JP2015186960A - Vehicle front body structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle front body structure capable of achieving both a reduction in vehicle weight and a reduction in road noise.SOLUTION: A vehicle front body structure comprises: a pair of right and left lower arms 23 rotatably supporting front wheels, respectively; a sub-frame 20 including a pair of right and left frame portions 21 swingably supporting the right and left lower arms 23 via support portions, respectively; an undercover member 30 fixed to the right and left frame portions 21 and covering a space between the right and left frame portions 21 from below; and a pair of right and left connecting members 15 connecting the right and left frame portions 21 to a torque box 8 and a floor frame 6, extension portions 15c extending inward in a vehicle width direction and connected to the undercover member 30 being formed in the right and left connecting members 15, respectively.

Description

  The present invention relates to a front body structure of a vehicle, and more particularly to a front body structure of a vehicle including a pair of left and right suspension arms and a subframe that supports the pair of left and right suspension arms.

Conventionally, various suspension mechanisms have been put to practical use for improving the ride comfort and handling stability of vehicles. In general, since the road surface followability is excellent, an independent suspension type suspension mechanism in which the left and right wheels can operate independently is employed.
Such an independent suspension type suspension mechanism includes a pair of left and right suspension arms that rotatably support a wheel, and a subframe that supports the pair of left and right suspension arms so as to be swingable. A pair of left and right frame portions that form a front support portion and a rear support portion of each suspension arm are provided.

A structure in which an under cover made of synthetic resin (for example, PP) for rectifying the air flow below the vehicle body is provided below the front part of the vehicle body for the purpose of improving the aerodynamic characteristics of the vehicle is well known.
The front body structure of a vehicle disclosed in Patent Document 1 includes a pair of left and right front side frames, a pair of left and right subframes connected to these front side frames and supporting a suspension, and below these subframes. An under cover that forms at least a part of the lower surface of the vehicle body, and a pair of left and right reinforcing members that are provided on the upper surface of the under cover and extend in the front-rear direction, are supported by the front side frame. ing.

JP 2009-286157 A

Since vehicle weight reduction is one of the most effective measures for improving vehicle fuel efficiency, in recent years, analysis tools such as CAE (Computer Aided Engineering) have been used to reduce the size of each part and frame members. Actively promoted.
In the case of a subframe, it is only necessary to secure the frame rigidity that can support the load input from the wheel via the suspension arm when the vehicle turns, and the thickness of the subframe can be reduced within the range that satisfies this load support function. It is possible to reduce the closed cross-sectional area.

However, when the thickness of the subframe is reduced by increasing the material strength, NVH (Noise Vibration Harshness) performance is deteriorated, which may affect the merchantability.
According to the CAE analysis, the inventor transmits the traveling vibration (load) input through the suspension arm to the subframe, and the sub vibration is generated by resonance of traveling vibration propagating in the subframe between the pair of left and right frames. It has been found that vibration of a predetermined frequency (for example, 30 to 200 Hz) occurs in the frame. This vibration of the sub-frame is transmitted from the front side frame to the vehicle interior, and is recognized as road noise that is uncomfortable for the passenger.

In the front vehicle body structure of a vehicle disclosed in Patent Document 1, the rigidity of the under cover is increased by the reinforcing member, and the rigidity of the vehicle body is increased by connecting the reinforcing member to the front side frame.
However, with this front vehicle body structure of the vehicle, it is not possible to suppress travel vibration propagating through the subframe, and it is not possible to reduce road noise transmitted to the vehicle interior.

  An object of the present invention is to provide a front vehicle body structure and the like of a vehicle that can achieve both vehicle body weight reduction and road noise reduction.

  The front body structure of the vehicle according to claim 1 is a pair of left and right suspension arms that rotatably support the front wheels, and a pair of left and right suspension arms that respectively support the left and right suspension arms so as to be swingable via a support portion. An under cover member that is fixed to the pair of left and right frames and covers a space between the pair of left and right frames from below; A pair of left and right connecting members that connect the pair of left and right frame portions to the vehicle body side member, and an extension portion that extends inward in the vehicle width direction and is connected to the under cover member. It is characterized by being formed respectively.

  In this vehicle front body structure, the traveling vibration (load) input from the suspension arm to the subframe is distributed to the vehicle body side member via the under cover member and the connecting member, so regardless of the thickness of the subframe. The vibration of the predetermined frequency generated in the subframe can be suppressed, and the road noise transmitted to the vehicle interior can be reduced.

According to a second aspect of the present invention, in the first aspect of the invention, each frame portion includes a front side support portion and a rear side support portion that support the suspension arm, and the vehicle body side fixing that is fixed to the vehicle body side member to each connection member. And a frame part side fixing part fixed to the one frame part, and the left and right frame part on an extension line connecting the vehicle body side fixing part and the extension part of either of the left and right connecting members. This is characterized in that a front support portion is set.
As a result, the front support portion and the vehicle body side fixed portion having a large input load are connected to each other in a diagonal straight line, so that the distance between the front support portion and the vehicle body side member can be minimized, and a predetermined frequency generated in the subframe Can be further suppressed.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, the vehicle body side fixing portion is fixed to a floor frame extending in the front-rear direction and a torque box connecting the floor frame and the side sill.
As a result, the input load is efficiently distributed to the floor frame and the torque box, so that vibration of a predetermined frequency that occurs in the subframe can be further suppressed.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the sub-frame includes a connecting portion that connects front ends of the pair of left and right frames, and cooperates with the under cover member. And a panel member forming a closed cross-sectional portion connecting the rear ends of the pair of left and right frame portions.
According to this, since the movement of the rear ends of the pair of left and right frame portions is restricted, vibrations of a predetermined frequency that occur in the subframe can be further suppressed.

  According to the front vehicle body structure of the vehicle of the present invention, both vehicle body weight reduction and road noise reduction can be achieved.

It is a bottom view of the front body structure of the vehicle according to the present embodiment. It is a left side view of FIG. FIG. 2 is a perspective view of a main part on the left side of FIG. 1. FIG. 3 is a left side perspective view of a front wheel suspension. It is a disassembled perspective view of a subframe, an undercover member, and a connection member. It is the VI-VI sectional view taken on the line of FIG. It is a perspective view of a connection member.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The following description merely exemplifies the present invention and does not limit the present invention, its application, or its use.

In this embodiment, an example in which the present invention is applied to a front vehicle body structure of a vehicle V whose drive system is a front engine rear drive (FR) type will be described.
As shown in FIG. 6, the engine 1 is arranged vertically in the engine room E, and a transmission 2 is connected to the rear part thereof. The rear end portion of the transmission 2 is disposed below the floor tunnel portion.

First, main members of the vehicle V will be described.
As shown in FIGS. 1 and 2, a dash lower panel 4 that partitions the engine room E and the vehicle compartment C in the front-rear direction is provided. The dash lower panel 4 includes a vertical wall portion 4a that extends in the vertical direction and supports the rear end portions of the pair of left and right front side frames 3, and a slant portion that inclines from the lower portion of the vertical wall portion 4a to a front height and a rear low shape. 4b, and a floor panel 5 extending substantially horizontally toward the rear of the vehicle is connected to the rear of the lower end of the slant portion 4b. In the figure, the arrow F indicates the front and the arrow L indicates the left.

  A pair of left and right side sills 7 extending in the front-rear direction having a closed cross-sectional shape are connected to the left and right ends of the floor panel 5, respectively. A pair of left and right floor frames 6 are provided which form a closed cross section extending in the front-rear direction in cooperation with the lower surface of the floor panel 5 on the inner side in the vehicle width direction than the pair of left and right side sills 7. The front end portion of the side sill 7 and the front end portion of the floor frame 6 adjacent to the side sill 7 are connected by a torque box 8 that forms a closed cross section extending in the vehicle width direction in cooperation with the floor panel 5. As a result, a pair of left and right closed substantially continuous cross sections can be formed in the left and right regions of the floor panel 5, respectively, thereby improving the rigidity of the lower vehicle body.

  A kick-up portion frame 10 that connects the rear end portion of the front side frame 3 and the front end portion of the floor frame 6 is joined and fixed to the front lower portion of the slant portion 4 b of the dash lower panel 4. A closed cross section is formed between the lower panel 4 and the lower panel 4. A subframe mounting base 16 is joined and fixed to the front lower portion of the kick-up portion frame 10. The sub-frame mounting base 16 includes three members: a mounting base outer, a mounting base inner, and a mounting base lower, and a closed cross section is formed between the sub-frame mounting base 16 and the kick-up unit frame 10. The sub-frame mounting rigidity is improved.

  The pair of left and right front side frames 3 linearly extend forward from the vertical wall portion 4a, and the front side frame inner and the front side frame outer cooperate to form a cross-section orthogonal to the front-rear direction in a cross shape. . As shown in FIG. 2, a suspension tower 11 is provided on the front side frame 3 in the middle in the front-rear direction and on the outer side in the vehicle width direction via front and rear legs 11a and 11b.

Next, the front wheel suspension mechanism will be described.
As shown in FIGS. 1 to 6, the sub-frame 20 of the front wheel suspension (wishbone suspension) is disposed in the lower part of the engine room E.
The sub-frame 20 is formed of a substantially U-shaped closed cross-section member that opens to the rear side in a plan view, and a pair of left and right sides in which the front support portion 21a and the rear support portion 21b of each lower arm 23 are formed. A frame portion 21 and a connecting portion 22 that connects the pair of left and right frame portions 21 with their front ends in the vehicle width direction are provided. A space between the pair of left and right frame portions 21 is covered by an under cover member 30 from below. Since the front wheel suspension has a symmetrical structure, the left front wheel suspension will be mainly described below.

As shown in FIG. 2, the upper end portion of the tower portion 12 erected on the outer side in the vehicle width direction of the frame portion 21 is fastened and fixed to the lower surface portion of the front side frame 3 at a position corresponding to the suspension tower portion 11. . As shown in FIGS. 1-3, the rear-end part of the frame part 21 is fastened directly to the sub-frame mounting base 16 by the fastening member b1.
Further, the rear end portion of the frame portion 21 is fixed to the floor frame 6 and the torque box 8 via a connecting member 15 arranged so as to shift to the vehicle width outer side as the rear side.
The tower portion 12 includes a column portion 13 that extends in the vertical direction, and a tower top portion 14 that corresponds to a mounting portion of the upper arm 24 provided on the top of the column portion 13.

  As shown in FIGS. 3 to 5, a division line PL for the frame portion 21 and the connecting portion 22 is provided at a position corresponding to the front support portion 21 a of the lower arm 23. The dividing line PL is formed by embedding a substantially U-shaped column portion 13 that is outwardly cross-sectionally weak in the front-rear direction in the frame portion 21. Thus, the sub-frame 20 is reliably crushed from the front support portion 21a during a frontal collision of the vehicle, and the absorption of impact energy is increased.

As shown in FIG. 4, the lower arm 23 includes lower arm pivots 23a and 23b on the inner side in the vehicle width direction, the front lower arm pivot 23a is pivotally supported by the front support portion 21a, and the rear lower arm pivot 23b is supported on the rear side. It is pivotally supported by the part 21b.
And in both the support parts 21a and 21b, by setting the axial direction of the lower arm pivots 23a and 23b to the front-rear direction, the two support parts 21a and 21b according to the push-up force acting on the front end part of the lower arm 23 when the vehicle travels. The lower arm 23 is oscillated and displaced with the support shaft as a fulcrum, thereby ensuring the operability of the vehicle.

  The lower arm pivot 23b is attached to the frame portion 21 by a rear support portion 21b, and is pivotally supported by the rear support portion 21b via a cylindrical rubber bush 29. The lower arm pivot 23a is attached to the frame portion 21 via a front support portion 21a formed on the pillar portion 13, and is pivoted to the front support portion 21a via a cylindrical rubber bush 29 in the same manner as the rear support portion 21b. It is supported.

The upper arm 24 (A arm) of the front wheel suspension includes upper arm pivots 24a and 24b on the inner side in the vehicle width direction.
Each front wall portion of the tower top portion 14 constitutes a front support portion 14a that pivotally supports the front upper arm pivot 24a, and each rear wall portion of the tower top portion 14 pivots the rear upper arm pivot 24b. The support part 14b is comprised. In both the support portions 14a and 14b, the axial directions of the upper arm pivots 24a and 24b are set in the vehicle front-rear direction similarly to the lower arm pivots 23a and 23b, and the upper arm pivots 24a and 24b are cylindrical rubber bushes (not shown) Are supported by the support portions 14a and 14b via the abbreviation).

  A stabilizer 25 is provided to suppress the bump angle of only one wheel and the roll angle during rebound by resistance of torsional rigidity. The stabilizer 25 extends in the vehicle width direction and is bent rearward from both ends of the central portion. The left and right ends of the stabilizer 25 are formed on the upper portion of the lower arm 23 near the vehicle outer end via a control link (not shown). Installed. The stabilizer 25 is supported by the tower portion 12 at positions where both ends of the central portion correspond to the front side frame 3 in the vertical direction.

Next, the extension member 9 will be described.
As shown in FIGS. 2 and 4, a pair of left and right extension members 9 extending forward from the middle position in the height direction of the tower portion 12 in the subframe 20 are provided. The extension member 9 is a closed cross-section member having a closed cross section extending substantially in the front-rear direction of the vehicle by joining and fixing an upper member having a concave downward section and a lower member having a concave cross section.

  The extension member 9 has a rear end portion coupled to the column portion 13 by welding means, and extends forward at a position below the front side frame 3. The extension member 9 once detours inward in the vehicle width direction so that its center line avoids the stabilizer support pedestal 17 from the rear end portion, and then forwards while being bent and displaced from the detour portion outward in the vehicle width direction again. It is comprised so that it may protrude. The extension member 9 is coupled at the rear end thereof so that the longitudinal axis is located on the inner side in the vehicle width direction from the center line of the tower portion 12 in the standing direction of the column portion 13.

Next, the under cover member 30 will be described.
The under cover member 30 is made of an aluminum plate material having a predetermined plate thickness (for example, 0.8 mm) corresponding to a preset rigidity, and the left and right sides 1 correspond to below the front end portions of the engine 1 and the transmission 2. It is suspended between the pair of frame portions 21.
As shown in FIG. 1, FIG. 3, FIG. 5, and FIG. 6, the under cover member 30 has a downward projecting concave portion 30a formed in the center portion, and a flange projecting outward from the front side and the left and right sides of the concave portion 30a. The part 30b and an upward projecting convex part 30c extending in the vehicle width direction on the rear side of the concave part 30a are integrally provided.

  A panel member 31 extending in the vehicle width direction is welded to the lower side of the convex portion 30c to form a closed cross section that connects the rear ends of the pair of left and right frame portions 21 in cooperation with the convex portion 30c. . Thereby, the sub-frame 20 and the under cover member 30 cooperate to form a loop-shaped closed cross-sectional structure. A pair of left and right protrusions 31a are formed at the rear end of the panel member 31, and the cover member 18 is connected and supported.

  As shown in FIG. 5, the flange portion 30b has three bolt holes h1 for fastening to the lower portion of the connecting portion 22, and a pair of left and right bolts for fastening to the lower portions of the pair of left and right frame portions 21. A total of 13 bolt holes, that is, a pair of left and right bolt holes h3 for fastening to the pair of left and right connecting members 15 are formed. Out of the three bolt holes h1 on the front side, the bolt holes h1 on the left and right end sides are respectively formed in positions near the connecting portion between the frame portion 21 and the column portion 13. The left and right pairs of bolt holes h3 on the rear side are respectively formed in the vicinity of the connecting portion between the frame portion 21 and the connecting member 15.

As shown in FIGS. 3 and 7, the pair of left and right connecting members 15 are arranged in a substantially C shape in plan view so as to follow the diagonal line DL with respect to the vehicle body. These connecting members 15 are integrally formed of a metal plate material, and each include a vehicle body side fixing portion 15a, a frame portion side fixing portion 15b, and an extension portion 15c. Since the pair of left and right connecting members 15 have a left-right symmetrical structure, the one side connecting member 15 will be mainly described below.
The vehicle body side fixing portion 15a is fastened to the torque box 8 by the fastening member b2 at the vehicle width direction outer portion, and fastened to the floor frame 6 by the fastening member b2 at the vehicle width direction inner portion.
The frame portion side fixing portion 15 b is fastened by a fastening member b <b> 3 at a position in the vehicle width direction inner side of the rear side support portion 21 b in the bottom wall portion of the frame portion 21. As a result, the load input to the rear support portion 21b is distributed to the vehicle body side member via the connecting member 15 immediately after the input.
The extension portion 15c is configured to project inward in the vehicle width direction from the frame portion side fixing portion 15b. The extension portion 15c is formed with a pair of nut portions n on the back surface portion.

When the under cover member 30 is mounted on the vehicle body, first, the connecting member 15 is fixed to the frame portion 21 and the vehicle body side member along the diagonal line DL by the fastening members b2 and b3.
Next, as shown in FIG. 5, the under cover member 30 is fastened to the subframe 20 by the fastening member b4 inserted through the bolt holes h1 and h2, and the connecting member 15 is connected by the fastening member b5 inserted through the bolt hole h3. Fastened to the nut portion n (extension portion 15c).

  Thereby, the vehicle body side fixing portion 15a and the extension portion 15c on one side and the front side support portion 21a on the other side can be arranged on the substantially diagonal line DL, and the load input from the front side support portion 21a of the lower arm 23 is applied to the subframe 20. Without being propagated, the torque box 8 and the floor frame 6 are dispersed via the under cover member 30. Further, when the under cover member 30 is removed from the vehicle body for exchanging oil of the engine 1, etc., even if the plurality of fastening members b4 and b5 are removed, the service is performed in a state in which the connection between the sub frame 20 and the vehicle body side member is maintained. be able to.

Next, operations and effects of the vehicle front body structure of the vehicle V will be described.
In the vehicle front body structure of this vehicle, traveling vibration (load) input from the lower arm 23 to the subframe 20 is transmitted to the vehicle body side members (torque box 8 and floor frame 6) via the under cover member 30 and the connecting member 15. Due to the dispersion, the vibration of the predetermined frequency generated in the subframe 20 can be suppressed regardless of the thickness of the subframe 20, and the road noise transmitted into the passenger compartment C can be reduced. Therefore, both the weight reduction of the vehicle body and the reduction of road noise can be achieved.

Each frame portion 21 includes a front side support portion 21 a and a rear side support portion 22 a that support the lower arm 23, and is fixed to the vehicle body side fixing portion 15 a fixed to the vehicle body side member to each connecting member 15 and one frame portion 21. Frame portion side fixing portion 15b, and the front side support portion 21a of the left and right frame portion 21 is set on an extension line connecting the vehicle body side fixing portion 15a and the extension portion 15c of either one of the left and right connecting members 15. doing.
As a result, the front support portion 21a having a large input load and the vehicle body side fixing portion 15a are connected to each other in a diagonal straight line, so that the distance between the front support portion 21a and the vehicle body side member 15a can be minimized, and the subframe The vibration of the predetermined frequency which arises in 20 can be suppressed further.

The vehicle body side fixing portion 15a is fixed to a floor frame 6 extending in the front-rear direction and a torque box 8 connecting the floor frame 6 and the side sill 7 to each other.
As a result, the input load is efficiently distributed to the floor frame 6 and the torque box 8, so that vibration of a predetermined frequency that occurs in the subframe 20 can be further suppressed.

The sub-frame 20 includes a connecting portion 22 that connects the front ends of the pair of left and right frame portions 21, and forms a closed cross-section portion that connects the rear ends of the pair of left and right frame portions 21 in cooperation with the under cover member 30. A panel member 31 is provided.
According to this, since the movement of the rear ends of the pair of left and right frame portions 21 is restricted, it is possible to further suppress the vibration of the predetermined frequency that occurs in the subframe 20.

Next, a modified example in which the embodiment is partially changed will be described.
1) In the above-described embodiment, the example applied to the wishbone type suspension has been described. However, at least one pair of left and right suspension arms are supported by a pair of left and right frame parts via a support part so as to be swingable. It can be applied to various suspensions such as a multi-link suspension.

2) In the above embodiment, the example in which the under cover member is made of an aluminum plate material having a predetermined rigidity has been described. However, at least traveling vibration input from the lower arm to the subframe is transmitted to the connecting member via the under cover member. As long as it can be transmitted, another metal material such as steel may be used as the undercover member, and a synthetic resin material (for example, a glass fiber-containing synthetic resin material) having a predetermined rigidity may be used.

3] In the above-described embodiment, the example in which the input load is distributed from the lower arm to the floor frame and the torque box has been described. However, the connection member may be provided so as to be distributed only to the floor frame or only to the torque box.

4) In addition, those skilled in the art can implement the present invention with various modifications added without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

V Vehicle 6 Floor frame 7 Side sill 8 Torque box 15 Connection member 15a Car body fixing part 15b Frame part side fixing part 15c Extension part 20 Subframe 21 Frame part 21a Front side support part 21b Rear side support part 22 Connection part 30 Under cover member 31 Panel Element

Claims (4)

A vehicle including a pair of left and right suspension arms that rotatably support the front wheels, and a sub-frame having a pair of left and right frame portions that respectively swingably support the pair of left and right suspension arms via a support portion. In the front body structure of
An under cover member that is fixed to the pair of left and right frame parts and covers a space between the pair of left and right frame parts from below;
A pair of left and right connecting members that connect the pair of left and right frame portions to a vehicle body side member;
A vehicle body structure for a front portion of a vehicle, wherein the pair of left and right connecting members are respectively formed with extensions extending inward in the vehicle width direction and connected to the under cover member. Each frame portion includes a front support portion and a rear support portion that support the suspension arm,
Each connecting member is provided with a vehicle body side fixing portion fixed to the vehicle body side member and a frame portion side fixing portion fixed to the one frame portion,
2. The vehicle according to claim 1, wherein a front support portion of the left or right frame portion is set on an extension line connecting a vehicle body side fixing portion and an extension portion of either of the left and right connection members. Front body structure.   The vehicle front body structure according to claim 1 or 2, wherein the vehicle body side fixing portion is fixed to a floor frame extending in the front-rear direction and a torque box connecting the floor frame and the side sill. The sub-frame includes a connecting portion connecting the front ends of the pair of left and right frames;
The panel member which forms the closed cross-section part which cooperates with the said undercover member and connects the rear end of the pair of left and right frame parts is provided. The front body structure of the vehicle.