U.S. patent application number 13/980391 was filed with the patent office on 2013-11-14 for cooling apparatus.
This patent application is currently assigned to NIPPON SOKEN, INC.. The applicant listed for this patent is Yuki Jojima, Yoshiaki Kawakami, Yuichi Ohno, Kousuke Sato, Eizo Takahashi, Kazuhide Uchida. Invention is credited to Yuki Jojima, Yoshiaki Kawakami, Yuichi Ohno, Kousuke Sato, Eizo Takahashi, Kazuhide Uchida.
Application Number | 20130298591 13/980391 |
Document ID | / |
Family ID | 45571565 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130298591 |
Kind Code |
A1 |
Ohno; Yuichi ; et
al. |
November 14, 2013 |
COOLING APPARATUS
Abstract
A cooling apparatus that cools an HV appliance heat source
includes: a compressor for circulating a coolant; a condenser for
condensing the coolant; an expansion valve that decompresses the
coolant that has been condensed by the condenser; an evaporator for
evaporating the coolant that has been decompressed by the expansion
valve; and a coolant passageway through which the coolant that
moves from an outlet of the condenser toward an inlet of the
expansion valve flows. The coolant passageway includes a
passageway-forming portion that forms a portion of the coolant
passageway. The cooling apparatus further includes a coolant
passageway that is disposed in parallel with the passageway-forming
portion, and that circulates the coolant via the HV appliance heat
source.
Inventors: |
Ohno; Yuichi; (Nishio-shi,
JP) ; Uchida; Kazuhide; (Hamamatsu-shi, JP) ;
Kawakami; Yoshiaki; (Nagoya-shi, JP) ; Jojima;
Yuki; (Nagoya-shi, JP) ; Takahashi; Eizo;
(Chiryu-shi, JP) ; Sato; Kousuke; (Toyota-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ohno; Yuichi
Uchida; Kazuhide
Kawakami; Yoshiaki
Jojima; Yuki
Takahashi; Eizo
Sato; Kousuke |
Nishio-shi
Hamamatsu-shi
Nagoya-shi
Nagoya-shi
Chiryu-shi
Toyota-shi |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
NIPPON SOKEN, INC.
Nishio
JP
TOYOTA JIDOSHA KABUSHIKI KAISHA
Toyota-shi
JP
|
Family ID: |
45571565 |
Appl. No.: |
13/980391 |
Filed: |
January 27, 2012 |
PCT Filed: |
January 27, 2012 |
PCT NO: |
PCT/IB12/00120 |
371 Date: |
July 18, 2013 |
Current U.S.
Class: |
62/426 ;
62/498 |
Current CPC
Class: |
B60H 2001/00307
20130101; F25B 1/00 20130101; B60H 1/00278 20130101; B60H 2001/3288
20130101; B60H 1/323 20130101 |
Class at
Publication: |
62/426 ;
62/498 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2011 |
JP |
2011-022821 |
Claims
1. A cooling apparatus that cools a heat generation source,
comprising: a compressor that circulates a coolant; a condenser
that condenses the coolant; a decompressor that decompresses the
coolant that has been condensed by the condenser; an evaporator
that evaporates the coolant that has been decompressed by the
decompressor; a first passageway through which the coolant that
moves from an outlet of the condenser toward an inlet of the
decompressor flows, and which includes a passageway-forming portion
that forms a portion of the first passageway, and a second
passageway which is connected in parallel with the
passageway-forming portion, and which is provided with the heat
generation source, and in which the coolant flows via the heat
generation source.
2. The cooling apparatus according to claim 1, further comprising a
flow control valve that is disposed on the passageway-forming
portion and that adjusts amount of flow of the coolant flowing
through the passageway-forming portion and the amount of flow of
the coolant flowing through the second passageway.
3. The cooling apparatus according to claim 1, further comprising:
a third passageway through which the coolant that moves from an
outlet of the compressor toward an inlet of the condenser flows;
and a communication passageway that provides communication between
the third passageway and a downstream side of the second passageway
relative to the heat generation source.
4. The cooling apparatus according to claim 3, further comprising a
switching valve that switches state of communication between the
downstream side of the second passageway relative to the heat
generation source and each of the first passageway and the third
passageway.
5. The cooling apparatus according to claim 3, wherein the heat
generation source is disposed below the condenser.
6. The cooling apparatus according to claim 1, further comprising
another condenser disposed on the first passageway, wherein the
passageway-forming portion is provided between the condenser and
the another condenser.
7. The cooling apparatus according to claim 6, wherein the
condenser is higher in heat release capability of releasing heat
from the coolant than the another condenser.
8. The cooling apparatus according to claim 3, further comprising a
fan that blows air to the condenser.
9. A cooling apparatus that cools a heat generation source,
comprising: a compressor that circulates a coolant on a circulation
path; a condenser that condenses the coolant on the circulation
path; a decompressor that decompresses, on the circulation path,
the coolant that has been condensed by the condenser; an evaporator
that evaporates, on the circulation path, the coolant that has been
decompressed by the decompressor; a first passageway which is a
portion of the circulation path, and through which the coolant that
moves from an outlet of the condenser toward an inlet of the
decompressor flows, and which includes a passageway-forming portion
as a portion of the first passageway; and a second passageway which
is connected in parallel with the passageway-forming portion, and
which is provided with the heat generation source, and in which the
coolant flows via the heat generation source.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a cooling apparatus and, more
particularly, to a cooling apparatus that cools a heat generation
source by using a vapor compression type refrigeration cycle.
[0003] 2. Description of Related Art
[0004] In recent years, electric motor-driven vehicles, such as
hybrid vehicles, fuel cell vehicles, electric vehicles, etc., are
drawing attention as a measure for environmental problems. In those
vehicles, electrical appliances, such as electric motors,
generators, inverter, converters, batteries, etc., generate heat in
association with receiving or supplying electric power. Therefore,
these electrical appliances need to be cooled.
[0005] Japanese Patent Application Publication No. 2000-73763
(JP-A-2000-73763) discloses a cooling apparatus for a hybrid
vehicle which includes a first cooling circuit that cools an engine
cylinder head and a traction electric motor selectively or
simultaneously, a second cooling circuit that cools an engine
cylinder block, and a third cooling circuit that cools a
heavy-current system control unit that drives and controls the
traction motor.
[0006] The cooling apparatus described in Japanese Patent
Application
[0007] Publication No. 2000-73763 (JP-A-2000-73763) cools
electrical component parts by using a system that circulates a
cooling liquid between a heating element and a radiator, as in an
ordinary vehicle in which only the engine is cooled. Such a system
requires that a radiator for cooling the electrical component parts
be newly provided, and therefore has a problem of low
vehicle-mountability.
[0008] Therefore, there has been proposed a technology of cooling a
heating element by utilizing a vapor compression type refrigeration
cycle that is employed in a vehicle air-conditioner apparatus. For
example, Japanese Patent Application Publication No. 2007-69733
(JP-A-2007-69733) discloses a system in which a heat exchanger that
performs heat exchange with an air for use for air-conditioning and
a heat exchanger that performs heat exchange with a heating element
are disposed in parallel in a coolant passageway extending from an
expansion valve to a compressor, and in which the heating element
is cooled by utilizing the coolant for the air-conditioner
apparatus. Besides, Japanese Patent Application Publication No.
2005-90862 (JP-A-2005-90862) discloses a cooling system in which a
bypass passageway that bypasses a decompressor, an evaporator and a
compressor of a refrigeration cycle for the air-conditioning is
provided with heating element-cooling means for cooling a heating
element.
[0009] In the above-described cooling apparatuses disclosed in
Japanese Patent Application Publication No. 2007-69733
(JP-A-2007-69733) and Japanese Patent Application Publication No.
2005-90862 (JP-A-2005-90862), a cooling path for cooling heat
generation sources, such as electrical appliances and the like, are
incorporated into the vapor compression type refrigeration cycle,
and when the heat generation sources are cooled, the entire amount
of the coolant in the refrigeration cycle is introduced into the
cooling path provided for cooling the heat generation sources.
Therefore, the related-art apparatuses have problems of the
over-cooling of a heat generation source, increased pressure loss
in association with passage of the coolant, increased electric
power consumption of the compressor, among other problems.
SUMMARY OF THE INVENTION
[0010] The invention provides a cooling apparatus that is able to
prevent over-heating of a heat generation source and makes it
possible to reduce the pressure loss and reduce the electric power
consumption of the compressor.
[0011] A cooling apparatus of a first aspect of the invention
relates to a cooling apparatus that cools a heat generation source.
This cooling apparatus includes: a compressor that circulates a
coolant; a condenser that condenses the coolant; a decompressor
that decompresses the coolant that has been condensed by the
condenser; an evaporator that evaporates the coolant that has been
decompressed by the decompressor; a first passageway through which
the coolant that moves from an outlet of the condenser toward an
inlet of the decompressor flows and which includes a
passageway-forming portion that forms a portion of the first
passageway; and a second passageway which is connected in parallel
with the passageway-forming portion, and which is provided with the
heat generation source, and in which the coolant flows via the heat
generation source.
[0012] The cooling apparatus may further include a flow control
valve that is disposed on the passageway-forming portion and that
adjusts amount of flow of the coolant flowing through the
passageway-forming portion and the amount of flow of the coolant
flowing through the second passageway.
[0013] The cooling apparatus may further include: a third
passageway through which the coolant that moves from an outlet of
the compressor toward an inlet of the condenser flows; and a
communication passageway that provides communication between the
third passageway and a downstream side of the second passageway
relative to the heat generation source. The cooling apparatus may
further include a switching valve that switches state of
communication between the downstream side of the second passageway
relative to the heat generation source and each of the first
passageway and the third passageway. In the cooling apparatus, the
heat generation source may be disposed below the condenser.
[0014] The cooling apparatus may further include another condenser
disposed on the first passageway, and the passageway-forming
portion may be provided between the condenser and the another
condenser. In the cooling apparatus, the condenser may be higher in
heat release capability of releasing heat from the coolant than the
another condenser
[0015] The cooling apparatus may further include a fan that blows
air to the condenser.
[0016] A cooling apparatus of a second aspect of the invention
relates to a cooling apparatus that refrigerates a heat generation
source. This cooling apparatus includes: a compressor that
circulates a coolant on a circulation path; a condenser that
condenses the coolant on the circulation path; a decompressor that
decompresses, on the circulation path, the coolant that has been
condensed by the condenser; an evaporator that evaporates, on the
circulation path, the coolant that has been decompressed by the
decompressor; a first passageway which is a portion of the
circulation path, and through which the coolant that moves from an
outlet of the condenser toward an inlet of the decompressor flows,
and which includes a passageway-forming portion as a portion of the
first passageway; and a second passageway which is connected in
parallel with the passageway-forming portion, and which is provided
with the heat generation source, and in which the coolant flows via
the heat generation source.
[0017] According to the cooling apparatuses of the first and second
aspects of the invention, the over-cooling of the heat generation
source can be prevented, and the pressure loss and the electric
power consumption of the compressor can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0019] FIG. 1 is a schematic diagram showing a construction of a
cooling apparatus in accordance with a first embodiment of the
invention;
[0020] FIG. 2 is a Mollier diagram showing states of a coolant in a
vapor compression type refrigeration cycle in the first
embodiment;
[0021] FIG. 3 is a diagram schematically showing a control of the
opening degree of a flow control valve;
[0022] FIG. 4 is a schematic diagram showing a construction of a
cooling apparatus in accordance with a second embodiment of the
invention;
[0023] FIG. 5 is a Mollier diagram showing states of a coolant in a
vapor compression type refrigeration cycle in the second
embodiment;
[0024] FIG. 6 is a schematic diagram showing a construction of a
cooling apparatus in accordance with a third embodiment of the
invention;
[0025] FIG. 7 is a schematic diagram showing the flow of the
coolant that cools an HV appliance heat source during the operation
of the vapor compression type refrigeration cycle;
[0026] FIG. 8 is a schematic diagram showing the flow of the
coolant that cools the HV appliance heat source during a stop of
the vapor compression type refrigeration cycle;
[0027] FIG. 9 is a schematic diagram showing a construction of a
cooling apparatus in accordance with a fourth embodiment of the
invention;
[0028] FIG. 10 is a schematic diagram showing a construction of a
cooling apparatus in accordance with a fifth embodiment of the
invention, and showing the flow of a coolant that cools an HV
appliance heat source while a vapor compression type refrigeration
cycle is in operation; and
[0029] FIG. 11 is a schematic diagram showing the cooling apparatus
of the fifth embodiment, and showing the flow of the coolant that
cools the HV appliance heat source during a stop of the vapor
compression type refrigeration cycle.
DETAILED DESCRIPTION OF EMBODIMENTS
[0030] Embodiments of the invention will be described hereinafter
with reference to the drawings. The same or like portions are
denoted by the same reference characters in the drawings, and will
not be repeatedly described below.
First Embodiment
[0031] FIG. 1 is a schematic diagram showing a construction of a
cooling apparatus 1 in accordance with a first embodiment of the
invention. As shown in FIG. 1, the cooling apparatus 1 includes a
vapor compression type refrigeration cycle 10. The vapor
compression type refrigeration cycle 10 is mounted in a vehicle for
the purpose of, for example, cooling the air in the cabin of the
vehicle. The air-cooling through the use of the vapor compression
type refrigeration cycle 10 is performed, for example, in the case
where a switch for the air-cooling is turned on, or in the case
where an automatic control mode of automatically adjusting the
temperature inside the cabin of the vehicle so that the cabin
temperature becomes equal to a set temperature has been selected
and where the temperature in the cabin is higher than the set
temperature.
[0032] The vapor compression type refrigeration cycle 10 includes a
compressor 12, a condenser 14, an expansion valve 16 as an example
of the decompressor, and an evaporator 18. The vapor compression
type refrigeration cycle 10 also includes: a coolant passageway 21
as a third passageway that provides communication between the
compressor 12 and the condenser 14; a coolant passageway 22 as a
first passageway that provides communication between the condenser
14 and the expansion valve 16; a coolant passageway 23 that
provides communication between the expansion valve 16 and the
evaporator 18, and a coolant passageway 24 that provides
communication between the evaporator 18 and the compressor 12. The
vapor compression type refrigeration cycle 10 is constructed of the
compressor 12, the condenser 14, the expansion valve 16 and the
evaporator 18 that are linked by the coolant passageways 21 to
24.
[0033] The compressor 12 operates by using as a power source an
electric motor or an engine mounted in the vehicle, and
adiabatically compresses a coolant gas to a superheated coolant
gas. The compressor 12, when in operation, sucks and compresses a
gas-phase coolant that flows from the condenser 18 through the
coolant passageway 24, and discharges the compressed coolant into
the coolant passageway 21. The compressor 12 circulates the coolant
in the vapor compression type refrigeration cycle 10 by discharging
the coolant into the coolant passageway 21.
[0034] The condenser 14 causes the superheated coolant gas
compressed by the compressor 12 to isobarically release heat to an
external medium, and thereby changes it into a coolant liquid. The
gas-phase coolant discharged from the compressor 12 condenses
(liquefies) in the condenser 14 as it cools by releasing heat to
the surroundings. The condenser 14 includes a tube that conveys the
coolant, and fins for performing heat exchange between the coolant
flowing within the tube and the air around the condenser 14. The
condenser 14 performs heat exchange between the coolant and cooling
wind that is supplied by natural ventilation that is caused by the
traveling of the vehicle. Due to the heat exchange performed by the
condenser 14, the temperature of the coolant drops and the coolant
liquefies.
[0035] Specifications of the condenser 14 (i.e., the size or heat
release capability of the condenser 14) are determined so that the
temperature of the liquid-phase coolant having passed through the
condenser 14 is lower than a temperature that is needed for the
air-cooling of the cabin. The specifications of the condenser 14
are determined so as to provide an amount of heat release that is
larger than that of a condenser provided in a vapor compression
type refrigeration cycle that does not cool an HV appliance heat
source 30 (described later) by the amount of heat that the coolant
is assumed to receive from the HV appliance heat source 30. The
cooling apparatus 1 equipped with the condenser 14 having the
foregoing specifications is able to properly cool the HV appliance
heat source 30 while maintaining the capability of air-cooling the
cabin of the vehicle, without a need to increase the power of the
compressor 12.
[0036] The expansion valve 16 jets from small holes the
high-pressure liquid-phase coolant that flows in the coolant
passageway 22, so that the coolant expands and changes into a
low-temperature and low-pressure atomized coolant. The expansion
valve 16 changes the coolant liquid condensed by the condenser 14
into a wet vapor in a gas-liquid mixture state through
decompression. Incidentally, the decompressor for decompressing the
coolant liquid that flows in the coolant passageway 22 is not
limited to the expansion valve 16 that throttles or regulates the
flow and causes expansion of the coolant, but may also be capillary
tubes.
[0037] The evaporator 18 allows the atomized coolant flowing
therein to vaporize, and therefore absorbs heat from the ambient
air that is introduced so as to contact the evaporator 18. Using
the coolant decompressed by the expansion valve 16, the evaporator
18 obtains the heat of vaporization needed for the wet vapor of the
coolant to vaporize to become a coolant gas from the air in the
cabin of the vehicle as a part to be cooled, and thereby performs
the air-cooling of the cabin of the vehicle. The cooling of air in
the cabin of the vehicle is carried out as the air whose
temperature has dropped due to the heat absorption to the
evaporator 18 is returned into the cabin of the vehicle. The
coolant in the evaporator 18 absorbs heat from the ambient and
therefore is heated.
[0038] The evaporator 18 includes a tube that conveys the coolant,
and fins for performing heat exchange between the coolant flowing
in the tube and the air around the evaporator 18. Within the tube,
the coolant in the wet-vapor state flows. When the coolant flows in
the tube, the coolant evaporates by absorbing heat from the air in
the cabin of the vehicle as evaporative latent heat through the
fins, and then becomes superheated vapor due to sensible heat. The
vaporized coolant then flows to the compressor 12 through the
coolant passageway 24. The compressor 12 compresses the coolant
that flows from the evaporator 18.
[0039] The coolant passageway 21 is a passageway for conveying the
coolant from the compressor 12 to the condenser 14. The coolant
flows from an outlet of the compressor 12 toward an inlet of the
condenser 14 through the coolant passageway 21. The coolant
passageway 22 is a passageway for conveying the coolant from the
condenser 14 to the expansion valve 16. The coolant flows from an
outlet of the condenser 14 toward an inlet of the expansion valve
16 through the coolant passageway 22. The coolant passageway 23 is
a passageway for conveying the coolant from the expansion valve 16
to the evaporator 18. The coolant flows from an outlet of the
expansion valve 16 toward an inlet of the evaporator 18 through the
coolant passageway 23. The coolant passageway 24 is a passageway
for conveying the coolant from the evaporator 18 to the compressor
12. The coolant flows from an outlet of the evaporator 18 toward an
inlet of the compressor 12 through the coolant passageway 24.
[0040] In the vapor compression type refrigeration cycle 10, the
coolant flows so as to pass a point A, a point B, a point C, a
point D and a point E shown in FIG. 1 in that order, and thus the
coolant circulates through the compressor 12, the condenser 14, the
expansion valve 16 and the evaporator 18. The coolant circulates in
the vapor compression type refrigeration cycle 10, passing through
a coolant circulation flow path in which the compressor 12, the
condenser 14, the expansion valve 16 and the evaporator 18 are
sequentially connected by the coolant passageways 21 to 24.
[0041] Incidentally, the coolant for use in the vapor compression
type refrigeration cycle 10 may be, for example, carbon dioxide, a
hydrocarbon, such as propane, isobutane, etc., ammonia, water,
etc.
[0042] The coolant passageway 22 that conveys the coolant flowing
from the condenser 14 toward the expansion valve 16 includes a
passageway-forming portion 26. The passageway-forming portion 26
forms a portion of the coolant passageway 22. The point C shown in
FIG. 1 indicates an upstream-side end portion of the
passageway-forming portion 26, that is, an end portion of the
passageway-forming portion 26 which is at a side close to the
condenser 14. The point D shown in FIG. 1 indicates a
downstream-side end portion of the passageway-forming portion 26,
that is, an end portion of the passageway-forming portion 26 which
is at a side close to the expansion valve 16.
[0043] The cooling apparatus 1 is equipped with another coolant
passageway that is connected in parallel with the
passageway-forming portion 26. This other passageway includes
coolant passageways 31 and 32 as a second passageway. The coolant
that flows through the coolant passageways 31 and 32 flows via the
HV (hybrid vehicle) appliance heat source 30 as a heat generation
source, and takes heat from the HV appliance heat source 30 and
therefore cools the HV appliance heat source 30. The coolant
passageway 31 is a passageway for conveying the coolant from the
point C to the HV appliance heat source 30. The coolant passageway
32 is a passageway for conveying the coolant from the HV appliance
heat source 30 to the point D. The coolant flows from the point C
toward the HV appliance heat source 30 through the coolant
passageway 31, and flows from the HV appliance heat source 30
toward the point D through the coolant passageway 32. The point C
is a branch point between the coolant passageway 22 and the coolant
passageway 31. The point D is a branch point between the coolant
passageway 22 and the coolant passageway 32.
[0044] The HV appliance heat source 30 includes electrical
appliances that generate heat due to giving or receiving electric
power. The electrical appliances include at least one of an
inverter for converting direct-current power to alternating-current
power, a motor-generator that is a rotary electric machine, a
battery that is an electricity storage device, a converter that
increases the voltage of a battery, a DC/DC converter for reducing
the voltage of a battery, etc. The battery is a secondary battery
such as a lithium-ion battery, a nickel metal hydride battery, etc.
A capacitor may also be used instead of the battery.
[0045] FIG. 2 is a Mollier diagram showing states of the coolant in
the vapor compression type refrigeration cycle 10 in the first
embodiment. In FIG. 2, the horizontal axis shows the specific
enthalpy (unit: kJ/kg) of the coolant, and the vertical axis shows
the absolute pressure (unit: MPa) of the coolant. A curve in the
diagram is a combination of a saturation vapor line and a
saturation liquid line. FIG. 2 also shows thermodynamic states of
the coolant at various points (i.e., the points A, B, C, D and E)
in the vapor compression type refrigeration cycle 10 in which the
coolant flows from the coolant passageway 22 extending from the
outlet of the condenser 14 into the coolant passageway 31 via the
point C, cools the HV appliance heat source 30, and returns
therefrom through the coolant passageway 32, via the point D, into
the coolant passageway 22 extending to the inlet of the expansion
valve 16.
[0046] As shown in FIG. 2, the coolant in the superheated vapor
state having been sucked into the compressor 12 (point A) is
adiabatically compressed along an isoline of specific entropy by
the compressor 12. As the coolant is compressed, the pressure and
the temperature of the coolant increase so that the coolant becomes
a high-temperature and high-pressure superheated vapor with a large
degree of superheat (point B). Then, the coolant flows to the
condenser 14. The high-pressure coolant vapor, after entering the
condenser 14, is cooled in the condenser 14 so that the coolant
isobarically changes from the superheated vapor to a dry saturated
vapor, and gradually liquefies so as to become a wet vapor in the
gas-liquid mixture state while releasing latent condensation heat.
Then, as the entire amount of the coolant condenses, the coolant
becomes a saturated liquid, and then releases sensible heat to
become a supercooled liquid (point C).
[0047] The liquefied coolant flows from the point C into the HV
appliance heat source 30 through the coolant passageway 31, and
cools the HV appliance heat source 30. Due to the heat exchange
between the coolant and the HV appliance heat source 30, the degree
of supercooling lessens. That is, the temperature of the coolant in
the supercooled liquid state rises and approaches a saturation
temperature of the liquid coolant (point D). After that, the
coolant flows into the expansion valve 16. At the expansion valve
16, the coolant in the supercooled liquid state is throttled and
expanded, so that while the specific enthalpy remains unchanged,
the temperature and the pressure of the coolant drop, resulting in
a wet vapor in a low-temperature and low-pressure gas-liquid mixed
state (point E).
[0048] The coolant in the wet-vapor state having come out of the
expansion valve 16 then enters the evaporator 18, in which the
coolant absorbs heat from outside as evaporative latent heat so as
to isobarically evaporate to become a dry saturated vapor.
Furthermore, the temperature of the coolant vapor further rises due
to sensible heat to become a superheated vapor (point A), and then
is sucked into the compressor 12.
[0049] Following this cycle, the coolant continuously repeats the
changes in state in which it is compressed, condensed,
throttled-expanded, and evaporated.
[0050] Incidentally, although in the foregoing description of the
vapor compression type refrigeration cycle, the theoretical
refrigeration cycle is described, it is a matter of course that in
the vapor compression type refrigeration cycle 10 in real it is
necessary to consider the loss related to the compressor 12, and
the pressure loss and the heat loss of the coolant.
[0051] When the vapor compression is in operation, the coolant in
the evaporator 18 absorbs heat of vaporization from the air in the
cabin of the vehicle, and thus carrying out the air-cooling of the
cabin. Moreover, the high-pressure liquid coolant from the
condenser 14 forks at the point C, and a portion of the coolant
flows to the HV appliance heat source 30, and undergoes heat
exchange with the HV appliance heat source 30 and therefore cools
the HV appliance heat source 30. The cooling apparatus 1 cools the
HV appliance heat source 30, which is a heat generation source
mounted in the vehicle, by utilizing the vapor compression type
refrigeration cycle 10 provided for the air-conditioning of the
cabin of the vehicle.
[0052] As paths that convey the coolant from the outlet of the
condenser 14 toward the inlet of the expansion valve 16, the
coolant passageway 31 and 32 that is a path that passes via the HV
appliance heat source 30 and the passageway-forming portion 26 that
is a path that does not pass via the HV appliance heat source 30
are provided in parallel. Therefore, only a portion of the coolant
that flows out of the condenser 14 flows to the HV appliance heat
source 30. An amount of the coolant that is needed in order to cool
the HV appliance heat source 30 is caused to flow through the
coolant passageways 31 and 32, so that the HV appliance heat source
30 is appropriately cooled.
[0053] Therefore, the over-cooling of the HV appliance heat source
30 can be prevented. Since not the entire amount of the coolant
flows to the HV appliance heat source 30, the pressure loss related
to the passage of the coolant through the coolant passageways 31
and 32 can be reduced, and accordingly the electric power that
needs to be consumed in order to operate the compressor 12 for
circulating the coolant can be reduced.
[0054] The coolant is cooled in the condenser 14 until it becomes a
supercooled liquid. Then, the coolant receives sensible heat from
the HV appliance heat source 30, and is thereby heated to a
temperature that is slightly below the saturation temperature.
After that, as the coolant passes through the expansion valve 16,
the coolant becomes a low-temperature and low-pressure wet vapor.
At the outlet of the expansion valve 16, the coolant has a
temperature and a pressure that are basically needed for the
air-cooling of the cabin of the vehicle. As for the condenser 14,
its heat release capability is determined to such a degree as to
allow the coolant to be sufficiently cooled.
[0055] If the low-temperature and low-pressure coolant having
passed through the expansion valve 16 is used to cool the HV
appliance heat source 30, the capability of the evaporator 18 to
cool the air in the cabin decreases, and the air-cooling capability
for the cabin declines. In the cooling apparatus 1 in this
embodiment, on the other hand, the coolant is cooled to a
sufficiently supercooled state in the condenser 14, and the
high-pressure coolant at the outlet of the condenser 14 is used to
cool the HV appliance heat source 30. Therefore, the HV appliance
heat source 30 can be cooled without affecting the air-cooling
capability of cooling the air in the cabin. Incidentally, it is
desirable that the temperature needed in order to cool the HV
appliance heat source 30 be at least lower than an upper-limit
value of a temperature range that is targeted as the temperature
range of the HV appliance heat source 30.
[0056] Referring back to FIG. 1, the cooling apparatus 1 is
equipped with an engine cooling system 40 for cooling the engine
mounted in the vehicle. The engine cooling system 40 includes an
engine 41 for generating drive force of the vehicle, a radiator 42
that carries out heat exchange between cooling wind and a cooling
liquid, a pump 43 that circulates the cooling liquid, and a
radiator fan 44 that delivers cooling wind to the radiator 42. The
engine cooling system 40 also includes a piping system 45 that
links the engine 41 and the radiator 42, and a piping system 46
that links the radiator 42 and the pump 43, and a piping system 47
that links the pump 43 and the engine 41.
[0057] When the pump 43 activates, the cooling liquid is sent from
the pump 43 to the engine 41 through the piping system 47. Due to
the heat exchange between the engine 41 and the cooling liquid, the
engine 41 cools and the temperature of the cooling liquid rises.
The cooling liquid whose temperature has risen is sent to the
radiator 42 through the piping system 45. Since the radiator fan 44
disposed adjacent to the radiator 42 is activated to blow air to
the radiator 42, the cooling liquid in the radiator 42 cools by
releasing heat to air. In the radiator 42 provided for cooling the
cooling liquid heated by the engine 41, heat exchange occurs
between the cooling liquid and the cooling wind that is produced by
activation of the radiator fan 44, so that the temperature of the
cooling liquid decreases. The cooling liquid having a reduced
temperature returns to the pump 43 through the piping system
46.
[0058] As shown in FIG. 1, the radiator 42 of the engine cooling
system 40 is disposed adjacent to the condenser 14 of the vapor
compression type refrigeration cycle 10. The condenser 14, the
radiator 42 and the radiator fan 44 are disposed in a line so that
the radiator 42 is interposed between the radiator fan 44 and the
condenser 14. The radiator fan 44 blows air to the radiator 42 to
cool the cooling liquid that circulates in the engine cooling
system 40, and simultaneously blows air to the condenser 14 and
thus air-cools the condenser 14. The cooling apparatus 1 further
includes the radiator fan 44 that blows air to the condenser
14.
[0059] Since the radiator fan 44 air-cools the condenser 14 by
blowing air thereto, the heat exchange between the coolant in the
condenser 14 and the cooling wind supplied by the radiator fan 44
occurs in addition to the heat exchange between the coolant and
fresh air stream introduced into the traveling vehicle. This
accelerates the heat exchange in the condenser 14, and effectively
lowers the temperature of the coolant and therefore liquefies the
coolant. Furthermore, this causes the coolant in the condenser 14
to efficiently release heat, so that the capability of the
condenser 14 to cool the coolant will improve. Therefore, the
efficiency of the air-cooling of the cabin of the vehicle performed
through the use of the vapor compression type refrigeration cycle
10 and the efficiency of the cooling of the HV appliance heat
source 30 through the use of the vapor compression type
refrigeration cycle 10 can be further improved.
[0060] Since the radiator fan 44 of the engine cooling system 40 is
used as a fan for air-cooling the condenser 14, there is no need to
add a new fan. Therefore, the heat release capability of the
condenser 14 can be improved without increasing the cost of the
cooling apparatus 1.
[0061] The cooling apparatus 1 is further equipped with a flow
control valve 28. The flow control valve 28 is provided on the
coolant passageway 22 that extends from the condenser 14 toward the
expansion valve 16. The flow control valve 28 is connected to the
passageway-forming portion 26 that forms a portion of the coolant
passageway 22. The flow control valve 28 arbitrarily adjusts the
amount of flow of the coolant that flows through the
passageway-forming portion 26 and the amount of flow of the coolant
that flows through the coolant passageways 31 and 32, by changing
the degree of opening of the valve 28 so as to increase or decrease
the pressure loss of the coolant that flows through the
passageway-forming portion 26.
[0062] For example, if the flow control valve 28 is completely
closed to a valve opening degree of 0%, the entire amount of the
coolant that flows out of the condenser 14 flows from the point C
into the coolant passageway 31. If the valve opening degree of the
flow control valve 28 is increased, the amount of flow of the
coolant that flows directly into the expansion valve 16 through the
passageway-forming portion 26, of the amount of flow of the coolant
that flows from the condenser 14 into the coolant passageway 22,
increases, and the amount of flow of the coolant that flows through
the coolant passageways 31 and 32 and that therefore cools the HV
appliance heat source 30 decreases. If the valve opening degree of
the flow control valve 28 is decreased, the amount of flow of the
coolant that flows directly into the expansion valve 16 through the
passageway-forming portion 26, of the amount of flow of the coolant
that flows from the condenser 14 into the coolant passageway 22,
decreases, and the amount of flow of the coolant that flows through
the coolant passageways 31 and 32 and that therefore cools the HV
appliance heat source 30 increases.
[0063] If the valve opening degree of the flow control valve 28 is
increased, the amount of flow of the coolant that cools the HV
appliance heat source 30 decreases, so that the capability of
cooling the HV appliance heat source 30 declines. If the valve
opening degree of the flow control valve 28 is decreased, the
amount of flow of the coolant that cools the HV appliance heat
source 30 increases, so that the capability of cooling the HV
appliance heat source 30 improves. Since the amount of the coolant
that flows to the HV appliance heat source 30 can be optimally
adjusted by using the flow control valve 28, the over-cooling of
the HV appliance heat source 30 can be certainly prevented, and, in
addition, the pressure loss related to the passage of the coolant
through the coolant passageways 31 and 32 and the electric power
consumption of the compressor 12 for circulating the coolant can be
certainly reduced.
[0064] An example of a control in accordance with the adjustment of
the valve opening degree of the flow control valve 28 will be
described below. FIG. 3 is a diagram schematically showing a
control of the opening degree of the flow control valve 28. In FIG.
3, the horizontal axis for graphs (A) to (D) shows time. The
vertical axis in the graph (A) shows the valve opening degree in
the case where the flow control valve 28 is an electric expansion
valve that uses a stepping motor. The vertical axis in the graph
(B) shows the valve opening degree in the case where the flow
control valve 28 is a temperature type expansion valve that
operates in the opening and closing direction in response to
changes in temperature. The vertical axis in the graph (C) shows
the temperature of the HV appliance heat source 30. The vertical
axis in the graph (D) shows the temperature difference between the
outlet and inlet of the HV appliance heat source 30.
[0065] As the coolant flows through the coolant passageways 31 and
32, the HV appliance heat source 30 is cooled. The adjustment of
the valve opening degree of the flow control valve 28 is performed,
for example, by monitoring the temperature of the HV appliance heat
source 30, or the temperature difference between the outlet
temperature and the inlet temperature of the HV appliance heat
source 30. For example, with reference to the graph (C), a
temperature sensor that continuously measures the temperature of
the HV appliance heat source 30 is provided, and the temperature of
the HV appliance heat source 30 is monitored. Alternatively, for
example, with reference to the graph (D), a temperature sensor that
measures the inlet temperature and the outlet temperature of the HV
appliance heat source 30 is provided, and the temperature
difference between the outlet and the inlet of the HV appliance
heat source 30 is monitored.
[0066] If the temperature of the HV appliance heat source 30
exceeds a target temperature or the temperature difference between
the outlet and the inlet of the HV appliance heat source 30 exceeds
a target temperature difference (e.g., 3 to 5.degree. C.), the
opening degree of the flow control valve 28 is decreased as shown
in the graphs (A) and (B). Since the amount of flow of the coolant
that flows to the HV appliance heat source 30 through the coolant
passageway 31 is increased by reducing the opening degree of the
flow control valve 28 as described above, the HV appliance heat
source 30 can be more effectively cooled. In consequence, the
temperature of the HV appliance heat source 30 will decline to
become equal to or less than the target temperature as shown in the
graph (C), or the temperature difference between the outlet and the
inlet of the HV appliance heat source 30 can be decreased to become
equal to or less than the target temperature difference as shown in
the graph (D).
[0067] In this manner, by optimally adjusting the valve opening
degree of the flow control valve 28, the amount of the coolant that
brings about the heat release capability that is needed in order to
keep the temperature of the HV appliance heat source 30 in an
appropriate temperature range can be secured, and thus the HV
appliance heat source 30 can be appropriately cooled. Therefore,
the occurrence of a trouble in which the HV appliance heat source
30 becomes overheated and damaged can be certainly curbed.
Second Embodiment
[0068] FIG. 4 is a schematic diagram showing a construction of a
cooling apparatus 1 in accordance with a second embodiment of the
invention. The cooling apparatus 1 of the second embodiment is
different from that of the first embodiment in that a condenser 15
as another condenser that is different from the condenser 14 is
disposed in the coolant passageway 22 that links the condenser 14
and the expansion valve 16.
[0069] The cooling apparatus 1 of the second embodiment is equipped
with the condenser 14 as a first condenser, and the condenser 15 as
a second condenser. Since the condenser 15 is provided, the coolant
passageway 22 is divided into a coolant passageway 22a on an
upstream side (a side closer to the condenser 14) of the condenser
15, and a coolant passageway 22b on a downstream side (a side
closer to the expansion valve 16) of the condenser 15. In the vapor
compression type refrigeration cycle 10, the high-pressure coolant
discharged from the compressor 12 is condensed by both the
condenser 14 and the condenser 15.
[0070] A passageway-forming portion 26 that forms a portion of the
coolant passageway 22 is provided in the coolant passageway 22a
between the condenser 14 and the condenser 15. A cooling system for
the HV appliance heat source 30 which includes the coolant
passageways 31 and 32 is disposed in parallel with the
passageway-forming portion 26. A path of the coolant flowing from
the condenser 14 directly to the condenser 15 and a path of the
coolant flowing from the condenser 14 to the condenser 15 via the
HV appliance heat source 30 are provided in parallel, and only a
portion of the coolant is caused to flow through the coolant
passageways 31 and 32. In this manner, the pressure loss occurring
when the coolant flows in the cooling system of the HV appliance
heat source 30 can be reduced.
[0071] FIG. 5 is a Mollier diagram showing states of the coolant in
a vapor compression type refrigeration cycle 10 in the second
embodiment. The horizontal axis in FIG. 5 shows the specific
enthalpy (unit: kJ/kg) of the coolant, and the vertical axis shows
the absolute pressure (unit: MPa) of the coolant. A curve in the
diagram is a combination of a saturation vapor line and a
saturation liquid line. FIG. 5 also shows thermodynamic states of
the coolant at various points (i.e., the points A, B, C, D, E and
F) in the vapor compression type refrigeration cycle 10 in which
the coolant flows from the coolant passageway 22a extending from
the outlet of the condenser 14 into the coolant passageway 31 via
the point C and cools the HV appliance heat source 30, and returns
therefrom through the coolant passageway 32, via the point D, into
the coolant passageway 22a extending to the inlet of the condenser
15.
[0072] The vapor compression type refrigeration cycle 10 in the
second embodiment is the same as that in the first embodiment,
except a system extending from the condenser 14 to the expansion
valve 16. That is, the states of the coolant from the point D to
the point B via the points E and A in the Mollier diagram shown in
FIG. 2 and the states of the coolant from the point F to the point
B via the points E and A in the Mollier diagram shown in FIG. 5 are
the same. Therefore, the states of the coolant from the point B to
the point F, which are peculiar to the vapor compression type
refrigeration cycle 10 of the second embodiment, will be described
below.
[0073] The coolant in the high-temperature and high-pressure
superheated vapor state having been adiabatically compressed by the
compressor 12 (point B) is cooled by the condenser 14. The coolant
isobarically releases sensible heat to change from the superheated
vapor to a dry saturated vapor, and gradually liquefies to become a
wet vapor in a gas-liquid mixture state while releasing latent
condensation heat. Then, the entire amount of the coolant condenses
to become a saturated liquid (point C).
[0074] The coolant in the saturated liquid state having flown out
of the condenser 14 flows from the point C to the HV appliance heat
source 30 through the coolant passageway 31. The HV appliance heat
source 30 releases heat to the coolant that has passed through the
condenser 14 and therefore has been condensed by the condenser 14.
Thus, the HV appliance heat source 30 is cooled. Due to the heat
exchange with the HV appliance heat source 30, the coolant is
heated, so that the degree of dryness of the coolant increases. The
coolant partly vaporizes by receiving latent heat from the HV
appliance heat source 30, and thus becomes a wet vapor in which the
saturated liquid and the saturated vapor are mixed (point D).
[0075] After that, the coolant flows into the condenser 15. The wet
vapor of the coolant is re-condensed by the condenser 15. As the
entire amount of the coolant condenses, the coolant becomes a
saturated liquid, and then becomes a supercooled liquid (point F)
that is supercooled by releasing sensible heat. After that, as the
coolant passes through the expansion valve 16, the coolant becomes
a low-temperature and low-pressure wet vapor (point E).
[0076] Because the condenser 15 sufficiently cools the coolant, the
coolant at the outlet of the expansion valve 16 has a temperature
and a pressure that are basically needed in order to air-cool the
cabin of the vehicle. Therefore, the amount of heat that the
coolant receives from outside at the time of evaporating in the
evaporator 18 can be made sufficiently large. Thus, since the heat
release capability of the condenser 15 that allows the sufficient
cooling of the coolant is set, the HV appliance heat source 30 can
be cooled without affecting the air-cooling capacity of cooling the
air in the cabin. Hence, both the cooling capacity for the HV
appliance heat source 30 and the air-cooling capacity for the cabin
can be certainly secured.
[0077] In the vapor compression type refrigeration cycle 10 in the
first embodiment, the condenser 14 is disposed between the
compressor 12 and the expansion valve 16, so that the condenser 14
needs to cool the coolant further from the saturated liquid state
until the coolant has a predetermined degree of supercooling. If
the coolant in the supercooled liquid state is cooled, the
temperature of the coolant approaches the atmosphere temperature
and therefore the cooling efficiency for the coolant declines, so
that the capacity of the condenser 14 needs to be increased. This
will result in a problem of the condenser 14 having an increased
size and becoming disadvantageous as a component of the cooling
apparatus 1 that is to be mounted in a vehicle. On the other hand,
if the condenser 14 is reduced in size for the mountability in a
vehicle, the heat release capability of the condenser 14 also
reduces, so that there arises a risk of failing to achieve a
sufficiently low temperature of the coolant at the outlet of the
expansion valve 16 and therefore resulting in an insufficient
air-cooling capability for the cabin.
[0078] In contrast, in the vapor compression type refrigeration
cycle 10 in the second embodiment, the two condensers 14 and 15 are
disposed between the compressor 12 and the expansion valve 16, and
the cooling system for the HV appliance heat source 30 is provided
between the condenser 14 and the condenser 15. Therefore, the
condenser 14 needs only to cool the coolant to the saturated liquid
state as shown in FIG. 5. The coolant in the wet-vapor state that
has partly vapored by receiving evaporative latent heat from the HV
appliance heat source 30 is re-condensed in the condenser 15. The
coolant changes in state at a constant temperature until the
coolant in the wet-vapor state completely condenses to the
saturated liquid. The condenser 15 further cools the coolant
approximately to a degree of supercooling that is needed for the
air-cooling of the cabin of the vehicle. Therefore, in comparison
with the first embodiment, there is no need to increase the degree
of supercooling of the coolant, and the capacities of the
condensers 14 and 15 can be reduced. Hence, the sizes of the
condensers 14 and 15 can be reduced, making it possible to provide
the small-size cooling apparatus 1 that is advantageous in the
mounting in a vehicle.
[0079] The coolant that flows from the condenser 14 to the HV
appliance heat source 30 is heated by receiving heat from the HV
appliance heat source 30 when cooling the HV appliance heat source
30. If the coolant heated at the HV appliance heat source 30 should
vaporize, the amount of heat exchange between the coolant and the
HV appliance heat source 30 will decrease so that the HV appliance
heat source 30 cannot be sufficiently cooled, and the pressure loss
at the time of the coolant passing in the piping system will
increase. Therefore, it is desirable to sufficiently cool the
coolant in the condenser 14 to such a degree that the coolant will
not vaporize after cooling the HV appliance heat source 30.
[0080] Concretely, the state of the coolant at the outlet of the
condenser 14 is caused to be near the saturated liquid state.
Typically, at the outlet of the condenser 14, a state in which the
coolant is on the saturation liquid line is brought about. As
result of the result of the condenser 14 having a capability of
sufficiently cooling the coolant in this manner, the heat release
capability of releasing heat from the coolant in the condenser 14
is higher than the heat release capability of the condenser 15.
Since the condenser 14 having relatively large heat release
capability sufficiently cools the coolant, the coolant having
received heat from the HV appliance heat source 30 can be kept in
the wet-vapor state and therefore reduction of the amount of heat
exchange between the coolant and the HV appliance heat source 30
can be avoided, so that the HV appliance heat source 30 can be
sufficiently efficiently cooled. After the HV appliance heat source
30 is cooled, the coolant in the wet-vapor state is efficiently
re-cooled in the condenser 15 until the coolant is cooled to a
supercooled liquid state whose temperature is slightly below the
saturation temperature. Therefore, it is possible to provide the
cooling apparatus 1 that certainly has both the air-cooling
capability for the cabin and the cooling capability for the HV
appliance heat source 30.
Third Embodiment
[0081] FIG. 6 is a schematic diagram showing a construction of a
cooling apparatus 1 in accordance with a third embodiment of the
invention. The cooling apparatus 1 of the third embodiment is
different from that of the second embodiment, in having a
communication passageway 51.
[0082] Concretely, the communication passageway 51 provides
communication between the coolant passageway 21 that conveys the
coolant that flows from the outlet of the compressor 12 toward the
inlet of the condenser 14, and the coolant passageway 32 that is,
of the coolant passageways 31 and 32 that convey the coolant via
the HV appliance heat source 30, the one provided at the downstream
of the HV appliance heat source 30. The coolant passageway 32 is
provided with a switching valve 52 that switches the state of
communication between the coolant passageway 32 and the coolant
passageways 21 and 22. The switching valve 52 in the third
embodiment is a three-way valve 53. The coolant passageway 32 is
divided into a coolant passageway 32a at the upstream side of the
three-way valve 53 and a coolant passageway 32b at the downstream
side of the three-way valve 53.
[0083] By changing the open-closed state of the three-way valve 53,
the coolant flowing in the coolant passageway 32a after cooling the
HV appliance heat source 30 can be caused to flow to the condenser
15 through the coolant passageway 32b, or to flow to the condenser
14 through the coolant passageway 51. By switching the path of the
coolant through the use of the three-way valve 53 as an example of
the switching valve 52, the coolant, after cooling the HV appliance
heat source 30, can be arbitrarily selectively caused to flow
through one of the path to the expansion valve 16 through the
coolant passageways 32b and 22 and the path to the condenser 14
through the communication passageway 51 and the coolant passageway
21.
[0084] FIG. 7 is a schematic diagram showing the flow of the
coolant that cools the HV appliance heat source 30 during the
operation of the vapor compression type refrigeration cycle 10.
While the vapor compression type refrigeration cycle 10 is in
operation with the compressor 12 being driven, the valve opening
degree of the flow control valve 28 is adjusted so that a
sufficient amount of the coolant flows to the HV appliance heat
source 30. The three-way valve 53 is operated so as to cause the
coolant to flow from the HV appliance heat source 30 to the
expansion valve 16 via the condenser 15; thus, the path of the
coolant is selected so that the coolant flows in the entire cooling
apparatus 1. Therefore, the cooling capability of the vapor
compression type refrigeration cycle 10 can be secured, and the HV
appliance heat source 30 can be efficiently cooled.
[0085] FIG. 8 is a schematic diagram showing the flow of the
coolant that cools the HV appliance heat source 30 during a stop of
the vapor compression type refrigeration cycle 10. As shown in FIG.
8, when the compressor 12 is stopped and therefore the vapor
compression type refrigeration cycle 10 is stopped, the three-way
valve 53 is operated so as to circulate the coolant from the HV
appliance heat source 30 to the condenser 14, and the flow control
valve 28 is completely closed. By causing the coolant to flow
through the communication passageway 51, there is formed a closed
annular path in which the coolant flows from the condenser 14 to
the HV appliance heat source 30 through the coolant passageway 22a
and the coolant passageway 31 in that order, and returns from the
HV appliance heat source 30 to the condenser 14 through the coolant
passageway 32a, the communication passageway 51 and the coolant
passageway 21 in that order.
[0086] Through this annular path, the coolant can be circulated
between the condenser 14 and the HV appliance heat cycle 10 without
operating the compressor 12. The coolant, when cooling the HV
appliance heat source 30, evaporates by receiving evaporative
latent heat from the HV appliance heat source 30. The coolant vapor
vaporized at the HV appliance heat source 30 flows to the condenser
14 through the coolant passageway 32a, the communication passageway
51 and the coolant passageway 21 in that order. In the condenser
14, the coolant vapor is cooled to condense by fresh air stream
introduced into the traveling vehicle or the ventilation from the
radiator fan 44. The coolant liquid liquefied in the condenser 14
returns to the HV appliance heat source 30 through the coolant
passageways 22a and 31.
[0087] Thus, the annular path that extends via the HV appliance
heat source 30 and the condenser 14 forms a heat pipe in which the
HV appliance heat source 30 serves as a heating portion and the
condenser 14 serves as a cooling portion. Therefore, even when the
vapor compression type refrigeration cycle 10 is at a stop, that
is, even when the air-cooling for the vehicle is at a stop, the HV
appliance heat source 30 can be certainly cooled without a need to
activate the compressor 12. Since there is no need to always
operate the compressor 12 in order to cool the HV appliance heat
source 30, the electric power consumption of the compressor 12 can
be reduced and the fuel economy of the vehicle can be improved, and
in addition, the service life of the compressor 12 can be
increased, so that the reliability of the compressor 12 can be
improved.
[0088] FIGS. 7 and 8 show a ground surface 60. In a vertical
direction perpendicular to the ground surface 60, the HV appliance
heat source 30 is disposed below the condenser 14. In the annular
path that circulates the coolant between the condenser 14 and the
HV appliance heat source 30, the HV appliance heat source 30 is
disposed at a relatively low position, and the condenser 14 is
disposed at a relatively high position. That is, the condenser 14
is disposed at a higher position than the HV appliance heat source
30.
[0089] In this case, the coolant vapor vaporized due to the heating
by the HV appliance heat source 30 ascends in the annular path and
reaches the condenser 14, in which the coolant is cooled to
condense into the liquid coolant. The liquid coolant then descends
in the annular path by gravity, and returns to the HV appliance
heat source 30. That is, the HV appliance heat source 30, the
condenser 14 and the coolant path that links the HV appliance heat
source 30 and the condenser 14 form a thermo-siphon type heat pipe.
Since the formation of the heat pipe improves the efficiency of
heat transfer from the HV appliance heat source 30 to the condenser
14, the HV appliance heat source 30 can be further efficiently
cooled without adding power even when the vapor compression type
refrigeration cycle 10 is at a stop.
Fourth Embodiment
[0090] FIG. 9 is a schematic diagram showing a construction of a
cooling apparatus 1 in accordance with a fourth embodiment of the
invention. In comparison with the cooling apparatus 1 of the third
embodiment shown in FIG. 8, the cooling apparatus 1 of the fourth
embodiment has a check valve 55. The check valve 55 is disposed on
the coolant passageway 21 between the compressor 12 and the
condenser 14, more specifically, at a position on the coolant
passageway 21 which is to the compressor 12 side of the connecting
portion between the coolant passageway 21 and the communication
passageway 51. The check valve 55 allows the flow of the coolant in
the direction from the compressor 12 toward the condenser 14, and
prohibits the flow of the coolant in the opposite direction.
[0091] With this arrangement, a closed-loop path of the coolant in
which the coolant is circulated between the condenser 14 and the HV
appliance heat source 30 can be certainly formed by completely
closing the flow control valve 28 (to a valve opening degree of 0%)
and adjusting the three-way valve 53 so that the coolant flows from
the coolant passageway 32a to the communication passageway 51, but
does not flow to the coolant passageway 32b as shown in FIG. 9.
[0092] In the case where the check valve 55 is not provided, there
is a risk that the coolant that is to flow from the communication
passageway 51 to the coolant passageway 21 may flow to the
compressor 12 side. However, the provision of the check valve 55
certainly prohibits the flow of the coolant from the communication
passageway 51 to the compressor 12 side, so that it is possible to
prevent reduction of the cooling capability for the HV appliance
heat source 30 during a stop of the vapor compression type
refrigeration cycle 10 that employs the heat pipe formed by the
annular coolant path. Therefore, even when the air-cooling for the
cabin of the vehicle is at a stop, the HV appliance heat source 30
can be efficiently cooled.
[0093] Besides, in the case where, during a stop of the vapor
compression type refrigeration cycle 10, the amount of the coolant
in the closed-loop coolant path becomes insufficient, the coolant
can be supplied to the closed-loop path via the check valve 55 by
operating the compression 12 only for a short time. This will
increase the amount of the coolant in the closed-loop, and will
increase the amount of heat exchange process in the heat pipe.
Therefore, the amount of the coolant in the heat pipe can be
secured, so that it is possible to avoid an event in which the
cooling of the HV appliance heat source 30 becomes insufficient due
to insufficient amount of the coolant.
Fifth Embodiment
[0094] FIG. 10 is a schematic diagram showing a construction of a
cooling apparatus 1 in accordance with a fifth embodiment of the
invention. FIG. 10 shows the flow of the coolant that cools the HV
appliance heat source 30 while the vapor compression type
refrigeration cycle 10 is in operation. FIG. 11 is a schematic
diagram showing the cooling apparatus 1 of the fifth embodiment.
FIG. 11 shows the flow of the coolant that cools the HV appliance
heat source 30 during a stop of the vapor compression type
refrigeration cycle 10. In comparison with the construction shown
in FIGS. 7 and 8, the cooling apparatus 1 of the fifth embodiment
is provided with two valves 57 and 58 instead of the three-way
valve 53 as the switch valve 52.
[0095] As shown in FIG. 10, during the operation of the vapor
compression type refrigeration cycle 10, the valve 57 is fully
opened (to an opening valve degree of 100%) and the valve 58 is
completely closed (to an opening valve degree of 0%). In this
manner, the valve opening degree of the flow control valve 28 is
adjusted so that a sufficient amount of the coolant flows to the HV
appliance heat source 30. As a result, it is possible to cause the
coolant, after cooling the HV appliance heat source 30, to
certainly flow to the condenser 15 through the coolant passageways
32a, 32b and 22a. On the other hand, as shown in FIG. 11, when the
vapor compression type refrigeration cycle 10 is at a stop, the
valve 58 is fully opened, and the valve 57 is completely closed,
and furthermore the flow control valve 28 is completely closed. As
a result, there is formed an annular path that circulates the
coolant between the HV appliance heat source 30 and the condenser
14.
[0096] Thus, the switching valve 52 that switches the state of
communication between the coolant passageway 32 and the coolant
passageways 21 and 22 may be the three-way valve 53, or may also be
the pair of valves 57 and 58. In either case, both during the
operation of the vapor compression type refrigeration cycle 10 and
during the stop thereof, the HV appliance heat source 30 can be
efficiently cooled.
[0097] The valves 57 and 58 need only to have a simple structure
that is able to open and close a coolant passageway, and therefore
are inexpensive. The use of the two valves 57 and 58 instead of the
three-way valve 53 will provide a more inexpensive cooling
apparatus 1. On the other hand, the three-way valve 53 is
considered to take up a smaller space for installation than the two
valves 57 and 58. Therefore, the use of the three-way valve 53 will
provide a cooling apparatus 1 that is further reduced in size and
is therefore excellent in the vehicle mountability.
[0098] Incidentally, the first to fifth embodiments are described
above in conjunction with the cooling apparatuses 1 that each cool
an electrical appliance mounted in a vehicle, for example, the HV
appliance heat source 30. The electrical appliance is not limited
to the electrical appliances shown above as examples, such as
inverts, motor-generators, etc., but may be any electrical
appliance as long as the electrical appliance at least generates
heat when operated. In the case where the object to be cooled
includes a plurality of electrical appliances, it is desirable that
those electrical appliances have a common range of target
temperature for cooling. The range of target cooling temperature is
an appropriate temperature range as a temperature environment in
which the electrical appliances are operated.
[0099] Furthermore, the heat generation source to be cooled by the
cooling apparatus 1 in accordance with the invention is not limited
to the electrical appliances mounted in a vehicle, but may be any
appliance that generates heat, or a heat-generating portion of any
appliance.
[0100] While what are considered to be the preferred embodiments of
the invention have been described above, constructions of the
individual embodiments may be combined as appropriate. Besides, it
is to be understood that the embodiments disclosed herein are mere
illustration in all respects, and not restrictive at all. The scope
of the invention is shown not by the foregoing description but by
the appended claims, and is intended to encompass meanings
equivalent to the claims and all modifications and changes within
the scope of the invention.
[0101] The cooling apparatus of the invention is particularly
advantageously applicable to the cooling of an electrical appliance
that employs a vapor compression type refrigeration cycle for the
air-cooling of a cabin of a vehicle equipped with electrical
appliances such as a motor-generator, an inverter, etc., for
example, a hybrid vehicle, a fuel-cell vehicle, an electric
vehicle, etc.
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