Vehicle underbody structure

Abstract

The present invention provides a vehicle underbody structure that suppresses rear seat displacement across the entire width during a frontal collision, while also suppressing increases in cost and weight. [Solution] The lower body structure is positioned adjacent to the rear of the center of the cross member 4 in the vehicle width direction, and is provided projecting upward from the floor panel 3, and includes a bracket 5 that supports the central seating portion 25A of the rear seat 2. The height of the cross member 4 is higher than the height of the portion P below the rear end of the cushion body 23 of the floor panel 3. The cushion body 23 has a recess 23b formed in the center of the lower surface 23a of the cushion body 23 in the vehicle width direction that fits into the bracket 5, and a protrusion 23c that projects downward from the lower surface 23a of the cushion body 23 at positions on both sides in the vehicle width direction relative to the recess 23b and engages with either the cross member 4 or the raised portion 3a of the front end of the floor panel 3.

Description

Technical Field

[0001] The present invention relates to a lower body structure of a vehicle.

Background Art

[0002] Conventionally, in a collision (hereinafter referred to as a frontal collision) where a passenger slips out of a seat belt from the front of a vehicle such as an oncoming vehicle and slides down from the seat and crawls into the foot space, there is a possibility that a submarine phenomenon occurs in which the passenger fixes the torso of the passenger due to a strong impact received by the vehicle. Therefore, various structures have been proposed to suppress the submarine phenomenon.

[0003] For example, Patent Document 1 discloses a structure in which a bulging member is provided at a position below the front end of a seat cushion on the upper surface of a floor panel in order to suppress deformation of a three-seater rear seat during a frontal collision. This bulging member protrudes upward from the upper surface of the floor panel and is a long member having a mountain-shaped cross section extending over the entire width in the vehicle width direction of the seat cushion of the three-seater rear seat. By engaging such a long bulging member in a recess extending over the entire width in the vehicle width direction of the seat cushion, deformation of the rear seat during a frontal collision is suppressed, and the submarine phenomenon is suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above structure, the bulging member extending over the entire width in the vehicle width direction of the seat cushion of the three-seater rear seat is a large member that is long and heavy, which causes an increase in cost and weight.

[0006] On the other hand, if the length of the bulging member is shortened to reduce cost and mass, deformation of the seat portions on both the left and right sides of the seat cannot be suppressed, and the submarine effect of occupants sitting in the seats on both sides cannot be suppressed.

[0007] This invention has been made in view of the above circumstances, and aims to provide a vehicle underbody structure that can suppress the displacement of the rear seats over the entire width during a frontal collision, while also suppressing increases in cost and weight. [Means for solving the problem]

[0008] To solve the aforementioned problems, the lower body structure of a vehicle according to the present invention comprises: a floor panel constituting the floor surface of the vehicle body; a rear seat fixed to the upper surface of the floor panel and having a cushion extending in the vehicle width direction, and having three seating portions arranged in the vehicle width direction; a cross member provided at the front of the floor panel and extending in the vehicle width direction; and a bracket positioned adjacent to the rear side of the center portion of the cross member in the vehicle width direction, projecting upward from the floor panel, and supporting the central seating portion of the rear seat, wherein the height of the cross member is greater than the height of the portion of the floor panel below the rear end of the cushion, and the cushion has a recess formed in the center of the lower surface of the cushion in the vehicle width direction that fits into the bracket, and a protrusion that projects downward from the lower surface of the cushion at positions on both sides in the vehicle width direction relative to the recess and engages with either the cross member or a raised portion of the front end of the floor panel.

[0009] To suppress misalignment of the rear seat, which has three seating areas, the lower body structure described above is positioned adjacent to the rear of the center of the cross member in the vehicle width direction, protruding upward from the floor panel, and includes a bracket that supports the central seating area of ​​the rear seat. The height of the cross member is greater than the height of the lower part of the rear end of the cushion of the floor panel.

[0010] Furthermore, the cushion has a recess formed in the center of the vehicle width direction on the lower surface of the cushion, which fits into the bracket, and a protrusion that projects downward from the lower surface of the cushion at positions on both sides of the vehicle width direction relative to the recess, and engages with either the cross member or the raised portion of the front end of the floor panel.

[0011] As a result, a bracket protruding upward from the center in the vehicle width direction fits into a recess in the center of the rear seat cushion in the vehicle width direction, supporting the central seating area of ​​the rear seat. In the event of a frontal collision, the weight of the occupant sitting in the central seating area firmly engages the recess in the cushion with the bracket. Furthermore, since the cross member is higher than the height of the lower part of the rear end of the cushion on the floor panel, the cross member acts as a wall that prevents the cushion from moving forward. This suppresses displacement of the center of the rear seat in the vehicle width direction.

[0012] Furthermore, the protrusions on both the left and right sides of the recessed portion of the rear seat cushion engage with either the cross member or the raised portion of the front end of the floor panel, thereby suppressing misalignment of the left and right sides of the rear seat in the vehicle width direction.

[0013] In the above structure, even if the bracket is long enough to support the central seating area of ​​the rear seat, displacement can be suppressed across the entire width of the rear seat, which has three seating areas. This suppresses displacement of the rear seat across its entire width during a frontal collision, while also reducing costs and weight. As a result, it becomes possible to suppress the submarine effect of three occupants sitting in the rear seat at a low cost.

[0014] In the above-described lower body structure, it is preferable that the bracket has two or more protrusions projecting upward on both sides in the vehicle width direction of the central part of the cross member in the vehicle width direction.

[0015] In this configuration, the bracket is not a simple projection extending in the vehicle width direction, but rather has a shape with two or more protrusions, so that a pair of side walls extending in the vehicle's longitudinal direction X is formed at each protrusion. This increases the number of side walls extending in the vehicle's longitudinal direction X that bear the load during a frontal collision, thereby increasing the rigidity of the bracket. As a result, deformation of the bracket can be suppressed.

[0016] In the above-described lower body structure, it is preferable that the cross section of the cross member is composed of two closed sections when viewed in the vehicle width direction.

[0017] With this configuration, in a view in the vehicle width direction, the cross section of the cross member is composed of two closed sections, so that multiple wall surfaces are formed in the vehicle longitudinal direction X, thereby improving the rigidity (especially bending rigidity) against loads applied to the cross member during a frontal collision, and also improving rigidity in lateral collisions (side impacts) from the vehicle width direction.

[0018] Furthermore, by improving the bending rigidity of the cross member, even in a structure where the bracket is only partially provided in the central part in the width direction of the vehicle, as in the structure described above, it is possible to improve the overall rigidity of the vehicle body against loads during a frontal collision. [Effects of the Invention]

[0019] As described above, the lower body structure of the vehicle according to the present invention can suppress the displacement of the rear seats across the entire width during a frontal collision, while also suppressing increases in cost and weight. [Brief explanation of the drawing]

[0020] [Figure 1] This is a cross-sectional view showing a configuration in which a bracket is provided in the center in the width direction of a vehicle in the lower body structure of a vehicle according to an embodiment of the present invention. [Figure 2] Figure 1 is a perspective view of the floor panel and cross member, along with the bracket in the center of the vehicle width direction, as seen from the left rear and above. [Figure 3]Perspective explanatory view showing the bracket, floor panel, cross member, and cushion body and seat back of the rear seat of FIG. 1. [Figure 4] Cross-sectional explanatory view taken along line IV-IV of FIG. 1, showing a state in which the floor panel and seat cushion are cut in the vehicle width direction in front of the bracket, as seen from the front of the vehicle. [Figure 5] Bottom view of the cushion body of FIG. 3. [Figure 6] Cross-sectional view showing the structure of either the left or right side of the center in the vehicle width direction of the lower body structure of the vehicle of FIG. 1. [Figure 7] Cross-sectional explanatory view explaining that in a structure in which a bulging portion is formed above the cross member as a comparative example, during a frontal collision, the seat cushion is greatly deformed and the occupant sinks forward, resulting in a submarine phenomenon.

Mode for Carrying Out the Invention

[0021] Hereinafter, the lower body structure of a vehicle according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0022] In FIGS. 1 to 4, as the lower body structure of the vehicle, the rear seat 2 at the rear of the vehicle and the lower body structure in the periphery thereof are shown. This lower body structure includes a floor panel 3 constituting the floor surface of the vehicle body 1, a rear seat 2 fixed to the upper surface of the floor panel 3, a cross member 4 provided at a portion on the front side X1 of the vehicle of the floor panel 3 and extending in the vehicle width direction Y, and a bracket 5 that supports the rear seat 2 at a position on the rear side X2 of the vehicle in the central portion C (see FIG. 2) in the vehicle width direction Y of the cross member 4.

[0023] The rear seat 2 is fixed to the upper surface of the floor panel 3 by a rear bracket 6 and other components. Also, in FIG. 2, a cross member 7 extending in the vehicle width direction Y is provided at a portion on the rear side X2 of the vehicle of the floor panel 3 for the rear seat 2, but it is not essential in the present invention.

[0024] The height of the cross member 4 is greater than the height of the lower part P (see Figure 1) of the rear end of the cushion body 23 of the floor panel 3, which will be described later. Specifically, as shown in Figure 1, the upper surface 4a of the cross member 4 is H1 higher than the aforementioned part P of the floor panel 3.

[0025] As shown in Figure 1, the cross member 4 of this embodiment has a front member 41 with a substantially L-shaped cross section, a rear member 42 with a substantially L-shaped cross section located X2 behind the front member 41, and an inner member 43 disposed within the space formed by the front member 41 and the rear member 42. The inner member 43 divides the aforementioned space into two parts, with both ends of the inner member 43 fixed to the front member 41. As a result, when viewed in the direction perpendicular to the plane of the paper in Figure 1, i.e., in the vehicle width direction Y, the cross section of the cross member 4 is composed of two closed sections 44 and 45.

[0026] Furthermore, in this embodiment, the floor panel 3 has a raised portion 3a that rises upward at the front end adjacent to the rear X2 side of the cross member 4. This raised portion 3a also rises to the same height as the upper surface 4a of the cross member 4.

[0027] Bracket 5 is positioned adjacent to the rear of the central part C (see Figure 2) of the cross member 4 in the vehicle width direction Y. Bracket 5 is provided so as to protrude upward from the floor panel 3 and is fixed to the floor panel 3 by welding or other means.

[0028] The bracket 5 has, in terms of its specific shape, a bottom plate portion 5a and two or more (two in this embodiment) protrusions 5b projecting upward from the bottom plate portion 5a. The two protrusions 5b project upward on both sides in the vehicle width direction Y of the central portion C of the cross member 4 in the vehicle width direction Y. The two protrusions 5b are spaced apart in the vehicle width direction Y, with a recess 5d in between. The bracket 5 is formed, for example, as an integrated bag-shaped bracket by plastically deforming a single metal plate to bulge it out to have the two protrusions 5b. Each of the two protrusions 5b has a pair of side walls 5c extending in the vehicle longitudinal direction X.

[0029] The bracket 5 can support the central seating area 25A and its surrounding area in the rear seat 2 by fitting its two protrusions 5b into recesses 23b of the cushion body 23, which will be described later.

[0030] The rear seat 2 is a three-seater seat that is long in the vehicle width direction Y and fixed to the upper surface of the floor panel 3. The rear seat 2 has a seat cushion 21 in which three seating portions 25A, 25B, and 25C (see Figure 4) are formed, which are arranged in the vehicle width direction Y on which the buttocks A1 (see Figure 1) of occupant A are placed, and a seat back 22 which is erected from the rear end of the seat cushion 21 and supports the back of occupant A. The center of the seat back 22 in the vehicle width direction Y has a portion 22a that opens and closes an opening that allows access to the rear of the rear seat 2.

[0031] The seat cushion 21 has a cushion body 23 extending in the vehicle width direction Y, and a cushion cover 24 covering the cushion body 23. The cushion body 23 corresponds to the "cushion" of the present invention. The cushion body 23 is made of a foamed material such as expanded propylene and is manufactured from a material harder than the cushion cover 24 or has a hard structure. The cushion cover 24 may be manufactured from a material softer than the cushion body 23.

[0032] As shown in Figures 1 and 4-6, the cushion body 23 has a recess 23b formed in the center of the lower surface 23a of the cushion body 23 in the vehicle width direction Y, and protrusions 23c that project downward from the lower surface 23a of the cushion body 23 at positions on both sides of the recess 23b in the vehicle width direction Y.

[0033] The recess 23b in the center in the vehicle width direction is sized to fit into the two protrusions 5b of the bracket 5, specifically, it is longer than the combined length Y in the vehicle width direction of the two protrusions 5b and the recess 5d, has a depth greater than the height of the protrusions 5b, and has a width greater than the width X in the vehicle longitudinal direction of the protrusions 5b.

[0034] The protrusions 23c project downward from the lower surface 23a of the cushion body 23 at positions on both sides in the vehicle width direction Y relative to the recess 23b. There only needs to be one protrusion 23c on each side in the vehicle width direction Y relative to the recess 23b, but multiple protrusions 23c may be provided on each side as shown in Figure 5. These protrusions 23c can engage with either the cross member 4 or the raised portion 3a at the front end of the floor panel 3.

[0035] For example, a protrusion 23c located near the recess 23b in the center in the vehicle width direction may engage with the raised portion 3a, while a protrusion 23c located far from the recesses 23b on both sides in the vehicle width direction may engage with the cross member 4 because there are no raised portions 3a on either side in the vehicle width direction. Alternatively, if there are no raised portions 3a in the entire region in the vehicle width direction Y, all protrusions 23c may engage with the cross member 4.

[0036] Furthermore, the cushion body 23 of this embodiment has through holes or recesses 23d formed in positions corresponding to the left and right seating portions 25B and 25C (see Figure 4), as shown in Figures 3, 5, and 6. This reduces the reaction force on the occupant A when seated, improving seating comfort.

[0037] Furthermore, as shown in Figure 5, multiple grooves 23e are formed on the front edge X1 of the lower surface 23a of the cushion body 23. These grooves 23e engage with the protrusions 47 (see Figure 3) provided on the upper surface 4a of the cross member 4, thereby contributing to preventing displacement of the cushion body 23. Note that these grooves 23e and protrusions 47 are not essential in this invention.

[0038] (Features of this embodiment) (1) The lower body structure of the vehicle in this embodiment has the following configuration in order to suppress displacement of the rear seat 2, which has three seating portions 25A, 25B, and 25C.

[0039] The lower body structure of this embodiment is positioned adjacent to the rear of the central portion C in the vehicle width direction Y of the cross member 4, and is provided projecting upward from the floor panel 3, and includes a bracket 5 that supports the central seating portion 25A of the rear seat 2. The height of the cross member 4 is higher than the height of the lower portion P (see Figure 1) of the rear end of the cushion body 23 of the floor panel 3.

[0040] Furthermore, as shown in Figures 1 and 4-6, the cushion body 23 has a recess 23b formed in the center of the lower surface 23a of the cushion body 23 in the vehicle width direction Y, which fits into the bracket 5, and a protrusion 23c that protrudes downward from the lower surface 23a of the cushion body 23 at positions on both sides of the recess 23b in the vehicle width direction Y, and engages with either the cross member 4 or the raised portion 3a at the front end of the floor panel 3.

[0041] With the above configuration, the bracket 5, which protrudes upward at the center in the vehicle width direction Y, fits into the recess 23b in the center of the cushion body 23 of the rear seat 2 in the vehicle width direction Y, supporting the central seating portion 25A of the rear seat 2. In the event of a frontal collision, the weight of the occupant A sitting on the central seating portion 25A causes the recess 23b of the cushion body 23 and the bracket 5 to fit together firmly. Furthermore, since the cross member 4 is higher than the height of the lower part P (see Figure 1) of the rear end of the cushion body 23 of the floor panel 3, the cross member 4 acts as a wall that prevents the cushion body 23 from moving forward. This makes it possible to suppress displacement of the central part of the rear seat 2 in the vehicle width direction Y.

[0042] Furthermore, in the event of a frontal collision, the two protrusions 23c located on both the left and right sides of the recess 23b of the cushion body 23 of the rear seat 2 engage with either the cross member 4 or the raised portion 3a at the front end of the floor panel 3, thereby suppressing displacement of the left and right sides of the rear seat 2 in the vehicle width direction Y.

[0043] Furthermore, in the above-described lower body structure, even if the bracket 5 has enough length to support the central seating portion 25A of the rear seat 2, displacement can be suppressed across the entire width of the rear seat 2, which has three seating portions 25A, 25B, and 25C. This suppresses displacement of the rear seat across its entire width during a frontal collision, while also reducing costs and weight. As a result, it becomes possible to suppress the submarine effect for three occupants sitting in the rear seat at a low cost.

[0044] (2) Furthermore, in the lower body structure of this embodiment, as shown in Figure 4, the central seating area 25A is higher than the left and right seating areas 25B and 25C. Specifically, a raised portion 24a is formed in the center of the cushion surface 24 in the vehicle width direction Y. However, as shown in Figures 1 and 2, the bracket 5 protrudes upward at a position rearward from the central part C in the vehicle width direction Y of the cross member 4, that is, at a position close to the hip point A2 of occupant A sitting on the central seating area 25A. Therefore, in the event of a frontal collision, it is possible to reliably suppress the displacement of the central part of the rear seat 2 in the vehicle width direction Y. As a result, even if an occupant sitting on the central seating area 25A is sitting in a high seating position, the submarining effect can be reliably suppressed in the event of a frontal collision.

[0045] As a comparative example, in a structure where the bracket 5 is provided on the rear side of the center of the cross member 4 in the vehicle width direction, as shown in Figure 7, instead of the structure in which the bracket 5 is provided on the rear side of the center of the cross member 4 in the vehicle width direction, the bracket 50 protrudes upward at a position X1 further forward than the hip point A2 of occupant A sitting in the central seating area 25A. Therefore, in the event of a frontal collision, it is not possible to suppress the displacement of the center of the rear seat 2 in the vehicle width direction Y. As a result, as shown in Figure 7, occupant A sitting in the central seating area 25A may slip out of the seat belt S and slide down from the rear seat 2, becoming trapped in the space under the seat, resulting in a submarine phenomenon. Considering this, it is clear that the submarine phenomenon can only be suppressed by a structure in which the bracket 5 is provided on the rear side of the center of the cross member 4 in the vehicle width direction, as in the embodiment described above.

[0046] (3) Furthermore, in the lower body structure of this embodiment, as shown in Figure 1, the uppermost part 5e of the bracket 5 is located higher than the upper surface 4a of the cross member 4. Therefore, as in this embodiment, because the height position of the rear seat 2 is such that the seat surface of the central seating portion 25A (the raised portion 24a mentioned above) is higher than the left and right seat surfaces, by positioning the uppermost part 5e of the bracket 5 higher than the upper surface 4a of the cross member 4, the fitting between the bracket 5, which is located in the center in the vehicle width direction Y, and the recess 23b of the cushion body 23 can be made more reliable and robust.

[0047] (4) In the lower body structure of the vehicle according to this embodiment, the bracket 5 has two or more protrusions 5b that project upward on both sides in the vehicle width direction Y of the central part C in the vehicle width direction Y of the cross member 4.

[0048] In this configuration, the bracket 5 is not a simple projection extending in the vehicle width direction Y, but rather has a shape with two or more protrusions 5b, so that a pair of side walls 5c extending in the vehicle longitudinal direction X is formed at each protrusion 5b. This increases the number of side walls 5c extending in the vehicle longitudinal direction X that receive the load during a frontal collision, thereby increasing the rigidity of the bracket 5. As a result, deformation of the bracket 5 can be suppressed.

[0049] Note that there only need to be two or more protrusions 5b, and the number of side walls 5c can be increased as the number of protrusions 5b increases.

[0050] (5) In the lower body structure of the vehicle of this embodiment, the cross section of the cross member 4, viewed from the vehicle width direction Y, is composed of two closed sections. Therefore, by forming multiple wall surfaces in the vehicle longitudinal direction X (specifically, the longitudinal and transverse walls that make up the front member 41, rear member 42, and inner member 43 in Figure 1), the rigidity (especially bending rigidity) against loads input to the cross member 4 during a frontal collision is improved, and rigidity can also be improved in lateral collisions (side impacts) from the vehicle width direction Y.

[0051] Furthermore, by improving the bending rigidity of the cross member 4, even in a structure where the bracket 5 is only partially provided in the central part of the vehicle width direction Y, as in the structure described above, it is possible to improve the overall rigidity of the vehicle body 1 against loads during a frontal collision. [Explanation of Symbols]

[0052] 1. Vehicle body 2 Rear seats 3 Floor Panels 3a Raised area 4 Cross Members 5 brackets 5b Convex part 5c side wall 21 Seat Cushion 22 Seatback 23 Cushion body (cushion) 23a Bottom surface 23b Recess 23c protrusion 25A, 25B, 25C Seat area 44, 45 Closed section

Claims

1. The floor panel that makes up the floor surface of the vehicle body, A rear seat is fixed to the upper surface of the floor panel, has a cushion that extends in the vehicle width direction, and has three seating portions arranged in the vehicle width direction. A cross member provided at the front of the floor panel and extending in the vehicle width direction, A bracket is provided adjacent to the rear of the central part of the cross member in the vehicle width direction, protruding upward from the floor panel, and supporting the central seating portion of the rear seat. Equipped with, The height of the cross member is greater than the height of the lower part of the rear end of the cushion in the floor panel. The cushion has a recess formed in the center of the lower surface of the cushion in the vehicle width direction and fitted into the bracket, and a protrusion that protrudes downward from the lower surface of the cushion at each position on both sides in the vehicle width direction relative to the recess and engages with either the cross member or the raised portion of the front end of the floor panel. A vehicle underbody structure characterized by the following features.

2. The lower body structure of a vehicle according to claim 1, wherein the bracket has two or more protrusions projecting upward on both sides in the vehicle width direction of the central part in the vehicle width direction of the cross member.

3. The lower body structure of a vehicle according to claim 1 or 2, characterized in that, in a view in the vehicle width direction, the cross section of the cross member is composed of two closed sections.

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