Underbody structure

Abstract

To provide a technology which utilizes a battery pack to improve strength of a bracket against vibration of a trailing arm.SOLUTION: A vehicle body lower structure disclosed by the specification includes: a battery pack which supplies electric power to a driving motor and is disposed below a floor panel; a bracket fixed to a rear side member and pivotally supporting a trailing arm; and a reinforcement brace fixed to the bracket and fixed to the battery pack. The bracket is located rearward of the battery pack.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vehicle underbody structure, and more particularly to a vehicle underbody structure in which a battery pack that supplies power to a driving motor is disposed under a floor panel. [Background technology]

[0002] A battery pack that supplies power to a driving motor is often located under a floor panel. Patent Documents 1 and 2 disclose such vehicle underbody structures. In the structures disclosed in Patent Documents 1 and 2, the battery pack extends to the rear of the bracket that pivotally supports the trailing arm. In other words, the bracket that pivotally supports the trailing arm is located to the side of the battery pack. In the structure disclosed in Patent Document 1, the bracket and battery pack are connected via a member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-112913 [Patent Document 2] Japanese Patent Application Publication No. 2019-156030 Summary of the Invention [Problem to be solved by the invention]

[0004] The rear end of the trailing arm is connected to the axle. The tip of the trailing arm is journaled on a bracket, which is fixed to the rear side member. Vibrations from the axle are transmitted to the bracket via the trailing arm. This specification provides a technology that uses a battery pack to increase the strength of the bracket against vibrations from the trailing arm. [Means for solving the problem]

[0005] The vehicle underbody structure disclosed in this specification includes a battery pack that supplies power to a driving motor and is disposed under a floor panel, a bracket that is fixed to a rear side member and pivotally supports a trailing arm, and a reinforcing brace that is fixed to the bracket and to the battery pack. The bracket is located rearward of the battery pack.

[0006] In the vehicle underbody structure disclosed in this specification, a bracket is positioned behind the battery pack, and the bracket and battery pack are connected by a reinforcing brace. Vibration of the axle causes the trailing arm to have a vibration component in the fore-and-aft direction. The vibration of the trailing arm is transmitted to the bracket, causing the bracket to vibrate in the fore-and-aft direction. The fore-and-aft vibration of the bracket is transmitted via the reinforcing brace to the battery pack located in front of the bracket. The battery pack bears part of the fore-and-aft vibration load applied to the bracket, increasing the bracket's strength against trailing arm vibration.

[0007] It is preferable that the fastening point between the reinforcing brace and the bracket is located at the rear of the battery pack. By locating the vibration load transmission path (i.e., the fastening point between the reinforcing brace and the bracket) at the rear of the battery pack, the vibration load that the bracket receives from the trailing arm is effectively transmitted to the battery pack.

[0008] It is recommended that the reinforcing brace be fixed to the rear of the battery pack, as this will more effectively transmit vibration loads to the battery pack. It is also recommended that the reinforcing brace be fixed to both the rear and side of the battery pack, as this will increase the strength of the connection between the reinforcing brace and the battery pack.

[0009] A horizontally extending flange may be provided at the bottom end of the bracket, and the reinforcing brace may be fixed to the flange. This increases the strength of the connection between the bracket and the reinforcing brace.

[0010] The reinforcing brace may be fixed to the underside of the battery pack. Details and further improvements of the technology disclosed in this specification will be described in the following "Description of Embodiments of the Invention". [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a bottom view of a vehicle body in which the vehicle body underbody structure of the first embodiment is adopted. [Figure 2] FIG. 2 is a side view of the vehicle body as seen from the direction of arrow II in FIG. [Figure 3] FIG. 2 is an exploded perspective view of the bracket, the reinforcing brace, and the battery pack. [Figure 4] FIG. 10 is a side view showing the vehicle underbody structure of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) A vehicle body underbody structure of an embodiment will be described with reference to the drawings. Fig. 1 is a bottom view of a vehicle body 2 that employs the vehicle body underbody structure of the embodiment. Fig. 2 is a side view of the vehicle body 2 as seen from the direction of arrow II in Fig. 1. Fig. 3 is an exploded perspective view of a battery pack 10, a bracket 20, and a reinforcing brace 30. Figs. 1 and 2 show only a portion of the vehicle body 2 (the vicinity of the bracket 20). In Fig. 2, bolts 44 (described below) and rockers 5 (described below) are not shown, and the right rear wheel 8 is drawn in imaginary lines. Note that the vehicle body is equipped with a pair of brackets on the left and right, but Figs. 1 and 2 show the bracket 20 on the right side of the vehicle body 2. The bracket on the left side of the vehicle body 2 has the same structure as the bracket 20 on the right side.

[0013] The vehicle body 2 is the body of an electric vehicle. A battery pack 10 is arranged under a floor panel 4 of the vehicle body 2. The battery pack 10 is arranged on the side of a rocker 5. The battery pack 10 supplies power to a driving motor (not shown). The battery pack 10 is fixed to the rocker 5 and a rear side member 3. The fixing structure of the battery pack 10 and the rocker 5 is not shown in the figure.

[0014] The battery pack 10 is fixed to the rocker 5 and also to the rear side member 3 via a bracket 20 and a reinforcing brace 30. The bracket 20 is fixed to the rear side member 3 and pivotally supports the trailing arm 6. The upper end of the bracket 20 is fixed to the underside of the rear side member 3. The bracket 20 is located behind the battery pack 10.

[0015] As shown in Fig. 3, the bracket 20 includes a pair of side plates 21 and a front plate 22 that connects the pair of side plates 21. Flanges 23 are provided on the upper ends of the pair of side plates 21 and the front plate 22, and the flanges 23 are fixed to the rear side member 3 (not shown in Fig. 3).

[0016] A hole 24 is formed in each of the pair of side plates 21. The tip of the trailing arm 6 fits between the pair of side plates 21, and the shaft at the tip of the trailing arm 6 is rotatably supported in the hole 24. The rear end of the trailing arm 6 supports the axle of the rear wheel (not shown).

[0017] A flange 25 is also provided at the lower end of one of the side plates 21 of the bracket 20. The flange 25 extends horizontally and has a hole 26 formed therein. The bracket 20 and the battery pack 10 are connected by a reinforcing brace 30. The reinforcing brace 30 is a steel plate. The reinforcing brace 30 has multiple holes (first hole 31, second hole 32, third hole 33, and fourth hole 34), and a bolt 41 is inserted through the first hole 31 and the hole 26 of the bracket 20 to connect the bracket 20 and the reinforcing brace 30.

[0018] A protrusion 13 is provided on the rear surface 11 of the battery pack 10, and a protrusion 14 is provided on a side surface 12 of the battery pack 10. The reinforcing brace 30 is fixed to the protrusions 13, 14. A bolt 42 that passes through a second hole 32 of the reinforcing brace 30 is fixed to the protrusion 13, and another bolt 43 that passes through a third hole 33 is fixed to the protrusion 14.

[0019] The reinforcing brace 30 is also fixed to the rocker 5. A bolt 44 passes through a fourth hole 34 in the reinforcing brace 30 and fixes it to the rocker 5. The bolt 44 is shown in the bottom view of FIG.

[0020] The features and advantages of the vehicle underbody structure of the embodiment will be described. The bracket 20 supports the trailing arm 6. The rear end of the trailing arm 6 supports the axle. The rear end of the trailing arm 6 receives longitudinal and vertical vibration loads from the axle. Therefore, the bracket 20 receives the vibration load from the trailing arm 6. Because the trailing arm 6 is supported by the bracket 20 so that its rear end can swing up and down, the bracket 20 is primarily subjected to vibration loads in the longitudinal direction. The bracket 20 is required to have the strength to withstand the longitudinal vibration load transmitted from the trailing arm 6.

[0021] As clearly shown in Figure 2, the bracket 20 is located behind the battery pack 10, and has its upper end fixed to the rear side member 3 and its lower end fixed to a reinforcing brace 30. The reinforcing brace 30 is fixed to the battery pack 10. The bracket 20, which is located behind the battery pack 10, is connected to the rear surface 11 of the battery pack 10 via the reinforcing brace 30. The use of the reinforcing brace 30 improves the strength of the bracket 20 against vibrations of the trailing arm 6.

[0022] The reinforcing brace 30 is fixed to the flange 25 at the lower end of the bracket 20. The upper end of the bracket 20 is fixed to the rear side member 3, and the lower end is fixed to the battery pack 10 via the reinforcing brace 30. Since the bracket 20 is fixed at the top and bottom, it exhibits high strength against vibration loads in the front-to-rear direction.

[0023] 1, the fastening point (bolt 41) between the bracket 20 and the reinforcing brace 30 is located at the rear of the battery pack 10, and the reinforcing brace 30 is fixed to the rear surface 11 of the battery pack 10 (more precisely, the reinforcing brace 30 is fixed to a protrusion 13 protruding from the rear surface 11). With this structure, the vibration load in the front-rear direction applied to the bracket 20 is effectively transmitted to the battery pack 10 via the reinforcing brace 30. In other words, the reinforcing brace 30 and the battery pack 10 increase the strength of the bracket 20.

[0024] The reinforcing brace 30 is fixed not only to the rear surface 11 of the battery pack 10, but also to the side surface 12 of the battery pack 10 (more precisely, the reinforcing brace 30 is fixed to a protrusion 14 protruding from the side surface 12). This structure improves the rigidity of the reinforcing brace 30 around the roll axis. The roll axis is an axis parallel to the longitudinal direction of the vehicle. The vehicle body 2 includes a pair of brackets 20 and a pair of trailing arms 6. One bracket 20 and trailing arm 6 are located near the right rear wheel 8, and the other bracket 20 and trailing arm 6 are located near the left rear wheel. Because the right rear wheel and the left rear wheel vibrate up and down independently, a moment around the roll axis acts on the rear of the vehicle body 2. Because the reinforcing brace 30 is fixed to the rear surface 11 and the side surface 12 of the battery pack 10, its rigidity around the roll axis is high. The reinforcing brace 30, which has high rigidity around the roll axis, contributes to increasing the rigidity of the vehicle body 2 around the roll axis.

[0025] (Second embodiment) A second embodiment of the vehicle underbody structure is shown in Figure 4. Figure 4 is a side view of a vehicle body 2a that employs the vehicle underbody structure of the second embodiment. The reinforcing brace 30a is fixed to the flange 25a at the lower end of the bracket 20a with two bolts 46, and is also fixed to the underside 15 of the battery pack 10 with two bolts 45. In this structure (the vehicle underbody structure of the second embodiment), the reinforcing brace 30a also contributes to increasing the strength of the bracket 20a against vibrations of the trailing arm 6.

[0026] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives alone is technically useful. [Explanation of symbols]

[0027] 2, 2a: Body 3: Rear side member 4: Floor panel 5: Rocker 6: Trailing arm 8: Right rear wheel 10: Battery pack 11: Rear surface 12: Side surface 13, 14: Protrusion 15: Underside 20, 20a: Bracket 21: Side panel 22: Front panel 23, 25, 25a: Flange 24, 26, 31, 32, 33, 34: Hole 30, 30a: Reinforcement brace 41, 42, 43, 44, 45, 46: Bolt

Claims

1. a battery pack that supplies power to a driving motor and is disposed under a floor panel; a bracket located behind the battery pack, pivotally supporting a trailing arm and fixed to a rear side member; a reinforcing brace fixed to the bracket and fixed to the battery pack; It is equipped with The reinforcing brace is fixed to the side and rear surfaces of the battery pack. Underbody structure.

2. The vehicle underbody structure according to claim 1 , wherein a fastening point between the reinforcing brace and the bracket is located rearward of the battery pack.

3. A battery pack that supplies power to a driving motor and is located under a floor panel; a bracket located behind the battery pack, pivotally supporting a trailing arm and fixed to a rear side member; a reinforcing brace fixed to the bracket and fixed to the battery pack; It is equipped with A horizontally extending flange is provided at the lower end of the bracket, The reinforcing brace is fixed to the flange. Underbody structure.

4. A vehicle underbody structure as described in claim 3, wherein the fastening point between the reinforcing brace and the bracket is located rearward of the battery pack.

5. A battery pack that supplies power to a driving motor and is located under a floor panel; a bracket located behind the battery pack, pivotally supporting a trailing arm and fixed to a rear side member; a reinforcing brace fixed to the bracket and fixed to the battery pack; It is equipped with The reinforcing brace is fixed to the bottom surface of the battery pack. Underbody structure.

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