CN114342162A

CN114342162A - Battery box for electric vehicle

Info

Publication number: CN114342162A
Application number: CN202080063611.4A
Authority: CN
Inventors: 桥村彻; 山川大贵
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2019-09-10
Filing date: 2020-07-29
Publication date: 2022-04-12
Also published as: JP2021041783A; WO2021049193A1; JP7194094B2

Abstract

A battery box (100) for an electric vehicle is provided with: the battery pack is provided with a bathtub-shaped tray (120) having a concave-shaped containing part (122) for containing a battery (30), a frame (110) which is arranged around the whole periphery of the tray (120) in a plan view and is connected with the tray (120), a top cover (130) which is arranged above the tray (120) and closes the containing part (122), and a bottom cover (140) which is arranged below the tray (120).

Description

Battery box for electric vehicle

Technical Field

The present invention relates to a battery box for an electric vehicle.

Background

An electric vehicle such as an electric automobile needs to mount a large-capacity battery in order to secure a sufficient cruising distance, and a large vehicle interior is required. In order to satisfy these requirements at the same time, in many electric vehicles, a large-capacity battery is housed in a battery box and mounted on the entire underfloor surface of the vehicle. Therefore, the battery box for the electric vehicle is required to have high sealability for preventing the electronic components from being defective by preventing the entry of water from the road surface or the like, and to have high impact strength for protecting the battery inside.

For example, patent document 1 discloses a battery case in which sealing performance is improved by using a tray formed by cold rolling and press forming a metal plate into a bathtub shape. Patent document 2 discloses a battery case in which a bottom plate and a frame of the battery case are joined by a joining means such as welding, thereby improving space efficiency and impact strength.

Patent document

Patent document 1 Japanese patent laid-open publication No. 2017-

Patent document 2, Japanese patent laid-open No. 2012 and 212659.

In the battery case of patent document 1, the frame does not entirely surround the periphery of the battery case, and therefore there is room for improvement in impact strength. Further, since the bathtub-like tray constitutes the lower surface of the vehicle body, there is room for improvement in strength against the upward lifting from the road surface.

In the battery case of patent document 2, since a bathtub-shaped tray is not used, it is necessary to prevent water from entering from a welded joint or the like, and there is room for improvement in sealing performance.

Disclosure of Invention

The invention aims to ensure sufficient sealing performance and strength in a battery box for an electric vehicle.

The present invention provides a battery box for an electric vehicle, comprising: the battery pack includes a bathtub-shaped tray having a concave receiving portion for receiving a battery, a frame arranged to surround the entire periphery of the tray in a plan view and joined to the tray, a top cover arranged above the tray and closing the receiving portion, and a bottom cover arranged below the tray.

According to this configuration, the storage portion is sealed because the storage portion is closed by the tray and the top cover. In particular, since the tray is bathtub-shaped, no seam is provided except for the joint portion between the tray and the top cover. Therefore, high sealing performance can be ensured without welding or the like around the entire circumference with respect to the battery housing portion. Further, since the frame is disposed so as to surround the entire periphery of the tray, high impact strength can be ensured. Further, since the undercover is disposed below the tray, the tray is not exposed on the lower surface of the vehicle body, and high strength can be secured against the upward pushing from the road surface.

The bottom cover may be made of a material different from that of the frame, and may be bonded to the frame by a different material.

With this configuration, the material of the undercover and the frame can be changed according to the application, and the versatility of the battery box for an electric vehicle can be improved. For example, the frame may be made of an aluminum alloy for weight reduction, and the bottom cover may be made of steel for increasing the top strength from the road surface. Here, the dissimilar metal joining means a joining method of different metal materials, and means, for example, bolt joining, rivet joining, easw (element Arc Spot welding), or the like.

The tray may be made of plastic.

According to this configuration, the shape of the tray can be formed arbitrarily, and the weight of the tray can be reduced. In particular, it is preferable that the capacity of the storage portion of the tray is increased and the radius of the ridge portion is reduced in order to store the battery having the largest capacity. In contrast, the tray is made of plastic, so that the tray can be easily molded.

The frame includes an upper cross member extending in the vehicle width direction, and a lower cross member disposed below the upper cross member in the vehicle width direction, and the tray is sandwiched between the upper cross member and the lower cross member in the vehicle height direction.

According to this structure, the strength of the vehicle body against a side impact can be improved by the upper cross member and the lower cross member. Further, the tray is sandwiched by the upper side cross member and the lower side cross member, so that the tray can be stably fixed. Further, since the upper cross member and the lower cross member can be formed of different materials, weight reduction and high impact strength on the side surface of the vehicle body can be easily achieved in accordance with required performance.

The roof cover, the upper cross member, the pallet, and the lower cross member may be provided with concentric holes in plan view, bolts may be inserted into the concentric holes, the bolts may completely penetrate the roof cover, the upper cross member, and the pallet, and the bolts may remain in the vehicle body without completely penetrating the lower cross member, and the roof cover, the upper cross member, the pallet, and the lower cross member may be integrally coupled to the vehicle body.

According to this structure, the roof cover, the upper side cross member, the tray, and the lower side cross member are firmly joined to the vehicle body via bolts. In the battery box, a structure that is firmly fixed to the vehicle body in such a manner that excessive vibration is not applied to the battery is effective. Further, the bolts do not completely penetrate the lower cross member, so that the sealability can be prevented from being damaged.

The vehicle may further include a corrugated panel disposed between the tray and the under cover in the vehicle height direction.

According to this structure, the roof strength can be further improved by the corrugated panel. In particular, the corrugated panel suitably absorbs the impact, and is therefore effective for improving the roof strength.

According to the present invention, sufficient sealing performance and strength can be ensured in the battery case for an electric vehicle.

Drawings

Fig. 1 is a side view of an electric vehicle on which a battery box for an electric vehicle according to an embodiment of the present invention is mounted.

Fig. 2 is a schematic cross-sectional view of the vicinity of the case member of the battery case.

Fig. 3 is an exploded perspective view of the battery case.

Fig. 4 is a perspective view of the battery case.

Fig. 5 is a schematic cross-sectional view of the vicinity of the cross member of the battery box.

Fig. 6 is a schematic cross-sectional view of the vicinity of the cross member of the battery box in the modification.

Description of the reference numerals

1 electric vehicle

10 front part of vehicle body

20 center part of vehicle body

30 cell

31 electric cable

100 Battery box (Battery box for electric vehicle)

110 frame

111 frame body

111a front wall

111b rear wall

111c, 111d side wall

112 crossbeam

112a upper side beam

112b lower side beam

112b1 partition wall

112b2 flange portion

113 inner extension part

113a hole

120 tray

121 flange part

122 housing part

122a bottom

122b extension

123 screw

124 bolt

130 top cover

140 bottom cover

141. 142 element

150 corrugated panel

200 case body parts

300 floor panel

400 ground beam.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Referring to fig. 1, an electric vehicle 1 is a vehicle that runs by driving a motor with electric power supplied from a battery 30. The electric vehicle 1 may be a vehicle that runs by electric power, and may be an electric vehicle, a hybrid vehicle, or the like. The type of vehicle is not particularly limited, and may be a passenger car, a truck, a work vehicle, or other mobile equipment. Hereinafter, a case where the electric vehicle 1 is a passenger car type electric vehicle will be described as an example.

The electric vehicle 1 is equipped with a motor, a high-voltage device, and the like, not shown, in the vehicle body front portion 10. Further, in the electric vehicle 1, a battery box 100 for an electric vehicle (hereinafter, simply referred to as a battery box 100) that houses the battery 30 is mounted on substantially the entire surface under the floor of the vehicle compartment R in the vehicle body center portion 20. In fig. 1, the front-rear direction of the electric vehicle 1 is indicated by the X-direction, and the height direction (vertical direction) is indicated by the Z-direction. The same applies to the following drawings, and fig. 2 and the following drawings show the vehicle width direction by the Y direction.

Referring to fig. 2, battery box 100 is disposed inside case member 200 in the vehicle width direction, and is supported by case member 200. The box member 200 is a framework member extending in the vehicle longitudinal direction in the lower portions of both ends in the vehicle width direction of the electric vehicle 1 (see fig. 1). The case member 200 is formed by joining a plurality of metal plates, and has a function of protecting the vehicle interior R and the battery case 100 from a collision from the side of the electric vehicle 1.

Referring to fig. 3 and 4 together, the battery box 100 includes: a frame 110 defining a through hole TH, a bathtub-shaped tray 120, and a top cover 130 and a bottom cover 140 disposed so as to sandwich them from above and below. In the present embodiment, the battery box 100 preferably further includes a plurality of corrugated panels 150 disposed between the tray 120 and the undercover 140 in the vehicle height direction.

The frame 110 is a frame-shaped member that is a skeleton of the battery case 100, and in the present embodiment, is made of, for example, an aluminum alloy extruded product. Among them, the frame 110 may be composed of an aluminum alloy extruded product, an aluminum alloy cast product, a magnesium alloy extruded product, a magnesium alloy cast product, or a combination of these. The frame 110 includes a rectangular frame-shaped frame body 111 in a plan view, and 4 cross members 112 extending in the vehicle width direction inside the frame body 111.

The cross member 112 includes 4 upper cross members 112a extending in the vehicle width direction, and 4 lower cross members 112b arranged below the upper cross members 112a in the vehicle width direction. The 4 upper side beams 112a are connected by the electric cables 31. The electric cable 31 is connected to the battery 30.

In the present embodiment, the frame 110 having the through holes TH is described as an example, but the shape of the frame 110 is not particularly limited. For example, the frame 110 may have a hollow portion having a concave shape instead of the through hole TH.

The frame body 111 includes:

side walls

111c and 111d extending in the vehicle longitudinal direction, and a front wall 111a and a rear wall 111b connecting these and extending in the vehicle width direction. The

side walls

111c and 111d are substantially L-shaped in cross section perpendicular to the vehicle front-rear direction. The

side walls

111c and 111d are hollow with the inside thereof partitioned into a plurality of compartments. The front wall 111a and the rear wall 111b are rectangular cylinders, and the interiors of the front wall 111a and the rear wall 111b are similarly hollow.

The 4 upper side beams 112a and the 4 lower side beams 112b extend in parallel with the front wall 111a and the rear wall 111b and are arranged at substantially equal intervals.

Referring to fig. 3 and 5, the upper cross member 112a is disposed in the tray 120 and contacts the inner surface of the tray 120 at both ends in the vehicle width direction. The upper cross member 112a is hollow, and has a rectangular closed cross-sectional shape in a cross section perpendicular to the vehicle width direction. For example, the upper side cross member 112a is made of high tensile steel.

The lower cross member 112b is disposed below the upper cross member 112a, and connects the side wall 111c and the side wall 111 d. The lower cross member 112b is hollow, and has a rectangular closed cross-sectional shape in which the interior is partitioned by a partition wall 112b1 in a cross section perpendicular to the vehicle width direction. Further, the lower cross member 112b has a flange portion 112b2 at a lower end for engagement with the bottom cover 140. Flange portion 112b2 extends in a horizontal plane parallel to bottom cover 140. The lower cross member 112b is, for example, an extrusion molded product (aluminum alloy extrusion) made of an aluminum alloy.

The cross member 112 (the upper cross member 112a and the lower cross member 112 b) has a function of improving the strength of the battery case 100. In particular, the strength of the electric vehicle 1 (see fig. 1) against a side impact can be improved by the cross member 112. However, the cross member 112 is not necessarily required, and may be omitted as needed. In addition, even when the cross member 112 is provided, the form thereof is not particularly limited, and the shape, arrangement, number, and the like can be arbitrarily set.

Referring to fig. 3, the tray 120 is a bathtub-shaped member that houses the battery 30, and is made of, for example, plastic. The tray 120 includes a flange portion 121 extending in a horizontal direction (direction X, Y) at an outer edge portion thereof, and a receiving portion 122 continuous with the flange portion 121 and having a concave shape. The receiving portion 122 is a portion that receives the battery 30. A bottom portion 122a of the receiving portion 122 is provided with a protruding portion 122b having a shape complementary to that of the lower cross member 112 b.

Referring to fig. 5, lower cross member 112b is disposed below extension portion 122b, and upper cross member 112a is disposed above extension portion 122 b. That is, the tray 120 is sandwiched by the upper cross member 112a and the lower cross member 112b in the vehicle height direction. In the present embodiment, the upper cross member 112a, the extension portion 122b, and the lower cross member 112b are fastened and fixed together by screws 123. Although not shown in detail, the upper cross member 112a and the top cover 130 are also screwed in the same manner.

Referring to fig. 3 and 4 together, in a state where the tray 120 and the frame 110 are combined, the flange portion 121 of the tray 120 is placed on the upper surface of the frame body 111 of the frame 110, and the receiving portion 122 of the tray 120 is disposed in the frame body 111 of the frame 110. At this time, the protruding portion 122b is arranged to partially cover the lower cross member 112 b.

Referring to fig. 2 and 3, batteries 30 (5 in the present embodiment) are disposed in the receiving portion 122 of the tray 120. The housing portion 122 is closed by the top cover 130 from above the battery 30, and the battery 30 is housed in the battery case 100. In the illustrated example, the top cover 130 and the tray 120 are fastened and fixed to the frame 110 by screws. Above the roof cover 130, a floor panel 300 constituting a floor surface of the vehicle interior R and a floor cross member 400 extending in the vehicle width direction in the vehicle interior R are disposed. Further, a bottom cover 140 is disposed below the tray 120. The undercover 140 is joined to the frame 110 and constitutes the lower surface of the vehicle body.

Preferably, the bottom cover 140 is made of a material different from that of the frame 110. This allows the material of the bottom cover 140 and the frame 110 to be changed according to the application, thereby improving the versatility of the battery case 100. In the present embodiment, the frame 110 is made of, for example, an aluminum alloy as described above, and the undercover 140 is made of, for example, steel. Therefore, the frame 110 can be reduced in weight, and the strength of the bottom cover 140 against the top of the road surface can be increased.

Referring to a partial enlarged view shown by a dotted circle of fig. 2, the bottom cover 140 is joined to the frame 110 by a different material. The dissimilar metal joining means a joining method of dissimilar metal materials, and for example, it means bolt joining, rivet joining, easw (element Arc Spot welding), or the like. In the present embodiment, easw (element Arc Spot welding) is used as the dissimilar material bonding. In the EASW, a steel rivet (element) 141 having a hollow flange is fitted into a hole 113a provided in an inner extension 113 of an aluminum alloy frame 110, placed on a steel bottom cover 140, and a welding material melted by arc welding is cast into a hollow portion in the element 141. That is, the element 141 and the bottom cover 140 are firmly welded by arc welding from a single side. At this time, the frame 110 is clamped between the flange of the member 141 and the bottom cover 140 to be engaged therewith. In this joint portion, a known adhesive or seal may be used to improve the sealing property on the inside (upper side) of the bottom cover 140.

Referring to fig. 5, in the present embodiment, the lower cross member 112b is also joined to the undercover 140 by a different material. Specifically, EASW is used as described above, and the flange portion 112b2 of the lower beam 112b is joined to the undercover 140 using the element 142. In this joint portion, a known adhesive or sealing material may be used to improve the sealing property on the inner side (upper side) of the bottom cover 140.

In the present embodiment, the corrugated panel 150 is disposed between the tray 120 and the undercover 140 in the vehicle height direction. A plurality of corrugated panels 150 (5 in the present embodiment) are provided corresponding to the number of batteries 30 (5 in the present embodiment). The corrugated panel 150 has a corrugated cross section when viewed in the vehicle width direction. The corrugated panel 150 has a function of relaxing the upward impact from the road surface.

According to the battery box 100 as described above, the following operational effects are achieved.

According to the present embodiment, since the receiving portion 122 is closed by the tray 120 and the top cover 130, the receiving portion 122 is sealed. In particular, since the tray 120 has a bathtub shape, no seam is provided except for the joint portion between the tray 120 and the top cover 130. Therefore, high sealing performance can be ensured without welding or the like around the entire circumference with respect to the housing portion 122 of the battery 30. Further, since the frame 110 is disposed so as to surround the entire circumference of the tray 120, high impact strength can be ensured. Further, since the undercover 140 is disposed below the tray 120, the tray 120 is not exposed on the lower surface of the vehicle body, and high strength can be secured against the top of the road surface.

Further, since the tray 120 is made of plastic, the shape of the tray 120 can be arbitrarily formed, and the weight of the tray 120 can be reduced. In particular, in order to accommodate the battery 30 having the largest capacity possible, the receiving portion 122 of the tray 120 is preferably formed to have a larger capacity and a smaller radius of the ridge portion. In contrast, such molding can be easily performed by making the tray 120 of plastic.

Further, since the upper cross member 112a and the lower cross member 112b are provided, the strength of the vehicle body against side impact can be improved as compared with a vehicle body not provided with these members. Further, since the tray 120 is sandwiched between the upper cross member 112a and the lower cross member 112b, the tray can be stably fixed. Further, since the upper cross member 112a and the lower cross member 112b can be formed of different materials, weight reduction and high impact strength from the side can be easily achieved in accordance with required performance. For example, as in the present embodiment, the upper side cross member 112a can be made of high tensile steel to ensure high impact strength on the side surface of the vehicle body, and the lower side cross member 112b can be made of aluminum alloy to reduce the weight.

Further, since the corrugated panel 150 is provided, the strength of the roof from the road surface can be further improved. In particular, the corrugated panel 150 suitably absorbs the impact and is therefore effective for improving the roof strength.

(modification example)

A modification of the present embodiment will be described with reference to fig. 6.

In the modification, bolts 124 for integrally fixing the top cover 130, the upper cross member 112a, the tray 120, and the lower cross member 112b are used instead of the screws 123 (see fig. 5) of the above embodiment. The top cover 130, the upper cross member 112a, the tray 120, and the lower cross member 112b have holes CH concentric in plan view for inserting the bolts 124 in the vertical direction. The concentric hole CH is provided so that the bolt 124 completely penetrates the top cover 130, the upper cross member 112a, and the tray 120. The hole CH is provided only in the upper surface of the lower cross member 112b so that the bolt 124 does not completely penetrate the lower cross member 112b and the bolt 124 penetrates only the upper surface of the lower cross member 112 b.

Further, the bolt 124 is fixed to a vehicle body such as the floor panel 300 at an upper end portion. Therefore, in the present embodiment, the floor panel 300 is also provided with the concentric hole CH. The bolts 124 are inserted through the concentric holes CH from above, and the floor panel 300, the top cover 130, the upper cross member 112a, the tray 120, and the lower cross member 112b are integrally fixed in this order from above, and are fixed at the lower end portions by nuts. The undercover 140 is joined by a different material such as the lower cross member 112b and the EASW as described above.

According to the present modification, the top cover 130, the upper cross member 112a, the tray 120, the lower cross member 112b, and the bottom cover 140 are firmly coupled to the vehicle body such as the floor panel 300 via the bolts 124. In battery case 100, it is effective to have a structure that is firmly coupled to the vehicle body so as not to excessively apply vibration to battery 30.

If the bolts are arranged so as to completely penetrate from the upper surface of the top cover 130 to the lower surface of the bottom cover 140 in the structure of the present modification, the necessary sealing performance may not be ensured. In this modification, the bolt 124 does not pass through the lower cross member 112b completely, but passes through only the upper surface of the lower cross member 112b, and therefore the bolt 124 does not pass through the undercover 140, and necessary sealing performance is ensured on the inner side (upper side) of the undercover 140. In order to further improve the sealing property, a known adhesive or sealing material may be used at the contact portion between the undercover 140 and the frame 110.

While the present invention has been described with reference to the specific embodiments, the present invention is not limited to the embodiments described above, and can be implemented with various modifications within the scope of the present invention.

For example, in the above embodiment, the tray 120 is made of plastic, but the material of the tray 120 is not limited to plastic. The tray 120 may be made of a metal such as steel or aluminum alloy.

Claims

1. A battery box for an electric vehicle is provided with:

a bathtub-shaped tray having a concave storage part for storing a battery,

A frame arranged to surround the entire periphery of the tray in a plan view and joined to the tray,

A top cover disposed above the tray and closing the accommodating portion,

A bottom cover arranged below the tray.

2. The battery box for electric vehicles according to claim 1,

the bottom cover is made of a material different from that of the frame, and is bonded to the frame by a different material.

3. The battery box for electric vehicles according to claim 1 or 2,

the tray is made of plastic.

4. The battery box for electric vehicles according to claim 1 or 2,

the frame includes an upper cross member extending in the vehicle width direction, a lower cross member disposed below the upper cross member in the vehicle width direction,

the tray is sandwiched between the upper cross member and the lower cross member in the vehicle height direction.

5. The battery box for electric vehicles according to claim 4,

the top cover, the upper cross member, the tray, and the lower cross member have holes concentric in a plan view,

a bolt is inserted through the concentric hole,

the bolt passes completely through the top cover, the upper cross member, and the tray and does not pass completely through the lower cross member,

the bolts remain in the vehicle body, so that the roof cover, the upper cross member, the tray, and the lower cross member are integrally joined to the vehicle body.

6. The battery box for electric vehicles according to claim 1 or 2,

the vehicle further includes a corrugated panel disposed between the tray and the under cover in the vehicle height direction.