JPH08282534A - Mounting structure of subframe for body to extension member - Google Patents

Abstract

PURPOSE: To prevent the horizontal section of an extension member from being bent and the like at the time of head-on collision with a vehicle by making the quantity of an off-set between the mounting position of a subframe to an extension member and an neutral axis at the horizontal section of the extension member, positioned in a range by which a specified formula is satisfied. CONSTITUTION: The quantity of an off-set between the mounting position of a subframe 22 to an extension member 21 and the neutral axis of a cross section at the horizontal section 21b of the extension member 21, is made to be L. When the section modulus of the horizontal section 21b of the extension member 21 is made to be Z, the cross sectional area of the horizontal section 21b of the extension member 21 is made to be A, the yielding stress of material used for the horizontal section 21b of the extension member 21 is made to be σy, and when input load to the horizontal section 21b from the subframe 22 is made to be P, the quantity L of an off-set shall be in a range by which a formula is thereby satisfied. By this constitution, the horizontal section 21b of the extension member 21 can thereby be prevented from being bent and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for attaching a subframe to an extension member in a vehicle.

[0002]

2. Description of the Related Art As a conventional device of this type, there is one shown in FIGS. 9 and 10, for example. In the figure, reference numeral 1 is a pair of front side members provided on both sides of the engine room E in the vehicle front-rear direction, and a rear end portion 1a of the front side member 1 is joined to a dash panel 2.

Further, an extension member 3 extending in the vehicle front-rear direction from the rear end 1a of the front side member 1 to the rear is connected. The extension member 3 has an inclined portion 3a and a horizontal portion 3b extending rearward from the inclined portion 3a and joined to the lower surface side of the floor panel 4, and has a hat-shaped cross section, and the flange portion has a floor portion. A closed cross section is formed by being joined to the panel 4 and the like.

The front side member 1 and the extension member 3 are provided with a sub-frame 6 for supporting a transverse link of the vehicle body suspension device. That is, this subframe 6
As shown in FIG. 10, is a length that extends over substantially the entire width in the vehicle width direction. The front end portions 6a at both ends in the vehicle width direction are attached to the downward extension portion 1b of the front side member 1 by bolts 7, The portion 6b is attached by a bolt 8 to the attachment surface portion 3c along the horizontal direction of the extension member inclined portion 3a.

At the time of a vehicle frontal collision, the front end side of the front side member 1 is crushed as shown in the figure to absorb the impact energy, and the engine / transmission 10 retracts. Then, the engine / transmission 10 interferes with the subframe 6 at the portion 11, and the input load from the mounting surface portion 3c of the extension member 3 via the subframe 6 becomes a main load flow, and the horizontal portion of the extension member 3 It is transmitted to 3b.

[0006]

However, in such a conventional device, the extension member 3 is used.
If the mounting surface 3c of the extension member 3 is located higher than the neutral shaft 12 of the horizontal portion 3b of the extension member 3 and the offset amount L from the mounting surface 3c to the neutral shaft 12 is large, a large bending moment is applied to the horizontal portion 3b of the extension member 3. Does not have any effect even if, for example, the vicinity of the mounting surface portion 3c is solidified by a reinforcement not shown in the drawing, and there is no effect in the horizontal portion 3b of the extension member 3 located further rearward, as shown by the chain double-dashed line in FIG. As a result, the reaction force of the extension member 3 is not sufficiently exerted, the retreat amount of the dash panel 2 becomes large, and the occupant living space at the time of collision may be reduced.

Therefore, the present invention prevents the extension member horizontal portion from being broken at the time of a vehicle frontal collision,
An object of the present invention is to provide a structure for attaching a subframe to an extension member that can effectively exert the reaction force of the extension member.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. In the invention described in claim 1, extension members are arranged in the vehicle front-rear direction along the lower portion of the vehicle body. The extension member is formed with an inclined portion that extends obliquely downward from the engine room side, and a horizontal portion that extends in a substantially horizontal direction from the lower portion of the inclined portion to the vehicle rear side under the floor panel. In a structure for mounting an extension member of a vehicle body subframe in which a subframe for supporting a vehicle body suspension device is attached to a mounting surface portion of an extension member inclined portion, a mounting position of the subframe to the extension member and a horizontal position of the extension member The amount of offset from the neutral axis of the section at the The section modulus of the horizontal portion of the member Z, the cross-sectional area of the horizontal portion of the extension member A,
When the yield stress of the material of the horizontal portion of the extension member is σy and the input load from the subframe to the horizontal portion is P, the offset amount L is within the range that satisfies the expression (1). .

[0009] According to a second aspect of the present invention, an extension member is arranged in the vehicle front-rear direction along the lower portion of the vehicle body, and the extension member has an inclined portion extending obliquely downward from the engine room side, and the inclination member is formed. A horizontal portion that extends in a substantially horizontal direction from the lower part of the section toward the rear of the vehicle under the floor panel is formed, and a subframe that supports a vehicle suspension device is attached to a mounting surface portion of the extension member inclined portion. In the attachment structure of the frame to the extension member, the rear end portion of the subframe is extended downward, the rear end surface of the extended portion is opposed to the front end surface of the horizontal portion of the extension member, and when the subframe is retracted, It is characterized in that the rear end surface of the rear end portion is set to abut on the front end surface of the horizontal portion.

According to a third aspect of the present invention, a recess is formed in the front end surface of the horizontal portion of the extension member to which the rear end surface of the subframe extension portion fits when the subframe retracts due to a vehicle frontal collision. It is characterized by being formed.

According to a fourth aspect of the present invention, the front end face of the horizontal portion of the extension member is arranged along the vertical direction.

[0012] The invention described in claim 5 is characterized in that a reinforcement for transmitting an input load from the front end portion to the floor panel is provided in the front end portion of the horizontal portion of the extension member.

According to a sixth aspect of the present invention, the attachment hole of the sub-frame attached to the attachment surface portion of the extension member inclined portion has an elongated hole shape extending substantially in the front-rear direction of the vehicle body, and is attached to the sub-frame at the time of a vehicle frontal collision. When a load is applied, the subframe slides substantially rearward through the mounting hole, and is set so as to interfere with the front end portion of the horizontal portion of the extension member.

[0014]

According to the invention described in claim 1, at the time of a vehicle frontal collision, the front end side of the front side member is crushed to absorb impact energy, and when the engine or the like moves backward, As a result of the interference, the input load from the attachment surface portion of the extension member becomes a main load flow via the sub-frame and is transmitted to the horizontal portion of the extension member.

At this time, since the offset amount L is set in the above range, the stress (P × L) / Z due to the bending moment acting on the horizontal portion due to the load P,
The combined stress with the stress P / A due to the axial force is equal to or lower than the yield stress σy. Therefore, the horizontal portion of the extension member can prevent the bending of the horizontal portion without increasing the section modulus Z of the extension member by increasing the plate thickness or the cross-sectional area, and the reaction force of the extension member can be kept high to the end. As a result, the retreat amount of the dash panel can be minimized to secure a wide occupant living space.

According to the invention described in claim 2, the rear end portion of the subframe is extended downward, and the rear end surface of the extended portion is
Face the front end face of the horizontal part of the extension member,
When the subframe is retracted, the rear end face of the rear end contacts the front end face of the horizontal part, so that the load input point from the subframe to the horizontal part is the rear end face that extends the subframe downward. Since it is lower than the conventional mounting point, the offset amount between the neutral axis of the extension member horizontal part and the load input point is small, and as a result, the bending load can be reduced, and the bending of the extension member can be suppressed as much as possible. The amount of retreat of the dash panel is further improved, and a wider cabin space can be secured in the event of a collision.

In this structure, compared with the conventional measures for reinforcing the horizontal portion of the extension member, it is only necessary to extend the subframe. Therefore, a far lighter measure can provide a sufficient effect and can reduce the cost. Connect

Particularly, in this structure, the position where the subframe is attached to the extension member (the position of the attachment surface portion) cannot be lowered in layout, and the offset satisfies the expression (1) of the invention of claim 1. This is effective when the amount L cannot be set.

According to the third aspect of the invention, the front end surface of the horizontal portion of the extension member is provided with a recess into which the rear end surface of the rear end portion of the sub frame fits when the sub frame retracts due to a vehicle frontal collision. By forming the sub-frame, when the vehicle frontal collision occurs, the sub-frame retracts, and when the sub-frame interferes with the horizontal portion of the extension member,
Since it fits into the concave portion of the front end surface of the horizontal portion, the escape due to sliding up, down, left and right is more reliably restrained. Therefore, since the load from the sub-frame can be effectively transmitted to the horizontal portion of the extension member, the load can be effectively beared at this horizontal portion.

According to the fourth aspect of the present invention, when the sub-frame retreats and interferes with the horizontal portion of the extension member at the time of a vehicle frontal collision, the rear end face of the sub-frame rear end along the vertical direction. However, since it abuts on the front end surface of the extension member horizontal portion along the vertical direction, the escape due to the vertical and horizontal sliding of the subframe is suppressed,
The reaction force of the extension member can be increased with respect to the load from the subframe.

According to the fifth aspect of the present invention, when the subframe retracts by a predetermined amount during a vehicle frontal collision, the extension portion of the rear end portion of the subframe collides with the front end portion of the extension member horizontal portion. . Then, because the force applied to the front end of the extension member can be dispersed by the reinforcement to a large area of the extension member and the floor panel, the reaction force of the extension member with respect to the sub-frame can be further increased. The retreat can be smaller.

Further, since the plate thickness of the front end portion of the extension member which interferes with the subframe becomes thicker due to the addition of the reinforcement, it is possible to prevent the front end portion of the extension member from being locally damaged by a large load from the subframe. it can.

According to the sixth aspect of the present invention, when a large load acts on the sub-frame at the time of vehicle collision, the sub-frame slides rearward of the vehicle through the elongated hole-shaped mounting hole. Therefore, since the subframe interferes with the front end face of the horizontal portion of the extension member without deforming the attachment surface portion that is the attachment portion of the subframe of the extension member, the horizontal portion has a large bending moment as in the conventional case. Does not act, the reaction force of the extension member does not cause the dash panel to retract.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.
The same or equivalent members as the conventional ones will be described with the same reference numerals.

First, the structure will be described. In the figure, reference numeral 1 is a pair of front side members provided on both sides of the engine room E in the vehicle front-rear direction.
The rear end portion 1 a is joined to the dash panel 2.

Further, an extension member 21 extending in the vehicle front-rear direction from the rear end 1a of the front side member 1 to the rear is connected. The extension member 21 includes an inclined portion 21a and an inclined portion 21a.
and a horizontal portion 21b extending rearward from a and joined to the lower surface side of the floor panel 4, and has a hat-shaped cross section,
The flange portion is joined to the floor panel 4 or the like to form a closed cross section.

The front side member 1 and the extension member 21 support a sub frame 2 for supporting a transverse link of a vehicle body suspension device.
2 are installed. That is, the sub-frame 22 has a length that extends over substantially the entire width in the vehicle width direction, and the front end portions 22a at both end portions in the vehicle width direction are attached to the downward extension portion 1b of the front side member 1 by the bolts 7 and the rear end portion. 22
b is attached by a bolt 8 to an attachment surface portion 21c of the extension member inclined portion 21a along the horizontal direction.

Then, the attachment position of the subframe 22 to the extension member 21 (the position of the attachment surface portion 21c) and the horizontal portion 21 of the extension member 21.
b, the amount of offset from the neutral axis 24 of the cross section at b, the section modulus of the horizontal portion 21b of the extension member 21 is Z, the cross sectional area of the horizontal portion 21b of the extension member 21 is A, and the horizontal portion 21 of the extension member 21.
When the yield stress of the material of b is σy and the maximum input load from the subframe 22 to the horizontal portion 21b is P, the offset amount L is set within the range that satisfies the expression (1).

[0030] Next, the operation will be described.

At the time of a frontal collision of the vehicle, the tip side of the front side member 1 is crushed to absorb the impact energy and the engine / transmission 10 retracts. Then, the engine / transmission 10 interferes with the subframe 22, and the input load from the mounting surface portion 21c of the extension member 21 becomes a main load flow through the subframe 22 and is transmitted to the horizontal portion 21b of the extension member 21. go.

At this time, if the offset amount L is set within the above range, the load P acting on the horizontal portion 21b
The combined stress of the stress due to the bending moment (P × L) / Z and the stress due to the axial force P / A is equal to or less than the yield stress σy. Therefore, the horizontal portion 21b of the extension member 21 can prevent bending of the horizontal portion 21b without increasing the section coefficient Z of the extension member 21 by increasing the plate thickness or the cross-sectional area, and the reaction force of the extension member 21 can be prevented. Since it can be maintained high until the end, the amount of retreat of the dash panel 2 can be minimized and a wide passenger living space can be secured.

FIG. 2 shows a second embodiment of the present invention.

In this embodiment, the shape of the sub-frame 32 is different from that of the first embodiment. That is, in the sub-frame 32, the rear end portion 32b is extended obliquely downward,
The rear end surface 32d of the extension portion 32c is opposed to the front end surface 21d of the horizontal portion 21b of the extension member 21,
The rear end surface 32d of the extension portion 32c is set so as to contact the front end surface 21d of the horizontal portion 21b when the subframe 32 retracts.

In this way, the load input point from the sub-frame 32 to the horizontal portion 21b becomes the rear end face 32d which is obtained by extending the sub-frame 32 downward, so that it is practically lower than the conventional attachment point and the extension. The offset amount between the neutral axis 24 of the member 21 and the load input point becomes small,
As a result, since the bending load can be reduced, the bending of the extension member 21 can be suppressed as much as possible, the retreat amount of the dash panel 2 can be further improved, and a wider cabin space at the time of collision can be secured.

In this structure, as compared with the measure for reinforcing the horizontal portion 21b of the extension member 21 based on the conventional structure, it is only necessary to extend the sub-frame 32, so that a much lighter measure can provide a sufficient effect. It leads to cost reduction.

Particularly, in this embodiment, the mounting position of the sub-frame 32 to the extension member 21 (mounting surface portion 2
(Position 1c) cannot be lowered in layout,
Offset amount L that satisfies the expression (1) of the first embodiment
This is effective when it cannot be set to.

FIG. 3 shows a third embodiment of the present invention.

FIG. 3 is a view of the sub-frame 42 as seen from below. A mounting hole 42c for inserting the bolt 8 is formed in the rear end portion 42b of the sub-frame 42.
Is formed in a long hole shape extending in the front-rear direction of the vehicle body.

According to this, when a large load is applied to the sub-frame 42 at the time of a vehicle collision, the sub-frame 42 slides rearward of the vehicle through the mounting hole 42c having a long hole shape as shown by a chain double-dashed line in the figure. To do. Therefore, the sub-frame 42 is not deformed without deforming the attachment surface portion 21c of the extension member 21, which is the attachment portion of the sub-frame 42.
Interferes with the front end face of the horizontal portion of the extension member 21. Therefore, a large bending moment does not act on the horizontal portion 21b as in the conventional case. Therefore, the reaction force of the extension member 21 causes the dash panel 2 to move.
Will not cause a setback.

Since the sub-frame 42 is movable in the horizontal direction and is constrained in the vertical direction, even if the front end surface 21d of the horizontal portion 21b of the extension member 21 has an oblique structure as in the conventional case, the sub-frame 42 is formed. It is possible to reliably input a load with a small offset amount from the neutral axis of the horizontal portion 21b of the extension member 21 to the horizontal portion 21b of the extension member 21 without escaping downward.

FIG. 4 shows a fourth embodiment of the present invention.

As shown in the second embodiment, in the sub-frame 32 of this embodiment, an extension 32c is formed at the rear end 32b, and the rear end face 32d of this extension 32c is the horizontal portion 21b of the extension member 21. Is opposed to the front end face 21d. The front end face 21d has a recess 21e having a size to fit the rear end face 32d of the extension portion 32c.
Are formed.

According to this, when the sub-frame 32 retreats and interferes with the horizontal portion 21b of the extension member 21 at the time of a frontal collision of the vehicle, the sub-frame 32 comes into the recess 21e of the front end face 21d of the horizontal portion 21b. Since they are fitted together, the escape due to sliding up, down, left and right is more reliably restrained. Therefore, the load from the sub-frame 32 can be effectively transmitted to the horizontal portion 21b of the extension member 21, so that the horizontal portion 21b can effectively bear the load.

FIG. 5 shows a fifth embodiment of the present invention.

In this embodiment, an extension portion 52e extending obliquely downward is formed at the rear end portion 52b of the subframe 52, and a rear end surface 52c of this extension portion 52e is formed along the vertical direction, while this rear end surface is formed. The front end face 21d of the horizontal portion 21b of the extension member 21 that faces 52c is also formed along the vertical direction.

When the sub-frame 52 retreats and interferes with the horizontal portion 21b of the extension member 21 at the time of a frontal collision of the vehicle, the rear end surface 52c of the rear end portion 52b of the sub-frame along the vertical direction has the extension member horizontal portion 21b. Since it abuts on the front end surface 21d along the vertical direction of the subframe 52, the escape due to the vertical and horizontal sliding of the subframe 52 is suppressed, and the reaction force of the extension member 21 against the load from the subframe 52 can be increased.

6 and 7 show a sixth embodiment of the present invention.

In this embodiment, the extension member 2
1 outside the front end of the horizontal portion 21b
4 is joined. This reinforcement 54 is shown in FIG.
As shown in, the cross section along the horizontal direction is U-shaped, and both side walls 54 a are joined to the extension member 21. The reinforcement 54 is formed with a front end face 54b along the vertical direction.

On the other hand, as in the fifth embodiment, the sub-frame 52 has an extension portion 52e extending obliquely rearward from the rear end portion 52b.
Is formed, and a rear end surface 52c is formed in the extension portion 52e along the vertical direction. When the subframe 52 retreats, the rear end surface 52c is formed on the front end surface 54b of the reinforcement 54 on the horizontal portion 21b side of the extension member 21. Abut.

In this way, by making the interference portion with the sub-frame 52 the reinforcement 54, for example, by making the plate thickness locally thicker than the general surface portion of the extension member 21, the sub-frame 52 from the sub-frame 52. The tip of the extension member 21 is not locally damaged by the heavy load.

FIG. 8 shows a seventh embodiment of the present invention.

In this embodiment, similarly to the second embodiment, the extension 32c is formed at the rear end 32b of the sub-frame 32, while the reinforcement 56 is formed in the front end of the horizontal portion 21b of the extension member 21. The extension member 21 and the floor panel 4 are joined and arranged.

According to this, when the sub-frame 32 retreats by a predetermined amount at the time of a frontal collision of the vehicle, the sub-frame 32 is
The extension portion 32c of the rear end portion 32b collides with the front end portion of the extension member horizontal portion 21b. Then, the force applied to the front end portion of the extension member 21 can be dispersed by the reinforcement 56 over a wide area of the extension member 21 and the floor panel 4.
Extension member 21 with respect to subframe 32
Because the reaction force of can be increased, dash panel 2
The retreat of can be made smaller.

Further, since the plate thickness of the front end portion of the extension member 21 which interferes with the sub-frame 32 becomes thicker due to the addition of the reinforcement 56, the front end portion of the extension member 21 is locally destroyed by the heavy load from the sub-frame 32. You can avoid that.

[0056]

As described above, according to the invention described in claim 1, since the offset amount L is set within a predetermined range, the stress due to the bending moment due to the load P (P × L) / Z and the stress P / A due to the axial force are equal to or less than the yield stress σy, the horizontal portion of the extension member has a section modulus Z of the extension member in order to increase the plate thickness and the sectional area. Bending of the horizontal part can be prevented and the reaction force of the extension member can be kept high to the end without increasing the size of the dash panel.

According to the invention described in claim 2, the rear end portion of the sub-frame is extended downward, and the rear end surface of the extended portion is
Face the front end face of the horizontal part of the extension member,
When the subframe is retracted, the rear end face of the rear end contacts the front end face of the horizontal part, so that the load input point from the subframe to the horizontal part is the rear end face that extends the subframe downward. Since it is lower than the conventional mounting point, the offset amount between the neutral axis of the extension member horizontal part and the load input point is small, and as a result, the bending load can be reduced, and the bending of the extension member can be suppressed as much as possible. The amount of retreat of the dash panel is further improved, and a wider cabin space can be secured in the event of a collision.

In this structure, compared with the conventional reinforcing structure for reinforcing the horizontal portion of the extension member, it is only necessary to extend the sub-frame. Therefore, a far lighter measure provides a sufficient effect and a cost reduction. Connect

Particularly, in this structure, the subframe mounting position (position of the mounting surface) on the extension member cannot be lowered in layout, and the offset satisfies the formula (1) of the invention of claim 1. This is effective when the amount L cannot be set.

According to the third aspect of the invention, the front end surface of the horizontal portion of the extension member is provided with a recess into which the rear end surface of the rear end portion of the sub frame fits when the sub frame retracts due to a vehicle frontal collision. By forming the sub-frame, when the vehicle frontal collision occurs, the sub-frame retracts, and when the sub-frame interferes with the horizontal portion of the extension member,
Since it fits into the concave portion of the front end surface of the horizontal portion, the escape due to sliding up, down, left and right is more reliably restrained. Therefore, the load from the sub-frame can be effectively transmitted to the horizontal portion of the extension member, so that the horizontal portion can effectively bear the load.

According to the fourth aspect of the present invention, when the sub-frame retracts and interferes with the horizontal portion of the extension member at the time of a vehicle frontal collision, the rear end face of the sub-frame rear end along the vertical direction. However, since it abuts on the front end surface of the extension member horizontal portion along the vertical direction, the escape due to the vertical and horizontal sliding of the subframe is suppressed,
The reaction force of the extension member can be increased with respect to the load from the subframe.

According to the fifth aspect of the present invention, when the sub-frame retracts by a predetermined amount during a vehicle frontal collision, the extension portion of the rear end portion of the sub-frame collides with the front end portion of the extension member horizontal portion. . Then, because the force applied to the front end of the extension member can be dispersed by the reinforcement to a large area of the extension member and the floor panel, the reaction force of the extension member with respect to the sub-frame can be further increased. The retreat can be smaller.

Further, since the plate thickness of the front end portion of the extension member which interferes with the subframe becomes thicker due to the addition of the reinforcement, it is possible to prevent the front end portion of the extension member from being locally damaged by a large load from the subframe. it can.

According to the sixth aspect of the present invention, when a large load is applied to the sub-frame at the time of vehicle collision, the sub-frame slides rearward of the vehicle through the long hole-shaped mounting hole. Therefore, since the subframe interferes with the front end face of the horizontal portion of the extension member without deforming the attachment surface portion that is the attachment portion of the subframe of the extension member, the horizontal portion has a large bending moment as in the conventional case. Since it does not act, the practical effect that the reaction force of the extension member does not cause the dash panel to retract.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the vehicle front-rear direction showing a first embodiment of the present invention.

FIG. 2 is a sectional view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 3 is a bottom view of the subframe portion of the vehicle body showing the third embodiment of the present invention.

FIG. 4 is a sectional view corresponding to FIG. 1 showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view corresponding to FIG. 1 showing a fifth embodiment of the present invention.

FIG. 6 is a sectional view corresponding to FIG. 1 showing a sixth embodiment of the present invention.

FIG. 7 is a sectional view taken along line AA of FIG. 6 showing the sixth embodiment.

FIG. 8 is a sectional view corresponding to FIG. 1 showing a seventh embodiment of the present invention.

FIG. 9 is a plan view showing a conventional example.

FIG. 10 is a sectional view taken along the vehicle front-rear direction showing the conventional example.

[Explanation of symbols]

 1 front side member 1a rear end 2 dash panel 4 floor panel 21 extension member 21a inclined part 21b horizontal part 21c mounting face 21d front end face 21e recess 22,32,42,52 subframe 22a front end 22b, 32b, 42b, 52b Rear end 32c, 52e Extension 32d, 52c Rear end face 24 Neutral shaft 54,56 Reinforce

Claims (6)

[Claims] 1. An extension member is arranged in the vehicle front-rear direction along a lower portion of a vehicle body, and the extension member has an inclined portion extending obliquely downward from the engine room side, and the extension member has a floor from a lower portion of the inclined portion. An extension member of a vehicle body subframe, in which a horizontal portion is formed that extends under the panel in a substantially horizontal direction toward the rear of the vehicle, and a subframe supporting the vehicle body suspension device is attached to a mounting surface portion of the extension member inclined portion. In the mounting structure described above, the offset amount between the mounting position of the subframe to the extension member and the neutral axis of the cross section of the extension member in the horizontal portion is L, the section modulus of the horizontal portion of the extension member is Z, and the extension member is The cross-sectional area of the horizontal part of A is When the yield stress of the material of the horizontal portion of the torsion member is σy and the input load from the subframe to the horizontal portion is P, the offset amount L is within the range that satisfies the expression (1). Attachment structure for subframe extension members. 2. An extension member is arranged in the vehicle front-rear direction along a lower portion of a vehicle body, and the extension member has an inclined portion extending obliquely downward from the engine room side, and the extension member has a floor from a lower portion of the inclined portion. An extension member of a vehicle body subframe, in which a horizontal portion is formed that extends under the panel in a substantially horizontal direction toward the rear of the vehicle, and a subframe supporting the vehicle body suspension device is attached to a mounting surface portion of the extension member inclined portion. In the mounting structure of, the rear end portion of the subframe is extended downward, the rear end surface of the extended portion is opposed to the front end surface of the horizontal portion of the extension member, and when the subframe is retracted, the rear end portion The rear end surface is set so as to contact the front end surface of the horizontal portion. Mounting structure of the box tension member. 3. A front end surface of a horizontal portion of the extension member is formed with a recess into which a rear end surface of the sub frame extension portion fits when the sub frame retracts due to a vehicle frontal collision. The structure for attaching the vehicle body subframe to the extension member according to item 2. 4. A front end face of a horizontal portion of the extension member is arranged along a vertical direction.
Attachment structure for the vehicle body subframe described above to the extension member. 5. A reinforcement for transmitting an input load from the front end portion to a floor panel is provided in a front end portion of a horizontal portion of the extension member, according to any one of claims 2 to 4. Attachment structure for the vehicle body subframe described above to the extension member. 6. The mounting hole of the sub-frame mounted on the mounting surface portion of the extension member inclined portion has a long hole shape extending substantially in the front-rear direction of the vehicle body, and when a load is applied to the sub-frame during a vehicle frontal collision, the sub-frame is mounted. The vehicle body according to any one of claims 2 to 5, wherein the frame is set to slide substantially rearward through the mounting hole so as to interfere with a front end portion of a horizontal portion of the extension member. Attachment structure for subframe extension members.