JP2024079082A - Cooling System - Google Patents

Abstract

To provide a cooling system having high assemblability and improved radiation efficiency.SOLUTION: A cooling system A includes: a pair of side frames 14b, 14b arranged so as to sandwich a battery pack arranged under a floor; and a radiator 27 arranged in front of a vehicle. The side frames 14b, 14b include an energy absorption part 25 functioning as an impact relaxation member extending in a front and rear direction of the vehicle in a state of projecting in a right and left direction of the vehicle. A space 26 formed in the inside of the energy absorption part 25 has formed therein a cooling flow path B through which cooling fluid circulates to the radiator 27.SELECTED DRAWING: Figure 2

Description

The present invention relates to a cooling system.

Conventionally, in vehicles such as electric vehicles, a technology has been known in which the drive unit, which is made up of a motor and a transaxle, is supported by a rear side member in order to provide the rotational driving force of the drive unit to the rear wheels (see, for example, Patent Document 1).

In the vehicle described in Patent Document 1, a battery pack is placed in the space under the floor of the passenger compartment, and the battery pack is supported via a cross member that is suspended between side members.

JP 2021-133837 A

When the drive unit is supported by the rear side member, as in the vehicle described in Patent Document 1, a cooling flow path needs to be formed along the side member in order to circulate the cooling fluid that has dissipated heat via the radiator to the drive unit, which requires the routing of piping. As a result, it is necessary to sacrifice the efficiency of heat dissipation from the piping in terms of ease of installation, and there is also room for improvement in terms of ease of assembly.

Therefore, there is a demand for a cooling system that is easy to assemble and has high heat dissipation efficiency.

The cooling system according to the present invention is characterized in that it comprises a pair of side frames arranged to sandwich a battery pack arranged under the floor, and a radiator arranged at the front of the vehicle, the side frames having an energy absorbing section that functions as a collision mitigating member extending in the front-rear direction of the vehicle while protruding in the left-right direction of the vehicle, and a cooling flow path that circulates a cooling fluid to the radiator is formed in the space formed inside the energy absorbing section.

In this configuration, the side frame is provided with an energy absorbing section that functions as a collision mitigation member, which can prevent damage to the battery pack in the event of a collision. By effectively utilizing the space formed inside this energy absorbing section to function as a cooling flow path that circulates cooling fluid to the radiator, no piping is required, improving ease of assembly.

In addition, the energy absorption section has a large surface area to function as a collision mitigation member, so the cooling fluid circulated in the energy absorption section dissipates a large amount of heat into the atmosphere, making it possible to reduce the heat dissipation load on the radiator. This results in a cooling system that is easy to assemble and has high heat dissipation efficiency.

Another characteristic configuration is that the system further includes an electric vehicle drive unit that includes at least an electric motor that transmits drive torque to the rear wheels of the vehicle, and the cooling flow path circulates the cooling fluid between the electric vehicle drive unit and the radiator.

Even if an electric motor that generates a large amount of heat is placed at the rear of the vehicle as in this configuration, the electric vehicle drive unit can be cooled without the need for piping thanks to the cooling flow path formed in the internal space of the energy absorbing section.

Another characteristic feature is that the space formed inside the energy absorbing section is divided into an inner space on the side of the battery pack and an outer space on the outside of the vehicle, and the cooling flow path is provided with a switching valve that can be switched between a first state in which the cooling fluid is circulated through the inner space and a second state in which the cooling fluid is circulated through the outer space.

By providing a switching valve as in this configuration, for example, during warm-up operation of the battery, warm cooling fluid that has been given the waste heat of the electric vehicle drive unit can be circulated through a flow path provided in the inner space to provide heat to the battery (first state), while cold cooling fluid flowing from the radiator to the electric vehicle drive unit can be circulated through a flow path provided in the outer space (second state).

For example, when it is desired to cool a battery, cold cooling fluid flowing from the radiator to the electric vehicle drive unit can be circulated through a flow path provided in the inner space to cool the battery (first state), while warm cooling fluid flowing from the electric vehicle drive unit to the radiator can be circulated through a flow path provided in the outer space (second state).

Another characteristic feature is that the space formed inside the energy absorbing section is divided into an inner space on the side of the battery pack and an outer space on the outside of the vehicle, and the cooling flow path is formed only in the inner space.

The cooling flow passage in this configuration is provided only in the inner space, which is less deformed during a collision, so the heat dissipation efficiency of the cooling fluid flowing through the cooling flow passage can be maintained even in the event of an unexpected collision or other event.

FIG. 1 is a plan view of a vehicle underbody structure including a cooling system according to a first embodiment; 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 4 is a cross-sectional view showing a modified example of the first embodiment. FIG. 11 is a plan view of a vehicle underbody structure including a cooling system according to a second embodiment. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5 . FIG. 11 is a cross-sectional view showing a modified example of the second embodiment.

Below, an embodiment of the cooling system according to the present invention 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.

First Embodiment
An electric vehicle includes an electric vehicle drive unit that drives wheels with a current supplied from a battery. Examples of electric vehicles include automobiles equipped with a motor as a drive 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).

The vehicle underbody structure 10 shown in Figures 1 and 2 is a structure for mounting a battery pack 23 and an electric vehicle drive unit 2 (hereinafter referred to as the "vehicle drive unit 2") on the vehicle body, and is formed under the vehicle body. The vehicle underbody structure 10 includes a pair of front side members 11F, 11F and rear side members 11R, 11R provided on both the front and rear sides of the vehicle body, and a battery frame 13. The battery frame 13 is provided to support the battery pack 23 arranged under the floor, and also functions as a floor side member. Hereinafter, the front side members 11F, 11F will be abbreviated as "side members 11F, 11F", and the rear side members 11R, 11R will be abbreviated as "side members 11R, 11R".

At the front of the vehicle, a pair of suspension towers 18 are fixed to the side members 11F, 11R, and the front wheels 3 are positioned on the vehicle outer side of the suspension towers 18. At the rear of the vehicle, a pair of suspension towers 18 are fixed to the side members 11R, 11R via rear suspension members, and the rear wheels 4 are positioned on the vehicle outer side of the suspension towers 18.

The vehicle body including the side members 11F, 11F and the side members 11R, 11R is mainly made of steel. On the other hand, the battery frame 13 is made of, for example, aluminum.

The vehicle drive unit 2 includes at least an electric motor 21 that transmits a drive torque to the rear wheels 4 of the vehicle. Specifically, the vehicle drive unit 2 includes the electric motor 21, a gear (not shown) with a reduction mechanism, and the like. The vehicle drive unit 2 is supported by being attached to a suspension member (not shown) arranged on the vehicle body side.

The battery pack 23 is mainly used to drive an electric vehicle. The battery pack 23 is generally flat, and is configured by electrically connecting a number of battery modules (not shown) made up of a number of horizontally arranged battery cells (not shown) and housing them in a battery case or the like. Note that the battery pack 23 may also be made up of a number of battery cells without modularizing them, and is not particularly limited.

In this embodiment, the battery frame 13 is integrally formed with the extension frames 15, 16. Specifically, the battery frame 13 has a battery housing section 14 that supports the battery pack 23, and is configured with a first extension frame 15 that extends from the battery housing section 14 toward the front side of the vehicle body, and a second extension frame 16 that extends from the battery housing section 14 toward the rear side of the vehicle body.

The battery storage section 14 has a bottom surface 14a on which the battery pack 23 is placed, and a pair of side walls 14b, 14b (an example of a side frame) provided on the left and right sides of the bottom surface 14a. A partition may be provided on the bottom surface 14a of the battery storage section 14 according to the shape of the battery pack 23 (e.g., the shape of the battery module). In this embodiment, the side walls 14b of the battery storage section 14 are exemplified as side sills, but side sills may be provided separately from the battery storage section 14.

The first extension frame 15 is provided between the side members 11F, 11F. The first extension frame 15 has a bottom surface portion 15a, a pair of side wall portions 15b, 15b provided along the side members 11F, 11F, continuing from the side wall portions 14b, 14b of the battery storage portion 14, and a front wall portion 15c provided across the side wall portions 15b, 15b at the front end side of the first extension frame 15. The bottom surface portion 15a is provided with a rib-shaped partition portion 15d formed in the left-right direction of the vehicle body. The second extension frame 16 is provided between the side members 11R, 11R. The second extension frame 16 has a bottom surface portion 16a, a pair of side walls 16b, 16b that are continuous with the side walls 14b, 14b of the battery storage portion 14 and are provided along the side members 11R, 11R, and a rear wall portion 16c that is provided across the side walls 16b, 16b at the rear end side of the second extension frame 16. The bottom surface portion 16a is provided with a rib-shaped partition portion 15d that is formed in the left-right direction of the vehicle body.

In this embodiment, in the battery frame 13, the side walls 16b, 16b of the second extension frame 16 are configured to function as suspension members, but the rear wall 16c and the rear partition 16d adjacent to the battery frame 13 may also be defined as the suspension member. For example, the width between the side walls 16b, 16b is set to a width that allows the vehicle drive unit 2 to be assembled and supported. This allows the vehicle drive unit 2 to be supported by the side walls 16b, 16b.

In this embodiment, the member supporting the vehicle drive unit 2 is composed of a second extension frame 16 that is integrally formed with the battery frame 13. In other words, the support function of the vehicle drive unit 2 is integrated into the battery frame 13, and the battery pack 23 and vehicle drive unit 2, which are heavy objects, are supported.

As shown in Figures 1 and 2, the side wall portion 14b of the battery frame 13 has an energy absorbing portion 25 that extends in the front-rear direction of the vehicle while protruding in the left-right direction of the vehicle. The energy absorbing portion 25 functions as a collision mitigation member for the vehicle. The energy absorbing portion 25 is made of aluminum, for example. The energy absorbing portion 25 has a space 26 formed therein that extends in the front-rear direction of the vehicle body.

As shown in FIG. 3, the space 26 of the energy absorbing section 25 is made up of a plurality of spaces 26 that are partitioned in the left-right direction of the vehicle body and extend in the front-rear direction of the vehicle body. In this embodiment, the plurality of spaces 26 are made up of seven spaces 26a to 26g. Here, the spaces 26a to 26g are formed in order from the side closest to the battery pack 23 in the left-right direction of the vehicle body, with the first space 26a to the seventh space 26g being formed.

Figure 2 shows an example of a cooling system A provided in an electric vehicle. The cooling system A includes a pair of side walls 14b, 14b of the battery frames 13 and a radiator 27, and a cooling flow path B that circulates a cooling fluid to the radiator 27 is formed in the space 26 of the energy absorbing section 25. Cooling fluid such as antifreeze mainly composed of ethylene glycol, long-life coolant, cooling water, insulating oil, etc. flows through the cooling flow path B.

As shown in FIG. 2, the radiator 27 is disposed in front of the vehicle. Specifically, the radiator 27 is disposed in front of the first extension frame 15. The cooling flow path B includes at least the radiator 27 and a water pump (not shown) in the middle of the flow path, and is configured to circulate the cooling fluid to the radiator 27 and the object to be cooled. In this embodiment, the vehicle drive unit 2 is disposed in the middle of the cooling flow path B, and the cooling fluid is configured to circulate between the vehicle drive unit 2 and the radiator 27. The cooling flow path B is formed in the space 26 formed inside the energy absorption section 25. The cooling flow path B has a first flow path 41 from the radiator 27 toward the vehicle drive unit 2, and a second flow path 42 from the vehicle drive unit 2 toward the radiator 27.

The first flow path 41 has a flow path 41a from the radiator 27 to the energy absorbing section 25, a flow path 41b formed inside the energy absorbing section 25, and a flow path 41c from the energy absorbing section 25 toward the vehicle drive unit 2. The second flow path 42 has a flow path 42a from the vehicle drive unit 2 to the energy absorbing section 25, a flow path 42b formed inside the energy absorbing section 25, and a flow path 42c from the energy absorbing section 25 toward the radiator 27.

In this embodiment, as shown in FIG. 3, the flow paths 41b and 42b are formed by the second space 26b to the seventh space 26g of the energy absorbing section 25. The first space 26a is used for joining with the bottom surface 14a of the battery housing 14. Specifically, the end 14a1 of the bottom surface 14a of the battery housing 14 is fixed to the bottom surface 26a1 of the first space 26a of the energy absorbing section 25 by fastening members 28 such as bolts and nuts. In addition, fastening members 29 such as bolts and nuts that penetrate vertically and extend upward are fixed to the fifth space 26e, and the side wall 14b is fixed to the upper part of the fastening members 29.

In this embodiment, the energy absorbing section 25, which functions as a collision mitigation member, is disposed at the bottom of the side wall section 14b of the battery frame 13 and is made part of the side frame, so that damage to the battery pack 23 can be prevented in the event of a collision. By effectively utilizing the space 26 formed inside this energy absorbing section 25 and having it function as a cooling flow path B that circulates cooling fluid to the radiator 27, no piping is required, and assembly can be improved.

In addition, the energy absorbing section 25 has a large surface area so that it can function as a collision mitigation member, and therefore the cooling fluid circulated through the energy absorbing section 25 dissipates a large amount of heat into the atmosphere, making it possible to reduce the heat dissipation load of the radiator 27. In this way, this embodiment provides a cooling system A that is easy to assemble and has high heat dissipation efficiency.

In addition, even if the vehicle drive unit 2, which includes the electric motor 21 that generates a large amount of heat, is placed at the rear of the vehicle as in this embodiment, the vehicle drive unit 2 can be cooled by the cooling flow path B formed in the space 26 inside the energy absorption section 25 without the need for piping.

[Modification of the first embodiment]
As shown in FIG. 4, the space 26 of the energy absorbing section 25 is divided into an inner space C on the side of the battery pack 23 and an outer space D on the outside of the vehicle. In the example shown in FIG. 4, the inner space C is formed by the spaces 26b to 26d, and the outer space D is formed by the spaces 26e to 26g. In this modification, the cooling flow path B provided in the energy absorbing section 25 is formed only in the inner space C. Therefore, in the energy absorbing section 25, the cooling fluid flows only in the inner space C, and does not flow in the outer space D. In this manner, the cooling flow path B in this modification is provided only in the inner space C, which is less deformed during a collision, so that the heat dissipation efficiency of the cooling fluid flowing through the cooling flow path B can be maintained even in an unexpected event such as a collision.

Second Embodiment
As shown in Fig. 5 and Fig. 6, in the second embodiment, as in the modified example of the first embodiment, the space 26 formed inside the energy absorbing section 25 is divided into an inner space C (spaces 26b, 26c, 26d) on the side of the battery pack 23 and an outer space D (spaces 26e, 26f, 26g) on the outside of the vehicle. However, the second embodiment differs from the first embodiment in the following respects. In the second embodiment, one of the inner space C and the outer space D is configured to be usable as the cooling flow path B. In addition, the cooling flow path B is provided with a switching valve 31 (three-way valve) that can be switched between a first state in which the cooling fluid is circulated through the inner space C and a second state in which the cooling fluid is circulated through the outer space D. The other configurations are the same as those of the first embodiment.

In this embodiment, the switching valve 31 is composed of a first switching valve 31a arranged in the flow path 41a of the first flow path 41 and a second switching valve 31b arranged in the flow path 42a of the second flow path 42. In the example shown in Figures 5 and 6, the outer space D is selected as the flow path 41b, and the inner space C is selected as the flow path 42b.

If the switching valve 31 is provided as in this configuration, for example, during warm-up operation of the battery (battery pack 23), as shown in Figures 5 and 6, warm cooling fluid that has been given the waste heat of the vehicle drive unit 2 can be circulated through the flow path 42b provided in the inner space C to give heat to the battery pack 23 (first state), and cold cooling fluid flowing from the radiator 27 toward the vehicle drive unit 2 can be circulated through the flow path 41b provided in the outer space D (second state).

Although not shown in the figure, the inner space C may be selected as the flow path 41a, and the outer space D may be selected as the flow path 42b. In this case, for example, when it is desired to cool the battery (battery pack 23), the cold cooling fluid flowing from the radiator 27 to the vehicle drive unit 2 can be circulated through the flow path 41b provided in the inner space C to cool the battery (first state), and the warm cooling fluid flowing from the vehicle drive unit 2 to the radiator 27 can be circulated through the flow path 42b provided in the outer space D (second state).

[Modification of the second embodiment]
The inner space C and the outer space D that configure the cooling flow path B may be configured by a part of the multiple spaces 26a to 26g of the energy absorbing section 25. In the example shown in Fig. 7, of the second space 26b to the fourth space 26d that are located inside (on the side of the battery pack 23) in the left-right direction of the vehicle body from the fifth space 26e, the second space 26b is configured as the inner space C, and the fourth space 26d is configured as the outer space D.

In this manner, in this modified example, the cooling flow path B provided in the energy absorbing section 25 is formed on the side of the battery pack 23 relative to the fifth space 26e to which the side wall section 14b is fixedly supported in the left-right direction of the vehicle body. That is, in this modified example, as in the modified example of the first embodiment, the cooling flow path B is provided in the inner space in the left-right direction of the vehicle body, which is less deformed during a collision, so that the heat dissipation efficiency of the cooling fluid flowing through the cooling flow path B can be maintained even in the event of an unexpected event such as a collision.

Other Embodiments
(1) In the above embodiment, an example has been described in which the first space 26a in the energy absorbing section 25 is not used as the cooling flow path B, but the first space 26a may be used as the cooling flow path B. In addition, the multiple spaces 26 (spaces 26a to 26g) partitioned in the energy absorbing section 25 may be appropriately selected and used as the cooling flow path B.
(2) In the above embodiment, the vehicle drive unit 2 is cooled by the cooling passage B. However, the cooling passage B may be configured to cool a power supply unit disposed at the rear of the vehicle. The cooling passage B may also be connected to a heat sink that cools the battery pack 23.
(3) In the above embodiment, an example was shown in which only the vehicle drive unit 2 that drives the rear wheels 4 is arranged at the rear of the vehicle, but a configuration in which a vehicle drive unit 2 that drives the front wheels 3 is separately provided at the front of the vehicle is also possible.
(4) In the above embodiment, an example was shown in which the suspension member was fixed to a frame that extended the battery frame 13. Alternatively, the suspension member may be fixed to a pair of side members and provided independently of the battery frame.

This invention can be widely used in cooling systems for electric vehicles.

2: Electric vehicle drive unit 4: Rear wheel 14: Battery storage section 14b: Side wall section (side frame)
21: Electric motor 23: Battery pack 25: Energy absorbing portion 26: Space 27: Radiator 31: Switching valve A: Cooling system B: Cooling passage C: Inner space D: Outer space

Claims (4)

A pair of side frames arranged to sandwich a battery pack arranged under the floor;
a radiator disposed at the front of the vehicle;
The side frame has an energy absorbing portion that functions as a collision mitigating member extending in a front-rear direction of the vehicle while protruding in a left-right direction of the vehicle,
A cooling system in which a cooling flow path for circulating a cooling fluid to the radiator is formed in a space formed inside the energy absorbing section. The vehicle further includes an electric vehicle drive unit including at least an electric motor that transmits a drive torque to a rear wheel of the vehicle.
The cooling system according to claim 1 , wherein the cooling passage circulates the cooling fluid between the electric vehicle drive unit and the radiator. The space formed inside the energy absorbing portion is partitioned into an inner space on the side of the battery pack and an outer space on the outside of the vehicle,
The cooling system according to claim 1 or 2, wherein the cooling passage is provided with a switching valve that can be switched between a first state in which the cooling fluid is circulated through the inner space and a second state in which the cooling fluid is circulated through the outer space. The space formed inside the energy absorbing portion is partitioned into an inner space on the side of the battery pack and an outer space on the outside of the vehicle,
The cooling system according to claim 1 or 2, wherein the cooling passage is formed only in the inner space.

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