US-20260125112-A1 - VEHICLE UNDERFLOOR STRUCTURE

Abstract

A vehicle underfloor structure includes a battery pack that is installed underfloor in a vehicle, and a share panel that is disposed on a lower side of the battery pack. The vehicle underfloor structure further includes an impact mitigation member that is made of a dilatant material and that is disposed between a lower face of the battery pack and the share panel. The impact mitigation member that is made of the dilatant material is disposed only between the lower face of the battery pack and the share panel.

Inventors

• Seiya ISHIKURA
• Naoyuki Yokotani

Assignees

• TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date

20260507

Application Date

20250811

Priority Date

20241106

Claims (5)

1. 1 . A vehicle underfloor structure, comprising: a battery pack that is installed underfloor in a vehicle; a share panel that is disposed on a lower side of the battery pack; and an impact mitigation member that is made of a dilatant material and that is disposed only between a lower face of the battery pack and the share panel.
2. 2 . The vehicle underfloor structure according to claim 1 , wherein the share panel is made of fiber-reinforced plastic.
3. 3 . The vehicle underfloor structure according to claim 1 , wherein: the share panel includes a share panel main portion; and the impact mitigation member fills a gap between the share panel main portion and the lower face of the battery pack with no space remaining between the share panel main portion and the lower face.
4. 4 . The vehicle underfloor structure according to claim 1 , wherein: the battery pack includes a lower case with a bottom plate portion; the bottom plate portion includes a bulging portion that partially bulges upward; and the impact mitigation member is partially provided corresponding with a portion of the bottom plate portion at which the bulging portion is situated.
5. 5 . The vehicle underfloor structure according to claim 1 , wherein the impact mitigation member is integrated with the battery pack or the share panel.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Japanese Patent Application No. 2024-194640 filed on Nov. 6, 2024. The disclosure of the above-identified application, including the specification, drawings, and claims, is incorporated by reference herein in its entirety. BACKGROUND 1. Technical Field The present disclosure relates to a vehicle underfloor structure. 2. Description of Related Art In a vehicle underfloor structure that is disclosed in WO 2012/081173, a case of a battery pack has a double-layer structure. An inner layer of the case is made of a metal or resin, and an outer layer of the case is made of a dilatant material. The member that is made of the dilatant material is arranged to protect the battery pack. SUMMARY An object of the present disclosure is to suppress cost increases in a vehicle underfloor structure that includes a member that is made of a dilatant material that protects a battery pack. A vehicle underfloor structure according to a first aspect includes a battery pack that is installed underfloor in a vehicle, a share panel that is disposed on a lower side of the battery pack, and an impact mitigation member that is made of a dilatant material and that is disposed only between a lower face of the battery pack and the share panel. In this aspect, the vehicle underfloor structure includes the battery pack that is installed underfloor in the vehicle, and the share panel that is disposed on the lower side of the battery pack. Accordingly, the share panel can protect the battery pack from fallen objects lying on the road, speed bumps, bottoming-out roads, and the like. However, in order to adequately protect the battery pack, there is a problem of increased weight, increased costs, and so forth, with respect to the share panel. Also, in order to adequately absorb impact energy, providing an up-down direction gap (impact absorbing stroke) between the battery pack and the share panel becomes necessary. Accordingly, in this aspect, the vehicle underfloor structure further includes the impact mitigation member that is made of the dilatant material and that is disposed between the lower face of the battery pack and the share panel. Thus, the impact mitigation member that is made of the dilatant material functions to protect the battery pack from underfloor impact. In particular, dilatant materials have a nature of becoming hard when subjected to a great input, and accordingly a small impact absorbing stroke is sufficient. As a result, occurrence of the above problems regarding the share panel can be suppressed. Further, in this aspect, the impact mitigation member that is made of the dilatant material is disposed only between the lower face of the battery pack and the share panel. That is to say, the impact mitigation member is not disposed on a top face side or side face sides of the battery pack, where any possibility of contact with a fallen object or the like is low. Accordingly, increase in costs due to providing the impact mitigation member that is made of the dilatant material can be suppressed. With the vehicle underfloor structure according to a second aspect, in the first aspect, the share panel is made of fiber-reinforced plastic. In this aspect, the share panel is made of fiber-reinforced plastic. Accordingly, weight of the structure can be reduced more easily as compared to a form in which the share panel is made of iron. The share panel that is made of the fiber-reinforced plastic has high functionality of suppressing penetration by sharp foreign objects, but does not absorb impact well. However, absorption of impact can be borne by the impact mitigation member that is made of the dilatant material. Note that in an embodiment described below, the share panel is provided with a share panel main portion and a reinforcing member, both of which are made of fiber-reinforced plastic, but the share panel of this aspect is not limited to this. It is sufficient for the share panel of this aspect to have at least the share panel main portion that is made of fiber-reinforced plastic. Also, the share panel of this aspect may be made up of just the share panel main portion. With the vehicle underfloor structure according to a third aspect, in the first or the second aspect, the share panel includes a share panel main portion, and the impact mitigation member fills a gap between the share panel main portion and the lower face of the battery pack with no space remaining between the share panel main portion and the lower face. In this aspect, the share panel includes the share panel main portion. The impact mitigation member fills in the gap between the share panel main portion and the lower face of the battery pack, with no space remaining therebetween. Accordingly, the battery pack can be protected more effectively. Also, the structure can be made smaller in size in the up-down direction of the vehicle, as compared to a case in which the aforementioned gap is p