher than a predetermined value. As a result, in step S15 shown
in FIG. 6, the operation of the engine at the high number of
revolutions of the engine is required of the engine controller.
[0166] When the negative determination is made in step S33 (if NO),
the operation proceeds to step S35. In step S35, it is determined
whether or not a vehicle interior preset temperature Tset set by a
vehicle interior temperature setting switch 60c of the operation
panel 60 is higher than a predetermined set temperature. In the
present embodiment, it is determined whether or not the Tset is
higher than 31.degree. C., for example.
[0167] When the Tset is determined to be higher than 31.degree. C.
in step S35 (if YES), the operation proceeds to step S34 described
above where the requested number of revolutions of the engine is
set to a high value. On the other hand, when the negative
determination is made in step S35 (if NO), the operation proceeds
to step S36.
[0168] In step S36, it is determined whether or not an engine
coolant temperature Tw is lower than a predetermined reference
value. In the present embodiment, it is determined whether or not
the engine coolant temperature Tw is lower than a target outlet air
temperature TAO, and whether or not a difference between the engine
coolant temperature Tw and the target outlet air temperature TAO is
larger than 10.degree. C.
[0169] When the engine coolant temperature Tw is determined to be
lower than the target outlet air temperature TAO, and when a
difference between the engine coolant temperature Tw and the target
outlet air temperature TAO is determined to be larger than
10.degree. C. (if YES), the operation proceeds to step S34
described above where the requested number of revolutions of the
engine is set to a relatively high value (e.g., 1500 rpm).
[0170] On the other hand, when the negative determination is made
in step S36 (if NO), the operation proceeds to step S37. In step
S37, the required number of revolutions of the engine is set to a
relative low value (e.g., in the present embodiment, 1000 rpm)
lower than the predetermined value. When the negative determination
is made in each of steps S33, S35 and S36 (if NO), the engine
coolant temperature Tw does not need to be increased quickly. By
setting the number of revolutions of the engine to the low value in
step S37, the fuel efficiency can be improved.
[0171] After selecting the required number of revolutions of the
engine in step S34 or S37, the operation of the PTC heater 37
(turning the PTC heater ON) is selected in step S38. As a result, a
control signal is output to the PTC heater 37 in step S17 shown in
FIG. 6, causing the PTC heater 37 to heat the air.
[0172] Subsequently, in step S39, a cooler cycle (cooling mode) is
selected as an operating mode of the refrigeration cycle. As a
result, the dehumidifying and heating operation is performed by
dehumidifying using the cooler cycle and heating using the heater
core 36 and the PTC heater 37.
[0173] When the outside air temperature Tam is determined to be
equal to or more than -5.degree. C. in step S31 (if NO), the
operation proceeds to step S40. In step S40, it is determined
whether or not an air outlet mode (automatic air outlet) determined
based on the TAO is the face mode. This is to determine the
necessity of heating.
[0174] When the air outlet mode is the face mode (if YES), the
heating is determined to be unnecessary, and then the operation
proceeds to step S41 where the cooler cycle (cooling mode) is
selected as the operating mode of the refrigeration cycle. On the
other hand, when the air outlet mode is not the face mode (if NO),
the heating is determined to be necessary, and then the operation
proceeds to step S46 and the following steps. Then, one cycle is
selected from among the HOT cycle, DRY_EVA cycle, and DRY_ALL cycle
based on the necessity of the dehumidification. That is, any one
mode can be selected from among the heating mode, the first
dehumidification mode, and the second dehumidification mode based
on the necessity of the dehumidification.
[0175] As mentioned above, the air outlet mode is determined based
on the TAO in step S9 of FIG. 6. Thus, when the determination in
step S40 is performed for the first time, the air outlet mode is
not determined yet in the automatic control. When the determination
in step S40 is first intended to be performed, step S40 and the
following steps (specifically, steps S40, S41, and S46 to S50) are
omitted, or the determination process of the step S40 or the like
is executed in a temporary air outlet mode (initialization of the
air outlet mode).
[0176] When the present air conditioning is determined to be the
pre-air conditioning in step S30 (if YES), the operation proceeds
to step S42. In step S42, it is determined whether or not the
outside air temperature Tam is lower than -5.degree. C., as in step
S31. When the outside air temperature Tam is determined to be lower
than -5.degree. C. (if YES), the operation of the PTC heater 37
(turning the PTC ON) is selected in step S43, while selecting stop
of the operation of the refrigeration cycle. Thus, the pre-air
conditioning (i.e., heating) is performed using the PTC heater
37.
[0177] When the negative determination is made in step S42 (if NO),
the operation proceeds to step S44 where it is determined whether
or not the air outlet mode is the face mode in the same way as that
in step S40. In the case of the face mode (if YES at S44), the
heating is determined to be unnecessary, and then the operation
proceeds to step S45 where the cooler cycle (cooling mode) is
selected. Further, in the case of any mode other than the face mode
(if NO at S44), the operation proceeds to step S46.
[0178] In step S46, it is determined whether or not there is a
possibility of fogging of the windowpane based on the relative
humidity RHW of the surface of the windowpane. In the present
embodiment, it is determined whether or not the RHW is higher than
100. When the RHW is higher than 100 (if YES), it is determined
that there is a possibility of fogging the windowpane, and then the
operation proceeds to S47.
[0179] In step S47, the degree of need (necessity) of the
dehumidification is determined on the evaporator blown-air
temperature Te. Based on the determination result, one mode is
selected from among the heating mode, first dehumidification mode,
and second dehumidification mode in any one of steps S48 to
S50.
[0180] Specifically, when the evaporator blown-air temperature Te
is high, the dehumidification is determined to be necessary. When
the necessity of the dehumidification is determined to be large,
the DRY_EVA cycle (first dehumidification mode) with the high
dehumidification capacity is selected in step S48. When the
evaporator blown-air temperature Te is low, the dehumidification is
determined to be unnecessary, and then the HOT cycle (heating mode)
without the dehumidification capacity with the high heating
capacity is selected in step S50. When the evaporator blown-air
temperature Te is moderate, the necessity of dehumidification is
determined to be small, and then the DRY_ALL cycle with the small
dehumidification capacity (second dehumidification mode) is
selected (step S49).
[0181] In the present embodiment, the degree of need of
dehumidification is determined based on the evaporator blown-air
temperature Te and the map shown in step S47 of FIG. 9. The
operating mode is selected using the map, so that the temperature
of the indoor evaporator 26 is controlled to about 2.degree. C.
[0182] On the other hand, when the RHW is determined to be equal to
or less than 100 in step S46 (if NO), it is determined that there
is no possibility of fogging of the windowpane (heating mode).
Then, the operation proceeds to step S50 where the HOT cycle
(heating mode) without the dehumidification capacity with the high
heating capacity is selected.
[0183] The air conditioner 1 for a vehicle of the present
embodiment is controlled as mentioned above, and is operated based
on the operating mode selected in the control step S6 in the
following way.
(a) Cooling Mode (COOL Cycle: see FIG. 1)
[0184] In the cooling mode, the air conditioning controller 50 sets
all electromagnetic valves in the non-energization state. Thus, the
electric three-way valve 13 connects the refrigerant outlet side of
the indoor condenser 12 to one of the refrigerant inlet and outlet
ports of the first three-way joint 15, so that the low-pressure
electromagnetic valve 17 is closed, the high-pressure
electromagnetic valve 20 is opened, the heat exchanger interruption
electromagnetic valve 21 is opened, and the dehumidification
electromagnetic valve 24 is closed.
[0185] Thus, as illustrated by the arrows in FIG. 1, the vapor
compression refrigeration cycle is constructed in which refrigerant
circulates through the compressor 11, the indoor condenser 12, the
electric three-way valve 13, the first three-way joint 15, the
outdoor heat exchanger 16, the second three-way joint 19, the
high-pressure electromagnetic valve 20, the second check valve 22,
the variable throttle mechanism 27b of the thermal expansion valve
27, the fourth three-way joint 25, the indoor evaporator 26, the
temperature sensing portion 27a of the thermal expansion valve 27,
the fifth three-way joint 28, the accumulator 29, and the
compressor 11 in that order.
[0186] In the refrigerant circuit in the cooling mode, the
refrigerant flowing from the electric three-way valve 13 to the
first three-way joint 15 does not flow out to the low-pressure
electromagnetic valve 17 side because the low-pressure
electromagnetic valve 17 is closed. The refrigerant flowing from
the outdoor heat exchanger 16 into the second three-way joint 19
does not flow out to the heat exchanger interruption
electromagnetic valve 21 because the dehumidification
electromagnetic valve 24 is closed. The refrigerant flowing from
the variable throttle mechanism 27b of the thermal expansion valve
27 does not flow out to the dehumidification electromagnetic valve
24 side because the valve 24 is closed. The refrigerant flowing
from the temperature sensing portion 27a of the thermal expansion
valve 27 into the fifth three-way joint 28 does not flow out to the
second check valve 22 by the action of the second check valve
22.
[0187] Thus, the refrigerant compressed by the compressor 11 is
cooled by exchanging heat with the air (cool air) having passed
through the indoor evaporator 26 in the indoor condenser 12.
Further, the refrigerant is cooled by exchanging heat with the
outside air in the outdoor evaporator 16, and then decompressed and
expanded by the thermal expansion valve 27. The low-pressure
refrigerant decompressed by the thermal expansion valve 27 flows
into the indoor evaporator 26, and absorbs heat from the air blown
from the blower 32, thus evaporating itself. Thus, the air passing
through the indoor evaporator 26 is cooled.
[0188] At this time, since the opening degree of the air mix door
38 is adjusted as mentioned above, a part (or all) of the air
cooled by the indoor evaporator 26 flows from the cool air bypass
passage 34 to the mixing space 35. And, a part (or all) of the air
cooled by the indoor evaporator 26 flows into the heating air
passage 33, and is then heated again while passing through the
heater core 36, the indoor condenser 12, and the PTC heater 37 to
flow into the mixing, space 35.
[0189] Thus, the airs are mixed in the mixing space 35 thereby to
adjust the temperature of the air blown off into the vehicle
interior to a desired temperature, so that the cooling operation
can be performed in the vehicle compartment. In the cooling mode,
the air conditioner has the higher dehumidification capacity of the
air, but hardly exhibits the heating capacity.
[0190] The refrigerant flowing from the indoor evaporator 26 flows
into the accumulator 29 via the temperature sensing portion 61a of
the thermal expansion valve 27. The refrigerant is separated by the
accumulator 29 into vapor and liquid phases, and the refrigerant in
the vapor phase is sucked into and compressed again by the
compressor 11.
(b) Heating Mode (HOT Cycle: see FIG. 2)
[0191] In the heating mode, the air conditioning controller 50 sets
the electric three-way valve 13, the high-pressure electromagnetic
valve 20, and the low-pressure electromagnetic valve 17 in the
energization state, and other electromagnetic valves 21 and 24 in
the non-energization state. Thus, the electric three-way valve 13
connects the refrigerant outlet side of the indoor condenser 12 to
the refrigerant inlet side of the fixed throttle 14, so that the
low-pressure electromagnetic valve 17 is opened, the high-pressure
electromagnetic valve 20 is closed, the heat exchanger interruption
electromagnetic valve 21 is opened, and the dehumidification
electromagnetic valve 24 is closed.
[0192] Thus, as illustrated by the arrows in FIG. 2, the vapor
compression refrigeration cycle is constructed in which refrigerant
circulates through the compressor 11, the indoor condenser 12, the
electric three-way valve 13, the fixed throttle 14, the third
three-way joint 23, the heat exchanger interruption electromagnetic
valve 21, the second three-way joint 19, the outdoor heat exchanger
16, the first three-way joint 15, the low-pressure electromagnetic
valve 17, the first check valve 18, the fifth three-way joint 28,
the accumulator 29, and the compressor 11 in that order.
[0193] In the refrigerant circuit in the heating mode, the
refrigerant flowing from the fixed throttle 14 to the third
three-way joint 23 does not flow out to the dehumidification
electromagnetic valve 24 side because the valve 24 is closed. The
refrigerant flowing from the heat exchanger interruption
electromagnetic valve 21 into the second three-way joint 19 does
not flow out to the high-pressure electromagnetic vale 20 because
the valve 20 is closed. The refrigerant flowing from the outdoor
heat exchanger 16 into the first three-way joint 15 does not flow
out to the electric three-way valve 13 because the electric
three-way valve 13 connects the refrigerant outlet side of the
indoor condenser 12 to the refrigerant inlet side of the fixed
throttle 14. The refrigerant flowing from the first check valve 18
into the fifth three-way joint 28 does not flow out to the thermal
expansion valve 27 because the dehumidification electromagnetic
valve 24 is closed.
[0194] The refrigerant compressed by the compressor 11 is cooled by
exchanging heat with the air blown from the blower 32 in the indoor
condenser 12. Thus, the air passing through the indoor condenser 12
is heated. At this time, the opening degree of the air mix door 38
is adjusted, so that the temperature of the air mixed in the mixing
space 35 and blown into the vehicle interior is adjusted to a
predetermined temperature, in the same way as in the cooling mode
thereby to enable heating operation in the vehicle interior. In the
heating mode, the air conditioner does not exhibit the
dehumidification capacity of the air.
[0195] The refrigerant flowing from the indoor condenser 12 is
decompressed by the fixed throttle 14 to flow into the outdoor heat
exchanger 16. The refrigerant flowing into the outdoor heat
exchanger 16 absorbs heat from air outside the vehicle compartment
blown from the blower fan 16a to evaporate itself. The refrigerant
flowing from the outdoor heat exchanger 16 flows into the
accumulator 29 via the low-pressure electromagnetic valve 17, the
first check valve 18, and the like. The refrigerant is separated by
the accumulator 29 into vapor and liquid phases, and the
refrigerant in the vapor phase is sucked into and compressed again
by the compressor 11.
(c) First Dehumidification Mode (DRY_EVA_Cycle: see FIG. 3)
[0196] In the first dehumidification mode, the air conditioning
controller 50 set the electric three-way valve 13, the low-pressure
electromagnetic valve 17, the heat exchanger interruption
electromagnetic valve 21, and the dehumidification electromagnetic
valve 24 in the energization state, and the high-pressure
electromagnetic valve 20 in the non-energization state. Thus, the
electric three-way valve 13 connects the refrigerant outlet side of
the indoor condenser 12 to the refrigerant inlet side of the fixed
throttle 14, so that the low-pressure electromagnetic valve 17 is
opened, the high-pressure electromagnetic valve 20 is opened, the
heat exchanger interruption electromagnetic valve 21 is closed, and
the dehumidification electromagnetic valve 24 is opened.
[0197] Thus, as illustrated by the arrows in FIG. 3, the vapor
compression refrigeration cycle is constructed in which refrigerant
circulates through the compressor 11, the indoor condenser 12, the
electric three-way valve 13, the fixed throttle 14, the third
three-way joint 23, the dehumidification electromagnetic valve 24,
the fourth three-way joint 25, the indoor evaporator 26, the
temperature sensing portion 27a of the thermal expansion valve 27,
the fifth three-way joint 28, the accumulator 29, and the
compressor 11 in that order.
[0198] In the refrigerant circuit in the first dehumidification
mode, the refrigerant flowing from the fixed throttle 14 to the
third three-way joint 23 does not flow out to the heat exchanger
interruption electromagnetic valve 21 because the valve 21 is
closed. The refrigerant flowing from the dehumidification
electromagnetic valve 24 into the fourth three-way joint 25 does
not flow out to the variable throttle mechanism 27b of the thermal
expansion valve 27 by the action of the second check valve 22. The
refrigerant flowing from the temperature sensing portion 27a of the
thermal expansion valve 27 to the fifth three-way joint 28 does not
flow out to the first check valve 18 by the action of the first
check valve 18.
[0199] Thus, the refrigerant compressed by the compressor 11 is
cooled by exchanging heat with the air (cool air) having passed
through the indoor evaporator 26 in the indoor condenser 12. Thus,
the air passing through the indoor condenser 12 is heated. The
refrigerant flowing from the indoor condenser 12 is decompressed by
the fixed throttle 14 to flow into the indoor evaporator 26.
[0200] The low-pressure refrigerant flowing into the indoor
evaporator 26 absorbs heat from the air blown from the blower 32 to
evaporate itself. Then, the air passing through the indoor
evaporator 26 is cooled and dehumidified. Thus, the air cooled and
dehumidified by the indoor evaporator 26 is heated again when
passing through the heater core 36, the indoor condenser 12, and
the PTC heater 37 to be blown from the mixing space 35 into the
vehicle interior. That is, dehumidification of the vehicle interior
can be performed. In the first dehumidification mode, the air
conditioner can exhibit the adequate dehumidification capacity of
the air, but has the small heating capacity.
[0201] The refrigerant flowing from the indoor evaporator 26 flows
into the accumulator 29 via the temperature sensing portion 61a of
the thermal expansion valve 27. The refrigerant is separated by the
accumulator 29 into vapor and liquid phases, and the refrigerant in
the vapor phase is sucked into and compressed again by the
compressor 11.
(d) Second Dehumidification Mode (DRY_ALL Cycle: see FIG. 4)
[0202] In the second dehumidification mode, the air conditioning
controller 50 sets the electric three-way valve 13, the
low-pressure electromagnetic valve 17, and the dehumidification
electromagnetic valve 24 in the energization state, and the other
electromagnetic valves 20 and 21 in the non-energization state.
Thus, the electric three-way valve 13 connects the refrigerant
outlet side of the indoor condenser 12 to the refrigerant inlet
side of the fixed throttle 14, so that the low-pressure
electromagnetic valve 17 is opened, the high-pressure
electromagnetic valve 20 is opened, the heat exchanger interruption
electromagnetic valve 21 is opened, and the dehumidification
electromagnetic valve 24 is opened.
[0203] Thus, as illustrated by the arrows in FIG. 4, the vapor
compression refrigeration cycle is constructed in the following
manner. The refrigerant circulates through the compressor 11, the
indoor condenser 12, the electric three-way valve 13, the fixed
throttle 14, the third three-way joint 23, the heat exchanger
interruption electromagnetic valve 21, the second three-way joint
19, the outdoor heat exchanger 16, the first three-way joint 15,
the low-pressure electromagnetic valve 17, the first check valve
18, the fifth three-way joint 28, the accumulator 29, and the
compressor 11 in that order. Further, the refrigerant circulates
through the compressor 11, the indoor condenser 12, the electric
three-way valve 13, the fixed throttle 14, the third three-way
joint 23, the dehumidification electromagnetic valve 24, the fourth
three-way joint 25, the indoor evaporator 26, the temperature
sensing portion 27a of the thermal expansion valve 27, the fifth
three-way joint 28, the accumulator 29, and the compressor 11 in
that order.
[0204] That is, in the second dehumidification mode, the
refrigerant flowing from the fixed throttle 14 into the third
three-way joint 23 flows out toward both the heat exchanger
interruption electromagnetic valve 21 and the dehumidification
electromagnetic valve 24. Both the refrigerant flowing from the
first check valve 18 into the fifth three-way joint 28 and the
refrigerant flowing from the temperature sensing portion 27a of the
thermal expansion valve 27 into the fifth three-way joint 28 are
merged into one flow at the fifth three-way joint 28, which then
flows out to the accumulator 29.
[0205] In the refrigerant circuit in the second dehumidification
mode, the refrigerant flowing from the outdoor heat exchanger 16
into the first three-way joint 15 does not flow out toward the
electric three-way valve 13 because the electric three-way valve 13
connects the refrigerant outlet side of the indoor condenser 12 to
the refrigerant inlet side of the fixed throttle 14. The
refrigerant flowing from the dehumidification electromagnetic valve
24 into the fourth three-way joint 25 does not flow out toward the
variable throttle mechanism 27b of the thermal expansion valve 27
by the action of the second check valve 22.
[0206] Thus, the refrigerant compressed by the compressor 11
exchanges heat with the air (cool air) having passed through the
indoor evaporator 26 in the indoor condenser 12. Thus, the air
passing through the indoor condenser 12 is heated. The refrigerant
flowing from the indoor condenser 12 is decompressed by the fixed
throttle 14, and then divided by the third three-way joint 23 to
flow into the outdoor heat exchanger 16 and the indoor evaporator
26.
[0207] The refrigerant flowing into the outdoor heat exchanger 16
absorbs heat from the air outside the vehicle compartment blown
from the blower fan 16a to evaporate itself. The refrigerant
flowing from the outdoor heat exchanger 16 flows into the fifth
three-way joint 28 via the low-pressure electromagnetic valve 17,
the first check valve 18, and the like. The low-pressure
refrigerant flowing into the indoor evaporator 26 absorbs heat from
the air blown from the blower 32 to evaporate itself. Thus, the air
passing through the indoor evaporator 26 is cooled and
dehumidified.
[0208] The air cooled and dehumidified by the indoor evaporator 26
is heated again while passing through the heater core 36, the
indoor condenser 12, and the PTC heater 37, and is blown from the
mixing space 35 into the vehicle interior. At this time, in the
second dehumidification mode, heat absorbed by the outdoor heat
exchanger 16 can be dissipated at the indoor condenser 12 as
compared to in the first dehumidification mode, so that the air can
be heated at higher temperature than in the first dehumidification
mode. That is, in the second dehumidification mode,
dehumidification and heating can be performed while exhibiting the
high heating capacity and dehumidification capacity.
[0209] The refrigerant flowing from the indoor evaporator 26 flows
into the fifth three-way joint 28 to be merged with the refrigerant
flowing from the outdoor heat exchanger 16, and then to flow into
the accumulator 29. The refrigerant is separated into vapor and
liquid phases by the accumulator 29. The vapor-phase refrigerant is
sucked into and compressed again by the compressor 11.
[0210] Next, the effects and advantages in the air conditioner for
a vehicle will be described.
[0211] (1) When the outside air temperature Tam is an extreme-low
temperature that is lower than -5.degree. C., even if the
refrigeration cycle 10 is operated in the HOT cycle (heating mode)
for heating the interior of the vehicle, the heating efficiency is
bad and the frost formation may be caused on the outdoor heat
exchanger 16 at an early stage after the start of the
operation.
[0212] When the outside air temperature Tam is the extreme-low
temperature, as shown in steps S31 and S32, the air conditioning
controller 50 does not select the HOT cycle (heating mode) as the
heating means for the vehicle interior, and selects the heater core
36 for heating using an engine coolant as a heat source. If the
engine EG is stopped, then the engine EG is activated (see step
S15).
[0213] Thus, even at the extreme-low outside air temperature Tam,
the adequate heating capacity can be ensured. This embodiment
performs the heating using the engine coolant as a heat source, so
that the exhaust gas from the engine can be sufficiently cleaned
using the existing engine exhaust emission control system as
compared to the case of using the combustion heater, and that the
high heating capacity can be obtained as compared to the case of
heating using only the electric heater, such as the PTC heater.
[0214] Also, in this case, because electricity can be generated by
the operation of the engine, it can compensate for the power
consumption of the electric heater.
[0215] (2) The air conditioning controller 50 operates the engine
EG when the outside air temperature Tam is the extreme-low
temperature, as in steps S31 to S34. Furthermore, when the
possibility of fogging of the windowpane is high, the air
conditioning controller 50 sets the number of revolutions of the
engine higher than that in the case where the possibility of
fogging of the windowpane is low.
[0216] Thus, the engine EG can be operated at the high number of
revolutions thereby to quickly increase the engine coolant
temperature Tw, thus rapidly increasing a blown air temperature.
Thus, the temperature of the windowpane can be increased soon,
thereby improving the antifogging properties.
[0217] (3) The air conditioning controller 50 operates the engine
EG when the outside air temperature Tam is the extreme-low
temperature, as in steps S31, S32, S34, and S35. Furthermore, when
the vehicle interior preset temperature Tset is higher than a
predetermined set temperature (for example, 31.degree. C.), the air
conditioning controller 50 sets the number of revolutions of the
engine higher than that in the case where the temperature Tset is
lower than the predetermined set temperature.
[0218] Thus, when the vehicle interior preset temperature Tset is
set to a very high temperature because of the passenger's desire
for quick strong heating, the required number of revolutions of the
engine can be set to a high value so as to rapidly increase the
blown air temperature. As a result, the hot feeling of the
passenger can be quickly improved in response to the passenger's
desire.
[0219] (4) The air conditioning controller 50 operates the engine
EG when the outside air temperature Tam is the extreme-low
temperature, as in steps S31, S32, S34, and S36. Furthermore, when
the engine coolant temperature Tw is lower than a target outlet air
temperature TAO and when a difference in temperature therebetween
is larger than a predetermined temperature, the number of
revolutions of the engine is set high as compared to a case other
than the above case.
[0220] Thus, when the engine coolant temperature Tw is too low with
respect to the target temperature to make the blown air temperature
too low, the required number of revolutions of the engine is set to
a high value, and thereby it can rapidly increase the blown air
temperature, thus quickly improving the warm feeling of the
passenger.
[0221] (5) The air conditioning controller 50 operates the engine
EG as well as the PTC heater 37 when the outside air temperature
Tam is the extreme-low temperature, as in steps S32, and S38. The
air conditioner performs both heating by use of the engine coolant
and by the PTC heater 37, so that the blown air temperature can be
sufficiently increased by the PTC heater 37 even when the engine
coolant temperature Ts is low. Thus, the heating capacity can be
surely ensured.
[0222] (6) The air conditioning controller 50 operates the engine
EG, and sets the refrigeration cycle 10 in the cooler cycle
(cooling mode) when the outside air temperature Tam is the
extreme-low temperature, as in steps S32 and S39. When the fogging
of the windowpane tends to be caused due to the extreme-low outside
air temperature, the strong dehumidification can be carried out in
the cooler cycle, thus improving the antifogging properties.
Second Embodiment
[0223] In the above first embodiment, heating using the heater core
36 (i.e., heating using the engine coolant as a heat source) is
selected at the extreme-low outside air temperature lower than
-5.degree. C. In contrast, in a second embodiment, as shown in FIG.
10, heating by the heater core 36 (i.e., heating using the engine
coolant as a heat source) is selected when the vehicle interior
preset temperature Tset is set to a very high temperature higher
than 31.degree. C.
[0224] That is, when the heat pump cycle is selected while the
vehicle interior preset temperature Tset is set to a very high
temperature, the operating rate of the heat pump cycle becomes
high, thereby rapidly causing the frost formation on the outdoor
heat exchanger 16. The frost formation on the outdoor heat
exchanger 16 reduces the heat exchange efficiency of the outdoor
heat exchanger 16, degrading the heating capacity.
[0225] In the present embodiment, when the vehicle interior preset
temperature Tset is set to a very high temperature, the engine is
turned ON to heat the heater core 36, thus ensuring the sufficient
heating capacity.
[0226] Now, the process of step S6 in the present embodiment will
be described in more detail below. FIG. 10 is a flowchart showing a
main part of the process of step S6. The control process shown in
the flowchart of FIG. 10 is performed when the air conditioner
switch 60a and the automatic switch 60b are turned on (ON), or the
like.
[0227] In step S60, it is determined whether or not the present
operating mode is the heat pump cycle (heating mode, or the first
or second dehumidification mode). When the present operating mode
is the heat pump cycle (if YES), the operation proceeds to step
S61.
[0228] In step S61, it is determined whether or not the vehicle
interior preset temperature Tset set by the vehicle interior
temperature setting switch 60c of the operation panel 60 is higher
than a predetermined set temperature. For example, it is determined
whether or not the temperature Tset is higher than 31.degree.
C.
[0229] When the Tset is determined to be higher than 31.degree. C.
in step S61 (if YES), the operation proceeds to step S62 where the
operation of the engine EG (turning the engine ON) is selected.
That is, when the vehicle interior preset temperature Tset is too
high, it is determined that the passenger desires the strong
heating, and then the heating by use of the heater core 36 (i.e.,
heating using the engine coolant as a heat source) is selected.
[0230] Subsequently, in step S63, it is determined whether or not
the blown air at the target outlet air temperature TAO can be made
using the engine coolant. In the present embodiment, when the
engine coolant temperature Tw is equal to or more than a target
temperature for the indoor condenser (i.e., target indoor condenser
temperature, the blown air at the target outlet air temperature TAO
is determined to be capable of being made using the engine coolant
(YES determination), and the operation proceeds to step S64 where
the cooler cycle (cooling mode) is selected. As a result, the
dehumidification operation is performed in the cooler cycle
(cooling mode), while the dehumidifying and heating operation is
performed for heating by use of the heater core 36.
[0231] Further, the target indoor condenser temperature is
basically the same as the target heat exchanger temperature for
heating described above. In some cases, the target indoor condenser
temperature is a value obtained by slightly amending the target
heat exchanger temperature for heating.
[0232] On the other hand, when the negative determination is made
in step S61 or S63 (if NO), the operation proceeds to steps S65 to
S69 to select the heat pump cycle. The steps S65 to S69 are the
same as steps S46 to S50 of the first embodiment.
[0233] The processes in step S65 to S69 appropriately select one
from among the HOT cycle, DRY_EVA cycle, and DRY_ALL cycle (heating
mode, first dehumidification mode, and second dehumidification
mode) according to the possibility of fogging of the windowpane and
the necessity of dehumidification.
[0234] According to the present embodiment, when the vehicle
interior preset temperature Tset is higher than the predetermined
set temperature (for example, 31.degree. C.) with the heat pump
cycle set, the air conditioning controller 50 selects the engine
ON, and then selects heating by the heater core 36 (i.e., heating
using the engine coolant as a heat source), as in steps S61 and
S62.
[0235] Thus, even when the vehicle interior preset temperature Tset
is set to a very high one, the air conditioner can ensure the
sufficient heating capacity.
Third Embodiment
[0236] In the above first embodiment, the heating using the heater
core 36 (i.e., heating using the engine coolant as a heat source),
and the dehumidification using the cooler cycle are performed at
the extreme-low outside air temperature lower than -5.degree. C.
However, in a third embodiment, as shown in FIG. 11, heating is
performed using both of the heater core 36 (i.e., heating using the
engine coolant as a heat source) and the heat pump cycle at a low
outside air temperature lower than -2.degree. C.
[0237] Now, the process in step S6 of the present embodiment will
be described in detail below. FIG. 11 is a flowchart showing a main
part of the process in step S6. The control process shown in the
flowchart of FIG. 11 is carried out when the air conditioner switch
60a and the automatic switch 60b are turned on (ON), or the
like.
[0238] In step S70, it is determined whether the present air
conditioning control is pre-air conditioning or not. When the
present air conditioning control is determined not to be the
pre-air conditioning in step S70 (if NO), the operation proceeds to
step S71. In step S71, it is determined whether or not the outside
air temperature Tam is in a low temperature range. For example, it
is determined whether or not the outside air temperature Tam
detected by the outside air sensor 52 is lower than -2.degree.
C.
[0239] When the outside air temperature Tam is determined to be
lower than -2.degree. C. in step S71 (if YES), the operation
proceeds to step S72 where it is determined whether or not the
engine coolant temperature Tw is higher than the predetermined
temperature (in the present embodiment, the target outlet air
temperature TAO). When the engine coolant temperature Tw is
determined to be higher than the target outlet air temperature TAO
(if YES), the operation proceeds to step S73 where the cooler cycle
(cooling mode) is selected. Thus, if the operation of the heat pump
cycle has continued until this time, then the operation of the heat
pump cycle is stopped.
[0240] When the engine coolant temperature Tw is determined to be
equal to or less than the target outlet air temperature TAO in step
S72 (if NO), the operation proceeds to step S74 where the operation
of the engine EG (engine ON) is selected. That is, the heater core
36 for heating air using the engine coolant as a heat source is
selected as heating means for the vehicle interior.
[0241] As a result, if the engine EG is stopped, then a request
signal for actuating the engine EG is output to the engine
controller in step S15 of FIG. 6 to actuate the engine EG.
[0242] In step S75, it is determined whether or not the vehicle
interior preset temperature Tset set by the vehicle interior
temperature setting switch 60c of the operation panel 60 is higher
than the predetermined set temperature. For example, it is
determined whether or not the Tset is higher than 31.degree. C.
[0243] When the Tset is determined to be higher than 31.degree. C.
in step S75 (if YES), the operation proceeds to step S76 where the
required number of revolutions of the engine is set to a relatively
high one (e.g., in the present embodiment, 1500 rpm). As a result,
the operation of the engine at the high number of revolutions of
the engine is required of the engine controller in step S15 shown
in FIG. 6. On the other hand, when the negative determination is
made in step S75 (if NO), the operation proceeds to step S77.
[0244] In step S77, it is determined whether or not the engine
coolant temperature Tw is lower than a predetermined reference
value. In the present embodiment, it is determined whether or not
the engine coolant temperature Tw is lower than the target outlet
air temperature TAO, and whether or not a difference in temperature
therebetween is larger than 10.degree. C.
[0245] When the engine coolant temperature Tw is determined to be
lower than the target outlet air temperature TAO, and the
difference in temperature therebetween is larger than 10.degree. C.
(if YES), the operation proceeds to step S76 described above where
the required number of revolutions of the engine is set to a high
value.
[0246] When the negative determination is made in step S77 (if NO),
the operation proceeds to step S78. In step S78, the required
number of revolutions of the engine is set to a relatively low
value (e.g., 1000 rpm in the present embodiment). When the negative
determination is made both in steps S75 and S77, the engine coolant
temperature Tw does not need to be quickly increased. By setting
the number of revolutions of the engine low, as in step S78, the
fuel efficiency can be improved.
[0247] After the required number of revolutions of the engine is
selected in steps S76 and S78, the operation proceeds to step S79
where it is determined whether the air outlet mode determined based
on the TAO is the face mode or not. This is to determine the
necessity of heating.
[0248] When the air outlet mode is determined to be the face mode
(if YES), the heating is determined to be unnecessary, and then the
operation proceeds to step S80 where the cooler cycle (cooling
mode) is selected. On the other hand, when the air outlet mode is
determined not to be the face mode (if NO), the heating is
determined to be necessary, and then the operation proceeds to
steps S85 to S89 where one cycle is selected from among the HOT
cycle, DRY_EVA cycle, and DRY_ALL cycle (i.e., heating mode, first
dehumidification mode, and second dehumidification mode) according
to the possibility of fogging of the windowpane and the necessity
of dehumidification. The processes of steps S85 to S89 are the same
as those of steps S46 to S50 in the first embodiment.
[0249] When the negative determination is made in step S71 because
the outside air temperature Tam is higher than -2.degree. C. (if
NO), the operation proceeds to step S79 described above and the
following steps.
[0250] When the present air conditioning control is determined to
be the pre-air conditioning in step S70 (if YES), the operation
proceeds to step S81. In step S81, it is determined whether or not
the outside air temperature Tam is in the extreme-low temperature
range. For example, it is determined whether or not the outside air
temperature Tam detected by the outside air sensor 52 is lower than
-5.degree. C. When the outside air temperature Tam is determined to
be lower than -5.degree. C. (if YES), the operation proceeds to
step S82 where the operation of the PTC heater 37 (PTC ON) is
selected while the stop of the operation of the refrigeration cycle
is selected.
[0251] As a result, a control signal is output to the PTC heater 37
in step S17 shown in FIG. 6 thereby to heat the air by the PTC
heater 37. Thus, the pre-air conditioning (heating) is performed
using the PTC heater 37.
[0252] When the negative determination is made in step S81 (if NO),
the operation proceeds to step S83 where it is determined whether
or not the air outlet mode is the face mode, as in step S79. When
the air outlet mode is determined to be the face mode (if YES), the
heating is determined to be unnecessary, and the operation proceeds
to step S84 where the cooler cycle (cooling mode) is selected. When
the air outlet mode is determined to be one other than the face
mode (If NO), the operation proceeds to step S85.
[0253] In step S85, the possibility of fogging of the windowpane is
determined based on the relative humidity RHW of the surface of the
windowpane. In the present embodiment, it is determined whether or
not the RHW is higher than a value (e.g., 100). When the RHW is
higher than 100 (if YES), it is determined that there is
possibility of fogging of the windowpane, and then the operation
proceeds to step S86.
[0254] In step S86, the degree of need of dehumidification is
determined based on the evaporator outlet air temperature Te.
According to the determination result, one cycle is selected from
among the HOT cycle, DRY_EVA cycle, and DRY_ALL cycle (heating
mode, first dehumidification mode, and second dehumidification
mode) in any one of steps S87 to S89.
[0255] According to the present embodiment, when the outside air
temperature Tam is a low temperature, for example, lower than
-2.degree. C., the air conditioning controller 50 selects the
heating using the heater core 36 (i.e., heating using the engine
coolant as a heat source) by selecting the engine ON, while
selecting the heat pump cycle, as in steps S71, S74, and S87 to
S89.
[0256] Thus, the air conditioner can ensure the sufficient heating
capacity using the engine coolant, and also can obtain a quick
effect of heating using the heat pump cycle which has a rapid
increase in temperature of blown air.
[0257] Like in step S72 and S73, when the engine coolant
temperature Tw is higher than the predetermined temperature at a
low outside air temperature Tam lower than -2.degree. C., the air
conditioning controller 50 selects the cooler cycle (cooling mode).
The air conditioner can improve the dehumidification capacity even
under an atmosphere at the low outside air temperature which tends
to cause fogging of the windowpane, thus improving the antifogging
properties.
Fourth Embodiment
[0258] In the above first embodiment, the engine ON is selected at
the same time as when switching is performed from the heat pump
cycle to the cooler cycle. In a fourth embodiment, as shown in FIG.
12, the engine ON is previously selected to heat an engine coolant
before switching is performed from the heat pump cycle to the
cooler cycle.
[0259] Now, the process in step S6 of the present embodiment will
be described in more detail below. FIG. 12 is a flowchart showing a
main part of the process in step S6. The control process shown in
the flowchart of FIG. 12 is carried out when the air conditioner
switch 60a and the automatic switch 60b are turned on (ON), or the
like:
[0260] In step S90, it is determined whether or not the outside air
temperature Tam is in the extreme-low temperature range. In the
present embodiment, it is determined whether or not the outside air
temperature Tam detected by the outside air sensor 52 is lower than
a first predetermined temperature T1 (e.g., -5.degree. C.). When
the outside air temperature Tam is determined to be equal to or
more than the first predetermined temperature T1 (e.g., -5.degree.
C.) in step S90 (if NO), the operation proceeds to steps S91 to
S105. The processes in steps S91 to S105 are the same as those in
steps S71 to S80 and S85 to S89 of the third embodiment, and the
detail explanation thereof is omitted.
[0261] When the outside air temperature Tam is determined to be
lower than the first predetermined temperature T1 (e.g., -5.degree.
C.) in step S90 (if YES), the operation proceeds to step S106 where
the operation of the engine EG (engine ON) is selected. That is,
the heater core 36 for heating the air using the engine coolant as
a heat source is selected as heating means for the vehicle
interior.
[0262] As a result, if the engine EG is stopped, then a request
signal for requesting the engine controller to start the engine EG
is output to the engine controller in step S15 shown in FIG. 6, so
that the engine EG is actuated.
[0263] Subsequently, in step S107, it is determined whether or not
the vehicle interior preset temperature Tset set by the vehicle
interior temperature setting switch 60c of the operation panel 60
is higher than the predetermined set temperature. In the present
embodiment, it is determined whether or not the Tset is higher than
31.degree. C.
[0264] When the Tset is determined to be higher than 31.degree. C.
in step S107 (if YES), the operation proceeds to step S110 where
the required number of revolutions of the engine is set to a
relatively high value (e.g., in the present embodiment, 1500 rpm).
As a result, the operation of the engine at the high number of
revolutions is required of the engine controller in step S15 shown
in FIG. 6.
[0265] On the other hand, when the negative determination is made
in step S107 (if NO), the operation proceeds to step S108. In step
S108, it is determined whether or not the engine coolant
temperature Tw is lower than a predetermined reference value. In
the present embodiment, it is determined whether or not the engine
coolant temperature Tw is lower than the target outlet air
temperature TAO, and whether or not a difference in temperature
therebetween is larger than 10.degree. C.
[0266] When the engine coolant temperature Tw is lower than the
target outlet air temperature TAO, and a difference in temperature
therebetween is larger than 10.degree. C. (if YES), the operation
proceeds to step S110 described above. In step S110, the required
number of revolutions of the engine is set to a high value.
[0267] When the negative determination is made in step S108 (if
NO), the operation proceeds to step S109. In step S109, the
required number of revolutions of the engine is set to a relatively
low value (e.g., 1000 rpm in the present embodiment).
[0268] When the negative determination is made in each of steps
S107 and S108 (if NO), the engine coolant temperature Tw does not
need to be quickly increased, so that the number of revolutions of
the engine is set low, as in step S109, to enable improvement of
the fuel efficiency.
[0269] After selecting the required number of revolutions of the
engine in step S109 or S110, the cooler cycle (cooling mode) is
selected in step S111.
[0270] According to the present embodiment, when the outside air
temperature Tam is higher than a second predetermined temperature
T2 (-2.degree. C.), that is, when the efficiency of the heat pump
cycle is good and frost is hardly formed, the air conditioning
controller 50 selects the heat pump cycle without selecting the
engine ON, as in steps S91, and S103 to S105. Thus, heating can be
performed with low noise without any exhaust gas as compared to the
case of selecting the engine ON.
[0271] The air conditioning controller 50 selects the heat pump
cycle as well as the engine ON, as in steps S90, S91, S94, and S103
to S105, when the outside air temperature Tam is a low temperature
higher than -5.degree. C. (first predetermined temperature T1) and
lower than -2.degree. C. (second predetermined temperature T2),
that is, when the efficiency of the heat pump cycle is not good,
but frost is hardly formed for a short time.
[0272] With this arrangement, the air conditioner can obtain the
quick effect of heating by use of the heat pump cycle in which the
blown air temperature is quickly increased, and can also ensure a
heating source for heating by previously heating the engine coolant
in preparation for the case where the outside air temperature Tam
decreases to below -5.degree. C. (first predetermined temperature
T1) and the cooler cycle is selected. Thus, the heating can be
continued without being interrupted even when switching is
performed from the heat pump cycle to the cooler cycle, so that the
air conditioner can have improved practical utility.
[0273] In this case, because the operation of the engine can
generate electricity, it can compensate for power consumption of
the heat pump cycle.
[0274] After the engine coolant is sufficiently heated by the
operation of the engine, the heating capacity can be ensured even
when the operating rate of the heat pump cycle is reduced. Thus,
the air conditioner can ensure the heating capacity, while reducing
the operating rate of the heat pump cycle, thereby preventing the
frost formation.
[0275] The air conditioning controller 50 selects the engine ON,
and also selects the heating by use of the heater core 36 (i.e.,
heating using the engine coolant as a heat source), as in steps S90
and S106, when the outside air temperature Tam is an extreme-low
temperature lower than -5.degree. C. (first predetermined
temperature T1), that is, when the use of the heat pump cycle has
problems of reduction of the efficiency of the cycle, and of the
frost formation.
[0276] Thus, the sufficient heating capacity can be ensured by the
engine coolant, and the exhaust gas from the engine can be
sufficiently cleaned using the existing engine exhaust emission
control system.
Fifth Embodiment
[0277] The following will describe in detail the process in step
S11, that is, the way to determine the number of revolutions of the
compressor 11 according to a fifth embodiment.
[0278] The vapor compression refrigeration cycle is adapted to
determine the lack of refrigerant when the refrigerant pressure
falls below a predetermined pressure (e.g., a lower limit of
pressure) and then to stop the operation of the compressor 11. If
in this refrigeration cycle, the predetermined pressure (e.g.,
lower limit of pressure) in the heat pump cycle is set the same as
that in the cooler cycle, the following practical problems will be
caused.
[0279] That is, the heat pump cycle tends to decrease the
refrigerant pressure when the outside air temperature Tam becomes a
low temperature. By setting the predetermined pressure (e.g., lower
limit of pressure) using a refrigerant pressure in the cooler cycle
as the reference, the following problems will be caused. That is,
when the outside air temperature Tam becomes low in the heat pump
cycle, the refrigerant pressure falls below the predetermined
pressure (e.g., lower limit of pressure), and thereby it would stop
the operation of the compressor 11, although the refrigerant is not
lacking. In short, at the low outside air temperature, the heat
pump cycle cannot be operated, thereby resulting in a narrow
operational range of the heat pump cycle. For example, the
operational range is a range of the outside air temperature Tam, in
which heating by the heat pump cycle can be performed.
[0280] When the predetermined pressure (e.g., lower limit of
pressure) is set high as a measure for this, the detection of lack
of refrigerant in the cooler cycle becomes inaccurate.
[0281] In the present embodiment, the predetermined pressure (e.g.,
lower limit of pressure) is set low in the heat pump cycle, as
compared to that in the cooler cycle, so that the operational range
of the heat pump cycle (or range of the outside air temperature Tam
that enables heating by use of the heat pump cycle) is expanded
toward the low outside air temperature side, while the lack of
refrigerant is detected in the cooler cycle with high accuracy.
[0282] FIG. 13A is a flowchart showing a main part of the process
in step S11. The control process shown in the flowchart of FIG. 13A
is carried out when the automatic switch 60b is turned on (ON), or
the like.
[0283] In step S120, an amount of change in number of revolutions
.DELTA.fC of the compressor with respect to the previous number of
revolutions of the compressor fCn-1 is determined using a basic
determination way in the above-mentioned cooler cycle (cooling
mode). FIG. 13B shows an example of the rule of the fuzzy theory
for determining the amount of change in number of revolutions
.DELTA.fC, based on a temperature deviation Tn and a change rate
PDOT.
[0284] In step S121, an amount of change in number of revolutions
.DELTA.fH of the compressor with respect to the previous number of
revolutions of the compressor fHn-1 is determined using a basic
determination way in the above-mentioned heat pump cycle (heating
mode). FIG. 13C shows an example of the rule of the fuzzy theory
for determining the amount of change in number of revolutions
.DELTA.fH, based on a pressure deviation Pn and a change rate
PDOT.
[0285] Then, in step S122, it is determined whether or not the
cooler cycle is selected. When the cooler cycle is determined to be
selected (if YES), the operation proceeds to step S123 where the
amount of change in number of revolutions .DELTA.fC in the cooling
mode is substituted into the amount of change in number of
revolutions .DELTA.f.
[0286] When the cooler cycle is determined to be selected in step
S122, that is, when the heat pump cycle is determined to be
selected (if NO), the operation proceeds to step S124 where the
amount of change in number of revolutions .DELTA.fH in the heating
mode is substituted into the amount of change in number of
revolutions .DELTA.f.
[0287] Then, in step S125, the present temporary number of
revolutions of the compressor (f(TEMP)) is determined using the
previous number of revolutions of the compressor (fn-1) and the
amount of change in number of revolutions of the compressor
.DELTA.f (i.e., f (TEMP)=fn-1+.DELTA.f).
[0288] Then, in step S126, it is determined whether or not the
cooler cycle is selected. When the cooler cycle is determined to be
selected (if YES), the operation proceeds to step S127 where the on
or off (ON or OFF) of the compressor 11 is determined based on the
refrigerant pressure. In the present embodiment, the on or off (ON
or OFF) of the compressor 11 is determined based on the discharge
refrigerant pressure Pd of the compressor 11 detected by the
discharge pressure sensor 55 and the map shown in the process of
step S127 of FIG. 13A. Specifically, when the discharge refrigerant
pressure Pd is equal to or less than a predetermined pressure (0.2
MPa in the present embodiment), the refrigerant is determined to be
lacking, and the compressor 11 is determined to be turned off
(OFF): When the discharge refrigerant pressure Pd is equal to or
more than 2.8 MPa, it is determined that the amount of refrigerant
is excessive, or the state of the refrigeration cycle 10 is
abnormal, and then the compressor 11 is determined to be turned off
(OFF). In cases other than the above case, the compressor 11 is
determined to be turned on (ON). The map shown in the process of
step S127 of FIG. 13A has hysteresis set for preventing control
hunting.
[0289] When the compressor 11 is determined to be turned on (ON),
the operation proceeds to step S128 where the maximum number of
revolutions of the compressor is set to 10000 rpm (f(MAX)=10000
rpm). When the compressor 11 is determined to be turned off (OFF),
the operation proceeds to step S129 where the maximum number of
revolutions of the compressor is set to 0 rpm (f(MAX)=0 rpm).
[0290] Subsequently, in step S133, the final decision of the
present number of revolutions of the compressor (fn) is performed.
In the present embodiment, a smaller one of the present temporary
number of revolutions of the compressor (f(TEMP)) determined in
step S125 and the maximum number of revolutions of the compressor
(f(MAX)) determined in step S128 or S129 is defined as the present
number of revolutions of the compressor (fn=MIN [f(TEMP), f(MAX)]),
in step S133.
[0291] When a cycle other than the cooler cycle is determined to be
selected in step S126 (if NO), that is, when the heat pump cycle is
selected, the operation proceeds to step S130 where the on or off
(ON or OFF) of the compressor 11 is determined based on the
refrigerant pressure.
[0292] In the present embodiment, the on or off (ON or OFF) of the
compressor 11 is determined based on the discharge refrigerant
pressure Pd of the compressor 11 detected by the discharge pressure
sensor 55 and the map shown in the process of step S130 of FIG.
13A.
[0293] When the compressor 11 is determined to be turned on (ON),
the operation proceeds to step S131 where the maximum number of
revolutions of the compressor is set to 10000 rpm (i.e.,
f(MAX)=10000 rpm). When the compressor 11 is determined to be
turned off (OFF), the operation proceeds to step S132 where the
maximum number of revolutions of the compressor is set to 0 rpm
(f(MAX)=0 rpm). Subsequently, the operation proceeds to step S133
where the present number of revolutions of the compressor fn is
last determined similarly to above.
[0294] By comparison between the map shown in step S130 and the map
shown in step S127, when selecting the heat pump cycle, the turning
on (ON) of the compressor 11 can be allowed at a discharge
refrigerant pressure Pd lower than that when selecting the cooler
cycle. Thus, the outside air temperature Tam at which the heat pump
cycle can be operated can be set low as compared to that in the
cooler cycle.
[0295] As the lower limit of pressure (predetermined pressure) of
the discharge refrigerant pressure Pd for allowing the turning on
(ON) of the compressor 11, is used about a value of pressure (e.g.,
0.1 MPa in the present embodiment) at which the compressor 11 is
turned on (OFF) with the amount of refrigerant of about zero, which
is desirable for the purpose of protecting a cycle component.
[0296] According to the present embodiment, as in step S130 and
S127, in the heat pump cycle, the air conditioning controller 50
makes the lower limit of pressure (predetermined pressure) of the
discharge refrigerant pressure Pd for allowing the compressor 11 to
be turned on lower than that in the cooler cycle. The range of
outside air temperature Tam in which the heat pump cycle is
operational can be expanded toward the low outside air temperature
side as compared to that in the cooler cycle. Thus, the range of
outside air temperature which enables the heating by the heat pump
cycle can be expanded.
[0297] Like in step S130, the lower limit of pressure
(predetermined pressure) of the discharge refrigerant pressure Pd
for allowing the turning ON of the compressor 11 is set to about a
value of pressure (e.g., 0.1 MPa in the present embodiment) at
which the compressor 11 is turned off (OFF) with the amount of
refrigerant of about zero. Thus, when the refrigerant is almost
lost, the abnormal state of the air conditioner can be detected by
both the heat pump cycle and cooler cycle.
[0298] Further, in the cooler cycle, the lower limit of pressure
(predetermined pressure) of the discharge refrigerant pressure Pd
for allowing the turning on (ON) of the compressor 11 is set to a
slightly higher value (e.g., 0.2 MPa in the present embodiment)
than that in the heat pump cycle, so that the lack of refrigerant
in the cooler cycle can be detected with high accuracy.
Sixth Embodiment
[0299] In the first embodiment, when the heating is performed by
the heater core 36 (i.e., heating using the engine coolant as a
heat source), the number of revolutions of the engine is adjusted
such that the engine coolant temperature Tw gets close to the TAO.
In a sixth embodiment, as shown in FIG. 14, in using both of the
heating by the heater core 36 (i.e., heating by the engine coolant
as the heat source) and the heating by the PTC heater 37, the
engine coolant temperature Tw is made lower than the TAO.
[0300] That is, when the engine coolant temperature Tw gets close
to the TAO regardless of the operation or stop of the PTC heater
37, the heating capacity becomes excessive in operation of the PTC
heater 37, thereby resulting in a practical problem from the
viewpoint of fuel consumption saving.
[0301] In the present embodiment, when the PTC heater 37 is
operated, the engine coolant temperature Tw is decreased as
compared to when the PTC heater 37 is stopped, so that it can
prevent the heating capacity from becoming excessive, thereby
achieving the fuel consumption saving.
[0302] Now, the process in step S6 of the present embodiment will
be described in more detail below. FIG. 14 is a flowchart showing a
main part of the process in step S6. The control process shown in
the flowchart of FIG. 14 is carried out when the air conditioner
switch 60a and the automatic switch 60b are turned on (ON), or the
like.
[0303] In step S140, it is determined whether the air outlet mode
determined based on the TAO is the face mode or not. This is to
determine the necessity of heating.
[0304] When the air outlet mode is determined to be the face mode
(if YES), the heating is determined to be unnecessary, and then the
operation proceeds to step S156 where the cooler cycle (cooling
mode) is selected. When the air outlet mode is determined not to be
the face mode (if NO), the heating is determined to be necessary,
and then the operation proceeds to step S141.
[0305] In step S141, it is determined whether or not the outside
air temperature Tam is in an extreme-low temperature range. In the
present embodiment, it is determined whether or not the outside air
temperature Tam detected by the outside air sensor 52 is lower than
-5.degree. C. When the outside air temperature Tam is determined to
be lower than -5.degree. C. (if YES), the operation proceeds to
step S142 where it is determined whether a remaining battery level
is sufficient or not.
[0306] In the present embodiment, when the remaining battery level
is larger than a value provided by multiplying the air conditioning
interference level by a safety factor of 1.2 (i.e., air
conditioning interference level.times.1.2) (if YES), the remaining
battery level is determined to be very sufficient, and then the
operation proceeds to step S143.
[0307] The term "air conditioning interference level" as used
herein means a small remaining battery level that will interfere
with air conditioning. In the present embodiment, the air
conditioning interference level is previously set based on
specifications of a vehicle or the like. When the remaining battery
level reaches the air conditioning interference level, the power
for air conditioning is reduced at the time of acceleration of the
vehicle or the like because more power in such a time is required
for vehicle traveling, thereby interfering with the air
conditioning.
[0308] Subsequently, in step S143, the operation of the PTC heater
37 (PTC ON) is selected. As a result, a control signal is output to
the PTC heater 37 in step S17 shown in FIG. 6, so that the PTC
heater 37 heats the air. Thus, the heating is performed using the
PTC heater 37.
[0309] Subsequently, in step S144, a target coolant temperature
correction amount fBLW to be used in the following step S145 is
determined. In the present embodiment, the target coolant
temperature correction amount fBLW is determined based on a blower
motor voltage of the blower 32 (that is, the amount of air from the
blower 32), and the map shown in step S144 of FIG. 14. Thus, as the
amount of air from the blower 32 becomes small, the target coolant
temperature correction amount fBLW is made large in the negative
direction (i.e., minus direction).
[0310] Subsequently, in step S145, the target coolant temperature,
which is a target temperature of the engine coolant temperature Tw,
is determined based on the TAO and the target coolant temperature
correction amount fBLW determined in step S144. In the present
embodiment, the target coolant temperature is obtained by
correcting the TAO only by the target coolant temperature
correction amount fBLW (target coolant temperature=TAO+fBLW). In
the present embodiment, the smaller the amount of air blown from
the blower 32, the lower the target coolant temperature is than the
TAO. As a result, the operating rate of the engine EG is reduced
thereby to achieve the fuel consumption saving.
[0311] When the remaining battery level is determined not to be
sufficient in step S142 (if NO), the PTC heater 37 cannot be
operated. Then, the operation proceeds to step S146 where the
target coolant temperature is set high. In the present embodiment,
the target coolant temperature is set higher than the TAO only by
1.degree. C. (target coolant temperature=TAO+1.degree. C.).
[0312] After the target coolant temperature is determined in steps
S145 or S146, the operation proceeds to step S147 where it is
determined whether the present air conditioning control is pre-air
conditioning or not. When the present air conditioning control is
determined not to be the pre-air conditioning in step S147 (if NO),
the operation proceeds to step S148.
[0313] In step S148, it is determined whether or not the engine
coolant temperature Tw is higher than the target coolant
temperature. When the engine coolant temperature Tw is determined
to be lower than the target coolant temperature in step S148 (if
NO); the operation proceeds to step S149 so as to increase the
engine coolant temperature Tw up to the target coolant temperature,
where the operation of the engine EG (of turning on the engine) is
selected. When the operation of the engine EG is already operated
(engine is turned ON) in step S149, a request for increasing the
number of revolutions of the engine EG (engine revolution number UP
request) may be selected.
[0314] Subsequently, the operation proceeds to step S150 where the
stop of the compressor 11 is decided. Thus, the refrigeration cycle
10 is stopped, and the heating is performed by the heater core 36
and the PTC heater 37.
[0315] On the other hand, when the engine coolant temperature Tw is
determined to be higher than the target coolant temperature in step
S148 (if YES), or when the present air conditioning is determined
to be the pre-air condition in step S147 (if YES), the operation
proceeds to step S148 without selecting the operation of the engine
EG (engine ON).
[0316] When the outside air temperature Tam is determined to be
higher than -5.degree. C. in step S141 (if NO), the operation
proceeds to steps S151 to S155 so as to select the heat pump cycle.
The processes in steps S151 to S155 are the same as those of steps
S46 to S50 of the first embodiment, respectively.
[0317] By the processes of steps S151 to S155, one cycle is
appropriately selected from among the HOT cycle, DRY_EVA cycle, and
DRY_ALL cycle (heating mode, first dehumidification mode, and
second dehumidification mode) based on the possibility of fogging
of the windowpane and the necessity of dehumidification.
[0318] The air conditioning controller 50 of the present embodiment
turns the PTC heater 370N, while decreasing and correcting the
target coolant temperature when the remaining battery level is
sufficient, as in steps S142 to S145. As a result, a blown air
temperature near the TAO is obtained, while the operating rate of
the engine EG is reduced thereby to enable the power consumption
saving.
[0319] As the amount of air from the blower 32 becomes small, the
correction amount for decreasing the target coolant temperature is
increased, as in steps S144 and S145, so that it is possible for
the blown air temperature to be closer to the TAO.
Seventh Embodiment
[0320] In the above sixth embodiment, when the operation of the PTC
heater 37 (PTC ON) is selected, the target coolant temperature
correction amount fBLW is determined based on only a blower motor
voltage regardless of an operation power of the PTC heater 37. In
contrast, in a seventh embodiment, as shown in FIG. 15, when the
operation of the PTC heater 37 (PTC ON) is selected, the target
coolant temperature correction amount fBLW is determined based on
the blower motor voltage and the operation voltage of the PTC
heater 37.
[0321] Now, the process in step S6 of the present embodiment will
be described in more detail below. The flowchart of FIG. 15 is
obtained by changing steps S142 to S144 in the flowchart of FIG. 14
into steps S162 to S166, but other steps S167 to S178 of FIG. 15
are the same as corresponding steps S145 to S156 in FIG. 14.
[0322] When the outside air temperature Tam is determined to be
lower than -5.degree. C. in step S161 (corresponding to step S141
of FIG. 14) (if YES), a margin of the remaining battery level is
determined in step S162. In the present embodiment, the ratio of
the remaining battery level to the air conditioning interference
level (remaining battery level/air conditioning interference level)
is used as an index of the margin of the remaining battery
level.
[0323] When the ratio of the remaining battery level to the air
conditioning interference level is determined to be at an
intermediate level in step S162 (e.g., in the present embodiment,
in a range of 1.0 to 1.2), the remaining battery level is
determined to be sufficient. Then, the operation proceeds to step
S163 where the predetermined number of PTC heaters 37 (for 500 W in
the present embodiment) are operated.
[0324] Subsequently, in step S164, a target coolant temperature
correction amount fBLW is determined based on the blower voltage
(i.e., air amount), and in step S167 (corresponding to step S145 in
FIG. 14) the target coolant temperature is corrected with respect
to the TAO only by the target coolant temperature correction amount
fBLW (i.e., target coolant temperature=TAO+fBLW).
[0325] In the present embodiment, as the amount of air from the
blower 32 becomes small, the target coolant temperature correction
amount fBLW is increased in the negative direction (minus
direction), which makes the target coolant temperature lower than
the TAO. As a result, the operating rate of the engine EG is
reduced thereby to achieve the fuel consumption saving.
[0326] When the ratio of the remaining battery level to the air
conditioning interference level is determined to be large in step
S162 (1.2 or more in the present embodiment), the remaining battery
level is determined to be much sufficient. Then, the operation
proceeds to step S165 where the larger number of PTC heaters 37
(for 1000 W in the present embodiment) are operated as compared to
that in step S163.
[0327] Subsequently, in step S166, the target coolant temperature
correction amount fBLW is determined based on the blower voltage
(air amount). In step S167 (corresponding to step S145 in FIG. 14),
the target coolant temperature is corrected with respect to the TAO
only by the target coolant temperature correction amount fBLW
(target coolant temperature=TAO+fBLW).
[0328] In this case, the power for operating the PTC heater 37
becomes more than that in the case of step S163. Since the amount
of increase in blown air temperature by the PTC heater 37 becomes
large, the target coolant temperature correction amount fBLW is
made much larger in the negative (minus) direction, so that the
target coolant temperature is further lowered with respect to the
TAO, which improves the fuel consumption savings.
[0329] When the ratio of the remaining battery level to the air
conditioning interference level is determined to be small (less
than 1, in the present embodiment) in step S162, the PTC heater 37
cannot be operated. Then, the operation proceeds to step S168
(corresponding to step S146 shown in FIG. 14) where the target
coolant temperature is set high. In the present embodiment, the
target coolant temperature is set so as to be higher by 1.degree.
C. than the TAO (i.e., target coolant temperature=TAO+1.degree.
C.).
[0330] According to the present embodiment, as in steps S162 to
S167, as the margin of the remaining battery level becomes large,
the air conditioning controller 50 increases the capacity of the
PTC heater 37 thereby to increase the correction amount for
decreasing the target coolant temperature. Thus, the present
embodiment can obtain the blown air temperature near the TAO, while
further reducing the operating rate of the engine EG, thereby
achieving the fuel consumption saving.
Eighth Embodiment
[0331] In the seventh embodiment, as the margin of the battery
remaining level becomes larger, the capacity of the PTC heater 37
is enhanced. In contrast, in the eight embodiment, as shown in FIG.
16, as the margin of the remaining battery capacity becomes large,
the capacity of a seat heater 48 is enhanced.
[0332] That is, when the target coolant temperature is determined
regardless of operation or stop of the seat heater 48, the
passenger may feel excessively hot during the operation of the seat
heater 48, which may result in a practical problem going against
the fuel consumption saving.
[0333] Therefore, the present embodiment decreases the target
coolant temperature in the operation of the seat heater 48 thereby
to suppress the excessively hot feeling of the passenger, thus
achieving the fuel consumption saving.
[0334] Now, the process in step S9 of the present embodiment will
be described in more detail below. The flowchart of FIG. 16 is
obtained by changing steps S163 to S166 in the flowchart of FIG. 15
into steps S183 to S186, and other steps are the same as those in
FIG. 15. That is, steps S180 to S182 in FIG. 16 respectively
correspond to steps S160 to S162 of FIG. 15, and steps S187 to S198
in FIG. 16 respectively correspond to steps S167 to S178.
[0335] When the outside air temperature Tam is determined to be
lower than -5.degree. C. in step S181 (corresponding to step S161
of FIG. 15) (if YES), the margin of the remaining battery level is
determined in step S182 (corresponding to step S162 in FIG.
15).
[0336] When the ratio of the remaining battery level to the air
conditioning interference level is determined to be relatively
large in step S182 (1.0 to 1.2 in the present embodiment), the
remaining battery level is determined to be sufficient. Then, the
operation proceeds to step S183 where a seat heater 48 is selected
to be operated with a weak capacity in which power is small in
units of watt (i.e., a seat heater ON request (weak)).
[0337] Subsequently, in step S184, the target coolant temperature
correction amount fSEAT is determined based on the capacity (watts)
of the seat heater 48. In the present embodiment, the target
coolant temperature correction amount fSEAT is set to -3.degree. C.
(fSEAT=-3).
[0338] Subsequently, in step S187 (corresponding to step S167 in
FIG. 15), the target coolant temperature is corrected with respect
to the TAO only by the target coolant temperature correction amount
fSEAT (target coolant temperature=TAO+fSEAT). As a result, the
operating rate of the engine EG is reduced and thus the fuel
consumption saving is achieved.
[0339] When the ratio of the remaining battery level to the air
conditioning interference level is determined to be very large in
step S182 (i.e., 1.2 or more in the present embodiment), the
remaining battery level is determined to be very sufficient. Then,
the operation proceeds to step where the seat heater 48 is selected
to be operated with a strong capacity at more watts (i.e., a seat
heater ON request (strong)).
[0340] Subsequently, in step S186, the target coolant temperature
correction amount fSEAT is determined based on the capacity (watts)
of the seat heater 48. In the present embodiment, the target
coolant temperature correction amount fSEAT is set to -6.degree. C.
(fSEAT=-6).
[0341] Subsequently, in step S187 (corresponding to step S167 in
FIG. 15), the target coolant temperature is corrected with respect
to the TAO only by the target coolant temperature correction amount
fSEAT (i.e., target coolant temperature=TAO+fSEAT).
[0342] In this case, the capacity (in units of watt) of the seat
heater 48 becomes strong as compared to the case of step S183,
which greatly improves the warming feeling of the passenger through
the seat heater 48. Thus, the target coolant temperature correction
amount fBLW is made much larger in the negative (minus) direction,
thereby making the target coolant temperature much lower. Thus, the
effect of the fuel consumption saving is enhanced.
[0343] According to the present embodiment, as in steps S182 to
S187, when the remaining battery level is sufficient, the air
conditioning controller 50 turns the seat heater 480N, while
decreasing and correcting the target coolant temperature, thereby
to ensure the warm feeling of the passenger, while reducing the
operating rate of the engine EG, thus enabling the fuel consumption
saving.
[0344] As the margin of the remaining battery level becomes large,
the air conditioning controller 50 increases the capacity of the
seat heater 48 thereby to increase the correction amount for
decreasing the target coolant temperature by the amount of increase
in capacity. Thus, the air conditioner can further reduce operating
rate of the engine EG, while ensuring the warm feeling of the
passenger, thus enabling the fuel consumption saving.
Ninth Embodiment
[0345] In a ninth embodiment, the process in step S7, that is, the
way to determine a blower motor voltage of the blower 32 will be
described in more detail below.
[0346] FIG. 17 is a flowchart showing a main part of the process in
step S7. The control process shown in the flowchart of FIG. 17 is
carried out when the automatic switch 60b is turned on (ON) or the
like.
[0347] In step S200, it is determined whether a control mode of the
blower 32 (blower motor voltage) is an automatic mode or not. When
the control mode is determined not to be the automatic mode (that
is, to be the manual mode) (if NO), the operation proceeds to step
S201. In step S201, a blower motor voltage is determined based on a
manual blowing level set by an operation of the air amount setting
switch of the blower 32. In the present embodiment, the blower
motor voltage is determined according to five levels, namely, Hi,
M3, M2, M1, and Lo.
[0348] When the control mode is determined to be the automatic mode
in step S200 (if YES), the operation proceeds to step S202 where
the automatic air amount as a basis is determined based on the TAO.
The term "automatic air amount as a basis" is a temporary value of
a blower motor voltage determined in the automatic mode. In
contrast, the last determination of the blower motor voltage in the
automatic mode is made in step S208 to be described later. In the
present embodiment, the automatic air amount as the basis is
determined based on the map shown in step S202 of FIG. 17.
[0349] Subsequently, in step S203, it is determined whether the
remaining battery level is very sufficiently or not. In the present
embodiment, when the remaining battery level is more than the value
obtained by multiplying the air conditioning interference level by
a safety factor of 1.2 (air conditioning interference
level.times.1.2) (if YES), the remaining battery level is
determined to be very sufficient, and the operation proceeds to
step S204.
[0350] In step S204, it is determined whether the engine EG is
being operated (turned ON) or not. When the engine is determined to
be turned ON (if YES), the operation proceeds to step S205 where it
is determined whether the PTC heater 37 is being operated (turned
ON) or not. When the PTC heater is determined to be turned ON (if
YES), the operation proceeds to step S206 where the blower voltage
correction amount is set to -1 V so as to decrease and correct the
automatic air amount as the basis (blower voltage correction
amount=-1 V).
[0351] When the negative determination is made in step S203, S204,
or S205 (if NO), the operation proceeds to step S207 where the
blower voltage correction amount is set to 0 V so as to obtain the
blower motor voltage finally determined in the automatic mode as
the basis automatic air amount (blower voltage correction amount=0
V).
[0352] After setting the blower voltage correction amount in steps
S206 and S207, the blower motor voltage in the automatic mode is
finally determined in step S208. In the present embodiment, a value
obtained by adding the blower voltage correction amount to the
automatic air amount as the basis is defined as the blower motor
voltage finally determined in the automatic mode (i.e., automatic
air amount=automatic air amount as basis+blower voltage correction
amount), at step S208.
[0353] According to the present embodiment, as in steps S203 to
S206 and S208, when the PTC heater 37 and the engine EG are
operated (turned ON), the air conditioning controller 50 decreases
the blower motor voltage to reduce the amount of air from the
blower 32, and hence can improve the effect of increase of the
blown air temperature by the PTC heater 37.
[0354] Even when the operating rate of the engine EG is reduced and
the engine coolant temperature Tw is decreased, the air conditioner
can obtain the blown air temperature near the TAO, thus ensuring
the heating capacity, while achieving the fuel consumption
saving.
Other Embodiments
[0355] Although the present invention 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.
[0356] For example, although the possibility of fogging of the
windowpane is determined based on the relative humidity RHW of the
surface of the windowpane in each of the above embodiments, the
invention is not limited thereto. For example, the possibility of
fogging of the windowpane may be determined based on the outside
air temperature Tam, TAO, vehicle speed, the number of passengers,
and the like.
[0357] For example, various appropriate modifications can be made
to the criterion for determining the possibility of fogging of the
windowpane, or the criterion for determining the necessity of
dehumidification in the respective embodiments described above.
[0358] For example, a predetermined threshold of the outside air
temperature Tam in steps S31, S42, and the like of the above first
embodiment can be appropriately modified.
[0359] For example, the criterion for determining whether the
engine coolant temperature Tw is lower or not in step S36 of the
above first embodiment can be appropriately modified.
[0360] For example, the predetermined temperature to be compared
with the engine coolant temperature Tw in step S72 or the like of
the above third embodiment can be appropriately modified.
[0361] For example, the processes in step S33 to S39 in the above
first embodiment may be omitted. That is, when the outside air
temperature Tam is determined to be an extreme-low temperature in
step S31 (if YES), only a request for turning the engine ON may be
made in step S32.
[0362] For example, the processes in steps S72, S73, S75 to S78,
and the like in the above third embodiment may be omitted. That is,
when the outside air temperature Tam, is determined to be a low
temperature in step S71 (if YES), the request for turning the
engine ON may be made in step S74, and the heat pump cycle may be
selected in steps S85 to S89.
[0363] For example, the processes in steps S92, S93, S95 to S98,
and the like in the above fourth embodiment may be omitted. That
is, when the outside air temperature Tam is higher than the first
predetermined temperature T1 and lower than the second
predetermined temperature T2 in steps S90 and S91 (if YES in step
S91), the request for turning the engine ON may be made in step S94
and the heat pump cycle may be selected in steps S101 to S105.
[0364] For example, in the above fifth embodiment, turning on or
off (ON or OFF) of the compressor 11 is determined based on the
discharge refrigerant pressure Pd of the compressor 11, but may be
determined based on the suction refrigerant pressure of the
compressor 11.
[0365] The above respective embodiments of the invention may be
combined together in a practicable range.
[0366] For example, the above first and sixth embodiments may be
combined together. Specifically, the air conditioning controller 50
may output operation request signals to the internal combustion
engine EG and the PTC heater 37 when the outside air temperature
Tam is lower than a predetermined threshold. Further, the air
conditioning controller 50 may decrease and correct the target
coolant temperature when the PTC heater 37 is operated.
[0367] For example, the above first and seventh embodiments may be
combined together. Specifically, the air conditioning controller 50
may output operation request signals to the internal combustion
engine EG and the PTC heater 37 when the outside air temperature
Tam is lower than the predetermined threshold. Further, as the
power consumption, of the PTC heaters 37 becomes large, the
correction amount for decreasing the target coolant temperature may
be increased.
[0368] For example, at least two of the above first and eighth
embodiments may be combined together. Specifically, the air
conditioning controller 50 may output operation request signals to
the internal combustion engine EG and the seat heater 48 when the
outside air temperature Tam is lower than the predetermined
threshold. Further, the air conditioning controller 50 may decrease
and correct the target coolant temperature when the seat heater 48
is operated. Moreover, as the power consumption of the seat heater
48 becomes large, the correction amount for decreasing the target
coolant temperature may be increased.
[0369] Such changes and modifications are to be understood as being
within the scope of the present invention as defined by the
appended claims.
* * * * *