Heat exchange system

Abstract

To provide a heat exchange system which can increase a temperature in a cabin in a short time even in a cold area.SOLUTION: A heat exchange system includes: a vehicle drive unit A including at least an electric motor 1 which transmits drive rotational force to a traveling system of a vehicle and a cooling passage L in which a coolant for cooling the electric motor 1 circulates; and a heating module B which heats a cabin of the vehicle. The heating module B has a refrigerant flow passage R for circulating a gaseous refrigerant obtained by gas-liquid separation in an accumulator 25 through a compressor 21, a condenser 22, and an expansion valve 23 in a written order. The heat exchange system includes a heat exchange part D which applies heat of the coolant circulating the cooling passage L to the refrigerant of the accumulator 25.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat exchange system. [Background technology]

[0002] Taking as an example a vehicle drive unit (referred to as a vehicle drive device in the literature) that transmits drive torque to the vehicle's running system, Patent Document 1 shows a configuration that enables a vehicle to run using the drive force of an electric motor (referred to as a rotating electric machine in the literature). This vehicle drive unit has a drive configuration in which an electric motor, an input member, and a counter gear are housed in a case, and drive force from the counter gear is transmitted to the wheels via a differential gear mechanism.

[0003] The vehicle drive unit (vehicle drive device) of Patent Document 1 shows an oil passage that supplies oil to a coil end portion of an electric motor (rotating electric machine), a rotor shaft oil passage in the internal space of a cylindrical rotor shaft of the electric motor, and the like, and also supplies oil to an oil cooler. The vehicle drive unit of Patent Document 1 also shows a cooling water passage that sends cooling water in the following order: an inverter module outside the case, a case that is the outer wall of the electric motor, an oil cooler, and a radiator.

[0004] In this way, the vehicle drive unit of Patent Document 1 makes it possible to cool the entire device by removing heat from the electric motor, inverter module, etc. using oil and coolant.

[0005] It is desirable to efficiently air-condition the cabin of a vehicle. The engine-driven heat pump device described in Patent Document 2 does not include a vehicle drive unit, but shows a refrigerant circuit having a compressor driven by a water-cooled engine, an exterior heat exchanger, and an interior heat exchanger.

[0006] Patent Document 2 discloses an accumulator that is supplied with refrigerant from a suction side circuit of a refrigerant circuit, and stores liquid refrigerant in the accumulator. This refrigerant circuit includes a hot water pipe (third hot water pipe) inside the accumulator to enable heat exchange between the liquid refrigerant and cooling water, and discloses a circuit for enabling heat exchange with the liquid refrigerant.

[0007] In the configuration of Patent Document 2, when the cooling load is large, heat exchange with a liquid phase refrigerant is performed to ensure subcooling, and when the cooling load is small, heat exchange with cooling water (heated by engine cooling) is performed to ensure superheating. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2022-30847 [Patent Document 2] JP 2000-234822 A Summary of the Invention [Problem to be solved by the invention]

[0009] The vehicle drive unit (vehicle drive device) described in Patent Document 1 achieves cooling by removing heat generated by an electric motor (rotating electric machine) with oil and water.

[0010] Here, one can imagine a heat pump type air conditioning system that aims to raise the temperature inside the vehicle cabin by circulating refrigerant through the compressor, condenser, expansion valve, and evaporator in that order.

[0011] In this way, in a heat pump type air conditioning system, when the driver first gets into the vehicle in cold regions, it is necessary to raise the temperature inside the cabin quickly, but the thermal energy obtained by the evaporator may be insufficient, and it may take time for the temperature to rise even if the amount of refrigerant circulating is increased.

[0012] For these reasons, there is a demand for a heat exchange system that can raise the temperature inside the cabin in a short period of time, even in cold regions. [Means for solving the problem]

[0013] The characteristic configuration of the heat exchange system of the present invention is that it comprises a vehicle drive unit including at least an electric motor that transmits drive rotational force to the vehicle's running system and a cooling flow path through which a coolant that cools the electric motor flows, and a heating module that heats the cabin of the vehicle, wherein the heating module has a refrigerant flow path that circulates gaseous refrigerant obtained by gas-liquid separation in an accumulator through a compressor, a condenser, and an expansion valve, in that order, and is equipped with a heat exchange section that gives heat of the coolant flowing through the cooling flow path to the refrigerant in the accumulator.

[0014] According to this configuration, when heating is performed by the heating module, the gaseous refrigerant in the accumulator is compressed by the compressor and then flows into the condenser, where heat is released, thereby raising the temperature inside the cabin. The vehicle drive unit has a cooling flow path through which a coolant that cools the electric motor flows, and the heat of the coolant flowing through the cooling flow path is transferred to the refrigerant in the accumulator by the heat exchanger, so that the refrigerant with increased thermal energy is supplied to the compressor, eliminating the shortage of thermal energy. As a result, a heat exchange system has been configured that can raise the temperature inside the cabin in a short time, even in cold regions. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a block circuit diagram showing a heat exchange system. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a block circuit diagram of a control configuration. [Figure 4] FIG. 4 is a block circuit diagram showing a heat exchange system according to another embodiment (a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of a heat exchange system S in an electric vehicle having a vehicle drive unit A will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0017] [Basic configuration] The electric vehicle includes a vehicle drive unit A shown in FIG. 1, a heating module B, and a heat exchange system S that provides thermal energy of a coolant of the vehicle drive unit A to the heating module B.

[0018] The vehicle drive unit A drives the wheels W using current supplied from a battery. Examples of electric vehicles include automobiles equipped with an electric motor 1 as a driving source for traveling, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell electric vehicles (FCEVs).

[0019] The vehicle drive unit A accommodates an electric motor 1, a gear unit 2, a differential gear 3, and a cooling module C in a drive case 4. This vehicle drive unit A includes an inverter 5 outside the drive case 4 that controls power from a battery (not shown) consisting of a secondary battery and supplies it to the electric motor 1.

[0020] In addition, a battery 42 is shown in another embodiment (a) (see FIG. 4) described later, and in the another embodiment (a), a configuration that enables cooling of the battery 42 is described.

[0021] The electric motor 1 transmits rotational driving force to the driving system of the electric vehicle. That is, the vehicle driving unit A reduces the driving force of the electric motor 1 by the gear unit 2 and transmits it to the left and right wheels W through the differential gear 3.

[0022] The cooling module C uses, as a coolant, cooling water such as long-life coolant (LLC) containing ethylene glycol or propylene glycol, or insulating oil such as paraffin-based oil.

[0023] As shown in Fig. 1, the accumulator 25 is provided in a state of being integrated with the drive case 4 of the vehicle drive unit A. "Integrated" refers to a state in which it is fastened to the outer surface of the drive case 4 with bolts or the like (hereinafter the same). The accumulator 25 has a space for storing a refrigerant in its internal space, and is provided with a heat exchange section D in this internal space.

[0024] The drive case 4 houses an electric oil pump 6 that sends oil as a coolant, an oil cooler 7 (indicated as O / C in the drawings) that enables the oil to be cooled, and a switching valve 8 that controls the flow of oil. The switching valve 8 is configured to be freely switchable between a warm-up position where the coolant in the cooling flow path L is supplied to the heat exchange unit D, and a cooling position where the coolant in the cooling flow path L is supplied to the oil cooler 7.

[0025] [Cooling module] The cooling module C has a cooling flow path L that circulates oil (an example of a coolant) by an oil pump 6. The cooling flow path L is configured to enable the circulation of oil to the electric motor 1, the gear unit 2, a switching valve 8, the heat exchanger D, and the oil cooler 7. The switching valve 8 enables switching between a state in which the oil supplied from the oil pump 6 is supplied to the heat exchanger D, and a state in which the oil is supplied to the oil cooler 7 without being supplied to the heat exchanger D.

[0026] In the drive case 4, a cooling passage L for flowing a part of the oil is formed in the stator (core part) where the coil of the electric motor 1 is arranged, and a cooling passage L for flowing a part of the oil is formed inside the shaft of the electric motor 1. As the oil flows through these cooling passages L, heat generated by the electric motor 1 is removed and the temperature of the oil is increased.

[0027] Furthermore, the oil that has flowed into the cooling passage L of the electric motor 1 is supplied to the multiple gears of the gear unit 2 from the cooling passage L inside the drive case 4. As a result of this supply, the temperature of the oil increases due to the heat of the gear unit 2, and the oil lubricates the gear unit 2. This oil is temporarily stored in the bottom of the drive case 4.

[0028] 1, the drive case 4 is provided with a radiator 9 on the outside of the drive case 4. The radiator 9 controls the amount of cooling water flowing from a cooling water passage 10 to the oil cooler 7 by driving an electric water pump 11. The radiator 9 is provided with an electric radiator fan 9a.

[0029] As a result, the coolant removes heat from the oil flowing in the cooling passage L via the oil cooler 7 and releases it from the coolant in the radiator 9, suppressing the rise in temperature of the electric motor 1. Note that a long-life coolant (LLC) containing ethylene glycol, propylene glycol, or the like is used as the coolant.

[0030] [Heating module] The heating module B includes an electric compressor 21, a condenser 22, an expansion valve 23, an evaporator 24, an accumulator 25, and a refrigerant flow path R that circulates the refrigerant through these components. The heating module B is configured as a heat pump, and uses hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), or the like as the refrigerant. The compressor 21, in addition to the accumulator 25, may also be integrated into the drive case 4.

[0031] The condenser 22 is disposed in the cabin and includes an electric blower 22a that blows out the air heated by the condenser 22. The heating module B compresses a gaseous refrigerant by the compressor 21 and liquefies the refrigerant in the condenser 22, thereby releasing the thermal energy of the refrigerant and increasing the temperature in the cabin.

[0032] The refrigerant that has passed through the condenser 22 expands in the expansion valve 23 and evaporates due to the heat absorption by the evaporator 24, storing thermal energy in the refrigerant. The evaporator 24 is equipped with an electric evaporation fan 24a to obtain thermal energy for evaporating the refrigerant. The refrigerant that has passed through the evaporator 24 is sent to the accumulator 25.

[0033] The accumulator 25 has a vertically long cylindrical structure for storing the refrigerant supplied from the evaporator 24 in a gas-liquid separated state, and the liquid refrigerant is stored at the bottom. In the accumulator 25, the position of the end of the refrigerant flow path R is set so that the gaseous refrigerant can be supplied to the compressor 21 from above the liquid level of the refrigerant.

[0034] As shown in FIG. 2, the accumulator 25 separates gas and liquid refrigerants by collision of the refrigerant, and includes therein a regulating plate 26 that weakens the pressure of the refrigerant supplied from the evaporator 24 so as to prevent the liquid refrigerant from being blown up due to the pressure of the refrigerant supplied from the evaporator 24.

[0035] The heat exchange section D has a heat exchange passage 27 formed by forming a metal pipe having high thermal conductivity into a spiral shape. The heat exchange passage 27 is disposed inside the accumulator 25 and immersed in the liquid refrigerant.

[0036] [Heat exchange system] The heat exchange system S is configured to provide thermal energy contained in the coolant flowing through the cooling flow passage L of the cooling module C to the refrigerant in the accumulator 25 of the heating module B.

[0037] In the cooling module C of the vehicle drive unit A, thermal energy is provided from the electric motor 1 to the coolant in the cooling flow path L. In addition, the accumulator 25 provides the thermal energy of the coolant to the refrigerant as the coolant flows through the heat exchange flow path 27 of the heat exchange section D. As a result, the heat exchange system S enables an increase in the thermal energy supplied to the compressor 21.

[0038] [Control configuration] As shown in Fig. 3, the electric vehicle includes a control device 30 that controls the heating module B. The control device 30 has a microprocessor, a DSP (digital signal processor), etc., and functions as an ECU (electronic control unit).

[0039] This control device 30 receives signals from a heating switch 31, a cabin temperature sensor 32, and an oil temperature sensor 33.

[0040] The control device 30 outputs control signals to each of the switching valve 8, the oil pump 6, the water pump 11, the radiator fan 9a, the compressor 21, the blower 22a, and the evaporation fan 24a.

[0041] The cooling module C is originally designed to lower the temperature of the oil flowing through the cooling flow path L by the oil cooler 7. In contrast to this, when attempting to raise the temperature inside the cabin in cold regions or the like, the heat exchange system S supplies oil whose temperature has been raised by heat generated by the electric motor 1 during driving to the heat exchange section D via the switching valve 8, thereby increasing the thermal energy of the refrigerant stored in the accumulator 25 and raising the temperature inside the cabin in a short period of time.

[0042] For this reason, when a rapid increase in cabin temperature is required, the control device 30 operates the compressor 21 when the heating switch 31 is turned ON, and when the temperature detected by the cabin temperature sensor 32 is below the set value, the control device 30 sets the switching valve 8 to the warm-up position and starts blowing air using the blower 22a.

[0043] By executing this control, the heating module B liquefies the refrigerant compressed by the compressor 21 in the condenser 22, and as a result of this liquefaction, the temperature of the condenser 22 is increased, and the heated air is supplied into the cabin by the blower 22a.

[0044] In addition, when the thermal energy of the gaseous refrigerant supplied to the compressor 21 is small (when the temperature detected by the cabin temperature sensor 32 is lower than a set value), such as when the electric vehicle is in a cold region, the control device 30 sets the switching valve 8 to the warm-up position, thereby supplying oil with an increased temperature to the heat exchange section D, and the thermal energy of the refrigerant stored in the accumulator 25 is increased by heat exchange in this heat exchange section D.

[0045] By configuring the control form in this manner, when the rotation speed of the compressor 21 is increased to increase the amount of refrigerant supplied, it is possible to produce air at the temperature required by the condenser 22 without a shortage of thermal energy contained in the gas-like refrigerant.

[0046] Thereafter, if the cabin temperature sensor 32 detects that the temperature inside the cabin has reached the set value, the control device 30 stops the compressor 21 (or may reduce the rotation speed) and switches the switching valve 8 to the cooling position, thereby suppressing heating.

[0047] After the temperature inside the cabin has risen to the set value, the control device 30 sets the switching valve 8 to the cooling position, drives the water pump 11, and drives the radiator fan 9a, so that the heat of the oil flowing through the cooling passage L is absorbed by the cooling water via the oil cooler 7, thereby suppressing the temperature rise of the electric motor 1 and the gear unit 2.

[0048] [Effects of the embodiment] In this way, the heating module B heats the cabin by the gaseous refrigerant in the accumulator 25 flowing through the compressor 21 and the condenser 22 and dissipating heat in the condenser 22. In the cooling module C of the vehicle drive unit A, the temperature of the oil circulating through the cooling flow path L increases as the electric motor 1 is driven. To utilize this phenomenon, the heat exchange system S transfers the heat of the oil to the refrigerant in the accumulator 25 via the heat exchanger D.

[0049] As a result, the refrigerant has stored thermal energy when it is supplied to the compressor 21, and the amount of heat required to increase the temperature is not insufficient, enabling an efficient increase in the temperature inside the cabin. Specifically, even if the rotation speed of the compressor 21 is increased, sufficient thermal energy allows the temperature inside the cabin to increase in accordance with the rotation speed.

[0050] Since the heat exchange section D is equipped with a heat exchange flow passage 27 formed by forming a tubular material into a spiral shape, when the cooling liquid flows, heat is exchanged with the refrigerant through a wide surface area, realizing efficient heat exchange.

[0051] After flowing through the evaporator 24, the refrigerant is supplied from the end of the refrigerant flow path R to the internal space of the accumulator 25 without disturbing the liquid level of the refrigerant due to the regulation by the regulating plate 26, thereby preventing the inconvenience of liquid refrigerant droplets being sent to the compressor 21.

[0052] [Another embodiment] The present invention may be configured as follows other than the above-described embodiment (common numbers and symbols as in the embodiment are used to designate components having the same functions as in the embodiment).

[0053] (a) As shown in FIG. 4, the electric vehicle accommodates part of a heating module B and part of a cooling unit F inside a drive case 4, and has a condenser 22 constituting the heating module B and an evaporator 41 constituting the cooling unit F outside the drive case 4.

[0054] In this electric vehicle, a battery 42 that supplies current to the electric motor 1 is disposed outside the drive case 4, and a chiller 43 that enables cooling of the battery 42 is integrated into the drive case 4. The chiller 43 has a cooling circuit that supplies coolant to the battery 42. The cooling circuit is equipped with an electric circulation pump 44 that circulates the coolant.

[0055] The condenser 22 and the evaporator 41 are provided at positions that enable air conditioning inside the cabin. The condenser 22 aims to increase the temperature inside the cabin during heating, and the evaporator 41 aims to decrease the temperature inside the cabin during cooling.

[0056] The vehicle drive unit A of this alternative embodiment (a) is provided with one accumulator 25 for a refrigerant flow path R that enables heating and cooling. The accumulator 25 is provided in a state of being integrated into the drive case 4 of the vehicle drive unit A. In addition to the accumulator 25, the compressor 21 is also integrated into the drive case 4.

[0057] In this alternative embodiment (a), similarly to the above-described embodiment, the heat exchange system S provides thermal energy contained in the oil flowing through the cooling flow passage L of the cooling module C to the refrigerant in the accumulator 25 via the heat exchange section D. In this manner, the heat exchange system S increases the thermal energy of the refrigerant supplied to the compressor 21, thereby efficiently increasing the temperature inside the cabin.

[0058] The vehicle drive unit A of another embodiment (a) includes a cooling water passage 10 that supplies cooling water for cooling the oil cooler 7 to a power supply module 12 and a water-cooled condenser 13, and an electromagnetic flow path selection valve 14 that controls the flow of cooling water to the radiator 9. The power supply module 12 includes a circuit unit that controls the current supplied to the electric motor 1, and is cooled by the cooling water. The water-cooled condenser 13 reduces the temperature of the refrigerant that has flowed through an expansion valve 23.

[0059] 4, like the above-described embodiment, the accumulator 25 has a space therein for storing a refrigerant, and includes a regulating plate 26 and a heat exchanger D. The cooling module C includes a switching valve 8 that can be switched between a warm-up position for supplying the cooling liquid flowing through the cooling flow passage L to the heat exchanger D, and a cooling position for adjusting the supply of the cooling liquid to the oil cooler 7.

[0060] The refrigerant flow path R is provided with an electromagnetic flow path control valve 40 downstream of the water-cooled condenser 13. The flow path control valve 40 is configured to be freely switchable between a direct connection position where the refrigerant sent out from the water-cooled condenser 13 is directly supplied to the accumulator 25, and a branching position where the refrigerant is branched into a branch flow path.

[0061] A cooling-side expansion valve 45 is provided upstream of the evaporator 41 in the refrigerant flow path R to which the refrigerant is supplied by setting the flow path control valve 40 to the branch position, and a cooling-side expansion valve 46 is provided upstream of the chiller 43. The expansion valve 23, the cooling-side expansion valve 45, and the cooling-side expansion valve 46 are disposed outside the drive case 4.

[0062] When heating the cabin, the vehicle drive unit A sets the flow path control valve 40 to the direct connection position and operates the compressor 21 to heat the cabin. Furthermore, when it is necessary to rapidly increase the temperature inside the cabin, such as in cold regions, the switching valve 8 can be set to the warm-up position to supply oil with a raised temperature to the heat exchange section D. This increases the thermal energy of the refrigerant stored in the accumulator 25 by heat exchange in the heat exchange section D, making it possible to produce air at the required temperature in the condenser 22.

[0063] In addition, when air-conditioning the cabin or cooling the battery 42, the vehicle drive unit A sets the flow path control valve 40 to the branch position and operates the compressor 21 to achieve air-conditioning by supplying cold air from the evaporator 41 into the cabin, and cools the battery 42 by supplying refrigerant to the battery 42.

[0064] (b) The drive case 4 is configured so that the inverter 5 can be cooled by supplying cooling water, and oil whose temperature has increased due to the heat of the electric motor 1 and the heat of the inverter 5 is supplied to the heat exchange section D.

[0065] In particular, in this alternative embodiment (b), the temperature of the oil flowing through the cooling passage L can be increased not only by the heat generated by the electric motor 1 but also by the heat generated by the inverter 5, so that the temperature inside the cabin can be increased quickly.

[0066] (c) The cross section of the heat exchange passage 27 is formed in a non-circular shape such as an ellipse or a rectangle to expand the contact area between the heat exchange passage 27 and the refrigerant. Furthermore, the heat exchange section D is configured by providing fins for heat exchange on the outer surface of the heat exchange passage 27.

[0067] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention.

[0068] In the embodiment of the heat exchange system described above, the following configurations are envisaged. (1) The vehicle drive unit A includes an electric motor 1 that transmits drive torque to the vehicle's running system, and a cooling flow path L through which a coolant for cooling the electric motor 1 flows, and a heating module B that heats the vehicle's cabin. The heating module B has a refrigerant flow path R that circulates a gaseous refrigerant obtained by gas-liquid separation in an accumulator 25 through a compressor 21, a condenser 22, and an expansion valve 23 in that order, and is equipped with a heat exchange section D that gives heat of the coolant flowing through the cooling flow path L to the refrigerant in the accumulator 25.

[0069] According to this characteristic configuration, when heating is performed by the heating module B, the gaseous refrigerant in the accumulator 25 flows to the compressor 21 and the condenser 22, and dissipates heat in the condenser 22, making it possible to increase the temperature inside the cabin. The cooling module C provides the thermal energy of the coolant, the temperature of which has increased as the electric motor 1 is driven, to the refrigerant in the accumulator 25 by the heat exchanger D. This makes it possible to supply the refrigerant with increased thermal energy to the compressor 21, eliminating the shortage of thermal energy for increasing the temperature.

[0070] (2) In (1), it is preferable that the heat exchange section D has a tubular heat exchange passage 27 for flowing a cooling liquid disposed in the internal space of the accumulator 25.

[0071] According to this, the heat of the cooling liquid flowing through the heat exchange passage 27 is given to the refrigerant in the internal space of the accumulator 25, and the heat is not wasted.

[0072] (3) In (2), it is preferable that the heat exchange passage 27 is disposed in a state of being immersed in the liquid refrigerant stored in the accumulator 25.

[0073] According to this, the thermal energy of the heat exchange passage 27 is directly transferred to the refrigerant, realizing good heat exchange.

[0074] (4) In (1) to (3), it is preferable that the accumulator 25 is integrated into the vehicle drive unit A.

[0075] This configuration can shorten the distance between the cooling flow path L of the vehicle driving unit A and the accumulator 25, for example, compared to a configuration in which the accumulator 25 is provided at a position away from the vehicle driving unit A. This makes it possible to shorten the flow path for supplying and discharging the coolant to the heat exchange section D, suppressing heat radiation to the atmosphere and improving heat exchange efficiency. [Industrial Applicability]

[0076] The present invention can be used in a heat exchange system. [Explanation of symbols]

[0077] 1: electric motor, 21: compressor, 22: condenser, 23: expansion valve, 25: accumulator, 27: heat exchange flow path, A: vehicle drive unit, B: heating module, D: heat exchange section, L: cooling flow path, R: refrigerant flow path, S: heat exchange system

Claims

1. A vehicle drive unit includes at least an electric motor that transmits a drive torque to a running system of a vehicle and a cooling flow path through which a coolant for cooling the electric motor flows, and a heating module that heats a cabin of the vehicle, The heating module has a refrigerant flow path that circulates a gaseous refrigerant obtained by gas-liquid separation in an accumulator through a compressor, a condenser, and an expansion valve in this order, a heat exchange unit that provides heat of the cooling liquid flowing through the cooling flow passage to the refrigerant in the accumulator;

2. The heat exchange system according to claim 1 , wherein the heat exchange portion has a tubular heat exchange passage for flowing the cooling liquid, the tubular heat exchange passage being disposed in the internal space of the accumulator.

3. The heat exchange system according to claim 2 , wherein the heat exchange passage is disposed in a state of being immersed in the liquid refrigerant stored in the accumulator.

4. The heat exchange system according to any one of claims 1 to 3, wherein the accumulator is integrated into the vehicle drive unit.

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