JP6658359B2 - Lower body structure - Google Patents

Description

  The present invention relates to a vehicle body lower structure.

  Conventionally, a suspension member including a pair of left and right side rails extending in the vehicle front-rear direction and a plurality of cross members disposed between the side rails is disposed at a lower portion of the vehicle body. A lower arm mounting portion (bracket) on the vehicle front side (front side) to which the lower arm is mounted from the outside in the vehicle width direction and a lower arm mounting portion (bracket) on the vehicle rear side (rear side) are mounted on each side rail.

  For example, Patent Literature 1 discloses an arrangement in which first to fourth four cross members are disposed between a pair of left and right side rails, and a front lower arm mounting portion of the side rails in the vehicle front-rear direction. A third cross member is disposed at a mounting position of a “lower arm support” in Patent Literature 1, and first and second cross members are disposed at a mounting position of a lower arm mounting portion on the rear side.

JP 2013-203241 A

  In the vehicle body lower structure described in Patent Literature 1, the third cross member is disposed at the position of the front lower arm attachment portion of the side rail, so that the load input from the lower arm to the front lower arm attachment portion is applied to the third cross member. The suspension member is supported, and deformation of the suspension member is suppressed.

  By the way, due to the recent increase in size of components arranged near the suspension member, it has been desired to reduce the cross section of the side rails and the like. In this case, there is room for improvement in improving the rigidity of the suspension member against a load input from the front lower arm mounting portion to the side rail.

  The present invention has been made in view of the above circumstances, and has as its object to obtain a vehicle body lower structure having improved rigidity.

The vehicle body lower structure according to the first aspect of the present invention includes a pair of side rails extending in a vehicle front-rear direction and spaced apart in a vehicle width direction, and a front end of each side rail in the vehicle front-rear direction. A front lower arm mounting portion that is disposed at an intermediate portion with the rear end portion and to which a lower arm that supports the suspension is mounted, and is disposed on the rear end side of the front lower arm mounting portion on each side rail with respect to the front lower arm mounting portion, and the lower arm is mounted. A rear lower arm attachment portion, a first cross member bridged between the pair of side rails at the rear end side of the side rail at an attachment position of the front lower arm attachment portion, and the front side of the side rail. A second cross member bridged between the pair of side rails along the first cross member at a mounting position of the lower arm mounting portion , And a electric power steering apparatus is disposed a rack housing is attached to said second cross member in the longitudinal direction of the second cross member, the front lower arm mounting portion, the second cross member The vehicle has a front wall to be joined and an inner wall joined to the side rail, and an end of the front wall bent toward the rear of the vehicle is overlapped and joined to the inner wall .

  In the vehicle body lower structure according to the first aspect, the lower arm is attached to each side rail via the front lower arm attachment portion and the rear lower arm attachment portion. A second cross member bridged between a pair of side rails is disposed at a mounting position of the front lower arm mounting portion on the side rail.

  The mounting position of the front lower arm mounting portion on the side rail is an "intermediate portion" between the front end and the rear end of the side rail, and the "intermediate portion" is a position between the front end and the rear end of the side rail. It means between, not the center between the front end and the rear end.

  Further, a rack housing of the electric power steering device disposed along the longitudinal direction of the second cross member is attached to the second cross member. That is, the second cross member disposed at the mounting position of the front lower arm mounting portion on the side rail is reinforced by the electric power steering device, and the rigidity is further improved.

  Therefore, when a load is input to the side rail from the front lower arm mounting portion, the second cross member reinforced by the electric power steering device supports the load. As a result, it is possible to suppress or prevent deformation of the side rails and the like due to a load input from the lower arm.

  As described above, the rigidity can be improved in the vehicle body lower structure according to the present invention.

1 is a top view showing a vehicle body lower structure according to an embodiment of the present invention. 1 is a bottom view showing a vehicle body lower structure according to an embodiment of the present invention. 1 is a side view showing a vehicle body lower structure according to an embodiment of the present invention. (A) is a perspective view showing a front lower arm mounting bracket according to an embodiment of the present invention, and (B) is a perspective view showing a deformed state of the front lower arm mounting bracket when a load is input from the lower arm. It is a bottom view showing the front lower arm attachment bracket concerning one embodiment of the present invention. It is the perspective view seen from the vehicle front side which shows the attachment state to the side rail of the rear lower arm attachment bracket concerning one embodiment of the present invention. It is the perspective view seen from the vehicle width direction outside which shows the attachment state to the side rail of the rear lower arm attachment bracket concerning one embodiment of the present invention. FIG. 5 is a bottom view showing a state where the rear lower arm mounting bracket according to the embodiment of the present invention is mounted on a side rail. FIG. 2 is a sectional view taken along line AA of FIG. 1. It is a bottom view showing a welding process to a side rail of a rear lower arm attachment bracket concerning one embodiment of the present invention. It is the perspective view seen from slanting rear which shows the welding process to the side rail of the rear lower arm attachment bracket concerning one embodiment of the present invention. (A) is a perspective view showing a front lower arm mounting bracket according to a first comparative example, and (B) is a perspective view showing a deformed state of the front lower arm mounting bracket when a load is input from the lower arm. (A) is a side view showing a part of the side rail according to the second comparative example, and (B) is a side view showing a part of the side rail according to the present embodiment. FIG. 2 is a cross-sectional view showing a deformed state of a rear lower arm mounting bracket and a side rail when a load is input from a lower arm in a cross-sectional view taken along line AA of FIG. 1.

<Embodiment>
Hereinafter, a vehicle body lower structure 10 according to an embodiment of the present invention will be described with reference to FIGS. Note that arrows FR, arrow W, arrow RH, and arrow UP, which are appropriately shown in each figure, indicate a vehicle front, a vehicle width direction, a vehicle right side, and a vehicle upper side, respectively.

(Constitution)
As shown in FIGS. 1 and 2, the vehicle body lower structure 10 is for attaching a substantially rectangular front suspension member (hereinafter referred to as “suspension member”) 12 and a pair of lower arms (not shown) to the suspension member 12. Electric power steering device attached to the front lower arm mounting brackets (hereinafter, referred to as “front brackets”) 14A, 14B, rear lower arm mounting brackets (hereinafter, “rear brackets”) 16A, 16B, and the suspension member 12. (Hereinafter, referred to as “EPS”) 18.

  The suspension member 12 includes a pair of side rails 20A and 20B extending substantially in the vehicle front-rear direction at both ends in the vehicle width direction, a first cross member 22 connecting the side rails 20A and 20B in the vehicle width direction, and a second cross member. A member 24 and a third cross member 26 are provided.

  Since the side rails 20A and 20B are substantially symmetrical in the suspension member 12, only the side rails 20A will be described, and the components of the side rails 20B will be denoted by the same reference numerals as those of the side rails 20A, and will be denoted by B. Detailed description is omitted.

  The side rail 20A is formed in a substantially rectangular cross section by joining the side rail upper 28A and the side rail lower 30A. As shown in FIGS. 1 and 2, the side rails 20A extend from a vehicle front end (hereinafter, referred to as "front end") 33A to a vehicle rear end (hereinafter, "rear end") in plan view. ) Is formed so as to be inclined toward the inside in the vehicle width direction toward 35A, to be curved outward in the vehicle width direction at the rear end 35A side, and to be inclined outwardly in the vehicle width direction. In the side rail 20A, the engine mounting bracket 31A is mounted between the front bracket 14A and the rear bracket 16A.

  As shown in FIG. 3, the side rail 20A is a horizontal portion 32A that extends horizontally from the front end portion 33A to a position before the second cross member 24 is connected, and extends rearward from the rear end of the horizontal portion 32A. And a horizontal portion 36A extending horizontally from the rear end of the inclined portion 34A to the rear end 35A of the side rail 20A.

  As shown in FIGS. 1 and 2, the vehicle extends in the vehicle width direction between the mounting position of the rear bracket 16A of the side rail 20A (horizontal portion 36A) and the mounting position of the rear bracket 16B of the side rail 20B. The existing first cross member 22 is attached.

  The second cross member 24 is provided so as to connect the lower end of the inclined portion 34A of the side rail 20A and the lower end of the inclined portion 34B of the side rail 20B. The second cross member 24 includes a second cross member upper 24A and a second cross member lower 24B, and has a rectangular cross section by being joined. The second cross member upper 24A is joined to the side rail upper 28A, and the second cross member lower 24B is joined to the front bracket 14A.

  A third cross member 26 extending in the vehicle width direction is provided so as to connect the front end 33A of the side rail 20A and the front end 33B of the side rail 20B. At both ends in the vehicle width direction of the third cross member 26, mounting portions 38A and 38B having a greater thickness than the central portion are formed.

  As shown in FIGS. 1 and 2, the EPS 18 includes a rack housing 40 extending in the vehicle width direction, an ECU that calculates a power assist amount for the rack housing 40, and a motor that is driven according to the power assist amount. And a driving unit 42.

  The rack housing 40 is arranged so that the longitudinal direction thereof is along the longitudinal direction (vehicle width direction) of the second cross member 24 by being fastened to the attaching portions 38A, 38B of the third cross member 26 by the fastening portions 44A, 44B. Is done. The rack housing 40 is fastened to the second cross member 24 via the fastening portion 44C at an intermediate position between the fastening portions 44A and 44B in the vehicle width direction.

  As shown in FIG. 3, a front bracket 14A is attached to the outer side in the vehicle width direction of the inclined portion 34A of the side rail 20A.

  As shown in FIGS. 3 and 4A, the front bracket 14A includes a bracket body 50 for pivotally supporting a pin of a lower arm (not shown), and an upper plate 52 disposed above the bracket body 50. I have.

  As shown in FIG. 4A, the bracket main body 50 includes a substantially rectangular bottom wall 54, and a substantially rectangular inner wall 56 extending upward from the inner end of the bottom wall 54 in the vehicle width direction. A substantially rectangular front wall 58 extending upward from the front end of the bottom wall 54 to the vehicle, and a substantially rectangular rear wall 60 extending upward from the rear end of the bottom wall 54 to the vehicle.

  A hole 62 is provided in each of the front wall 58 and the rear wall 60. The pin of the lower arm is pivotally supported between the holes 62, 62 so that the lower arm is supported by the front bracket 14A. As shown in FIG. 4A, the bracket body 50 is formed with a flange portion 59 which is bent forward from the vehicle width direction outer end portion of the front wall 58 to the upper end thereof. A flange portion 61 is formed which is bent from the widthwise outer end to the upper end toward the vehicle rear side.

  The inner wall 56 and the rear wall 60 of the bracket body 50 are joined to the side rail 20A. Since the front wall 58 is located below the inclined portion 34A of the side rail 20A, it is not joined to the side rail 20A.

  Further, as shown in FIG. 5, the bottom wall 54, the front wall 58, and the rear wall 60 of the bracket body 50 are joined to the end of the second cross member lower 24B. That is, the front bracket 14 </ b> A is directly joined to the second cross member 24. As shown in FIGS. 4A and 5, a portion where the front wall 58 is joined to the second cross member lower 24 </ b> B, where a stress is concentrated when a load is input from the lower arm, is referred to as a welded portion W <b> 1.

  Further, as shown in FIG. 4A, the vehicle width direction inner end 63 of the front wall 58 is folded back toward the vehicle and overlaps the inner wall 56, and is joined by arc welding (welded portion W2). ing.

  On the other hand, the upper plate 52 is joined to the top surface 80A of the side rail upper 28A and to the flange portions 59 and 61 located at the upper end portions of the front wall 58 and the rear wall 60 of the front bracket 14A.

  Further, as shown in FIGS. 1 to 3, a rear bracket 16A is attached to the front end side of the outer inclined portion in the horizontal portion 36A of the side rail 20A.

  As shown in FIGS. 6 and 9, the rear bracket 16 </ b> A includes a bracket body 64 that pivotally supports the rear side of the lower arm, and a patch 66 attached to the lower side of the bracket body 64.

  As shown in FIGS. 6 and 7, the bracket main body 64 is curved upward from the upper portion of the top surface 80A of the side rail upper 28A toward the vehicle width direction outside, and thereafter, the upper wall 68 extending horizontally. , A front wall 70 extending downward from the vehicle front end of the upper wall 68, and a rear wall 72 extending downward from the vehicle rear end of the upper wall 68.

  The front wall 70 and the rear wall 72 are provided with holes 74, respectively. The lower arm is supported by the rear bracket 16A by inserting and pinning the pin of the lower arm between the holes 74, 74.

  As shown in FIG. 6, the bracket body 64 is formed with a flange portion 76 bent from the lower end of the front wall 70 toward the front of the vehicle, and as shown in FIG. A flange portion 78 bent toward the rear of the vehicle is formed. Each of the flange portions 76 and 78 extends inward in the vehicle width direction, and extends to a lower side of the side rail 20A (side rail lower 30A).

  As shown in FIGS. 6 and 7, the front wall 70 and the rear wall 72 are joined to the side rail upper 28A by arc welding from the top surface 80A to the vertical wall portion 82A (FIGS. 6, 7, (See welds W3 and W4). As shown in FIG. 8, the vehicle width direction inner ends of the flange portions 76 and 78 are joined to the side rail lower 30A (see FIG. 8, welded portions W5 and W6).

  A flat patch 66 is attached between the flange portions 76 and 78 of the bracket body 64. That is, as shown in FIG. 8, the front side of the patch 66 on the vehicle is the flange portion 76 of the bracket body 64, the rear side of the vehicle is the flange portion 78, and the inner end in the vehicle width direction is the top surface 84A of the side rail lower 30A. The patch 66 is fixed to the side rail 20A and to the bracket main body 64 by being joined (see FIG. 8, welded portions W7 to W9).

  When the rear bracket 16A is attached to the side rail 20A by arc welding, as shown in FIG. 10, the rear bracket 16A is attached to the side rail 20A using the torch 86 before the engine mounting bracket 31A is attached to the side rail 20A. To join.

  When the welds W3 and W4 are formed by arc welding, as shown in FIG. 11, first, the torch 86 is moved in the horizontal direction while the suspension member 12 is held in the horizontal direction (FIG. 11). (See arrow A) Arc welding is performed on the top surface 80A side. Next, the suspension member 12 is rotated 90 degrees (see the arrow B in FIG. 11) to hold the suspension member 12 in the vertical direction, and the torch 86 is moved in the horizontal direction (the arrow shown in the vertical direction in FIG. 11). C) to weld the vertical wall portion 82A side.

(Comparative example)
A lower body structure according to a comparative example, which will be referred to for describing an operation of the lower body structure 10 according to the present embodiment described later, will be described. In the lower vehicle body structure according to the comparative example, the same components as those of the lower vehicle body structure according to the present embodiment are denoted by the same reference numerals as those obtained by adding 100, and detailed description thereof is omitted.

  As shown in FIG. 12A, the lower body structure 200 according to the first comparative example is different from the lower body structure 10 only in the structure of the front brackets 114A and 114B. Specifically, as shown in FIG. 12A, an opening 202 extending from the upper end to the lower end is formed between the front wall 158 and the inner wall 156.

  As shown in FIG. 13A, the underbody structure 300 according to the second comparative example is different from the underbody structure 10 only in the structure of the side rails 120A, 120B and the rear brackets 116A (116B). It is. That is, the cross-sectional area (cross-sectional height) of the side rail 120A is larger than that of the side rail 20A shown in FIG. As a result, the positions of the holes 174 and 174 formed in the front wall 170 and the rear wall 172 of the rear bracket 116A attached to the horizontal portion 136A of the side rail 120A are lower than the top surface 180A of the side rail upper 128A. positioned.

The operation of the vehicle body lower structure 10 thus configured will be described.
As shown in FIGS. 1 and 2, when a load is input to the suspension member 12 from the lower arm via the front bracket 14A and the rear bracket 16A, the side rail 20A is attached to the side rail 20A at the mounting position of the front bracket 14A. The second cross member 24 is bridged between the side rails 20B. In addition, the second cross member 24 and the front bracket 14A are directly joined.

  Therefore, the load input from the lower arm to the suspension member 12 via the front bracket 14A is transmitted to the side rail 20A and also to the second cross member 24, and the second cross member 24 and the front bracket 14A Is suppressed from being concentrated on the joint portion (welded portion W1) and the like. As a result, the deformation of the suspension member 12, particularly the side rail 20A, due to the load input from the lower arm is suppressed.

  Further, the rack housing 40 of the EPS 18 arranged in parallel with the second cross member 24 by being fastened to the mounting portions 38A, 38B of the third cross member 26, allows the second cross member 24 to be substantially at the center in the vehicle width direction. Has been concluded. As described above, the rigidity of the second cross member 24 can be improved by fastening the EPS 18 fixed between the mounting portions 38A and 38B to the second cross member 24. That is, deformation of the suspension member 12 due to a load input from the lower arm can be further suppressed.

  In order to suppress the deformation of the side rail 20A, it is conceivable to improve the rigidity of the side rail 20A. For example, an increase in the cross-sectional area and an increase in the plate thickness of the side rail 20A. However, an increase in the cross-sectional area of the side rail 20 </ b> A has a disadvantage that the installation space for the members arranged on the suspension member 12 is reduced. In addition, the increase in the thickness of the side rails 20A further reduces the formability of the side rails 20A and increases the weight more than the additional weight by adding the second cross member 24.

  In this regard, the underbody structure 10 is as follows. By disposing the second cross member 24 and attaching the existing EPS 18 to the second cross member 24, the rigidity of the suspension member 12 can be increased without impairing the formability of the suspension member 12 and without excessively increasing the weight. Can be improved.

  The load input from the lower arm to the rear bracket 16A is supported by the first cross member 22, so that the deformation of the side rail 20A is suppressed.

  Next, the operation of the front bracket 14A will be described in comparison with the vehicle body lower structure 200 according to the first comparative example.

  That is, when a load is input from the lower arm to the front bracket 114A of the vehicle body lower structure 200 according to the first comparative example, as shown in FIG. 12B, the joint between the front wall 158 and the second cross member 124 is formed. The stress concentrates on the (welded portion W1), and the welded portion W1 is largely out of plane. As a result, the front wall 158 not joined to the side rail 120A is separated from the inner wall 156 joined to the side rail 120A, and the opening 202 is enlarged. That is, the front bracket 114A is greatly deformed by the load input from the lower arm.

  On the other hand, as shown in FIG. 4A, the front bracket 14A according to the present embodiment bends the inner end 63 of the front wall 58 in the vehicle width direction toward the vehicle rear side and overlaps the inner wall 56. , And arc welding (welded portion W2). That is, the front bracket 14A has the opening 202 formed by joining the front wall 58 joined only to the second cross member 24 to the inner wall 56 joined to the side rail 20A. The rigidity of the front wall 58 can be improved as compared with the front side bracket 114A.

  Therefore, as shown in FIG. 4B, when a load is input to the front bracket 14A from the lower arm, stress acting on the welded portion W1 between the front bracket 14A and the second cross member 24 is suppressed, and the front side Deformation of the bracket 14A is suppressed. As a result, the durability of the front bracket 14A is also improved.

  Next, the operation of the rear bracket 16A will be described in comparison with the vehicle body lower structure 300 according to the second comparative example.

  As shown in FIG. 13B, a side rail 20A to which the rear bracket 16A is attached is a side rail 120A according to the second comparative example at a rear end horizontal portion 36A (see FIG. 13A). The cross-sectional area (height) is reduced as compared with. This is because the arrangement space was reduced in response to an increase in the size of the differential unit provided above the side rail 20A.

  That is, as shown in FIG. 13 (B), (the centers of) the holes 74, 74 of the rear bracket 16A are positioned higher than the top surface 80A of the side rail upper 28A. Therefore, as shown in FIG. 9, when a load F in the vehicle width direction is input to the rear bracket 16A from the lower arm, a counterclockwise rotational moment in the figure that crushes the side rail upper 28A is generated. Acts on the side rail 20A. Here, since the cross-sectional area of the side rail 20A is smaller than that of the side rail 120A of the second comparative example, the rigidity of the side rail 20A is lower than that of the side rail 120A. However, since the welded portions W3 and W4 on which a high stress acts when a load is input from the lower arm extend from the top surface 80A of the side rail upper 28A to the vertical wall portion 82A, that is, the area of the welded portions W3 and W4 is reduced. Due to the increase, the rigidity of the welded portions W3 and W4 is improved. As a result, the stress acting on the welds W3 and W4 is suppressed. Therefore, the input height of the load F (the height of the hole 74) to the rear bracket 16A is higher than the top surface 80A of the side rail 20A, and the cross-sectional area of the side rail 20A is smaller than the cross-sectional area of the side rail 120A. Also, as shown in FIG. 14, when the load F is input to the rear bracket 16A from the lower arm, the deformation of the side rail 20A (the side rail upper 28A) is suppressed.

  The bracket body 64 is joined to the side rail upper 28A at the welds W3 and W4, and is joined to the side rail lower 30A at the welds W5 and W6. Further, on the side opposite to the upper wall 68 side of the bracket body 64, a patch 66 is joined between the flange portions 76 and 78 at welded portions W7 to W9. Accordingly, the rigidity of the rear bracket 16A increases, and when a load is input from the lower arm to the rear bracket 16A, the deformation of the side rail 20A is further suppressed.

  Since the welded portions W3 and W4, which are the joining portions between the rear bracket 16A and the side rail upper 28A, extend from the top surface 80A of the side rail upper 28A to the vertical wall portion 82A, the top surface 80A is welded. Then, the suspension member 12 is held in a horizontal state by a jig (not shown), and the torch 86 is moved in the horizontal direction (see the arrow A in FIG. 11) and welded. Thereafter, the suspension member 12 is rotated 90 degrees by a jig (see the arrow B in FIG. 11), the vertical wall portion 82A is kept horizontal, and the torch 86 is horizontally moved (in FIG. 11, the vertical direction is shown). (See arrow C) and weld. That is, when welding the welded portions W3 and W4 on the side of the vertical wall portion 82A, the vertical wall portion 82A is set in a horizontal state to prevent dripping of the arc and enable welding.

  Further, during the manufacturing of the vehicle body lower part structure 10, before the welding of the welded portions W3 and W4, the engine mounting bracket 31A is not attached to the side rail 20A as shown in FIG. The degree of freedom of movement is improved, and welding of the welded portions W3 and W4 (vertical wall portion 82A) becomes easy.

  In addition, in the vehicle body lower part structure 10 of this embodiment, although the structure provided with the 1st cross member 22, the 2nd cross member 24, and the 3rd cross member 26, the structure which omitted the 3rd cross member 26 may be sufficient.

  Further, in the present embodiment, the rack housing 40 of the EPS 18 is arranged along the longitudinal direction of the second cross member 24 by being attached to the attaching portions 38A, 38B, but is not limited to this. Absent. That is, the rack housing 40 may have another configuration as long as it is fixed to a member on the vehicle body side other than the second cross member 24 and is arranged along the longitudinal direction of the second cross member 24. Alternatively, the rack housing 40 may be attached to the second cross member 24 itself at a plurality of different positions in the vehicle width direction.

  In addition, the present invention can be variously modified and implemented without departing from the gist thereof. In addition, it goes without saying that the scope of rights of the present invention is not limited to the above embodiment.

10 Body lower structure 14A, 14B Front lower arm mounting bracket (front lower arm mounting part)
16A, 16B Rear lower arm mounting bracket (Rear lower arm mounting part)
18 Electric power steering device 20A, 20B Side rail 22 First cross member 24 Second cross member 40 Rack housing

Claims (1)

A pair of side rails extending in the vehicle front-rear direction and spaced apart in the vehicle width direction;
A front lower arm mounting portion that is disposed at an intermediate portion between a front end portion and a rear end portion of each of the side rails in a vehicle front-rear direction and to which a lower arm supporting a suspension is mounted;
A rear lower arm mounting portion that is disposed on the rear end side of the front lower arm mounting portion in each side rail and to which the lower arm is mounted;
A first cross member bridged between the pair of side rails at the rear end side of the side rail at a position closer to the rear end than the mounting position of the front lower arm mounting portion;
A second cross member bridged between the pair of side rails along the first cross member at a mounting position of the front lower arm mounting portion of the side rail;
An electric power steering device in which a rack housing disposed along a longitudinal direction of the second cross member is attached to the second cross member;
Wherein the front lower arm mounting portion includes a front wall joined to the second cross member, and an inner wall joined to the side rail, and an end of the front wall bent rearward of the vehicle. The lower body structure of the vehicle body is overlapped with and joined to the inner wall .

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