Battery pack fixing structure

Abstract

To provide a battery pack fixing structure that is advantageous for smoothly fixing the battery pack to the floor panel without increasing the size of the cylindrical member. [Solution] The fixing structure 28 for fixing the battery pack 10 to the floor panel 22 includes a cylindrical member 30 that penetrates vertically from the opening 1404 in the bottom wall 1402 of the tray 14 of the battery pack 10 through the opening 1604 in the upper wall 1602 of the cover 16 of the battery pack 10 to the lower surface of the floor panel 22, a bolt 32 that is inserted inside the cylindrical member 30 and fastens the battery pack 10 to the floor panel 22, and a grommet 34 made of an elastic material that is attached to the upper part of the cylindrical member 30 and connected to the edge of the opening 1604 in the upper wall 1602 of the cover 16.

Description

Technical Field

[0001] The present invention relates to a battery pack fixing structure. Background Art

[0002] Electric vehicles such as electric vehicles and hybrid vehicles that use a motor as a driving source are provided with a battery pack that supplies electric power to the motor. A battery pack includes a plurality of battery modules, an electrical component section for controlling these battery modules, and a case that accommodates these battery modules and the electrical component section, and is disposed below a floor panel of a vehicle. The case is composed of a tray on which the battery module and the electrical component section are placed, and a cover that covers the tray from above. In recent years, battery packs have tended to increase in capacity. For this reason, while securing vehicle interior space by suppressing the vertical dimension of the battery pack, the capacity of the battery pack is often secured by expanding the dimensions in the vehicle longitudinal direction and the vehicle width direction. Therefore, battery packs have been made thinner, and merely fixing both sides of the battery pack in the vehicle width direction to vehicle body frame members raises concerns about adverse effects such as deflection of the battery pack and vibration during traveling. Therefore, as a battery pack fixing structure for fixing a battery pack to a floor panel, there has been disclosed a structure in which a plurality of cylindrical members are provided in the battery pack that penetrate vertically from a through hole in a tray bottom wall of the battery pack, through a through hole in an upper cover wall of the battery pack, to the lower surface of the floor panel, and bolts are inserted into the interiors of these cylindrical members to fasten the battery pack to nuts welded to the floor panel (see Patent Document 1). Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2017-204386 Summary of the Invention Problem to be Solved by the Invention

[0004] By the way, the central axis of the nut welded to the floor panel and the central axis of the through-hole in the upper wall of the battery pack cover do not necessarily coincide due to variations in part precision, resulting in a misalignment. To absorb such misalignment, the inner diameter of the cylindrical member is formed in advance to be larger than the outer diameter of the male threaded portion of the bolt, thereby adjusting the bolt's position according to the misalignment and absorbing the displacement. However, taking such measures results in an increase in the outer diameter of the cylindrical component, leading to an increase in the size and weight of the cylindrical component, and also sacrificing the internal storage space of the battery pack cover. This invention has been made in view of the above circumstances, and aims to provide a battery pack fixing structure that is advantageous for smoothly fixing the battery pack to a floor panel without increasing the size of the cylindrical member. [Means for solving the problem]

[0005] To achieve the above objective, one embodiment of the present invention provides a battery pack fixing structure for fixing a battery pack to a floor panel, characterized in that the battery pack comprises: a cylindrical member that penetrates vertically from an opening in the bottom wall of the tray of the battery pack through an opening in the upper wall of the cover of the battery pack to the lower surface of the floor panel; a bolt inserted into the inside of the cylindrical member for fastening the battery pack to the floor panel; and a grommet made of an elastic material that is attached to the upper part of the cylindrical member and coupled to the edge of the opening in the upper wall of the cover. Furthermore, in one embodiment of the present invention, the grommet comprises a cylindrical grommet mounting portion attached to the upper part of the cylindrical member, a grommet lip portion coupled to the edge of the opening in the upper wall of the cover, and an annular plate-shaped connecting piece portion connecting the grommet mounting portion and the grommet lip portion, wherein the connecting piece portion includes a curved portion that protrudes in a direction intersecting the direction in which the grommet mounting portion and the grommet lip portion are connected. Furthermore, in one embodiment of the present invention, the curved portion is formed in a convex shape that protrudes radially outward from the cylindrical member. Furthermore, in one embodiment of the present invention, the grommet lip portion has an upper lip portion that contacts the upper surface of the upper wall of the cover and a lower lip portion that contacts the lower surface of the upper wall of the cover, wherein the inner diameter of the lower lip portion and the inner diameter of the upper lip portion are equal, and the outer diameter of the lower lip portion is larger than the outer diameter of the upper lip portion. Furthermore, one embodiment of the present invention is characterized in that the cylindrical member is provided with a stopper that prevents the grommet from moving downward. Furthermore, in one embodiment of the present invention, the stopper is characterized in that it extends around the entire circumference of the cylindrical member. Furthermore, one embodiment of the present invention is characterized in that a plurality of stoppers are provided at intervals in the circumferential direction of the cylindrical member. [Effects of the Invention]

[0006] According to one embodiment of the present invention, even if there is a misalignment between the central axis of the nut of the floor panel and the central axis of the opening in the upper wall of the battery pack cover, the grommet made of an elastic material is elastically deformable in the radial direction of the cylindrical member, so the cylindrical member can be displaced radially within the opening in the upper wall of the cover, and the above misalignment can be absorbed. Therefore, unlike conventional designs, it is not necessary to form the inner diameter of the cylindrical member to be considerably larger than the outer diameter of the male threaded portion of the bolt in order to absorb the displacement. This allows for a reduction in the outer diameter of the cylindrical member, and thus the cylindrical member can be made more compact. Therefore, not only can the weight of the cylindrical component be reduced, but the space occupied by the cylindrical component inside the battery pack is also reduced, which is advantageous in securing a larger storage space inside the battery pack. Furthermore, the grommet ensures that water does not enter the opening in the upper wall of the cover. Furthermore, if the connecting piece of the grommet includes a curved portion that protrudes in a direction intersecting the direction connecting the grommet mounting portion and the grommet lip portion, the misalignment between the central axis of the nut on the floor panel and the central axis of the opening in the upper wall of the battery pack cover can be easily absorbed, which is advantageous for smoothly fixing the battery pack to the floor panel. In this case, if the curved portion is formed as a convex shape that protrudes radially outward from the cylindrical member, it is advantageous in easily absorbing the misalignment between the central axis of the nut on the floor panel and the central axis of the opening in the upper wall of the battery pack cover, and is therefore advantageous in smoothly fixing the battery pack to the floor panel. Furthermore, if the outer diameter of the lower lip portion is larger than the outer diameter of the upper lip portion, it is advantageous in facilitating the installation of the grommet lip portion into the opening in the upper wall of the cover. Furthermore, providing a stopper on the cylindrical member reliably prevents the grommet from shifting position, which is advantageous in reliably preventing water from entering the opening in the upper wall of the cover by the grommet. The stopper may extend around the entire circumference of the cylindrical member, or multiple stoppers may be provided at intervals in the circumferential direction of the cylindrical member. [Brief explanation of the drawing]

[0007] [Figure 1] This is a bottom view of a vehicle to which the battery pack fixing structure according to the first embodiment is applied. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a cross-sectional view of the main part of the battery pack fixing structure according to the first embodiment. [Figure 4] This is a cross-sectional view of the main part of the battery pack fixing structure according to the second embodiment. [Modes for carrying out the invention]

[0008] (First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to Figures 1 to 3. In the following drawings, reference sign FR indicates the vehicle front, reference sign UP indicates the vehicle upper side, and reference sign HL indicates the vehicle width direction. As shown in Figures 1 and 2, the battery pack 10 is mounted on a vehicle 12 of an electric vehicle driven by a motor, such as an electric vehicle using only a motor as a drive source, a hybrid vehicle, or a plug-in hybrid vehicle capable of external charging or external power feeding, and supplies electric power to the motor.

[0009] Although not shown in the drawings, the battery pack 10 includes a plurality of battery modules, an electrical component unit that controls the battery modules and the like, and a case 18 composed of a tray 14 that accommodates the battery modules and the electrical component unit, and a cover 16 that covers an upper portion of the tray 14. As shown in Figure 1, when viewed in plan, the outline of the battery pack 10 is largely secured between the front wheel 20A and the rear wheel 20B in the front-rear direction and the vehicle width direction of the vehicle 12. As shown in Figure 2, both side portions of the battery pack 10 in the vehicle width direction are attached via attachment members 26 to a pair of side sills 24, which are vehicle body skeleton members extending in the front-rear direction of the vehicle 12 on both sides in the vehicle width direction below the floor panel 22, and the battery pack 10 is disposed at a lower portion of the vehicle 12 which is a location below the floor panel 22. Further, the battery pack 10 is fixed to the floor panel 22 by the fixing structure 28 for the battery pack 10 of the present embodiment, which is composed of a cylindrical member 30, a bolt 32, and the like. The fixing structure 28 of the present embodiment is configured to include a cylindrical member 30, a bolt 32, and a grommet 34.

[0010] As shown in Figure 3, the cylindrical members 30 are provided so as to penetrate vertically at a plurality of locations of the battery pack 10. That is, in a plurality of locations of the battery pack 10, coaxial openings 1404, 1604 are respectively provided vertically in the bottom wall 1402 of the tray 14 and the top wall 1602 of the cover 16, and the location of the battery pack 10 between the openings 1404, 1604 is a space free of battery modules and electrical components. The cylindrical member 30 is disposed in the battery pack 10 through the opening 1604 of the bottom wall 1402 of the tray 14 and the top wall 1602 of the cover 16, and the space free of battery modules and electrical components. The cylindrical member 30 is formed of a metal material, and in the present embodiment, is formed of an aluminum alloy.

[0011] The lower end of the cylindrical member 30 is provided with an annular plate-shaped flange 3002 that can abut against the lower surface of the bottom wall 1402 of the tray 14. The length of the cylindrical member 30 is set such that the upper end of the cylindrical member 30 abuts against the lower surface of the floor panel 22 in a state where the annular plate-shaped flange 3002 abuts against the lower surface of the bottom wall 1402 of the tray 14. Further, a stopper 3004 that suppresses downward movement of the grommet 34 is projectingly provided at a portion of the cylindrical member 30 located at the same height as the top wall 1602 of the cover 16. In the present embodiment, the stopper 3004 extends over the entire circumference of the cylindrical member 30. The stopper 3004 may be integrated with the cylindrical member 30, or may be a separate ring-shaped member.

[0012] The grommet 34 includes a cylindrical grommet mounting portion 34A mounted on the upper portion of the cylindrical member 30, a grommet lip portion 34B liquid-tightly coupled to the edge of the opening 1604 of the top wall 1602 of the cover 16, and an annular plate-shaped connecting piece portion 34C connecting the grommet mounting portion 34A and the grommet lip portion 34B. The position of the grommet 34 relative to the cylindrical member 30 is determined by the grommet mounting portion 34A abutting against the stopper 3004. The grommet lip portion 34B has an upper lip portion 3402 that contacts the upper surface of the top wall 1602 of the cover 16, and a lower lip portion 3404 that contacts the lower surface of the top wall 1602 of the cover 16. The inner diameter of the lower lip portion 3404 and the inner diameter of the upper lip portion 3402 are equal, and the outer diameter of the lower lip portion 3404 is larger than the outer diameter of the upper lip portion 3402. The connecting piece 34C is configured to include a curved portion 3406 that protrudes in a direction intersecting the direction of connection between the grommet mounting portion 34A and the grommet lip portion 34B and extends around the entire circumference of the connecting piece 34C. The grommet 34 is made of an elastic material, and the grommet 34 is made of synthetic resin or rubber.

[0013] The bolt 32 is a flanged bolt, inserted from below into the cylindrical member 30 and fastened to a nut 36 welded to the upper surface of the floor panel 22, thereby fixing the battery pack 10 to the floor panel 22 at multiple points. Furthermore, as shown in Figure 3, a sealing material 38 is applied to the outer circumference of the ring-shaped flange 3002 at the lower end of the cylindrical member 30, between it and the lower surface of the bottom wall 1402 of the tray 14, thereby preventing water from entering the battery pack 10.

[0014] Next, I will explain the effects and benefits. According to this embodiment, the battery pack 10 is provided with a cylindrical member 30 that extends vertically from the opening 1404 in the bottom wall 1402 of the tray 14 of the battery pack 10, through the opening 1604 in the upper wall 1602 of the cover 16 of the battery pack 10, to the lower surface of the floor panel 22. A bolt 32 is inserted into the inside of the cylindrical member 30 to fasten the battery pack 10 to the floor panel 22, and a grommet 34 made of an elastic material is attached to the top of the cylindrical member 30 and connected to the edge of the opening 1604 in the upper wall 1602 of the cover 16. Therefore, the grommet 34 reliably prevents water from entering the opening 1604 in the upper wall 1602 of the cover 16. Furthermore, the central axis of the nut 36 of the floor panel 22 and the central axis of the opening 1604 in the upper wall 1602 of the battery pack cover 16 do not necessarily coincide due to variations in part precision, resulting in misalignment.

[0015] In this embodiment, since the grommet 34 made of an elastic material is elastically deformable in the radial direction of the cylindrical member 30, the cylindrical member 30 can be displaced radially within the opening 1604 of the upper wall 1602 of the cover 16, thereby absorbing the above-mentioned displacement. Therefore, unlike in the past, it is not necessary to form the inner diameter of the cylindrical member 30 to be considerably larger than the outer diameter of the male threaded portion of the bolt 32 in order to absorb the displacement, and the outer diameter of the cylindrical member 30 can be reduced, making the cylindrical member 30 more compact. Therefore, not only can the weight of the cylindrical member 30 be reduced, but the space occupied by the cylindrical member 30 inside the battery pack 10 is also reduced, which is advantageous in securing a larger storage space inside the battery pack 10. In other words, this is advantageous for smoothly fixing the battery pack 10 to the floor panel 22 without increasing the size of the cylindrical member 30.

[0016] In this embodiment, the grommet 34 comprises a grommet mounting portion 34A, a grommet lip portion 34B, and an annular connecting piece portion 34C that connects the grommet mounting portion 34A and the grommet lip portion 34B. The connecting piece portion 34C includes a curved portion 3406 that protrudes in a direction intersecting the direction in which the grommet mounting portion 34A and the grommet lip portion 34B are connected. Therefore, when the grommet mounting portion 34A attached to the cylindrical member 30 is displaced radially in the opening 1604 of the upper wall 1602 of the cover 16, the curved portion 3406 deforms easily. This allows the discrepancy between the central axis of the nut 36 of the floor panel 22 and the central axis of the opening 1604 of the upper wall 1602 of the cover 16 of the battery pack 10 to be easily absorbed, which is advantageous for smoothly fixing the battery pack 10 to the floor panel 22.

[0017] Furthermore, in this embodiment, the grommet lip portion 34B has an upper lip portion 3402 that contacts the upper surface of the upper wall 1602 of the cover 16, and a lower lip portion 3404 that contacts the lower surface of the upper wall 1602 of the cover 16, and the outer diameter of the lower lip portion 3404 is formed to be larger than the outer diameter of the upper lip portion 3402. Therefore, this is advantageous in facilitating the process of attaching the grommet lip portion 34B to the opening 1604 in the upper wall 1602 of the cover 16.

[0018] Furthermore, since the cylindrical member 30 is provided with a stopper 3004 that suppresses the downward movement of the grommet 34, displacement of the grommet 34 can be reliably prevented, which is advantageous in reliably preventing water from entering the opening 1604 of the upper wall 1602 of the cover 16 by the grommet 34.

[0019] Furthermore, in this embodiment, since the stopper 3004 extends around the entire circumference of the cylindrical member 30, the processability of the cylindrical member 30 can be improved, which is advantageous in reducing parts costs. Furthermore, multiple stoppers 3004 may be provided at intervals around the circumferential direction of the cylindrical member 30, which is advantageous in reducing the weight of the cylindrical member 30.

[0020] (Second Embodiment) Next, a second embodiment will be described with reference to Figure 4. In the following embodiments, parts and components similar to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted. The descriptions will focus on the differences. The second embodiment differs from the first embodiment in the shape of the grommet 34. In other words, in the first embodiment, the curved portion 3406 had a convex shape that protruded upward, whereas in the second embodiment, the curved portion 3406 is formed in a convex shape that protrudes radially outward from the cylindrical member 30. In other words, in the first embodiment, since an open recess is formed above the cylindrical grommet mounting portion 34A attached to the upper part of the cylindrical member 30 and the curved portion 3406, there is a concern that water accumulated in this recess will be difficult to drain. On the other hand, in the second embodiment, since an open recess is formed radially outward between the curved portion 3406 and the grommet lip portion 34B (upper lip portion 3402), water accumulated in the recess can be easily drained. Therefore, the drainage performance at the grommet 34 can be improved, which is advantageous in reliably preventing water from entering the opening 1604 of the upper wall 1602 of the cover 16. [Explanation of Symbols]

[0021] 10 battery packs 12 vehicles 14 trays 1402 Bottom wall 1404 Opening 16 Cover 1602 Upper wall 1604 Opening 18 cases 20A Front Wheel 20B rear wheel 22 Floor Panels 24 Side sill 26 Mounting components 28 Battery pack fixing structure 30 Cylindrical member 3002 Flange 3004 Stopper 32 volts 34 Grommets 34A Grommet mounting section 34B Grommet lip section 34C connecting piece 3402 Upper lip section 3404 Lower lip section 3406 Curved section 36 nuts 38. Sealant

Claims

1. A battery pack fixing structure for fixing the battery pack to the floor panel, In the aforementioned battery pack, a cylindrical member extends vertically from an opening in the bottom wall of the tray of the battery pack, through an opening in the top wall of the cover of the battery pack, to the lower surface of the floor panel. A bolt inserted inside the cylindrical member fastens the battery pack to the floor panel, The system includes a grommet made of an elastic material that is attached to the upper part of the cylindrical member and coupled to the edge of the opening in the upper wall of the cover, A battery pack fixing structure characterized by the following features.

2. The grommet comprises a cylindrical grommet mounting portion attached to the upper part of the cylindrical member, a grommet lip portion coupled to the edge of the opening in the upper wall of the cover, and an annular plate-shaped connecting piece portion connecting the grommet mounting portion and the grommet lip portion. The connecting piece is configured to include a curved portion that protrudes in a direction intersecting the direction in which the grommet mounting portion and the grommet lip portion are connected. The battery pack fixing structure according to feature 1.

3. The curved portion is formed in a convex shape that protrudes radially outward from the cylindrical member. The battery pack fixing structure according to feature 2.

4. The grommet lip portion has an upper lip portion that contacts the upper surface of the upper wall of the cover and a lower lip portion that contacts the lower surface of the upper wall of the cover. The inner diameter of the lower lip portion and the inner diameter of the upper lip portion are equal, and the outer diameter of the lower lip portion is larger than the outer diameter of the upper lip portion. The battery pack fixing structure according to feature 2.

5. The cylindrical member is provided with a stopper that prevents the grommet from moving downward. The battery pack fixing structure according to feature 1.

6. The stopper extends around the entire circumference of the cylindrical member. The battery pack fixing structure according to claim 5.

7. The stoppers are provided in multiple locations at intervals in the circumferential direction of the cylindrical member. The battery pack fixing structure according to claim 5.

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