JP6380496B2 - Lower body structure of the vehicle - Google Patents

Description

  The present invention relates to a lower vehicle body structure of a vehicle provided with a cross member extending in the vehicle width direction of the vehicle, such as a tunnel cross member spanned over a tunnel portion of a floor panel.

  Various cross members extending in the vehicle width direction are attached to a body frame of an automobile or the like in order to increase its rigidity. For example, in general, a floor panel at the lower part of a vehicle body frame is provided with a tunnel portion extending in the front-rear direction of the vehicle body for passing a drive shaft or the like. In order to reinforce the rigidity of the tunnel portion, the tunnel cross member is attached so as to straddle the tunnel portion in the vehicle width direction.

  As the cross member, a member having a U-shaped or hat-shaped cross section may be used. Patent Document 1 discloses a lower vehicle body structure including a tunnel cross member in which such cross members are assembled so as to intersect in an X shape. Patent Document 2 discloses a lower body structure in which an X-shaped cross member is attached between a tunnel portion and a side sill.

Japanese Patent Application Laid-Open No. 2006-94080 JP2013-103650A

  A torsional force due to the torsion of the body frame acts on the cross member. For example, a twisting force is applied to the tunnel cross member due to a relative twist between a floor panel on the driver's seat side and a floor panel on the passenger seat side that is disposed with the tunnel portion interposed therebetween. Therefore, it is desirable that the cross member has high torsional rigidity in order to have resistance against the torsional force. For example, when the cross member is formed of an aluminum casting to reduce the weight of the vehicle body, the torsional rigidity may be increased by adopting an X-shaped cross member structure as disclosed in Patent Documents 1 and 2. Further, it is required to employ a cross member that structurally has an excellent torsional rigidity.

  An object of the present invention is to provide a lower body structure of a vehicle in which rigidity is increased by using a cross member having excellent torsional rigidity.

A vehicle lower body structure according to an aspect of the present invention includes a vehicle body frame and a composite cross member assembled to a lower portion of the vehicle body frame, the composite cross member extending in a vehicle width direction. And a second cross member portion, and a pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame, The first and second cross member portions intersect with each other, and the pair of fixing portions are integrally molded in a form of connecting both ends of the first and second cross member portions in the vehicle width direction. The cross member portion includes a first flat plate portion having a predetermined length in the vehicle width direction, and a pair of first vertical wall portions respectively disposed at both end edges of the first flat plate portion in the vehicle longitudinal direction. The second cross member portion has a vehicle width. A second flat plate portion having a predetermined length in the direction, and a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the vehicle longitudinal direction, and the first vertical wall portion and the second vertical wall portion, the first, the second cross member portion is extended through the overlapping portions which intersect each other and intersect each other at the overlapping portion, the lower vehicle body structure of a vehicle, the The pair of fixing portions includes a fixing surface facing the mounting surface of the body frame, and the first and second vertical wall portions of the first and second cross member portions extend to the fixing surface. .

According to the lower vehicle body structure of the vehicle, the composite cross member has a structure in which the first and second cross member portions intersect with each other, and the first and second cross member portions are the first and second vertical walls, respectively. Since it has a portion, it can inherently have high resistance to twisting force. In addition, the first and second vertical wall portions extend without interruption even at the overlapping portion where the first and second cross member portions intersect each other, and intersect each other at the overlapping portion. For this reason, the rigidity in the said overlapping part is strengthened and the torsional rigidity of the part in which the said composite cross member was assembled | attached can be improved. In addition, since the composite cross member is an integrally molded product of the first and second cross member portions and the pair of fixed portions, a structure in which the first and second vertical wall portions intersect at the overlapping portion can be easily performed. Can be formed. The pair of fixing portions includes a fixing surface facing a mounting surface of the body frame, and the first and second vertical wall portions of the first and second cross member portions extend to the fixing surface. Has been. By extending the first and second vertical wall portions to the fixed surface, the surface rigidity of the fixed surface can be increased.

  In the lower vehicle body structure described above, it is preferable that the intersecting portion of the first and second vertical wall portions in the overlapping portion has a quadrangular shape in plan view.

  According to this lower vehicle body structure, a pair of first vertical wall portions and a pair of second vertical wall portions form a structure having excellent rigidity in the overlapping portion. Therefore, the rigidity of the overlapping portion can be further enhanced.

  In the lower vehicle body structure, the fixed surface includes a first fixed surface on the inner side in the vehicle width direction and a second fixed surface on the outer side in the vehicle width direction, and the first fixed surface and the second fixed surface are different. It is arranged at a height position, the first fixed surface is positioned at substantially the same height as the first and second flat plate portions, and the first and second vertical wall portions are extended to the first fixed surface. It is desirable that

  According to this lower vehicle body structure, since the two fixing surfaces having different height positions are provided in the fixing portion, the torsional rigidity of the composite cross member can be increased. Further, the surface rigidity of the first fixed surface can be increased by extending the first and second vertical wall portions to the first fixed surface.

A lower body structure of a vehicle according to another aspect of the present invention includes a body frame and a composite cross member assembled to a lower portion of the body frame, and the composite cross member extends in a vehicle width direction. And a second cross member portion, and a pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame, The first and second cross member portions intersect with each other, and the pair of fixing portions are integrally molded in a form of connecting both ends in the vehicle width direction of the first and second cross member portions, The 1 cross member portion includes a first flat plate portion having a predetermined length in the vehicle width direction, and a pair of first vertical wall portions respectively disposed at both ends of the first flat plate portion in the vehicle longitudinal direction. The second cross member portion is A second flat plate portion having a predetermined length in a direction, and a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the vehicle longitudinal direction, and the first vertical wall portion And the second vertical wall portion extends through an overlapping portion where the first and second cross member portions intersect with each other, and intersects with each other at the overlapping portion. composite cross member, ing aluminum or integral molded product of the alloy.

  According to this lower body structure, the composite cross member can be reduced in weight by forming the composite cross member with an integrally molded product of aluminum or an alloy thereof. Further, by integrally molding by casting or the like, the shape of the vertical wall portion and the degree of freedom of arrangement can be increased as compared with the case where the composite cross member is formed by combining flat plates, bending the plate, or drawing.

A vehicle lower body structure according to still another aspect of the present invention includes a vehicle body frame and a composite cross member assembled to a lower portion of the vehicle body frame, wherein the composite cross member extends in a vehicle width direction. A member portion and a second cross member portion, and a pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame. The first and second cross member portions intersect with each other, and the pair of fixing portions are integrally molded in a form of connecting both ends in the vehicle width direction of the first and second cross member portions, The first cross member portion includes a first flat plate portion having a predetermined length in the vehicle width direction, and a pair of first vertical wall portions respectively disposed at both end edges of the first flat plate portion in the vehicle body front-rear direction. And having the second cross member portion A second flat plate portion having a predetermined length in the vehicle width direction, and a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the longitudinal direction of the vehicle body, The vertical wall portion and the second vertical wall portion extend through an overlapping portion where the first and second cross member portions intersect with each other, and intersect with each other at the overlapping portion. The vehicle body frame includes a floor panel having a tunnel portion extending in a vehicle longitudinal direction, and the composite cross member is a tunnel cross member attached to the vehicle body frame so as to straddle the tunnel portion in the vehicle width direction. said first, said first, second flat plate portion of the second cross member section, that having a vehicle width direction length across the tunnel portion.

  The tunnel portion of the floor panel opens to the lower side of the vehicle body, and a torsional force easily acts on the tunnel cross member straddling the tunnel portion in the vehicle width direction. Therefore, the tunnel cross member is suitable as a place where the cross member according to the present invention having high torsional rigidity is applied.

  In the lower vehicle body structure, the vehicle body frame includes a pair of side sills that extend in the vehicle front-rear direction on the vehicle width direction outer side of the floor panel, and the first, It is desirable that a floor member for connecting the end of the second cross member in the vehicle width direction and the side sill is disposed.

  According to this lower vehicle body structure, the twisting force applied to the first and second cross member portions, the compressive force in the vehicle width direction, and the like can be dispersed to the side sill through the floor member. By this dispersion, stress can be made difficult to concentrate on the composite cross member, so that fixing displacement does not occur in the pair of fixing parts, and cross-section collapse does not occur in the first and second cross members. it can.

  According to the present invention, since the composite cross member that structurally has excellent torsional rigidity is assembled to the lower part of the vehicle body frame, it is possible to provide the lower vehicle body structure of the vehicle with improved rigidity.

FIG. 1 is a bottom view of a vehicle body frame to which a vehicle lower body structure according to the present invention is applied. FIG. 2 is an enlarged perspective view of a mounting portion of the composite cross member with respect to the vehicle body frame (tunnel portion). FIG. 3 is a perspective view of the lower surface side of the composite cross member. FIG. 4 is a plan view of the lower surface side of the composite cross member. FIG. 5 is a plan view of the upper surface side of the composite cross member. FIG. 6 is a right side view of the composite cross member. FIG. 7 is a front side view of the composite cross member. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a schematic cross-sectional view showing a state in which the composite cross member is fixed to the tunnel portion.

[Outline of lower body structure of vehicle]
Hereinafter, a lower body structure of a vehicle according to an embodiment of the present invention will be described in detail based on the drawings. First, a vehicle body frame 1 to which a vehicle lower body structure according to the present invention is applied will be described with reference to FIGS. 11 and 2. FIG. 1 is a bottom view of a vehicle body frame 1 of the vehicle, and FIG. The vehicle is, for example, a four-wheeled vehicle. In FIG. 1 and other drawings, front / rear, left / right and up / down direction indications are attached. These directions are relative to the vehicle. That is, the front-rear, left-right, and up-down directions used in the following description are perpendicular to the front-rear direction (vehicle body front-rear direction), left-right direction (vehicle width direction) shown in FIG. The direction is the same as the vertical direction.

  A floor panel 11, a side sill 12, a tunnel portion 13, a dash panel 14, a front side frame 15, a rear side frame 18, and the like are disposed at the lower part of the body frame 1. A first tunnel cross member 21, a second tunnel cross member 22, and a composite tunnel cross member 23 are assembled to the lower portion of the vehicle body frame 1 so as to straddle the tunnel portion 13 in the vehicle width direction.

  The floor panel 11 is a flat plate that extends substantially in the horizontal direction, forms the bottom surface of the vehicle body frame 1 (the bottom surface of the passenger compartment), and is provided in a pair of left and right. The side sill 12 is a pair of left and right reinforcing members and has a closed cross-sectional structure. The pair of side sills 12 extend in the front-rear direction on the outside in the vehicle width direction of the right and left floor panels 11.

  The tunnel portion 13 is disposed in the center in the vehicle width direction, that is, in the middle of the pair of floor panels 11 and extends in the front-rear direction. FIG. 2 is a perspective view of the front portion of the tunnel portion 13 where the composite tunnel cross member 23 is disposed. The tunnel portion 13 is a portion having a lower surface opened and raised upward in a mountain shape with respect to the floor panel 11, and includes a pair of side plates extending in the front-rear direction and a top plate connecting the upper ends of these side plates. A drive shaft (not shown) extending in the front-rear direction is accommodated in the inner space of the tunnel portion 13.

  A pair of tunnel side frames 131 extend in the front-rear direction along the left and right hems of the tunnel portion 13. The tunnel side frame 131 is a U-shaped frame that opens upward, and forms a closed cross section with a flange plate that extends horizontally from the left and right edges of the lower portion of the tunnel portion 13. Each tunnel side frame 131 is connected to inner end portions of the left and right floor panels 11.

  The dash panel 14 is a panel that rises upward from the front end of the floor panel 11 and divides the vehicle compartment and the engine room forward and backward. Near the center of the dash panel 14 in the left-right direction, a tunnel portion connected to the front end of the tunnel portion 13 is provided. The front side frame 15 is a pair of left and right frames that extend further forward from the dash panel 14. Between the pair of front side frames 15 is an engine room E, on which an unillustrated engine unit composed of an engine, a transmission, and the like is installed. A pair of apron rains 16 is disposed on the upper side of the pair of front side frames 15 in the vehicle width direction, and a front cross member 17 is disposed on the upper front side. The rear side frame 18 is a pair of left and right frames extending rearward from the rear end of the floor panel 11. A rear cross member 19 is disposed on the rear upper side of the pair of rear side frames 18.

  The first and second tunnel cross members 21 and 22 and the composite tunnel cross member 23 are for improving the rigidity of the vehicle body frame 1 in the vehicle width direction, in particular for reinforcing the rigidity of the tunnel portion 13 opened to the lower side. A cross member extending in the vehicle width direction. A cross member (not shown) extending in the vehicle width direction is disposed between the tunnel portion 13 and the side sill 12 on the upper surface side of the floor panel 11 to improve the rigidity of the vehicle body frame 1 in the vehicle width direction. .

  The first tunnel cross member 21 is disposed near the rear end of the tunnel portion 13. A pair of fixing portions provided at both ends in the vehicle width direction of the first tunnel cross member 21 are fixed to attachment pieces provided at inner edges of the pair of tunnel side frames 131. The second tunnel cross member 22 is disposed slightly ahead of the first tunnel cross member 21. Both ends in the vehicle width direction of the second tunnel cross member 22 are attached to the lower end surface of the tunnel side frame 131, respectively.

  The composite tunnel cross member 23 is disposed at a position slightly ahead of the center of the tunnel portion 13 in the longitudinal direction of the vehicle body. As shown in FIG. 2, the composite tunnel cross member 23 is a composite of a first cross member portion 231 and a second cross member portion 232, a right fixing portion 35 and a left fixing portion 36 (a pair of fixing portions). Consists of the body. The first and second cross member portions 231 and 232 extend in the vehicle width direction and are inclined in different directions with respect to the vehicle width direction. The right and left fixing portions 35 and 36 extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions 231 and 232, and are fixed to the vehicle body frame 1 (tunnel side frame 131). Part. The composite tunnel cross member 23 is an example of the composite cross member according to the present invention, and a specific structure thereof will be described in detail later.

  Between the pair of tunnel side frames 131 (tunnel portion 13) and the pair of side sills 12, a floor lower inclined member 24 and a floor upper inclined member 25 (floor member) are arranged so as to be connected to the composite tunnel cross member 23, respectively. It is installed. The floor lower inclined member 24 is disposed in a pair on the left and right sides of the tunnel portion 13 on the lower surface side of the floor panel 11, and the right side connects the right end of the second cross member portion 232 and the right side sill 12, The left side connects the left end of the first cross member portion 231 and the left side sill 12. On the upper surface side of the floor panel 11, the floor upper inclined member 25 is disposed as a pair on the left and right side portions of the tunnel portion 13, and the right side connects the right end of the first cross member portion 231 and the right side sill 12, The left side connects the left end of the second cross member portion 232 and the left side sill 12.

[Details of composite tunnel cross member]
Hereinafter, the detailed structure of the composite tunnel cross member 23 will be described in detail with reference to FIGS. FIG. 3 is a perspective view of the lower surface side of the composite tunnel cross member 23. 4 and 5 are plan views of the lower surface side and the upper surface side of the composite tunnel cross member 23, respectively. 6 and 7 are a right side view and a front side view, respectively. 8 is a cross-sectional view taken along line VIII-VIII in FIG. In the present embodiment, an example in which the configuration of the cross member according to the present invention is applied to the composite tunnel cross member 23 arranged near the front end of the tunnel portion 13 is shown. The present invention can also be applied to a tunnel cross member disposed in the vicinity. Also, the cross member configuration according to the present invention can be applied to other cross members other than the tunnel cross member.

  In the composite tunnel cross member 23, the first cross member portion 231 and the second cross member portion 232 intersect in an X shape at the center in the vehicle width direction of the tunnel portion 13, and the first and second cross member portions 231, 232 The right and left fixing portions 35 and 36 are integrally molded in such a form that both ends in the vehicle width direction are connected to each other. A portion where the first and second cross member portions 231 and 232 intersect is an overlapping portion 37.

  The composite tunnel cross member 23 of the present embodiment is formed of an integrally molded product formed by casting aluminum or an alloy thereof. That is, the first and second cross member portions 231 and 232 and the right and left fixing portions 35 and 36 are not independent plate materials or the like, but are part of an integrally molded product. As a casting method, sand casting, die casting, die casting or the like can be employed. By using aluminum or an alloy material thereof, the composite tunnel cross member 23 can be reduced in weight. Further, by integrally molding by casting, there is an advantage that the shape of each part of the composite tunnel cross member 23 and the degree of freedom of arrangement thereof can be increased.

  The first cross member portion 231 has a first flat plate portion 31 and a pair of first vertical wall portions 32. The first cross member portion 231 connects the rear end portion 35R of the right fixing portion 35 and the front end portion 36F of the left fixing portion 36, and forms an X-shaped intersection with the second cross member portion 232 in the vehicle width direction. It has a corresponding forward / backward tilt. The first flat plate portion 31 has a vehicle width direction length (a predetermined length in the vehicle width direction) straddling the tunnel portion 13. The pair of first vertical wall portions 32 are respectively disposed at both front and rear end edges of the first flat plate portion 31 and extend in the vertical direction in a cross-sectional view in the front and rear direction, and extend to the left and right along the both end edges. ing.

  The second cross member portion 232 has a second flat plate portion 33 and a pair of second vertical wall portions 34. The second cross member portion 232 connects the front end portion 35F of the right fixing portion 35 and the rear end portion 36R of the left fixing portion 36, and forms an X-shaped intersection with the first cross member portion 231 in the vehicle width direction. It has a corresponding forward / backward tilt. The second flat plate portion 33 has a length in the vehicle width direction across the tunnel portion 13. The pair of second vertical wall portions 34 are respectively disposed at both ends in the front-rear direction of the second flat plate portion 33 and extend in the up-down direction in a cross-sectional view in the front-rear direction, and extend in the shape of a band from side to side along the both ends. ing.

  The overlapping portion 37 where the first and second cross member portions 231 and 232 intersect with each other is located in the center portion of the composite tunnel cross member 23 in the front-rear direction and the left-right direction. The overlapping portion 37 includes a common flat plate portion 371 formed by an X-shaped intersection between the first flat plate portion 31 and the second flat plate portion 33. As shown in FIGS. 4 and 5, the shared flat plate portion 371 has a quadrangular shape (diamond or parallelogram) in plan view from the upper surface. The common flat plate portion 371 is a part of the first flat plate portion 31 and a part of the second flat plate portion 33, and is a portion shared by both. In addition, the 1st flat plate part 31 and the 2nd flat plate part 33 are not superimposed on the up-down direction in the overlap part 37, but the 1st, 2nd flat plate parts 31 and 32 and the shared flat plate part 371 are the same height. Exists in the same position and has the same wall thickness.

  The pair of first vertical wall portions 32 are interrupted from the right fixing portion 35 to the left fixing portion 36 in such a manner as to cross the common flat plate portion 371 (overlapping portion 37) along both longitudinal edges of the first flat plate portion 31. It is extended without. Similarly, the pair of second vertical wall portions 34 crosses the common flat plate portion 371 along both front and rear edges of the second flat plate portion 33, and is not interrupted from the right fixing portion 35 to the left fixing portion 36. It is extended. For this reason, the first vertical wall portion 32 and the second vertical wall portion 34 intersect each other at the overlapping portion 37.

  Specifically, a pair of first vertical wall portions 32 extending in parallel at four corners of the square shared flat plate portion 371 in a top view and a predetermined crossing angle with respect to the first vertical wall portions 32 are formed. Crossing portions 372 are formed at which the pair of second vertical wall portions 34 extending in parallel intersect each other. Thus, a partition wall 373 having a quadrangular shape in a top view is formed on the periphery of the common flat plate 371. The partition wall portion 373 includes a first central piece 341 and a second central piece 342 in which a front vertical wall portion and a rear vertical wall portion of the pair of first vertical wall portions 32 respectively cross the common flat plate portion 371, and a pair of second vertical pieces. The front vertical wall portion and the rear vertical wall portion of the vertical wall portion 34 are formed by a third central piece 341 and a fourth central piece 342 that cross over the common flat plate portion 371.

  In the four intersecting portions 372 of the rectangular partition wall portion 373, the first vertical wall portion 32 and the second vertical wall portion 34 are fitted to each other in the vertical direction, or one of them is interrupted and the other is straight. Or the joint structure of both is not provided. Both are joined over the entire length of the intersecting portion 372 in the up-down direction to form an integral X-shaped intersecting portion. Such an integral intersection 372 and the common flat plate 371 as described above can be easily formed by forming the composite tunnel cross member 23 by casting.

  The protruding height of the first vertical wall portion 32 downward from the first flat plate portion 31 and the protruding height of the second vertical wall portion 34 downward from the second flat plate portion 33 are constant in the left-right direction. Moreover, the 1st vertical wall part 32 and the 2nd vertical wall part 34 have the same protrusion height. Therefore, the partition wall portion 373 is configured by first to fourth central pieces 341 to 344 having the same protruding height. For this reason, the level | step difference based on the height difference of a vertical wall part does not exist in the lower end of the cross | intersection part 372, The said lower end is flush. If there is a step at the intersecting portion 372, the step portion becomes a stress concentration portion and may be a weak point portion of mechanical strength, but such a problem does not occur in this embodiment.

  The right fixing portion 35 is a member that is substantially rectangular in top view and extends in the front-rear direction on the right end side of the intersection of the first and second cross member portions 231 and 232. The right fixing portion 35 includes a lower step portion 351 and an upper step portion 352 that are two flat plate portions having different height positions in the vertical direction. The lower step portion 351 is a flat plate portion that is disposed on the outer side in the vehicle width direction and has a relatively wide lateral width. The upper step portion 352 is a flat plate portion that is disposed on the inner side in the vehicle width direction and that is connected to the left edge of the lower step portion 351 and has a relatively narrow left-right width. Between the upper step portion 352 and the lower step portion 351, a step portion 351 </ b> E that connects the upper and lower portions is provided. The lower step portion 351 and the upper step portion 352 are portions that form two fixing surfaces (a first fixing surface F1 and a second fixing surface F2 shown in FIG. 9) that face the mounting surface of the tunnel side frame 131 and have different heights. is there.

  The lower step portion 351 has three lower bolt holes 353 aligned in the front-rear direction. These lower bolt holes 353 are holes through which fixing bolts for fixing to the tunnel side frame 131 are inserted. The upper surface side of the lower step portion 351 is a second fixing surface F2 (FIG. 5) with respect to the tunnel side frame 131. On the lower surface of the lower step portion 351, an extension portion 323 in a form in which the lower end portions of the pair of first vertical wall portions 32 are extended is erected. The vertical height of the stepped portion 351E is slightly shorter than the protruding height of the first vertical wall portion 32. The extension part 323 has a protruding height corresponding to the height difference between them. Similarly, an extended portion 343 in which a lower end portion of the pair of second vertical wall portions 34 is extended is also provided on the lower surface of the lower step portion 351.

  On the lower surface of the lower step portion 351, hole reinforcing ribs 354 that reinforce the periphery of the lower bolt hole 353 are provided upright. In the present embodiment, an example is shown in which the hole reinforcing rib 354 is erected around the two front and rear bolt holes 353 among the three lower bolt holes 353. Each of the hole reinforcing ribs 354 includes a semicircular portion surrounding the periphery of the left semicircle of the lower bolt hole 353 and a straight portion extending leftward from the semicircular portion. The left ends of the straight portions are connected to the extension 323 and the extension 343, respectively.

  The upper stage portion 352 is a flat plate portion extending in the front-rear direction, but its front portion is a shared portion with the right end portion 33R of the second flat plate portion 33 and its rear portion is shared with the right end portion 31R of the first flat plate portion 31. Only the central part in the front-rear direction is an independent part. That is, the upper stage portion 352 is located at the same height as the first and second flat plate portions 31 and 33. The upper stage 352 has three upper stage bolt holes 355 aligned in the front-rear direction within the range including the common part. The upper surface side of the upper step portion 352 becomes the first fixing surface F1 (FIG. 5) with respect to the tunnel side frame 131.

  On the lower surface side of the upper step portion 352, around the upper bolt hole 355 perforated in the shared portion (right end portion 31R) with the first flat plate portion 31 and the shared portion (right end portion 33R) with the second flat plate portion 33, Hole reinforcing ribs 356 are erected. Each of the hole reinforcing ribs 356 includes a semicircular portion surrounding the periphery of the left semicircle of the upper bolt hole 355 and a straight portion extending leftward from the semicircular portion. The left ends of the straight portions are connected to the first vertical wall portion 32 and the second vertical wall portion 34, respectively.

  The right end portions of the first vertical wall portion 32 and the second vertical wall portion 34 are extended to the upper step portion 352 serving as the first fixed surface F1. That is, the first and second vertical wall portions 32 cross the upper step portion 352 in the left-right direction, and abut on the step portion 351E except for the projecting lower end portion continuous with the extension portions 323 and 343. In the crossing portion and the abutting portion, there is no fitting portion or a butting portion, and the first and second vertical wall portions 32 and 34 and the right fixing portion 35 are integrated with each other.

  The left fixing portion 36 is a member that is symmetrical to the right fixing portion 35 described above, and has substantially the same structure as the right fixing portion 35. The left fixing portion 36 includes a lower step portion 361 and an upper step portion 362, and a step portion 361E therebetween. Three lower bolt holes 363 arranged in the front-rear direction are formed in the lower step portion 361. On the lower surface of the lower step portion 361, there are extended portions 324 and 344 having lower end portions of the first and second vertical wall portions 32 and 34 and hole reinforcing ribs 364 for reinforcing the lower bolt hole 363. It is erected. The upper stage portion 362 has three upper stage bolt holes 365 aligned in the front-rear direction. The front portion of the upper step 362 is a shared portion with the left end portion 31L of the first flat plate portion 31, and the rear portion is a shared portion with the left end portion 33L of the second flat plate portion 33. A hole reinforcing rib 366 for reinforcing the upper bolt hole 365 is erected on the lower surface of the upper step portion 362.

[Fixed structure of composite tunnel cross member]
FIG. 9 is a schematic cross-sectional view showing a state in which the composite tunnel cross member 23 is fixed to the tunnel portion 13. The tunnel portion 13 is a structure that extends in the longitudinal direction of the vehicle body and opens downward. For this reason, the tunnel portion 13 is subjected to a lateral compression force to close the opening and a lateral pulling force to open the opening. Furthermore, the left and right side sills 12 and the floor panel 11 are swung in a twisting direction, so that a twisting force also acts on the tunnel portion 13. The composite tunnel cross member 23 attached to the tunnel portion 13 so as to straddle the opening portion in the left-right direction serves to reinforce the rigidity of the opening portion of the tunnel portion 13 (first and second tunnels). The same applies to the cross members 21 and 22).

  The right fixing portion 35 and the left fixing portion 36 disposed at both ends of the composite tunnel cross member 23 are respectively an upper step portion 352 and 362 that forms the first fixing surface F1, and a lower step portion 351 that forms the second fixing surface F2. 361. Each tunnel side frame 131 disposed on both the left and right sides of the tunnel portion 13 forms a closed cross section with a flange plate 131F extending in the horizontal direction from the left and right lower edges of the tunnel portion 13. That is, the tunnel side frame 131 is a U-shaped frame that opens upward, and the upper opening is covered by the flange plate 131F.

  The upper stage portions 352 and 362 are vertically overlapped with the mounting piece 131A located inside the flange plate 131F and fastened by the upper stage fixing bolt 132. The upper fixing bolt 132 is inserted into upper bolt holes 355 and 365 bored in the upper steps 352 and 362. The lower step portions 351 and 361 are overlapped with the lower surface of the tunnel side frame 131 in the vertical direction and fastened with the lower step fixing bolt 133. The lower fixing bolt 133 is inserted into the lower bolt holes 353 and 363 drilled in the lower steps 351 and 361. The composite tunnel cross member 23 is fixed to the tunnel portion 13 (vehicle body frame 1) by inserting and fastening the upper fixing bolt 132 and the lower fixing bolt 133.

[Function and effect]
According to the lower body structure of the vehicle provided with the composite tunnel cross member 23 described above, the following operational effects are obtained. The composite tunnel cross member 23 has a structure in which the first cross member portion 231 and the second cross member portion 232 cross each other, and the first and second cross member portions 231 and 232 are respectively in the first and second longitudinal directions. Wall portions 32 and 34 are provided. For this reason, the composite tunnel cross member 23 inherently has high resistance (twisting rigidity) to the twisting force.

  In addition, the first and second vertical wall portions 32 and 34 extend without interruption even at the overlapping portion 37 where the first and second cross member portions 231 and 232 cross each other, and intersect each other at the overlapping portion 37. Thus, a square partition wall 373 is formed. For this reason, the rigidity in the overlapping portion 37 is enhanced, and the torsional rigidity of the portion where the composite tunnel cross member 23 is assembled, that is, the tunnel portion 13 can be significantly improved.

  As described above, the first and second cross member portions 231 and 232 each having the first and second vertical wall portions 32 and 34 intersect with each other, and the overlapping portion 37 where both intersect with each other has the first and second crossing portions. The vertical wall portions 32 and 34 are also extended to form an intersecting portion 372 in which the vertical wall portions 32 and 34 are integrally coupled, so that the torsional rigidity of the composite tunnel cross member 23 is structurally enhanced. . Therefore, even when the composite tunnel cross member 23 is formed of an aluminum cast product in order to reduce the weight, the composite tunnel cross member 23 can have a necessary and sufficient torsional rigidity. Furthermore, since the composite tunnel cross member 23 is an integrally molded product in which the first and second cross member portions 231 and 232 and the right and left fixing portions 35 and 36 are produced by a manufacturing method such as casting, A structure in which the two vertical wall portions 32 and 34 intersect at the overlapping portion 37 can be easily formed.

  Moreover, the partition part 373 which is the intersection part in the overlapping part 37 of the 1st, 2nd vertical wall parts 32 and 34 has a square shape by planar view by the 1st-4th center piece 341-344. Such a partition wall 373 has high resistance to twisting force, and can further increase the torsional rigidity of the overlapping portion 37 with high mass efficiency. Further, the third central piece 341 and the fourth central piece 342 are connected between the pair of first vertical wall portions 32, and the first central piece 341 and the second central piece 342 are connected between the pair of second vertical wall portions 34. It becomes a form to do. Accordingly, the rigidity of the first and second vertical wall portions 32 and 34 themselves is enhanced.

  Further, the first and second vertical wall portions 32 and 34 extend so as to straddle the right and left fixing portions 35 and 36. That is, the first and second vertical wall portions 32 and 34 are extended to the upper step portions 352 and 362, and the extension portions 323, 324, 343 and 344 are extended to the lower step portions 351 and 361. By such extension, the surface rigidity of the right and left fixing portions 35 and 36, that is, the surface rigidity of the first and second fixing surfaces F1 and F2 can be increased. In addition, since the first and second fixing surfaces F1 and F2 arranged at different height positions are provided on the right and left fixing portions 35 and 36, the torsional rigidity of the composite tunnel cross member 23 is also increased in this respect. be able to.

  According to the composite tunnel cross member 23 according to the present embodiment described above, the torsional rigidity is increased by the structure in which the first and second cross member portions 231 and 232 intersect, and the first and second in the overlapping portion 37 described above. The torsional rigidity can be further increased by the intersecting structure of the vertical wall portions 32 and 34. By assembling such a composite tunnel cross member 23 to the lower part of the vehicle body frame 1, it is possible to provide a lower vehicle body structure of a vehicle with improved rigidity.

  In addition to the above, the lower body structure of the vehicle according to the present embodiment includes the end portions in the vehicle width direction of the first and second cross member portions 231 and 232 and the side sill 12 between the pair of side sill 12 and the tunnel portion 13. It has a structure in which the lower floor inclined member 24 and the upper floor inclined member 25 to be connected are arranged (FIG. 1). For this reason, the twisting force applied to the first and second cross member portions 231 and 232, the compressive force in the vehicle width direction, and the like can be dispersed to the side sill 12 through the lower floor inclined member 24 and the upper floor inclined member 25. Due to this dispersion, stress can be made difficult to concentrate on the composite tunnel cross member 23, fixing displacement occurs in the right and left fixing portions 35, 36, and cross-section collapse occurs in the first and second cross member portions 231, 232. It can be prevented from occurring. Therefore, it is possible to provide a lower vehicle body structure for a vehicle in which the rigidity of the lower portion of the vehicle body frame 1 is further increased.

[Description of Modified Embodiment]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A various deformation | transformation embodiment can be taken.

  (1) In the above-described embodiment, an example in which only the first vertical wall portion 32 and the second vertical wall portion 34 are erected as the reinforcing bodies of the first flat plate portion 31 and the second flat plate portion 33 has been described. In addition to this, a reinforcing material such as a rib may be added as long as mass efficiency is not lowered so much. For example, in a region other than the overlapping portion 37, a rib that connects the pair of first vertical wall portions 32 or the pair of second vertical wall portions 34 in the front-rear direction may be added. Further, the first and second vertical wall portions 32 and 34 do not necessarily stand from the front and rear side edges of the first and second flat plate portions 31 and 33.

  (2) In the above embodiment, the intersecting portion (overlap portion 37) of the first and second cross member portions 231 and 232 is located at the center in the left-right direction, and is symmetrical in the front-rear and left-right directions around the overlap portion 37. The composite tunnel cross member 23 having various shapes is illustrated. This is an example, and the overlapping portion 37 may be eccentric in the front-rear direction or the left-right direction.

  (3) In the said embodiment, the 1st, 2nd cross member part 231 and 232 showed the example which comprises the 1st, 2nd flat plate parts 31 and 33 which extend linearly and are flat. The first and second flat plate portions 31 and 33 may have a curved shape, a bent shape, or a shape having an extended portion in a horizontal plane. Moreover, the 1st, 2nd flat plate parts 31 and 33 may have the part offset in the up-down direction. Alternatively, the first and second flat plate portions 31 and 33 may be offset upward or downward with respect to the right and left fixing portions 35 and 36.

DESCRIPTION OF SYMBOLS 1 Body frame 11 Floor panel 12 Side sill 13 Tunnel part 23 Composite tunnel cross member (composite cross member)
231 First cross member part 232 Second cross member part 24 Floor lower inclined member (floor member)
25 Inclined member on the floor (floor member)
31 1st flat plate part 32 1st vertical wall part 33 2nd flat plate part 34 2nd vertical wall part 35 Right fixed part (a pair of fixed part)
351 Lower part 352 Upper part 36 Left fixed part 36 (a pair of fixed parts)
361 Lower part 362 Upper part 37 Overlapping part 373 Partition part (square shape)
F1 first fixed surface F1
F2 second fixed surface F2

Claims (6)

Body frame,
A composite cross member assembled to the lower part of the vehicle body frame,
The composite cross member is
A first cross member portion and a second cross member portion extending in the vehicle width direction;
A pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame,
The first and second cross member portions intersect each other, and the pair of fixing portions are integrally molded in a form of connecting both ends of the first and second cross member portions in the vehicle width direction,
The first cross member portion includes a first flat plate portion having a predetermined length in a vehicle width direction, a pair of first vertical wall portions respectively disposed at both end edges of the first flat plate portion in the vehicle body front-rear direction, Have
The second cross member portion includes a second flat plate portion having a predetermined length in the vehicle width direction, a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the vehicle body front-rear direction, Have
The first vertical wall portion and the second vertical wall portion extend through an overlapping portion where the first and second cross member portions intersect each other, and intersect each other at the overlapping portion. In the lower body structure ,
The pair of fixing portions includes a fixing surface facing a mounting surface of the body frame,
The lower body structure of a vehicle, wherein the first and second vertical wall portions of the first and second cross member portions are extended to the fixed surface. Body frame,
  A composite cross member assembled to the lower part of the vehicle body frame,
  The composite cross member is
    A first cross member portion and a second cross member portion extending in the vehicle width direction;
    A pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame,
    The first and second cross member portions intersect each other, and the pair of fixing portions are integrally molded in a form of connecting both ends of the first and second cross member portions in the vehicle width direction,
  The first cross member portion includes a first flat plate portion having a predetermined length in a vehicle width direction, a pair of first vertical wall portions respectively disposed at both end edges of the first flat plate portion in the vehicle body front-rear direction, Have
  The second cross member portion includes a second flat plate portion having a predetermined length in the vehicle width direction, a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the vehicle body front-rear direction, Have
  The first vertical wall portion and the second vertical wall portion extend through an overlapping portion where the first and second cross member portions intersect each other, and intersect each other at the overlapping portion. In the lower body structure,
The composite cross member is a lower body structure of a vehicle made of an integrally molded product of aluminum or an alloy thereof. Body frame,
  A composite cross member assembled to the lower part of the vehicle body frame,
  The composite cross member is
    A first cross member portion and a second cross member portion extending in the vehicle width direction;
    A pair of fixing portions that extend in the longitudinal direction of the vehicle body, are respectively disposed at both ends in the vehicle width direction of the first and second cross member portions, and are fixed to the vehicle body frame,
    The first and second cross member portions intersect each other, and the pair of fixing portions are integrally molded in a form of connecting both ends of the first and second cross member portions in the vehicle width direction,
  The first cross member portion includes a first flat plate portion having a predetermined length in a vehicle width direction, a pair of first vertical wall portions respectively disposed at both end edges of the first flat plate portion in the vehicle body front-rear direction, Have
  The second cross member portion includes a second flat plate portion having a predetermined length in the vehicle width direction, a pair of second vertical wall portions respectively disposed at both end edges of the second flat plate portion in the vehicle body front-rear direction, Have
  The first vertical wall portion and the second vertical wall portion extend through an overlapping portion where the first and second cross member portions intersect each other, and intersect each other at the overlapping portion. In the lower body structure,
The vehicle body frame includes a floor panel having a tunnel portion extending in the longitudinal direction of the vehicle body,
  The composite cross member is a tunnel cross member attached to the vehicle body frame so as to straddle the tunnel portion in the vehicle width direction, and the first and second flat plate portions of the first and second cross member portions are: A lower body structure of a vehicle having a vehicle width direction length straddling the tunnel portion. The lower body structure of the vehicle according to claim 1 ,
The fixed surface includes a first fixed surface on the inner side in the vehicle width direction and a second fixed surface on the outer side in the vehicle width direction, and the first fixed surface and the second fixed surface are arranged at different height positions,
The first fixed surface is positioned at substantially the same height as the first and second flat plate portions, and the first and second vertical wall portions extend to the first fixed surface. Construction. In the lower body structure of the vehicle according to claim 3 ,
The vehicle body frame includes a pair of side sills extending in the vehicle front-rear direction on the vehicle width direction outer side of the floor panel,
A lower vehicle body structure for a vehicle, wherein a floor member for connecting the end portions in the vehicle width direction of the first and second cross members and the side sill is disposed between the pair of side sills and the tunnel portion. . In the lower body structure of the vehicle according to any one of claims 1 to 5 ,
The lower vehicle body structure of a vehicle, wherein an intersecting portion of the first and second vertical wall portions in the overlapping portion has a quadrangular shape in plan view.

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