JP2021017149A - Front sub frame structure - Google Patents

Abstract

To provide a front sub frame structure capable of being folded and deformed downward surely, with a fragile part as an origin, when a front collision load is input.SOLUTION: A front sub frame structure comprises: a pair of right and left side members 16, 16 extending in a vehicle longitudinal direction; a cross member 18 extending in a vehicle width direction; load reception parts each of which is provided on a vehicle front end of each side member 16 for receiving a load from a vehicle front side; fitting points provided on a vehicle body side member; brackets 27 each of which is provided between the fitting point along a vehicle longitudinal direction of the side member and a fragile part, and to which a stabilizer 24 is fitted; and fragile parts 30 for promoting folding/deformation downward of each side member 16 when a front collision load is input. An inside flange part 44 in a vehicle width direction inside of each bracket 27 is provided in parallel to a side face of an inside side wall 17c of the side member 16 in the vehicle width direction inside.SELECTED DRAWING: Figure 2

Description

The present invention relates to a front subframe structure arranged in front of the vehicle.

For example, Patent Document 1 discloses a subframe structure in which a load receiving portion is provided at a vehicle front end of a side member of the subframe.

In this subframe, a mounting point for mounting the subframe to the vehicle body is provided at a portion outside the vehicle width direction of the load receiving portion, and the side member is viewed from the side to promote bending of the side member. A curved portion is provided.

Japanese Patent No. 5982843

By the way, in the subframe structure disclosed in Patent Document 1, the side member is inclined inward in the vehicle width direction from the attachment point of the side member to the curved portion, and when the front impact load is input to the load receiving portion, the side member is on the outside. There is a risk of bending and deforming toward.

Therefore, in the subframe structure disclosed in Patent Document 1, it is difficult to move or drop the subframe downward.

The present invention has been made in view of the above points, and provides a front subframe structure capable of reliably bending and deforming downward from a fragile portion as a starting point when a frontal impact load is input. The purpose is to do.

In order to achieve the above object, the present invention comprises a pair of left and right side members extending in the front-rear direction of the vehicle, a cross member extending in the vehicle width direction between the pair of left and right side members, and a vehicle front end of each side member. A load receiving portion provided in the vehicle to receive a load from the front of the vehicle, an attachment point attached to a member on the vehicle body side, and an attachment point provided behind the attachment point and below each side member when a load is input from the front of the vehicle. It is a front subframe structure having a fragile portion that promotes bending and deformation toward the vehicle, and is provided between the attachment point and the fragile portion along the vehicle front-rear direction of each side member, and a stabilizer is attached. The bracket is provided, and at least one of the inner edge portion on the inner side in the vehicle width direction of the bracket or the outer edge portion on the outer side in the vehicle width direction of the bracket is provided parallel to the inner side wall portion in the vehicle width direction of each side member. It is characterized by that.

According to the present invention, it is possible to obtain a front subframe structure capable of reliably bending and deforming downward from a fragile portion as a starting point when a frontal impact load is input.

It is a perspective view which looked at the front part of the vehicle which incorporated the front subframe which concerns on embodiment of this invention from diagonally above. It is a top view of the front subframe shown in FIG. It is a top view which shows the state which the stabilizer is attached to the stabilizer attachment part, and the steering gearbox is attached to the gearbox attachment part. It is a bottom view which looked at the state shown in FIG. 3 from the bottom side. It is a vertical cross-sectional view along the VV line of FIG. It is a partially omitted enlarged perspective view of the right side member and the bracket as viewed from the diagonal direction in front of the vehicle. It is an arrow view seen from the arrow Z direction of FIG. FIG. 7 is an enlarged vertical sectional view taken along the line VIII-VIII of FIG. It is a top view of the right side member and a bracket shown in FIG. It is a top view which shows the state which removed the bracket from the state shown in FIG.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
In each figure, "front and rear" indicates the vehicle front and rear direction, "left and right" indicates the vehicle width direction (left and right direction), and "up and down" indicates the vehicle vertical direction (vertical vertical direction).

A front subframe 10 according to an embodiment of the present invention is arranged in front of the vehicle. The front subframe 10 is attached to the lower side of a pair of left and right front side frames 12 and 12 (see FIG. 4) extending along the vehicle front-rear direction. Further, the front subframe 10 supports a suspension device for front wheels (not shown) and a power unit (a drive source such as a motor or an engine) via a mount mechanism (not shown).

As shown in FIGS. 1 and 2, the front subframe 10 includes a pair of left and right side members 16 and 16, a cross member 18, and a pair of braces 20 and 20.

The front subframe 10 has a substantially H-shape in a plan view due to the pair of left and right side members 16, 16 and the cross member 18 (see FIG. 2). Further, the vehicle front end portion 16a of each side member 16 is provided in a front-opening state located outside the vehicle rear end portion 16b of each side member 16 in the vehicle width direction.

The pair of left and right side members 16, 16 have a closed cross section having a rectangular cross section in the vertical axis (see FIG. 8), and extend substantially along the vehicle front-rear direction. The vehicle front end portion 16a of each side member 16 is connected to the front side frame 12 via a vehicle body mounting portion 15 connected to the connecting frame 22 extending upward (see FIG. 5). The vehicle rear end 16b of each side member 16 is connected to the vehicle front end 14a of the front panel 14 (see FIG. 4). The vehicle front end portion 16a of each side member 16 functions as a "load receiving portion" within the scope of the claims.

As shown in FIG. 3, a pair of left and right stabilizer mounting portions 26 to which the stabilizer 24 is mounted are provided on the upper surface of each side member 16. Each stabilizer mounting portion 26 is provided between the connecting frame 22 (see FIG. 4) and the cross member 18 (see FIG. 5) on the upper surface of each side member 16 on the vehicle front side. Each stabilizer mounting portion 26 has a pair of left and right stabilizer holders 28 that project upward from the upper surface of each side member 16 and hold an intermediate portion of the stabilizer 24.

Next, the front side of each side member 16 will be described in detail below.

As shown in FIG. 8, each side member 16 has an upper wall 17a and a lower wall 17b facing each other in the vertical direction, and both side flanges of the upper wall 17a and both side flanges of the lower wall 17b are joined to each other in the vehicle width direction. Has an inner side wall 17c and an outer side wall 17d facing each other.

The upper surface of the upper wall 17a of each side member 16 has a first step portion 19a and a second step portion 19b extending along the axial direction of the side member 16 (see FIG. 10). A recess 21 is formed between the first stepped portion 19a and the second stepped portion 19b, which is recessed downward from the upper surface of the upper wall 17a (see FIG. 8). The recess 21 forms a hollow portion 48 having a closed cross section between the lower surface of the bracket 27, which will be described later, and the recess 21 on the upper surface of the side member 16 (see FIG. 8).

As shown in FIG. 8, the first step portion 19a is formed by a cross-sectional inclined surface that descends from the upper surface of the upper wall 17a inside in the vehicle width direction toward the recess 21 on the outside in the vehicle width direction. The second step portion 19b is formed by a cross-sectional inclined surface that descends from the upper surface of the upper wall 17a on the outer side in the vehicle width direction toward the recess 21 on the inner side in the vehicle width direction.

Further, on the upper surface of each side member 16, a vehicle body mounting portion 15 connected to the front side frame (vehicle body side member) 12 via the connecting frame 22 is provided at a portion in front of the vehicle from the stabilizer mounting portion 26. Has been done. The vehicle body mounting portion 15 has a circular shape when viewed in a plan view, and is composed of a convex portion 23 projecting upward. The vehicle body mounting portion 15 is located in front of the vehicle body with respect to the outer flange portion 46 of the bracket 27 described later, and is located on the extension line L of the outer flange portion 46 (see FIG. 9). This point will be described in detail later.

A mounting point 13 is provided at the center of the vehicle body mounting portion 15 in a plan view (see FIGS. 2 and 3). The attachment point 13 attached to the front side frame 12 which is a vehicle body side member is located outside in the vehicle width direction at the front end of each side member 16 of the vehicle. In the present embodiment, a load receiving portion (vehicle front end portion 16a) is provided at the front end of the vehicle of each side member 16, and the attachment point 13 is arranged outside the load receiving portion in the vehicle width complementary direction.

Further, each side member 16 has a pair of left and right connecting portions 25, 25 at which both ends of the cross member 18 along the vehicle width direction are connected at a position rearward of the fragile portion 30, which will be described later.

Since the pair of left and right stabilizer holders 28 are arranged symmetrically, the right stabilizer holder 28 will be described in detail, and the left stabilizer holder 28 will be omitted.

As shown in FIG. 5, the stabilizer holder 28 has a bracket 27, a holding portion 29, and a fastening fixing portion 31.

The bracket 27 is made of a plate body having a vertically long rectangular shape in a plan view, and is fixed (joined) to the upper surface of the upper wall 17a of the side member 16. Further, the bracket 27 is located in front of the vehicle with respect to the fragile portion 30 described later. The axial cross section of the central portion of the bracket 27 is formed in a substantially hat shape (see FIG. 8).

The bracket 27 has a bracket main body 40, a welded portion 42, an inner flange portion 44, and an outer flange portion 46. The bracket body 40 is composed of a flat plate body.

The welded portion 42 is located at the vehicle front end of the bracket 27 in a plan view and extends along the vehicle width direction. Further, the welded portion 42 projects from the front end of the bracket body 40 toward the front of the vehicle. Further, the vehicle front end 42a of the welded portion 42 is located in front of the vehicle with respect to the vehicle rear end 23a of the convex portion 23 constituting the vehicle body mounting portion 15 (see FIG. 7). Both ends of the welded portion 42 in the vehicle width direction are notched and formed, and are not continuous with the vehicle front end of the inner flange portion 44 and the vehicle front end of the outer flange portion 46.

In a plan view, an inner flange portion (inner edge portion) 44 continuous with the bracket main body 40 is provided inside the bracket 27 in the vehicle width direction. The inner flange portion 44 extends along the front-rear direction of the vehicle. The inner flange portion 44 of the bracket 27 is provided parallel to the side surface of the inner side wall 17c provided inside each side member 16 in the vehicle width direction (see FIG. 9). The inner flange portion 44 is joined to the upper surface of the upper wall 17a of the side member 16 via a welding device (not shown) (see FIG. 8). A set of mounting holes 47 are arranged in the bracket body 40 so as to be parallel to the vehicle front-rear direction (see FIG. 9).

An outer flange portion (outer edge portion) 46 continuous with the bracket main body 40 is provided on the outer side of the bracket 27 in the vehicle width direction. The outer flange portion 46 extends along the front-rear direction of the vehicle. As shown in FIG. 9, a convex portion 23 of the vehicle body mounting portion 15 is provided on the extension line L of the outer flange portion 46 facing the front of the vehicle. The outer flange portion 46 is joined to the upper surface of the upper wall 17a of the side member 16 via a welding device (not shown) (see FIG. 8).

As shown in FIG. 1, the vehicle rear end 44a of the inner flange portion 44 of the bracket 27 and the vehicle rear end 46a of the outer flange portion 46 of the bracket 27 are welded to the vehicle front end 30a of the fragile portion 30, respectively. There is.

In the present embodiment, the case where the inner flange portion 44, which is the inner edge portion, is parallel to the side surface of the inner side wall 17c is shown as an example, but the present invention is not limited to this. The outer flange portion 46, which is the outer edge portion, may be provided parallel to the side surface of the inner side wall 17c. At least one of the inner flange portion 44 or the outer flange portion 46 may be parallel to the side surface of the inner side wall 17c.

As shown in FIG. 5, the holding portion 29 is placed on the bracket 27, and the two half elements are put together to surround and hold the outer peripheral surface of the stabilizer 24.

The fastening fixing portion 31 has a set of bolt insertion holes arranged apart from each other in the front-rear direction of the vehicle, and holds the holding portion 29 and the bracket 27 via bolts and nuts (not shown) inserted into the bolt insertion holes. It is fastened and fixed to the side member 16.

As shown in FIG. 3, the stabilizer 24 is made of, for example, a hollow pipe material, and has a linear extending portion 24a, a bending portion 24b, and a rear extending portion 24c. The linear extending portion 24a extends substantially linearly along the vehicle width direction. The bent portion 24b is bent toward the rear of the vehicle from the outer end portion of the linear extending portion 24a in the vehicle width direction. The rear extending portion 24c extends outward from the bent portion 24b toward the rear of the vehicle in the vehicle width direction. The ends of the stabilizer 24 are fixed to a pair of left and right suspension arms 33 (see FIG. 3).

The stabilizer holder 28 holds a portion on the front side of the bent portion 24b at the left and right outer ends of the linear extending portion 24a of the stabilizer 24 (see FIG. 3).

Further, as shown in FIGS. 1 and 2, each side member 16 is provided with a fragile portion 30 that causes a downward bending deformation from an intermediate portion of the side member 16 when a collision load is input. The fragile portion 30 is an intermediate portion of each side member 16 along the vehicle front-rear direction, and is provided between the cross member 18 and the stabilizer mounting portion 26. Further, the fragile portion 30 is located behind the vehicle in the front-rear direction of the vehicle with respect to the bracket 27 joined to the upper surface of the side member 16.

As shown in FIGS. 1, 5, and 7, in the present embodiment, the fragile portion 30 is composed of a step 32 provided on the upper surface of each side member 16. The step 32 extends along a direction (vehicle width direction) orthogonal to the axis of the side member 16 in a plan view.

The cross member 18 extends along the vehicle width direction between the pair of left and right side members 16 and the central portion of the 16. Further, the cross member 18 has a pair of left and right gearbox mounting portions 36 to which the steering gearbox 34 is mounted (see FIGS. 1 and 2). Each gear box mounting portion 36 has a bolt fastening hole arranged on the vehicle front end side of the cross member 18 in a plan view, and the mounting flange of the steering gear box 34 is of the cross member 18 via bolts and nuts. It is fixed to the gearbox mounting portion 36 (see FIG. 3). The stabilizer mounting portion 26 is arranged at a position offset outward in the vehicle width direction with respect to the gear box mounting portion 36.

As shown in FIG. 4, the pair of braces 20 and 20 are arranged behind the cross member 18 and are connected so as to hang the pair of left and right side members 16 and 16 in a crossing shape. The vehicle front end of each brace 20 is fastened and fixed to the vehicle rear portion of the cross member 18 via bolts B. Further, the rear end portion of each brace 20 is connected and fixed to the inside of the side member 16 in the vehicle width direction via a bolt B (see FIG. 4).

The front subframe 10 according to the present embodiment is basically configured as described above, and the effects thereof will be described next.

In the present embodiment, there is a bracket to which the stabilizer is attached located in front of the fragile portion of each side member, and the inner flange portion (inner edge portion) 44 of the bracket 27 is the side surface of the inner side wall 17c of the side member 16. It is provided in parallel with.

Thereby, in the present embodiment, it is possible to secure the desired rigidity and strength against the front impact load input from the front of the vehicle, and the front impact load input from the front of the vehicle is smoothly applied to the rear of the vehicle along each side member 16. Can be communicated to. As a result, in the present embodiment, even when the front impact load is input from the front of the vehicle, it is possible to prevent each side member 16 from opening or bending and deforming outward in the vehicle width direction, and the front sub The frame 10 can be reliably folded downward.

In the present embodiment, the inner flange portion (inner edge portion) 44 of the bracket 27 and the side surface of the inner side wall 17c of the side member 16 are provided in parallel to provide resistance to a collision load input from the front of the vehicle. The side member 16 and the bracket 27 can work together to improve the load transmission efficiency. As a result, in the present embodiment, it is possible to efficiently transmit the front impact load to the fragile portion 30 by avoiding the occurrence of bending deformation at the vehicle front portion rather than the fragile portion 30 due to the front impact load. .. As a result, in the present embodiment, it is possible to obtain a front subframe structure that can be reliably bent and deformed starting from the fragile portion 30 when a front impact load is input.

Further, in the present embodiment, the vehicle rear end 44a of the inner flange portion 44 of the bracket 27 and the vehicle rear end 46a of the outer flange portion 46 of the bracket 27 are welded to the vehicle front end 30a of the fragile portion 30, respectively. ..

Thereby, in the present embodiment, the load input from the front of the vehicle can be efficiently transmitted to the fragile portion 30. As a result, in the present embodiment, even when the front impact load is input from the front of the vehicle, it is possible to further suppress the side members 16 from opening or bending and deforming outward in the vehicle width direction. The front subframe 10 can be reliably folded downward.

Further, in the present embodiment, each side member 16 has a pair of left and right connecting portions 25, 25 which are connected to both ends of the cross member 18 along the vehicle width direction at a position rearward of the vehicle from the fragile portion 30. ing. In the present embodiment, by providing each connecting portion 25, the rigidity and strength of the portion rear of the vehicle can be improved as compared with the fragile portion 30. As a result, in the present embodiment, a difference in rigidity / strength is generated between the fragile portion 30 and the connecting portion 25 of each side member 16, and the fragile portion 30 can be reliably deformed.

Further, in the present embodiment, the connecting point 13 is arranged outside the front end portion 16a of the vehicle, which is the load receiving portion, in the vehicle width direction, and is arranged on the extension line L of the outer flange portion 46 of the bracket 27 facing the front of the vehicle. A vehicle body mounting portion 15 that is attached to the front side frame (vehicle body side member) 12 via the connecting frame 22 is provided.

As a result, in the present embodiment, the front impact load concentrated on the vehicle body mounting portion 15 can be transmitted to the rear of the vehicle through the outer flange portion 46 which is the outer edge portion of the bracket 27, and is located in the front portion of the vehicle rather than the stabilizer mounting portion 26. It is possible to avoid the occurrence of buckling.

Further, in the present embodiment, the bracket 27 has a welded portion 42 located at the front end portion of the vehicle and extending along the vehicle width direction in a plan view. The vehicle front end 42a of the welded portion 42 is arranged in front of the vehicle with respect to the vehicle rear end 23a of the convex portion 23 of the vehicle body mounting portion 15 (see FIG. 7).

Thereby, in the present embodiment, it is possible to suppress the occurrence of bending deformation between the vehicle body mounting portion 15 and the inner flange portion 44 and the outer flange portion 46 of the bracket 27. As a result, in the present embodiment, the fragile portion 30 can be bent and deformed even more effectively.

Furthermore, in the present embodiment, each side member 16 has a first step portion 19a and a second step portion 19b extending along the axial direction of the side member 16. The first step portion 19a and the second step portion 19b are located in front of the fragile portion 30 and below the inner flange portion 44 and the outer flange portion 46, and are formed in parallel with each other.

As a result, in the present embodiment, the side members 16 are provided with the first and second stepped portions 19a and 19b, respectively, to more effectively secure the rigidity and strength of the vehicle front portion than the break point (fragile portion 30). It is possible to prevent buckling in front of the vehicle from the break point.

Furthermore, in the present embodiment, a recess 21 that is recessed downward is formed between the first step portion 19a and the second step portion 19b. Thereby, in the present embodiment, the support rigidity / support strength of the side member 16 with respect to the load input from the stabilizer 24 can be increased.

Further, in the present embodiment, a hollow portion 48 having a closed cross section is formed between the lower surface of the bracket 27, which is the stabilizer mounting portion 26, and the upper surface of the side member 16. In the present embodiment, for example, when the front subframe 10 is deformed by the front impact load, the hollow portion 48 can suitably absorb the load when the stabilizer 24 comes into contact with the rear portion of the front subframe 19. .. In other words, in the present embodiment, since the bracket 27 can be deformed only in the hollow portion 48, the load can be suitably absorbed by the deformation of the bracket 27.

10 Front subframe 12 Front side frame (body side member)
13 Mounting point 15 Body mounting part 16 Side member 16a (side member) Front end of vehicle (load receiving part)
17c Inner side wall (of side member) 18 Cross member 19a 1st step 19b 2nd step 21 Concave 23 Convex 24 Stabilizer 25 Connecting part 26 Stabilizer mounting part 27 Bracket 30 Fragile part 30a (Fragile part) Vehicle front end 42 Welding Part 44 Inner flange part (inner edge part)
44a (inner flange) Vehicle rear end 46 Outer flange (outer edge)
46a (outer flange) vehicle rear end

Claims (7)

A pair of left and right side members extending in the front-rear direction of the vehicle, a cross member extending in the vehicle width direction between the pair of left and right side members, and a load receiver provided at the front end of each side member to receive a load from the front of the vehicle. It has a portion, a mounting point attached to a member on the vehicle body side, and a fragile portion provided behind the mounting point and promoting downward bending deformation of each side member when a load is input from the front of the vehicle. It has a front subframe structure
A bracket provided between the attachment point and the fragile portion along the vehicle front-rear direction of each side member and to which a stabilizer is attached is provided.
At least one of the inner edge portion on the inner side in the vehicle width direction of the bracket or the outer edge portion on the outer side in the vehicle width direction of the bracket is provided parallel to the inner side wall in the vehicle width direction of each of the side members. Front subframe structure. In the front subframe structure according to claim 1,
A front subframe structure characterized in that the vehicle rear end of the bracket is welded to the vehicle front end of the fragile portion. In the front subframe structure according to claim 1 or 2.
The front subframe structure is characterized in that each side member has a connecting portion in which both ends of the cross member along the vehicle width direction are connected to each other behind the fragile portion. In the front subframe structure according to any one of claims 1 to 3.
The attachment point is arranged outside the load receiving portion in the vehicle width direction.
A front subframe structure characterized in that a vehicle body mounting portion to be attached to the vehicle body side member is provided on an extension line of the outer edge portion of the bracket. In the front subframe structure according to claim 4,
The vehicle body mounting portion has a convex portion that protrudes upward.
The bracket has a welded portion located at the front end of the vehicle in a plan view and extending along the vehicle width direction.
The front subframe structure is characterized in that the welded portion is arranged in front of the vehicle with respect to the rear end of the convex portion of the vehicle. In the front subframe structure according to any one of claims 1 to 5.
Each of the side members has a first step portion and a second step portion extending along the axial direction of the side member.
The front is characterized in that the first step portion and the second step portion are located in front of the fragile portion and are formed parallel to each other below the inner edge portion and the outer edge portion. Subframe structure. In the front subframe structure according to claim 6,
A front subframe structure characterized in that a recess recessed downward is formed between the first step portion and the second step portion.

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