Energy storage device and vehicle drive device

Abstract

The present invention provides a vehicle drive device having a compact configuration compared to the prior art, and an energy storage device used in the vehicle drive device. In an accumulator (25) for separating a liquid refrigerant from a gas refrigerant for cooling and heating the interior of a vehicle, heat exchange is performed between a coolant for cooling either a motor (1) for driving the vehicle or a power conversion module (5) for operating the motor (1), and at least one of the stored gas refrigerant (G) and liquid refrigerant (M).

Description

Technical Field

[0001] The invention relates to an energy storage device and a vehicle driving device. Background Art

[0002] Generally, a refrigeration cycle for air conditioning used in a vehicle has a compressor, a condenser, an expansion valve, and an evaporator as basic components. Based on such a refrigeration cycle, there is an accumulator-type refrigeration cycle in which an accumulator is arranged between the evaporator and the compressor to prevent liquid from returning to the compressor.

[0003] Patent document 1 discloses an accumulator type heat exchanger in which the heat absorption capacity caused by supercooling is increased by heat exchange between refrigerants in order to improve the refrigeration effect. The heat exchanger disclosed in patent document 1 includes a cylindrical outer shell, a cylindrical inner tank coaxially arranged in the shell, and a heat exchange passage spirally arranged in a cylindrical space between the outer shell and the inner tank. In the heat exchanger, heat is exchanged between the outgoing refrigerant flowing in the heat exchange passage in a spiral shape and the return refrigerant in the inner tank, the outgoing refrigerant is supercooled, and the return refrigerant is overheated.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2001-66022

[0005] The energy accumulator needs to be installed in a narrow space in the engine room where many devices are intricately located. For example, in automobiles that have a motor as a driving source (hybrid electric vehicles (HEV: Hybrid Electric Vehicle), plug-in hybrid electric vehicles (PHEV: Plug-in Hybrid Electric Vehicle), battery electric vehicles (BEV: Battery Electric Vehicle), fuel cell electric vehicles (FCEV: Fuel Cell Electric Vehicle), etc.), it is often installed on a vehicle drive device such as an electric shaft and mounted as an integral part. In addition, the motor integrated with the vehicle drive device and the gears that reduce the rotation of the motor are cooled by oil, and an oil cooler that performs heat exchange with cooling water is mounted. The oil cooler is also often installed on the vehicle drive device and mounted as an integral part. When both the energy accumulator and the oil cooler are installed and integrated, there is a concern that the vehicle drive device will become larger and the mountability on the vehicle will deteriorate. Summary of the invention

[0006] Therefore, a vehicle drive device and an energy storage device for the vehicle drive device that are more compact than before are desired.

[0007] One embodiment of the energy accumulator of the present invention is an energy accumulator that separates liquid refrigerant from gas refrigerant used for cooling and heating the interior of a vehicle, and performs heat exchange between a coolant that cools any one of a motor that drives the vehicle and an electric power conversion module that operates the motor, and at least one of the stored gas refrigerant and liquid refrigerant.

[0008] According to the accumulator of this embodiment, heat exchange can be performed between the coolant flowing in any one of the motor and the power conversion module and at least one of the stored gas refrigerant and liquid refrigerant, so there is no need to provide a dedicated cooling device for cooling the coolant. Or even if a cooling device is provided, the coolant is cooled by heat exchange with at least one of the gas refrigerant and liquid refrigerant stored in the accumulator, so the coolant can be sufficiently cooled using a smaller cooling device than in the past.

[0009] One embodiment of a vehicle drive device according to the present invention includes: the motor, the power conversion module, a housing that accommodates at least the motor and the power conversion module, and the energy storage device described above that is mounted on the housing.

[0010] According to the vehicle drive device of this embodiment, the energy storage device described above is provided, so there is no need to provide a cooling device in the vehicle drive device, or a small cooling device can be used. Therefore, the vehicle drive device can be configured more compactly than before. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is an exploded perspective view showing the vehicle drive device according to the first embodiment.

[0012] Figure 2 This is a block diagram showing the circuit configuration of a vehicle drive device and a heating module.

[0013] Figure 3 is a cross-sectional view of the energy storage device.

[0014] Figure 4 It is a cross-sectional view showing an accumulator according to a modified example of the first embodiment.

[0015] Figure 5 It is an exploded perspective view showing a vehicle drive device according to a second embodiment.

[0016] Figure 6 This is a block diagram showing the circuit configuration of a vehicle drive device and a heating module.

[0017] Description of Reference Numerals

[0018] 1: Electric motor (motor), 4: Housing, 5: Power conversion module, 7: Oil cooler, 25: Energy storage device, 27: Heat exchange flow path (piping unit), A: Vehicle drive device, G: Gas refrigerant, M: Liquid refrigerant. DETAILED DESCRIPTION

[0019] Hereinafter, the embodiments of the energy storage device and the vehicle drive device of the present invention are described in detail using the accompanying drawings. The energy storage device and the vehicle drive device of the present embodiment are used for automobiles (hybrid electric vehicles (HEV: Hybrid Electric Vehicle), plug-in hybrid electric vehicles (PHEV: Plug-in Hybrid Electric Vehicle), battery electric vehicles (BEV: Battery Electric Vehicle), fuel cell electric vehicles (FCEV: Fuel Cell Electric Vehicle), etc.) that have motors as driving sources. Hereinafter, the above-mentioned automobiles are collectively referred to as "electric vehicles". In addition, the embodiments described below are examples for illustrating the present invention, and the present invention is not limited to the above-mentioned embodiments. Therefore, the present invention can be implemented in various forms as long as it does not deviate from its purpose.

[0020] [First embodiment]

[0021] like Figure 1 , Figure 2 As shown, the vehicle drive device A of the first embodiment includes an electric motor 1 (an example of a motor), a gear unit 2, a power conversion module 5, an oil pump 6, a switching valve 8, a compressor 21, and an accumulator 25. In the vehicle drive device A, the electric motor 1, the gear unit 2, the power conversion module 5, the oil pump 6, and the switching valve 8 are accommodated in the housing 4 and integrated. The compressor 21 and the accumulator 25 are mounted on the side wall of the housing 4 and integrated. Integration includes a state of being fastened to the outer surface of the housing 4 by bolts or the like (hereinafter, the same).

[0022] The electric motor 1 is a driving source for the electric vehicle. The gear unit 2 decelerates and outputs the rotational driving force of the electric motor 1. The power conversion module 5 has an inverter that controls the driving current that drives the electric motor 1. That is, the vehicle drive device A outputs the rotational driving force of the electric motor 1 driven by the driving current controlled by the power conversion module 5 to the outside after decelerating the rotational driving force through the gear unit 2. The output from the vehicle drive device A is transmitted to the left and right wheels W via the differential gear 3. The compressor 21 and the accumulator 25 are used for the heating module B described later. In addition, a part of the accumulator 25 constitutes the heat exchange part D described later.

[0023] A first coolant flow path L1 in which oil (an example of coolant) for cooling the electric motor 1 and the gear unit 2 flows is arranged inside the vehicle drive device A. An example of oil is insulating oil such as paraffin. The oil pump 6 is arranged in the middle of the first coolant flow path L1, and presses the oil flowing in the first coolant flow path L1. The switching valve 8 is configured to be able to switch the flow path of the oil pressurized by the oil pump 6 between a cooling position and a non-cooling position. Specifically, in the cooling position, the oil flowing in the first coolant flow path L1 is supplied to the heat exchange part D and cooled, and then supplied to the electric motor 1 and the gear unit 2. In the non-cooling position, the oil flowing in the cooling flow path L is not cooled and is supplied to the electric motor 1 and the gear unit 2.

[0024] 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 a gas refrigerant G therein. As described above, in the heating module B, the compressor 21 and the accumulator 25 are mounted on the housing 4 of the vehicle drive device A. The heating module B is configured as a heat pump, and as the gas refrigerant G, hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), etc. can be used.

[0025] The condenser 22 is arranged in the vehicle interior. The condenser 22 has an electric blower 22a that sends warm air into the vehicle interior. The heating module B compresses the gas refrigerant G through the compressor 21 to make it high temperature and high pressure, and releases the heat energy (condensation heat) of the gas refrigerant G into the vehicle interior through the blower 22a by liquefying it in the condenser 22. As a result, the temperature in the vehicle interior is increased. The gas refrigerant G becomes liquid refrigerant M through the condenser 22.

[0026] The liquid refrigerant M passing through the condenser 22 is expanded in the expansion valve 23 and becomes low pressure, and is sent to the evaporator 24. In the evaporator 24, the liquid refrigerant M absorbs heat and evaporates. The evaporator 24 is equipped with an electric evaporation fan 24a to obtain heat energy for evaporating the liquid refrigerant M. The refrigerant that is vaporized by passing through the evaporator 24 is mostly gas refrigerant G, but contains a part of mist liquid, that is, liquid refrigerant M. The gas refrigerant G containing the liquid refrigerant M is sent to the accumulator 25.

[0027] In the accumulator 25, the gas refrigerant G containing the liquid refrigerant M supplied from the evaporator 24 is separated into gas and liquid. That is, the liquid refrigerant M is separated from the gas refrigerant G containing the liquid refrigerant M. The accumulator 25 has a vertically long cylindrical structure in order to store the liquid refrigerant M after the gas-liquid separation, and stores the liquid refrigerant M after the gas-liquid separation at the bottom. The position of the end of the refrigerant flow path R of the accumulator 25 is set so that the gas refrigerant G can be supplied to the compressor 21 from above the liquid surface of the liquid refrigerant M.

[0028] like Figure 3 As shown, the accumulator 25 is internally provided with a restriction plate 26 for reducing the pressure of the gas refrigerant G supplied from the evaporator 24. The restriction plate 26 realizes gas-liquid separation by allowing the gas refrigerant G containing the mist-like liquid refrigerant M to collide with it, and is provided to prevent the liquid refrigerant M from being blown up due to the pressure of the gas refrigerant G supplied from the evaporator 24.

[0029] The heat exchange portion D is configured to pass through the inside (inside) of the accumulator 25, and is composed of a heat exchange flow path 27 (an example of a piping unit) in which a metal pipe with high thermal conductivity is formed in a spiral shape. The heat exchange flow path 27 is configured to be immersed in the liquid refrigerant M stored in the accumulator 25. The upstream end of the heat exchange flow path 27 is connected to the switching valve 8, and the downstream end merges with the first coolant flow path L1 on the downstream side of the switching valve 8. When the switching valve 8 is switched to the cooling position, the oil flowing in the first coolant flow path L1 flows inside the heat exchange flow path 27.

[0030] Next, the flow of oil in the first coolant flow path L1 is described. The oil circulates in the first coolant flow path L1 through the oil pump 6. That is, the first coolant flow path L1 is configured to circulate the oil through the electric motor 1, the gear unit 2, the oil pump 6, the switching valve 8 and the heat exchange part D. Specifically, the oil flowing in the first coolant flow path L1 absorbs heat from the electric motor 1 and the gear unit 2 that are driven to generate heat and is heated. The heated oil is pressurized by the oil pump 6 and is delivered to the switching valve 8. When the switching valve 8 is switched to the cooling position, the oil is supplied to the inside of the accumulator 25 and flows in the heat exchange flow path 27. The oil flowing in the heat exchange flow path 27 is cooled by heat exchange with the liquid refrigerant M. The heat exchange flow path 27 is configured to be immersed in the liquid refrigerant M inside the accumulator 25 and is composed of a metal pipe with high thermal conductivity, so that heat exchange can be efficiently performed between the oil and the liquid refrigerant M. The oil cooled by the liquid refrigerant M flows out of the accumulator 25 and merges with the first coolant flow path L1 on the downstream side of the switching valve 8. The oil cooled by the heat exchanger D flows back to the electric motor 1 and the gear unit 2, and absorbs heat from the electric motor 1 and the gear unit 2 again to be heated.

[0031] When the heat generated by the electric motor 1 and the gear unit 2 is small and the oil is not heated to the degree required for heat exchange (cooling) of the heat exchange portion D, the switching valve 8 is switched to the non-cooling position. As a result, the oil flowing in the first coolant flow path L1 is not supplied to the heat exchange portion D for cooling, and flows back to the electric motor 1 and the gear unit 2 again. In addition, the switching of the switching valve 8 is performed based on the temperature of the oil detected by a temperature sensor not shown.

[0032] In this way, the vehicle drive device A of the present embodiment cools the oil heated by the heat generated by the electric motor 1 and the gear unit 2 without using an oil cooler, but by using the heat exchange portion D having the heat exchange flow path 27 configured to exchange heat with the liquid refrigerant M in the accumulator 25. Thus, an oil cooler for cooling the oil is not required, so the vehicle drive device A can be configured more compactly than before.

[0033] [Modification of the first embodiment]

[0034] Next, use Figure 4 The structure of the vehicle drive device A of the modified example of the first embodiment will be described. In this modified example, the structure of the heat exchange portion D is different from that of the first embodiment. In this modified example, the heat exchange flow path 27 constituting the heat exchange portion D is not configured to be immersed in the liquid refrigerant M stored inside the accumulator 25, but is configured to be wound around the outer periphery (outside) of the accumulator 25 and to store the liquid refrigerant M inside. Even with the heat exchange portion D configured in this way, heat exchange can be performed between the oil flowing in the heat exchange flow path 27 and the liquid refrigerant M inside the accumulator 25, and the oil can be cooled.

[0035] [Second embodiment]

[0036] Next, use Figure 5 , Figure 6 The structure of the vehicle drive device A of the second embodiment is described below. In this embodiment, unlike the first embodiment, the vehicle drive device A is provided with an oil cooler 7. In addition, the coolant flowing in the heat exchange flow path 27 is not oil but cooling water (an example of coolant). Therefore, the vehicle drive device A of this embodiment does not have a switching valve 8 for switching the first coolant flow path L1. Other than this, it has the same structure as the first embodiment. Therefore, in the description of this embodiment, the same figure marks are marked on the positions of the same structures as the first embodiment, and detailed descriptions related to the same structures are omitted.

[0037] In this embodiment, the oil cooler 7 is mounted on the power conversion module 5 and is integrated therewith and housed in the housing 4 (see Figure 5 ). Therefore, the housing 4 of this embodiment is slightly larger than that of the first embodiment.

[0038] The first coolant flow path L1 of the present embodiment is configured so that oil circulates through the electric motor 1, the gear unit 2, the oil pump 6, and the oil cooler 7. The oil flowing in the first coolant flow path L1 and the cooling water flowing in the second coolant flow path L2 are configured to perform heat exchange in the oil cooler 7. In addition, a long-life coolant (LLC) containing ethylene glycol, propylene glycol, etc. can be used as the cooling water.

[0039] like Figure 6 As shown, in the present embodiment, a radiator 9 and an electric water pump 11 are provided on the outside of the casing 4. The radiator 9 and the water pump 11 are arranged in the middle of the second coolant flow path L2. As viewed from the oil cooler 7, in the second coolant flow path L2, the water pump 11, the radiator 9, the power conversion module 5, and the heat exchange flow path 27 are arranged in the order of the water pump 11, the radiator 9, the power conversion module 5, and the heat exchange flow path 27 on the downstream side. That is, the cooling water flowing in the second coolant flow path L2 flows through the oil cooler 7, the water pump 11, the radiator 9, the power conversion module 5, and the heat exchange flow path 27, and flows back to the oil cooler 7. The heat exchange flow path 27 is a part of the second coolant flow path L2. The radiator 9 has an electric radiator fan 9a. Figure 6 In the figure, the heat exchange flow path 27 is shown as being immersed in Figure 3 The heat exchange flow path 27 is not limited to the structure of the liquid refrigerant M in the accumulator 25 as shown. Figure 3 The structure can also be Figure 4 As shown, the accumulator 25 is wound around its outer periphery and the liquid refrigerant M is stored therein.

[0040] In the present embodiment, the oil that has absorbed heat from the electric motor 1 and the gear unit 2 flows in the first coolant flow path L1 and is pressurized by the oil pump 6. Then, the oil flows into the oil cooler 7, exchanges heat with the cooling water flowing in the second coolant flow path L2 to be cooled, and then flows back to the electric motor 1 and the gear unit 2. Then, the oil absorbs heat from the electric motor 1 and the gear unit 2 again to be heated.

[0041] The cooling water heated by heat exchange with the oil in the oil cooler 7 flows in the second coolant flow path L2, and is supplied to the radiator 9 after being pressurized by the water pump 11. Furthermore, the cooling water cooled by the radiator 9 is supplied to the power conversion module 5, and is heated by absorbing the heat generated by the inverter of the power conversion module 5. Then, the heated cooling water is supplied to the inside of the accumulator 25, and flows in the heat exchange flow path 27 of the heat exchange part D. The cooling water flowing in the heat exchange flow path 27 is cooled by heat exchange with the liquid refrigerant M. The cooled cooling water flows out of the accumulator 25 and flows back to the oil cooler 7. Then, it is heated by heat exchange with the oil again.

[0042] In the past, the cooling water was directly supplied to the oil cooler 7 after being heated by the power conversion module 5. Therefore, in order to perform sufficient heat exchange between the high-temperature cooling water and the oil in the oil cooler 7, it is necessary to lengthen the flow path length where the cooling water and the oil are opposite to each other, and the oil cooler 7 will be large-scale. However, in the present embodiment, the cooling water heated by the power conversion module 5 is supplied to the heat exchange portion D formed in the accumulator 25, and is cooled by heat exchange with the liquid refrigerant M. Therefore, the temperature of the cooling water supplied to the oil cooler 7 is lower than the previous temperature, and even if the flow path length where the cooling water and the oil are opposite to each other is not increased, the required heat exchange can be performed with the oil. That is, the oil cooler 7 can use a smaller device than in the past, so the vehicle drive device A can be compactly constructed.

[0043] [Other Implementation Methods]

[0044] The present invention may be configured as follows other than the above-described embodiment and its modified example (the same reference numerals and signs as those in the embodiment are given to components having the same functions as those in the embodiment).

[0045] <1> The heat exchange portion D is formed by forming the cross section of the heat exchange flow path 27 into a non-circular shape such as an ellipse or a rectangle to increase the contact area between the heat exchange flow path 27 and the liquid refrigerant M. In addition, as a structure of the heat exchange portion D, fins for heat exchange may be provided on the outer surface of the heat exchange flow path 27 to form the heat exchange portion D.

[0046] <2> In the above-mentioned embodiment and its modified example, the coolant (oil or cooling water) flowing in the heat exchange flow path 27 exchanges heat with the liquid refrigerant M stored in the accumulator 25, but heat exchange may be performed instead of the liquid refrigerant M, or between the liquid refrigerant M and the gas refrigerant G.

[0047] <3> In the second embodiment described above, the accumulator 25 (heat exchange flow path 27) is arranged on the downstream side of the power conversion module 5, but the present invention is not limited thereto. The accumulator 25 may also be configured to be arranged on the upstream side of the power conversion module 5, that is, between the radiator 9 and the power conversion module 5. By adding the function of cooling the cooling water by the accumulator 25 to the circuit, the initial cooling capacity is improved, and the water temperature of the cooling water flowing into the oil cooler 7 is reduced. Therefore, even if the accumulator 25 is arranged on the upstream side of the power conversion module 5, the cooling performance is improved compared with the circuit without the accumulator 25.

[0048] In the above-described embodiment of the accumulator 25 and the vehicle drive device A, the following configurations are conceivable.

[0049] (1) One embodiment of the accumulator 25 is an accumulator 25 that separates liquid refrigerant M from gas refrigerant G used for cooling and heating the interior of a vehicle, and performs heat exchange between a coolant that cools any one of a motor (electric motor 1) that drives the vehicle and an electric power conversion module 5 that operates the motor, and at least one of the stored gas refrigerant G and liquid refrigerant M.

[0050] In the accumulator 25 of the present embodiment, heat exchange can be performed between the coolant (oil or cooling water) flowing in any one of the motor (electric motor 1) and the power conversion module 5 and at least one of the gas refrigerant G and the liquid refrigerant M stored in the accumulator 25, so there is no need to provide a dedicated cooling device for cooling the coolant. Or even if a cooling device is provided, the coolant is cooled by heat exchange with at least one of the gas refrigerant G and the liquid refrigerant M stored in the accumulator 25, so the coolant can be sufficiently cooled using a small cooling device compared to the past.

[0051] (2) In the accumulator 25 described in (1), it is preferable that the oil as the coolant for cooling the motor (electric motor 1 ) is cooled by performing heat exchange.

[0052] Thus, the oil is cooled by exchanging heat with at least one of the gas refrigerant G and the liquid refrigerant M stored in the accumulator 25. Therefore, the oil cooler 7 is unnecessary.

[0053] (3) In the accumulator 25 described in (1) or (2), it is preferable that the coolant flows inside the pipe unit (heat exchange flow path 27) arranged on the inner side or the outer side.

[0054] Thus, the coolant flows inside the piping unit (heat exchange flow path 27) that performs heat exchange inside or outside the accumulator 25, and is cooled by performing heat exchange with at least one of the gas refrigerant G and the liquid refrigerant M stored in the accumulator 25.

[0055] (4) In the accumulator 25 described in (3), it is preferable that the pipe unit (heat exchange flow path 27) is arranged so as to be immersed in the liquid refrigerant M on the inside.

[0056] When the piping unit (heat exchange flow path 27 ) is arranged so as to be immersed in the liquid refrigerant M inside the accumulator 25 , the coolant directly exchanges heat with the liquid refrigerant M via the piping unit (heat exchange flow path 27 ), so that heat exchange can be performed efficiently.

[0057] (5) In the accumulator 25 described in (4), it is preferable that the pipe unit (heat exchange flow path 27) is formed in a spiral shape.

[0058] (6) In the accumulator 25 described in (3), it is preferable that the pipe unit (heat exchange flow path 27) is arranged so as to be wound around the position where the liquid refrigerant M is stored on the outside.

[0059] When the piping unit (heat exchange flow path 27) is configured to be wound around the outside of the accumulator 25 at a position where the liquid refrigerant M is stored, there is no need to configure the piping unit (heat exchange flow path 27) inside (inside) the accumulator 25, so a structure for performing heat exchange with the liquid refrigerant M can be easily obtained.

[0060] (7) One embodiment of the vehicle drive device A comprises: a motor (electric motor 1), a power conversion module 5, a housing 4 that at least accommodates the motor (electric motor 1) and the power conversion module 5, and an energy storage device 25 described in any one of the above (1) to (6) mounted on the housing 4.

[0061] According to the vehicle drive device A of this embodiment, the energy storage device 25 described in any one of (1) to (6) above is provided, so that it is not necessary to provide a cooling device for the vehicle drive device A, or a small cooling device can be used. Therefore, the vehicle drive device A can be constructed more compactly than before.

[0062] (8) The vehicle drive device A described in (7) preferably also includes an oil cooler 7, which performs heat exchange between cooling water serving as a coolant for cooling the power conversion module 5 and oil serving as a coolant for cooling the motor (electric motor 1). After the cooling water is cooled by heat exchange in the energy accumulator 25, heat exchange is performed with the oil in the oil cooler 7.

[0063] In the past, in order to perform sufficient heat exchange between the cooling water and the oil through the oil cooler 7, it was necessary to increase the length of the flow path where the cooling water and the oil face each other, and the oil cooler 7 would be large. However, in this structure, the cooling water heated by the power conversion module 5 is cooled by heat exchange with at least one of the gas refrigerant G and the liquid refrigerant M stored in the accumulator 25. Therefore, the temperature of the cooling water supplied to the oil cooler 7 is lower than the previous temperature, and even if the length of the flow path where the cooling water and the oil face each other is not increased, the required heat exchange can be performed with the oil. That is, the oil cooler 7 can use a smaller device than in the past, so the vehicle drive device A can be constructed more compactly than in the past.

[0064] [Possibility of Industrial Application]

[0065] The present invention can be used in an energy storage device and a vehicle driving device.

Claims

1. An accumulator for separating liquid refrigerant from gaseous refrigerant used for cooling and heating a vehicle cabin, characterized in that: Heat is exchanged between a coolant that cools any one of a motor that drives the vehicle and a power conversion module that operates the motor and at least one of the stored gas refrigerant and the stored liquid refrigerant.

2. The energy storage device according to claim 1, characterized in that The oil as the coolant for cooling the motor is cooled by heat exchange.

3. The energy storage device according to claim 1 or 2, characterized in that: The coolant flows inside the pipe unit arranged inside or outside.

4. The energy storage device according to claim 3, characterized in that: The pipe unit is arranged so that the inner side is immersed in the liquid refrigerant.

5. The energy storage device according to claim 4, characterized in that: The pipe unit is formed in a spiral shape.

6. The energy storage device according to claim 3, characterized in that: The pipe unit is disposed so as to be wound around the outer side at a position where the liquid refrigerant is stored.

7. A vehicle driving device, characterized in that: have: The motor, the power conversion module, a housing for accommodating at least the motor and the power conversion module, and the energy storage device according to claim 1 or 2 mounted on the housing.

8. The vehicle driving device according to claim 7, characterized in that: Also available: an oil cooler that performs heat exchange between cooling water as the cooling liquid for cooling the power conversion module and oil as the cooling liquid for cooling the motor, The cooling water is cooled by heat exchange in the accumulator and then exchanges heat with the oil in the oil cooler.

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