Cooling device

Abstract

A cooling device for an electric vehicle that uses a refrigeration cycle system and a water cooling system together to provide the cooling device capable of cooling a motor, a power converter, or a storage battery with good responsiveness, the cooling device 12 comprising: a water cooling system 35 that cools a cooled body by circulating the cooling water; and a refrigeration cycle system 36 that cools the cooling water to an outside air temperature or below by applying a gas-liquid phase change of a refrigerant.The water cooling system 35 includes: a first flow channel 31a for allowing the cooling water flowing through a radiator 5 that radiates heat of the cooling water to the outside air to flow through the cooled body; a second flow channel 31b for allowing the cooling water cooled to the outside air temperature or lower by an evaporator 6 of the refrigeration cycle system 36 to flow through the cooled body, provided at the first flow channel 31a; and flow rate control units 9a, 9b for controlling the flow rates of the cooling water flowing in the first flow channel 31a and the second flow channel 31b.

Description

Technical field

[0001] The present invention relates to a cooling device and relates, for example, to a cooling device for an electric vehicle which uses a water cooling system and a refrigeration cycle system together. State of the art

[0002] In an electric vehicle, such as an electric car or a hybrid vehicle, a power converter (inverter) converts direct current supplied by a high-voltage storage battery (e.g., a lithium-ion battery) into alternating current, and a motor (e.g., a three-phase motor) rotates using this alternating current, thereby generating the vehicle's driving force. Further, when the vehicle's speed decreases, regenerative energy obtained by regenerative power generation of the motor is stored in the storage battery, thereby reducing energy waste and realizing effective energy utilization.

[0003] Incidentally, it is known that there is a possibility that the power converter used in the above-described electric vehicle such as the electric car or the hybrid vehicle is thermally destroyed by heat generation caused by a switching operation of a switching element therein.

[0004] Furthermore, it is also known that the output characteristics of the motor, the charge / discharge behavior or the life characteristics of the storage battery or the like have high temperature dependencies and that it is necessary to keep them within a suitable temperature range in order to operate the storage battery or the motor effectively.

[0005] To address these problems, Patent Literature 1 discloses a conventional motor driving device designed to achieve both thermal protection of a power converter and power saving.

[0006] The motor driving device disclosed in Patent Literature 1 is a device in which, in a water cooling system that flows cooling water through a motor, a power converter, or the like and cools the motor, the power converter, or the like, a target flow rate of the cooling water flowing through a refrigerant flow channel is set based on a current command value of the motor, a water pump is driven in such a manner that the cooling water circulates at the set target flow rate, and the power converter is cooled with good responsiveness.

[0007] Further, Patent Literature 2 discloses a conventional set temperature holding device of a storage battery for an electric car, which is designed to keep the temperature of the storage battery at a set temperature.

[0008] The set temperature holding device disclosed in Patent Literature 2 is a device that uses a refrigeration cycle system for indoor cooling and a water cooling system for cooling the storage battery together, and cools the storage battery by providing an intermediate heat exchanger between the refrigeration cycle system and the water cooling system and performing heat exchange therebetween. List of referencesPatent literature Patent Literature 1: JP 2007-166804 A Patent Literature 2: JP 2006-296193 A Patent literature 3: DE 10 2004 055 695 A1 Patent Literature 4: US 4,015,962 A Patent literature 5: DE 60 2004 007 309 T2 Patent Literature 6: US 5,862,675 A Patent Literature 7: WO 2011 / 096 102 A1 Patent literature 8: DE 10 2006 004 419 A1 Patent literature 9: US 2005 / 061 497 A1 Patent Literature 10: CN 101 574 923 A Summary of the inventionTechnical problem

[0009] According to the motor drive device disclosed in Patent Literature 1, a cooling medium with good responsiveness can be supplied to the power converter where a temperature rise is expected, the power converter can be reliably protected from overheating, and an appropriate flow rate of the cooling medium can be supplied against the temperature rise of the power converter that fluctuates in response to the motor output. Furthermore, compared to, for example, a motor drive device in which a supply rate of the cooling medium must be set to the maximum value due to insufficient responsiveness, the power consumption of the cooling device of the motor drive device can be kept low.

[0010] According to the temperature control device disclosed in Patent Literature 2, the intermediate heat exchanger is further provided between the refrigeration cycle system and the water cooling system, and the water cooling system that flows the cooling water through the storage battery is controlled by a temperature control unit. Accordingly, the storage battery can be effectively cooled.

[0011] However, in the engine drive device disclosed in Patent Literature 1, in a case where a radiator constituting the water cooling system is mounted near a bumper on the front of a vehicle, the radiator and the engine or the like are arranged separately, and the piping length for circulating the cooling water in the water cooling system becomes longer. Therefore, even if the driving of the cooling water pump is controlled and the flow rate of the cooling water is increased, the time for the cooling water cooled by the radiator to reach the engine or the power converter becomes longer, and there is a possibility that the temperature of the cooling water will rise and the cooling performance of the engine or the power converter will decrease. Furthermore, since the volume of the cooling water, that is, the heat capacity of the cooling water in the piping increases, there is also a problem in that it is difficult to effectively cool all the cooling water to a predetermined temperature.Furthermore, since the propagation of vibrations caused by the motor's drive torque is blocked by the inverter or a body structure, it is necessary to connect the motor and the inverter with a pipe formed of an elastic body such as a plastic hose, and there is a possibility that the cooling performance of the motor or power converter will be further reduced. With this configuration, in a case where a rapid temperature rise in the motor, power converter, or the like is expected to correspond to, for example, a driver's rapid acceleration or a driving condition such as a rapid change in driving load, there is a problem in that the motor, power converter, or the like cannot be cooled with good responsiveness.

[0012] Furthermore, in the set temperature holding device disclosed in Patent Literature 2, the piping length of the cooling water constituting the cooling system becomes relatively long in the same way as the motor driving device disclosed in Patent Literature 1. As a result, even if the temperature of the cooling water is lowered by means of the refrigeration cycle system, there is a problem that the heat capacity of the cooling water is increased and excellent cooling responsiveness cannot be obtained.

[0013] DE 10 2004 055 695 A1 (cf. patent literature 3) describes a vapor compression cooling device for collecting heat energy from an internal combustion engine, wherein the internal combustion engine is operated as a heat source.

[0014] US 4 015 962 A (see patent literature 4) describes a cooling device with two separately controlled fluid circuits connected by a heat exchanger. One fluid circuit serves for heating and the other fluid circuit for cooling.

[0015] DE 60 2004 007 309 T2 (cf. patent literature 5) describes an air conditioning device for a vehicle with a single cooling circuit.

[0016] US 5 862 675 A (cf. Patent Literature 6) describes a cooling device for a vehicle with a bypass line for recirculating heated coolant in the cooling device when no cooling power is required.

[0017] WO 2011 / 096 102 A1 (cf. patent literature 7) describes a cooling system with two circuits, wherein the second circuit is connected to the first circuit and a compressor of the second circuit presses coolant into the first circuit.

[0018] DE 10 2006 004 419 A1 (cf. Patent Literature 8) describes a cooling structure comprising a plurality of heat-generating elements, each having a plate shape. The heat-generating elements are arranged in a plate thickness direction such that they have specific spaces for forming fluid channels, each of which is provided between adjacent heat-generating elements.

[0019] US 2005 / 061 497 A1 (cf. patent literature 9) describes a temperature control device with two cooling circuits arranged in parallel.

[0020] CN 101 574 923 A (see Patent Literature 10) describes a thermal management system for vehicle batteries with two cooling circuits and one heating mode. The first cooling mode uses a battery cooler with a fan when the air conditioning system is off. The second cooling mode cools via a refrigerant-to-coolant heat exchanger when the air conditioning system is running.

[0021] A heating mode warms the battery in cold ambient conditions, with a 3-way valve controlling the circulation of the coolant.

[0022] In view of the problems described above, an object of the invention is to provide a cooling device capable of ensuring excellent responsiveness to cooling in the cooling device using a refrigeration cycle system and a water cooling system together. Solution to the problem

[0023] The problem is solved by the features of claim 1. Particular embodiments are described in the dependent claims.Advantageous effects of the invention

[0024] According to the cooling device of the present invention, by configuring the first cooling system for cooling the cooled body from the first flow channel that cools the cooling medium by means of the radiator and the second flow channel that cools the cooling medium by means of the second cooling system, the flow rate of the cooling medium in the second flow channel, particularly the heat capacity of the cooling medium at the time of cooling amplification, can be reduced. Accordingly, the cooling medium flowing through the cooled body can be effectively cooled, and the cooled body can be cooled with good responsiveness.

[0025] Problems, structures and effects not previously described will become clear from the following description of embodiments. Short description of the drawings Fig. 1 is an internal structural view illustrating a basic structure of a front interior of a vehicle to which Embodiment 1 of a cooling apparatus according to the present invention is related. Fig. 2 is a diagram illustrating in a time series an example of a temperature change of a power converter in a case where the temperature of the power converter or the like is measured by means of the Fig. 1 illustrated cooling device. Fig. 3 is a diagram illustrating in a time series another example of a temperature change of the power converter in a case where the temperature of the power converter or the like is measured by means of the Fig. 1 illustrated cooling device. Fig. 4 is an internal structural view showing a basic structure of a front interior of a vehicle to which Embodiment 2 of a cooling device according to the present invention is related. Description of embodiments

[0026] Hereinafter, embodiments of cooling devices according to the present invention will be described with reference to the drawings. [Embodiment 1]

[0027] Fig. 1 illustrates a basic structure of a front interior of a vehicle to which Embodiment 1 of a cooling device according to the present invention applies. Here, in the illustrated example, a cooling device 12 of Embodiment 1 is applied to an electric vehicle having a front-wheel drive system. The right side in the drawing is the traveling direction of a vehicle 41, and an electric drive system 40 including a power converter 10, a motor 11, or the like is mounted near a front wheel of the vehicle 41. Note that the cooling device 12 of Embodiment 1 may also apply to an electric vehicle having a rear-wheel drive system or a four-wheel drive system, a hybrid electric vehicle equipped with a motor, or the like.

[0028] The illustrated electric drive system 40 of the electric vehicle 41 includes a storage battery 14 that stores the drive energy, the power converter 10 that controls the drive power supplied to the motor 11 by means of the power supplied from the storage battery 14, the motor 11 that generates the torque (driving force) of a wheel by means of a drive power supplied from the power converter 10, and the cooling device 12 that cools the power converter 10, the motor 11, or the storage battery 14.

[0029] Furthermore, the cooling device 12 described above comprises a refrigeration cycle system (second cooling system) 36 and a water cooling system (first cooling system) 35.

[0030] The refrigeration cycle system 36 described above includes a compressor 1, a condenser 4, a pressure reducer (expansion valve) 3, an evaporator 6, and a refrigerant piping 18. A fan 13 is attached to the condenser 4 and is capable of controlling a flow rate of cooling air based on a command signal from a controller 15. Here, a refrigerant suitable for the refrigeration cycle, such as alternative Freon, circulates in the refrigerant piping 18 connecting the compressor 1, the condenser 4, the pressure reducer 3, and the evaporator 6. This refrigerant circulates in the refrigerant piping 18 and is cooled by the refrigeration cycle, with the compressor 1 serving as an energy source.

[0031] Further, the above-described water cooling system 35 includes a radiator 5, a tank 8, a pump 7, flow rate control valves (flow rate control unit) 9a, 9b, the evaporator 6 (shared with the refrigeration cycle system 36), and a flow channel 31 for cooling water. The fan 13, shared with the above-described compressor 4, is attached to the radiator 5 and capable of controlling the flow rate of the cooling air based on the command signal from the controller 15. Here, cooling water, such as antifreeze, circulates in the flow channel 31 of the water cooling system 35, which connects the radiator 5, the tank 8, the pump 7, the flow rate control valves 9a, 9b, the evaporator 6, the power converter 10, the motor 11, and the storage battery 14.

[0032] It should be noted that the illustrated controller 15 drives and controls the compressor 1, the fan 13, the pump 7, the flow rate control valves 9a, 9b and the like in accordance with the conditions of the power converter 10, the motor 11 or the storage battery 14 and the cooling water or the refrigerant detected by means of a temperature sensor, a pressure sensor or the like (not illustrated), and is capable of controlling the temperatures of the refrigerant of the refrigeration cycle system 36 and the cooling water of the water cooling system 35.

[0033] Here, the cooling water flow channel 31 of the previously described water cooling system 35 includes a first flow channel 31a connecting the radiator 5, the tank 8, the pump 7, the power converter 10, the motor 11, and the storage battery 14, and a second flow channel 31b connecting the evaporator 6, the pump 7, the power converter 10, the motor 11, and the storage battery 14. In other words, the first flow channel 31a and the second flow channel 31b share a portion 31c connecting the pump 7, the power converter 10, the motor 11, and the storage battery 14. The second flow channel 31b is formed by branching off a flow channel of the first flow channel 31a passing through the pump 7, the power converter 10, the motor 11, and the storage battery 14, and rejoining the branched flow channel with the first flow channel 31a upstream of the pump 7.The cooling water of each of the first flow channel 31a and the second flow channel 31b is supplied under pressure by the pump 7 provided at the above-described common portion 31c as a power source. Note that the tank 8 provided at the first flow channel 31a absorbs the volume change due to thermal expansion, leakage, or the like of the cooling water flowing in the first flow channel 31a. Furthermore, the respective first flow channel 31a and the second flow channel 31b may be separate flow channels without a common portion 31c.

[0034] Furthermore, the first flow channel 31a and the second flow channel 31b respectively include the above-described flow rate control valves 9a, 9b and temperature sensors 16a, 16b that detect the temperature of the cooling water. With this configuration, the rotational speed of the pump 7 or the opening degree of the flow rate control valves 9a, 9b can be changed separately according to the driving state of the power converter 10, the motor 11, or the storage battery 14, or the measured values ​​of the temperature sensors 16a, 16b and the flow rates of the cooling water flowing in the first flow channel 31a and the second flow channel 31b can be controlled accordingly.

[0035] In this way, the radiator 5 and the evaporator 6 of the refrigeration cycle system 36 are connected in parallel to the power converter 10, the engine 11, and the storage battery 14 to be cooled, the first flow passage and the second flow passage share the pump 7, and the flow rate ratios of the cooling water flowing in the first flow passage and the second flow passage are controlled by the flow rate control valves 9a and 9b, respectively. Accordingly, an increase in the basic number of the pumps 7 can be suppressed, and the structure of the cooling device 12 can be simplified.

[0036] Furthermore, by respectively providing the temperature sensors 16a, 16b at the first flow passage 31a and the second flow passage 31b, even in a case where the water temperatures of the cooling water flowing in the respective flow passages are different, the flow rates of the cooling water in the first flow passage 31a and the second flow passage 31b can be controlled based on these water temperatures. Note that the water temperature of the common portion 31c of the first flow passage 31a and the second flow passage 31b can be judged based on the above-described two temperature sensors 16a, 16b and the opening degrees of the flow rate control valves 9a, 9b.For example, in a case where the flow rate control valve 9a is opened and the flow rate control valve 9b is closed, it can be estimated that the water temperature of the cooling water flowing in the common portion 31c is substantially the same as the measured value of the temperature sensor 16a provided at the first flow channel 31a. Further, in a case where the flow rate control valve 9a is closed and the flow rate control valve 9b is opened, it can be estimated that the water temperature of the cooling water flowing in the common portion 31c is substantially the same as the measured value of the temperature sensor 16b provided at the second flow channel 31b. By performing such temperature estimation, the increase in the basic number of temperature sensors can be suppressed, and the structure of the cooling device 12 can be simplified.When the temperature sensor is provided at the common portion 31c of the flow passage 31, it is noted that the temperature control inside the power converter 10 or inside the motor 11 can be performed with higher precision.

[0037] Here, the cooling water circulating in the first flow passage 31a is cooled by air flowing through the radiator 5 connected to the first flow passage 31a. While the cooling water flowing in the first flow passage 31a cannot be cooled to the outside air temperature or lower because the power consumption of the pump 7 or the fan 13 is lower than the power consumption of the compressor 1, according to such cooling by the radiator 5, the cooling water can be cooled with a small amount of power consumption.

[0038] Furthermore, the cooling water circulating in the second flow channel 31b is cooled by the refrigerant flowing through the evaporator 6 of the refrigeration cycle system 36. The refrigerant circulating in the refrigerant piping 18 connected to the evaporator 6 of the refrigeration cycle system 36 is supplied under pressure to the condenser 4 by the compressor 1 and is cooled by this condenser 4. While the power consumption of such cooling by the refrigeration cycle system 36 is comparatively larger than that of cooling by the chiller 5, the cooling water can be cooled to the outside air temperature or below.Therefore, even in a case where a load of the power converter 10, the motor 11, or the storage battery 14 is high, they can be cooled by means of the cooling water having a temperature lower than the cooling water of the first flow channel 31a, and the temperature rise of the power converter 10, the motor 11, or the storage battery 14 can be effectively suppressed.

[0039] Note that a part of the second flow passage 31b other than the common portion 31c with the first flow passage 31a is covered with a member 33 having high insulation performance, such as a foam material. With this configuration, heat input from the outside air into the cooling water cooled to the outside air temperature or lower can be suppressed, and the power consumption of the compressor 1 can be effectively suppressed.

[0040] With such a configuration, in the above-described cooling device 12, temperatures of the refrigerant of the refrigeration cycle system 36 and the cooling water of the water cooling system 35 can be changed by controlling the operating states of the compressor 1 of the refrigeration cycle system 36, the pump 7 and the flow rate control valves 9a, 9b of the water cooling system 35 and the fan 13.

[0041] For example, in a case where the load of the power converter 10, the motor 11, or the storage battery 14 is low and their heat generation amounts are relatively small, the cooling water is circulated only in the first flow channel 31a by controlling the flow rate control valves 9a, 9b, and the heat of the cooling water is radiated from the radiator 5, thereby cooling the cooling water. With this configuration, the cooling water of the water cooling system 35 can be cooled with little energy.

[0042] In contrast, for example, in a case where the load of the power converter 10, the motor 11, or the storage battery 14 is high, the heat generation amounts thereof are high, and the cooling water needs to be cooled to a temperature lower than the outside air temperature, the cooling water is circulated only in the second flow passage 31b by controlling the flow rate control valves 9a, 9b, and the heat of the cooling water is radiated through the evaporator 6 of the refrigeration cycle system 36, thereby cooling the cooling water. With this configuration, even in the case where the load of the power converter 10, the motor 11, or the storage battery 14 is high, the cooling water flowing therethrough is reliably cooled, and the temperature rise of the power converter 10, the motor 11, or the storage battery 14 can be suppressed.

[0043] As illustrated, note that the power converter 10 is supported by the motor 11. Further, the power converter 10 and the motor 11 are connected to the tires via a speed reducer (not illustrated). Here, the power converter 10 and the motor 11 are supported by a body through an elastic body such as rubber, so that vibration due to the drive torque is not transmitted to the body. On the other hand, the radiator 5 and the condenser 4 are provided near the bumper on the front of the body. Therefore, the power converter 10 or the motor 11 and the radiator 5 are connected by a rubber hose 32 to absorb the relative displacement between the power converter 10 or the motor 11 and the radiator 5 generated by the vibration of the power converter 10 or the motor 11.

[0044] In this way, in the first flow channel 31a of the water cooling system 35, it is necessary to have a certain distance between the power converter 10 or the engine 11 and the radiator 5, and it is necessary to flow the cooling water through the interior of the radiator 5 and also the tank 8. Further, since a part of the first flow channel 31a must be constructed of the rubber hose 32, the flow rate of the cooling water flowing in the first flow channel 31a is comparatively increased, and it is difficult to cool the cooling water with good responsiveness.

[0045] On the other hand, with respect to the second flow passage 31b of the water cooling system 35, since it is not necessary to provide the flow passage on the front of the vehicle as the first flow passage 31a, the power converter 10, the motor 11 or the storage battery 14, and the evaporator 6 can be formed by connecting via relatively short flow passages. Further, since the evaporator 6 can be assisted by the power converter 10, it is not necessary to connect the evaporator 6 and the power converter 10 or the motor 11 with a rubber hose or the like. Moreover, if the tank 8 and the radiator 5 are provided at the first flow passage 31a, the flow rate of the cooling water in the second flow passage 31b to be cooled by the refrigeration cycle system 36 can be kept low.

[0046] With this configuration, even in a case where the control of cooling the cooling water flowing in the second flow channel 31b to the predetermined temperature is performed to cool the power converter 10, the motor 11, or the storage battery 14, the heat capacity of the cooling water can be small and the water temperature can be lowered in a relatively short time. Accordingly, the cooling water flowing in the second flow channel 31b can be effectively cooled.

[0047] Note that the evaporator 6 has a structure supported by the power converter 10 in Embodiment 1, but the evaporator 6 may be supported by the engine 11 or the storage battery 14. Furthermore, although the rubber hose or the like is required for the flow passage, for example, even if the evaporator 6 is supported by the vehicle 41, the heat capacity with respect to the cooling water of the tank 8 and the radiator 5 can be reduced.

[0048] Next, the cooling method of the cooling water in the water cooling system 35 by the cooling device 12 of the present embodiment 1 will be described.

[0049] First, a cooling method of the cooling water flowing in the first flow channel 31a will be described.

[0050] In a case where the load of the power converter 10, the motor 11 or the storage battery 14 is low and their heat generation amounts are relatively small, the Fig. As illustrated in FIG. 1, the controller 15 closes the flow rate control valve 9a of the first flow channel 31a, closes the flow rate control valve 9b of the second flow channel 31b, and circulates the cooling water only in the first flow channel 31a. The cooling water circulating in the first flow channel 31a absorbs the heat of the power converter 10, the motor 11, and the storage battery 14 during circulation, and their water temperature is increased. The cooling water, whose temperature has been increased in this way, flows into the radiator 5 through the flow rate control valve 9a. Here, the outside air, whose temperature is lower than that of the cooling water, is passed through the radiator 5, and the heat of the cooling water is radiated to the outside air.

[0051] The controller 15 controls the rotational speeds of the pump 7 and the fan 13 in response to the temperatures of the cooling water and the outside air, the heat generation amount of the power converter 10, the motor 11 or the storage battery 14 and the traveling speed or the like of the vehicle 41. Here, the rotational speeds of the pump 7 and the fan 13 are controlled so as to achieve the minimum power consumption with which the required cooling capacity can be obtained.

[0052] For example, when the temperature of the cooling water is lower than the predetermined temperature, the rotations of the pump 7 and the fan 13 are stopped, or the pump 7 and the fan 13 are driven at the minimum rotation speeds. Further, when the traveling speed of the vehicle 41 is fast, since the air flow rate of the radiator 5 can be secured by the wind, the driving of the fan 13 is stopped. Furthermore, when the temperature of the cooling water exceeds or is predicted to exceed the predetermined temperature, the rotation speeds of the pump 7 and the fan 13 are increased, and the cooling capacity is increased. Note that according to such a cooling method, although the cooling capacity is limited as described above, there is no need to drive the compressor 1 for the cooling water flowing in the first flow passage 31a.Accordingly, the cooling water flowing in the first flow channel 31a can be cooled with the small amount of power consumption.

[0053] Next, the cooling method of the cooling water flowing in the second flow channel 31b will be described.

[0054] In a case where the load of the power converter 10, the motor 11 or the storage battery 14 is high and their heat generation amounts are relatively large, the Fig. 1, the controller 15 closes the flow rate control valve 9b of the second flow channel 31b, closes the flow rate control valve 9a of the first flow channel 31a, and circulates the cooling water only in the second flow channel 31b. Here, the cooling water in the second flow channel 31b is supplied under pressure by the pump 7, and the controller 15 is able to adjust the flow rate of the cooling water flowing in the second flow channel 31b by controlling the rotational speed of the pump 7. The cooling water flowing in the second flow channel 31b absorbs the heat of the power converter 10, the motor 11, and the storage battery 14 during circulation, and its water temperature is increased. The cooling water, whose temperature has been increased in this way, flows into the evaporator 6 through the flow rate control valve 9b.Then, the heat of the cooling water is exchanged with the refrigerant of the refrigeration cycle system 36 at the evaporator 6, and the water temperature is lowered.

[0055] Here, the refrigerant in the refrigerant piping 18 of the refrigeration cycle system 36 is circulated through the compressor 1 in the direction of arrow A18. The refrigerant is compressed to become a high-temperature and high-pressure gas in the compressor 1, and then condensed into a high-pressure liquid in the condenser 4 by dissipating heat into the air. After the cooling water flows through the refrigerant piping 18, its pressure is reduced by the pressure reducer 3, so that the pressure and temperature of the refrigerant become low (refrigerant existing in two layers of liquid and gas). After that, the heat of the refrigerant is exchanged with the cooling water flowing in the second flow channel 31b through the evaporator 6.Therefore, by controlling the driving state of the compressor 1, the controller 15 is able to adjust the temperature and flow rate of the refrigerant and adjust the water temperature of the cooling water flowing in the second flow channel 31b.

[0056] In this way, in response to the power output of the power converter 10, the motor 11, or the storage battery 14 serving as a heat-generating body, the flow rate control valves 9a, 9b provided in the first flow channel 31a and the second flow channel 31b are controlled, and the flow rates of the cooling water in the first flow channel 31a and the second flow channel 31b are controlled. Accordingly, even in a case where a high cooling capacity is required, the cooling water can be cooled with good responsiveness, and the heat-generating bodies can be cooled.

[0057] Next, with reference to Fig. 2 and Fig. 3 a method for controlling a temperature of the power converter 10 by means of the Fig. 1 will be described in more detail. Note that this control method involves switching the flow channel of the cooling water from the first flow channel 31a to the second flow channel 31b.

[0058] Fig. 2 illustrates in a time series an example of a temperature change of the power converter 10 in a case where the temperature of the power converter 10 is measured by means of the Fig. 1 illustrated cooling device 12. Fig. 2 illustrates a water temperature Ta of the cooling water in the vicinity of the radiator 5, which is detected by the temperature sensor 16a in the first flow channel 31a, a water temperature Tb of the cooling water in a vicinity of the evaporator 6, which is detected by the temperature sensor 16b in the second flow channel 31b, a water temperature Tc of the cooling water flowing through the power converter 10, which is estimated by the temperature sensors 16a, 16b, and the outside air temperature Tair.

[0059] First, in a section T11, the heat generation amount from the first power converter 10 is relatively small, and the cooling water is circulated in the first flow channel 31a and cooled by the radiator 5.

[0060] Next, in a section T12, the flow channel of the cooling water is switched from the first flow channel 31a to the second flow channel 31b. For example, in a case where a driver depresses the accelerator pedal by a predetermined amount or more, in a case where a shift lever is shifted to a powerful driving position, and in a case where uphill driving or high-speed driving is predicted from route information such as a navigation system, it is predicted that the load of the power converter 10, the motor 11, or the storage battery 14 will become high, and their heat generation amounts will be comparatively larger than the predetermined value.Accordingly, the flow channel of the cooling water is switched from the first flow channel 31a to the second flow channel 31b, and the cooling water is cooled to the predetermined temperature or below, thereby suppressing the temperature rise of the power converter 10, the motor 11, or the storage battery 14. With this configuration, the thermal constraints of the power converter 10, the motor 11, or the storage battery 14 can be relaxed, and high power output of the power converter 10, the motor 11, or the storage battery 14 can be realized.

[0061] Specifically, in the case where the heat generation amount from the power converter 10 or the engine 11 is predicted to be greater than the predetermined value, or in the case where their heat generation amount has become large as described above, the controller 15 closes the flow rate control valve 9a of the first flow channel 31a, opens the flow rate control valve 9b of the second flow channel 31b, and circulates the cooling water in the second flow channel 31b. At this time, since the water temperature Tb of the cooling water remaining in the second flow channel 31b is lower than the water temperature Ta of the cooling water in the first flow channel 31a (see section T11), the water temperature Tc of the cooling water flowing through the power converter 10 slightly decreases.

[0062] When the compressor 1 is driven simultaneously with the driving of the above-described flow rate control valves 9a, 9b to start cooling the cooling water by the evaporator 6, the water temperature Tb of the cooling water in the second flow passage 31b and the water temperature Tc of the cooling water flowing through the power converter 10 are gradually lowered. Note that the water temperature of the cooling water can be controlled to any temperature by the controller 15. Here, since according to the refrigeration cycle system 36, a cooled body (the power converter 10 or the like) can be cooled to a temperature lower than an object to be irradiated (the outside air or the like), the cooling water can be cooled to a temperature lower than the outside temperature Tair.

[0063] In this section T12, the cooling water serving as the object to be cooled is only the cooling water in the second flow channel 31b, whose heat capacity is relatively low. Accordingly, compared with, for example, a case where all the cooling water of the water cooling system 35 is cooled, the cooling water can be quickly cooled to the predetermined temperature. Note that a dotted line Td in Fig. 2 schematically illustrates a change in the water temperature Td in a case where all the cooling water of the water cooling system 35 is cooled.

[0064] Next, in a section T13, in a case where the load of the power converter 10, the motor 11, or the storage battery 14 is reduced and their heat generation amounts are reduced, the controller 15 stops the compressor 1 of the refrigeration cycle system 36. However, in a predetermined period of time, the circulation of the cooling water in the second flow passage 31b continues, and the power converter 10, the motor 11, or the storage battery 14 is cooled by the cooling water having the relatively low temperature. With this configuration, the driving of the fan 13 attached to the radiator 5 in the first flow passage 31a is omitted, and the power consumption of the cooling device 12 can be suppressed.

[0065] Then, in a section T14, in a case where the water temperature Tb of the cooling water flowing in the second flow channel 31b rises to the water temperature Ta of the cooling water flowing in the first flow channel 31a, the flow rate control valve 9a of the first flow channel 31a is opened and the flow rate control valve 9b of the second flow channel 31b is closed. Accordingly, the cooling water is circulated again in the first flow channel 31a and subjected to cooling by the radiator 5.

[0066] Fig. 3 illustrates in a time series another example of a temperature change of the power converter 10 in a case where the temperature of the power converter 10 is measured by means of the Fig. 1 illustrated cooling device 12. In this Fig. 3, the cooling water held in the vicinity of the evaporator 6 is previously cooled by means of a standby control before the flow channel of the cooling water is shifted from the first flow channel 31a to the second flow channel 31b.

[0067] First, in a section T21, the heat generation amount of the power converter 10 is quite small, and the cooling water is circulated in the first flow channel 31a and cooled by the radiator 5.

[0068] Next, in a section T22, in a state where the flow rate control valve 9a of the first flow passage 31a is opened, the flow rate control valve 9b of the second flow passage 31b is closed, and the cooling water is circulated in the first flow passage 31a, the compressor 1 of the refrigeration cycle system 36 is driven, and the water temperature Tb of the cooling water in the vicinity of the evaporator 6 is lowered to a temperature lower than the outside air temperature Tair. As described above, it should be noted that since the flow passage of the second flow passage 31b is covered with the member 33 with high insulation performance, the power consumption of the compressor 1 for maintaining a low-temperature state can be suppressed.

[0069] Then, by switching the flow channel of the cooling water to the second flow channel 31b (a section T23) from the state of the section T22, it is possible to more quickly lower the water temperature Tb of the cooling water circulating in the second flow channel 31b and the water temperature Tc of the cooling water flowing through the power converter 10. Note that such standby control can be performed, for example, in a case where, although a high-load operation of the power converter 10, the motor 11, the storage battery 14, or the like is predicted from a tendency of the temperature rising or the like, the prediction is uncertain. By such a structure, compared to the case where switching the flow channel of the cooling water and driving the compressor 1 are performed simultaneously, for example, as shown in Fig. 2, the power consumption of the compressor 1 can be effectively suppressed. Furthermore, in a case where the low-temperature cooling water is actually required, the cooling water can be cooled to the predetermined temperature in a short time, and an output response of the power converter 10, the motor 11, or the storage battery 14 can be significantly improved.

[0070] As described above, the two flow channels 31a, 31b are provided in parallel with the power converter 10, the motor 11, or the storage battery 14 serving as the drive device of the electric drive system 40, and the radiator 5 and the evaporator 6 are connected to the respective flow channels. Accordingly, even in the case where the heat generation amount of the drive device is large, the cooling water can be cooled to the predetermined temperature in a short time, and the drive device of the electric vehicle can be cooled with good responsiveness. Therefore, the power output of the drive device can be effectively improved. [Embodiment 2]

[0071] Fig.4 illustrates a basic structure of a front interior of a vehicle to which Embodiment 2 of a cooling device according to the present invention is applied. In Embodiment 2, the above-described second flow passage 31b of the water cooling system 35 of Embodiment 1 also serves as a flow passage for heating a vehicle cabin, and the other structures are the same as those in Embodiment 1. Accordingly, the structures that are the same as those in Embodiment 1 are denoted using the same reference numerals, and detailed descriptions thereof are omitted.

[0072] In an illustrated cooling device 12A of Embodiment 2, with respect to the previously described cooling device 12 of Embodiment 1, a radiator (heat exchanger) 25 and a heating element 26 for heating a vehicle cabin are mounted on a second flow passage 31bA of a water cooling system 35A. The previously described radiator 25 is a device that heats air introduced into the vehicle cabin with warm water. Further, the previously described heating element 26 is a device that converts electricity into heat and is, for example, a heating resistor.Since the second flow channel 31bA also serves as a flow channel for heating a vehicle cabin, it should be noted that it is comparatively longer than the second flow channel 31b of Embodiment 1, and that the water amount of the cooling water flowing in the second flow channel 31bA is comparatively larger than the water amount of the cooling water flowing in the second flow channel 31b of Embodiment 1.

[0073] In an environment where the outside air temperature is low and vehicle cabin heating is required (for example, in winter), the amount of heat dissipated from surfaces or the like of a power converter 10, a motor 11, and a storage battery 14 becomes large. Therefore, it is not necessary to actually cool the power converter 10, the motor 11, and the storage battery 14 by means of a refrigeration cycle system 36, and the heat dissipated from the power converter 10, the motor 11, and the storage battery 14 can be used to heat the vehicle cabin. In other words, the cooling water heated with the heat dissipated from the power converter 10, the motor 11, and the storage battery 14 is further heated to an appropriate temperature by the heating element 26 and used as heat for heating a vehicle cabin in the heater core 25.

[0074] Note that in an environment where the outside air temperature ranges from normal temperature to high temperature and the vehicle cabin heater is not needed (e.g., in summer), a heating function is not required. Accordingly, similar to the previously described cooling device 12 of Embodiment 1, in a case where the heat generation amounts of the power converter 10, the motor 11, the storage battery 14, and the like are small, and the cooling water is cooled by circulating the cooling water in the first flow passage 31a of the water cooling system 35A, the cooling water held in the second flow passage 31bA is maintained at a comparatively low temperature.Then, in a case where the heat generation amounts of the power converter 10, the motor 11, the storage battery 14, and the like become large and it is necessary to further cool the cooling water, the flow channel of the cooling water is switched to the second flow channel 31bA, and the cooling water is circulated in the second flow channel 31bA, thereby cooling the cooling water. Immediately after the flow channel of the cooling water is switched from a first flow channel 31a to the second flow channel 31bA, a cooling water amount larger than that of the cooling device 12 of Embodiment 1 circulates there. Accordingly, the power converter 10, the motor 11, and the storage battery 14 can be cooled more quickly.

[0075] It should be noted that in the previously described embodiments 1 and 2, cooling water is used as the cooling medium in the water cooling systems 35 and 35A of the cooling devices 12 and 12A. However, oil can also be used as the cooling medium. By using oil with the characteristic of low conductivity, such an oil cooling system is capable of directly cooling the interior of the engine and also fulfilling the function of a lubricant.

[0076] Furthermore, in the previously described embodiments 1 and 2, the refrigeration cycle system 36 is used as a unit for cooling the cooling water flowing in the second flow channel. However, other units may be used as long as the unit is capable of performing heat transfer. For example, a thermocouple such as a Peltier element may be used instead of the evaporator 6 of the refrigeration cycle system 36.

[0077] Furthermore, in the above-described Embodiments 1 and 2, a description will be given regarding the structure wherein, when the heat generation amount from the power converter 10, the engine 11, or the storage battery 14 becomes large, the flow channel of the cooling water is switched from the first flow channel to the second flow channel by means of the flow rate control valves 9a and 9b. However, for example, both the flow rate control valves 9a and 9b are opened, and by adjusting their valve opening degrees, the water temperature of the cooling water flowing in the flow channels of the water cooling systems 35 and 35A can be adjusted.

[0078] Further, in the above-described Embodiments 1 and 2, a description will be given regarding the structure in which the power converter 10, the motor 11, or the storage battery 14 serving as the driving means of the electric drive system 40 is cooled. However, according to each heat generation amount, the arranged space, or the like, a cooled body that becomes an object to be cooled can be appropriately selected from the power converter 10, the motor 11, and the storage battery 14.

[0079] It should be noted that the present invention is not limited to the above-described Embodiments 1 and 2, and includes various variations. For example, the above-described Embodiments 1 and 2 are detailed descriptions for clearly describing the present invention and are not necessarily limited to those that include all of the described structures.

[0080] Furthermore, a part of the structure of one embodiment may be replaced with the structure of another embodiment, and further, the structure of the other embodiment may be added to the structure of one embodiment. Furthermore, the addition, removal, and replacement of the other structure is possible with respect to a part of the structure of each embodiment 1, 2.

[0081] Furthermore, the control lines or information lines necessary for the description are illustrated, and not all control lines and information lines are necessarily illustrated on a manufactured product. In fact, it can be assumed that almost all structures are interconnected. List of reference symbols 1 compressor 3 pressure reducers 4 Capacitor 5 coolers 6 evaporators 7 Pump 8 containers 9a, 9b Flow rate control valve (flow rate control unit) 10 power converters (cooled body) 11 Engine (cooled body) 12 Cooling device 13 Fan 14 Storage battery (cooled body) 15 Control 16a, 16b Temperature sensor 18 Refrigerant piping 25 radiators (heat exchangers) 26 Heating element 31 Flow channel of the water cooling system 31a first flow channel 31b second flow channel 31c common section 32 rubber hose 35 Water cooling system (first cooling system) 36 Refrigeration circuit system (second cooling system) 40 electric drive system 41 vehicles

Claims

[1] A cooling device (12) in which at least one of the following: a motor (11) that generates a driving force for a vehicle, a power converter (10) that controls the driving force of the motor (11), a storage battery (14) that supplies power to the power converter (10) serves as a cooled body, the cooling device (12) comprising: a first cooling system (35) which cools the cooled body by allowing a cooling medium to flow through the cooled body; and a second cooling system (36) which cools the cooling medium of the first cooling system (35) to an outside air temperature or below, wherein the first cooling system (35) comprises a first flow channel (31a) for allowing the cooling medium, which is cooled by a radiator (5) radiating the heat of the cooling medium to the outside air, to flow through the cooled body, a second flow channel (31b) for allowing the cooling medium, which is cooled to the outside air temperature or below by the second cooling system (36), to flow through the cooled body, which is provided on the first flow channel (31a), and a flow rate control unit (9a, 9b) for controlling a flow rate of the cooling medium flowing in the first flow channel (31a) and the second flow channel (31b), wherein the cooling device (12) characterized by is that the flow rate control unit (9a, 9b) comprises two flow rate control valves which can be opened simultaneously, and wherein by adjusting the valve opening degrees of the two flow rate control valves (9a, 9b), the water temperature of the cooling medium flowing in the flow channels (31a, 31b) of the first cooling system (35) can be adjusted. [2] The cooling device (12) according to claim 1, wherein the flow rate control unit (9a, 9b) changes the flow rate of the cooling medium flowing in the first flow channel (31a) and the second flow channel (31b) in response to a heat generation amount of the cooled body. [3] The cooling device (12) according to claim 2, wherein, when the heat generation amount of the cooled body becomes large, the flow rate control unit (9a, 9b) increases the flow rate of the cooling medium in the second flow channel (31b) with respect to the first flow channel (31a). [4] The cooling device (12) according to claim 1, wherein the second flow channel (31b) is covered with a member (33) having a higher insulating performance than the first flow channel (31a). [5] Cooling device (12) according to claim 1, wherein the second flow channel (31b) comprises a heat exchanger (25) for heating a vehicle cabin. [6] Cooling device (12) according to claim 1, wherein the first cooling system (35) comprises a water cooling system that uses cooling water as a cooling medium and cools the cooled body by circulating the cooling water, and the second cooling system (36) comprises a refrigeration cycle system that uses a gas-liquid phase change of a refrigerant and cools the cooling water by circulating the refrigerant, and in the first flow channel (31a) of the first cooling system (35) the cooling water is cooled by radiating the heat of the cooling medium to the outside air through the cooler (5), and in the second flow channel (31b) the cooling water is cooled by radiating the heat of the cooling water to the refrigerant of the refrigeration cycle system through an evaporator (6) of the refrigeration cycle system. [7] Cooling device (12) according to claim 6, wherein the first flow channel (31a) of the water cooling system comprises a container (8) for absorbing a volume change of the cooling water. [8] Cooling device (12) according to claim 6, wherein the evaporator (6) of the refrigeration cycle system is supported by the engine (11), the power converter (10) or the storage battery (14). [9] The cooling device (12) according to claim 6, wherein, while the circulation of the cooling water in the second flow channel (31b) is stopped, the cooling water is cooled by the evaporator (6) of the refrigeration cycle system. [10] The cooling device (12) according to claim 6, wherein, when the heat generation amount of the cooled body is greater than a predetermined value, the cooling device (12) changes the flow channel of the cooling water of the water cooling system from the first flow channel (31a) to the second flow channel (31b) by means of the flow rate control unit (9a, 9b) and circulates the cooling water in the second flow channel (31b). [11] The cooling device (12) according to claim 10, wherein in a state where a compressor (1) of the refrigeration cycle system (36) is stopped and the circulation of the cooling water in the first flow channel (31a) is stopped, the cooling device (12) circulates the cooling water in the second flow channel (31b), and after the water temperature of the cooling water in the second flow channel (31b) rises and is equal to the water temperature of the cooling water in the first flow channel (31a), the cooling device (12) starts the circulation of the cooling water in the first flow channel (31a). [12] Cooling device (12) according to claim 6, wherein the first flow channel (31a) and the second flow channel (31b) share a unit for supplying the cooling water under pressure. [13] Cooling device (12) according to claim 12, wherein the pressure supply unit is a pump (7). [14] The cooling device (12) according to claim 12, wherein the first flow channel (31a) and the second flow channel (31b) have a common portion (31c) and the pressure supply unit is provided at the common portion (31c). [15] The cooling device (12) according to claim 6, wherein the first flow channel (31a) and the second flow channel (31b) each include a temperature sensor (16a, 16b) that detects the water temperature of the cooling water circulating therein, and the flow rate control unit (9a, 9b) controls the flow rate of the cooling water flowing in the first flow channel (31a) and the second flow channel (31b) based on the temperature sensor.

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