JP2015098251A - Vehicle body rear structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body rear structure capable of improving rigidity and also improving steering stability.SOLUTION: A vehicle body rear structure includes: a floor panel 10; a pair of side frames 20 extending along the floor panel 10 in a front-to-rear direction and arranged distanced from each other in a vehicle width direction; a sub-frame 30 to which suspension arms supporting rear wheel hubs are swingably attached, and which is bridged between the right and left side frames 20 so as to be fastened from below; and a stiffening member 100 fastened to fastened portion 110 of the sub-frame 30 in which the sub-frame 30 is fastened to the side frames 20, respectively, coupling the right and left fastened portions 110 to each other, and fixed to the floor panel 10 in a plurality of portions in an intermediate part between the right and left fastened portions 110. The stiffening member 100 includes lower rigidity parts 150 and 160 set to be lower in rigidity than the other parts between the fixed portions 120.

Description

  The present invention relates to a vehicle body rear structure of an automobile, and particularly relates to an improved vehicle body having improved rigidity and steering stability.

2. Description of the Related Art A vehicle body such as a passenger car generally has a structure in which a side frame having a closed cross section and extending in the front-rear direction is coupled to a lower floor of a cabin formed of steel or an aluminum alloy and having a monocoque structure.
In recent years, in order to improve various performances such as steering stability, noise, vibration, and ride comfort, a structure such as a subframe that is a separate part from the vehicle body is fastened to the lower side of the side frame. A structure in which a suspension arm is provided with a fulcrum on the vehicle body side is widely used.

As a conventional technique related to a vehicle body structure of a passenger car having a subframe, for example, Patent Document 1 describes the purpose of reducing the weight of the vehicle body and improving the layout flexibility of the routing member while improving the support rigidity and the vehicle body rigidity of the front suspension. In addition, it is described that a high-rigidity part and a low-rigidity part that is thinly formed with respect to the high-rigidity part are appropriately disposed in each part of the front subframe.
Further, in Patent Document 2, connecting members for connecting the rear subframe and the vehicle body are provided on the left and right sides of the rear subframe, respectively, to increase the support rigidity of the rear subframe and improve the steering stability. Have been described.

JP 2013-159223 A JP 2002-347650 A

As described in Patent Document 2, by providing a stiffening member and connecting the subframe and the vehicle body, the support rigidity of the rear suspension and the vehicle body rigidity are improved, and the response of steering and the straight running stability are improved. can do.
Such an effect can be further improved by connecting the left and right stiffening members so as to connect the left and right fastening portions of the subframe and the vehicle body to each other and fasten to the vehicle body floor at the intermediate portion. I know that there is.

However, when such stiffening is applied, the rigidity of the rear part of the vehicle body is locally improved, so that the ground contact property of the rear wheel tire is deteriorated and the discontinuity of the vehicle body behavior with respect to the steering operation is deteriorated. May occur.
Therefore, it is required to optimize the rigidity setting of such a stiffening member. However, for example, the conventional technique described in Patent Document 1 has reduced the weight as a low-rigidity part simply having a margin in strength and rigidity. However, there is no description or suggestion of the problem of positively improving the steering stability by setting the rigidity.
In view of the above-described problems, an object of the present invention is to provide a vehicle body rear structure that has improved rigidity and improved steering stability.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a floor panel that constitutes a vehicle body floor, a pair of side frames that extend back and forth along the floor panel and are spaced apart in the vehicle width direction, and a rear wheel hub. A suspension arm to be supported is swingably attached, and is fastened at a fastening position between a subframe that is fastened from the lower side between the left and right side frames and the side frame of the subframe. And a stiffening member fixed to the floor panel at a plurality of locations in the middle portion between the left and right fastening locations, the stiffening member comprising a plurality of fastening locations with the floor panel. It is a vehicle body rear structure characterized by having a low-rigidity part whose rigidity is set lower than that of other parts at intervals.
According to this, the rigidity of the vehicle body can be improved to improve the response to the steering operation and the straight running stability, the vehicle body strength can be increased, and the durability can be improved.
Furthermore, by forming the low rigidity portion, it is possible to prevent the vehicle body rigidity from being excessively improved, improve the ground contact property of the rear wheel tire and the continuity of the vehicle body behavior, and improve the steering stability.

The invention according to claim 2 is characterized in that a side structure constituting a vehicle body side surface portion is provided outside the side frame in the vehicle width direction, and both end portions of the stiffening member are connected to the side structure. The vehicle body rear structure according to Item 1.
According to this, the above-mentioned effect can be promoted by further increasing the rigidity of the vehicle body.

According to a third aspect of the present invention, the stiffening member has a cross-sectional shape in which flanges are formed at front and rear end portions of the surface portion disposed substantially horizontally in a region other than the low-rigidity portion, and the low-rigidity member is provided. 3. The part according to claim 1, wherein a flange is formed only in one of the front and rear end portions, and a long hole extending in the vehicle width direction is formed in the central portion of the surface portion. This is a rear structure of the vehicle body.
According to this, the bending rigidity is secured to some extent while the torsional rigidity of the stiffening member is lowered by leaving the front and rear flanges and the surface portions on both sides of the elongated hole. Further, it is possible to prevent the stiffening member from being deformed at the time of attachment to the vehicle body and to ensure productivity.

  As described above, according to the present invention, it is possible to provide a vehicle body rear structure that has improved rigidity and improved steering stability.

It is the top view which looked at the Example of the vehicle body rear part structure to which this invention is applied from the vehicle lower side. It is the external appearance perspective view which looked at the vehicle body rear part structure of FIG. 1 from the vehicle lower side. FIG. 2 is a two-side view of a support subframe in the vehicle body rear structure of FIG. 1. FIG. 4 is a cross-sectional view taken along arrows aa and bb in FIG. 3.

  The present invention aims to provide a vehicle body rear structure with improved rigidity and improved steering stability, by fastening a support subframe from the lower side of the subframe, connecting the left and right fastening points with the sideframe of the subframe. The problem was solved by fastening the two parts to the floor panel and forming a low-rigidity part in the middle of the left and right fastening points to the floor panel.

Embodiments of a vehicle body rear structure to which the present invention is applied will be described below.
The vehicle body rear structure according to the embodiment is applied to an automobile such as a passenger car, for example.
FIG. 1 is a plan view of the rear body structure of the embodiment as viewed from the lower side of the vehicle.
FIG. 2 is an external perspective view of the vehicle body rear structure according to the embodiment as viewed from the lower side of the vehicle (diagonally rear side and oblique left side).

  The vehicle body rear structure 1 includes a floor panel 10, a side frame 20, a sub frame 30, a rear suspension 40, a side structure 50, a support sub frame 100, and the like.

The floor panel 10 is a part that constitutes a floor surface portion of a vehicle body having a steel plate monocoque structure, for example.
The floor panel 10 is configured by press-molding a steel plate, for example.
A spare tire pan 11 is formed at the center in the vehicle width direction in the vicinity of the rear end of the floor panel 10.
The spare tire pan 11 is a portion formed by projecting the floor surface of the cargo compartment portion downward in a blister shape to accommodate a spare tire (not shown).

The side frame 20 is a structural member that extends in the front-rear direction along the lower surface of the floor panel 10.
The side frame 20 is configured as a closed cross section having a rectangular cross section viewed from the vehicle front-rear direction, for example, and the upper surface portion thereof is joined to the floor pan 10.
A pair of side frames 20 are provided substantially symmetrically spaced apart in the vehicle width direction.
The spare tire pan 11 is disposed between the left and right side frames 20 behind the subframe 30.

The left and right side frames 20 are connected by a rear seat cross member 21 provided at the lower part of the rear seat provided in the vehicle interior.
The rear seat cross member 21 is a structural member that extends in the vehicle width direction along the lower surface of the floor panel 10.
A fuel tank (not shown) is accommodated in a region on the rear side of the rear seat cross member 21 and on the front side of the sub frame 30.

The sub frame 30 is a structural member attached to the side frame 20 from below, and is provided with a vehicle body side fulcrum of each arm (link) of the rear suspension 40.
The sub-frame 30 is formed in a cross beam shape by joining the front member 31, the rear member 32, and the side member 33 by welding or the like.

The front member 31 and the rear member 32 are members extending along the vehicle width direction between the left and right side frames 20.
The front member 31 and the rear member 32 are spaced apart from each other in the front-rear direction of the vehicle.
Both ends of the front member 31 and the rear member 32 are fastened to the left and right side frames 20 via vibration-proof rubber.
The anti-vibration rubber is configured, for example, as a cylindrical rubber bush having a central axis substantially along the vertical direction.
The anti-vibration rubber is fastened to a welding nut provided in the side frame 20 by a bolt inserted from below into the center portion of the inner cylinder.
The outer cylinder of the anti-vibration rubber is press-fitted into a cylindrical portion provided at both ends of the front member 31 and the rear member 32 and fixed.
The side member 33 is a member that is provided at the side end of the front member 31 and the side end of the rear member 32 and extends in the front-rear direction.
Further, the sub-frame 30 is provided with a rear differential (not shown) that transmits a driving force transmitted from a transmission provided at the front portion of the vehicle to the left and right rear wheels.

The rear suspension 40 supports a housing 41 to which a rear wheel is attached so as to be swingable along a predetermined locus with respect to the vehicle body.
The housing 41 is, for example, a cast iron member that houses a hub bearing that rotatably supports a hub to which the rear wheel is fixed.

The rear suspension 40 includes a lower arm 42, an upper arm 43, a toe control arm 44, a trailing arm 45, a damper unit 46, a stabilizer 47, and the like.
The lower arm 42 is a link that is swingably connected to the lower end portion of the housing 41 and the rear end portion of the side member 33 of the subframe 30 and extends substantially along the vehicle width direction.

The upper arm 43 is a link that is swingably connected to an upper end portion of the housing 41 and an upper portion of the side member 33 of the subframe 30 and extends substantially along the vehicle width direction.
The upper arm 43 cooperates with the lower arm 42 to position the rear wheel in the camber direction.

The toe control arm 44 is swingably connected to the lower end portion of the housing 41 and the front end portion of the side member 33 of the subframe 30 on the front side of the lower arm 42, and extends substantially along the vehicle width direction. It is a link.
The toe control arm 44 cooperates with the lower arm 42 to position the rear wheels in the toe direction.

The trailing arm 45 is a link that is swingably connected to a lower portion of the housing 41 and a vehicle body in front of the housing 41 and extends substantially along the vehicle front-rear direction.
The trailing arm 45 is disposed so as to be inclined so that the front end portion is higher than the rear end portion.
The trailing arm 45 is for positioning the rear wheel in the front-rear direction.

The damper unit 46 is a unit (subassembly) of a damper (shock absorber) and a coil spring.
The damper unit 46 is disposed so that the expansion / contraction direction is substantially along the vertical direction, the lower end portion is connected to the middle portion of the lower arm 42, and the upper end portion is connected to a bracket formed on the vehicle body.

  The stabilizer 47 is configured by connecting the left and right lower arms 42 with a stabilizer bar (torsion bar) formed of spring steel, and generates a roll reaction force when the left and right suspensions stroke in the opposite direction to roll the vehicle. Increases rigidity.

The side structure 50 is a structure in which an outer panel, an inner panel, pillars, a wheel arch 51 in which a rear wheel is accommodated, a wheel apron 52, and the like constituting a side surface portion of a vehicle body are sub-assembled.
1 and 2, only the wheel arch 51 and the wheel apron 52 are shown, and the others are not shown.

The support subframe 100 is a stiffening member provided between the left and right fastening portions of the subframe 30 with the side frame 20 at both ends of the rear member 32.
The support subframe 100 is also fastened to the spare tire pan 11 of the floor panel 10 at the intermediate portion between the left and right fastening portions of the rear member 32 and the side frame 20 described above.
Further, both end portions in the vehicle width direction of the support subframe 100 are further extended with respect to both end portions of the rear member 32 and fastened to the lower rear end portion of the wheel apron 52 in the side structure 50.

Hereinafter, the support subframe 100 will be described in more detail.
FIG. 3 is a two-side view of the support subframe.
3A is a plan view seen from the lower surface side when the vehicle is mounted, and FIG. 3B is a diagram seen from the front side of the vehicle (a cross section taken along the line B-B in FIG. 3A). FIG.
FIG. 4 is a cross-sectional view of the main part of the support subframe.
4A is a cross-sectional view taken along the line aa in FIG. 3A, and FIG. 4B is a cross-sectional view taken along the line bb in FIG. 3A.

The support subframe 100 is integrally formed, for example, by press molding a steel plate.
The support subframe 100 includes a subframe fastening portion 110, a floor fastening portion 120, an apron fastening portion 130, a stiffening bead 140, a notch 150, a long hole 160, and the like.

The subframe fastening portion 110 is a portion into which bolts for fastening the support subframe 100 to the side frame 20 via both end portions of the rear member 32 of the subframe 30 are inserted.
The subframe fastening portion 110 is fastened together with the subframe 30 by bolts that fasten the subframe 30 to the vehicle body.
The subframe fastening portion 110 is formed wider than the other portion of the support subframe 100 so as to enlarge in the radial direction of the bolt hole.
A pair of subframe fastening portions 110 are provided corresponding to the left and right side frames 20.
One bolt hole in the vehicle width direction is a long hole having a longitudinal direction along the vehicle width direction in order to absorb dimensional tolerances.

The floor fastening portion 120 is provided at a substantially central portion of the intermediate portion 100A that connects the left and right subframe fastening portions 110.
The intermediate portion 100A is formed substantially straight substantially along the vehicle width direction in the plan view shown in FIG.
Further, the intermediate portion 100A is formed to be curved so that the center portion is lower than the side end portion in the front view shown in FIG.
The floor fastening portion 120 has a bolt hole that fastens the support subframe 110 to the lower surface portion of the floor panel 10 in the vicinity of the front end portion of the spare tire pan 11.
A pair of floor fastening portions 120 are provided substantially symmetrically and spaced apart in the vehicle width direction.

The apron fastening part 130 is provided at the projecting end part of the projecting part 100B formed by projecting horizontally from the left and right end parts of the intermediate part 100A in the vehicle width direction.
The protrusion 100B is formed so as to be inclined with respect to the intermediate portion 100A so that the protrusion is slightly retracted with respect to the subframe fastening portion 110 in plan view.
The apron fastening portion 130 has a bolt hole that fastens the support subframe 100 to the wheel apron 52 of the side structure 50.

The stiffening beads 140 are respectively provided between the left and right subframe fastening portions 110 and the floor fastening portion 120 in the intermediate portion 100A.
The stiffening bead 140 is formed by projecting a surface portion in a blister shape, and extends substantially along the vehicle width direction.

The notch 150 is a portion formed by notching the rear flange 103 among the front flange 102 and the rear flange 103 formed respectively before and after the intermediate portion 100A between the left and right floor fastening portions 120.
The long hole 160 is formed in a region where the notch 150 is provided, and extends along the vehicle width direction.
The notch 150 and the long hole 160 cooperate to constitute a low-rigidity part in which the torsional rigidity of the intermediate part 100A is locally reduced with respect to other parts.

Hereinafter, the cross-sectional shape in the intermediate portion 100A will be described.
4B, the basic cross section of the intermediate portion 100A other than the low-rigidity portion has a front flange 102 that protrudes downward from a front end portion and a lower end portion of the upper surface portion 101 extending substantially along the horizontal direction. A rear flange 103 is provided.
In the notch 150 shown in FIG. 4A, the entire rear flange 103 and a part of the rear edge of the upper surface 101 are removed.
Further, in the region where the notch 150 is provided, a long hole 160 is formed in the center of the top surface 101 along the vehicle width direction.

As described above, according to the present embodiment, the left and right fastening portions of the rear member 32 of the side frame 20 and the subframe 30 are connected by the intermediate portion 100A of the support subframe 100 and the center of the intermediate portion 100A. By fastening the part to the spare tire pan 11, the vehicle body rigidity can be improved, and the responsiveness and straightness to the steering operation can be improved.
This also increases the strength of the vehicle body and improves the durability.
Furthermore, by forming a low-rigidity part having a notch part 150 and a long hole 160 in the middle of the left and right floor fastening parts 120, the vehicle body rigidity is prevented from being excessively improved, and the grounding property of the rear wheel tire is reduced. The continuity of the vehicle behavior can be improved and the steering stability can be improved.
Further, by forming the protrusions 100B at the left and right ends of the support subframe 100 and fastening the protrusions to the wheel apron 52 of the side structure 50, the vehicle body rigidity can be further improved.
In addition, by adopting a configuration in which the low-rigidity portion has the notch portion 150 provided only on the rear side and the long hole 160, for example, the front and rear flanges are removed, or the width of the upper surface portion is narrowed. When the rigidity is reduced by other methods, it becomes easy to secure the bending rigidity while appropriately reducing the torsional rigidity of the support subframe 100, and it is easy to secure the bending rigidity at the time of manufacturing parts, during transportation, and to the vehicle body. It is possible to ensure productivity by preventing the support subframe 100 from being deformed at the time of mounting.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention, and the shape of each member constituting the vehicle body rear structure, The structure, material, manufacturing method, and the like are not limited to the above-described embodiments, and can be changed as appropriate.
For example, the suspension type, the shape of each part of the vehicle body, and the like can be changed as appropriate.
Further, the stiffening member (support subframe) is not limited to the one made of a sheet metal panel as in the embodiment, but may be one using a pipe material, for example. Further, the configuration of the low rigidity portion is not particularly limited.

DESCRIPTION OF SYMBOLS 1 Vehicle body rear structure 10 Floor panel 11 Spare tire pan 20 Side frame 21 Rear seat cross member 30 Sub frame 31 Front member 32 Rear member 33 Side member 40 Rear suspension 41 Housing 42 Lower arm 43 Upper arm 44 Toe control arm 45 Trailing arm 46 Damper unit 47 Stabilizer 50 Side structure 51 Wheel arch 52 Wheel apron 100 Support subframe 100A Intermediate part 100B Projection part 101 Upper surface part 102 Front flange 103 Rear flange 110 Subframe fastening part 120 Floor fastening part 130 Apron fastening part 140 Stiffening bead 150 Notch part 160 long hole

Claims (3)

A floor panel constituting the vehicle body floor,
A pair of side frames that extend back and forth along the floor panel and are spaced apart in the vehicle width direction; and
A suspension arm that supports the rear wheel hub is swingably attached, and a subframe that is fastened from below between the left and right side frames;
A stiffening member that is fastened to a fastening portion of the sub-frame with the side frame, connects the left and right fastening portions, and is fixed to the floor panel at a plurality of positions in an intermediate portion between the left and right fastening portions. ,
The vehicle body rear structure, wherein the stiffening member has a low-rigidity part having a lower rigidity than other parts at intervals of a plurality of fixing points with the floor panel. A side structure constituting a vehicle body side part is provided on the vehicle width direction outer side of the side frame,
The vehicle body rear portion structure according to claim 1, wherein both ends of the stiffening member are connected to the side structure. The stiffening member has a cross-sectional shape in which flanges are formed at front and rear end portions of a surface portion that is disposed substantially horizontally in a region other than the low rigidity portion. The vehicle body rear part structure according to claim 1 or 2, wherein a flange is formed only in one of the flanges, and a long hole extending in the vehicle width direction is formed in a central part of the surface part.

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