JP4885912B2 - Car body rear structure - Google Patents

Description

  The present invention relates to a vehicle body rear part structure around a rear end of a rear frame that extends in the vehicle body longitudinal direction.

  This type of vehicle rear structure has been appropriately designed to protect the interior of the vehicle and absorb the collision load to reduce the impact on the vehicle body when subjected to a rear collision.

As such a vehicle body rear structure, a structure in which a gusset is provided at a joint portion between a rear frame and an extension is known (see, for example, Patent Document 1).
JP 2007-69736 A

However, the rear structure of the vehicle body is provided with a substantially triangular gusset in side view to reinforce between the lower surface of the rear frame and the extension of the extension extending below the lower surface of the rear frame. The strength of the gusset is too high, and the rear frame is bent at the time of a rear collision, so that the collision load cannot be sufficiently absorbed.
Further, in the vehicle body rear structure, for example, when the bumper beam height is different between the collision vehicle and the own vehicle, it is not possible to absorb the impact at the time of the collision.

  The present invention prevents the rear frame from being bent at the time of a rear collision, can stably buckle the gusset and the rear frame, and can absorb the shock, and can stably absorb the shock regardless of the height of the collision object. It is an object of the present invention to provide a vehicle body rear structure that can be used.

According to the first aspect of the present invention, in a vehicle body rear structure including left and right rear frames extended in the longitudinal direction of the vehicle body, the left and right rear frames are buckled at the time of a rear collision by reducing the strength at the rear than the front. Left and right gussets that expand the cross-section in a stepwise direction toward the rear are provided on the lower outside of these low-strength portions, and are attached to the left and right rear frames via extensions at the rear ends. A rear bumper beam, and a cross member that connects the rear ends of the left and right gussets below the extension. A wrinkle removal bead provided in a direction orthogonal to the direction, and a bend for forming wrinkle at least one front and rear in a bent line bent in a concave shape Characterized in that it comprises a polygonal line which is bent in the other concave without a.

The invention according to claim 2 is characterized in that a space convex portion separated from the rear frame is formed at a joint portion of the gusset to the rear frame.

The invention according to claim 3 is characterized in that the cross member is formed in an arc shape protruding upward when viewed from the back.

In the invention according to claim 1, the rear structure of the vehicle body includes left and right rear frames extending in the vehicle body longitudinal direction.
The left and right rear frames are formed with low-strength parts that are lower in strength than the front part at the rear and allow buckling in the event of a rear collision. The cross section is expanded stepwise toward the rear under these low-strength parts. The left and right gussets are provided so that, in the event of a rear collision, the gusset is buckled starting from the step-shaped recess regardless of the height at which the collision load is input, and the rear frame's low-strength parts are prevented from bending. can do. Further, at the time of a rear collision, the low strength portion of the rear frame can be buckled together with the gusset. That is, the entire frame composed of the gusset and the low strength portion is in the collapse mode. Therefore, the collision energy can be stably absorbed regardless of the height at which the collision load is input.

In addition, the left and right rear frames are equipped with rear bumper beams that are attached to the rear ends via extensions, and cross members that connect the rear ends of the left and right gussets are provided below the extensions. Even if it is lower than the rear frame and bumper beam, it can be received by the cross member.

The gusset includes a bent line bent into a concave shape, and a bead for forming wrinkle removal provided in the direction perpendicular to the vehicle longitudinal direction in the vicinity of the bent line bent into the concave shape. since with a polygonal line which is bent in the other concave without the one at molding wrinkle bead at least back and forth, it is possible to wrinkle during forming shape, at the time of rear-end collision of a cavity molding wrinkles bead Can promote the collapse of the gusset. As a result, it is possible to stabilize the collision absorbing action.

In the invention according to claim 2 , since the space convex portion that is separated from the rear frame is formed at the joint portion of the gusset to the rear frame, the gusset and the rear frame can be more easily buckled. As a result, the shock absorbing effect can be stabilized.

In the invention according to claim 3 , since the cross member is formed in an arcuate shape that protrudes upward when viewed from the back side, the difference in height is different when the collision object is lower than the rear bumper beam of the own vehicle. The range of application can be expanded.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals. In the figure, Fr is the front of the vehicle body, Rr is the rear of the vehicle body, L is the left side of the vehicle body, and R is the right side of the vehicle body.
1 is a perspective view of a vehicle body rear structure according to the present invention, FIG. 2 is a perspective view of a rear frame of the vehicle body rear structure according to the present invention, and FIG. 3 is a rear frame of the vehicle body rear structure shown in FIG. 4 is a cross-sectional view taken along line 4-4 of FIG.

  As shown in FIG. 1, the rear structure of the vehicle body includes left and right rear frames 12 and 12 extending in the longitudinal direction of the vehicle body, and extensions 13 attached to the rear ends of the left and right rear frames 12 and 12, respectively. 13, a rear bumper beam 14 passed to the rear ends of these extensions 13, 13, and a cross member 15 passed to lower portions of the rear ends of the left and right rear frames 12, 12.

  As shown in FIGS. 2 to 4, the rear frame (left rear frame) 12 includes a frame main body 23 that is divided into a front frame 21 and a rear frame 22 provided in front of the vehicle body, and the frame main body 23. And a gusset (left gusset) 24 joined to a lower rear portion of the gusset.

  The front frame 21 is a substantially U-shaped frame in sectional view, and the rear frame 22 is a substantially U-shaped frame in sectional view, and has a substantially U-shaped depth and a rear portion of the front frame 21. Rear end flanges 25 and 25 (one 25 is not shown) are formed to have substantially the same depth as the end and to which the extension 13 is attached at the rear end.

  That is, the frame body 23 is provided with a high-strength portion 28 having a front portion formed with high strength, and a rear portion formed with a low-strength portion 29 that has lower strength than the front portion and allows buckling at the time of a rear collision. The

  The gusset 24 is a substantially U-shaped member in cross-sectional view provided below the low-strength portion 29, and has a shape in which a substantially U-shaped cross section is enlarged in a stepwise direction toward the rear. , 42 (refer to FIG. 4 for 41) and a bottom surface portion 43 connecting the inner and outer side surface portions 41, 42.

  The gusset 24 reinforces the low-strength portion 29 of the rear frame 12 and prevents the low-strength portion 29 of the rear frame 12 from being bent when a load is applied from behind (collision occurs). In addition, the low-strength portion 29 of the rear frame 12 also functions to promote buckling and absorb the impact.

  The outer side surface portion 42 is formed with a joint portion 45 to be joined to the rear frame 12 in the vicinity of the opening 44 having a substantially U-shaped cross section, connected to the rear end flanges 25 and 25 of the rear frame 22 at the rear end, and the cross member 15. A gusset side flange 47 is formed to connect the two.

  The joint portion 45 is formed with a plurality of weld portions 48 and a space convex portion (a bulge portion) 49 bulged outwardly (separated from the rear frame 12) between the weld portions 48. That is, the space convex portion 49 serves to make the gusset 24 and the rear frame 12 easier to buckle when a rear collision occurs.

  Similarly to the outer side surface portion 42, the inner side surface portion 41 includes a joint portion including a plurality of welded portions (not shown) and a plurality of space convex portions, and a gusset side flange 46 (see FIG. 4).

The bottom surface portion 43 is a portion where the surfaces formed in a staircase shape are continuous. The bottom surface portion 43 is bent in a convex shape behind the first concave line portion 51 bent in a concave shape and the first concave line portion 51. The first convex bent line portion 54, the second concave bent line portion 52 bent concavely behind the first convex bent line portion 54, and the second concave bent line portion 52 bent backward convexly. Formed in the vicinity of the second convex broken line portion 55, the third concave bent line portion 53 bent concavely behind the second convex bent line portion 55, and the second concave bent line portion (folded line) 52, First to fourth beads 61 to 64 that are wrinkled during molding provided in a direction orthogonal to the vehicle front-rear direction and a lower flange 66 to which the cross member 15 is attached are formed.
In addition, the 1st-3rd recessed broken line parts 51-53 and the 1st, 2nd convex broken line parts 54 and 55 are broken lines which form step shape.

  The first and second beads 61 and 62 are formed in front of the second concave broken line portion (folded line) 52 and extended to the inner and outer side surface portions 41 and 42, and wrinkle at the time of forming the stepped portion. This bead is a bead for forming wrinkles, and the beads 61 and 62 also serve to give a trigger for crushing the gusset 24 at the time of a rear collision.

  The second and third beads 63 and 64 are formed behind the second concave broken line portion (folded line) 52, and, like the first and second beads, are formed wrinkles for removing wrinkles when forming the stepped portion. The bead 63 is a take-up bead, and the beads 63 and 64 also serve as triggers for crushing the gusset 24 at the time of rear collision.

The cross member 15 is formed in an arcuate shape that protrudes upward when viewed from the back surface, and is formed to be convex rearward in a plan view.
The cross member 15 is formed in a bow shape that protrudes upward when viewed from the back surface, so that the height range in which the vehicle body can be protected by the cross member 15 is wider than when the cross member 15 is formed in a straight shape. Can be covered.
Further, since the cross member 15 is formed to be convex rearward in a plan view, the energy at the time of collision can be efficiently transmitted to the gusset 24 as compared with the case where the cross member 15 is formed linearly.

FIGS. 5A to 5C are explanatory views showing loads acting on the vehicle body rear part structure shown in FIG.
In (a), in the vehicle body rear structure, the bottom surface of the gusset 24 is formed in a step shape. Therefore, when a rotational moment is applied to the rear bumper beam 14 as indicated by the arrow a1, the bottom surface portion 43 of the gusset 24 acts in the extending direction and can absorb the rotational moment. Further, when a rotational moment is applied to the rear bumper beam 14 as indicated by an arrow a2, the bottom surface portion 43 of the gusset 24 can act in the contraction direction to absorb the rotational moment.

  That is, the rear frame 12 does not bend and does not enter a folding mode in which energy cannot be absorbed, and the rear frame 12 enters a crushing mode and can absorb energy stably.

  In (b), when a load acts on the rear bumper beam 14 as shown by an arrow a3 from the rear of the vehicle body, the load acts on the rear frame 12 and the gusset 24 via the extension 13. Since the bottom surface portion 43 of the gusset 24 is formed in a stepped shape, the rear frame 12 is not bent and does not enter a folding mode in which energy cannot be absorbed, and the rear frame 12 is crushed so that energy can be absorbed. It can be transferred stably.

  In (c), when a load acts on the lower side of the rear bumper beam 14 as shown by the arrow a4 from the rear side of the vehicle body, the cross member 15 exists below the rear bumper beam 14, so that the gusset 24 passes through the cross member 15 from the rear side. Can be absorbed. Also in this case, the rear frame 12 is not bent and the folding mode in which energy cannot be absorbed is not entered, and the rear frame 12 is crushed and can be stably shifted to the collapse mode in which energy can be absorbed.

6A to 6C are explanatory views showing an example of deformation of the rear frame when a load is applied to the vehicle body rear structure shown in FIG.
In (a), the rear structure of the vehicle body before the load acts as shown by the arrow b1 from the rear of the vehicle body is shown.

  In (b), when the load acts from the rear side of the vehicle body as shown by the arrow b2, stress concentration occurs at the concave broken line portions 51 to 53 and the convex bent line portions 54 and 55 of the gusset 24, and these concave bent line portions 51 to 53 and the convex bent line are formed. The parts 54 and 55 are crushed.

  Further, in (c), when the load acts as shown by an arrow b3, crushing at the concave broken line portions 51 to 53 and the convex broken line portions 54 and 55 is promoted.

  As shown in FIGS. 1 to 3, the rear structure of the vehicle body has left and right rear frames 12, 12 extending in the longitudinal direction of the vehicle body, and extensions 13, at the rear ends of these left and right rear frames 12, 12. 13 is provided with a rear bumper beam 14 attached via 13.

  The left and right rear frames 12, 12 are formed with low strength portions 29, 29 that are lower in strength than the front portion and allow buckling in the case of a rear collision at the rear, and are rearwardly below these low strength portions 29, 29. Since the left and right gussets 24, 24 that expand the cross section in a stepwise direction are provided, the gussets 24, 24 can be divided into staircase-shaped concave portions (concave line portions) regardless of the height at which the collision load is input at the time of rear collision. 51 to 53) can be buckled from the starting point, and bending of the low strength portions 29, 29 of the rear frames 12, 12 can be prevented. Furthermore, the low strength portions 29 and 29 of the rear frames 12 and 12 can be buckled together with the gussets 24 and 24 at the time of rear collision. That is, the entire frame composed of the gussets 24, 24 and the low strength portions 29, 29 is in the collapse mode. Therefore, the collision energy can be stably absorbed regardless of the height at which the collision load is input.

  In addition, since the cross member 15 that connects the rear ends of the left and right gussets 24, 24 is provided below the extensions 13, 13, even when the rear bumper beam of the vehicle is lower than the rear bumper beam 14 of the own vehicle, It can be received by the cross member 15.

  As shown in FIG. 2, the gusset 24 is provided in the vicinity of the second concave broken line portion (folded line) 52 that expands the cross section in a stepped manner, and for forming wrinkles provided in a direction orthogonal to the collision direction. The bead 61 to 64 can be used to remove wrinkles when forming the stepped portion, and the bead 61 to 64 for removing the formed wrinkle can be used as a trigger for the gusset 24 to be crushed. it can.

  Since the space convex portion 49 that is separated from the rear frame 12 is formed at the joint portion 45 of the gusset 24 to the rear frame 12, the gusset 24 and the rear frame 12 can be more easily buckled. As a result, the shock absorbing effect can be stabilized.

  Since the cross member 15 is formed in an arcuate shape that protrudes upward when viewed from the back, when the collision object is lower than the rear bumper beam 14 of the own vehicle, the range of adaptation of the difference in height can be expanded. it can.

  Further, since the cross member 15 is formed to protrude rearward in a plan view, the energy at the time of collision can be efficiently transmitted to the gusset 24 with respect to the rear impact load.

  As shown in FIG. 4, the vehicle body rear structure according to the present invention is provided with first to third concave broken line portions 51 to 53 and first and second convex folded line portions 54 and 55 in a step shape. However, the number of steps is arbitrary.

  As shown in FIG. 4, the vehicle body rear portion structure according to the present invention is provided with the first to fourth beads 61 to 64 in the vicinity of the second recessed broken line portion (folded line) 52, but is not limited thereto. It does not preclude provision in the vicinity of other broken lines.

  As shown in FIG. 3, the rear structure of the vehicle body according to the present invention includes left and right gussets 24 and 24 having a stepwise rearwardly expanding section below the low strength portions 29 and 29 of the left and right rear frames 12 and 12, respectively. However, the present invention is not limited to this, and left and right gussets that expand the cross section in a stepwise manner toward the rear may be provided above the low-strength portions of the left and right rear frames.

  The vehicle body rear structure according to the present invention is suitable for use in passenger cars such as sedans and wagons.

1 is a perspective view of a vehicle body rear structure according to the present invention. It is a perspective view of the rear frame of the vehicle body rear structure according to the present invention. FIG. 3 is a side view of the rear frame of the vehicle body rear structure shown in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. It is explanatory drawing which shows the load which acts on the vehicle body rear part structure shown by FIG. It is explanatory drawing which shows a deformation | transformation of the rear frame in case a load acts on the vehicle body rear part structure shown by FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Rear frame, 13 ... Extension, 14 ... Rear bumper beam, 15 ... Cross member, 24 ... Gusset, 45 ... Joint part, 48 ... Welded part, 49 ... Space convex part, 51-53 ... Polygonal line (1st-3rd ), 54, 55, fold lines (first and second convex fold lines), 61-64, beads for forming wrinkles (first to fourth beads).

Claims (3)

In the vehicle body rear structure with left and right rear frames extended in the vehicle longitudinal direction,
The left and right rear frames are formed with low-strength portions that are lower in strength than the front portions and allow buckling in the event of a rear collision at the rear portions. Expanding left and right gussets are provided ,
The left and right rear frames are provided with rear bumper beams that are attached to rear ends via extensions, and a cross member that connects the rear ends of the left and right gussets is provided below the extensions.
The gusset includes a bent line bent into a concave shape, and a bead for forming wrinkles provided near the concave bent line and in a direction perpendicular to the vehicle longitudinal direction,
The rear structure of the vehicle body is characterized in that the bent line bent into a concave shape includes another bent line bent into a concave shape without the forming wrinkle removing bead one by one at the front and rear. The vehicle body rear part structure according to claim 1 , wherein a space convex portion spaced from the rear frame is formed at a joint portion of the gusset to the rear frame. The vehicle body rear part structure according to any one of claims 1 to 2 , wherein the cross member is formed in a bow shape protruding upward when viewed from the back.

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