Vehicular lower part structure

Abstract

To provide a vehicular lower part structure that dampens vibrations of a vehicle body during vehicle running by enhancing rigidity near the center of a floor by a buffer material provided between a battery and a floor panel near the center of the floor.SOLUTION: A vehicular lower part structure, which is loaded with a battery 12, comprises a first buffer material 14 that is arranged to be sandwiched in a vertical direction of a vehicle between the battery 12 and a floor panel 22, near the center of the vehicle.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle underbody structure.

Background Art

[0002] In a vehicle with a battery mounted on the floor, a vehicle underbody structure mainly for protecting the battery has been proposed. For example, in order to reduce the impact load on the battery when a collision occurs from the side of the vehicle, there is a structure in which members are arranged so as to surround the side surface of the battery. In addition, there is a structure in which a shock-absorbing material is provided on the floor to protect the battery from the load applied during a collision.

[0003] Patent Document 1 discloses an in-vehicle structure of a battery pack disposed on the floor of a vehicle. In this in-vehicle structure, the battery pack includes a battery cell, a battery pack case in which the battery cells are arranged, and a buffer member disposed between the battery cell and the battery pack case. In this structure, the buffer member is arranged so as to be sandwiched between the battery cell and the floor or between the battery cell and the battery pack case when the battery pack case is fixed to the floor. Therefore, according to this in-vehicle structure, it is said that the battery cell can be surely fixed with a simple configuration while ensuring high reliability.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in a vehicle equipped with a battery, the installation of a lean reinforcement near the center of the floor for enhancing the strength of the vehicle body may be abolished. In this case, when the vehicle is traveling on the road surface, the amount of up-and-down deformation of the floor increases due to the vibration near the center of the floor (i.e., the vicinity where the center tunnel and the floor cross are arranged). As a result, the ride comfort of the vehicle may deteriorate. Therefore, there is a desire to reduce the vibration transmitted from the road surface during traveling to improve the ride comfort. However, the buffer member used for the purpose of battery protection described above has low rigidity and cannot suppress the up-and-down deformation of the floor.

[0006] Therefore, in this specification, a vehicle underbody structure is realized that protects the battery, improves the rigidity near the center of the floor, and suppresses the vibration of the vehicle body during vehicle traveling by providing a buffer material between the battery and the floor panel near the center of the floor.

Means for Solving the Problems

[0007] The vehicle underbody structure disclosed in this specification is a vehicle underbody structure equipped with a battery, and includes a first buffer material arranged so as to be sandwiched in the vehicle up-and-down direction between the battery and the floor panel near the center of the vehicle.

[0008] According to the above configuration, the first buffer material can enhance the rigidity of the floor near the center of the vehicle and its periphery by suppressing the vibration between the battery and the floor panel.

[0009] Further, the first buffer material is provided near the floor tunnel of the floor, which is a feature.

[0010] According to the above configuration, in particular, the rigidity near the floor tunnel can be enhanced.

[0011] Further, the vehicle underbody structure is near the center of the floor panel provided between the floor tunnel and the mounting portion of the battery to the vehicle in the vehicle width direction, and further includes a second buffer member provided outside the first buffer member, and the first buffer member is configured to have a higher rigidity than the second buffer member.

[0012] According to the above configuration, by setting the rigidity of the second buffer member lower than that of the first buffer member while ensuring the rigidity of the first buffer member, loosening of the fastening portion between the battery and the vehicle at the mounting portion of the battery to the vehicle near the second buffer member can be suppressed.

Advantages of the Invention

[0013] According to the vehicle underbody structure disclosed in this specification, the rigidity of the floor near the center of the vehicle and its surroundings can be increased.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0015] Hereinafter, the vehicle underbody structure will be described with reference to the drawings. In FIG. 1, "Fr", "Up", and "Rh" indicate the front, upper, and right side directions of the vehicle, respectively.

[0016] FIG. 1 is a plan view schematically showing a floor of a vehicle to which a vehicle lower structure according to an embodiment is applied. As shown in FIG. 1, the vehicle lower structure 10 is a structure of a vehicle equipped with a battery 12. A first buffer member 14 and a second buffer member 16 are arranged on the upper surface of the battery 12 in the vehicle up-and-down direction. Further, the battery 12 is attached to the vehicle at a bolt fastening portion 18. In FIG. 1, the first buffer member 14 is indicated by a thick black portion. Further, the bolt fastening portion 18 is indicated by a black-painted ellipse.

[0017] The figure under the thick arrow shown in FIG. 1 is a plan view showing the floor 20 of the vehicle. More specifically, the figure under the thick arrow is a figure showing a structure in which the floor 20 and its lower and peripheral members are stacked on the battery 12 (shown in the figure above the thick arrow) from above. In this figure, since the battery 12 is arranged below the floor 20, most of it is hidden in a plan view by the floor 20. Therefore, in this figure, only both end portions of the battery 12 in the vehicle width direction, that is, the portions not hidden by the floor 20, appear. Note that the portion is indicated by the reference numeral 12 in parentheses.

[0018] As shown in FIG. 1, the floor 20 has a floor panel 22, a floor tunnel 24, and a center floor cross 26. Note that, as will be described later, among the floor panels 22, the floor panel to which the second buffer member 16 is attached is indicated by a light black portion for distinction from others. Further, in a plan view, since the first buffer member 14 and the second buffer member 16 arranged below the floor 20 are hidden, they are shown as hidden lines by broken lines.

[0019] Next, with reference to FIG. 1, the configuration of the vehicle underbody structure 10 will be further described. As described above, the vehicle underbody structure 10 is configured, from bottom to top in the vehicle vertical direction, in the order of the battery 12, the first buffer member 14 and the second buffer member 16, and the floor panel 22. That is, the first buffer member 14 and the second buffer member 16 are arranged so as to be sandwiched vertically between the battery 12 and the floor panel 22. Further, the floor panel 22 is configured to be supported from below by the battery 12 to which the first buffer member 14 and the second buffer member 16 are attached. Note that the battery 12 is supported by the vehicle body by another structural member.

[0020] Also, as shown in FIG. 1, in the vehicle underbody structure 10, a plurality of the first buffer members 14 and a plurality of the second buffer members 16 are provided respectively. In this example, three first buffer members 14 and three second buffer members 16 are provided on each of the left and right sides, for a total of six, but the number is not limited to this. Also, the first buffer members 14 and the second buffer members 16 are not necessarily provided in a plurality on each of the left and right sides. For example, a configuration in which one first buffer member 14 is provided on each of the left and right sides near both sides of the floor tunnel 24 is also possible. In this case, the first buffer member 14 does not have to be small and rectangular as shown in FIG. 1. For example, the first buffer member 14 may have a substantially rectangular shape with the long side in the vehicle front-rear direction. However, when the buffer member extends along the floor tunnel 24 and has a larger shape compared to the first buffer member 14 in this example, problems such as an obstacle to the installation of other members around the floor 20 and a factor in the increase in mass may occur. Therefore, in this example, the first buffer members 14 and the second buffer members 16 are provided in a plurality on each of the left and right sides in consideration of the overall workability, mass, cost, etc. of the assembly.

[0021] Next, the first buffer member 14 will be further described. The first buffer member 14 is arranged to be sandwiched vertically between the battery 12 and the floor panel 22 near the center of the vehicle. More specifically, the first buffer member 14 is provided near the floor tunnel 24. As described above, generally, in a vehicle equipped with a battery, a lean reinforcement may not be installed near the center of the floor. For example, this may be due to reasons such as being able to relatively raise the lower end position of the battery by omitting the lean reinforcement. As a result, the rigidity near the center of the floor decreases. Specifically, the rigidity of the portion A (hereinafter referred to as "near the center A") surrounded by the two-dot chain line rectangle in FIG. 1 decreases. This is because the battery 12 and the floor panel 22 have different natural vibration frequencies, and when no member such as a lean reinforcement for suppressing the vibrations of the battery 12 and the floor panel 22 is installed, the vibrations of the floor panel 22 during vehicle travel cannot be suppressed, especially for the floor panel 22. As a result, the vibrations of the floor panel 22 such as near the center A become large, and the riding comfort of the passengers in the vehicle may deteriorate. Therefore, in this example, by arranging the first buffer member 14 near the center A of the floor 20, a configuration is adopted to suppress the vertical vibration (in other words, the vertical deformation amount) of the floor 20 at near the center A.

[0022] The first buffer member 14 in this example serves to support the floor panel 22 moving vertically due to vibrations during travel together with the battery 12, and to suppress the vibrations in which the floor panel 22 and the battery 12 affect each other. Therefore, the first buffer member 14 is set to be capable of suppressing the vibrations of the floor panel 22 and having sufficient rigidity to support the floor panel 22 together with the battery 12. That is, the first buffer member 14 is different from a buffer member with low rigidity used for the purpose of conventional battery protection. And the first buffer member 14 is set to further improve the rigidity compared to the rigidity required for the role as a buffer member between the original battery 12 and the floor panel 22 (for example, an image like a firm sponge).

[0023] Next, the second buffer member 16 will be further described. As described above, the second buffer member 16 is provided on the upper surface of the battery 12 and the lower surface of the floor panel 22 shown by the lightly shaded portion in FIG. 1. That is, like the first buffer member 14, the second buffer member 16 is arranged to be sandwiched in the vertical direction between the battery 12 and the floor panel 22. Further, the second buffer member 16 is near the center of the floor panel 22 shown by the lightly shaded portion and is provided outside the first buffer member 14. Therefore, the second buffer member 16 is provided at a position closer to the bolt fastening portion 18 than the first buffer member 14. At this time, if the rigidity of the second buffer member 16 is set to be the same as that of the first buffer member 14 whose rigidity has been improved as described above, inconvenience may occur at the bolt fastening portion 18. That is, when the rigidity of the second buffer member 16 is high, a problem may occur in that the bolt cannot be tightened at the bolt fastening portion 18 near both ends of the battery 12, which is the portion where the battery is attached to the vehicle. Therefore, the rigidity of the second buffer member 16 is set lower than that of the first buffer member 14. With such a configuration, it is possible to avoid a state in which the battery 12 is firmly attached to the vehicle at the second buffer member 16 portion (that is, an image in which the battery 12 is fixed by the second buffer member 16). As a result, loosening of the fastening at the fastening portion between the battery 12 and the vehicle (that is, the bolt fastening portion 18) can be suppressed.

[0024] The vehicle underbody structure described above was used to verify how much the vertical vibration in the floor 20 differed from the conventional case, and an example is shown in FIGS. 2 and 3. Here, FIG. 2 is a graph showing the inertance for each frequency in the vehicle underbody structure of FIG. 1, and FIG. 3 is a graph showing the vibration level for each frequency in the vehicle underbody structure of FIG. 1.

[0025] The graph shown in FIG. 2 is, more specifically, a graph representing the vertical vibration of the floor 20 in the vicinity of the floor tunnel 24, which is a part of the center floor cross member 26. In FIG. 2, the inertance for each frequency of the vehicle underbody structure according to the embodiment is shown by a solid line a, and the inertance for each frequency of the conventional vehicle underbody structure (i.e., the structure without the first buffer member 14 and the second buffer member 16 in the embodiment) is shown by a dashed line b. Note that inertance is one of the transfer functions in the vibration field and is the ratio of the force input to an object and the acceleration that can be generated thereby. Various information such as the resonance frequency and the damping ratio can be obtained from transfer functions such as this inertance. Here, as is clear from the comparison between the solid line a and the dashed line b in FIG. 2, within the range indicated by the light ink portion, the inertance is significantly different between the vehicle underbody structure according to the embodiment and the conventional vehicle underbody structure. And, when the rigidity was obtained based on the result of the inertance, one result was obtained that the rigidity around the center floor cross member 26 in the vehicle underbody structure according to the embodiment was improved by about three times compared to the conventional vehicle underbody structure.

[0026] Next, the vertical vibration of the floor 20 in the vehicle underbody structure according to the embodiment was also verified at locations other than near the rear end of the floor tunnel 24 such as the center floor cross member 26. The graph shown in FIG. 3 is a graph representing the vertical vibration of the traveling vehicle at the front side of the floor 20, more specifically, near the front side of the seat rail (not shown) of the front seat. In FIG. 3, the vibration level for each frequency of the vehicle underbody structure according to the embodiment is shown by a solid line c, and the vibration level for each frequency of the conventional vehicle underbody structure (i.e., the structure without the first buffer member 14 and the second buffer member 16 in the embodiment) is shown by a dashed line d. As is clear from the comparison between the solid line c and the dashed line d in FIG. 3, particularly at the location indicated by the black arrow, the vibration levels are significantly different between the vehicle underbody structure according to the embodiment and the conventional vehicle underbody structure. That is, in this verification, one result was obtained that the vibration level at the front side of the floor 20 in the vehicle underbody structure according to the embodiment was significantly reduced compared to the conventional vehicle underbody structure.

[0027] Note that the above description is just an example. In the vehicle underbody structure disclosed in this specification, in the vicinity of the vehicle center, a configuration including a first buffer member arranged to be sandwiched in the vehicle vertical direction between the battery and the floor panel is sufficient. Therefore, other configurations may be appropriately changed. For example, the shapes, sizes, quantities, and materials of the first buffer member and the second buffer member are not particularly limited. As an example, different materials may be used for the first buffer member and the second buffer member so that their rigidities are set differently. Also, as another example, the first buffer member and the second buffer member may be formed from the same material, and the hardness may be changed by varying the amount of crushing (i.e., the degree of compression) of each. Furthermore, foamed resins with different degrees of foaming can also be used.

Explanation of Signs

[0028] 10 Vehicle underbody structure, 12 Battery, 14 First buffer member, 16 Second buffer member, 18 Bolt fastening part, 20 Floor, 22 Floor panel, 24 Floor tunnel, 26 Center floor cross.

Claims

1. A vehicle underbody structure equipped with a battery, comprising: A vehicle underbody structure provided with a first buffer member disposed so as to be sandwiched in the vehicle vertical direction between the battery and the floor panel near the center of the vehicle.

2. The first buffer member is provided near the floor tunnel of the floor, The vehicle underbody structure according to claim 1, characterized in that.

3. In the vehicle width direction, a second buffer member is further provided near the center of the floor panel provided between the floor tunnel and the mounting portion of the battery to the vehicle, and is provided outside the first buffer member, The first buffer member is configured to have higher rigidity than the second buffer member, The vehicle underbody structure according to claim 2, characterized in that.

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