WO2012090053A1

WO2012090053A1 - Cooling system

Info

Publication number: WO2012090053A1
Application number: PCT/IB2011/003155
Authority: WO
Inventors: Yoshiaki Kawakami; Yuki JOJIMA; Eizo Takahashi; Kousuke Sato; Yuichi Ono; Kazuhide Uchida
Original assignee: Toyota Jidosha Kabushiki Kaisha; Nippon Soken, Inc.
Priority date: 2010-12-28
Filing date: 2011-12-26
Publication date: 2012-07-05
Also published as: JP2012140060A

Abstract

A cooling system (10) includes: a compressor (20) that circulates refrigerant; a first condenser (40) that condenses the refrigerant; a second condenser (42) that is provided downstream of the first condenser (40); an evaporator (80) that uses the refrigerant from the second condenser (42) to cool a cabin of a vehicle; and a cooling portion (120) that is provided in a path of the refrigerant flowing from the first condenser (40) toward the second condenser (42) and that uses the refrigerant from the first condenser (40) to cool an electrical device.

Description

COOLING SYSTEM

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a cooling system for an electrical device equipped for a vehicle that uses an electrical rotating machine as a driving source and, more particularly, to a cooling system that uses an air-conditioning refrigeration cycle system to cool an electrical device.

2. Description of Related Art

[0002] In recent years, hybrid vehicles, fuel cell vehicles, electric vehicles, and the like, that run with driving force of a motor become a focus of attention as one of measures against environmental issues.

[0003] In such vehicles, electrical devices, such as a motor, a generator, an inverter, a converter and a battery, exchange electric power to generate heat, so these electrical devices need to be cooled. In this case, it is conceivable that, as in the case of a normal vehicle that uses only an engine, an additional cooling system is provided so as to circulate coolant between the electrical devices and a radiator; however, when such an additional cooling system is provided, an exclusive radiator needs to be provided, so mountability on the vehicle may decrease.

[0004] In light of such a problem, Japanese Patent Application Publication No. 2006-290254 (JP-A-2006-290254) describes a cooling system for a hybrid vehicle. The cooling system is able to improve assemblability, reduce cost and reduce size owing to commonality of components. The cooling system includes a compressor that is able to draw and compress gas refrigerant, a main condenser that may be cooled by ambient air for condensing high-pressure gas refrigerant, an evaporator that is able to cool a cooled medium by evaporating low-temperature liquid refrigerant, and first decompressing means. A heat exchanger that is able to absorb heat from a motor and second decompressing means are connected in parallel with the first decompressing means and the evaporator.

[0005] With the cooling system described in the above publication, assemblability is improved owing to commonality of components to thereby make it possible to reduce manufacturing cost. In addition, it is possible to reduce size.

[0006] However, when, as in case of the cooling system described in JP-A-2006-290254, two components, that is the evaporator and the heat exchanger that is able to absorb heat from the motor, are connected in parallel with each other, it is necessary to supply refrigerant to each of the evaporator and the heat exchanger and to decompress the refrigerant to perfect gas. Therefore, there is a problem that the power required of the compressor for cooling increases. In addition, there is a problem that fuel economy deteriorates when the size of the compressor increases and, in addition, mountability of the condenser deteriorates when the size of the condenser is increased in order to improve the power of the compressor.

SUMMARY OF THE INVENTION

[0007] The invention provides a cooling system that cools an electrical device without deteriorating power required of a compressor and mountability of the cooling system to a vehicle.

[0008] An aspect of the invention provides a cooling system that cools an electrical device equipped for a vehicle. The cooling system includes: a compressor that circulates refrigerant; a first condenser that condenses the refrigerant; a second condenser that is provided downstream of the first condenser; an evaporator that uses the refrigerant from the second condenser to cool a cabin of the vehicle; and a cooling portion that is provided in a path of the refrigerant flowing from the first condenser toward the second condenser and that uses the refrigerant from the first condenser to cool the electrical device. [0009] The cooling system may have a first passage that introduces the refrigerant from the first condenser to the cooling portion and a second passage that introduces the refrigerant from the cooling portion to the second condenser. The path of the refrigerant flowing from the first condenser toward the second condenser may pass through the first passage, the cooling portion and the second passage.

[0010] Furthermore, the first condenser and the second condenser may be integrally arranged. The first condenser and the second condenser may be separately arranged.

[0011] Furthermore, the first condenser may condense the refrigerant from the compressor into any one of a first state where the refrigerant is liquefied and a second state where the vaporized refrigerant and the liquefied refrigerant are mixed. The second condenser may decrease a temperature of the liquefied refrigerant.

[0012] Furthermore, the first condenser may condense the refrigerant into a state where a temperature of the refrigerant is lower than or equal to a temperature required to cool the electrical device. The second condenser may condense the refrigerant from the cooling portion into any one of a first state where the refrigerant is liquefied and a second state where the vaporized refrigerant and the liquefied refrigerant are mixed.

[0013] The cooling system may further include a valve that is provided between the second condenser and the evaporator, and that supplies the atomized refrigerant to the evaporator when the cabin of the vehicle is cooled.

[0014] According to the aspect of the invention, the cooling portion for cooling the electrical device is provided in the path of the refrigerant flowing from the first condenser to the second condenser to thereby make it possible to cool the electrical device using the liquid refrigerant flowing from the first condenser. Therefore, it is not necessary to decompress refrigerant into perfect gas at the cooling portion unlike the case of the evaporator, so it is not necessary to increase the power of the compressor as compared with when refrigerant supplied to the cooling portion is decompressed into perfect gas. As a result, it is possible to avoid increasing the size of the compressor or providing an exclusive pump for cooling the electrical device. Thus, it is possible to provide the cooling system that cools the electrical device without deteriorating power required of the compressor and mountability of the cooling system to the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

FIG. 1 is a view that shows the overall configuration of a cooling system according to an embodiment;

FIG. 2 is a view that shows an example of the internal structures of a first condenser and second condenser in the embodiment;

FIG. 3 is a graph for illustrating the operation of the cooling system according to the embodiment;

FIG. 4 is a view that shows the overall configuration of a cooling system according to an alternative embodiment to the embodiment; and

FIG. 5 is a view that shows an example of the internal structures of a first condenser and second condenser in an alternative embodiment to the embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0016] Hereinafter, an embodiment of the invention will be described with reference to the accompanying drawings. In the following description, like reference numerals denote the same components. The names and functions of them are also the same. Thus, the detailed description thereof is not repeated.

[0017] A cooling system 10 according to the present embodiment shown in FIG. 1 cools electrical devices equipped for a vehicle that uses an electrical rotating machine as a driving source. The vehicle that uses an electrical rotating machine as a driving source is, for example, an electric vehicle, a fuel cell vehicle or a hybrid vehicle.

[0018] In the present embodiment, the "electrical devices" are, for example, an inverter 122 for converting direct-current electric power to alternating-current electric power and a motor generator 124 that serves as the electrical rotating machine by way of example. In the following description, these electrical devices may be simply referred to as "electrical devices" where appropriate.

[0019] Note that the battery is a secondary battery, such as a lithium ion battery or a nickel metal hydride battery. A capacitor may be used instead of the battery.

[0020] In addition, when there are a plurality of electrical devices to be cooled, the plurality of electrical devices desirably have a common target temperature range for cooling. The target temperature range for cooling is an appropriate temperature range as a temperature environment in which the electrical devices are operated.

[0021] The cooling system 10 according to the present embodiment includes a compressor 20, a first condenser 40, a second condenser 42, an evaporator 80, an expansion valve 150, a cooling portion 120 and an electronic control unit (ECU) 400.

[0022] The cooling portion 120 is provided in the path of refrigerant flowing from the first condenser 40 to the second condenser 42, and uses refrigerant flowing from the first condenser 40 to cool the electrical devices.

[0023] Specifically, one end of a first connection passage 302 is connected to an outlet portion 46 of the first condenser 40. The other end of the first connection passage 302 is connected to the cooling portion 120. Refrigerant in the first condenser 40 flows to the cooling portion 120 via the first connection passage 302.

[0024] One end of a second connection passage 304 is connected to the cooling portion 120. The other end of the second connection passage 304 is connected to an inlet portion 48 of the second condenser 42. Refrigerant in the cooling portion 120 flows to the second condenser 42 via the second connection passage 304.

[0025] That is, the path of refrigerant flowing from the first condenser 40 to the second condenser 42 passes through the first connection passage 302, the cooling portion 120 and the second connection passage 304.

[0026] The evaporator 80 and the compressor 20 are connected by a third connection passage 306. The compressor 20 and the first condenser 40 are connected by a fourth connection passage 308. Furthermore, the second condenser 42 and the evaporator 80 are connected by a fifth connection passage 310.

[0027] The compressor 20 operates using a motor equipped for the vehicle as a driving source. During operation of the compressor 20, the compressor 20 draws and compresses gaseous refrigerant flowing from the evaporator 80 via the third connection passage 306 and discharges the compressed refrigerant to the fourth connection passage 308. The compressor 20 operates on the basis of a control signal CI from the ECU 400. Note that the compressor 20 may use an engine as a driving source.

[0028] The cabin of the vehicle is cooled using the evaporator 80, for example, when a switch for cooling is turned on. Alternatively, the cabin of the vehicle is cooled using the evaporator 80 when an automatic control mode in which the temperature of the cabin of the vehicle is automatically adjusted to a set temperature is selected and the temperature of the vehicle cabin is higher than the set temperature.

[0029] As shown in FIG. 2, the first condenser 40 and the second condenser 42 are integrally arranged. The integrally arranged first condenser 40 and second condenser 42 are, for example, provided next to an engine cooling radiator equipped for the vehicle, and exchange heat between refrigerant and running wind of the vehicle or cooling air supplied by a cooling fan.

[0030] The first condenser 40 dissipates heat from refrigerant compressed by the compressor 20 to condense (liquefy) refrigerant into any one of a first state where refrigerant flowing from the compressor 20 is liquefied and a second state where vaporized refrigerant (saturated vapor) and liquefied refrigerant (saturated liquid) are mixed.

[0031] The first condenser 40 includes a plurality of tubes 60 and a plurality of fins 62. The plurality of tubes 60 flow refrigerant. The plurality of fins 62 are used to exchange heat between refrigerant in the plurality of tubes 60 and air around the first condenser 40.

[0032] The plurality of tubes 60 are arranged in parallel with one another between the inlet portion 44 that introduces refrigerant from the compressor 20 and the outlet portion 46 that is connected to the cooling portion 120. Refrigerant introduced through the inlet portion 44 flows through the plurality of tubes 60 in a distributed manner.

[0033] The plurality of fins 62 each are arranged between the inlet portion 44 and the outlet portion 46 and arranged between and next to the adjacent two of the plurality of tubes 60. In each of the plurality of tubes 60, refrigerant is condensed by exchanging heat with air around the first condenser 40, passing through the fins 62. Refrigerant condensed in the first condenser 40 flows to the cooling portion 120 through the outlet portion 46.

[0034] The specifications of the first condenser 40 (that is, the size or heat dissipation performance of each of the tubes 60 and fins 62) are desirably determined so that at least the temperature of liquid refrigerant that has passed through the first condenser 40 is lower than the temperature required to cool the electrical devices. The temperature required to cool the electrical devices is desirably at least lower than the upper limit of a temperature range that is a target temperature range of the electrical devices.

[0035] In addition, the specifications of the first condenser 40 are desirably determined so that refrigerant comes into a state where gaseous refrigerant and liquid refrigerant are mixed or a state of liquid refrigerant having a small degree of supercooling at the outlet portion 46.

[0036] The second condenser 42 further cools refrigerant flowing through the cooling portion 120 to decrease (supercool) the temperature of the refrigerant. The second condenser 42 includes a plurality of tubes 66 and a plurality of fins 68. The plurality of tubes 66 flow refrigerant. The plurality of fins 68 are used to exchange heat between refrigerant in the plurality of tubes 66 and air around the second condenser 42.

[0037] The plurality of tubes 66 are arranged in parallel with one another between the inlet portion 48 and the outlet portion 50. The inlet portion 48 introduces refrigerant from the cooling portion 120. The outlet portion 50 is connected to the evaporator 80. Refrigerant introduced through the inlet portion 48 flows through the plurality of tubes 66 in a distributed manner. [0038] The plurality of fins 68 each are arranged between the inlet portion 48 and the outlet portion 50 and arranged between and next to the adjacent two of the plurality of tubes 66. In each of the plurality of tubes 66, refrigerant is cooled by exchanging heat with air around the second condenser 42, passing through the fins 68. Refrigerant cooled in the second condenser 42 flows to the evaporator 80 through the outlet portion 50.

[0039] The specifications of the second condenser 42 (that is, the size or heat dissipation performance of each of the tubes 66 and fins 68) are desirably determined so that at least the amount of heat dissipation until refrigerant passes through the cooling portion 120 in a predetermined outside air temperature environment is larger than or equal a predetermined amount.

[0040] Referring back to FIG. 1, the expansion valve 150 injects high-temperature and high-pressure liquid refrigerant, flowing through the fifth connection passage 310, through a small hole to expand the refrigerant to thereby change the refrigerant into atomized low-temperature and low-pressure refrigerant. The expansion valve 150 includes a valve body 152 and a temperature sensing member 154. The valve body 152 is provided at a position upstream of the evaporator 80. The temperature sensing member 154 is provided at a position downstream of the evaporator 80.

[0041] At the expansion valve 150, the flow rate of refrigerant in the valve body

152 is determined on the basis of the temperature of refrigerant at the temperature sensing member 154. The flow rate of refrigerant is determined so that all the atomized refrigerant is completely vaporized in the evaporator 80.

[0042] At the expansion valve 150, for example, the valve element of the valve body 152 is moved by changing the pressure of gas based on the temperature of refrigerant at the temperature sensing member 154 to determine the flow rate of refrigerant. In the temperature sensing member 154, gas is encapsulated inside a casing. Note that the correlation between the temperature of refrigerant and the displacement of the valve element is adjusted in advance on the basis of the size of the casing, the amount of gas, or the like.

[0043] The evaporator 80 absorbs heat of air in the cabin of the vehicle, introduced so as to be in contact with the evaporator 80, in such a manner that atomized refrigerant is vaporized. Air of which the temperature is decreased by absorption of heat is returned into the cabin of the vehicle to cool the cabin of the vehicle.

[0044] The evaporator 80 includes tubes and fins. The tubes flow refrigerant. The fins are used to exchange heat between refrigerant flowing through the tubes and air around the evaporator 80. Atomized refrigerant flows through the tubes. Refrigerant flowing through the tubes is evaporated to absorb heat of air in the cabin of the vehicle via the fins. Vaporized refrigerant flows to the compressor 20 via the third connection passage 306. The structure of the evaporator 80 is basically similar to that of the first condenser 40 or second condenser 42 except size and shape, so the detailed description thereof is not repeated.

[0045] The cooling portion 120 includes an inverter 122, a motor generator 124 and a cooling passage 126. Both ends of the cooling passage 126 are respectively connected to the other end of the first connection passage 302 and one end of the second connection passage 304.

[0046] The cooling portion 120 is provided so as to be able to exchange heat between refrigerant and the inverter 122 and motor generator 124. In the present embodiment, the cooling portion 120, for example, is configured to be able to exchange heat between the electrical devices and refrigerant using the cooling passage 126 formed so that refrigerant is in contact with the casings of the electrical devices; instead, the cooling portion 120 may be configured to be able to bring a heat exchanger into contact with refrigerant when the electrical devices are connected to the heat exchanger via a heat transfer device, such as a heat pipe.

[0047] In the present embodiment, the cooling portion 120 may form the cooling passage 126 so that the motor generator 124 is cooled after the inverter 122 is cooled or may form the cooling passage 126 so that the inverter 122 is cooled after the motor generator 124 is cooled or may form the cooling passage 126 so that the inverter 122 and the motor generator 124 are cooled in parallel with each other. The cooling portion 120 is desirably provided so that the electrical device having a lower upper limit of the target temperature range between the electrical devices to be cooled is cooled and then the electrical device having a higher upper limit of the target temperature range between the electrical devices to be cooled is cooled.

[0048] The cooling passage 126 has a portion next to the casing of the inverter 122 and a portion next to the motor generator 124. Heat may be exchanged at those portions between refrigerant flowing through the cooling passage 126 and the inverter 122 and motor generator 124.

[0049] When cooling is performed, the ECU 400 generates the control signal CI and transmits the generated control signal CI to the compressor 20 in order to operate the compressor 20.

[0050] The operation of the thus configured cooling system 10 according to the present embodiment will be described. For example, cooling is performed when the switch for cooling is turned on or the automatic control mode in which the temperature of the cabin of the vehicle is automatically adjusted to a set temperature is selected and when the temperature in the vehicle cabin is higher than the set temperature. At this time, the ECU 400 transmits the control signal CI so that the compressor 20 operates. The compressor 20 operates on the basis of the control signal C 1 from the ECU 400.

[0051] Refrigerant discharged from the compressor 20 through the operation of the compressor 20 is introduced into the first condenser 40 via the fourth connection passage 308. Refrigerant introduced in the first condenser 40 exchanges heat with outside air via the fins 62 when flowing through the plurality of tubes 60 in a distributed manner to be condensed and part or whole of refrigerant is liquefied. Note that, when part or whole of refrigerant condensed from refrigerant in the first condenser 40 is liquefied, the temperature of refrigerant is kept at a constant temperature. Refrigerant condensed in the first condenser 40 is supplied to the cooling portion 120 via the first connection passage 302.

[0052] Refrigerant supplied to the cooling portion 120 cools the inverter 122 and the motor generator 124 and then flows to the second condenser 42 via the second connection passage 304. Liquefied refrigerant within refrigerant introduced in the second condenser 42 exchanges heat with outside air via the fins 68 when flowing through the plurality of tubes 66 in a distributed manner to be decreased in temperature. That is, refrigerant has a larger degree of supercooling than that when refrigerant is saturated liquid.

[0053] Refrigerant cooled in the second condenser 42 flows to the expansion valve 150 via the fifth connection passage 310. Liquid refrigerant is changed into atomized refrigerant by the expansion valve 150, and the atomized refrigerant is supplied to the evaporator 80. Atomized refrigerant absorbs heat of air in the cabin of the vehicle through evaporation in the evaporator 80. Gaseous refrigerant vaporized through evaporation flows to the compressor 20 via the third connection passage 306. Gaseous refrigerant compressed by the compressor 20 flows to the first condenser 40, and heat of the compressed gaseous refrigerant is dissipated in the first condenser 40 to be condensed again. In this way, refrigerant flows from the compressor 20 in order of the first condenser 40, the cooling portion 120, the second condenser 42 and the evaporator 80 and then returns to the compressor 20.

[0054] FIG. 3 shows an example of a variation in the temperature of refrigerant flowing through the inside of the second condenser 42. In FIG. 3, the ordinate axis represents a refrigerant temperature. The abscissa axis represents a flow distance from the inlet portion 48 of the second condenser 42 to the outlet portion 50 of the second condenser 42.

[0055] It is assumed that, for example, the temperature of refrigerant flowing to the inlet portion 48 of the second condenser 42 via the cooling portion 120 is 60°C and the outside air temperature is 30°C.

[0056] As indicated by the solid line in FIG. 3, the temperature of refrigerant flowing to the inlet portion 48 of the second condenser 42 decreases as the refrigerant approaches the outlet portion 50 because of heat dissipation via the plurality of tubes 66 and the plurality of fins 68, and decreases to 30°C that is equal to the outside air temperature at the outlet portion 50.

[0057] On the other hand, if refrigerant flowing through the first condenser 40 flows to the second condenser 42 without passing through the cooling portion 120, heat is not absorbed from the electrical devices in the cooling portion 120, so refrigerant having a lower temperature (for example, 50°C) than 60°C flows to the second condenser 42.

[0058] As indicated by the broken line in FIG. 3, the temperature of refrigerant flowing to the inlet portion 48 of the second condenser 42 decreases as the refrigerant approaches the outlet portion 50 because of heat dissipation via the plurality of tubes 66 and the plurality of fins 68, and decreases to 30°C that is equal to the outside air temperature before the outlet portion 50.

[0059] The amount of heat dissipation in the second condenser 42 may be calculated by multiplying the difference between the temperature of refrigerant and the outside air temperature by a coefficient. That is, the amount of heat dissipation in the second condenser 42 when refrigerant passes through the cooling portion 120 is larger by an amount corresponding to the diagonally shaded area in FIG. 3 than the amount of heat dissipation in the second condenser 42 when refrigerant does not pass through the cooling portion 120.

[0060] In this way, with the cooling system according to the present embodiment, the cooling portion for cooling the electrical device is provided in the path of refrigerant flowing from the first condenser 40 to the second condenser 42 to thereby make it possible to cool the electrical devices using refrigerant flowing from the first condenser 40. Therefore, it is not necessary to decompress refrigerant into perfect gas at the cooling portion 120 unlike the case of the evaporator 80, so it is not necessary to increase the power of the compressor as compared with when refrigerant supplied to the cooling portion is decompressed into perfect gas. As a result, it is possible to avoid increasing the size of the compressor or providing an exclusive pump for cooling the electrical devices. Thus, it is possible to provide the cooling system that cools the electrical devices without deteriorating power required of the compressor and mountability of the cooling system to the vehicle. [0061] In addition, refrigerant in the first condenser 40 is in a state where a saturated liquid state and a saturated vapor state are mixed. The temperature of refrigerant at this time is kept at a constant temperature, so the difference from the outside air temperature is also kept in a constant state. As a result, in the first condenser 40, a constant amount of heat dissipation may be kept.

[0062] In contrast to this, refrigerant in the second condenser 42 decreases in temperature because of supercooling. At this time, the difference between the temperature of refrigerant and the outside air temperature reduces, so the amount of heat dissipation of the second condenser 42 decreases as compared with when the temperature of refrigerant is kept at a constant temperature.

[0063] Therefore, by flowing refrigerant through the cooling portion 120 to increase the temperature of refrigerant, the amount of heat dissipation in the second condenser 42 may be increased as compared with when refrigerant is not flowed through the cooling portion. That is, heat received from the cooling portion 120 may be dissipated without increasing the size of the second condenser 42.

[0064] In the present embodiment, the "electrical devices" equipped for the vehicle to be cooled using the cooling system 10 are the inverter 122 and the motor generator 124 by way of example; however, the "electrical device" is not specifically limited. The "electrical device" may be the one that is at least operated to generate heat. For example, the "electrical device" may be at least any one of the inverter, the motor generator 124, the battery that serves as an electrical storage device, a converter for stepping up the voltage of the battery and a DC/DC converter for stepping down the voltage of the battery.

[0065] In the present embodiment, the first condenser 40 and the second condenser 42 are integrally arranged; however, the aspect of the invention is not specifically limited to integral arrangement. For example, as shown in FIG. 4, the first condenser 40 and the second condenser 42 may be arranged separately.

[0066] In the present embodiment, when cooling is performed, the electrical devices are cooled by the cooling portion 120 by way of example; instead, for example, the ECU 400 may be configured to operate the compressor 20 when the temperature of any one of the electrical devices or the temperature of refrigerant flowing through the cooling portion 120 is higher than a predetermined temperature.

[0067] In the present embodiment, the first condenser 40 and the second condenser 42 each have a structure such that the plurality of tubes are arranged in parallel with one another; however, the structure of each of the first condenser 40 and the second condenser 42 is not specifically limited to such a structure. For example, as shown in FIG. 5, the first condenser 40 may have a structure such that a continuous path through which refrigerant flows is formed of a single tube 70 that extends from the inlet portion 44 to the outlet portion 46. In addition, the second condenser may have a structure such that a continuous path through which refrigerant flows is formed of a single tube 72 that extends from the inlet portion 48 to the outlet portion 50.

[0068] Furthermore, the specifications of the first condenser 40 may be determined so as to be able to completely liquefy vaporized refrigerant, flowing from the compressor 20, inside the first condenser 40.

[0069] Furthermore, in the present embodiment, the first condenser 40 condenses vaporized refrigerant, flowing from the compressor 20, into a liquefied state or a state where vaporized refrigerant and liquefied refrigerant are mixed inside the first condenser 40 and then liquefied refrigerant is supercooled in the second condenser 42; however, the aspect of the invention is not specifically limited to this configuration. For example, it is applicable that the first condenser 40 condenses refrigerant so that the temperature of refrigerant is lower than or equal to a temperature required to cool the electrical devices and the second condenser 42 condenses refrigerant from the cooling portion 120 into a liquefied state or a state where vaporized refrigerant and liquefied refrigerant are mixed.

[0070] Furthermore, the expansion valve 150 may include an electromagnetic valve and a sensor that detects the temperature of refrigerant. In this case, the ECU 400 may be configured to adjust the flow rate of refrigerant in the electromagnetic valve on the basis of the temperature of refrigerant, detected by the sensor. [0071] The embodiment described above should be regarded as only illustrative in every respect and not restrictive. The scope of the invention is indicated not by the above description but by the appended claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the appended claims.

Claims

CLAIMS:

1. A cooling system that cools an electrical device equipped for a vehicle, characterized by comprising:

a compressor that circulates refrigerant;

a first condenser that condenses the refrigerant;

a second condenser that is provided downstream of the first condenser;

an evaporator that uses the refrigerant from the second condenser to cool a cabin of the vehicle; and

a cooling portion that is provided in a path of the refrigerant flowing from the first condenser toward the second condenser and that uses the refrigerant from the first condenser to cool the electrical device.

2. The cooling system according to claim 1, wherein

the cooling system has a first passage that introduces the refrigerant from the first condenser to the cooling portion and a second passage that introduces the refrigerant from the cooling portion to the second condenser, and

the path of the refrigerant flowing from the first condenser toward the second condenser passes through the first passage, the cooling portion and the second passage.

3. The cooling system according to claim 1 or 2, wherein the first condenser and the second condenser are integrally arranged.

4. The cooling system according to claim 1 or 2, wherein the first condenser and the second condenser are separately arranged.

5. The cooling system according to any one of claims 1 to 4, wherein

the first condenser condenses the refrigerant from the compressor into any one of a first state where the refrigerant is liquefied and a second state where the vaporized refrigerant and the liquefied refrigerant are mixed, and

the second condenser decreases a temperature of the liquefied refrigerant.

6. The cooling system according to any one of claims 1 to 4, wherein

the first condenser condenses the refrigerant into a state where a temperature of the refrigerant is lower than or equal to a temperature required to cool the electrical device, and

the second condenser condenses the refrigerant from the cooling portion into any one of a first state where the refrigerant is liquefied and a second state where the vaporized refrigerant and the liquefied refrigerant are mixed.

7. The cooling system according to any one of claims 1 to 6, further comprising:

a valve that is provided between the second condenser and the evaporator, and that supplies the atomized refrigerant to the evaporator when the cabin of the vehicle is cooled.

8. The cooling system according to any one of claims 1 to 7, wherein the vehicle uses an electrical rotating machine as a driving source.

9. The cooling system according to claim 8, wherein the vehicle that uses the electrical rotating machine as a driving source is any one of an electric vehicle, a fuel cell vehicle and a hybrid vehicle.