Battery pack cooling structure for a motor vehicle

Abstract

A battery pack cooling structure for a motor vehicle, the motor vehicle having a rear seat (1) within a vehicle cabin and a battery pack (7) behind the rear seat, the rear seat (1) being arranged on an upper surface of a rear floor panel (5), the battery pack cooling structure comprising: an air intake line (13) arranged in front of the battery pack (7) and having at least two air inlet openings (14) opening at different positions in the vehicle cabin to admit air located within the vehicle cabin into the battery pack (7) to cool battery modules (8) within the battery pack (7), characterized in that the air intake duct (13) is arranged between the upper surface of the rear floor panel (5) and the rear seat (1); the air intake line (13) comprises an outlet-side air intake line section (11) which communicates with the interior of the battery pack (7); the air intake duct (13) comprises an inlet-side air intake duct section (12) which is connected to said outlet-side air intake duct section (11) at a vehicle front end section of said outlet-side air intake duct section; the two air inlet openings (14) are open to the vehicle cabin at two separate locations in a vehicle width direction, so that the two air inlet openings (14) can receive a part of the cabin air near one lateral side of the vehicle cabin therefrom and can receive another part of the cabin air near the other lateral side of the vehicle cabin; and the inlet-side air intake duct section (12) extends under the rear seat (1) to provide a passage of cabin air from one of the two air inlet openings (14) to the outlet-side air intake duct section (11) and another passage of cabin air from the other of the two air inlet openings (14) to the outlet-side air intake duct section (11).

Description

CROSS REFERENCE TO RELATED APPLICATIONThe present application claims the benefit of priority to Japanese Patent Application No. 2012-260110 filed on Nov. 28, 2012, the entire contents of which are hereby incorporated by reference in their entirety.FIELD OF THE INVENTIONThe present invention relates to a cooling structure of a battery pack for an automobile suitable for cooling the battery pack accommodating high voltage battery modules used particularly in an electric automobile, a hybrid automobile, and the like.GENERAL STATE OF THE ARTIn the battery pack used in an electric automobile or a hybrid automobile, a capacity of the battery pack is also large due to the large electric capacity of battery modules. For this reason, the battery pack is often disposed on an upper surface of a rear floor panel in a vehicle rear side of a rear seat. In such a battery pack that houses high voltage battery modules, heat is generated from the battery modules at a time of charging or discharging. In order to prevent the performance deterioration of the battery modules, there is a need to remove this heat appropriately. As a cooling structure of such a battery pack for an automobile, there is, for example, one described in Japanese Patent Application Publication No. 2006-335244. In this cooling structure of the battery pack for the automobile, an air intake duct for cooling by supplying air, which is inside a vehicle cabin, into the battery pack is disposed at a space between the rear seat and a rear right door, and an air intake opening of the air intake duct is disposed at a side lower than a seat surface of a seat cushion of the rear seat. The inside of the battery pack is connected to a blower, and the battery modules are cooled by drawing the air inside the vehicle cabin into the battery pack by this blower.However, in the battery pack cooling structure for the automobile described in Japanese Patent Application Publication No. 2006-335244, the air intake duct is disposed between the rear seat and the rear right door, and the air intake port is opened at a lower right side of the rear seat. For this reason, when there is one-sidedness in the temperature inside the vehicle cabin and the temperature inside the vehicle cabin is higher on a side where the air intake port of the air intake pipe opens due to, for example, sunlight and the like, there arises a problem that the cooling performance of the inside of the battery pack is lowered.US 2008 / 0 062 622 A1 discloses the arrangement of a battery behind a rear seat for a motor vehicle, wherein the air supply for cooling the battery takes place from the vehicle interior. An air passage for supplying air for cooling the battery is disposed below the seat surface of the rear seat.JP 2008-44 424 A discloses a battery cooling structure in which the supply of cooling air takes place from two different sides. An air duct provided for each of these is provided with a blower in order to be able to selectively draw in air and supply it to the battery for cooling.Further battery cooling devices for a vehicle are known from DE 10 2010 061 774 A1 and DE 11 2008 001 570 T5. In the battery cooling device of DE 10 2010 061 774 A1, cooling air flows through a battery and a PE device, comprising an inverter and a converter, in parallel.In DE 11 2008 001 570 T5, the battery is located in a luggage compartment of the vehicle which is separated from the passenger compartment by a separating wall. Air is drawn from the passenger compartment via a hole in the partition wall and used for cooling the battery, wherein the partition wall has a further exhaust air hole for discharging air in the luggage compartment to the passenger compartment.SUMMARY OF THE INVENTIONThe present invention has been achieved in view of the problem as stated above, and has an object to provide a battery pack cooling structure for an automobile capable of improving cooling performance of an interior of a battery pack.In order to solve the above-mentioned problem, one form of the invention is a battery pack cooling structure for an automobile that cools a battery pack disposed on an upper surface of a rear floor panel at a vehicle rear side of a rear seat and in which battery modules are accommodated, the battery pack cooling structure for the automobile comprising: an output-side air intake duct portion disposed toward a vehicle front side from the battery pack between the upper surface of the rear floor panel and a seat cushion of the rear seat; an input-side air intake duct portion connected at a vehicle front end portion of the output-side air intake duct portion to this output-side air intake duct portion and disposed along a length toward a vehicle width direction between the upper surface of the rear floor panel and the seat cushion of the rear seat; and air inlet openings for admitting air inside the vehicle cabin formed at both vehicle width direction end portions of the input-side air intake duct portion.In addition, a connection portion for the input-side air intake duct portion and the output-side air intake duct portion is disposed at a central portion in the vehicle width direction of the input-side air intake duct portion.According to one form of the invention, at a time of cooling a battery pack disposed on an upper surface of a rear floor panel at a vehicle rear side of a rear seat and housed in the battery module, an output side air intake duct portion connected to the battery pack is disposed toward a vehicle front side between the upper surface of the rear floor panel and a seat cushion of the rear seat, while an input side air intake duct portion connected to the output side air intake duct portion at a vehicle front end portion of the output side air intake duct portion is disposed along a length toward a vehicle width direction between the upper surface of the rear floor panel and the seat cushion of the rear seat, and air intake openings for intake air inside the vehicle cabin are formed at both end portions in the vehicle width direction of the input side air intake duct portion. The increase in temperature of the air inside the vehicle cabin causes a difference in the vehicle width direction due to, for example, direction of the sunlight or condition of the sunlight. To cope with this, the air inside the vehicle cabin is simultaneously sucked from the air suction ports formed at both end portions in the vehicle width direction of the input-side air suction duct portion at a lower side of the seat cushion of the rear seat. For this reason, the air is sucked at both end portions in the vehicle width direction inside the vehicle cabin and is joined at the output side air suction duct portion without the air suction ports being obstructed by the legs of passengers and the like. Accordingly, even if a temperature difference is caused in the air in the vehicle width direction inside the vehicle cabin due to the direction of the sunlight or the nature of the sunlight, the air joined at the output-side air intake duct portion will have a temperature corresponding to the average. Namely, it is possible to improve the cooling performance of the interior of the battery pack by preventing air having an excessive temperature rise from being drawn into the interior of the battery pack.In addition, a connection portion for the input-side air intake duct portion and the output-side air intake duct portion is disposed at a central portion in the vehicle width direction of the input-side air intake duct portion. For this reason, even if a temperature difference is caused in the air on the both sides in the vehicle width direction inside the vehicle cabin, the air having a temperature rise and the air having a lower temperature can be mixed uniformly with the same amount of each, so that it is possible to securely prevent air having an excessive temperature rise from being drawn into the inside of the battery pack.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a perspective view showing an embodiment of a battery pack cooling structure for an automobile of the present invention. FIG. 2 is a top view of the battery pack cooling structure for the motor vehicle of FIG. 1. FIG. 3 is a side view of the battery pack cooling structure for the motor vehicle of FIG. 1. FIG. 4 is a front view of the battery pack cooling structure for the motor vehicle of FIG. 1. FIG. 5 is a perspective view of an air intake duct of the battery pack cooling structure for the motor vehicle of FIG. 1. FIG. 6 is a perspective view of an air intake duct showing a modified example of the battery pack cooling structure for the automobile of FIG. 1. FIG. 7 is a side view of the battery pack cooling structure for the motor vehicle of FIG. 6.DETAILED DESCRIPTION OF THE INVENTIONNext, the embodiments of the battery pack cooling structure for the automobile of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the present embodiment of the battery pack cooling structure for the automobile, FIG. 2 is a plan view of the battery pack cooling structure for the automobile of FIG. 1, FIG. 3 is a side view of the battery pack cooling structure for the automobile of FIG. 1, FIG. 4 is a front view of the battery pack cooling structure for the automobile of FIG. 1, and FIG. 5 is a perspective view of an air intake duct of the battery pack cooling structure for the automobile of FIG. 1. the automobile of the present invention is an electric automobile or a hybrid automobile equipped with seating in two rows front and rear, i.e., rows of seats. A rear seat 1 corresponding to a rear row is configured to be equipped with a seat cushion 2 on which passengers will be seated and a seat back 3 to be a backrest for passengers. The rear seat 1 shown in FIGS. 1 to 4 has a length in a vehicle width direction such that two or three passengers can be seated.A vehicle front side from the seat back 3 of the rear seat 1 is a vehicle cabin, and a vehicle rear side from the seat back 3 of the rear seat 1 is a trunk room. On a lower surface of the vehicle cabin, a floor surface is formed by a front floor panel 4, and on a lower surface of the trunk room, a floor surface (floor surface) is formed by a rear floor panel 5. The front floor panel 4 and the rear floor panel 5 of the present embodiment are laid one behind the other, and a level difference portion 6 at which the rear floor panel 5 becomes higher is formed at a connecting portion of the two, and the seat cushion 2 of the rear seat 1 is disposed on this level difference portion 6. In the present embodiment, a battery pack 7 is disposed on an upper surface of the rear floor panel 5 at a vehicle rear side of the rear seat 1. Within this battery pack 7, a plurality of battery modules 8 constituted by a plurality of cells are accommodated, the electric power is collected in each of the battery modules 8, and the collected electric power is also discharged. Note that in FIG. 5, the battery pack is omitted. In addition, there are cases in the trunk room where the rear floor panel 5 is covered by a cargo screen.The interior of the battery pack 7 is connected to a cooling fan 10 via a drain duct 9 disposed to project toward the vehicle rear side. When the cooling fan 10 is activated, the air inside the vehicle cabin is drawn from an air intake passage to be described below, and it is possible to cool the battery modules 8 inside the battery pack 7. On the other hand, at a central portion in the vehicle width direction of the battery pack 7, an output side air intake duct portion 11 is connected in communication with the interior of the battery pack 7. This downstream air intake duct portion 11 is disposed along a length toward the vehicle front side between the seat cushion 2 of the rear seat 1 and the rear floor panel 5. Then, to an end portion on the vehicle front side of the output side air intake duct portion 11, there is connected an input side air intake duct portion 12 having a length in a direction intersecting with a length direction of this output side air intake duct portion 11, that is, the vehicle width direction, and an air intake duct 13 for cooling the battery pack 7 is formed by this input side air intake duct portion 12 and the output side air intake duct portion 11. The intake-side air intake duct portion 12 and the exhaust-side air intake duct portion 11 constituting this air intake duct 13 are respectively accommodated within concave grooves formed on a lower surface of the seat cushion 2 of the rear seat 1. In addition, specifically, the input-side air intake duct portion 12 functions as a cross member below the seat cushion 2 of the rear seat 1, so that the air intake duct 13 as a whole also functions as a reinforcing member for the seat cushion 2 of the rear seat 1.In the present embodiment, at both end portions of the input-side air intake duct portion 12 having a length in the vehicle width direction, air intake ports 14 for intake of the air inside the vehicle cabin are provided by being opened. These air inlet ports 14 open near the left and right rear doors in the vehicle cabin, i.e., at both end portions in the vehicle width direction of the vehicle cabin, on a lower side of the seat cushion 2 of the rear seat 1, and from there, let the air inside the vehicle cabin enter and suck it into the inside of the battery pack 7. In addition, a connection portion for the output-side air intake duct portion 11 and the input-side air intake duct portion 12 is configured to be disposed at a central portion in the vehicle width direction of the input-side air intake duct portion 12 having a length in the vehicle width direction. For this reason, as seen in FIG. 2, a distance L 1 in the vehicle width direction from the output-side air intake duct portion 11 to the air intake opening 14 on the right vehicle side and a distance L 2 in the vehicle width direction from the output-side air intake duct portion 11 to the air intake opening 14 on the left vehicle side are equal to or approximately equal to each other.Within the vehicle cabin of the motor vehicle, as is well known, one-way occurs at the temperature of the air due to the direction of the sunlight and the nature of the sunlight. This one-side property at the temperature of the air inside the vehicle cabin is generated in most of the vehicle front-rear direction and the vehicle width direction depending on whether the sunlight appears or not and the like. For example, at a time of intake of the air for cooling the inside of the battery pack from inside the vehicle cabin, in the case of opening the air intake port only on one side in the vehicle width direction, there is a possibility of intake of the air having a temperature excessively increased by the sunlight, and in such a case, the cooling performance of the inside of the battery pack 7 will be lowered. In contrast, in the battery pack cooling structure for the automobile of the present invention, the air for cooling the inside of the battery pack 7 is taken in from both sides in the vehicle width direction inside the vehicle cabin, at a lower side of the seat cushion 2 of the rear seat 1. For this reason, even in the case that the temperature of the air inside the vehicle cabin is higher on one side in the vehicle width direction, by letting the air inside the vehicle cabin be lower in temperature on another side in the vehicle width direction, it is possible to prevent the air having an excessively high temperature from being sucked from the output-side air suction pipe portion 11 to the inside of the battery pack 7. Further, by setting the distance L 1 from the output-side air intake duct portion 11 to the air intake port 14 on the right vehicle side and the distance L 2 from the output-side air intake duct portion 11 to the air intake port 14 on the left vehicle side in the same manner, the air inside the vehicle cabin having an increased temperature on one side in the vehicle width direction and the air inside the vehicle cabin having a lower temperature on another side in the vehicle width direction can be mixed smoothly.Therefore, in the battery pack cooling structure for the automobile according to the present embodiment, at a time of cooling a battery pack 7 disposed on an upper surface of a rear floor panel 5 at a vehicle rear side of a rear seat 1 and accommodated in the battery module 8, the output-side air intake duct portion 11 connected to the battery pack 7 is disposed toward the vehicle front side between the upper surface of the rear floor panel 5 and the seat cushion 2 of the rear seat 1, while the input-side air intake duct portion 12 connected to the vehicle front end portion of the output-side air intake duct portion 11 is disposed along a length toward the vehicle width direction between the upper surface of the rear floor panel 5 and the seat cushion 2 of the rear seat 1, and the air inlet openings 14 for introducing the air inside the vehicle cabin are formed at the both end portions in the vehicle width direction of the input-side air intake duct portion 12. The increase in temperature of the air inside the vehicle cabin causes a difference in the vehicle width direction due to, for example, a direction of the sunlight or a condition of the sunlight. To cope with this, the air inside the vehicle cabin is simultaneously sucked from the air suction ports 14 formed at both end portions in the vehicle width direction of the input-side air suction duct portion 12 at a lower side of the seat cushion 2 of the rear seat 1. For this reason, the air is sucked at both end portions in the vehicle width direction inside the vehicle cabin and is joined at the output side air suction duct portion 11 without the air suction ports being obstructed by the legs of passengers and the like. Accordingly, even if a temperature difference in the vehicle width direction is caused inside the vehicle cabin, the air joined at the output side air intake duct portion 11 will have a temperature corresponding to the average. Namely, it is possible to improve the cooling performance of the interior of the battery pack 7 by preventing air having an excessive temperature rise from being drawn into the interior of the battery pack 7.In addition, the connection portion for the input-side air intake duct portion 12 and the output-side air intake duct portion 11 is disposed at a central portion in the vehicle width direction of the input-side air intake duct portion 12. For this reason, even if a temperature difference is caused in the air on the both sides in the vehicle width direction inside the vehicle cabin, the air having a temperature rise and the air having a lower temperature can be mixed uniformly with the same amount of each, so that it is possible to securely prevent air having an excessive temperature rise from being drawn into the inside of the battery pack 7.FIGS. 6 and 7 are a modified example of the battery pack cooling structure for the automobile of the present embodiment, in which FIG. 6 is a perspective view of the air intake duct 13 and FIG. 7 is a perspective view of the air intake duct 13. Note that configurations similar to the above-described embodiment are given similar reference numerals, and their detailed description is omitted. In this modified example, the output-side air intake duct portion 11 is bored into the input-side air intake duct portion 12 and further expanded to the vehicle front side (an end portion on the vehicle front side of the seat cushion 2 of the rear seat 1), and a central air intake opening 15 opening to the vehicle front side is formed at this expanded end portion on the vehicle front side. The output-side air intake duct portion 11 and the input-side air intake duct portion 12 have their insides connected to each other at a piercing portion. According to this modified example, in addition to the above-described embodiment, the air inside the vehicle cabin at the central portion in the vehicle width direction can also be taken in and mixed as the air for cooling the inside of the battery pack 7, so that it becomes possible to further uniformize the temperature of the air for cooling the inside of the battery pack 7.

Claims

A battery pack cooling structure for an automobile, the automobile having a rear seat (1) inside a vehicle cabin and a battery pack (7) behind the rear seat, the rear seat (1) being disposed on an upper surface of a rear floor panel (5), the battery pack cooling structure comprising: an air intake duct (13) disposed in front of the battery pack (7) and having at least two air intake ports (14) opening in the vehicle cabin at different positions to introduce air inside the vehicle cabin into the battery pack (7) to cool battery modules (8) inside the battery pack (7), characterized in that the air intake duct (13) is disposed between the upper surface of the rear floor panel (5) and the rear seat (1); the air intake duct (13) comprises an output side air intake duct portion (11) communicating with the inside of the battery pack (7); the air intake duct (13) includes an input-side air intake duct portion (12) connected to this output-side air intake duct portion (11) at a vehicle front end portion of the output-side air intake duct portion (11); the two air intake ports (14) are open to the vehicle cabin at two locations separated from each other in a vehicle width direction, so that the two air intake ports (14) can receive a part of the cabin air near one lateral side of the vehicle cabin thereof and can receive another part of the cabin air near the other lateral side of the vehicle cabin; and the intake-side air duct portion (12) extends under the rear seat (1) to provide a passage of cabin air from the one of the two air inlet openings (14) to the intake-side air duct portion (11) and another passage of cabin air from the other of the two air inlet openings (14) to the intake-side air duct portion (11).The battery pack cooling structure for an automobile according to claim 1, characterized in that a connection portion at which the input-side air intake duct portion (12) is connected to the output-side air intake duct portion (11) is disposed at a central portion in the vehicle width direction of the input-side air intake duct portion (12).The battery pack cooling structure for an automobile according to claim 1, characterized in that a distance in the vehicle width direction from the output-side air intake duct portion (11) to one of the air intake ports (14) on the right vehicle side and a distance in the vehicle width direction from the output-side air intake duct portion (11) to another one of the two air intake ports (14) on the left vehicle side are set to be equal.The battery pack cooling structure for an automobile according to claim 1, characterized in that the output-side air intake duct portion (11) uniformly mixes the cabin air from one of the two air intake ports (14) and the cabin air from the other of the two air intake ports (14).The battery pack cooling structure for an automobile according to claim 1, characterized by further comprising a central air inlet port (15) open to the vehicle cabin at a location between one and the other of the two air inlet ports (14).

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