U.S. patent application number 10/066352 was filed with the patent office on 2002-08-08 for vehicular air conditioner.
Invention is credited to Imai, Takayuki, Murase, Masakazu, Yokomachi, Naoya.
Application Number | 20020104327 10/066352 |
Document ID | / |
Family ID | 18893197 |
Filed Date | 2002-08-08 |
United States Patent
Application |
20020104327 |
Kind Code |
A1 |
Murase, Masakazu ; et
al. |
August 8, 2002 |
Vehicular air conditioner
Abstract
A first external refrigerant circuit includes a condenser, a
pressure reducing device, and an evaporator. A compressor is
directly connected to a drive source of the vehicle to permit power
transmission and compresses a refrigerant by being driven by the
drive source at all times. The compressor and the first external
refrigerant circuit form a refrigerant circulation circuit. A
second external refrigerant circuit connects a discharge chamber
and a suction chamber of the compressor at the outside of the
compressor and permits the circulation of a refrigerant that is not
involved in air conditioning. Control devices selectively open or
close the first external refrigerant circuit and the second
external refrigerant circuit, respectively.
Inventors: |
Murase, Masakazu;
(Kariya-shi, JP) ; Imai, Takayuki; (Kariya-shi,
JP) ; Yokomachi, Naoya; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
18893197 |
Appl. No.: |
10/066352 |
Filed: |
February 1, 2002 |
Current U.S.
Class: |
62/228.3 ;
417/222.2 |
Current CPC
Class: |
F25B 2313/0276 20130101;
F25B 2327/001 20130101; F25B 9/008 20130101; F25B 2309/061
20130101; F25B 40/00 20130101; F25B 2400/0409 20130101; F25B
2600/02 20130101; B60H 1/323 20130101; F25B 13/00 20130101 |
Class at
Publication: |
62/228.3 ;
417/222.2 |
International
Class: |
F25B 001/00; F04B
001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2001 |
JP |
2001-028749 |
Claims
1. A vehicular air conditioner comprising: a first external
refrigerant circuit including a condenser, a pressure reducing
device, and an evaporator; a compressor directly connected to a
drive source of the vehicle to permit power transmission, wherein
the compressor compresses refrigerant by being at all times driven
by the drive source, the compressor and the first external
refrigerant circuit forming a refrigerant circulation circuit; a
second external refrigerant circuit, which connects a discharge
chamber to a suction chamber of said compressor at the outside of
said compressor and permits the circulation of the refrigerant that
is not involved in air conditioning; and control means, which
selectively open or close said first external refrigerant circuit
and said second external refrigerant circuit, respectively.
2. The vehicular air conditioner according to claim 1, wherein said
second external refrigerant circuit partially shares its circuit
with said first external refrigerant circuit, and said second
external refrigerant circuit includes a bypass passage, which
connects the discharge chamber to the suction chamber of said
compressor in a state where the condenser or the evaporator in said
first external refrigerant circuit is bypassed.
3. The vehicular air conditioner according to claim 2, wherein said
first external refrigerant circuit includes an accumulator between
the evaporator and the suction chamber of said compressor and a
low-pressure side of said bypass passage is connected to said first
external refrigerant circuit between the evaporator and the
accumulator.
4. The vehicular air conditioner according to claim 2, wherein said
first external refrigerant circuit includes an internal heat
exchanging device, said internal heat exchanging device having a
high-pressure side heat exchanger through which the refrigerant
flows from the discharge chamber of the compressor to the pressure
reducing device, and a low-pressure side heat exchanger through
which the refrigerant flows from the evaporator to the suction
chamber of the compressor, heat exchange being executed between the
high-pressure side and low-pressure side heat exchangers, and that
the low-pressure side of said bypass passage is connected between
the evaporator and the low-pressure side heat exchanger of the
internal heat exchanging device in said first external refrigerant
circuit.
5. The vehicular air conditioner according to claim 2, wherein the
high-pressure side of said bypass passage is connected between the
condenser and the pressure reducing device, in said first external
refrigerant circuit.
6. The vehicular air conditioner according to claim 2, wherein said
first external refrigerant circuit includes an oil separator for
separating oil from the refrigerant between the discharge chamber
of the compressor and the condenser, and said oil separator is
connected to the suction chamber of the compressor through an oil
return passage for returning a separated oil into the compressor,
said oil return passage also serving as the bypass passage.
7. The vehicular air conditioner according to claim 1, wherein said
first external refrigerant circuit includes an external heat
exchanger, which functions as said condenser during the cooling and
functions as said evaporator during the heating, and an internal
heat exchanger, which functions as said evaporator during the
cooling and functions as said condenser during the heating, and
said first external refrigerant circuit further includes a
switching valve switchable to two positions for switching said
first external refrigerant circuit to the cooling mode and the
heating mode, and when the first external refrigerant circuit is
switched to the cooling mode by the switching valve, a passage from
the discharge chamber of the compressor to the suction chamber of
the compressor through the external heat exchanger that functions
as the condenser and the internal heat exchanger that functions as
the evaporator is formed in the first external refrigerant circuit,
and that when the first external refrigerant circuit is switched to
the heating mode by said switching valve, a passage from the
discharge chamber of the compressor to the suction chamber of the
compressor through the internal heat exchanger that functions as
the condenser and the external heat exchanger that functions as the
evaporator is formed in the first external refrigerant circuit.
8. The vehicular air conditioner according to claim 7, wherein said
switching valve can be disposed at a position where said first
external refrigerant circuit is shut off and said second external
refrigerant circuit is opened, and also serves as said control
means.
9. The vehicular air conditioner according to claim 1, wherein the
discharge displacement of said compressor can be changed.
10. The vehicular air conditioner according to claim 9, wherein
said compressor includes a cam plate and a crank chamber that
accommodates the cam plate, a discharge displacement is adjusted by
changing the inclination angle of the cam plate by adjusting the
pressure in the crank chamber, and when said first external
refrigerant circuit is shut off by said control means, an internal
refrigerant circulation circuit is formed within said compressor,
which circulation circuit starts from the discharge chamber and
returns to the discharge chamber through the crank chamber and the
suction chamber.
11. The vehicular air conditioner according to claim 10, wherein
when the discharge displacement of the compressor becomes a
minimum, said first external refrigerant circuit is shut off in
association therewith.
12. The vehicular air conditioner according to claim 10, wherein
while the refrigerant is circulating in said internal refrigerant
circulation circuit, when a physical quantity that indicates a
heat-generation state of the compressor or a physical quantity that
influences heat-generation state of the compressor shows
deterioration of the heat-generation state of the compressor, said
second external refrigerant circuit is opened.
13. The vehicular air conditioner according to claim 12, wherein
said control means includes: an electromagnetic control valve that
selectively opens or closes said second external refrigerant
circuit by an electric power supply control from the outside, a
sensor, which detects the physical quantity that exhibits a
heat-generation state of the compressor or the physical quantity
that influences the heat-generation state of the compressor, and a
controller that commands said electric control valve to open the
second external refrigerant circuit when the detected information
from said sensor shows deterioration of the heat-generation state
of the compressor while said refrigerant circulates in said
internal refrigerant circulation circuit.
14. The vehicular air conditioner according to claim 12, wherein
said control means includes a sensing member, which senses the
physical quantity that indicates the heat-generation state of the
compressor or the physical quantity that influences the
heat-generation state of the compressor, and operates, said control
means opens said second external refrigerant circuit by the
operation of said sensing member when a heat-generation state of
the compressor deteriorates while a refrigerant circulates in the
internal refrigerant circuit.
15. The vehicular air conditioner according to claim 1, wherein
carbon dioxide is used as said refrigerant.
16. The vehicular air conditioner according to claim 1, wherein
said second external refrigerant circuit includes a
refrigerant-cooling heat exchanger.
17. The vehicular air conditioner according to claim 16, wherein
said refrigerant-cooling heat exchanger is a low-pressure side heat
exchanger of an internal heat exchanging device used in said first
external refrigerant circuit.
18. A vehicular air conditioner comprising: a compressor directly
connected to a drive source of a vehicle to permit power
transmission, wherein the compressor compresses a refrigerant by
being at all times driven by the drive source, wherein the
compressor includes a discharge chamber, a suction chamber, a cam
plate, and a crank chamber that accommodates the cam plate, a
discharge displacement is adjusted by changing the inclination
angle of the cam plate by adjusting the pressure in the crank
chamber; a first external refrigerant circuit including a
condenser, a pressure reducing device, and an evaporator; a second
external refrigerant circuit, which connects a discharge chamber to
a suction chamber of said compressor at the outside of said
compressor and permits the circulation of the refrigerant that is
not involved in air conditioning; and control means, which
selectively open or close said first external refrigerant circuit
and said second external refrigerant circuit, respectively;
wherein, when said first external refrigerant circuit is shut off
by said control means, an internal refrigerant circulation circuit
is formed within said compressor, which circulation circuit starts
from the discharge chamber and returns to the discharge chamber
through the crank chamber and the suction chamber.
19. The vehicular air conditioner according to claim 18, wherein
said second external refrigerant circuit partially shares its
circuit with said first external refrigerant circuit, and said
second external refrigerant circuit includes a bypass passage,
which connects the discharge chamber to the suction chamber of said
compressor in a state where the condenser or the evaporator in said
first external refrigerant circuit is bypassed.
20. The vehicular air conditioner according to claim 19, wherein
said first external refrigerant circuit includes an accumulator
between the evaporator and the suction chamber of said compressor
and a low-pressure side of said bypass passage is connected to said
first external refrigerant circuit between the evaporator and the
accumulator.
21. The vehicular air conditioner according to claim 19, wherein
said first external refrigerant circuit includes an internal heat
exchanging device, said internal heat exchanging device having a
high-pressure side heat exchanger through which the refrigerant
flows from the discharge chamber of the compressor to the pressure
reducing device, and a low-pressure side heat exchanger through
which the refrigerant flows from the evaporator to the suction
chamber of the compressor, heat exchange being executed between the
high-pressure side and low-pressure side heat exchangers, and that
the low-pressure side of said bypass passage is connected between
the evaporator and the low-pressure side heat exchanger of the
internal heat exchanging device in said first external refrigerant
circuit.
22. The vehicular air conditioner according to claim 19, wherein
the high-pressure side of said bypass passage is connected between
the condenser and the pressure reducing device, in said first
external refrigerant circuit.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a vehicular air conditioner
provided with a compressor that is directly connected to a drive
source of a vehicle so that power transmission is possible, and the
compressor executes compression of refrigerant driven at all times
by the drive source of the vehicle.
[0002] Swash plate type compressors used in, for example, a
vehicular air conditioner include a clutchless type having no
clutch mechanism on a power transmission path between the
compressor and the engine of the vehicle. For the clutchless
compressor, a variable displacement type has been generally used.
In the compressor, the discharge displacement can be changed by
changing the pressure in a crank chamber, and the discharge
displacement is minimized when cooling is not needed.
[0003] In the clutchless compressor, the minimum discharge
displacement is set to near zero when no cooling is needed, in
order to reduce the load on the engine. Therefore, at the minimum
discharge displacement of the compressor, the refrigerant flow rate
in a refrigerant circulation circuit becomes small. As a result,
the amount of lubricating oil that returns to the compressor
together with the refrigerant becomes small.
[0004] Therefore, in the prior art, when the discharge displacement
of the compressor is minimized, the circulation of the refrigerant
that passes through an external refrigerant circuit is stopped and,
at the same time, an internal refrigerant circulation circuit that
passes through a discharge chamber, a crank chamber, a suction
chamber and a compression chamber (and to the discharge chamber) is
formed. Then, the state of lubrication of each sliding portion in
the compressor is favorably maintained by lubricating oil
circulating with the refrigerant in this internal refrigerant
circulation circuit.
[0005] However, in the state of minimum discharge displacement (the
state of the internal refrigerant circulation) for the clutchless
compressor, when the thermal environment of the compressor becomes
severe as the rotational speed of the engine becomes high, or when
the outside air temperature becomes high, the temperature of the
refrigerant and the lubricating oil that circulate within the
compressor is excessively increased inside the compressor and
components of the compressor are exposed to a thermally severe
environment.
[0006] Particularly, when carbon dioxide is used as the
refrigerant, the refrigerant pressure becomes significantly higher
than when chlorofluorocarbon refrigerant is used. Thus, in the
state of the minimum discharge displacement, the temperature inside
the compressor increases more significantly than when the
chlorofluorocarbon refrigerant is used.
[0007] The above-mentioned problems can be solved by continuously
supplying the refrigerant to the external refrigerant circuit, even
when cooling is unnecessary, to prevent heat increase in the
compressor. However, this results in unnecessary air
conditioning.
BRIEF SUMMARY OF THE INVENTION
[0008] The object of the present invention is to provide an air
conditioner that can improve durability of a clutchless compressor
without executing unnecessary air conditioning.
[0009] To attain the above-described object, according to the
present invention, a vehicular air conditioner is provided. The air
conditioner includes a first external refrigerant circuit, a
compressor, a second external refrigerant circuit and control
means. The first external refrigerant circuit includes a condenser,
a pressure reducing device, and an evaporator. The compressor is
directly connected to a drive source of the vehicle to permit power
transmission. The compressor compresses a refrigerant by being at
all times driven by the drive source. The compressor and the first
external refrigerant circuit form a refrigerant circulation
circuit. The second external refrigerant circuit connects a
discharge chamber to a suction chamber of the compressor at the
outside of the compressor and permits the circulation of a
refrigerant that is not involved in air conditioning. The control
means selectively open or close the first external refrigerant
circuit and the second external refrigerant circuit,
respectively.
[0010] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0011] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0012] FIG. 1 is a circuit diagram of a vehicular air conditioner
of a first embodiment;
[0013] FIG. 2 is a flowchart explaining the processing of a
controller;
[0014] FIG. 3 is a cross-sectional view of a bypass control valve
showing a second embodiment;
[0015] FIG. 4 is a circuit diagram of a vehicular air conditioner
of a third embodiment;
[0016] FIG. 5 is a circuit diagram of a vehicular air conditioner
of a fourth embodiment; and
[0017] FIGS. 6(a), 6(b), and 6(c) are circuit diagrams of a
vehicular air conditioner of a fifth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The first to fifth embodiments in which the present
invention has been embodied will be described below. It should be
noted that in the second to fifth embodiments, only the difference
from the first embodiment is described and that the same numeral is
denoted to the same member or the corresponding member to omit the
explanation.
First Embodiment
[0019] As shown in FIG. 1, a variable displacement type swash plate
compressor C (hereinafter referred simply to as a compressor C)
includes a cylinder block 1, a front housing 2 fixed to the front
end thereof, and a rear housing 4 fixed to the rear end of the
cylinder block 1 through a valve plate 3.
[0020] A crank chamber 5 is defined in a region surrounded by the
cylinder block 1 and the front housing 2. A drive shaft 6 is
rotatably provided in the crank chamber 5. The drive shaft 6 is
directly connected to an output shaft (not shown) of an engine E,
which is a drive source of a vehicle, not by way of a clutch
mechanism such as an electromagnetic clutch. Thus, the drive shaft
6 is always driven to be rotated by the engine E in operation of
the engine E.
[0021] As described above, since the compressor C does not include
an expensive and heavy electromagnetic clutch on a power
transmission path between the engine E and the compressor C, it is
inexpensively provided. Additionally, since the light weight of the
compressor C can be achieved and the shock due to the on-off of the
electromagnetic clutch does not occur, deterioration in drivability
can be prevented.
[0022] In the crank chamber 5, a lug plate 11 is secured to the
drive shaft 6 so that it can rotate integrally therewith. A cam
plate, or a swash plate 12, is accommodated in the crank chamber 5.
The swash plate 12 is slidably and tiltably supported by the drive
shaft 6. A hinge mechanism 13 is placed between the lug plate 11
and the swash plate 12. Thus, the swash plate 12 is rotatable
integrally with the lug plate 11 and the drive shaft 6 by coupling
with the lug plate 11 through the hinge mechanism 13 and by support
of the drive shaft 6, and is tiltable with respect to the drive
shaft 6 while slide moving along the axial direction of the drive
shaft 6.
[0023] A plurality of cylinder bores 1a (only one shown in FIG. 1)
are formed to surround the drive shaft 6 in the cylinder block 1. A
single headed piston 20 is reciprocally accommodated in each
cylinder bore 1a. The front and rear openings of the cylinder bore
1a are respectively closed by the valve plate 3 and the piston 20.
In each cylinder bore 1a is defined a compression chamber 29 whose
volume is changed in accordance with the reciprocation of the
piston 20. Each piston 20 is coupled to the peripheral portion of
the swash plate 12 through shoes 19. Therefore, the rotation of the
swash plate 12 caused by the rotation of the drive shaft 6 is
converted to linear reciprocation of the piston 20 through the
shoes 19.
[0024] A suction chamber 21 and a discharge chamber 22 are defined
between the valve plate 3 and the rear housing 4. A refrigerant gas
in the suction chamber 21 is sucked into the compression chamber 29
through a suction port 23 and a suction valve 24 formed in the
valve plate 3 by movement of each piston 20 from the top dead
center position toward the bottom dead center position. The
refrigerant gas sucked into the compression chamber 29 is
compressed to a predetermined pressure by movement of the piston 20
from the bottom dead center position toward the top dead center
position and is discharged to the discharge chamber 22 through a
discharge port 25 and a discharge valve 26 formed in the valve
plate 3.
[0025] A crank pressure control mechanism for controlling pressure
in the crank chamber 5 (crank pressure) relating to the control of
the inclination angle of the swash plate 12, is comprised of a
bleed passage 27, a supply passage 28 and a control valve 31 formed
in the housing of the compressor. The bleed passage 27 connects the
crank chamber 5 to the suction chamber 21. The supply passage 28
connects the discharge chamber 22 to the crank chamber 5, and the
control valve 31 is provided therebetween.
[0026] The control valve 31 is comprised of an electromagnetic
valve and includes a valve body 31a for adjusting the degree of
opening of the supply passage 28 and an electromagnetic actuator
31b, which causes the valve body 31a to operate by controlling
electric current supplied from the outside. The electromagnetic
actuator 31b is controlled by a controller 51 in accordance with
detected information (cooling load or the like) from an information
detector 52. The electromagnetic actuator 31b causes the valve body
31a to operate in accordance with the amount of current to adjust
the degree of opening of the supply passage 28.
[0027] Accordingly, a balance between the amount of high pressure
discharge gas introduced to the crank chamber 5 through the supply
passage 28 and the amount of gas relieved from the crank chamber 5
through the bleed passage 27 is controlled and a crank pressure is
determined. According to the crank pressure, the difference between
the crank pressure and the internal pressure in the compression
chamber 29 through the piston 20 is changed so that an inclination
angle of the swash plate 12 (an angle formed by the swash plate and
an imaginary plane perpendicular to the drive shaft 6) is changed.
As a result, a stroke of the piston 20, that is a discharge
displacement, is adjusted.
[0028] When the degree of opening of the control valve 31 is
decreased, the crank pressure decreases and the difference between
the crank pressure and the internal pressure in the compression
chamber 29 also decreases so that the inclination angle of the
swash plate 12 increases. As a result, the discharge displacement
of the compressor C increases. FIG. 1 shows a state where the swash
plate 12 is abutted against the lug plate 11 so that it is
restricted to the position where the inclination angle becomes the
maximum. At that time, the discharge displacement of the compressor
C becomes the maximum.
[0029] On the contrary, when the degree of opening of the control
valve 31 is increased, the crank pressure increases and the
difference between the crank pressure and the internal pressure in
the compression chamber 29 also increases so that the inclination
angle of the swash plate 12 decreases. As a result, the discharge
displacement of the compressor C decreases. An imaginary line in
FIG. 1 shows a state where the swash plate 12 is abutted against
the minimum inclination angle restricting portion 14 so that it is
restricted to the position where the inclination angle is the
minimum. At that time, the discharge displacement of the compressor
C becomes the minimum. The state of this minimum discharge
displacement is provided by full opening of the control valve 31.
It should be noted that the minimum inclination angle of the swash
plate 12 is set to near zero (for example, 2 to 5 degrees).
Therefore, in the state of the minimum discharge displacement, the
load torque of the compressor C is small and the load of the
compressor C on the engine E is small.
[0030] As shown in FIG. 1, the information detector 52 includes an
air conditioning switch 53, which is an on-off switch of an air
conditioner, a temperature setting device 54 for setting
temperature of a vehicle compartment, a vehicle compartment
temperature sensor 55 for detecting temperature of the vehicle
compartment, an outside-air temperature sensor 56 for detecting the
outside-air temperature, a housing temperature sensor 57 for
detecting temperature of housings 1, 2 and 4 of the compressor C, a
fluid temperature sensor 58 for detecting temperature of fluid
(refrigerant and lubricating oil) flowing within the compressor,
and a rotational speed sensor 59 for detecting a rotational speed
of an output shaft of the engine E, which has a unique relation to
the rotational speed of the drive shaft 6.
[0031] In the present embodiment, the outside-air temperature
sensor 56, the housing temperature sensor 57, the fluid temperature
sensor 58, and the rotational speed sensor 59 of the information
detector 52 constitute a heat-generation state detecting
sensor.
[0032] For example, when the refrigerant temperature within the
compressor increases, the housing temperature also increases. On
the other hand, when the refrigerant temperature within the
compressor decreases, the housing temperature also decreases. That
is, the housing temperature is a physical quantity having a
correlation with the refrigerant temperature, and both of them are
physical quantities representing the heat-generation state of the
compressor C. Thus, the housing temperature sensor 57 can be
considered as a fluid temperature sensor as well. Further, when the
outside-air temperature or the rotational speed of the engine E
(drive shaft) increases, the refrigerant temperature also
increases. On the contrary, when the outside-air temperature or the
rotational speed of the engine E (drive shaft) decreases, the
refrigerant temperature also decreases. That is, the outside-air
temperature and the rotational speed of engine E are physical
quantities, which influence on the refrigerant temperature, that
is, the heat-generation state of the compressor C.
[0033] As shown in FIG. 1, a refrigerant circulation circuit
(refrigeration cycle) of a vehicular air conditioner includes the
compressor C and a first external refrigerant circuit 41, which
connects the discharge chamber 22 to the suction chamber 21 of the
compressor C. The first external refrigerant circuit 41 is provided
with, in the order from the high pressure side (discharge chamber
22 side), a shut-off valve 42, an outdoor heat exchanger 43 that
functions as a condenser, a high-pressure side heat exchanger 44a
of an internal heat exchanging device 44, an expansion valve 45
that functions as a pressure reducing device, an indoor heat
exchanger 46 that functions as an evaporator, an accumulator
(gas/liquid separator) 47, and a low-pressure side heat exchanger
44b of the internal heat exchanging device 44. Carbon dioxide is
used as a refrigerant.
[0034] The shut-off valve 42 forms a control means of the external
refrigerant circuit, and when pressure on the side of the discharge
chamber 22 becomes lower than a predetermined value, the shut-off
valve 42 shuts off the refrigerant passage so that the circulation
of the refrigerant that passes through the first external
refrigerant circuit 41, is stopped. The shut-off valve 42 may be a
differential pressure type that mechanically detects the difference
in pressure of the front and the back of the shut-off valve 42, or
an electromagnetic valve type whose electric power supply is
controlled by a controller 51 in accordance with a detected value
by a discharge pressure sensor (not shown). Further, the shut-off
valve 42 may be a type that is mechanically linked to the minimum
inclination angle of the swash plate 12.
[0035] The accumulator 47 separates the refrigerant into a gas
phase and a liquid phase and at the same time sends the separated
gas refrigerant toward the suction chamber 21 side of the
compressor C.
[0036] The internal heat exchanging device 44 executes heat
exchange between the high-pressure refrigerant flowing in the
high-pressure side heat exchanger 44a and the low-pressure
refrigerant flowing in the low-pressure side heat exchanger 44b. In
this way, by executing heat exchange between the high-pressure
refrigerant and the low-pressure refrigerant, a specific enthalpy
at the inlet of the indoor heat exchanger 46 can be reduced as
compared with the case where the heat exchange is not executed.
Thus, the cooling performance and efficiency of the air conditioner
are improved.
[0037] Further, in the first external refrigerant circuit 41, point
P between the discharge chamber 22 of the compressor C and the
shut-off valve 42 communicates with point Q between the indoor heat
exchanger 46 and the accumulator 47 through a bypass passage (pipe)
61. The bypass passage 61 bypasses the shut-off valve 42, the
outdoor heat exchanger 43, the high-pressure side heat exchanger
44a, the expansion valve 45 and the indoor heat exchanger 46.
[0038] A second external refrigerant circuit 62 includes a passage
between the contact point P on the high-pressure side of the bypass
passage 61 and the discharge chamber 22, the bypass passage 61
between the two contact points P and Q, and a passage between the
contact point Q on the low-pressure side of the bypass passage 61
and the suction chamber 21. Since the accumulator 47 and the
low-pressure side heat exchanger 44b of the internal heat
exchanging device 44 are disposed on the passage between the
contact point Q and the suction chamber 21, they are also included
in the second external refrigerant circuit 62. The second external
refrigerant circuit 62 uses a part of the first external
refrigerant circuit 41 in common. The low-pressure side heat
exchanger 44b also serves as a heat exchanger for cooling a
refrigerant.
[0039] A bypass control valve 63 as an electromagnetic valve is
provided on the bypass passage 61. The bypass control valve 63
constitutes external refrigerant circuit control means and can open
or close (switches) the bypass passage 61 (second external
refrigerant circuit 62) by the electric power supply control from
the controller 51. The controller 51 usually shuts off the bypass
passage 61 through the bypass control valve 63, and opens the
bypass passage 61 only in a special case.
[0040] Next, operation of the air conditioner in the present
embodiment will be described.
[0041] When the controller 51 detects that cooling is not required
through the information detector 52, which, for instance, detects
that the air conditioning switch 53 is off, it commands control
valve 31 to fully open the supply passage 28. Therefore, the
discharge displacement of the compressor C is minimized. In this
state of the minimum discharge displacement, the pressure of the
shut-off valve 42 in the discharge chamber 22 side becomes lower
than a predetermined value, so that the shut-off valve 42 is
closed. Further, the bypass passage 61 is in the shut-off state by
the bypass control valve 63. Accordingly, the circulation of the
refrigerant passed through the first external refrigerant circuit
41 and the second external refrigerant circuit 62, that is, the
external circulation of the refrigerant is stopped.
[0042] Since the minimum inclination angle of the swash plate 12 is
not zero, even if the discharge displacement of the compressor C is
minimized, the suction of the refrigerant gas from the suction
chamber 21 to the compression chamber 29, the compression of the
refrigerant gas and the discharge thereof from the compression
chamber 29 to the discharge chamber 22 are continued. Therefore, in
the inside of the compressor C, a circulation circuit consisting of
the discharge chamber 22, the supply passage 28, the crank chamber
5, the bleed passage 27, the suction chamber 21, the compression
chamber 29 and the discharge chamber 22 is formed and lubricating
oil circulates in the internal refrigerant circulation circuit
together with the refrigerant. This prevents the lubricating oil
from being discharged outside the compressor C and the lubrication
condition of each slide portion (for example, between the swash
plate 12 and the shoe 19) is favorably maintained.
[0043] Then, the controller 51 starts an operation shown in the
flowchart of FIG. 2 in the state of the minimum discharge
displacement (the state of the internal refrigerant circulation) of
the compressor C.
[0044] That is, in step (hereinafter referred simply to as S) 101,
it is determined whether or not a heat generation state N of the
compressor C is a deterioration state (N>Nset) based on the
detected information from the heat generation state detecting
sensors 56 to 59. Here, it should be noted that a state where the
heat generation state of the compressor C is in a deterioration
state means a state in which at least one of the following states
is satisfied, where the outside air temperature is a predetermined
reference outside air temperature or higher, the housing
temperature is a predetermined reference housing temperature or
higher, the refrigerant temperature is a predetermined reference
refrigerant temperature or higher, and the rotational speed of the
engine E is a predetermined reference rotational speed or higher,
and at the same time this state is maintained for a predetermined
time or longer.
[0045] If the determination of the S101 is NO, the shut-off state
of the bypass passage 61 by the bypass control valve 63 is
maintained in the procedure of S102. That is, an internal
refrigerant circulation state in the compressor C is continued.
[0046] On the contrary, if the determination of the S101 is YES,
the bypass control valve 63 is directed to open the bypass passage
61 in the procedure of S103, and a protection control is executed.
Thus, the internal refrigerant circulation in the compressor C is
stopped and at the same time, as shown by the arrow of a chain line
in FIG. 1, external circulation of refrigerant that passes through
the second external refrigerant circuit 62 is started. Then, the
discharge of the high-temperature refrigerant and the lubricating
oil held inside the compressor C to the outside are executed, and
cooling of the circulating refrigerant and the lubricating oil is
also executed due to the heat radiation from the pipe constituting
the second external refrigerant circuit 62 and the internal heat
exchanging device 44 (low-pressure side heat exchanger 44b).
Accordingly, the temperature inside the compressor C is decreased
and the components of the compressor C can be released from
thermally severe conditions.
[0047] The present embodiment with the above-described constitution
has the following effects.
[0048] (1) When the heat generation state of the compressor C in
the minimum discharge displacement state (internal refrigerant
circulation state) deteriorates, the external refrigerant
circulation via the second external refrigerant circuit 62 is
executed by opening the circuit 62. Since the second external
refrigerant circuit 62 does not pass through the indoor heat
exchanger 46, even if the refrigerant flows in the circuit 62, the
circuit 62 does not influence the air conditioning. Therefore, the
components of the compressor C can be prevented from falling into
thermally severe conditions without executing unnecessary cooling.
As a result, the durability of the compressor C can be improved.
Further, the use of carbon dioxide that exhibits significantly
higher pressure than chlorofluorocarbon refrigerant as the
refrigerant can be easily realized.
[0049] (2) The second external refrigerant circuit 62 partially
shares the refrigerant passage with the first external refrigerant
circuit 41. This can simplify the refrigerant circulation circuit
formation.
[0050] (3) The low-pressure side of the bypass passage 61 is
connected to the first external refrigerant circuit 41 at the point
Q between the indoor heat exchanger 46 and the accumulator 47, and
the accumulator 47 also constitutes the second external refrigerant
circuit 62. The accumulator 47 retains a large amount of
lubricating oil therein during the circulation of the refrigerant
that passes through the first external refrigerant circuit 41 due
to the function and the structure thereof, and during the
protection control, the amount of lubricating oil contained in the
refrigerant which is returned from the accumulator 47 to the
compressor C can be increased. This results in an improvement of
lubricating properties of the compressor C.
[0051] (4) The low-pressure side of the bypass passage 61 is
connected between the indoor heat exchanger 46 and the low-pressure
side heat exchanger 44b of the internal heat exchanging device 44
in the first external refrigerant circuit 41, and the low-pressure
side heat exchanger 44b also constitutes the second external
refrigerant circuit 62. Therefore, by a favorable heat radiation by
the low-pressure side heat exchanger 44b, the cooling effects of
the refrigerant and the lubricating oil during the protection
control are enhanced. This leads to a further improvement of
durability of the compressor C.
[0052] (5) The bypass control valve 63 consists of an
electromagnetic valve and opens or closes (switches) the bypass
passage 61 by electric power supply control from outside by the
controller 51. Thus, as compared with a case where an internal
control valve (refer to the second embodiment) is used as, for
example, the bypass control valve 63, there is no such possibility
that the bypass passage 61 (second external refrigerant circuit 62)
be opened while the shut-off valve 42 opens the first external
refrigerant circuit 41. Thus, the reliability of operation of the
bypass control valve 63 can be enhanced.
[0053] (6) In a state where the first external refrigerant circuit
41 and the second external refrigerant circuit 62 are shut off, the
refrigerant and the lubricating oil are circulating only inside the
compressor C. When the refrigerant is circulating inside the
compressor C, only in a case where a heat-generation state of the
compressor C deteriorates, the bypass control valve 63 opens the
second external refrigerant circuit 62. That is, when the
heat-generation state of the compressor C does not deteriorate, a
refrigerant circulation state inside the compressor C is maintained
so that sufficient amount of lubricating oil can circulate
internally. Thus, the lubrication environment of each slide portion
becomes favorable.
[0054] (7) The controller 51 refers to the outside air temperature
and the rotational speed of the engine E in determination of the
heat generation state of the compressor C. Thus, by grasping the
outside air temperature and the rotational speed of engine E, which
are factors that influence the heat generation state of the
compressor C, deterioration of the heat generation state can be
predicted so that a protection control can be executed in advance.
This results in a further improvement in durability of the
compressor C.
[0055] (8) The controller 51 refers to the housing temperature and
the refrigerant temperature in determination of the heat generation
state of the compressor C. Thus, by directly grasping the heat
generation state of the compressor C, the protection control can be
accurately taken.
Second Embodiment
[0056] The present embodiment is different from the above-described
first embodiment in that the bypass control valve 63 is replaced by
a bypass control valve 65, which is an internal control type as
shown in FIG. 3. The bypass control valve 65 consists of a sensing
member 65a and a valve body 65b. The sensing member 65a is disposed
on the bypass passage 61 and is made of a bimetal that deforms in
accordance with the temperature of the refrigerant and lubricating
oil, which flow into the passage 61. The valve body 65b is
integrally provided on the sensing member 65a so that it can open
or close the bypass passage 61 in accordance with the deformation
of the sensing member 65a.
[0057] Further, when the temperature of the refrigerant and the
lubricating oil is a predetermined value or lower, the bypass
control valve 65 shuts off the bypass passage 61, and when the
temperature of the refrigerant and the lubricating oil exceeds the
predetermined value, the bypass control valve 65 opens the bypass
passage 61. Under conditions where the refrigerant and the
lubricating oil are externally circulating via the first external
refrigerant circuit 41, it hardly happens that the temperature of
the refrigerant and the lubricating oil, which flow into the bypass
passage 61, exceeds a predetermined value, and the bypass passage
61 is maintained at a shut-off state.
[0058] However, in a state where the refrigerant is circulating
inside the compressor C, heat may be contained within the
compressor C and the temperature of the refrigerant and the
lubricating oil that flow into the bypass passage 61 may exceed a
predetermined value as described in the prior art. When this
temperature exceeds a predetermined value, the bypass control valve
65 opens the bypass passage 61 to execute the external refrigerant
circulation via the second external refrigerant circuit 62 as in
the protection control of the above-described first embodiment. As
a result, the components of the compressor C can be released from
thermally severe conditions.
[0059] The present embodiment has the same effects as the effects
(1) to (4) and (6) of the first embodiment. Further, since the
bypass control valve 65 is internally controlled and opens or
closes the bypass passage 61, an electrical constitution of the air
conditioner can be simplified and the computation load on the
controller 51 can be reduced.
Third Embodiment
[0060] As shown in FIG. 4, in the present embodiment, the shut-off
valve 42 is disposed between the heat exchanger 43 and the
high-pressure side heat exchanger 44a of the internal heat
exchanging device 44 in the first external refrigerant circuit 41.
Further, the high-pressure side of the bypass passage 61 is
connected to point R between the outdoor heat exchanger 43 and the
shut-off valve 42 in the external refrigerant circuit 41. Thus, the
second external refrigerant circuit 62 also includes the outdoor
heat exchanger 43 on its refrigerant passage.
[0061] The present embodiment has the same effects as in the
above-described first embodiment. Further, by excellent heat
radiation by the outdoor heat exchanger 43, the cooling effects of
the refrigerant and the lubricating oil during a protection control
are enhanced. This results in a further improvement of the
durability of the compressor C.
Fourth Embodiment
[0062] As shown in FIG. 5, in the present embodiment, an oil
separator 67 is positioned between the discharge chamber 22 of the
compressor C and the shut-off valve 42 in the first external
refrigerant circuit 41. The oil separator 67 separates misty
lubricating oil contained in the refrigerant gas discharged from
the discharge chamber 22, from the refrigerant gas. An oil storage
chamber 67a of the oil separator 67 is connected to the first
external refrigerant circuit 41 at the point Q between the indoor
heat exchanger 46 and the accumulator 47 through an oil return
passage 68.
[0063] Therefore, when the refrigerant is circulating via the first
external refrigerant circuit 41, the lubricating oil separated by
the oil separator 67 is returned, while being cooled, to the
suction chamber 21 within the compressor C through the oil return
passage 68, the contact point Q, the accumulator 47 and the
low-pressure side heat exchanger 44b. Thus, by providing the oil
separator 67, the flowing of lubricating oil into the heat
exchangers 43, 44a and 46 can be prevented and a deterioration of
the efficiency in heat exchange for the heat exchangers 43, 44a and
46 due to adhesion of the lubricating oil to the inside thereof can
be prevented. Further, in the compressor C, the lubricating oil
discharged outside is rapidly returned inside without being
interfered by the heat exchangers 43, 44a and 46. As a result, the
lubrication state of each slide portion can be favorably
maintained.
[0064] When the discharge displacement of the compressor C is
minimized and the refrigerant circulation via the first external
refrigerant circuit 41 is stopped by the shut-off valve 42, the
refrigerant and the lubricating oil that flowed into the oil
separator 67 from the discharge chamber 22 of the compressor C are
returned into the compressor C through the oil return passage 68
and a passage on the downstream (suction chamber 21) side from the
contact point Q of the oil return passage 68 in the first external
refrigerant circuit 41. That is, in the present embodiment, the oil
return passage 68 constitutes the second external refrigerant
circuit 62 while also serving as a bypass passage.
[0065] Further, the oil return passage (bypass passage) 68 is not
provided with the bypass control valve 63 provided in the first
embodiment, and the passage 68 is always kept open. Thus, when the
discharge displacement of the compressor C is minimized,
refrigerant circulation via the second external refrigerant
circulation 62 is executed at all times, but inner refrigerant
circulation within the compressor C is not executed.
[0066] In a state where the first external refrigerant circuit 41
is open by the shut-off valve 42, most of the refrigerant separated
from the oil at the oil separator 67 flow out toward the shut-off
valve 42 side, the path easy to flow, and it can be considered that
only the lubricating oil flows out of the oil separator 67 to the
oil return passage 68 although a little amount of refrigerant may
leak therein. Thus, the state where the refrigerant is not
circulating in the oil return passage is substantially the same as
the state where the second external refrigerant circuit 62 is
shut-off. In that sense, the shut-off valve 42 also indirectly
opens or closes the second external refrigerant circuit 62.
Therefore, in the present embodiment, a combination of the shut-off
valve 42 with the oil separator 67 provided on the upstream side of
the shut-off valve 42 in the first external refrigerant circuit 41
constitutes control means for the external refrigerant circuit.
[0067] The present embodiment has the same effects as the effects
(2) to (4) of the above-described first embodiment and additionally
has the following effects.
[0068] (1) In the state of the minimum discharge displacement of
the compressor C, the external refrigerant circulation via the
second external refrigerant circuit 62 is executed at all times,
and the circulating refrigerant and lubricating oil are cooled by
the heat radiation of the pipe constituting the second external
refrigerant circuit 62 and the internal heat exchanging device 44
(low-pressure side heat exchanger 44b). Thus, the compressor C does
not fall into thermally severe conditions. Further, since the
second external refrigerant circuit 62 does not pass through the
indoor heat exchanger 46, even if the refrigerant flows in the
circuit 62, it does not affect air conditioning. Therefore, the
components of the compressor C can be prevented from falling into
thermally severe conditions without executing unnecessary cooling.
As a result, the durability of the compressor C can be improved.
Further, the use of carbon dioxide that exhibits significantly
higher pressure as a refrigerant than chlorofluorocarbon
refrigerant can be easily realized.
[0069] (2) As a bypass passage, the oil return passage 68 from the
oil separator 67 is utilized, and as compared with a case where an
exclusive bypass passage is provided, the formation of the
refrigerant circuit can be simplified.
[0070] (3) When the first external refrigerant circuit 41 is opened
by the shut-off valve, substantial shut-off of the second external
refrigerant circuit 62, that is, the stop of the refrigerant
circulation is executed by the oil separator 67. On the contrary,
when the first external refrigerant circuit 41 is shut off by the
shut-off valve 42, the second external refrigerant circuit 62 is
opened, that is, the refrigerant circulation is started in the same
manner by the oil separator 67. Therefore, the bypass control valve
can be omitted, and the formation of the refrigerant circulation
circuit can be further simplified.
Fifth Embodiment
[0071] As shown in FIGS. 6(a), 6(b) and 6(c), a vehicular air
conditioner of the present embodiment causes, to permit heating of
the vehicle compartment, the indoor heat exchanger 46 to function
as a condenser in the above-mentioned first external refrigerant
circuit 41 and at the same time causes the outdoor heat exchanger
43 to function as an evaporator. That is, as shown in FIG. 6(a), in
the first external refrigerant circuit 41, the discharge chamber 22
of the compressor C, the outdoor heat exchanger 43, the indoor heat
exchanger 46 and the accumulator 47 are connected to a
cooling/heating switching valve 71, respectively. The
cooling/heating switching valve 71 consists of an electromagnetic
valve and is switched to three positions shown in FIGS. 6(a), 6(b)
and 6(c) by the electric power supply control from the controller
51. The cooling/heating switching valve 71 and the controller 51
constitute a cooling/heating switching means.
[0072] The cooling/heating switching valve 71 can change the valve
position to the cooling position shown in FIG. 6(a), the heating
position shown in FIG. 6(b) and non-air-conditioning position shown
in FIG. 6(c). When the cooling/heating switching valve 71 is set at
the cooling position shown in FIG. 6(a), the first external
refrigerant circuit 41 is set to the cooling mode and the discharge
chamber 22 of the compressor C is connected to the outdoor heat
exchanger 43, and at the same time the indoor heat exchanger 46 is
connected to the accumulator 47.
[0073] When the cooling/heating switching valve 71 is set at the
heating position shown in FIG. 6(b), the first external refrigerant
circuit 41 is set to the heating mode and the discharge chamber 22
of the compressor C is connected to the indoor heat exchanger 46,
and at the same time the outdoor heat exchanger 43 is connected to
the accumulator 47.
[0074] When the cooling/heating switching valve 71 is set at the
non-air-conditioning position shown in FIG. 6(c), the first
external refrigerant circuit 41 is set to the non-air-conditioning
mode and while the discharge chamber 22 of the compressor C is
connected to the accumulator 47, the connection of the outdoor heat
exchanger 43 to the indoor heat exchanger 46 is shut off.
[0075] As shown in FIG. 6(a), when the cooling/heating switching
valve 71 is switched to the cooling position, the refrigerant from
the discharge chamber 22 of the compressor C is sequentially passed
through the cooling/heating switching valve 71, the outdoor heat
exchanger 43, the high-pressure side heat exchanger 44a of the
internal heat exchanging device 44, the expansion valve 45, the
indoor heat exchanger 46, the cooling/heating switching valve 71,
the accumulator 47 and the low-pressure side heat exchanger 44b of
the internal heat exchanging device 44 to return to the suction
chamber 21 of the compressor C (the cooling mode of the first
external refrigerant circuit 41). Thus, the outdoor heat exchanger
43 serves as a condenser and the indoor heat exchanger 46 serves as
an evaporator as in the first embodiment so that cooling of the
vehicle compartment is executed by the endothermic action of the
indoor heat exchanger 46.
[0076] As shown in FIG. 6(b), when the cooling/heating switching
valve 71 is switched to the heating position, the refrigerant from
the discharge chamber 22 of the compressor C is sequentially passed
through the cooling/heating switching valve 71, the indoor heat
exchanger 46, the expansion valve 45, the high-pressure side heat
exchanger 44a of the internal heat exchanging device 44, the
outdoor heat exchanger 43, the cooling/heating switching valve 71,
the accumulator 47 and the low-pressure side heat exchanger 44b of
the internal heat exchanging device 44 to return to the suction
chamber 21 of the compressor C (the heating mode of the first
external refrigerant circuit 41). Thus, the indoor heat exchanger
46 serves as a condenser and the outdoor heat exchanger 43 serves
as an evaporator so that heating of the vehicle compartment is
executed by the heat radiation of the indoor heat exchanger 46.
[0077] It should be noted that in the heating mode, the refrigerant
whose pressure is reduced by the expansion valve 45, flows into the
high-pressure side heat exchanger 44a of the heat exchanging device
44. The refrigerant that flows in the high-pressure side heat
exchanger 44a and the refrigerant that flows in the low-pressure
side heat exchanger 44b are substantially the same in terms of the
temperature and the pressure, and heat exchange between the two
refrigerants does not actually occur.
[0078] As shown in FIG. 6(c), when the cooling/heating switching
valve 71 is switched to the non-air-conditioning position, the
refrigerant circulation via the first external refrigerant circuit
41 (which is used in the cooling mode or heatingmode) is stopped,
and at the same time the refrigerant from the discharge chamber 22
of the compressor C is returned to the suction chamber 21 of the
compressor C through the cooling/heating switching valve 71, the
accumulator 47 and the low-pressure side heat exchanger 44b of the
internal heat exchanging device 44. In this state, since the
refrigerant does not pass through the indoor heat exchanger 46, the
refrigerant circulation does not influence the air conditioning of
the vehicle compartment.
[0079] That is, the refrigerant passage that passes through the
cooling/heating switching valve 71, the accumulator 47 and the
low-pressure side heat exchanger 44b of the internal heat
exchanging device 44 constitutes the second external refrigerant
circuit 62, which uses a part of the refrigerant passage of the
first external refrigerant circuit 41 in common. Therefore, the
cooling/heating switching valve 71 has a bypass passage 71a that
bypasses the indoor heat exchanger 46 in the first external
refrigerant circuit 41, and the cooling/heating switching valve 71
and the controller 51 constitute control means of the external
refrigerant circuit. It should be noted that the controller 51
switches the cooling/heating switching valve 71 to the
non-air-conditioning position on condition that the discharge
displacement of the compressor C is minimized.
[0080] The present embodiment has the same effects as the effects
(2) to (5) of the above-described first embodiment and additionally
has the following effects.
[0081] (1) In the state of the minimum discharge displacement of
the compressor C, the external refrigerant circulation via the
second external refrigerant circuit 62 is executed at all times,
and the circulating refrigerant and lubricating oil are cooled by
the heat radiation of the pipe constituting the second external
refrigerant circuit 62 and the internal heat exchanging device 44
(low-pressure side heat exchanger 44b). Thus, the compressor C does
not fall into thermally severe conditions. Further, since the
second external refrigerant circuit 62 does not pass through the
indoor heat exchanger 46, even if the refrigerant flows in the
circuit 62, it does not affect the air-conditioning. Therefore, the
components of the compressor C can be prevented from falling into
thermally severe conditions without executing unnecessary
air-conditioning. As a result, the durability of the compressor C
can be improved. Further, the use of carbon dioxide that exhibits
significantly higher pressure than chlorofluorocarbon refrigerant,
as a refrigerant can be easily realized.
[0082] (2) By adding a port to the cooling/heating switching valve
71 for switching the cooling/heating, the first external
refrigerant circuit 41 and the second external refrigerant circuit
62 are allowed to be open or closed (switched). Thus, an exclusive
switching valve for switching each external refrigerant circuit 41
and 62 is not needed and the circuit structure can be
simplified.
[0083] Further, the following embodiments may be performed in a
scope, which does not depart from the object of the present
invention.
[0084] In the first or third embodiment, the bypass control valve
63 may be formed by a differential pressure valve that opens or
closes the bypass passage 61 in accordance with the difference
between the discharge pressure and the suction pressure. In this
case, the bypass control valve 63 shuts off the bypass passage 61
under the circumstances where the pressure difference is a
predetermined value or less, and when the pressure difference
exceeds the predetermined value, the bypass passage 61 is
opened.
[0085] In the second embodiment, the bypass control valve 65 maybe
changed to open or close the bypass passage 61 according to the
housing temperature of the compressor C. For example, a sensing
member (bimetal) 65a of the bypass control valve 65 is disposed to
contact the housing of the compressor C outside the bypass passage
61, and the deformation of the sensing member 65a due to
fluctuation of the housing temperature is mechanically transmitted
to the valve body portion 65b provided in the bypass passage
61.
[0086] Further, in the second embodiment, the bypass control valve
65 may be changed to open or close the bypass passage 61 according
to the outside air temperature (a physical quantity that influences
on the heat-generation state of the compressor C). For example, a
sensing member (bimetal) 65a of the bypass control valve 65 may be
disposed to be exposed to the outside air, and the deformation of
the sensing member 65a due to fluctuation of the outside air
temperature may be mechanically transmitted to the valve body
portion 65b provided in the bypass passage 61.
[0087] In the fifth embodiment in FIGS. 6(a), 6(b) and 6(c), the
bypass control valves 63 and 65 as in, for example, the first and
second embodiments may be disposed on the bypass passage 71a in the
cooling/heating switching valve 71. By this setting, the same
effects as the effect (6) in the above-described first embodiment
can be obtained.
[0088] In each embodiment described above, the first external
refrigerant circuit 41 and the second external refrigerant circuit
62 may be respectively formed by an independent circuit and the
refrigerant passages (equipment such as a pipe and a heat
exchanger) need not be shared. In this case, when an exclusive heat
exchanger is provided on the second external refrigerant circuit
62, the cooling effects of circulating refrigerant and lubricating
oil in the circuit 62 are enhanced.
[0089] The present invention may be embodied in a vehicular air
conditioner using a fixed displacement type compressor. In this
case, for example, the first external refrigerant circuit is shut
off and the second external refrigerant circuit is opened when
cooling is unnecessary.
[0090] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein, but may be modified
within the scope and equivalence of the appended claims.
* * * * *