JP6612094B2 - Car body rear structure - Google Patents

Description

  The present invention relates to a vehicle body rear structure, and more particularly to a vehicle body rear structure in which a cross member is bridged between side frames extending in the front-rear direction along both sides of the vehicle body rear part.

  Conventionally, left and right side frames extending in the front-rear direction along both sides of a floor panel are provided at the rear of a vehicle body such as an automobile, and a cross member is bridged between the left and right side frames. Rear wheel suspensions are connected to the left and right side frames.

  The cross member that connects the left and right side frames is a member that contributes to the rigidity and strength of the vehicle body, and mainly supports the side frame bending and torsional behavior from the vehicle width direction to suppress displacement of the side frame. The impact load that is repeatedly input from the suspension to the side frame as the vehicle travels is distributed and transmitted throughout the vehicle body.

  Patent Documents 1 and 2 are known as vehicle body structures that ensure the rigidity of a side frame to which a load from this type of suspension is input.

  As shown in the plan view of the main part in FIG. 9, the vehicle body structure of Patent Document 1 is connected to the left and right side frames 101 by bending both ends 102a of the cross member 102 forward and connecting the cross member 102 and the side frame 101 to each other. Are connected by an auxiliary member 103 extending obliquely with respect to the front-rear direction. A bracket 104 is attached to a substantially triangular region surrounded by three members of the end portion 102 a of the cross member 102, the side frame 101, and the auxiliary member 103, and a suspension shock absorber 105 is attached to the bracket 104.

  As a result, the input load from the shock absorber 105 is distributed and transmitted to the three members of the auxiliary member 103, the cross member 102, and the side frame 101 via the bracket 104, and deformation modes such as bending and twisting of the side frame 101 are suppressed. The

  As shown in a perspective view of a main part in FIG. 10, the vehicle body structure of Patent Document 2 includes left and right side frames 111 and a suspension for a rear wheel that extends in the vehicle width direction and is connected to the left and right side frames 111. And a cross member 113 that connects the left and right side frames 111 at positions corresponding to the suspension member 112, and at both ends of the cross member 113 in the front-rear direction at connecting portions with the side frame 111. An enlarged portion 113a is provided.

  According to this configuration, the joint area between the side frame 111 and the enlarged portion 113a is increased by the enlarged portion 113a enlarged in the front-rear direction, and the load transmitted from the side frame 111 to the cross member 113 is dispersed and transmitted at the connection portion. Thus, the stress is not locally concentrated by the enlarged portion 113a, and the installation portion of the suspension member 112 can be reinforced.

Japanese Patent No. 5353372 JP-A-8-142909

  According to Patent Document 1, a bracket 104 is attached to a substantially triangular region surrounded by an end 102 a bent to the front side of the cross member 102, the side frame 101, and the auxiliary member 103, and a shock absorber 105 is attached to the bracket 104. As a result, the load from the shock absorber 105 is distributed and transmitted to each member of the auxiliary member 103, the cross member 102, and the side frame 101, and deformation of the side frame 101 is suppressed.

  On the other hand, suspension members other than the shock absorber 105 are also supported on the side frame 101, and there is a concern about the behavior of the side frame 101 such as torsion and breakage due to the suspension load being input from these suspension members to the support portion. If a stiffening member or the like for stiffening the support portion or the like is separately provided, the configuration becomes complicated and there is a concern about an increase in the weight of the vehicle body.

  According to Patent Document 2, the suspension member 112 of the side frame 111 is installed by having an enlarged portion 113a that expands in the front-rear direction at the end of the cross member 113 at a position corresponding to the joint between the side frame 111 and the suspension member 112. The part is reinforced.

  On the other hand, suspension members other than the suspension member 112 are also supported on the side frame 111, and suspension loads are input from these suspension members, and there is a concern about the behavior of the side frame 101 such as twisting and bending. If a stiffening member or the like for stiffening the support portion or the like is separately provided, the configuration becomes complicated.

  Accordingly, an object of the present invention made in view of such a point is to provide a vehicle body rear structure in which the behavior of the side frame with respect to suspension load input is suppressed with a simple configuration.

Car body rear portion structure that to achieve the above object, the right and left pair of side frames extending in the longitudinal direction along the rear portion of the vehicle body on both sides, in the vehicle rear body structure at both ends of the cross member extending in the vehicle width direction are connected, Formed at both ends of the cross member is an enlarged portion that expands in the front-rear direction as it moves toward the side frame, and the front edge region and the rear edge region of the enlarged portion extend toward different suspension attachment portions. It is characterized by doing.

  According to this structure, an effective joint area with the side frame is secured by having the enlarged portions expanding in the front-rear direction at both ends of the cross member coupled to the left and right side frames, and a load is transmitted from the side frame to the cross member. Load is distributed and transmitted at the connection point, and the stress is not concentrated locally by the enlarged part, but is transmitted to the cross member, and the front edge area and the rear edge area of the enlarged part are attached to the suspension. The load applied to the suspension mounting part is efficiently distributed and transmitted to the entire vehicle body via the cross member with a simple structure extending toward the part, and the load acting on the side frame is greatly reduced, and the side frame is twisted. Behaviors such as breakage and folding are suppressed, and improvement in vehicle handling stability can be ensured.

In addition , at least one of the front edge region and the rear edge region of the enlarged portion extends toward a frame bending portion where the side frame is curved.

  According to this structure, the load acting on the frame bending portion, which is bent on the side frame and is concerned that the side frame is bent when the load is input, is applied to the vehicle body via the cross member. The entire frame is distributed and transmitted, the load of the frame bending portion is reduced, and the behavior of the frame bending portion such as twisting and bending is suppressed.

Further, the front edge region, front cross member continuous in the vehicle width direction in a U shape with a front lower surface and front side front and front rear surfaces formed bent along the leading and trailing edges of the lower surface The rear edge region is a U-shaped cross-section having a rear lower surface and a rear front surface and a rear surface bent along the front and rear edges of the rear lower surface in the vehicle width direction. An extended rear cross member portion, wherein the front rear surface and the rear front surface are joined together via a connecting portion extending in the vehicle width direction, and the front cross member portion and the rear side are moved toward the end portion. the cross member portion is branched in the longitudinal direction, the side flanges after being bent form the bent formed front flange and a rear surface to the front surface is bonded to the floor panel, and the connecting portion is attached to the floor panel It is characterized by.

  According to this structure, the front side edge region of the cross member is formed by a front cross member portion that is U-shaped in cross section and continues in the vehicle width direction, and the rear edge region is formed in a U shape and extends in the vehicle width direction. A front flange formed by a rear cross member portion and bent at the front surface and a rear flange bent at the rear surface are coupled to the floor panel, and the connecting portion is coupled to the floor panel, thereby Cross member deformation of the member part and the rear cross member part is constrained to form a cross member having excellent rigidity, and the load from the side frame is efficiently distributed and transmitted to the entire vehicle body via the cross member.

Further, the load transduction pathway formed by the front ridge being formed bent by said front lower surface and the front, and a load transfer path formed by the side edge line after being formed bent by said rear lower surface and a rear surface A load transmission path formed by an array of weld points between the front flange and the floor panel; a load transmission path formed by an array of weld points between the rear flange and the floor panel; least one load path also within the load path formed by the formed reinforcing bead, characterized in that the extending toward the suspension mounting portion.

  According to this structure, the front ridgeline formed by the front lower surface and the front surface, the rear ridgeline formed by the rear lower surface and the rear surface, the weld spot arrangement between the front flange and the floor panel, the rear flange and the floor panel, A load transmission path is formed by the weld point arrangement, reinforcement beads, etc., and the load transmission path is directed to the suspension mounting portion, so that the load input to the suspension mounting portion support portion can be efficiently transmitted to the entire vehicle body via the cross member. The load that is distributed and transmitted and the load acting on the side frame is greatly reduced, and the behavior of the side frame such as torsion and breakage is suppressed, so that it is possible to ensure the improvement of the steering stability of the vehicle.

Further , the connecting portion is coupled to a flange of the side frame on the extension of the weld spot array between the connecting portion and the floor panel.

  According to this structure, the joint rigidity between the side frame and the cross member is improved, and a strong load transmission path is formed by the weld point arrangement, and the load acting on the side frame is efficiently distributed to the entire vehicle body via the cross member. Can communicate.

  According to the present invention, the joint area with the side frame is ensured by having the enlarged portions that expand in the front-rear direction at both ends of the cross member, and the load transmitted from the side frame to the cross member is distributed and transmitted at the connection points. In addition, the load input to the suspension mounting portion is efficiently distributed to the entire vehicle body via the cross member with a simple configuration in which the front edge region and the rear edge region of the enlarged portion extend toward the suspension mounting portion. The impact load that is transmitted and acts on the side frame is greatly reduced, and the behavior of the side frame such as twisting and bending is suppressed.

It is a bottom view which shows the outline of the body frame etc. in a vehicle rear part. It is a principal part bottom view of a vehicle rear part. It is a principal part perspective view of a vehicle rear part lower surface. FIG. 4 is an exploded perspective view of FIG. 3. It is the V section enlarged view of FIG. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is the VII-VII sectional view taken on the line of FIG. It is a perspective view of a center cross member. It is a principal part top view of the conventional vehicle body structure. It is a principal part perspective view of the conventional vehicle body structure.

  One embodiment of a vehicle body rear structure according to the present invention will be described with reference to FIGS.

  1 is a bottom view showing an outline of a vehicle body frame and the like at the rear of the vehicle body, FIG. 2 is a bottom view of the main part of the rear of the vehicle, FIG. 3 is a perspective view of the main part of the lower surface of the rear of the vehicle, and FIG. 5 is an enlarged view of a portion V in FIG. 3, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, FIG. 7 is a sectional view taken along line VII-VII in FIG. In each figure, an arrow Ft indicates the vehicle body front direction.

  As shown in FIGS. 1 to 4, the vehicle body rear part is joined with side frames 10 extending in the front-rear direction, respectively, on the rear parts of the left and right side sills 1 extending along both sides of the lower part of the vehicle body. Each side frame 10 has a pair of vertical walls facing the inner vertical wall 11 and the outer vertical wall 12, and a bottom wall 13. The flanges 11 a and 12 a are bent at the upper ends of the wall 11 and the outer vertical wall 12.

  Each side frame 10 includes a front portion 10A extending in the front-rear direction along the rear portion of the side sill 1, and a kick-up portion that is continuously formed at the rear end of the front portion 10A and is inclined so as to gradually rise from the front side of the rear wheel. The inclined portion 10B and the rear portion 10D extending rearward through a frame bending portion 10C that curves or bends rearward at the rear end of the inclined portion 10B are continuous. The rear end of the side frame 10 is coupled to the rear skirt 15.

  An attachment portion 13b that attaches and supports a front end of a suspension subframe, which will be described later, to the bottom wall 13 at an intermediate position in the front-rear direction of the inclined portion 10B is set as a suspension fastening point Pf. A suspension load in the vertical direction or the vehicle width direction is input to the suspension fastening point Pf from the suspension subframe according to the traveling state.

  A front end cross member 16 extending in the vehicle width direction is bridged between the front ends of the left and right side frames 10, and a front cross member 17 extending in the vehicle width direction is bridged at the front end of the inclined portion 10B. A suspension cross member 18 having a U-shaped cross section and extending in the vehicle width direction is bridged between the vicinity of the front end. A reinforcing frame 19 extending in the front-rear direction is bridged between the center portion of the suspension cross member 18 in the vehicle width direction and the rear skirt 15.

  An attachment portion 18a that attaches and supports the rear end of the suspension subframe to the joint portion between the suspension cross member 18 and the bottom wall 13 of the side frame 10 is set as a suspension fastening point Pr. A suspension load from the suspension subframe is input to the suspension fastening point Pr.

  Between the front cross member 16 and the suspension cross member 18, a center cross member 20, which will be described later, is bridged between the inclined portions 10 </ b> B extending in the vehicle width direction.

  The floor panel 5 is placed on the front end cross member 16, the front cross member 17, the suspension cross member 18, the reinforcing frame 19, and the central cross member 20 and is spanned between the left and right side frames 10. Both sides of the floor panel 5 are coupled to the flanges 11 a of the left and right side frames 10, and the rear ends are coupled to the rear skirt 15.

  Further, the opening of each side frame 10 is closed by a closing plate 6 extending in the longitudinal direction of the vehicle body. A side structure in which a wheel house 7 is formed along the outside of the side frame 10 and the closing plate 6 is provided.

  The upper end of a damper, which will be described later, is attached and supported by a mount bracket 8 that is connected to the side frame 10 and the closing plate 6 between the outside of the frame bending portion 10C of the side frame 10 and the wheel house 7. The position of the mounting portion 8a becomes a damper fastening point Pc, and a relatively large suspension load in the vertical direction from the damper is input.

  For example, when an impact load in the vertical direction is input by the damper to the damper fastening point Pc when the vehicle is running, the side frame 10 displaced in the vehicle width direction from the damper fastening point Pc is twisted via the mount bracket 8 or the like. And the load of an up-down direction is provided. At this time, the deformation of the frame bending portion 10 </ b> C that is bent or curved may be the starting point of the bending deformation of the side frame 10, that is, the start of the bending deformation of the side frame 10. Similarly, when an excessive load is applied to the side frame 10 due to a vehicle rear-end collision or the like, there is a concern that the frame bending portion 10 </ b> C may become a starting point of the side frame 10 for bending deformation.

  Next, the central cross member 20 spanning the left and right side frames 10 will be described with reference to FIGS.

  The central cross member 20 includes a front lower surface 22 that is a front edge region continuous in the vehicle width direction between the left and right side frames 10, and a front surface 23 and a front rear surface that extend along the front and rear edges of the front lower surface 22. A front cross member portion 21 having a U-shaped cross-section with an open upper portion extending in the vehicle width direction, and a rear edge region continuous in the vehicle width direction behind the front cross member portion 21. A rear cross extending in the vehicle width direction in a U-shaped cross-section with a side lower surface 26 and a rear front surface 27 and a rear surface 28 extending along the front and rear edges of the rear lower surface 26 and having an open top. The front cross member portion 21 and the rear cross member portion 25 are connected to each other by a connecting portion 29 having an upper edge of the front rear surface 24 and an upper edge of the rear front surface 27 continuous in the vehicle width direction. Car width direction with a substantially W-shaped cross section Continuing to have the cross member portion. A front flange 23a and a rear flange 28a are bent along the upper edges of the front surface 23 and the rear surface 28, respectively.

  The cross member portion is formed with an enlarged portion 30 in which the front surface 23 and the rear surface 28 are curved to the front side and the rear side, respectively, and are enlarged in the front-rear direction at both ends to be joined to the side frame 10. In particular, the outer end of the front surface 23 that curves forward is smoothly curved along the inner vertical wall 11 of the side frame 10 and reaches the vicinity of the front end of the inclined portion 10 </ b> B that becomes the vicinity of the coupling portion with the front cross member 17.

  The front side lower member 22 of the enlarged portion 30 is a front side edge region that curves so as to be forward as it moves to the end, and the front side cross member portion 21 is directed toward the suspension fastening point Pf. On the other hand, the rear side lower member 26, which is a rear edge region that gently curves so as to be rearward as it moves to the end, is directed toward the frame bent portion 10C and the damper fastening point Pc. Further, a substantially triangular recess is formed between the front lower surface 22 and the rear lower surface 26 by the front rear surface 24, the rear front surface 27, and a connecting portion 29 that connects them.

  Outer ends of the front surface 23, the front rear surface 24, the rear front surface 27, and the rear surface 28 in the enlarged portion 30 can contact the inner vertical wall 11 of the side frame 10, and flanges 23 b that contact the inner wall surface 11 at each end. 24b, 27b, and 28b are bent.

  A stiffening portion 31 that is continuously formed at the ends of the front lower surface 22 and the rear lower surface 26 in the enlarged portion 30 and covers the bottom wall 13 from below from the vicinity of the front end of the inclined portion 10B in the side frame 10 to the frame bending portion 10C is integrated. The flanges 31 a and 31 b that are formed and that can come into contact with the inner vertical wall 11 and the outer vertical wall 12 of the side frame 10 are bent on both sides of the stiffening portion 31.

  A suspension member, a trailing rod attachment portion 32a serving as a suspension attachment portion for attaching and supporting the front end of the trailing rod in this embodiment is formed at the front end of the stiffening portion 31, and the center of the inclined portion 10B of the side frame 10 in the front-rear direction A mounting portion 32b serving as a suspension mounting portion for mounting and supporting the front end of the suspension subframe is formed together with the mounting portion 13b at front and rear positions corresponding to the mounting portion 13b formed in the portion. The attachment portions 13b and 32b serve as suspension fastening points Pf.

  Further, the end portion of the front lower surface 22 extending in the vehicle width direction of the front cross member portion 21 rises in a bead shape and extends to be continuous with the attachment portion 32 b of the stiffening portion 31. Further, the end portion of the rear side lower surface 26 bulges in a bead shape and curves and extends along the stiffening portion 31 and continues to the attachment portion 32b.

  Further, a front ridge line FL having excellent bending rigidity is formed by bending a front portion of the front lower surface 22 extending in the vehicle width direction of the front cross member portion 21 and the front surface 23, and the front ridge line FL is an enlarged portion. At 30, it gently curves forward and extends toward the suspension anchor point Pf. In other words, the suspension fastening point Pf is set on the extension of the front ridge line FL that extends in the vehicle width direction and has excellent bending rigidity.

  On the other hand, a rear ridge line RL which is bent at a continuous portion between the rear end of the rear lower surface 26 and the rear surface 28 and is continuous in the vehicle width direction is formed, and the rear ridge line RL is gently curved backward at the enlarged portion 30. Then, it extends toward the damper fastening point Pc and the frame bending portion 10 </ b> C of the side frame 10. In other words, the damper fastening point Pc and the frame bending portion 10C are set on the extension of the rear ridge line RL excellent in bending rigidity extending in the vehicle width direction.

  As shown in FIG. 4, the central cross member 20 configured as described above includes a cross member portion of the front cross member portion 21 and the rear cross member portion 25 facing the floor panel 5 from the lower side of the vehicle body, and left and right stiffening portions. 31 oppose the inclined portions 10B of the left and right side frames 10, respectively. From this state, as shown in FIG. 3, the left and right stiffening portions 31 are fitted to the inclined portion 10B of the side frame 10 and overlapped with the bottom wall 13, and the front flange 23a and the rear cross member portion of the front cross member portion 21 are overlapped. 25, the rear flange 28a and the continuous portion 29 are brought into contact with the lower surface of the floor panel 5 and set on the lower surface of the vehicle body.

  The set center cross member 20 has a bottom of substantially the entire range of the inclined portion 10B extending from the front end of the inclined portion 10B to which the left and right stiffening portions 31 are secured by the coupling of the front cross member 17 to the frame bent portion 10C. While covering the wall 13, the attachment portion 32 b of the stiffening portion 31 overlaps the attachment portion 13 b of the side frame 10, and is folded to the outer ends of the front surface 23, the front rear surface 24, the rear front surface 27, and the rear surface 28 in the enlarged portion 30. The bent flanges 23 b, 24 b, 27 b, 28 b and the flange 31 a formed inside the stiffening portion 31 abut against the inner vertical wall 11 of the side frame 10. Further, the outer flange 31b of the stiffening member 31 is in contact with the outer vertical wall 12, and the movement of the central cross member 20 in the vehicle width direction is restricted. Further, the connecting portion 29 of the central cross member 20 is substantially linear in the vehicle width direction and abuts against the lower surface of the floor panel 5, and the end 29 a of the connecting portion 29 is located inside the side frame 10 as shown in FIG. It overlaps with the closing plate 6 on the flange 11a bent on the wall 11.

  Further, the rear lower surface 26 extending in the vehicle width direction of the rear cross member portion 25 is extended toward the damper fastening point Pc and the frame bending portion 10C of the side frame 10 so that the damper is on the extension of the rear lower surface 26. The fastening point Pc and the frame bending portion 10C are located. Further, a rear ridge line RL that is bent at a continuous portion between the rear end of the rear lower surface 26 and the rear surface 28 and gently curves rearward extends toward the damper fastening point Pc and the frame bent portion 10C of the side frame 10. It will be in a state that exists.

  As shown in FIG. 5, the set central cross member 20 is formed from the vicinity of the front end of the inclined portion 10 </ b> B where rigidity is secured on both sides of the stiffening portion 31 by the coupling of the front cross member 17. It is spot welded to the bottom wall 13 extending over the frame bending portion 10C, and the inclined portion 10B is stiffened over substantially the entire length by the stiffening portion 31.

  Further, the front flange 23a formed by bending along the front surface 23 is spot-welded to the floor panel 5 at a plurality of points along the vehicle width direction. In particular, the enlarged portion 30 is spot welded to the floor panel 5 at a relatively small welding pitch or a pitch interval that gradually becomes a small pitch, along with the front flange 23a. In the plan view state, it extends toward the suspension fastening point Pf. In other words, the suspension fastening point Pf is set on the extension of the spot welding point array.

  On the other hand, the rear flange 28a bent along the rear surface 28 is spot-welded to the floor panel 5 at a plurality of points along the vehicle width direction. In particular, in the enlarged portion 30, the weld point array is gradually welded back along the rear flange 28a and spot welded to the floor panel 5 at a relatively small welding pitch or a pitch interval that gradually becomes a small pitch. Is set to face the frame bending portion 10C and the damper fastening point Pc of the side frame 10 in a plan view state. In other words, the frame bending portion 10C and the damper fastening point Pc are set on the extension of the weld point row.

  A connecting portion 29 extending in the vehicle width direction is spot-welded to the floor panel 5 at a plurality of points in a straight line along the vehicle width direction. In particular, in the enlarged portion 30, the continuous portion 29 is spot welded to the floor panel 5 at a relatively small pitch, and the end portion 29a of the connecting portion 29 is bent to the inner vertical wall 11 of the side frame 10 as shown in FIG. It is spot welded together with the closing plate 6 to the flange 11a.

  With this configuration, the stiffening portion 31 stiffens a wide range from the front end of the inclined portion 10B to which the front cross member 17 of the side frame 10 is coupled and the rigidity is ensured to the frame bending portion 10C. On the other hand, at the joint portions with the side frame 10 at both ends of the central cross member 20, an enlarged portion 30 that expands in the vehicle front-rear direction is provided, so that a joint area with the side frame 10 is secured and added to the side frame 10. When the load is transmitted to the central cross member 20, no stress is concentrated locally on the enlarged portion 30, and the load is smoothly transmitted to the central cross member 20 from the front end of the inclined portion 10B to the frame bending portion 10C. The installation range of the trailing rod attachment portion 32a, the suspension fastening point Pf, the attachment portion of the mount bracket 8 and the like is efficiently reinforced.

  Further, the side frame 10 is spot welded to the connecting portion 29 of the central cross member 20 and the floor panel 5 with a linear weld point arrangement in the vehicle width direction, and spot welded to the flange 11a of the side frame 10 at the end 29a. A load transmission path a for efficiently distributing and transmitting a load acting on the inclined portion 10B and the frame bending portion 10C to the central cross member 20 and the floor panel 5 along the connecting portion 29 is formed. The deformation of the cross-sectional shapes of the front cross member portion 21 and the rear cross member portion 25 is restrained.

  A suspension fastening point Pf is set on an extended line of the front ridge line FL that is bent and formed by the front lower surface 22 and the front surface 23 in the enlarged portion 30, and a load acting on the suspension fastening point Pf by the front ridge line FL is set. A load transmission path b that transmits to the central cross member 20 is formed.

  In the enlarged portion 30, the front flange 23a and the floor panel 5 are spot-welded at a plurality of points along the vehicle width direction, and a suspension fastening point Pf is set on an extension line of the weld point array. A load transmission path c for distributing and transmitting the applied load to the central cross member 20 and the floor panel 5 is formed at the fastening point Pf.

  Further, the frame bent portion 10C and the damper fastening point Pc are set on the extended line of the rear ridge line RL formed by the rear lower surface 26 and the rear surface 28 in the enlarged portion 30, and the damper fastening point is set by the rear ridge line RL. A load transmission path d is formed in which the load that is input to Pc and acts on the side frame 10 and the load that acts on the frame bending portion 10 </ b> C is distributed and transmitted to the central cross member 20. Further, a load transmission path d for transmitting a load acting on the frame bending portion 10C to the central cross member 20 is formed.

  Similarly, the rear flange 28a and the floor panel 5 are spot-welded at a plurality of points along the vehicle width direction, and the frame bent portion 10C and the damper fastening point Pc are set on the extension line of the weld point array. A load transmission path e for distributing and transmitting the load inputted to the damper fastening point Pc and the load acting on the frame bending portion 10C to the central cross member 20 and the floor panel 5 is formed by the weld point arrangement.

  Here, an outline of a suspension provided with a suspension sub-frame spanned between the left and right side frames 10 will be described.

  This suspension has a rectangular frame-shaped or cross-beam-shaped suspension subframe comprising a pair of left and right side frames extending in the front-rear direction, and a front frame and a rear frame spanned between the left and right side frames. A housing is provided for rotatably supporting the rear wheel.

  In this suspension subframe, the front end of each side frame is attached to the inclined portion 10B of the side frame 10 and the attachment portions 13b, 32b of the stiffening portion 31 of the central cross member 20 via a mounting member such as an elastic bush. The rear end is disposed on the lower surface of the vehicle body by being attached to the attachment portion 18a of the joint portion between the side frame 10 and the suspension cross member 18 via a mounting member such as an elastic bush.

  A trailing arm whose front end is swingably supported by a trailing rod mounting portion 32a set at the front end of the stiffening portion 31 and whose rear end is connected to the housing, and an inner end swingable to the subframe. A lower link and an upper link which are supported and whose outer ends are connected to the housing, and a damper whose lower end is swingably coupled to the housing and whose upper end is mounted and supported on the mounting portion 8a of the mount bracket 8. Consists of a coil spring that absorbs shock by expansion and contraction and a shock absorber such as an oil damper that suppresses the action of the coil spring. In addition, description is abbreviate | omitted about the detailed structure of a damper.

  Due to this suspension, the vertical impact load repeatedly transmitted from the rear wheels due to vehicle running or the like is received from the housing via the damper at the mount bracket 8, that is, at the damper fastening point Pc, and the side frame 10 to which the mount bracket 8 is coupled. Is transmitted to.

  In addition, an impact load in the vehicle width direction and the vertical direction is transmitted from the housing to the suspension subframe through the lower link and the upper link, and the inclined portions of the left and right side frames 10 to which the suspension subframe is attached and supported from the suspension subframe. 10B is distributed and transmitted to the attachment portion 13b, the attachment portion 32b of the stiffening portion 31, and the attachment portion 18a of the rear portion 10D, that is, the suspension fastening points Pf and Pr.

  Further, the longitudinal impact load from the housing is transmitted to the trailing rod mounting portion 32a near the lower end of the inclined portion 10B via the trailing rod.

  On the other hand, when an impact load greater than a predetermined value is input to the rear end of the side frame 10 due to a rear collision or the like, the rear portion of the side frame 10 is crushed and deformed, so-called shaft breakage and absorbs the impact load. 10C is bent upwards and the like is induced.

  Next, the operation of the vehicle body rear part structure configured as described above will be described with reference to FIGS.

  According to this structure, the trailing rod mounting portion 32a and the suspension of the inclined portion 10B extending from the front end of the inclined portion 10B to the frame bent portion 10C, the rigidity of which is ensured by the coupling of the front cross members 17 spanned between the left and right side frames 10. By having enlarged portions 30 that are stiffened over the entire range including the fastening point Pf and that expand in the front-rear direction at both ends of the central cross member 20 at the joint portion with the side frame 10, the frame is bent from the front end of the inclined portion 10B. The installation range of the trailing rod attachment portion 32a reaching the portion 10C, the suspension fastening point Pf, the attachment portion of the mount bracket 8 and the like can be efficiently stiffened.

  Furthermore, by smoothly distributing and transmitting the input load input to the side frame 10 from the suspension accompanying the traveling of the vehicle from the side frame 10 to the central cross member 20, the behavior of the side frame 10 such as torsion and breakage is effectively achieved. Can be suppressed.

  For example, when a relatively large impact load is input from the damper 41 to the mount bracket 8 as the vehicle travels, that is, when a vertical load is input to the damper fastening point Pc, the side frame 10 is connected via the mount bracket 8 or the like. Torsion and a load in the vertical direction are applied to the inclined portion 10B, the frame bending portion 10C, and the like.

  Here, the load formed by the rear ridge line RL in which the extension direction of the enlarged portion 30 of the central cross member 20 coupled to the inclined portion 10B of the side frame 10 is set toward the damper fastening point Pc and the frame bent portion 10C. The damper fastening point Pc and the flange bending are formed by the transmission path d and the load transmission path e formed by a spot welding arrangement in which the extension direction is spot welded to the rear flange 28a and the floor 5 toward the damper fastening point Pc and the frame bending portion 10C. The impact load input to the portion 10C is distributed and transmitted to the central cross member 20, and the vehicle body is transmitted from the central cross member 20 to the floor 5, the other side frame 10, the front cross member 17, the suspension cross member 18, and the like. Is widely distributed. Thereby, the load transmitted from the damper fastening point Pc to the inclined portion 10B and the frame bending portion 10C of the side frame 10 via the mount bracket 8 and the like is greatly reduced, and the behavior of twisting and bending of the side frame 10 is reduced. .

  In addition, the load acting on the frame bending portion 10C is distributed and transmitted to the entire vehicle body via the central cross member 20, and the load acting on the frame bending portion 10C is reduced, so that the behavior of the frame bending portion 10C such as twisting and bending is reduced. It is suppressed.

  Further, as the vehicle travels, a torsional or vertical load is applied to the attachment portion 13b of the inclined portion 10B and the attachment portion 32b of the stiffening portion 31 to which the front end of the suspension subframe is coupled from the suspension subframe. Is done.

  Here, the load transmission by the front ridge line FL extending in the vehicle width direction in the enlarged portion 30 of the central cross member 20 coupled to the inclined portion 10B of the side frame 10 and extending in the direction toward the suspension fastening point Pf. The impact load input to the suspension fastening point Pf is centered by the path b and the load transmission path c formed by spot welding arrangement in which the front flange 23a and the floor panel 5 are spot-welded so that the extension direction is toward the suspension fastening point Pf. It is distributed and transmitted to the cross member 20, and is distributed and transmitted from the central cross member 20 to a wide range of the vehicle body. As a result, the load transmitted from the suspension fastening point Pf to the inclined portion 10B of the side frame 10 is significantly reduced, and the behavior of the side frame 10 in torsion and bending is reduced.

  Further, the load input to the tray long rod mounting portion 32a near the lower end of the inclined portion 10B via the trailing rod is coupled to the wide range of the inclined portion 10B and the lower end of the inclined portion 10B via the stiffening portion 31. Distributedly transmitted to the front cross member 17 and the like, it can be firmly received.

  In addition, the load input to the attachment portion 18a to which the rear end of the suspension subframe is coupled from the suspension subframe, that is, the suspension fastening point Pr is applied to the rear portion 10D of the side frame 10 in which the attachment portion 18a has secured rigidity and the suspension cross. It is set at the connecting portion of the member 18 and can be distributed and transmitted to the side frame 10 and the suspension cross member 18 to be firmly received.

  As described above, when various loads are applied from the suspension to the suspension support portions such as the damper fastening point Pc, the suspension fastening points Pf and Pr, and the trailing rod mounting portion 32a as the vehicle travels, these suspension supports are supported. By efficiently distributing and transmitting the load input to the part to the entire vehicle body via the central cross member 20 or the like, the impact load acting on the side frame 10 is greatly reduced, and the side frame 10 is twisted or broken. The behavior is suppressed, and it is possible to ensure the improvement of the steering stability of the vehicle.

  On the other hand, when an impact load is input to the rear end of the side frame 10 due to a rear impact or the like, the rear lower surface 25, the rear ridge line LR and the rear flange 28a are connected to the inclined portion 10 of the side frame 10 and the floor. The behavior of the side frame 10 is also suppressed by the central cross member 20 whose welded point array 5 is directed to the frame bending portion 10C, so that the side frame 10 is stably deformed, that is, shock absorption by so-called shaft breakage is performed.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention.

  For example, in the above embodiment, the rear lower surface 26 of the rear cross member 25, the rear ridge line RL, and the weld point arrangement of the rear flange 28a and the floor 5 are all the frame bent portion 10C of the side frame 10 and the suspension fastening point Pr. However, only one or two of the rear lower surface 26, the rear ridge line RL, and the welding point array may be directed to the suspension fastening point Pr or the frame bending portion 10C. Similarly, it is also possible to set so that only one of the front edge line FL and the weld point array between the front flange 23a and the floor panel 5 faces the suspension fastening point Pf. In addition, a stiffening beam extending toward the suspension attachment portion may be provided in the enlarged portion, and a load transmission path for transmitting a load acting on the suspension attachment portion to the central cross member can be formed.

5 Floor panel 8 Mount bracket 8a Mounting part 10 Side frame 10C Frame bending part 11 Inner vertical wall 11a Flange 12 Outer vertical wall
13 Bottom wall 13b Mounting portion 20 Center cross member (cross member)
21 Front cross member (front edge area)
23a Front flange 23b Flange 25 Rear cross member (rear edge region)
27b Flange 28a Rear flange 29 Connecting part 30 Enlarged part 31 Stiffening part
32a Trailing rod attachment portion 32b Attachment portion FL Front ridge line RL Rear ridge line Pc Damper fastening point Pf, Pr Suspension fastening point

Claims (6)

In the vehicle body rear structure in which both ends of the cross member extending in the vehicle width direction are connected to a pair of left and right side frames extending in the front-rear direction along both sides of the vehicle body rear part,
Formed at both ends of the cross member is an enlarged portion that expands in the front-rear direction as it moves toward the side frame, and the front edge region and the rear edge region of the enlarged portion extend toward different suspension attachment portions. And
In the front edge region, a front ridge formed by a front lower surface and a front surface constitutes a load transmission path from one of the different suspension attachment portions,
In the rear edge region, a rear ridge line formed by bending a rear lower surface and a rear surface constitutes a load transmission path from the other of the different suspension mounting portions . In the vehicle body rear structure in which both ends of the cross member extending in the vehicle width direction are connected to a pair of left and right side frames extending in the front-rear direction along both sides of the vehicle body rear part,
Formed at both ends of the cross member is an enlarged portion that expands in the front-rear direction as it moves toward the side frame, and the front edge region and the rear edge region of the enlarged portion extend toward different suspension attachment portions. And
The front edge region constitutes a load transmission path from one of the different suspension mounting portions in which the weld point arrangement between the front flange and the floor panel is different,
The vehicle body rear structure, wherein the rear edge region constitutes a load transmission path from the other of the suspension attachment portions where the welding point arrangement between the rear flange and the floor panel differs . Wherein at least one of the front edge region and trailing edge region of the enlarged portion, the rear vehicle body structure according to claim 1 or 2, characterized in that extending toward the frame bend to the curvature of the side frames. The front edge region is a front cross member portion continuous in the vehicle width direction in a U shape with a front lower surface and front side front and front rear surfaces formed bent along the leading and trailing edges of the lower surface Yes,
The rear edge region is a U-shaped cross section having a rear lower surface and a rear front surface and a rear surface bent along the front and rear edges of the rear lower surface and extending in the vehicle width direction. Side cross member,
Said front cross member portion and the rear-side cross member portion is branched in the longitudinal direction in accordance with a rear-side front and the front-rear moves to end with joined via a connecting portion extending in the vehicle width direction, wherein The front flange bent at the front surface and the rear flange bent at the rear surface are coupled to the floor panel, and the connecting portion is coupled to the floor panel . The vehicle body rear structure according to one item . A load transduction pathway formed by the front ridge being formed bent by said front lower surface and the front,
A load transmission path constituted by a rear ridge line formed by bending the rear lower surface and the rear surface;
A load transmission path formed by an array of weld points between the front flange and the floor panel;
A load transmission path formed by an array of weld points between the rear flange and the floor panel;
Claims, characterized in that least one load path also of the load transmission path formed by the reinforcing bead formed toward the suspension fitting portion into the enlarged portion is extended toward the suspension mounting portion 4. The vehicle body rear structure according to 4 . The vehicle body rear part structure according to claim 4 or 5 , wherein the connecting part is coupled to a flange of the side frame on the extension of the weld spot array between the connecting part and the floor panel.

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