Vehicle undercarriage

Abstract

To obtain a vehicle body lower part structure which enables easy separation of a dash panel from a cross member while inhibiting increase of the weight.SOLUTION: A vehicle lower part structure includes: a pair of left and right rockers provided on both sides, in a vehicle width direction, of a vehicle lower part and extending in a vehicle front-rear direction; a pair of left and right front side members 20 provided at the vehicle front side relative to the rockers and extending in the vehicle front-rear direction; a cross member 18 extending in the vehicle width direction, connecting front end portions of the pair of left and right rockers, and connecting rear end portions of the pair of left and right front side members 20; and a dash panel 46 disposed on the vehicle rear side of the cross member 18, mechanically fastened to the cross member 18 via fasteners 54A, 54B, 54C, 56A, 56B, 56C, and partitioning a vehicle cabin interior from a vehicle cabin exterior.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a structure in which a floor panel is coupled to the lower part of a dash panel that partitions an engine room and a passenger compartment of a vehicle. Further, in the structure of Patent Document 1, a dash cross is coupled to the front side surface of the vehicle of the dash panel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, instead of the current economic system, the introduction of a mechanism of circular economy is being considered. However, in a structure in which a dash panel and a dash cross (cross member) are welded together, like the structure described in Patent Document 1 above, since the two cannot be separated, it is difficult to continuously use a part of the vehicle.

[0005] An object of the present invention is to obtain a vehicle body underbody structure in which a dash panel can be easily separated from a cross member.

Means for Solving the Problems

[0006] The vehicle understructure according to claim 1 comprises: a pair of left and right rockers provided on both sides in the vehicle width direction of the underside of the vehicle and extending in the vehicle longitudinal direction; a pair of left and right front side members provided further forward than the rockers and extending in the vehicle longitudinal direction; a cross member extending in the vehicle width direction and connecting the front ends of the pair of left and right rockers and the rear ends of the pair of left and right front side members; and a dash panel positioned on the rear side of the cross member, mechanically fastened to the cross member via fasteners, and separating the interior of the vehicle from the exterior of the vehicle. The cross member is composed of a dash cross upper located on the upper side of the vehicle and a dash cross lower located on the lower side of the vehicle, with the dash cross upper and the dash cross lower each having a closed cross section structure, and the dash panel being fastened between the dash cross upper and the dash cross lower. .

[0007] In the vehicle understructure according to claim 1, a pair of rockers are provided on both sides of the underside of the vehicle in the vehicle width direction, and each rocker extends in the vehicle longitudinal direction. In addition, a pair of left and right front side members are provided on the vehicle front side of the rockers, and each front side member extends in the vehicle longitudinal direction. The front ends of the rockers and the rear ends of the front side members are connected by a cross member that extends in the vehicle width direction. A dash panel is positioned on the rear side of the cross member, and this dash panel separates the interior from the exterior of the vehicle. Furthermore, the dash panel is mechanically fastened to the cross member via fasteners. As a result, the dash panel can be easily separated from the cross member simply by removing the fasteners.

[0008] Furthermore, since there is no need to install special parts between the cross member and the dash panel, the increase in weight can be suppressed.

[0010] moreover Because the cross member has a closed cross-section structure, if the dash panel is separated from the cross member, the closed cross-section frame can be reused.

[0012] Furthermore,The closed-section structure of the dash cross upper and dash cross lower ensures the rigidity of the vehicle. Furthermore, by setting the fastening points of the dash panel between the dash cross upper and dash cross lower, vibrations input to the fastening points can be absorbed by the dash cross upper and dash cross lower, thus maintaining a good fastening state.

[0013] Claim 2 The vehicle understructure relating to the claim 1 In this configuration, a sound-insulating member is provided between the cross member and the dash panel.

[0014] Claim 2 In the vehicle understructure related to this, the sound insulation material can suppress abnormal noises generated by contact between the dash panel and the cross member. In addition, the sound insulation material can absorb at least a portion of the vibrations input to the fastening points.

[0017] Claim 3 The vehicle understructure relating to claim 1 or 2 In this configuration, the lower end of the dashboard panel is joined to the floor panel that forms the floor surface inside the vehicle.

[0018] Claim 3 In the vehicle understructure related to this, the floor panel and the dash panel are joined together, so by removing the fasteners, the floor panel and the dash panel can be separated integrally from the cross member. [Effects of the Invention]

[0019] As described above, the vehicle understructure according to the present invention provides a vehicle understructure that allows for easy separation of the dash panel from the cross member while suppressing weight increase. [Brief explanation of the drawing]

[0020] [Figure 1] This is an exploded perspective view showing the main parts of a vehicle to which the vehicle understructure according to the first embodiment is applied. [Figure 2] It is an enlarged sectional view of a main part, showing a state of being disassembled along the line 2-2 in FIG. 1. [Figure 3] It is an enlarged sectional view of a main part, showing a state where components are assembled from the state shown in FIG. 2. [Figure 4] It is an enlarged sectional view of a main part, showing a state of being disassembled the main part of a vehicle to which a vehicle lower structure according to a second embodiment is applied. [Figure 5] It is an enlarged sectional view of a main part, showing a state where components are assembled from the state shown in FIG. 4. [Figure 6] It is an enlarged sectional view of a main part, showing the main part of a vehicle to which a vehicle lower structure according to a third embodiment is applied. [Figure 7] It is a perspective view of the main part of a vehicle to which a vehicle lower structure according to a modification is applied, as viewed from the rear side of the vehicle and obliquely upward from the left side of the vehicle. [Figure 8] It is an enlarged sectional view of the main part of a vehicle lower structure according to Comparative Example 1. [Figure 9] It is an enlarged sectional view of the main part of a vehicle lower structure according to Comparative Example 2.

Mode for Carrying Out the Invention

[0021] <First Embodiment> The vehicle lower structure according to the embodiment will be described with reference to the drawings. The arrows UP, FR, and LH appropriately marked in each figure indicate the upper side in the vehicle up-down direction, the front side in the vehicle front-rear direction, and the left side of the vehicle facing the traveling direction in the vehicle 10 to which the vehicle lower structure is applied, respectively. Hereinafter, when simply explaining using the front-rear, up-down, and left-right directions, unless otherwise specified, it shall indicate the front-rear in the vehicle front-rear direction, the up-down in the vehicle up-down direction, and the left-right in the vehicle width direction.

[0022] FIG. 1 is an exploded perspective view showing the main part of the vehicle 10 to which the vehicle lower structure according to the embodiment is applied. As shown in FIG. 1, the vehicle 10 to which the vehicle lower structure is applied mainly includes a lower frame 12 and a shell body 14. The lower frame 12 constitutes the skeleton of the lower part of the vehicle 10 and includes a rocker 16 extending in the vehicle front-rear direction.

[0023] The rockers 16 are located on the outer side of the vehicle's underside in the vehicle's width direction and extend in the vehicle's longitudinal direction, with a pair of rockers 16 provided on both sides in the vehicle's width direction. Each rocker 16 is formed in a closed cross-section by extrusion molding or the like.

[0024] The front ends of a pair of rockers 16 are connected in the vehicle width direction by a cross member 18. The cross member 18 extends in the vehicle width direction, and the rear ends of the front side members 20 are connected to a position offset inward in the vehicle width direction from both ends of the cross member 18 in the vehicle width direction. Thus, the cross member 18 connects the front ends of the left and right pair of rockers 16 and the rear ends of the left and right pair of front side members 20, respectively.

[0025] A pair of front side members 20 are provided on both sides in the vehicle width direction, and each extends in the vehicle longitudinal direction. The front side members 20 are formed in a closed cross-section by extrusion molding or the like, but they may also be formed by overlapping steel plates to create a closed cross-section structure. The front ends of the pair of front side members 20 are connected in the vehicle width direction by a front cross member 22. Each of the pair of front side members 20 is also provided with a suspension tower 21.

[0026] The rear ends of a pair of rockers 16 are connected in the vehicle width direction by a cross member 19, to which the front ends of rear side members 24 are connected. A pair of rear side members 24 are provided in the vehicle width direction, and each extends in the vehicle longitudinal direction. The rear side members 24 are formed in a closed cross section by extrusion molding or the like, but a closed cross section structure may also be formed by overlapping steel plates. The rear ends of the pair of rear side members 24 are connected in the vehicle width direction by a rear cross member 26.

[0027] The shell body 14 constitutes the passenger compartment (cabin) of the vehicle 10 and mainly includes the front pillar section 30, the center pillar section 32, the rear pillar section 34, the roof side rail 35, the roof panel 36, the floor panel 38, and the outer panel 40.

[0028] The front pillar section 30 extends from the front end of the shell body 14 in the vertical direction of the vehicle. The center pillar section 32 extends further to the rear of the vehicle than the front pillar section 30 in the vertical direction of the vehicle. The rear pillar section 34 extends further to the rear of the vehicle than the center pillar section 32 in the vertical direction of the vehicle. Furthermore, the front pillar section 30, the center pillar section 32, and the rear pillar section 34 are provided on both sides in the vehicle width direction and have a closed cross-sectional structure so as to function as the skeleton of the shell body 14.

[0029] The roof side rails 35 connect the upper ends of the front pillar section 30, the center pillar section 32, and the rear pillar section 34 in the longitudinal direction of the vehicle, and are provided on both sides in the vehicle width direction. The roof panel 36 is installed between the left and right roof side rails 35, extends in the vehicle width direction and the vehicle longitudinal direction, and constitutes the ceiling of the passenger compartment.

[0030] The floor panel 38 is located at the bottom of the shell body 14 and extends in the vehicle width direction and the vehicle longitudinal direction, forming the floor surface of the passenger compartment. The floor panel 38 includes a center floor panel connected to the rocker 16 and a rear floor panel connected to the rear side member 24. The front end of the floor panel 38 is connected to the dash panel 46, which forms the front wall of the passenger compartment.

[0031] The outer panel 40 constitutes the outer panel of the shell body 14. Specifically, the outer panel 40 is provided on the outer surface of the frame of the front pillar section 30, the outer surface of the frame of the center pillar section 32, and the outer surface of the frame of the rear pillar section 34. The lower part of the outer panel 40 connects the lower ends of the front pillar section 30, the center pillar section 32, and the rear pillar section 34 in the longitudinal direction of the vehicle, and is the part that is fastened to the rocker 16.

[0032] A front opening is formed by the front pillar section 30, the center pillar section 32, the roof side rail 35, and the outer panel 40, and this front opening is closed by a front side door (not shown). Similarly, a rear opening is formed by the center pillar section 32, the rear pillar section 34, the roof side rail 35, and the outer panel 40, and this rear opening is closed by a rear side door (not shown).

[0033] (Crossmember 18) Figure 2 is an enlarged cross-sectional view of the main part, showing an exploded view of the section cut along line 2-2 in Figure 1. As shown in Figure 2, the cross member 18 is configured in a closed cross-section, including the dash cross upper 42 and the dash cross lower 44.

[0034] The dash cross upper 42 constitutes the upper part of the cross member 18 and has a closed cross section structure with the first outer panel 50 and the inner panel 48. The dash cross lower 44 is located below the dash cross upper 42 and has a closed cross section structure with the second outer panel 52 and the inner panel 48.

[0035] The first outer panel 50 is formed in a roughly hat-shaped cross-section with the rear side of the vehicle open when viewed from the vehicle width direction, and the upper end of the first outer panel 50 is a first upper flange 50A that extends in the vertical direction of the vehicle. The first upper flange 50A also has through holes 50C through which bolts are inserted, and a weld nut 54A is attached at a position corresponding to the through holes 50C.

[0036] The lower end of the first outer panel 50 has a first lower flange 50B that extends in the vertical direction of the vehicle. The upper part of the front side member 20 is joined to the first outer panel 50 by spot welding or the like, with the upper part overlapping it.

[0037] An insertion hole 50D is formed above the first lower flange 50B of the first outer panel 50, through which a bolt is inserted, and a weld nut 54B is attached at a position corresponding to the insertion hole 50D.

[0038] The second outer panel 52 is positioned below the first outer panel 50 and has a roughly hat-shaped cross-section with the rear side of the vehicle open when viewed from the vehicle width direction. The upper end of the second outer panel 52 is a second upper flange 52A that extends in the vertical direction of the vehicle. The second upper flange 52A is superimposed on the rear surface of the first lower flange 50B and joined by spot welding or the like.

[0039] The lower end of the second outer panel 52 is a second lower flange 52B that extends in the longitudinal direction of the vehicle, and the inner panel 48, which will be described later, is joined to the second lower flange 52B. Furthermore, the lower part of the front side member 20 is joined to the second outer panel 52B on the vehicle front side by spot welding or the like in an overlapping state.

[0040] The inner panel 48 is positioned opposite the first outer panel 50 and the second outer panel 52 in the vehicle's longitudinal direction, and has portions that bulge out towards the rear of the vehicle at its upper and lower ends. The upper bulge of the inner panel 48 forms a closed cross-section with the first outer panel 50. The lower bulge of the inner panel 48 also forms a closed cross-section with the second outer panel 52.

[0041] The upper end of the inner panel 48 is an inner upper flange 48A that extends in the longitudinal direction of the vehicle, and is joined to the first upper flange 50A of the first outer panel 50 by spot welding or the like while overlapping. Furthermore, since the inner upper flange 48A is formed to be shorter in length than the first upper flange 50A, the through hole 50C in the first upper flange 50A is not covered by the inner upper flange 48A.

[0042] The lower end of the inner panel 48 is an inner lower flange 48B that extends in the longitudinal direction of the vehicle, and the inner lower flange 48B and the second lower flange 52B of the second outer panel 52 are joined by spot welding or the like in an overlapping state. Furthermore, the inner lower flange 48B extends further rearward than the second lower flange 52B of the second outer panel 52, and an insertion hole 48E is formed therein through which a bolt is inserted. A weld nut 54C is attached at a position corresponding to the insertion hole 48E.

[0043] In the middle of the inner panel 48 in the vertical direction, a connecting portion 48C is formed that connects the upper bulge portion and the lower bulge portion. The connecting portion 48C is superimposed on the first outer panel 50 and has an insertion hole 48D through which a bolt is inserted. The insertion hole 48D formed in the connecting portion 48C is in communication with an insertion hole 50D formed in the first outer panel 50. The weld nuts 54A, 54B, and 54C constitute the fasteners of the present invention.

[0044] (Dash panel 46) The dash panel 46 of the shell body 14 is positioned on the rear side of the vehicle on the cross member 18 when assembled to the lower frame 12. The dash panel 46 also separates the interior of the vehicle from the exterior.

[0045] The dash panel 46 is formed in a shape that corresponds to the cross member 18 when viewed from the vehicle width direction. Specifically, the upper part of the dash panel 46 is formed in a shape that corresponds to the dash cross upper 42, and the lower part of the dash panel 46 is formed in a shape that corresponds to the dash cross lower 44.

[0046] The upper end of the dash panel 46 is a dash upper flange 46A that extends in the vertical direction of the vehicle, and an insertion hole 46D through which a bolt is inserted is formed at the base end of the dash upper flange 46A.

[0047] The lower end of the dash panel 46 is a dash lower flange 46B that extends in the longitudinal direction of the vehicle, and the front end of the floor panel 38 is joined to the underside of the dash lower flange 46B by spot welding or the like, with the two ends overlapping. Furthermore, a through hole 46E is formed on the rearward side of the dash lower flange 46B from the weld, through which a bolt is inserted. In addition, a through hole 38A is formed in the floor panel 38, and the through hole 38A and the through hole 46E are in communication with each other.

[0048] Furthermore, the vertically intermediate portion of the dash panel 46 is formed as an intermediate fastening portion 46C, which is shaped to correspond to the connecting portion 48C of the inner panel 48. The intermediate fastening portion 46C has an insertion hole 46F through which a bolt is inserted.

[0049] Figure 3 is an enlarged cross-sectional view of the main parts showing the assembled state from the state shown in Figure 2. As shown in Figure 3, with the shell body 14 assembled to the lower frame 12, the dash panel 46 is mechanically fastened to the cross member 18 via bolts 56A, 56B, and 56C that constitute the fasteners.

[0050] Specifically, the upper flange 46A of the dash panel 46 at its upper end is superimposed on the first upper flange 50A of the first outer panel 50 in the vehicle's longitudinal direction. Furthermore, a bolt 56A is inserted through the through hole 46D of the dash panel 46 and the through hole 50C of the first outer panel, and the bolt 56A is screwed into the weld nut 54A, thereby mechanically fastening the dash panel 46 to the upper part of the dash cross upper 42 (see Figure 2).

[0051] On the other hand, the lower dash flange 46B at the lower end of the dash panel 46 is superimposed on the inner lower flange 48B of the inner panel 48 in the vertical direction of the vehicle via the floor panel 38. Furthermore, a bolt 56C is inserted through the insertion hole 46E of the dash panel 46, the insertion hole 38A of the floor panel 38, and the insertion hole 48E of the inner panel 48, and the bolt 56C is screwed into the weld nut 54C, thereby mechanically fastening the lower part of the dash panel 46 to the lower part of the dash cross lower 44.

[0052] Furthermore, the intermediate fastening portion 46C of the dash panel 46 is superimposed on the inner panel 48 and the first outer panel 50. In addition, a bolt 56B is inserted through the through hole 46F of the dash panel 46, the through hole 48D of the inner panel 48, and the through hole 50D of the first outer panel 50, with these holes in communication. The dash panel 46 is mechanically fastened between the dash cross upper 42 and the dash cross lower 44 by screwing the bolt 56B into the weld nut 54B.

[0053] (action) Next, the operation of this embodiment will be explained.

[0054] In the vehicle understructure according to this embodiment, as shown in Figure 1, the front end of the rocker 16 and the rear end of the front side member 20 are connected by a cross member 18 that extends in the vehicle width direction. Also, as shown in Figure 3, a dash panel 46 is positioned on the rear side of the cross member 18, and this dash panel 46 separates the interior of the vehicle from the exterior. Furthermore, the dash panel 46 is mechanically fastened to the cross member 18 via fasteners, namely bolts 56A, 56B, 56C and weld nuts 54A, 54B, 54C. As a result, the dash panel 46 can be easily separated from the cross member 18 simply by removing these fasteners. In addition, since there is no need to provide special parts between the cross member 18 and the dash panel 46, weight increase can be suppressed.

[0055] Furthermore, in this embodiment, since the cross member 18 has a closed cross section structure, when the dash panel 46 is separated from the cross member 18, the closed cross section structure can be reused.

[0056] Furthermore, in this embodiment, the rigidity of the vehicle 10 can be ensured by the closed-section structure of the dash cross upper 42 and dash cross lower 44. In addition, by setting the fastening points of the dash panel 46 between the dash cross upper 42 and the dash cross lower 44, vibrations input to the fastening points can be absorbed by the dash cross upper 42 and dash cross lower 44, and the fastening state can be maintained in good condition.

[0057] Furthermore, in this embodiment, since the floor panel 38 and the dash panel 46 are joined by welding, the floor panel 38 and the dash panel 46 can be integrally separated from the cross member 18 by removing the fasteners. These effects will be explained in comparison with the structures of Comparative Examples 1 and 2.

[0058] (Comparative Example 1) Figure 8 is an enlarged cross-sectional view of the main part of the vehicle understructure according to Comparative Example 1. As shown in Figure 8, the vehicle 100 according to Comparative Example 1 is composed of a dash cross upper 102 and a dash cross lower 104, and the dash cross upper 102 has a closed cross section formed by the first outer panel 106 and the dash panel 110.

[0059] The dash cross lower 104 has a closed cross section formed by the second outer panel 108, the floor panel 112, and the inner panel 114.

[0060] Specifically, the upper end of the first outer panel 106 is a first upper flange 106A that extends in the vertical direction of the vehicle, and is joined to the dash panel 110 by spot welding or the like while overlapping in the front-rear direction of the vehicle. The lower end of the first outer panel 106 is a first lower flange 106B that extends in the vertical direction of the vehicle, and is joined to the second outer panel 108 by spot welding or the like while overlapping.

[0061] The upper end of the second outer panel 108 is a second upper flange 108A that extends in the vertical direction of the vehicle and overlaps with the first lower flange 106B, and is joined to the first lower flange 106B. The lower end of the second outer panel 108 is a second lower flange 108B that extends in the longitudinal direction of the vehicle, and is joined together with the floor panel 112 and inner panel 114, which will be described later.

[0062] The dash panel 110 is positioned opposite the first outer panel 106 in the vehicle's longitudinal direction, and the lower end of the dash panel 110 is joined to the floor panel 112 by welding or other means at the position of the lower end of the first outer panel 106.

[0063] The floor panel 112 is positioned opposite the second outer panel 108 in the vehicle's longitudinal direction, and the upper end of the floor panel 112 is joined to the first outer panel 106 and the inner panel 114 in a three-piece joint. Furthermore, the floor panel 112 is joined to the second outer panel 108 and the inner panel 114 in a three-piece joint at the position of the second lower flange 108B.

[0064] The inner panel 114 is positioned opposite the floor panel 112 in the vehicle's longitudinal direction, and its upper end is an inner upper flange 114A joined to the first outer panel 106 and the floor panel 112. The lower end of the inner panel 114 is an inner lower flange 114B joined to the second outer panel 108 and the floor panel 112.

[0065] In Comparative Example 1, configured as described above, the first outer panel 106, second outer panel 108, dash panel 110, floor panel 112, and inner panel 114, which constitute the dash cross upper 102 and dash cross lower 104 respectively, are joined by welding. Therefore, the dash panel 110 and floor panel 112 cannot be easily separated from the frame. In particular, since the upper end of the floor panel 112 is joined to the first outer panel 106 and inner panel 114 in a three-piece joint, it cannot be separated while leaving the frame intact.

[0066] In contrast, in this embodiment, as shown in Figure 3, the dash panel 46 and the floor panel 38 are mechanically fastened to the cross member 18 while joined together. This allows the dash panel 46 and the floor panel 38 to be easily separated from the lower frame 12 simply by removing the fasteners, bolts 56A, 56B, and 56C.

[0067] (Comparative Example 2) Figure 9 is an enlarged cross-sectional view of the main part of the vehicle understructure according to Comparative Example 2. As shown in Figure 9, the vehicle 200 according to Comparative Example 2 is composed of a dash cross upper 202 and a dash cross lower 204, and the dash cross upper 202 has a closed cross section formed by a first outer panel 206 and an inner panel 210. The dash cross lower 204 has a closed cross section formed by a second outer panel 208 and an inner panel 210.

[0068] Specifically, the upper end of the first outer panel 206 is a first upper flange 206A that extends in the vertical direction of the vehicle, and is joined to the inner panel 210 by spot welding or the like, while sandwiching the dash panel 212 and overlapping it in the front-rear direction of the vehicle.

[0069] Furthermore, the lower end of the first outer panel 206 is a second lower flange 206B that extends in the vertical direction of the vehicle, and is joined to the second outer panel 208 by spot welding or the like while overlapping them.

[0070] The upper end of the second outer panel 208 is a second upper flange 208A that extends in the vertical direction of the vehicle and overlaps with the first lower flange 206B, and is joined to the first lower flange 206B. The lower end of the second outer panel 208 is a second lower flange 208B that extends in the longitudinal direction of the vehicle, and is joined together with the floor panel 214 and the inner panel 210.

[0071] The inner panel 210 is positioned opposite the first outer panel 206 and the second outer panel 208 in the longitudinal direction of the vehicle, and the upper end of the inner panel 210 is an inner upper flange 210A that is welded together with the first upper flange 206A of the first outer panel 206 and the dash panel 212.

[0072] The lower end of the inner panel 210 is an inner lower flange 210B, which is welded together with the second lower flange 208B of the second outer panel 208 and the floor panel 214.

[0073] Furthermore, the intermediate portion of the inner panel 210 in the vehicle's vertical direction is a connecting portion 210C that connects the dash cross upper 202 and the dash cross lower 204, and is joined to the first outer panel 106 by spot welding or the like while superimposed on it.

[0074] In Comparative Example 2, which is configured as described above, the first outer panel 206, the second outer panel 208, and the inner panel 210, which constitute the dash cross upper 202 and dash cross lower 204 respectively, are joined by welding, making it difficult to easily separate the dash panel 212 and the floor panel 214 from the frame. In particular, the lower end of the dash panel 212 is joined to the first outer panel 206 and the inner panel 210 in a three-piece configuration, making it impossible to separate it while leaving the frame intact. Similarly, the floor panel 214 is joined to the second outer panel 208 and the inner panel 210 in a three-piece configuration, making it impossible to separate it while leaving the frame intact.

[0075] In contrast, in this embodiment, as shown in Figure 3, the dash panel 46 and the floor panel 38 are mechanically fastened to the cross member 18 while joined together. This allows the dash panel 46 and the floor panel 38 to be easily separated from the lower frame 12 simply by removing the fasteners, bolts 56A, 56B, and 56C.

[0076] <Second Embodiment> Next, the vehicle understructure according to the second embodiment will be described with reference to Figures 4 and 5. Components similar to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0077] Figure 4 is an enlarged cross-sectional view of a disassembled main part of a vehicle 60 to which the vehicle understructure according to the second embodiment is applied. As shown in Figure 4, the vehicle understructure according to this embodiment includes a lower frame 62, to which a shell body 64 is attached.

[0078] The cross member 65 that constitutes the lower frame 62 includes a dash cross upper 66 and a dash cross lower 68. Furthermore, the cross member 65 in this embodiment has an open cross section portion that is open on the rear side of the vehicle when viewed from the vehicle width direction.

[0079] The dash cross upper 66 constitutes the upper part of the cross member 65 and is formed in a roughly hat-shaped cross section with the rear side of the vehicle open when viewed from the vehicle width direction. The upper end of the dash cross upper 66 is a first upper flange 66A that extends in the vertical direction of the vehicle. The first upper flange 66A has through holes 66C through which bolts are inserted, and weld nuts 54D are attached at positions corresponding to the through holes 66C.

[0080] The lower end of the dash cross upper 66 has a first lower flange 66B that extends in the vertical direction of the vehicle. The upper part of the front side member 20 is joined to the dash cross upper 66 by spot welding or the like, with the upper part overlapping it.

[0081] An insertion hole 66D is formed above the first lower flange 66B of the dash cross upper 66 through which a bolt is inserted, and a weld nut 54E is attached at a position corresponding to the insertion hole 66D.

[0082] The dash cross lower 68 is positioned below the dash cross upper 66 and has a roughly hat-shaped cross section with the rear side open when viewed from the vehicle width direction. The upper end of the dash cross lower 68 is a second upper flange 68A that extends in the vertical direction of the vehicle. The second upper flange 68A is superimposed on the rear surface of the first lower flange 66B and joined by spot welding or the like.

[0083] The lower end of the dash cross lower 68 is a second lower flange 68B that extends in the longitudinal direction of the vehicle, and the floor panel 74, which will be described later, is joined to the second lower flange 68B. Furthermore, the lower part of the front side member 20 is joined to the second lower flange 68B on the vehicle front side by spot welding or the like in an overlapping state.

[0084] The dash panel 70 is positioned opposite the dash cross upper 66 and dash cross lower 68 in the vehicle's longitudinal direction and has an open section that is open on the front side of the vehicle when viewed from the vehicle's width direction. Specifically, the dash panel 70 has open sections that bulge outwards towards the rear of the vehicle at its upper and lower ends. The bulging upper section of the dash panel 70 forms a closed section with the dash cross upper 66. The bulging lower section of the dash panel 70 forms a closed section with the dash cross lower 68.

[0085] The upper end of the dash panel 70 is an upper flange 70A that extends in the vertical direction of the vehicle, and the lower end of the dash upper panel 72 is joined to the upper flange 70A by spot welding or the like, with the upper flange 70A overlapping it. In addition, the dash upper panel 72 has through holes 72A through which bolts are inserted.

[0086] The lower end of the dash panel 70 is a lower flange 70B that extends in the longitudinal direction of the vehicle, and the front end of the floor panel 74 is joined to the lower flange 70B by spot welding or the like. In addition, the floor panel 74 has through holes 74A through which bolts are inserted.

[0087] In the middle of the dash panel 70 in the vertical direction, a connecting portion 70C is formed that connects the upper bulge portion and the lower bulge portion.

[0088] Figure 5 is an enlarged cross-sectional view of the main parts showing the assembled state from the state shown in Figure 4. As shown in Figure 5, with the shell body 64 assembled to the lower frame 62, the dash upper panel 72 is mechanically fastened to the cross member 65 via bolts 56D that constitute fasteners. The dash panel 70 is mechanically fastened to the cross member 65 via bolts 56E that constitute fasteners, and the floor panel 74 is mechanically fastened to the cross member 65 via bolts 56F that constitute fasteners.

[0089] Specifically, the dash upper panel 72 is superimposed on the first upper flange 66A of the dash cross upper 66 in the vehicle's longitudinal direction. Furthermore, a bolt 56D is inserted through the insertion hole 72A of the dash upper panel 72 and the insertion hole 66C of the dash cross upper 66, and the upper part of the dash upper panel 72 and the upper part of the dash cross upper 66 are mechanically fastened together by screwing the bolt 56D into the weld nut 54D (see Figure 2).

[0090] Meanwhile, the floor panel 74, which is joined to the lower flange 70B of the lower end of the dash panel 70, is superimposed on the second lower flange 68B of the dash cross lower 68 in the vertical direction of the vehicle. Furthermore, a bolt 56F is inserted through the insertion hole 74A of the floor panel 74 and the insertion hole 68C of the dash cross lower 68, and the lower part of the dash cross lower 68 is mechanically fastened by screwing the bolt 56F into the weld nut 54F.

[0091] Furthermore, the connecting portion 70C of the dash panel 70 is overlapped with the lower end of the dash cross upper 66. In addition, a bolt 56E is inserted through the insertion hole 70E of the dash panel 70 and the insertion hole 66D of the dash cross upper 66, and the lower part of the dash panel 70 and the dash cross upper 66 are mechanically fastened together when the bolt 56E is screwed into the weld nut 54E.

[0092] As described above, in this embodiment, a closed cross section is formed by the dash cross upper 66 and the dash panel 70, and a closed cross section is formed by the dash cross lower 68 and the dash panel 70. Furthermore, in this embodiment, there is no member corresponding to the inner panel 48 of the first embodiment.

[0093] (action) Next, the operation of this embodiment will be explained.

[0094] According to the vehicle understructure of this embodiment, the shell body 64, including the dash panel 70, the upper dash panel 72, and the floor panel 74, is mechanically fastened to the cross member 65 via fasteners, namely bolts 56D, 56E, 56F and weld nuts 54D, 54E, 54F. As a result, the shell body 64, including the dash panel 70, can be easily separated from the cross member 65 simply by removing these fasteners.

[0095] Furthermore, in this embodiment, a closed cross-section structure is formed by assembling the cross member 65 and the dash panel 70. Compared to the case where the lower frame 62 side has a closed cross-section structure, the number of parts can be reduced while suppressing interference with the shape of the dash cross lower 68. Other functions are the same as in the first embodiment.

[0096] <Third Embodiment> Next, the vehicle understructure according to the third embodiment will be described with reference to Figure 6. Components similar to those in the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0097] Figure 6 is an enlarged cross-sectional view of the main part of a vehicle 80 to which the vehicle understructure according to the third embodiment is applied. As shown in Figure 6, this embodiment has the same configuration as the first embodiment except that sound insulation members 82 and 84 are provided.

[0098] The sound-insulating member 82 is provided between the dash cross upper 42 and the dash panel 46. The sound-insulating member 82 may be made of, for example, a urethane sponge or a rubber sheet. Alternatively, a porous sound-absorbing material may be used as the sound-insulating member 82.

[0099] The sound insulation member 84 is provided between the dash cross lower 44 and the dash panel 46 and is made of the same material as the sound insulation member 82.

[0100] (action) Next, the operation of this embodiment will be explained.

[0101] According to the vehicle understructure of this embodiment, the sound insulation members 82 and 84 can suppress abnormal noises generated by contact between the dash panel 46 and the cross member 18. In addition, the sound insulation members 82 and 84 can absorb at least a portion of the vibrations input to the fastening points. That is, by suppressing vibrations at the fastening points where the dash panel 46 and the cross member 18 are fastened by bolts 56B and weld nuts 54B, the fastening state can be maintained in good condition. Other functions are the same as in the first embodiment.

[0102] Although the vehicle understructure according to the embodiment has been described above, it goes without saying that the present invention can be implemented in various forms without departing from the spirit of the invention. In the first embodiment described above, as shown in Figure 3, the dash panel 46 is mechanically fastened together with the inner panel 48 and the first outer panel 50 at the intermediate fastening portion 46C, but the invention is not limited to this. For example, a modified structure in which the inner panel 48 and the first outer panel 50 are joined by welding may also be used.

[0103] (modified version) Figure 7 is a perspective view of the main part of a vehicle 10 to which the modified vehicle understructure is applied, viewed from the rear side and the upper left side of the vehicle. As shown in Figure 7, the connecting portion 48C of the inner panel 48 that constitutes the cross member 18 has an insertion hole 48D through which a bolt is inserted.

[0104] Here, the through holes 48D are formed at intervals in the vehicle width direction, and the area between adjacent through holes 48D is a welded area where the inner panel 48 and the first outer panel 50 are spot welded.

[0105] In this embodiment, the strength of the cross member 18 is improved by welding the inner panel 48 and the first outer panel 50 at the connecting portion 48C of the inner panel 48. Furthermore, by forming through holes 48D between the welded portions, the dash panel 46 can be mechanically fastened to the cross member 18.

[0106] Furthermore, although the above embodiment shows a structure in which the front side member 20 is welded to the cross members 18 and 65, the structure is not limited to this. For example, the cross members 18 and 65 and the front side member 20 may be formed integrally. Similarly, in Figure 1, the rocker 16 and the cross member 18 may be formed integrally.

[0107] Furthermore, although bolts and weld nuts were used as fasteners in the above embodiment, the invention is not limited to these, and other fasteners may be used. For example, rivets or other fasteners may be used in at least some of the fastening parts. Moreover, although the cross member 65 is composed of a dash cross upper 66 and a dash cross lower 68 in the above embodiment, the invention is not limited to this, and the cross member may be composed of only one dash cross. [Explanation of symbols]

[0108] 16 Rocka 18,65 Crossmember 20 Front side member 38,74 Floor Panel 46,70 Dash Panel 50,66 Dash Cross Upper 52,68 Dash Cross Roar 54A-54F Weld Nut (Fastener) 56A-56F Bolts (fasteners) 82,84 Sound insulation materials

Claims

1. A pair of left and right rockers are provided on both sides in the vehicle width direction at the bottom of the vehicle and extend in the vehicle longitudinal direction, A pair of left and right front side members are provided on the vehicle-front side of the rocker and extend in the vehicle-rear direction, A cross member extending in the vehicle width direction connects the front ends of the pair of left and right rockers and the rear ends of the pair of left and right front side members, A dash panel is positioned on the rear side of the cross member, mechanically fastened to the cross member via fasteners, and separates the interior of the vehicle from the exterior of the vehicle. It has, The aforementioned cross member is composed of a dash cross upper located on the upper side of the vehicle and a dash cross lower located on the lower side of the vehicle. The dash cross upper and the dash cross lower each have a closed cross-sectional structure. A vehicle understructure in which the dash panel is fastened between the dash cross upper and the dash cross lower.

2. The vehicle understructure according to claim 1, wherein a sound-insulating member is provided between the cross member and the dash panel.

3. The lower end of the dash panel is joined to a floor panel that constitutes the floor surface of the vehicle interior, as described in claim 1 or 2.

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