JP3849575B2 - Subframe mounting structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sub-frame mounting structure for a vehicle body, and more particularly to an improvement in a mounting structure for a sub-frame disposed below a side member extending in the front-rear direction of the vehicle body.
[0002]
[Prior art]
Conventionally, a side member extending in the front-rear direction of the vehicle body is provided as a component constituting the front skeleton structure of the vehicle body.
[0003]
A subframe extending in the longitudinal direction of the vehicle body along the side member is also disposed below the side member in order to support a suspension arm and the like.
[0004]
The subframe is attached to the side member via a subframe mounting bracket (hereinafter, abbreviated as a mounting bracket as appropriate) formed by forming a plate-shaped steel material. For example, those disclosed in Japanese Patent Application Laid-Open No. 4-169379 are known.
[0005]
This subframe mounting structure forms a closed cross section by a mounting bracket formed with a vertical wall and a horizontal wall having a substantially L-shaped cross section and a part of the outer peripheral wall of the side member. In addition, a sub-frame mounting nut that is connected to the vertical wall and the horizontal wall by spot welding and divides the closed cross-sectional area into two closed cross-sectional areas, and is further fixed to the horizontal wall and the re-force. It is provided.
[0006]
According to the subframe mounting structure configured as described above, the rigidity of the subframe mounting structure can be improved without increasing the weight.
[0007]
[Problems to be solved by the invention]
By the way, when reducing the above-described subframe mounting structure, it is conceivable to change the mounting bracket from a steel material to a lighter aluminum material.
[0008]
However, since aluminum materials have higher thermal conductivity and lower electrical resistance than steel materials, a spot gun that spot welds this aluminum material will flow a larger current than a steel material. It is necessary to use one corresponding to.
[0009]
However, since the spot gun corresponding to such a large current increases in size, it requires a larger space in the spot welding process, and the size of the flange for joining the spot weld is also increased. It needs to be bigger.
[0010]
And when a joining flange is enlarged in this way, an increase in weight is caused and the original purpose of weight reduction cannot be realized.
[0011]
In view of this, it is conceivable to perform joining by arc welding that does not require a joining flange, instead of spot welding.
[0012]
However, in joining by arc welding, there is a possibility that the mounting bracket may be deformed by welding heat, and when this deformation occurs, a work for correcting the deformation must be separately performed in a later process, resulting in an increase in work man-hours. It will be.
[0013]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a subframe mounting structure that can be reduced in weight without causing deformation.
[0014]
[Means for Solving the Problems]
In order to solve the above-described problem, a subframe mounting structure according to claim 1 of the present invention is configured such that a subframe provided below a side member extending in the front-rear direction of the vehicle body is attached to the side member via a subframe mounting bracket. A sub-frame mounting structure for mounting, wherein the sub-frame mounting bracket includes an upper wall surface bonded to the lower surface of the side member, a lower wall surface bonded to the upper surface of the sub frame, the upper wall surface, and the lower wall surface. An intermediate wall surface provided between the upper wall surface and the lower wall surface, wherein the upper wall portion and the lower wall portion open in opposite directions across the intermediate wall surface, and The intermediate wall surface has a die-cutting gradient so that it can be punched with respect to the direction of the opening with respect to the upper portion and the direction of the opening with respect to the lower portion. And wherein the door.
[0015]
Here, the upper part and the lower part open in opposite directions across the intermediate wall surface. For example, when the upper opening is directed toward the rear of the vehicle body, the lower opening is the vehicle body. For example, when the opening on the upper side is directed to the right side of the vehicle body, it means that the opening on the lower side is formed to face the left side of the vehicle body.
[0016]
The upper wall, the intermediate wall, and the lower wall as a whole are formed so that the cross section thereof becomes, for example, a substantially “self” shape, a substantially “5” shape, a substantially “Z” shape, or the like.
[0017]
According to the subframe mounting structure according to claim 1 configured as described above, since the subframe mounting bracket can be integrally formed by casting as a whole, the plate-shaped member is bent and then spotted. Rigidity can be improved compared to the welded and joined subframe mounting bracket.
[0018]
The intermediate wall also acts as a reinforcing member in the same way as the reinforcement of the conventional subframe mounting bracket. However, since this reinforcement (intermediate wall) is not joined by spot welding as in the prior art, for example, an aluminum alloy is used. Unlike light alloy materials such as steel, there is no need to perform spot welding using a spot gun that can handle large currents, and there is no need to join by arc welding or the like. There is no deformation.
[0019]
And weight reduction can be attained by forming with light alloy materials, such as an aluminum alloy material, for example.
[0020]
In addition, the subframe mounting bracket has a hollow shape with a hollow inside, so it is lighter than a solid block product. The hollow shape is molded by a die-cut structure for casting. In this case, since the opening directions are opposite to each other in the upper part and the lower part, the relationship between the upper wall and the lower wall even if the upper part and the lower part are formed with a die-cutting gradient in each opening. Then, it is possible to substantially cancel the inclination angle of the die-drawing gradient provided in each, and it is possible to form the upper wall and the lower wall substantially in parallel without performing secondary processing such as machining. .
[0021]
As a result, it is possible to easily set the lower surface of the side member and the upper surface of the subframe substantially in parallel without performing the secondary processing, thereby reducing the number of work steps and facilitating the mounting work. be able to.
[0022]
In the subframe mounting structure according to claim 2 of the present invention, an upper vertical wall that joins the upper wall and the intermediate wall and a lower vertical wall that joins the intermediate wall and the lower wall are formed. The sub-frame mounting structure according to claim 1 is characterized.
[0023]
According to the subframe mounting structure according to claim 2 configured as described above, the external force input from the subframe to the lower wall of the subframe mounting bracket is a vertical wall (vertical rib) formed in the lower opening. ) Is distributed to the intermediate wall, and further distributed from the intermediate wall to the vertical wall (vertical rib) formed in the opening on the upper side and transmitted to the upper wall, and input from the upper wall to the side member. Therefore, the input external force can be widely dispersed, and the attachment surface of the subframe and the attachment surface of the side member can be prevented from being deformed due to concentration of the external force.
[0024]
Of course, since each vertical wall also functions as a rib, the rigidity of the subframe mounting bracket itself can be increased.
[0025]
Further, the sub-frame mounting structure according to claim 3 of the present invention extends in the vertical direction and has upper and lower ends joined to the intermediate wall and the lower wall, respectively, and at least one of the peripheral surfaces between the upper and lower ends. A boss is formed by supporting the other frame on the wall surface, and a female thread portion is formed on the shaft central portion of the boss, and the mounting bolt for attaching the subframe is screwed upward from the lower surface side of the lower wall. The subframe mounting structure according to claim 1 or 2 is provided.
[0026]
According to the sub-frame mounting structure according to claim 3 configured as described above, since the upper end of the boss is joined to the intermediate wall and the lower end is joined to the lower wall, the opening on the lower side of the sub-frame mounting bracket The rigidity of can be further increased.
[0027]
In addition, since the boss is supported not only by the upper and lower ends but also the peripheral surface between the upper and lower ends by other wall surfaces, the support rigidity of the boss is improved, and when a compressive force is applied in the vertical direction, the upper and lower ends It can suppress that the part between these is bent and shaken.
[0028]
The other wall surface is, for example, a peripheral wall formed on the side opposite to the opening direction of the opening, or the vertical wall when applied to the subframe mounting structure according to claim 2.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of a subframe mounting structure according to the present invention will be described with reference to the drawings.
[0030]
A subframe attachment structure 100 according to the present embodiment shown in FIG. 1 is a structure in which a subframe assembly 40 is attached to a side member 30 that is a front skeleton structure of a vehicle body via a subframe attachment bracket 10.
[0031]
Here, the side member 30 is formed of an extruded material.
[0032]
The subframe assembly 40 includes a first subframe 41 extending in the front-rear direction of the vehicle body along the lower side of the side member 30, and a left and right side member 30 (the left side member is not shown) extending in the vehicle width direction. ) And a connecting portion 43 that connects the first subframe 41 and the second subframe 42 at their end portions.
[0033]
The subframe mounting bracket 10 is a cast product made of an aluminum alloy, and as shown in the cross-sectional view of FIG. 2, the upper surface 11a of the upper wall 11 is joined to the lower surface 32 of the side member 30 by arc welding, The lower surface 12 a of the lower wall 12 is joined to the upper surface 44 of the connecting portion 43 of the subframe assembly 40, and the subframe assembly 40 is attached to the side member 30.
[0034]
Here, reference numeral 60 represents a weld bead formed by arc welding.
[0035]
Further, the upper surface 11 a of the upper wall 11 of the subframe mounting bracket 10 and the lower surface 12 a of the lower wall 12 are formed substantially parallel to each other, and an intermediate wall 13 is formed between the upper wall 11 and the lower wall 12. Yes.
[0036]
Further, side walls 16 and 17 are formed to connect both side edges of the upper wall 11, the lower wall 12 and the intermediate wall 13, and in the upper part across the intermediate wall 13, the rear side (opposite to the arrow F direction) is directed. A front wall 14 that constitutes an end surface on the front side of the vehicle body is formed so as to open, and an end surface on the rear side of the vehicle body is configured to open toward the front (in the direction of arrow F) in the lower part across the intermediate wall 13. A rear wall 15 is formed.
[0037]
An upper vertical rib 18 that is a vertical wall connected to the upper wall 11 and the intermediate wall 13 is formed in an opening 21 (hereinafter referred to as an upper opening) 21 above the intermediate wall 13, and the lower opening is formed. A lower vertical rib 19 which is a vertical wall connected to the lower wall 12 and the intermediate wall 13 is formed in the portion (hereinafter referred to as a lower opening) 22.
[0038]
Further, at the innermost part of the lower opening 22, the upper end is connected to the lower surface of the intermediate wall 13, the lower end is connected to the upper surface of the lower wall 12, and the lower vertical rib 19 and the rear wall 15 are integrated with the peripheral surface. A substantially semi-cylindrical boss 20 is formed which extends in the vertical direction.
[0039]
A female screw 23 is formed at the axial center of the boss 20. Specifically, the female screw 23 has a washer 51 attached to the connecting portion 43 of the subframe assembly 40 upward from the lower surface side of the lower wall 12. The mounting bolts 50 inserted through are formed so as to be screwed together.
[0040]
The subframe mounting bracket 10 having the above-described shape is formed by the first mold 71 and the second mold 72 shown in FIG.
[0041]
That is, a molten aluminum alloy material is cast into a space formed between the first mold 71 and the second mold 72 and is cut after curing, but the first mold 71 is mold in the direction of arrow P. The second mold 72 is punched in the P ′ direction opposite to the arrow P.
[0042]
For this reason, on the upper surface side and the lower surface side of the upper wall 11, a mold cutting gradient for enabling the first mold 71 to be punched in the direction of arrow P is formed by (½) θ ₁ .
[0043]
Similarly, the lower wall 72 is formed with (1/2) θ _{2 on} each of the upper side and the lower side so that the second mold 72 can be punched in the direction of the arrow P ′. .
[0044]
Further, a die draft angle θ ₃ is also formed on the upper surface side of the intermediate wall so that the mold forming the upper opening 21 is removed, and the intermediate wall is formed so that the mold forming the lower opening 22 is removed. A die cutting angle θ ₄ is also formed on the lower surface side.
[0045]
Note that the die draft angle θ ₃ is larger than the die draft angle (1/2) θ ₁ (θ ₃ > (1/2) θ ₁ ), and the die draft angle θ ₄ is the die draft angle ( 1/2) larger than θ ₂ (θ ₄ > (1/2) θ ₂ ).
[0046]
As described above, by setting the die-cutting gradient angles θ ₃ and θ ₄ of the intermediate wall 13 portion where the first mold 71 and the second mold 72 are opposed to each other, the die-cutting can be performed more easily.
[0047]
Further, the die-cutting gradient angles θ ₁ and θ ₂ are substantially equal (θ ₁ ≈θ ₂ ), and therefore, the upper surface of the upper wall 11 and the lower surface of the lower wall 12 are later subjected to secondary processing such as machining. There is no parallel.
[0048]
Further, the rear wall 15 is formed with a semi-conical protrusion 24 that protrudes rearward in a semi-conical shape and functions as a part of a seat with which the upper surface 44 of the connecting portion 43 abuts.
[0049]
Next, the operation of the subframe mounting structure 100 according to this embodiment will be described.
[0050]
First, since the entire subframe mounting bracket 10 used in the subframe mounting structure 100 is integrally formed by casting, a thin plate-like member is bent and formed as in the prior art. Rigidity is improved compared to spot-welded subframe mounting brackets.
[0051]
Therefore, the strength against an external force such as a push-up force input from the subframe assembly 40 is higher than that of the conventional one.
[0052]
Moreover, since the sub-frame mounting bracket 10 has a hollow shape in which the interior is hollowed out, it is lighter than a solid one.
[0053]
When such a hollow shape is formed by a die-cutting structure for casting, it is necessary to form a gradient angle for die-cutting, but the subframe mounting bracket 10 in the present embodiment has the intermediate wall 13 Since the opening direction of the upper opening 21 and the opening direction of the lower opening 22 are opposite to each other, even if the respective die cutting gradients are formed in the upper opening 21 and the lower opening 22, As shown in FIG. 3, the relationship between the upper surface 11a of the upper wall 11 and the lower surface 12a of the lower wall 12 is such that the die-cutting gradient angles (1/2) θ ₁ , (1/2) θ ₂ provided on each of them are Substantially cancels out to be in a substantially parallel state.
[0054]
Therefore, it is not necessary to perform secondary processing such as cutting on the upper surface 11a of the upper wall 11 and the lower surface 12a of the lower wall 12.
[0055]
As a result, it is possible to reduce the number of work steps and facilitate the mounting work.
[0056]
The intermediate wall 13 also functions as a reinforcement for improving the strength of the outer peripheral wall of the sub-frame mounting bracket 10, but is different from the conventional one in which a separate reinforcement is joined by spot welding. In contrast, because it is integrally formed by casting, it is not necessary to perform spot welding using a spot gun that supports a large current corresponding to an aluminum alloy material, and it is also necessary to join a reinforcement by arc welding or the like. Therefore, the reinforcement is not deformed by the high heat of arc welding.
[0057]
Therefore, it is possible to prevent the conventional deformation from occurring even though the aluminum alloy material is used as a lightweight member.
[0058]
Further, the upper vertical rib 18 joined to the upper wall 11 and the intermediate wall 13 and the lower vertical rib 19 connected to the intermediate wall 13 and the lower wall 12 make the subframe mounting bracket 10 particularly rigid in the vertical direction. improves.
[0059]
That is, the external force input from the subframe assembly 40 to the lower wall 12 of the subframe mounting bracket 10 is distributed not only to the side walls 16 and 17 but also to the lower vertical rib 19.
[0060]
As a result, the strength can be improved as compared with the case where the lower vertical rib 19 is not formed.
[0061]
Similarly, the external force transmitted to the intermediate wall 13 is distributed not only to the side walls 16 and 17 but also to the upper vertical rib 18.
[0062]
Therefore, the strength can be improved as compared with the case where the upper vertical rib 18 is not formed.
[0063]
And it can prevent that the lower surface 32 which is the attachment surface of the sub-frames 41 and 42 and the attachment surface at the side member 30 side deform | transforms by the concentration of an external force.
[0064]
In addition, the boss 20 into which the mounting bolt 50 is screwed is not disposed over the entire height between the upper wall 11 and the lower wall 12 of the subframe mounting bracket 10, but the lower wall 12. Since it is formed only within the height range from the intermediate wall 13 to the intermediate wall 13, the formation length is short, and even when a compressive force is applied in the vertical direction, bending on the peripheral surface is unlikely to occur.
[0065]
As a result, the mounting bolt 50 can be stably screwed.
[0066]
Furthermore, since the upper end of the boss 20 is joined to the intermediate wall 13 and the lower end is joined to the lower wall 12, the rigidity of the lower opening 22 of the subframe mounting bracket can be further increased.
[0067]
Further, the boss 20 is simply joined at the upper end to the intermediate wall 13 and the lower end is joined to the lower wall 12, and the middle is not supported at all, and the middle part also has the lower vertical rib 19 and the rear wall 15. Therefore, when the compressive force is applied in the vertical direction, the portion between the upper and lower ends can be prevented from bending and swinging.
As described above, the subframe mounting structure 100 according to the present embodiment can achieve weight reduction while preventing the side member 30, the subframe assembly 40, and the subframe mounting bracket 10 from being deformed.
[0068]
[Modification 1]
The subframe mounting structure 100 shown in FIG. 4 is inclined so that the upper side of the front wall 14 of the subframe mounting bracket 10 in the subframe mounting structure 100 shown in FIGS. It is the modification 1.
[0069]
According to the subframe mounting structure 100 of the modification 1 configured as described above, the same operations and effects as the subframe mounting structure 100 according to the embodiment described above are exhibited.
[0070]
Further, in the first modification, the external force transmitted from the subframe assembly 40 to the intermediate wall 13 is more easily transmitted to the front wall 14, and the external force is transmitted to the side walls 16 and 17 (see FIG. 2), the upper vertical ribs 18 and The degree of dispersion on the front wall 14 can be made more uniform, and the rigidity and strength of the subframe mounting bracket 10 can be improved.
[0071]
[Modification 2]
The subframe mounting structure 100 shown in FIG. 5 increases the die-cutting gradient angles θ ₃ and θ ₄ of the intermediate wall 13 of the subframe mounting bracket 10 in the subframe mounting structure 100 shown in FIGS. 14 and the rear wall 15 are integrated with the intermediate wall 13 so that the longitudinal sections of the upper wall 11, the intermediate wall 13 and the lower wall 12 are formed in a substantially “Z” shape as a whole.
[0072]
According to the subframe mounting structure 100 of the second modification configured as described above, the same operations and effects as the subframe mounting structure 100 according to the above-described embodiment are exhibited.
[0073]
Furthermore, in the second modification, since the die-cutting gradient angles θ ₃ and θ _{4 of} the intermediate wall 13 are large, it is easy to perform mold parting and the volume is reduced, so that the amount of material used can be reduced. Manufacturing cost can be reduced.
[0074]
【The invention's effect】
As described above, according to the subframe mounting structure according to claim 1 of the present invention, the subframe mounting bracket can be integrally formed by casting as a whole. Furthermore, the rigidity can be improved as compared with the subframe mounting bracket that is spot welded.
[0075]
The intermediate wall also acts as a reinforcing member in the same way as the reinforcement of the conventional subframe mounting bracket. However, since this reinforcement (intermediate wall) is not joined by spot welding as in the prior art, for example, an aluminum alloy is used. Unlike light alloy materials such as metal, there is no need to perform spot welding using a spot gun that can handle large currents, and there is no need to join by arc welding or the like. The intermediate wall in the present invention is not deformed.
[0076]
And weight reduction can be achieved by forming with light alloy materials, such as an aluminum alloy material.
[0077]
In addition, the subframe mounting bracket has a hollow shape with a hollow inside, so it is lighter than a solid block product. The hollow shape is molded by a die-cut structure for casting. In this case, since the opening directions are opposite to each other in the upper part and the lower part, the relationship between the upper wall and the lower wall even if the upper part and the lower part are formed with a die-cutting gradient in each opening. Then, it is possible to substantially cancel the inclination angle of the die-drawing gradient provided in each, and it is possible to form the upper wall and the lower wall substantially in parallel without performing secondary processing such as machining. .
[0078]
As a result, it is possible to easily set the lower surface of the side member and the upper surface of the subframe substantially in parallel without performing the secondary processing, thereby reducing the number of work steps and facilitating the mounting work. be able to.
[0079]
According to the subframe mounting structure of the present invention, the external force input from the subframe to the lower wall of the subframe mounting bracket is a vertical wall (vertical rib) formed in the opening on the lower side. To be input to the intermediate wall, and further distributed from the intermediate wall to the vertical wall (vertical rib) formed in the opening on the upper side and transmitted to the upper wall, and input from the upper wall to the side member. The input external force can be widely dispersed, and the attachment surface of the subframe and the attachment surface of the side member can be prevented from being deformed due to concentration of the external force.
[0080]
Of course, since each vertical wall also functions as a rib, the rigidity of the subframe mounting bracket itself can be increased.
[0081]
According to the subframe mounting structure of the present invention, the upper end of the boss is joined to the intermediate wall and the lower end is joined to the lower wall. The rigidity can be further increased.
[0082]
In addition to the upper and lower ends of the boss, the peripheral surface between the upper and lower ends is also supported by other wall surfaces. Therefore, the support rigidity of the boss is improved, and when a compressive force is applied in the vertical direction, A practically beneficial effect is exhibited in that it is possible to suppress the bending and swinging of the portion between the two.
In addition, the same effect can be acquired also when the said vertical wall in the sub-frame mounting structure which concerns on Claim 2 is applied as another wall surface.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main part of a subframe mounting structure 100 according to an embodiment of the present invention.
2A is a cross-sectional view taken along line AA in FIG. 1. FIG. (B) It is sectional drawing by the BB line in FIG.
FIG. 3 is a cross-sectional view corresponding to FIG. 2 (a) for explaining the die removal action of the subframe mounting bracket from the mold.
FIG. 4 is a cross-sectional view corresponding to FIG.
FIG. 5 is a cross-sectional view corresponding to FIG.
[Explanation of symbols]
10 Subframe mounting bracket 11 Upper wall 11a Upper surface 12 Lower wall 12a Lower surface 13 Intermediate wall 14 Front wall 15 Rear wall 16, 17 Side wall 18 Upper vertical rib 19 Lower vertical rib 20 Boss 21 Upper opening 22 Lower opening 23 Female thread Portion 24 Semiconical protrusion 30 Side member 31 Upper surface 32 Lower surface 40 Subframe assembly 41 First subframe 42 Second subframe 43 Connecting portion 44 Upper surface 50 Mounting bolt 51 Washer 60 Weld bead 71 First mold 72 Second mold 100 Subframe Mounting structure F Front I Inner U Upper P Mold release direction of the first mold P ′ Mold release direction of the second mold θ _{1 to} θ ₄ Die release angle

Claims (3)

A subframe mounting structure for mounting a subframe provided below a side member extending in the front-rear direction of the vehicle body to the side member via a subframe mounting bracket,
The sub-frame mounting bracket includes an upper wall surface joined to the lower surface of the side member, a lower wall surface joined to the upper surface of the sub frame, and an intermediate wall surface provided between the upper wall surface and the lower wall surface. And the upper wall surface and the lower wall surface are formed substantially parallel to each other, and the upper portion and the lower portion are opened in opposite directions with the intermediate wall surface interposed therebetween, and the intermediate wall surface is formed with respect to the upper portion. A sub-frame mounting structure characterized by having a die-cutting gradient so as to be die-cut with respect to the direction of the opening and the direction of the opening of the lower portion. The upper vertical wall connected to the upper wall and the intermediate wall and the lower vertical wall connected to the intermediate wall and the lower wall are formed. Subframe mounting structure. The upper and lower ends are joined to the intermediate wall and the lower wall extending in the vertical direction, respectively, and at least a part of the peripheral surface between the upper and lower ends is formed with a boss formed by being supported by another wall surface, The internal thread part by which the attachment volt | bolt which attaches the said sub-frame to the axial center part of a boss | hub from the lower surface side of the said lower wall is screwed is provided. Subframe mounting structure.

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