JP2002029342A - Rear bumper structure for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an impact load in rear face collision input substantially straightly to a side frame, in a rear bumper for a vehicle having a layout where the rear bumper attached to the side frame is offset downwards with respect to the side frame. SOLUTION: A rear bumper beam 3 is constituted into structure having a general cross-section part 31 serving as a beam body, and an expanded cross- section part 32 of which a cross-section is expanded upwards and rearwards in an attaching portion of the cross-section part 31 onto the side frame 1, the cross-section part 31 serving as the beam body is brought into the layout offset downwards with respect to the side frame 1 in a condition where the expanded cross-section part 32 is attached to the side frame 1, the collision load in the rear collision is input from a rear face part 32a of the expanded cross-section part 32 where a vertical-directional offset to the side frame is zero or minimum, the load is transmitted substantially straightly to the side frame 1, and impact energy is effectively absorbed by axial-directional buckling of the side frame 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rear bumper structure.

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 7-4208, a rear bumper of a vehicle is mounted and supported on the rear ends of left and right side frames fixed to the lower surface of a rear floor. That is, it is common to attach the bumper beams of the rear bumper directly or via bumper stays to the rear ends of the left and right side frames.

[0003] The above-mentioned side frames are designed to reduce the weight of the vehicle body and to ensure the effect of absorbing the impact energy in the event of a rear collision.
It is desirable to arrange them straight in the front-rear direction.

[0004] When the side frame is straightened in this way, the side frame is arranged as high as possible as high as possible in order to secure a load clearance for a rear suspension, a rear differential, a muffler, a fuel tank, and the like attached to a lower portion of the rear floor. Is desirable. However, from a practical point of view such as a light collision requirement and the convenience of the rear luggage compartment, it is desirable that the rear bumper is arranged at a low position substantially along the lower edge of the rear skirt.

[0005] As described above, if the two conditions, that is, the side frame is installed at a high position above and the rear bumper is installed at a low position, are simultaneously satisfied, for example, as shown in FIG. As described above, the vertical offset amount δ between the side frame a and the rear bumper beam b attached to the rear end of the side frame a via the extension c and the bump stay d must be large.

In FIG. 7A, e indicates a rear skirt box.

[0007]

In the conventional structure having a large vertical offset amount δ between the side frame a and the rear bumper beam b as described above, when a collision load is input to the rear bumper beam b, as shown in FIG. As shown in the figure, the downward bending force increases, and the side frame a becomes the bending deformation mode, so that it is difficult to secure the desired deformation mode (axial buckling deformation mode), and it is difficult to obtain the impact energy absorbing effect. , There is a problem.

An object of the present invention is to solve the above conventional problems.

[0009]

SUMMARY OF THE INVENTION The present invention provides an enlarged cross-sectional portion which is at least upwardly enlarged at a portion where a general cross-sectional portion forming a beam body of a rear bumper beam and extending in a vehicle width direction is attached to a side frame. By forming this enlarged cross-section as a mounting part to the side frame, the beam main body is mounted in a state where the rear bumper beam is mounted on the side frame at the mounting part where the vertical offset with respect to the side frame is zero or minimal. It is possible to make a layout in which the general cross-section to be formed is offset downward with respect to the side frame.

Also, the rear bumper beam has an enlarged cross-sectional shape which is extended rearward of the general cross-section, so that the collision load at the time of a rear collision has zero or minimal offset in the vertical direction with respect to the side frame. The input from the rear part of the enlarged cross section is transmitted almost straight to the side frame, so there is almost no bending force, the side frame buckles and deforms according to the set deformation mode, and effective impact energy Is absorbed.

Further, by forming a substantially horizontal partition surface in the cross section of the rear bumper beam in accordance with the height of the lower surface of the side frame, transmission of the collision load to the side frame is further improved. Further, the rear bumper beam is attached to the side frame via the bumper stay, and the front portion of the portion of the rear bumper beam offset downward from the side frame and the lower surface portion of the bumper stay are joined by a gusset, thereby providing a rear bumper beam. In response to a load input to the lower part of the beam, the load is smoothly transmitted from the lower surface of the bumper stay to the lower surface of the side frame by the gusset.

Furthermore, a front wall surface which is substantially linear in the vehicle width direction in a plan view and a rear wall surface having an inclined surface inclined obliquely forward are provided in a predetermined range of the left and right ends of the rear bumper beam. Thus, the rear bumper can sufficiently cope with the rear oblique collision.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a first embodiment of the present invention. Reference numeral 1 denotes left and right side frames fixed to the lower surface of a rear floor and extending in the longitudinal direction of the vehicle body. The rear bumper 2 serves as a vehicle body reinforcing member, and a rear bumper beam 3 for efficiently transmitting and dispersing a collision load to the right and left of the vehicle body in a rear collision, and a bumper face 4 as an external component covering the rear bumper beam 3. It is composed of The rear bumper 2 is mounted and supported on the left and right side frames 1 by fixing the rear bumper beam 3 to the rear end portions of the left and right side frames 1 via the extension 5 and the bump stay 6. Reference numeral 7 denotes a rear skirt box.

The rear bumper beam 3 has a substantially rectangular cross-section and forms a beam main body, and a cross-sectional shape obtained by extending and expanding the general cross-section 31 upward and rearward at the mounting portions to the left and right side frames 1. And a metal material such as a synthetic resin material or an aluminum alloy. At the rear end of the extension 5 fixed to the rear end of the side frame 1 by welding or the like, the upper front surface 32a of the left and right enlarged cross sections 32 of the rear bumper beam 3 is vertically offset from the side frame 1. By fixing the rear bumper beam 6 to the rear bumper beam 3 without using the bumper stay 6, the general cross section 31 forming the beam main body is offset downward from the side frame 1.
By attaching a synthetic resin bumper face 4 from the rear side of the vehicle, the rear bumper 2 can be arranged at a low position substantially along the lower edge of the rear skirt box 7.

When the rear bumper 2 is mounted as described above, the rear surface 32b of the enlarged cross section 32 of the rear bumper beam 3 projects rearward from the rear of the general cross section 31. Are input to the rear bumper beam 3 from the rear surface portion 32b of the left and right enlarged cross-sectional portions 32. Since the rear surface portion 32b of the enlarged cross-sectional portion 32 has almost zero or minimal offset with respect to the side frame 1, a bending force hardly occurs due to the input of a collision load, and the input load is applied by the general cross-sectional portion 31 forming the beam body. The load is distributed to the left and right side frames 1 and transmitted straight to the side frames 1, and the side frames 1 are buckled and deformed substantially in the axial direction (front-rear direction) so that effective impact energy is absorbed.

FIGS. 2A and 2B show a second embodiment of the present invention. In this embodiment, when the cross-sectional height of the enlarged cross-sectional portion 32 of the rear bumper beam 3 cannot be sufficiently taken, that is, This is a countermeasure in a case where the cross-sectional height of the enlarged cross-sectional portion 32 cannot be sufficiently taken to make it difficult to transmit a sufficient load to the side frame 1. A substantially horizontal partition surface 33 connecting the front portion and the rear portion is provided. The configuration other than the partition surface 33 is substantially the same as that of the first embodiment. In FIG. 2, the same reference numerals as those in FIG. 1 represent the same portions as those in FIG.

As described above, by providing the partition surface 33 in the rear bumper beam 3 which communicates with the lower surface portion 1a of the side frame 1 in a substantially straight line in a side view, the side frame 1
The transmission of the collision load to the lower surface portion 1a of the side frame 1 is further improved, and the desired deformation mode of the side frame 1 and the effect of absorbing the impact energy can be ensured.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, the entire rear bumper beam 3 forms a beam main body having the same cross section and a general cross section 31 and an enlarged cross section 3.
2 and a key-shaped cross-section 320 corresponding to the shape of the extended and enlarged portion extending upward and rearward are separately formed, and the key-shaped cross-sections 320 are combined at appropriate positions on the left and right of the general cross-section 31. Thus, a portion corresponding to the enlarged cross-sectional portion 32 of the first and second embodiments is formed. The key-shaped cross-sectional portion 320 and the general cross-sectional portion 31 are attached to the rear end of the side frame 1 via the bumper stay 6. It is designed to be installed without vertical offset. In the general cross section 31, a substantially horizontal partition surface 33 for vertically dividing the cross section is formed integrally.

With the above construction, the general cross-section portion 31 forming the beam main body is mounted so as to be offset below the side frame 1, and a synthetic resin bumper face is attached to the rear bumper beam 3 from the rear side of the vehicle. By mounting, the rear bumper can be arranged at a predetermined low position, and the general cross section 3
1 is substantially linearly connected to the lower surface portion 1a of the side frame 1 in a side view, so that the collision load input from the rear surface portion 320b of the key-shaped cross-section portion 320 at the time of a rear surface collision can be reduced by the general cross section forming the beam main body. The load is transmitted to the side frame 1 almost straight while being distributed to the left and right side frames 1 by the portion 31, and the effective buckling deformation of the side frame 1 allows effective absorption of impact energy.

According to the third embodiment, the general cross section 3
1 and the key-shaped cross section 320 are separately formed, so that both can be formed by extrusion molding of a metal (aluminum alloy or the like), thereby not only reducing the manufacturing cost but also reducing the general cross section 31 and the key. There is an advantage that the mold cross section 320 can be formed of a different material according to each function.

FIG. 4 shows a fourth embodiment of the present invention. In attaching the rear bumper beam 3 shown in FIG. 3 to the bumper stay 6, the lower part of the front part of the general cross section 31 constituting the beam main body and the bumper stay A gusset 8 having a substantially triangular cross-section is provided between the gusset 8 and the lower surface of the rear bumper beam 3. The effect that the gusset 8 can be transmitted smoothly from the lower surface of the bumper stay 6 to the lower surface 1a of the side frame 1 is provided.

Incidentally, in each of the embodiments shown in FIGS. 1 and 2,
The configuration of FIG. 4 in which the gusset 8 is provided between the lower part of the front part of the general cross-section part 31 and the lower part of the bumper stay 6 can be applied.

In the second to fourth embodiments, the state where the extension 5 is omitted and the bumper stay 6 is directly attached to the rear end of the side frame 1 is shown. Side frame 1 as in the embodiment
The extension 5 is fixed to the rear end by welding or the like,
The bumper stay 6 may be attached to the rear end of the extension 5. Conversely, in the first embodiment of FIG. 1, the extension 5 may be omitted, and the front end of the bumper stay 6 may be directly attached to the rear end of the side frame 1.

FIG. 5 shows a fifth embodiment of the present invention. This embodiment is applicable to all of the rear bumper beams 3 shown in the first to fourth embodiments.

That is, an inclined surface 34 having a rear wall surface inclined diagonally forward is formed in a predetermined range of the left and right ends of the rear bumper beam 3 shown in each of the first to fourth embodiments. The front wall surface of the rear bumper beam 3 is substantially linear in the vehicle width direction in a plan view, so that a predetermined clearance is secured between the front wall surfaces of the right and left ends of the rear bumper beam 3 and the rear surface of the vehicle body. In FIG.
Structures other than the inclined surface 34 are the same as those in FIGS. 1 to 4, and the same reference numerals as those in FIGS. 1 to 4 denote the same parts as those in FIGS. 1 to 4.

Since the inclined surfaces 34 are formed on the rear wall surfaces of the left and right end portions of the rear bumper beam 3 in this manner, it is possible to cope with a rear oblique collision, and the front wall surfaces of the left and right end portions of the rear bumper beam 3 and the rear surface of the vehicle body. And a predetermined clearance between them, it is possible to secure a stroke range that does not interfere with the rear surface of the vehicle body at both ends of the rear bumper beam 3 in the event of a rear oblique collision.

The rear bumper beam 3 shown in FIG. 5, for example, as shown in FIG.
A predetermined range of the left and right ends of the general cross-section 31 forming the beam main body is bent forward by a predetermined angle to form an inclined surface 34 on the rear wall surface, and a front portion of the bent portion (hatched portion is hatched). By cutting the (part) 35, the front wall surface is made substantially linear in plan view over the entire region in the vehicle width direction, so that it can be easily and easily manufactured.

[0029]

As described above, according to the present invention, the rear bumper is arranged to be offset downward with respect to the left and right side frames fixed to the lower surface of the rear floor.
In addition to ensuring sufficient load clearance for the rear suspension, rear differential, muffler, fuel tank, etc. mounted on the lower part of the rear floor, the height of the rear bumper should meet the practical requirements of light collision requirements and the convenience of the rear luggage compartment. In the above, an enlarged cross-sectional portion in which the cross-section is extended at least upwardly at the mounting portion of the general cross-sectional portion forming the beam main body of the rear bumper beam to the side frame is formed, and the expanded cross-sectional portion is used as a mounting portion to the side frame. This makes it possible to mount the rear bumper beam to the side frame at a mounting portion where the vertical offset with respect to the side frame is zero or extremely small.

Further, the rear bumper beam has a cross-sectional shape that is extended and expanded to the rear of the general cross-section, so that the collision load at the time of a rear-side collision is such that the vertical offset with respect to the side frame is zero or minimal. The input from the rear part of the enlarged cross section is transmitted almost straight to the side frame, so there is almost no bending force, the side frame buckles and deforms according to the set deformation mode, and effective impact energy Is absorbed.

Further, by forming a substantially horizontal partition surface within the cross section of the rear bumper beam in accordance with the height of the lower surface of the side frame, transmission of the collision load to the side frame is further improved.

Further, a gusset is provided between a front surface of a portion of the rear bumper beam offset below the side frame and a lower surface of the bumper stay in a state where the rear bumper beam is mounted on the side frame via the bumper stay. In response to a load input to the lower part of the rear bumper beam, the load is smoothly transmitted from the lower part of the bumper stay to the lower part of the side frame by the gusset, and the impact energy is effectively absorbed.

Further, in a predetermined range of the left and right ends of the rear bumper beam, a front wall surface which is substantially linear in the vehicle width direction in a plan view and a rear wall surface having an inclined surface inclined obliquely forward are provided. As a result, the rear bumper can sufficiently cope with the rear oblique collision, and can bring about a great effect in practical use, in combination with the simple overall structure and low cost. .

[Brief description of the drawings]

1A and 1B show a first embodiment of the present invention, in which FIG. 1A is an exploded perspective view of a rear portion of a vehicle body and a rear bumper beam attached thereto, and FIG. 1B is a cross-sectional view taken along a line BB of FIG. (C) is a CC sectional view of (A), and (D) is a DD sectional view of (A).

FIGS. 2A and 2B are cross-sectional views of a rear bumper beam mounting portion according to a second embodiment of the present invention.

3A and 3B show a third embodiment of the present invention, in which FIG. 3A is a sectional view of a rear bumper beam mounting portion, and FIG. 3B is an exploded perspective view of a main part of the rear bumper beam shown in FIG.

FIG. 4 is a sectional view of a rear bumper beam mounting portion showing a fourth embodiment of the present invention.

FIG. 5 shows a fifth embodiment of the present invention, and is a plan view of a side frame and a rear bumper attached thereto, showing a relationship between a rear bumper beam and a rear surface of a vehicle body.

FIG. 6 is an explanatory perspective view of a relevant part showing an example of a method of manufacturing the rear bumper beam shown in FIG. 5;

FIG. 7 is a view showing a conventional example of a rear bumper beam, and FIG.
FIG. 4 is a cross-sectional view of a rear bumper beam mounting portion, and FIG. 4B is a cross-sectional view illustrating a deformed state when a collision load is input.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Side frame 1a Lower surface part 2 Rear bumper 3 Rear bumper beam 31 General sectional part 32 Enlarged sectional part 320 Key type sectional part 32a Front part 32b Rear part 33 Partition surface 34 Inclined surface 4 Bumper face 5 Extension 6 Bumper stay 7 Rear skirt box 8 Gusset

Claims (6)

[Claims] 1. A rear bumper beam extending in a vehicle width direction for connecting the left and right side frames to a rear end portion of the left and right side frames extending in a vehicle front-rear direction. A structure having a general cross-section extending in the vehicle width direction forming a beam main body, and an enlarged cross-section extending and expanding the cross-section at least upward at a mounting portion of the general cross-section to the side frame, A rear bumper structure for a vehicle, wherein the enlarged cross-section is attached to the rear end of the side frame so that the general cross-section forming the beam main body has a layout that is offset downward with respect to the side frame. 2. The rear bumper structure for a vehicle according to claim 1, wherein an enlarged cross-section provided at a portion of the general cross-section of the rear bumper beam attached to the side frame has a cross-section extending and expanding upward and rearward. When the enlarged cross-section is attached to the rear end of the side frame, the vertical offset between the side frame and the rear surface protruding rearward of the enlarged cross-section is configured to be zero or minimal. A rear bumper structure for a vehicle. 3. A rear bumper beam of a rear bumper extending in a vehicle width direction for connecting the left and right side frames to a rear end portion of the left and right side frames extending in a vehicle front-rear direction. A general cross-section extending in the vehicle width direction with the same cross-sectional shape to form a beam main body, and left and right forming enlarged cross-sections that bulge upward and rearward in combination with a mounting portion of the general cross-section to the side frame. The cross section of the beam main body is formed by attaching the enlarged cross section formed by combining the general cross section with the key cross section to the rear end of the side frame. In contrast, the layout is offset downward, so that the vertical offset between the rear surface of the key-shaped cross section and the side frame is zero or minimal. A rear bumper structure for a vehicle. 4. The rear bumper structure for a vehicle according to claim 1, wherein a substantially horizontal partition surface is provided in a cross section of the rear bumper beam, and the partition surface is provided when the rear bumper beam is attached to a side frame. A rear bumper structure for a vehicle, characterized in that the lower surface of the side frame and the lower surface of the side frame are located on substantially the same straight line in a side view. 5. The rear bumper structure for a vehicle according to claim 1, wherein the rear bumper beam is attached to a side frame via a bumper stay, and a front surface of a portion of the rear bumper beam offset below the side frame. A rear bumper structure for a vehicle, wherein a gusset is connected between a lower portion of the bumper stay and a lower portion of the bumper stay. 6. The rear bumper structure for a vehicle according to claim 1, wherein a front wall surface of the rear bumper beam is substantially linear in a vehicle width direction in a plan view, and predetermined positions of right and left ends of the rear wall surface are provided. A rear bumper structure for a vehicle, wherein a range portion is formed on an inclined surface inclined diagonally forward.