Cooling structure for vehicle-mounted battery

Abstract

Provided is a cooling structure for a vehicle-mounted battery, whereby a battery pack can be efficiently cooled with a simple configuration, a rise in temperature of the battery pack can be prevented, and battery performance can be maintained, and in addition, a variation in temperature among a plurality of battery packs can be suppressed, and output restrictions and accelerated battery degradation can be avoided.　The cooling structure for the vehicle-mounted battery is for cooling a battery mounted under the floor of a vehicle. The battery has a plurality of battery packs arranged along the front-rear direction of the vehicle. A first air flow passage through which cooling air (traveling wind) introduced from the front of the vehicle flows is formed above the plurality of battery packs. A second air flow passage through which the traveling wind introduced from the front of the vehicle flows is formed at the lower side of the plurality of battery packs, and a cooling air flow passage through which the cooling air introduced from the first air flow passage flows is formed in each arrangement gap between the plurality of battery packs. A negative pressure suctioning part that draws air into the cooling air flow passages by a negative pressure suctioning action generated by the flow velocity of the traveling wind is formed in the second air flow passage.

Description

Cooling structure for vehicle batteries

[0001] The present invention relates to a cooling structure for an in-vehicle battery.

[0002] Conventionally, in vehicles equipped with a high-voltage battery as a power source, the temperature rise of the battery module during charging and discharging is relatively significant, and therefore a cooling structure is usually provided to prevent this temperature rise. One cooling structure for such an in-vehicle battery uses air cooling by the wind while the vehicle is running (see Patent Document 1). For example, for all-solid-state batteries, which are relatively heat-resistant among batteries, it is desirable to use air cooling by the wind while the vehicle is running, which is effective in terms of weight reduction and cost reduction, without relying on the relatively strong cooling capacity of a water-cooling system.

[0003] Patent No. 5494584

[0004] However, with conventional air-cooling using the wind while the vehicle is moving, the front battery packs are often cooled more easily because they are directly exposed to outside air, while the rear battery packs are more difficult to cool because they are exposed to air heated by the battery packs further forward. As a result, the battery packs that are more difficult to cool are less able to maintain their performance. Furthermore, temperature variations between multiple battery packs can lead to output limitations and accelerate battery degradation.

[0005] Furthermore, because the battery packs (on-board batteries) installed in vehicles are relatively large, they are often installed under the floor or outside the vehicle. It is difficult to install devices such as blowers in such locations. Therefore, when using air cooling from the vehicle's running wind, there is a need for a method of efficiently cooling the battery pack without relying on devices such as blowers.

[0006] The present invention has been proposed to address these circumstances, and aims to provide a cooling structure for an on-board battery that can efficiently cool a battery pack with a simple configuration, thereby preventing the battery pack from rising in temperature and maintaining battery performance, and suppressing temperature variations between multiple battery packs, thereby avoiding output restrictions and accelerated battery deterioration.

[0007] The cooling structure for an on-board battery of the present invention is a structure for cooling a battery mounted under the floor of a vehicle, the battery having a plurality of battery packs arranged along the longitudinal direction of the vehicle, a first air passage formed above the plurality of battery packs through which travelling wind as cooling air introduced from the front of the vehicle flows, a second air passage formed below the plurality of battery packs through which travelling wind introduced from the front of the vehicle flows, a cooling air passage formed in the gaps between the plurality of battery packs through which the cooling air introduced from the first air passage flows, and a negative pressure suction section formed in the second air passage that draws air into the cooling air passage by a negative pressure suction effect generated by the flow speed of the travelling wind.

[0008] According to the present invention, it is possible to provide a cooling structure for an on-board battery that can efficiently cool a battery pack with a simple configuration, thereby preventing the temperature of the battery pack from rising and maintaining battery performance, and suppressing temperature variations between multiple battery packs, thereby avoiding output restrictions and accelerated battery deterioration.

[0009] FIG. 1 is a schematic partial side view showing an example of a part of a vehicle equipped with a battery cooling structure of a first embodiment. FIG. 2 is a schematic side view showing an example of a battery cooling structure of a first embodiment. FIG. 3 is a schematic partial top view showing an example of the configuration of a beam member and a thermally conductive material in a cooling air passage. FIG. 4 is a schematic side view showing an example of a battery cooling structure of a second embodiment. FIG. 5 is a schematic side view showing an example of a battery cooling structure of a third embodiment. FIG. 6 is a schematic side view showing an example of a battery cooling structure of a fourth embodiment. FIG. 7 is a schematic side view showing an example of the configuration of a pressure release valve formed by attaching an opening / closing door to a pressure release hole. FIG. 8 is a schematic top view showing an example of the configuration of a second air passage in a battery cooling structure of a fifth embodiment. FIG. 9 is a schematic side view showing an example of the battery cooling structure of a fifth embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, the same configuration will not be described.

[0011] In each drawing, the direction indicated by arrow X (hereinafter also referred to as the "X direction") is the forward direction in the fore-and-aft direction of vehicle A (vehicle traveling direction), the direction indicated by arrow Y (hereinafter also referred to as the "Y direction") is the rightward direction in the width direction (left-right direction) of vehicle A, and the direction indicated by arrow Z (hereinafter also referred to as the "Z direction") is the upward direction in the up-and-down direction (height direction) of vehicle A. The opposite direction of the X direction is the backward direction in the fore-and-aft direction of vehicle A (vehicle rearward direction), the opposite direction of the Y direction is the leftward direction in the width direction of vehicle A, and the opposite direction of the Z direction is the downward direction in the up-and-down direction (height direction) of vehicle A.

[0012] In each figure, the front side is the side closer in the X direction (more forward), and the rear side is the side closer in the opposite direction of the X direction (more rearward). The right side is the side closer in the Y direction (more rightward), and the left side is the side closer in the opposite direction of the Y direction (more leftward). The upper side is the side closer in the Z direction (more upward), and the lower side is the side closer in the opposite direction of the Z direction (more downward). Furthermore, front, rear, left, right, and up and down refer to front and rear in the vehicle fore-and-aft direction of vehicle A, left and right in the vehicle width direction of vehicle A, and up and down in the vertical direction (height direction) of vehicle A. Furthermore, the front of vehicle A in the vehicle fore-and-aft direction is simply referred to as the "front," and the rear of vehicle A in the vehicle fore-and-aft direction is simply referred to as the "rear."

[0013] Of the multiple battery packs 22 included in the battery 2 described below, the battery pack 22 located furthest forward in the vehicle longitudinal direction is also referred to as the "front battery pack 22." The battery pack 22 adjacent to the front battery pack 22 and located toward the center in the vehicle longitudinal direction is also referred to as the "center battery pack 22." The battery pack 22 adjacent to the center battery pack 22 and located furthest rearward in the vehicle longitudinal direction is also referred to as the "rear battery pack 22."

[0014] First Embodiment First, a cooling structure 1 for an in-vehicle battery (battery cooling structure) according to a first embodiment of the present invention will be described. Fig. 1 shows a portion of a vehicle A equipped with the battery cooling structure 1 according to the first embodiment. The battery cooling structure 1 is a structure for cooling a battery 2 mounted under the floor of the vehicle A. The vehicle A is an electric vehicle (EV), which is an example of a vehicle powered by the battery 2. However, the vehicle A is not limited to this, and may be any other vehicle having a battery as a power source, such as a hybrid vehicle or a fuel cell vehicle.

[0015] As shown in FIG. 1 , seats 5, including a driver's seat, are provided on a floor panel 4 within a vehicle body 3 of vehicle A, and a steering wheel 6 and other components for driving are provided in front of the seats 5. A front section 7 of the vehicle body 3 is provided with an engine, a motor, a heat exchanger (radiator), an electronic control unit (ECU), and other components (not shown). The vehicle body 3 also has a front grille opening (air inlet) 8 located at its very front. Outside air (traveling wind) is blown into the front grille opening 8 from the front of the vehicle A while the vehicle A is traveling as cooling air for cooling a battery 2 (described below). Note that "traveling" refers to a state in which the vehicle A is traveling forward (in the vehicle travel direction, X direction).

[0016] 1 and 2 , the vehicle body 3 has an upper underfloor section 9 located below the floor panel 4, and a lower underfloor section (undercover) 10 located below the upper underfloor section 9 and horizontal in the front-rear and left-right directions. The battery 2 is located in the space under the floor of the vehicle A, between the upper underfloor section 9 and the lower underfloor section 10. The battery 2 is configured to include a junction box (JB) 21 and multiple battery packs (front, center, and rear battery packs) 22 located rearward of the junction box (JB).

[0017] The plurality of battery packs 22 are arranged along the longitudinal direction of the vehicle A and have the same or substantially the same configuration. In the example shown in Figures 1 and 2, three battery packs 22 having substantially the same configuration are arranged at intervals along the longitudinal direction of the vehicle.

[0018] As shown in FIG. 2, the junction box (JB) 21 is located at the frontmost side of the battery 2 in the vehicle longitudinal direction, and is configured to include a junction box (JB) main body 21b inside a junction box (JB) case (housing) 21a.

[0019] The JB main body 21b is connected to the JB case 21a via a fixing member 21c. The configuration and material of the fixing member 21c are not particularly limited. The JB main body 21b supplies high voltage to an inverter that drives the drive motor, a DC-DC converter that converts high voltage to 12V and supplies it to various 12V-based electric components of the vehicle, and an air conditioner, heater, and other devices (none of which are shown) installed in the vehicle body 3. During charging, the JB main body 21b supplies charging power from a charger (not shown) to battery cells 22b of the battery pack 22 (described later).

[0020] In this example, one battery pack 22 includes a battery case 22a and, for example, ten battery cells 22b housed therein. In each battery pack 22, a fixing member 22c is provided within the battery case 22a. In each battery pack 22, ten battery cells 22b are provided on the fixing member 22c (FIG. 3). The ten battery cells 22b within the battery case 22a are arranged parallel to one another at regular or approximately regular intervals (at a regular or approximately regular pitch) in the left-right direction (Y direction) perpendicular or approximately perpendicular to the main flow of the running wind. Furthermore, in each battery pack 22, the ten battery cells 22b are connected to the battery case 22a via fixing members 22d on the side surfaces. The configuration and material of the fixing members 22c are not particularly limited. The fixing members 22d are preferably thermally conductive, and may be, for example, a metal plate or an adhesive containing thermally conductive particles.

[0021] In one battery pack 22 shown in this example, ten battery cells 22b are housed in the battery case 22a in this state. The battery 2 has three battery packs 22 arranged at intervals from one another in the vehicle longitudinal direction, resulting in a total of 30 battery cells 22b arranged at intervals from one another. Note that the number of battery cells 22b arranged in the left-right direction in one battery pack 22 is not limited to ten and may be one or more. Furthermore, the number of battery packs 22 arranged in the vehicle longitudinal direction in the battery 2 is not limited to three and may be any number more than one.

[0022] The battery cell 22b is, for example, an all-solid-state battery cell. The all-solid-state battery cell is formed by mixing and solidifying powder of active material for the positive and negative electrodes with powder of a solid electrolyte, and is a battery cell that can operate at high temperatures and can adjust its temperature within the temperature range of the wind when the vehicle is running. However, the battery cell 22b is not limited to this and may be a cell of another battery, for example, a lithium-ion battery cell.

[0023] A first air passage 11 is formed above the battery 2 having multiple battery packs 22. The first air passage 11 is formed by a floor tunnel that forms a space between the floor panel 4 and the upper underfloor section 9. While the vehicle A is traveling, traveling wind as cooling air introduced from the front of the vehicle A through the front grill opening 8 flows in the vehicle rearward direction through the first air passage 11. An air layer is formed between the upper underfloor section 9 and the battery 2. As a result, heat from the battery 2 is not transferred to the first air passage 11. Therefore, the cooling wind (traveling wind) flowing through the first air passage 11 maintains a sufficient cooling effect (cooling capacity) without being affected by the heat of the battery 2 (particularly the battery cells 22b).

[0024] 1 and 2, a plurality of protrusions 9a are formed in the underfloor upper portion 9 along the vehicle longitudinal direction, protruding into the first air passage 11. Each of the protrusions 9a has an opening (not shown) that connects to the first air passage 11. The protrusions 9a are formed above a cooling air passage 13, which will be described later.

[0025] A second air passage 12 through which airflow introduced from the front of the vehicle A flows is formed below the battery 2. The second air passage 12 is formed by the space between the battery 2 and the underfloor lower portion 10.

[0026] A plurality of cooling air passages 13 are formed within the battery 2, through which the cooling air (driving air) introduced from the first air passage 11 flows. The cooling air passages 13 are formed in the gap between the junction box (JB) 21 of the battery 2 and the front battery pack 22, as well as in the gaps between the array of the plurality of battery packs 22 (between the front, central, and rear battery packs 22) and on the rear surface side of the rear battery pack 22. In this way, a plurality of cooling air passages 13 are arranged in the fore-and-aft direction of the vehicle. As an example, the cooling air passages 13 may be hollow portions with nothing provided inside.

[0027] Within second air passage 12, a plurality of negative pressure suction sections 14 are formed in the vehicle longitudinal direction, which draw air into cooling air passage 13 by a negative pressure suction effect generated by the flow speed of the air as the vehicle travels. These negative pressure suction sections 14 are formed by extending cooling air passage 13 shown in Figure 2 downward, and are air passages located within second air passage 12 (see the area enclosed by dotted lines in Figure 2).

[0028] The floor panel 4 is configured to slope downward from the front side to the rear side. Therefore, the cross-sectional area of ​​the floor tunnel constituting the first air passage 11 gradually narrows from the front side to the rear side, and the flow velocity (wind speed) of the cooling air (traveling air) flowing from the front side to the rear side gradually increases. As a result, in the first air passage 11, as the cooling air flows into each cooling air passage 13, the flow rate (air volume) of the cooling air gradually decreases from the front side to the rear side of the first air passage 11, but the flow velocity gradually increases. Therefore, in the first air passage 11, the flow rate of the cooling air flowing therein is uniform from the front side to the rear side, and the flow rate of the cooling air flowing from the first air passage 11 to the cooling air passage 13 is also uniform from the front side to the rear side.

[0029] 1 and 2, a portion of the cooling air (driving air) flowing in the vehicle rearward direction through first air passage 11 is drawn into cooling air passage 13 below underfloor upper portion 9 through an opening (not shown) in protruding portion 9a by the negative pressure suction action of negative pressure suction portion 14, and flows downward through cooling air passage 13. The cooling air flowing through cooling air passage 13 is introduced directly from first air passage 11 and is not affected by the heat of battery 2 (particularly battery cell 22b), and therefore has a sufficient cooling effect (cooling capacity).

[0030] Here, the negative pressure suction effect of the negative pressure suction unit 14 will be described. The second air passage 12 is narrowed at the location where the negative pressure suction unit 14 is provided. Therefore, at that location, the cross-sectional area of ​​the flow of road air flowing through the second air passage 12 in the vehicle reverse direction is narrowed due to the Venturi effect, increasing the flow velocity (wind speed) and reducing the wind pressure, resulting in negative pressure. The negative pressure generated within the second air passage 12 causes the negative pressure suction unit 14 to draw (pull in) the cooling air (road air) in the cooling air passage 13 into the second air passage 12 as cooling exhaust air.

[0031] The negative pressure suction section 14 draws the cooling air (driving air) in the cooling air passage 13 into the second air passage 12 as cooled exhaust air by using a negative pressure suction action based on the Venturi effect caused by the flow speed of the driving air flowing through the second air passage 12 in the direction of the vehicle's rearward movement, thereby sufficiently drawing the cooling air flowing through the first air passage 11 into the cooling air passage 13.

[0032] In the battery cooling structure 1, the cooling air in the first air passage 11, which has such a sufficient cooling effect, is drawn into each of the plurality of cooling air passages 13 arranged in the battery 2 by the negative pressure suction action of the negative pressure suction section 14 in the battery 2. That is, as shown by the solid arrow in Fig. 1 , when cooling air (traveling air) is introduced from the outside into the front portion 7 of the vehicle body 3 through the front grill opening (air inlet) 8, while the cooling air flows in the rearward direction of the vehicle through the first air passage 11, a portion of the cooling air is drawn into the cooling air passage 13 through an opening (not shown) in a protrusion 9a formed in the upper underfloor portion 9 shown in Fig. 2 by the negative pressure suction action of the negative pressure suction section 14.

[0033] As a result, the cooling air (traveling air) drawn into the cooling air passage 13 flows forcefully downward within the cooling air passage 13. Sufficient heat exchange occurs between the cooling air flowing through the cooling air passage 13 and the battery cells 22b within the battery pack 22, thereby cooling the battery pack 22.

[0034] The cooling air (traveling air) drawn into the cooling air passage 13 flows through the cooling air passage 13 and is then introduced (drawn) as cooling exhaust air into the common second air passage 12. In the second air passage 12, the traveling air drawn from the front and the cooling exhaust air drawn from the cooling air passage 13 both flow in the vehicle rearward direction within the second air passage 12 and are then discharged from the downstream end of the second air passage 12 to the outside of the vehicle A.

[0035] In the battery cooling structure 1 of the first embodiment, the Venturi effect causes a negative pressure suction action generated by the flow velocity (wind speed) of traveling air flowing through the second air passage 12, thereby drawing cooling air (traveling air) that is not affected by the heat of the battery cells 22b directly into the cooling air passage 13 from the first air passage 11. As a result, the battery cooling structure 1 allows the cooling air drawn into the cooling air passage 13 to sufficiently cool the battery cells 22b in the battery pack 22 adjacent to the cooling air passage 13. That is, the battery cooling structure 1 allows each of the multiple battery packs 22 included in the battery 2 to be sufficiently cooled by the cooling air (traveling air) drawn directly from the first air passage 11 into the cooling air passage 13, regardless of its position in the vehicle longitudinal direction, such as the front, center, or rear. The battery cooling structure 1 thus provides a sufficiently high cooling effect on the battery cells 22b due to the cooling air (traveling air).

[0036] As described above, the battery cooling structure 1 of the first embodiment can efficiently cool the battery cells 22b included in each of the multiple battery packs 22 in the battery 2 with a simple configuration in which the negative pressure suction unit 14 is provided in the second air passage 12. This makes it possible to prevent a temperature rise in the battery packs 22 and maintain battery performance in the battery cooling structure 1. At the same time, the battery cooling structure 1 can suppress temperature variations among the multiple battery packs 22 included in the battery 2, thereby avoiding output limitations and accelerated battery degradation.

[0037] 1 and 2, the cooling air passage 13, fixing members 21c, and fixing members 22d may be replaced with the configuration shown in the example of Fig. 3. In the example of Fig. 3, the cooling air passage 13 is formed of beam members 31, and the battery cells 22b are fixed to the beam members 31 by thermally conductive materials 32 connected to the beam members 31. The ten battery cells 22b included in one battery pack 22 are each connected at their ends in the X direction and the opposite direction to the thermally conductive materials 32. The thermally conductive materials 32 are then connected to the beam members 31.

[0038] The beam members 31 constituting the cooling air passage 13 are made of a heat-conductive material and have a plurality of spaces 31a as multiple spaces that penetrate vertically (in the Z direction and the opposite direction). The heat-conductive material forming the beam members 31 is not particularly limited, but may be, for example, aluminum or an aluminum alloy, and the beam members 31 may be made of, for example, an aluminum extrusion material.

[0039] The thermally conductive material 32 may be, for example, a thermally conductive connecting material, such as an adhesive containing thermally conductive particles.

[0040] In the example of Fig. 3 , the cooling air (traveling air) flowing through the first air passage 11 is drawn into the plurality of spaces 31a in the cooling air passage 13 (beam members 31) by the negative pressure suction action of the negative pressure suction section 14, and then flows downward (opposite the Z direction) through the plurality of spaces 31a before being drawn into the second air passage 12. In the example of Fig. 3 , more sufficient heat exchange occurs between the cooling air (traveling air) flowing downward through the plurality of spaces 31a in the cooling air passage 13 and the battery cells 22b via the beam members 31 and the thermal conductive material 32, which are made of thermal conductive material. As a result, in the example of Fig. 3 , a higher cooling effect can be obtained for the battery cells 22b.

[0041] 1 and 2, a temperature control (cooling) plate such as a water-cooled plate (not shown) may be provided. In each battery pack 22 in the battery 2, by providing the above-mentioned ten battery cells 22b on a temperature control (cooling) plate such as a water-cooled plate (not shown), a higher cooling effect can be obtained for the battery cells 22b.

[0042] For example, when vehicle A is traveling, the battery cells 22b may be cooled by this temperature regulation (cooling) plate in addition to the cooling of the battery cells 22b by the above-mentioned traveling wind. Alternatively, when vehicle A is traveling, the battery cells 22b may not be cooled by this temperature regulation (cooling) plate, but may be cooled only by the above-mentioned traveling wind. When vehicle A is stopped (such as when battery 2 is being charged), the traveling wind cannot be obtained, so the battery cells 22b may be cooled by this temperature regulation (cooling) plate.

[0043] Second Embodiment Next, a second embodiment of the present invention will be described. In this second embodiment, components identical to those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted. In the vehicle-mounted battery cooling structure (battery cooling structure) 1 of the first embodiment described above, as shown in FIG. 2 , the underfloor lower section (undercover) 10 located below the battery 2 is horizontally disposed from the front to the rear of the vehicle A. As a result, in the battery cooling structure 1 described above, the cross-sectional area of ​​the second air passage 12 is the same or approximately the same from the front to the rear of the vehicle A. In the second air passage 12, the flow rate (air volume) of the cooling exhaust air drawn in from the cooling air passage 13 increases toward the rear. Therefore, in the battery cooling structure 1 described above, the pressure in the second air passage 12 increases toward the rear.

[0044] In contrast, in the in-vehicle battery cooling structure (battery cooling structure) 1A of the second embodiment, as shown in Fig. 4, the underfloor lower section (undercover) 10A located below the battery 2 is configured to slope downward from the front to the rear of the vehicle A. In this manner, in the battery cooling structure 1A of the second embodiment, the cross-sectional area of ​​the second air passage 12A gradually increases from the front to the rear of the vehicle A, so that the pressure in the second air passage 12A is kept constant or approximately constant from the front to the rear. As a result, the negative pressure suction force of the multiple negative pressure suction sections 14 provided in the second air passage 12A, which draws cooling air (travel air) from the first air passage 11 to the cooling air passage 13, becomes equal from the front to the rear of the second air passage 12A.

[0045] The battery cooling structure 1A of the second embodiment can achieve the same effect as the battery cooling structure 1 of the first embodiment. That is, with the battery cooling structure 1A, each of the multiple battery packs 22 included in the battery 2 is sufficiently cooled by the cooling air (traveling air) drawn directly into the cooling air passage 13 from the first air passage 11, regardless of its position in the vehicle longitudinal direction, such as the front, center, or rear. In addition, with the battery cooling structure 1A, by providing the second air passage 12A having such a shape, the cooling effect (cooling capacity) of the cooling air due to the negative pressure suction action of the negative pressure suction portion 14 on the battery cells 22b of the front, center, and rear battery packs 22 can be more uniformly cooled, thereby more evenly cooling the front, center, and rear battery packs 22.

[0046] The underfloor lower portion (undercover) 10A located below the battery 2 may be configured to slope downward in a stepwise manner rather than inclined downward from the front to the rear of the vehicle A. As a result, the second air passage 12A may be configured (not shown) so that its cross-sectional area increases stepwise from the front to the rear of the vehicle A. The battery cooling structure 1A can obtain the effects described above in the second embodiment even when the second air passage 12A has such a stepwise increasing shape.

[0047] Third Embodiment Next, a third embodiment of the present invention will be described. In this third embodiment, the same components as those in the first and second embodiments are assigned the same reference numerals, and description thereof will be omitted. The cooling structure for an in-vehicle battery (battery cooling structure) 1B of the third embodiment includes a second air passage 12B having an underfloor lower portion (undercover) 10B shown in FIG. 5. The underfloor lower portion 10B of the second air passage 12B slopes downward from the front to the rear of the vehicle A, and its downstream end (rear end) 10B-1 has a funnel shape that curves downward.

[0048] The air flowing toward the rear of the vehicle within the second air passage 12B equipped with the underfloor lower portion 10B of this configuration (the running air taken in from the front side and the cooling exhaust air drawn in from the cooling air passage 13) flows smoothly without encountering resistance at the downstream end 10B-1 and is released to the outside of the vehicle A when it is released (exhausted) to the outside from the downstream end 10B-1.

[0049] According to the battery cooling structure 1B of the third embodiment, the cross-sectional area of ​​the second air passage 12B gradually increases from the front side to the rear side of the vehicle A, thereby achieving the same effect as the battery cooling structure 1A described above. Additionally, according to the battery cooling structure 1B, although many types of air flow through the second air passage 12B, such as the running air taken in from the front side of the vehicle A and the cooling exhaust air drawn in from the cooling air passage 13, the air is smoothly discharged to the outside from the downstream end 10B-1 of the funnel shape. This suppresses a decrease in flow velocity and wind pressure within the second air passage 12B.

[0050] As a result, in the battery cooling structure 1B of the third embodiment, the negative pressure suction force (the suction force that draws the cooling air (traveling air) from the first air passage 11 to the cooling air passage 13) in the negative pressure suction portion 14 is increased. That is, according to the battery cooling structure 1B, the cooling effect (cooling capacity) of the cooling air on the battery cells 22b due to the negative pressure suction action of the negative pressure suction portion 14 can be further increased.

[0051] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. In the battery cooling structure 1A of the second embodiment and the battery cooling structure 1B of the third embodiment described above, the cross-sectional area of ​​the second air passages 12A, 12B gradually increases from the front side to the rear side of the vehicle A, thereby keeping the pressure in the second air passages 12A, 12B constant or approximately constant from the front side to the rear side. In contrast, the battery cooling structure 1C of the fourth embodiment is provided with a second air passage 12C having an underfloor lower portion (undercover) 10C shown in Figure 6, thereby suppressing a pressure increase in the second air passage 12C.

[0052] As shown in FIG. 6 , in the battery cooling structure 1C of the fourth embodiment, the underfloor lower section 10C of the second air passage 12C is horizontal in the front-to-rear and left-to-right directions, similar to the underfloor lower section (undercover) 10 of the first embodiment. However, the second air passage 12C of the battery cooling structure 1C has pressure relief holes 10C-1 in the underfloor lower section 10C as outlets for discharging a portion of the air downstream (slightly rearward) of the three negative pressure suction sections 14 from the front side. Air, such as cooling exhaust air, drawn into the second air passage 12C from the cooling air passage 13 by the negative pressure suction section 14 is quickly discharged to the outside from the second air passage 12C through the pressure relief holes 10C-1. Therefore, the battery cooling structure 1C of the fourth embodiment can achieve the same effects as the battery cooling structure 1 of the first embodiment described above, while suppressing pressure increases in the second air passage 12C due to air, such as cooling exhaust air, drawn into the second air passage 12C.

[0053] 7, a pressure relief valve 10C-3 may be formed by further attaching an opening / closing door 10C-2 to the pressure relief hole 10C-1. The opening / closing door 10C-2 rotates around a rotating shaft 10C-21 having a spring or the like, and can be changed between a closed state (FIG. 7(a)) in which the pressure relief hole 10C-1 is closed and an open state (FIG. 7(b)) in which the pressure relief hole 10C-1 is opened.

[0054] For example, when the pressure in second air passage 12C increases due to the introduction of cooling exhaust air from cooling air passage 13 into second air passage 12C, opening / closing door 10C-2 of pressure release valve 10C-3 may be set to the open state, and at other times opening / closing door 10C-2 of pressure release valve 10C-3 may be set to the closed state. In addition to the above-described effects of the example shown in Fig. 6, battery cooling structure 1C provided with this pressure release valve 10C-3 can prevent problems such as foreign matter or the like entering second air passage 12C from the outside and narrowing the flow path of second air passage 12.

[0055] Fifth Embodiment Next, a fifth embodiment of the present invention will be described. The second air passage 12, 12A-12C provided in the battery cooling structures 1, 1A-1C of the first to fourth embodiments described above is configured with only one air passage through which traveling air introduced from the front of the vehicle A flows. In contrast, the battery cooling structure 1D of the fifth embodiment is provided with a second air passage 12D consisting of multiple air passages (two second air passages 12D-1, two second air passages 12D-2, two second air passages 12D-3, and one second air passage 12D-4) as shown in FIG. 8 instead of the second air passage 12, 12A-12C described above. The lower underfloor portion (undercover) 10D of the battery cooling structure 1D shown in FIG. 9 is formed to form such a second air passage 12D.

[0056] The two second air passages 12D-1, the two second air passages 12D-2, the two second air passages 12D-3, and the one second air passage 12D-4 are provided to correspond to the cooling air passages 13 (cooling air passages 13-1 to 13-4 in FIG. 8) arranged in multiple rows in the front-to-rear direction of the vehicle. That is, the cooling air flowing through the cooling air passages 13 provided in the battery cooling structure 1D is introduced into each of the second air passages 12D as cooled exhaust air.

[0057] The plurality of second air passages 12D provided in the battery cooling structure 1D extend in the rearward direction of the vehicle from the front side of the vehicle A to near the outlets of the corresponding individual cooling air passages 13. Specifically, as shown in Figures 8 and 9, of the plurality of second air passages 12D provided in the battery cooling structure 1D, two second air passages 12D-1 extend from the front side of the vehicle A to an outlet position p1 near the cooling air passage 13-1 between the junction box (JB) 21 and the front-side battery pack 22. Traveling air is introduced into these two second air passages 12D-1 from the front side of the vehicle A, and cooling exhaust air from the cooling air passage 13-1 is drawn in via the negative pressure suction unit 14. These two second air passages 12D-1 quickly discharge the running air introduced from the front side of vehicle A and the cooling exhaust air drawn in from cooling air passage 13-1 via negative pressure suction section 14 to the outside of vehicle A from an outlet (not shown) located at outlet position p1, as shown by the arrows in Figures 8 and 9.

[0058] Furthermore, of the multiple second air passages 12D included in the battery cooling structure 1D, two second air passages 12D-2 extend from the front side of the vehicle A to an outlet position p2 near the cooling air passage 13-2 between the front battery pack 22 and the central battery pack 22. These two second air passages 12D-2 receive airflow caused by vehicle travel from the front side of the vehicle A, and also receive cooling exhaust airflow from the cooling air passage 13-2 via the negative pressure suction section 14. These two second air passages 12D-2 quickly discharge the airflow caused by vehicle travel introduced from the front side of the vehicle A and the cooling exhaust airflow drawn from the cooling air passage 13-2 via the negative pressure suction section 14 to the outside of the vehicle A from outlets (not shown) located at the outlet positions p2, as indicated by the arrows in FIGS. 8 and 9 .

[0059] Furthermore, of the multiple second air passages 12D included in the battery cooling structure 1D, two second air passages 12D-3 extend from the front side of the vehicle A to an outlet position p3 near the cooling air passage 13-3 between the central battery pack 22 and the rear battery pack 22. These two second air passages 12D-3 receive airflow from the front side of the vehicle A, and cool exhaust air from the cooling air passage 13-3 is drawn in via the negative pressure suction section 14. These two second air passages 12D-3 quickly discharge the airflow introduced from the front side of the vehicle A and the cool exhaust air drawn in from the cooling air passage 13-3 via the negative pressure suction section 14 to the outside of the vehicle A from outlets (not shown) located at the outlet positions p3, as indicated by the arrows in FIGS. 8 and 9 .

[0060] Furthermore, one second air passage 12D-4 of the multiple second air passages 12D included in the battery cooling structure 1D extends from the front side of the vehicle A to an outlet position p4 near the cooling air passage 13-4 located on the rear face side of the rear battery pack 22. This one second air passage 12D-4 introduces the running air from the front side of the vehicle A, and also draws in the cooling exhaust air from the cooling air passage 13-4 via the negative pressure suction section 14. This one second air passage 12D-4 quickly discharges the running air introduced from the front side of the vehicle A and the cooling exhaust air drawn in from the cooling air passage 13-4 via the negative pressure suction section 14 to the outside of the vehicle A from an outlet (not shown) located at the outlet position p4, as shown in FIGS.

[0061] According to the battery cooling structure 1D of the fifth embodiment, when the cooling exhaust air is drawn into each of the second air passages 12D corresponding to the plurality of cooling air passages 13, the cooling exhaust air is quickly discharged from the outlet together with the running air introduced from the front side of each of the second air passages 12D, so that no increase in pressure due to the cooling exhaust air occurs in each of the second air passages 12D. Therefore, according to the battery cooling structure 1D, the negative pressure suction force of the plurality of negative pressure suction sections 14 provided in each of the second air passages 12D that draws the cooling air (running air) from the first air passages 11 to the cooling air passages 13 is equal from the front side to the rear side of the second air passage 12D.

[0062] The battery cooling structure 1D of the fifth embodiment as described above can provide the same effects as the battery cooling structure 1 of the first embodiment. In addition, the battery cooling structure 1D can more uniformly cool the battery cells 22b of the front, center, and rear battery packs 22 with the cooling air caused by the negative pressure suction action of the negative pressure suction portion 14, thereby more uniformly cooling the front, center, and rear battery packs 22.

[0063] Although the first to fifth embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention. Furthermore, the above examples can be combined by utilizing each other's technologies as long as there are no particular contradictions or problems in their purposes, configurations, etc.

[0064] 1, 1A, 1B, 1C, 1D: battery cooling structure, 2: battery, 3: vehicle body, 4: floor panel, 5: seat, 6: handle, 7: front portion, 8: front grill opening, 9: upper underfloor, 9a: protrusion, 10, 10A, 10B, 10C, 10D: lower underfloor (undercover), 10B-1: downstream end, 10C-1: pressure relief hole, 10C-2: opening / closing door, 10C-21: rotating shaft, 10C-3: pressure relief valve, 11: first air duct, 12, 12A, 12B, 12C, 12D, 12D-1, 12D -2, 12D-3, 12D-4: second air passage, 13, 13-1, 13-2, 13-3, 13-4: cooling air passage, 14: negative pressure suction section, 21: junction box (JB), 21a: junction box (JB) case, 21b: junction box (JB) body, 22: battery pack, 22a: battery case, 22b: battery cell, 22c, 22d: fixing member, 31: beam member, 31a: space, 32: heat conductive material, A: vehicle, p1, p2, p3, p4: outlet position

Claims

1. A cooling structure for an in-vehicle battery, the battery having a plurality of battery packs arranged along the longitudinal direction of the vehicle, a first air passage formed above the plurality of battery packs through which travelling wind introduced from the front of the vehicle flows as cooling air, a second air passage formed below the plurality of battery packs through which travelling wind introduced from the front of the vehicle flows, a cooling air passage formed in the gaps between the plurality of battery packs through which the cooling air introduced from the first air passage flows, and a negative pressure suction section formed in the second air passage that draws air into the cooling air passage by a negative pressure suction effect generated by the flow speed of the travelling wind.

2. The cooling structure for an in-vehicle battery according to claim 1, wherein the cooling air passages are arranged in multiple rows in the longitudinal direction of the vehicle, and the cooling air flowing through the multiple cooling air passages is introduced into the common second air passage.

3. The cooling structure for an in-vehicle battery according to claim 2, wherein the cross-sectional area of ​​the second air passage increases gradually or in stages toward the rear of the vehicle.

4. The cooling structure for an in-vehicle battery according to claim 2, wherein the second air passage has an outlet for discharging a portion of the air downstream of the negative pressure suction section.

5. The cooling structure for an in-vehicle battery according to claim 1, wherein the cooling air passages are arranged in multiple rows in the longitudinal direction of the vehicle, and the cooling air flowing through the cooling air passages is introduced into the individual second air passages.

6. The cooling structure for an in-vehicle battery according to claim 1, wherein the second air passage has a downstream end that is funnel-shaped.

7. The cooling structure for an in-vehicle battery according to claim 1, wherein the cooling air passage is made of a heat-conductive material and has a plurality of spaces penetrating vertically.

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