WO2023002231A1

WO2023002231A1 - A sub-frame structure for a vehicle

Info

Publication number: WO2023002231A1
Application number: PCT/IB2021/056543
Authority: WO
Inventors: Pornchanok ARUNSIRI; Nattakit DILOKTIANSAK
Original assignee: Asian Honda Motor Co., Ltd.
Priority date: 2021-07-20
Filing date: 2021-07-20
Publication date: 2023-01-26

Abstract

The present invention discloses a sub-frame structure 1 for a vehicle including: a left side arm 10 arranged to extend forward from a sub-frame body 2; and a right side arm 20 arranged to extend forward from the sub-frame body 2. Each of the left side arm 10 and the right side arm 20 includes an inner frame 30 and an outer frame 40 that is formed so as to cover the inner frame 30 from above. The inner frame 30 includes a second inner frame side wall 34 with a recess portion R2 which is formed to recess downwardly at an upper end 34a of the second inner frame side wall 34. A lower end 44a of a second outer frame side wall 44 of the outer frame 40 is arranged to contact with the recess portion R2 and to overlap with the recess portion R2 when viewed from above.

Description

A SUB-FRAME STRUCTURE FOR A VEHICLE

FIELD OF INVENTION

The present invention relates to a sub-frame structure for a vehicle.

BACKGROUND OF THE INVENTION

It is known that a sub-frame structure for a vehicle includes a left side member and a right side member, each of which includes an upper member and a lower member are attached each other by welding over the entire length, as is disclosed in the description of US Publication of Unexamined Patent Application No. 2020/307704A1 hereinafter called PTL1.

In PTL1, for the purpose of deforming the sub-frame in a desired deformation mode in frontal collision of the vehicle, the lower member includes a concave portion as well as the upper member includes a concave portion and fragile portions. By providing the concave portions and the fragile portions in a predetermined positions, the sub-frame structure controls the deformation direction when the impact is applied to the front of the sub-frame structure.

However, the upper member and the lower member are attached each other by welding over the entire length to improve the strength and the rigidity. It is necessary to form the upper member and the lower member having a complicated shape in which the concave portions and the fragile potions are provided in places other than welded portions in order to achieve both the fragile performance and the desired deformation mode. Therefore, there is a possibility that it is difficult for the sub-frame structure to obtain the desired fragile performance due to the complicated shape of the upper member and the lower member.

Therefore, the development of the sub-frame structure which, with a simple configuration, can form the fragile portion at the desired position and ensure the strength and the rigidity of the sub-frame, as well as can control the deformation direction of the sub-frame when the impact is applied to the front of the sub-frame structure, is required.

CITATION LIST Patent Literature

PTL 1: The description of US Publication of Unexamined Patent Application No 2020/307704A1 SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a sub- frame structure for a vehicle, which, with a simple configuration, can easily form the fragile portion at the desired position and ensure the strength and the rigidity of the sub-frame, as well as can control the deformation direction of the sub-frame when the impact is applied to the front of the sub-frame structure.

In order to achieve the above objective, an embodiment of the present invention provides a sub-frame structure for a vehicle, which is attached to a vehicle body comprising: a sub-frame body; a left side arm which is arranged to extend forward from the sub-frame body and arranged at a left side in a vehicle width direction; and a right side arm which is arranged to extend forward from the sub-frame body and arranged at a right side in the vehicle width direction, wherein each of the left side arm and the right side arm includes an inner frame and an outer frame that is formed so as to cover the inner frame from above, the inner frame includes a first inner frame side wall, a second inner frame side wall and a base plate, and the outer frame includes a first outer frame side wall, a second outer frame side wall and a top plate, wherein the inner frame includes the second inner frame side wall with a recess portion which is formed to recess downwardly at an upper end of the second inner frame side wall, and wherein a lower end of a second outer frame side wall of the outer frame is arranged to contact with the recess portion and to overlap with the recess portion when viewed from above.

According to the embodiment of the present invention, firstly, the recess portion is formed to recess downwardly at the upper end of the second inner frame side wall of the inner frame as well as the lower end of the second outer frame side wall of the outer frame is arranged to contact with the recess portion and to overlap with the recess portion when viewed from above.

As such, the recess portion can function as an element which supports the second outer frame side wall of the outer frame from below. As a result, since it is not necessary to fix the recess portion of the inner frame and the outer frame by welding, etc. , a fragile portion can be easily formed in the sub-frame structure without adding any other elements in the area where the recess portion is arranged.

Secondly, even if the outer frame is not fixed to the recess portion of the inner frame, it is possible to easily ensure the strength and the rigidity of the sub-frame structure by fixing the outer frame and the inner frame other than the recess portion by welding, etc.

Thirdly, in case where the impact is applied to the front of the sub- frame structure, since there is differences about the strength and the rigidity between the fragile portion and the other portion of the inner frame and the outer frame, it is possible to control the deformation direction of the sub-frame.

Therefore, the sub- frame structure for the vehicle of the embodiment of the present invention, with a simple configuration, can easily form the fragile portion at the desired position and ensure the strength and the rigidity of the sub- frame, as well as can control the deformation direction of the sub-frame when the impact is applied to the front of the sub-frame structure.

In the sub-frame structure for the vehicle of the embodiment of the present invention, each of the left side arm and the right side arm includes a curved portion which are formed to curve toward the outside of the vehicle, wherein the curved portion includes a first deformation area formed by a lower area which is part of the first inner frame side wall formed so as to protrude outward and curve, and an upper area which is part of the first outer frame side wall located above the lower area of the first deformation area, wherein the curved portion further includes a second deformation area formed by a lower area which is a part of the second inner frame side wall formed so as to protrude outward and curve, and an upper area which is part of the second outer frame side wall located above the lower area of the second deformation area, and wherein the second recess portion is arranged so as to face the first deformation area.

According to the sub- frame structure of the embodiment of the present invention, the recess portion is arranged so as to face the first deformation area.

As such, in each of the left side arm and the right side arm, even if there is only the one deformation area that include the recess portion which contacts with the lower end of the second outer frame side wall, in case that the impact is applied to the front of the sub-frame structure, the left side arm and the right side arm are easily bent at each deformation area.

Therefore, it is possible to surely control the deformation direction of the sub- frame structure when the impact is applied to the front of the sub-frame structure.

In the sub- frame structure for the vehicle of the embodiment of the present invention, the first deformation area includes another recess portion which is formed to recess downwardly at the first inner frame side wall of the inner frame.

According to the sub- frame structure of the embodiment of the present invention, since the first deformation area includes another recess portion as a fragile portion, in case where the impact is applied to the front of the sub- frame structure, the first inner frame side wall and the first outer frame side are surely bent at the position of the another recess portion in the first deformation area. As such, it is possible to more surely control the deformation direction of the sub-frame structure when the impact is applied to the front of the sub-frame structure. Furthermore, since it is possible to more surely control the deformation direction of the sub- frame, the degree of the curvature of the curved portion can be reduced. Therefore, not only the weight of the sub- frame structure can be reduced by the recess portion and the another recess portion, but also the manufacturing processes and the manufacturing cost can be reduced by reducing the degree of the curvature of the curved portion as well as the first deformation area and the second deformation area.

BRIEF DESCRIPTION OF DRAWINGS

The principle of the present invention and its advantages will become apparent in the following description taking in consideration with the accompanying drawings in which:

FIG.1 A is a plane view of a sub-frame structure 1 for a vehicle according to an embodiment of the present invention;

FIG. IB is an enlarged view of a curved portion 3 in FIG.1;

FIG.2A is an explanation view about deformation areas by seeing through an outer frame when viewed from diagonally above;

FIG.2B is an explanation view about deformation areas by seeing through the outer frame when viewed from another diagonally above, different from FIG.2A;

FIG.3 is a cross sectional view taken along line III -III of FIG.1 A;

FIG.4A is an explanation view about an inner frame 30 when viewed from diagonally above; FIG.4B is an explanation view about the inner frame 30 when viewed from another diagonally above, different from FIG.4A;

FIG.5 A is an explanation view about an outer frame 40 when viewed from diagonally above; FIG.5B is an explanation view about the outer frame 40 when viewed from another diagonally above, different from FIG.5A.

DETAILED DESCTIPTION OF EMBODIMENTS OF THE INVENTION Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 1 to FIG.5B. Unless otherwise specified, front, rear, left and right directions in the following description indicate the front, rear, left, right directions of the vehicle, respectively.

As shown in FIG.1 and FIG.2, a sub-frame structure 1 for a vehicle is provided in the front portion of the vehicle and attached to a vehicle body (not shown), and includes a sub-frame body 2 arranged on the rear side in a vehicle front-rear direction, a left side arm 10 which is connected to the sub-frame body 2, a right side arm 20 which is connected to the sub-frame body 2. The sub- frame structure 1 supports suspension parts (not shown), etc.

The sub- frame body 2 includes a rear edge 2a that is curved so that the central part is recessed toward the front, and left and right side edges 2b, 2c that extend outward in the vehicle width direction as the left and right side edges 2b, 2c extend forward, and a front edge 2d that extends along the vehicle width direction, when viewed from above. A pair of extending portions 2e,2e extending rearward are provided on both sides of the rear end of the sub-frame body 2.

The left side arm 10 is arranged to extend forward from the sub-frame body 2 and arranged at a left side in a vehicle width direction. The right side arm 20 is arranged to extend forward from the sub- frame body 2 and arranged at a right side in the vehicle width direction. Each of the left side arm 10 and the right side arm 20 includes a curved portion 3 which is formed to curve toward the outside of the vehicle. Since the pair of the left side arm 10 and the right side arm 20 are formed symmetrically with each other, the left side arm 10 arranged on the left side will be described in the following description unless otherwise specified.

The left side arm 10 includes an inner frame 30 and an outer frame 40 that is formed so as to cover the inner frame 30 from above. The inner frame 30 has a U-shaped cross section that opens upward, as well as includes a pair of a first inner frame side wall 32 facing the right side arm 20 and a second inner frame side wall 34 facing outward, which face each other in the left- right direction, and a base plate 36 that connects lower end edges of the pair of the first inner frame side wall 32 and the second inner frame side wall 34 (See FIG.3).

Moreover, the outer frame 40 has a U-shaped cross section that opens downward, as well as includes a pair of a first outer frame side wall 42 facing the right side arm 20 and a second outer frame side wall 44 facing outward, which face each other in the left-right direction, and a top plate 46 that connects upper end edges of the pair of the first outer frame side wall 42 and the second outer frame side wall 44 (See FIG.3).

The inner frame 30 includes the first inner frame side wall 32 with a first recess portion R1 which is formed to recess downwardly at an upper end 32a of the first inner frame side wall 32. The first recess portion R1 is formed so as to be cut out in a substantially rectangular shape at an upper end portion of the first inner frame side wall 32 when viewed from the side of the inner frame 30.

Moreover, to make it easier to bend the first inner frame side wall 32 and the first outer frame side wall 42 at the position of the first recess portion R1 when the impact is applied to the front of the sub- frame structure 1, the first recess portion R1 is included in the curved portion 3 of the left side arm 10.

As shown in FIG.2A and FIG. 5B, the curved portion 3 includes a first deformation area D 1 which is formed by a lower area D la which is part of the first inner frame side wall 32 formed so as to protrude outward and curve, and an upper area Dlb which is part of the first outer frame side wall 42 located above the lower area D la of the first deformation area D 1. Namely, the first deformation area D1 is an inside deformation area of the inner frame 30 and the outer frame 40.

Furthermore, in this embodiment, for the purpose of surely controlling the deformation direction of the sub-frame, the first deformation area D1 includes the first recess portion Rl.

As shown in FIG.3, a lower end 42a of the first outer frame side wall 42 of the outer frame 40 is arranged to contact with the first recess portion Rl and to overlap with the first recess portion Rl when viewed from above. Namely, except for an area where the lower end 42a of the first outer frame side wall 42 of the outer frame 40 contacts with the first recess portion Rl, the other part of the lower end 42a of the first outer frame side wall 42 of the outer frame 40 does not contact with the upper end 32a of the first inner frame side wall 32 as well as the outer frame 40 is arranged to cover the inner frame 30 when viewed from above.

For the purpose of forming a fragile portion, the first recess portion Rl and the lower end 42a of the first outer frame side wall 42 is not fixed by welding, etc. On the other hand, for the purpose of ensuring the strength and the rigidity of the sub- frame structure 1, the outer frame 40 and the inner frame 30 other than the first recess portion Rl are fixed by welding, etc.

In this embodiment, the inner frame 30 includes the second inner frame side wall 34 with a second recess portion R2 which is formed to recess downwardly at an upper end 34a of the second inner frame side wall 34. The second recess portion R2 is formed so as to be cut out in a substantially rectangular shape at an upper end portion of the second inner frame side wall 34 when viewed from the side of the inner frame 30.

Moreover, as well as the first recess portion Rl, to make it easier to bend the second inner frame side wall 34 and the second outer frame side wall 44 at the position of the second recess portion R2 when the impact is applied to the front of the sub-frame structure 1, the second recess portion R2 is included in the curved portion 3 of the left side arm 10.

Furthermore, as shown in FIG.2A and FIG.5B, the curved portion 3 includes a second deformation area D2 which is formed by a lower area D2a which is part of the second inner frame side wall 34 formed so as to protrude outward and curve, and an upper area D2b which is part of the second outer frame side wall 44 located above the lower area D2a of the second deformation area D2. Namely, the second deformation area D2 is an outside deformation area of the inner frame 30 and the outer frame 40.

As shown in FIG. IB, the first deformation area D1 is formed so that the degree of curvature of the first deformation are D 1 is larger than the degree of curvature of the second deformation area D2. Namely, the first deformation area D1 and the second deformation area D2 are formed so that the curvature radius of the curved surface indicating the first deformation area D 1 is smaller than the curvature radius of the curved surface indicating the second deformation area D2.

Therefore, in case that the impact is applied to the front of the sub-frame structure 1, the left side arm 10 bends so that the curvature of the first deformation region D1 is larger.

Furthermore, as well as the first recess portion Rl, for the purpose of surely controlling the deformation direction of the sub- frame, the second deformation area D2 includes the second recess portion R2.

As shown in FIG. 3, a lower end 44a of the second outer frame side wall 44 of the outer frame 40 is arranged to contact with the second recess portion R2 and to overlap with the second recess portion R2 when viewed from above. For the purpose of form a fragile portion, the second recess portion R2 and the lower end 44a of the second outer frame side wall 44 is not fixed by welding, etc. On the other hand, for the purpose of ensuring the strength and the rigidity of the sub-frame structure 1, the outer frame 40 and the inner frame 30 other than the second recess portion R2 are fixed by welding, etc.

Additionally, as shown in FIG.2A, FIG.2B, and FIG.4A to FIG.5B, the second recess portion R2 is arranged so as to face the first deformation area D 1. Thereby, even if there is only one deformation area in the left side arm 10, the first deformation D 1 area includes the first recess portion Rl which contacts with the lower end 42a of the first outer frame side wall 42, in case that the impact is applied to the front of the sub-frame structure 1, the left side arm 10 is easily bent at the first deformation area Rl.

Therefore, it is possible to surely control the deformation direction of the sub- frame structure 1 when the impact is applied to the front of the sub-frame structure 1.

Next, referring to FIG. 1A to FIG.5B, the operation of the sub- frame structure 1 will be provided. It is noted that light gray highlighted areas in FIG.2A to FIG. 5B represent the first deformation area D1 and the second deformation area D2 respectively, and dark gray highlighted areas in FIG. 2A to FIG. 5B represents an inner surface of the first recess portion Rl and an inner surface the second recess portion R2 respectively. (State before the impact is applied to the front of the sub-frame structure 1)

Firstly, in the state before the impact is applied to the front of the sub- frame structure 1, the first recess portion R1 is formed to recess downwardly at the upper end 32a of the first inner frame side wall 32 of the inner frame 30, as well as the lower end 42a of the first outer frame side wall 42 of the outer frame 40 is arranged to contact with the first recess portion R1 and to overlap with the first recess portion R1 when viewed from above. Moreover, the second recess portion R2 is formed to recess downwardly at the upper end 34a of the second inner frame side wall 34 of the inner frame 30, as well as the lower end 44a of the second outer frame side wall 44 of the outer frame 40 is arranged to contact with the second recess portion R2 and to overlap with the second recess portion R2 when viewed from above.

As such, the first recess portion R1 and the second recess portion R2 can function as elements which support the first outer frame side wall 42 and the second outer frame side wall 44 of the outer frame 40 from below, respectively. As a result, since it is not necessary to fix the recess portion of the inner frame 30 and the outer frame 40 by welding, etc. , fragile portions can be easily formed in the sub- frame structure 1 without adding any other elements in areas where the first recess portion R1 and the second recess portion R2 are arranged.

Next, since the outer frame 40 and the inner frame 30 other than the first recess portion R1 and the second are fixed by welding, etc. , it is possible to ensure the strength and the rigidity of the sub-frame structure 1.

(Case where the impact is applied to the front of the sub-frame structure 1)

Secondly, in this embodiment, the curved portion 3 includes the first deformation area D 1 and the second deformation area D2. The first deformation area D 1 is formed by a lower area D la which is part of the first inner frame side wall 32 formed so as to protrude outward and curve, and an upper area D lb which is part of the first outer frame side wall 42 located above the lower area Dla. The second deformation area D2 is formed by a lower area D2a which is part of the second inner frame side wall 34 formed so as to protrude outward and curve, and an upper area D2b which is part of the second outer frame side wall 44 located above the lower area D2a.

In case where the impact is applied to the front of the sub-frame structure 1, to absorb the impact applied to the front of the sub- frame structure 1 by further deforming the left side arm 10 toward the outside of the vehicle, the left side arm 10 bends so that the curvature of the first deformation region D1 is larger, the first inner frame side wall 32 and the first outer frame side wall 42 are easily bent at the first deformation area D 1 as well as the second inner frame side wall 34 and the second outer frame side wall 44 are easily bent at the second deformation area D2. As such, it is possible to control the deformation direction of the sub-frame when the impact is applied to the front of the sub-frame structure 1.

Furthermore, in this embodiment, the first deformation area D1 and the second deformation area D2 include the first recess portion R1 and the second recess portion R2, respectively. The first inner frame side wall 32 and the first outer frame side are surely bent at the position of the first recess portion R1 in the first deformation area Dl. The second inner frame side wall 34 and the second outer frame side are surely bent at the position of the second recess portion R2 in the second deformation area D2. As such, it is possible to more surely control the deformation direction of the left side arm 10 of the sub- frame structure 1 when the impact is applied to the front of the sub-frame structure 1.

Since it is possible to more surely control the deformation direction of the left side arm 10 of the sub- frame, the degree of the curvature of the curved portion 3 can be reduced. Therefore, not only the weight of the sub-frame structure 1 can be reduced by the first recess portion R1 and the second recess portion R2, but also the manufacturing processes and the manufacturing cost can be reduced by reducing the degree of the curvature of the curved portion 3, the first deformation area Dl and the second deformation area D2.

Therefore, the sub- frame structure 1, with a simple configuration, can easily form the fragile portion at the desired position and ensure the strength and the rigidity of the sub-frame, as well as can control the deformation direction of the left side arm 10 of the sub- frame when the impact is applied to the front of the sub-frame structure 1.

Since the pair of the left side arm 10 and the right side arm 20 are formed symmetrically with each other, the right side arm 20 operates in the same way as the left side arm 10.

In this embodiment, the first recess portion R1 in the first inner frame side wall 32 and the second recess portion R2 in the second inner frame side wall 34 are provided, but the present invention is not limited to this, and for example, one of the first recess portion R1 and the second recess portion R2 may be provided.

Although specific embodiments of the invention have been disclosed and described as well as illustrated in the companying drawings, it is simply for the purpose of better understanding of the principle of the present invention and it is not as a limitation of the scope and spirit of the teaching of the present invention. Adaption and modification to various structures such as design or material of the invention, mounting mechanism of various parts and elements or embodiments are possible and apparent to a skilled person without departing from the scope of the present invention which is to be determined by the claims. List of reference:

1 sub-frame structure

2 sub-frame body 2a rear edge

2b left side edge 2c right side edge 2d front edge 2e extending portion

3 curved portion 10 left side arm 20 right side arm 30 inner frame

32 first inner frame side wall 32a upper end

34 second inner frame side wall

34a upper end

36 base plate

40 outer frame

42 first outer frame side wall

42a lower end

44 second outer frame side wall

44a lower end

46 top plate

R1 first recess portion

R2 second recess portion

D 1 inside deformation area (first deformation area) Dla lower area Dlb upper area

D2 outside deformation area (second deformation area) D2a lower area D2b upper area

Claims

1. A sub-frame structure (1) for avehicle, which is attached to a vehicle body comprising: a sub-frame body (2); a left side arm (10) which is arranged to extend forward from said sub-frame body (2) and arranged at a left side in a vehicle width direction; and a right side arm (20) which is arranged to extend forward from said sub-frame body (2) and arranged at a right side in the vehicle width direction, wherein each of said left side arm (10) and said right side arm (20) includes an inner frame (30) and an outer frame (40) that is formed so as to cover said inner frame (30) from above, said inner frame (30) includes a first inner frame side wall (32), a second inner frame side wall (34) and a base plate (36), and said outer frame (40) includes a first outer frame side wall (42), a second outer frame side wall (44) and a top plate (46), wherein said inner frame (30) includes said second inner frame side wall (34) with a recess portion (R2) which is formed to recess downwardly at an upper end (34a) of said second inner frame side wall (34), and wherein a lower end (44a) of a second outer frame side wall (44) of said outer frame (40) is arranged to contact with said recess portion (R2) and to overlap with said recess portion (R2) when viewed from above.

2. The sub-frame structure (1) for a vehicle of claim 1, wherein each of said left side arm (10) and said right side arm (20) includes a curved portion (3) which are formed to curve toward the outside of said vehicle, wherein said curved portion (3) includes a first deformation area (Dl) formed by a lower area (Dla) which is part of said first inner frame side wall (32) formed so as to protrude outward and curve, and an upper area (Dlb) which is part of said first outer frame side wall (42) located above said lower area (Dla) of said first deformation area (Dl), wherein said curved portion (3) further includes a second deformation area (D2) formed by a lower area (D2a) which is a part of said second inner frame side wall (34) formed so as to protrude outward and curve, and an upper area (D2b) which is part of said second outer frame side wall (44) located above said lower area (D2a) of said second deformation area (D2), and wherein said recess portion (R2) is arranged so as to face said first deformation area

(Dl).

3. The sub- frame structure (1) for a vehicle of claim 2, wherein said first deformation area (D 1) includes another recess portion (Rl) which is formed to recess downwardly at said first inner frame side wall (32) of said inner frame (30).