JP4722895B2 - Auto body structure - Google Patents

Description

  The present invention relates to a vehicle body structure including a torsion beam type rear suspension.

  As a rear wheel suspension device for a front-wheel drive vehicle, a torsion beam suspension is known in which left and right trailing arms are rigidly coupled with a torsion beam. The torsion beam type suspension has a feature that it has a relatively simple and compact configuration, and provides a smooth ride and a stable turning. In a vehicle equipped with a torsion beam type suspension, the front ends of the left and right trailing arms are normally swingably supported on the floor frame.

  On the other hand, many monocoque structures that facilitate weight reduction while securing rigidity are employed in automobiles. A floor frame of this type of monocoque automobile is generally configured by combining press-formed products made of relatively thin steel plates. Therefore, when excessive stress is locally applied, the portion is easily deformed. Therefore, generally, the supporting portion of the trailing arm is not integrally formed with the floor frame, and the support bracket and the sub frame are spot welded or bolted to the monocoque frame.

As such a structure, for example, the joint part of the trailing arm is arranged between the two vertical walls constituting the floor frame, and one end of the pivot bolt that pivotally supports the joint part is arranged on the inner side in the vehicle width direction of the floor frame. By supporting the collar bolt fixed to the base and supporting the pivot bolt on the support bracket installed on the middle floor cross member, the support rigidity of the suspension arm can be increased and the load input from the suspension can be distributed to the middle cross member. A suspension arm support structure has been proposed by the present applicant (see Patent Document 1).
JP 2006-168607 A

  In the body structure described in Patent Document 1, the collar nut is fixed at a position away from the wall material of the middle floor cross member, and the support bracket transmits the load to the vertical wall and the horizontal wall of the middle cross member. However, when the vehicle turns, a large load acts in the suspension mounting axis direction, that is, the vehicle width direction, and the support direction of the support bracket and the load direction are orthogonal to each other. In order to reliably distribute the load to the middle floor cross member, it is necessary to use a heavy support bracket having a large plate thickness and a large cross-sectional area to increase the bonding strength with the middle floor cross member. For this reason, it is inevitable that the weight of the vehicle body increases. An increase in the weight of the vehicle body is expected to be suppressed as much as possible because it causes a deterioration in driving fuel consumption and a decrease in exercise performance. Further, in this body structure, since the support bracket cannot be used unless the suspension mounting shaft is within the closed cross section of the middle floor cross member, there has been a great design limitation.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a vehicle body structure capable of transmitting a load input from a suspension to a floor frame without causing stress concentration while reducing weight. And

In order to solve the above-described problems, the present invention provides a torsion beam rear in which the front ends of the left and right trailing arms are pivotally supported by a bracket provided below a side sill extension that extends backward from the rear end of the side sill. A vehicle body structure comprising a suspension and a middle floor cross member, which is provided above the rear portion of the rear front floor panel and has a rectangular closed cross section composed of front and rear vertical walls and upper and lower horizontal walls , joined to the side sill extension. a is, in the vehicle width direction inner side of the bracket, the trailing arm inner holder for supporting one end of the support shaft of the trailing arms are joined, the lower transverse wall of the middle floor cross member, is its side The middle is inclined downward toward the side sill extension, and the middle The front vertical wall of the lower cross member extends downward from the joint portion with the lower horizontal wall of the middle floor cross member, and the rear center portion of the rear front floor panel is joined to the lower end of the lower cross member. Is formed in an upward slope toward the side sill extension at the side, and a notch is formed on both sides of the rear part of the rear front floor panel, and a three-dimensional projecting structure having a recessed holding part. A gusset plate formed to have a shape is joined to the lower end side portion of the front vertical wall of the middle floor cross member, the rear side portion of the rear front floor panel, and the side sill extension so as to cover the notch, and the holding under the middle floor cross member while holding the lower half of the trailing arm inner holder in parts Configured to connecting the sill extension and lateral wall.

In the vehicle body structure for an automobile provided with the structure mentioned above, it is a good test to place the holder in the joint portion with different height between the rear front floor panel.

  According to the present invention, a large load in the direction of the suspension mounting axis when turning the vehicle flows to the vertical wall of the middle floor cross member without concentration of stress. As a result, the weight of the automobile can be reduced. In addition, the front floor panel is joined to the front vertical wall extending downward from the closed cross section, so that the suspension mounting rigidity is improved without arranging the suspension mounting shaft in the closed cross section of the middle floor cross member. This increases design flexibility.

  In addition, by joining the gusset plate to the lower side wall of the cross member, a large load in the direction of the suspension mounting axis when turning the vehicle can be distributed to the closed cross section of the middle floor cross member. The efficiency is further improved, and the weight of the automobile can be further reduced. Further, by arranging the support portion of the gusset plate at a height different from the joint portion with the front floor panel, the shape of the rear portion of the front floor panel is simplified, and the formability of the front floor panel is improved. In addition, the floor frame is a side sill extension that extends backward from the rear end of the side sill, and the left and right ends of the middle floor cross member are joined to the inner side in the vehicle width direction so that the trailing arm is attached to the side sill. Even if it is inclined, the middle floor cross member supports the load input from the suspension in the closed cross section in the vehicle width direction, so that the suspension mounting rigidity is improved.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a vehicle body structure in which the present invention is applied to a body for a hatchback passenger car will be described in detail with reference to the drawings.
<< Configuration of Embodiment >>
FIG. 1 is a perspective view of a vehicle body skeleton structure according to an embodiment, partially broken away. As shown in FIG. 1, the body 1 of the embodiment is a floor frame in which a pair of left and right side sills 2 and 3 extending in the longitudinal direction of the vehicle body and an intermediate portion between both side sills 2 and 3 are coupled in the vehicle width direction. 1 middle floor cross member 4, second middle floor cross member 5 connecting the rear ends of both side sills 2, 3 in the vehicle width direction, a pair of left and right rear frames 6 extending rearward from the rear ends of both side sills 2, 3 As a floor panel, a dashboard lower panel 8 that defines the front end of the passenger compartment and the rear end of the engine compartment, front and rear front floor panels 9a and 9b that constitute the floor of the passenger compartment, and spare tires A rear floor panel 11 that forms a pan 10 and forms a floor surface of a luggage compartment is provided.

  FIG. 2 is a perspective view of the rear skeleton structure of the automobile according to the embodiment as seen from the bottom side. As shown in FIG. 2, the left and right rear wheels Wl and Wr are suspended from the body 1 by a torsion beam type rear suspension 12. The torsion beam type rear suspension 12 includes a pair of left and right trailing arms 13 and 14 and a torsion beam 15 whose both ends are rigidly coupled to an intermediate portion between the trailing arms 13 and 14 as main components. Both trailing arms 13 and 14 have their front ends 13a and 14a pivotally supported by side sill extensions 2a and 3a extending upwardly from the rear ends of the side sills 2 and 3 so as to swing freely, and rear ends 13b. , 14b pivotally support the left and right rear wheels Wl, Wr. Spring seats 13c and 14c are respectively joined to the rear portions of the coupling portions of the trailing arms 13 and 14 with the torsion beam 15, and the load of the body 1 is transmitted to the torsion beam type rear suspension 12 via a spring (not shown).

  Next, a vehicle body structure that pivotally supports the trailing arms 13 and 14 will be described with reference to FIGS. 3 is a perspective view of the rear portion of the front floor panel as viewed from the front side in FIG. 1, and FIG. 4 is a partial cutaway view of the cross member stiffener. FIG. 5 is a plan view of the main part of the vehicle body skeleton structure, with the cross member stiffener partially cut away, FIG. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. It is VII-VII sectional drawing in the inside. 3 to 7 show each part on the left side of the vehicle body structure. Since the body structure of an automobile is generally symmetric, the left side of the body structure shown in the drawings will be described in describing the components provided on the left and right.

  As shown in FIGS. 3 to 5, the second middle floor cross member 5 is connected to the inside of the side sill extension 2a in the vehicle width direction, and its lower end is joined to the rear end of the rear front floor panel 9b by spot welding. Has been. The second middle floor cross member 5 is composed of a cross member 21 and a cross member stiffener 22 each having an L-shaped cross section, and these are joined together to form a rectangular closed cross section. The cross member 21 forms a rear vertical wall 21a and a lower horizontal wall 21b in a rectangular cross section, and the cross member stiffener 22 similarly forms a front vertical wall 22a and an upper horizontal wall 22b. Notches are formed on both sides of the rear portion of the rear front floor panel 9b, and the gusset plate 30 is joined to the second middle floor cross member 5, the side sill extension 2a, and the rear front floor panel 9b so as to cover the notches. Has been.

  As shown in FIG. 6, at the junction between the second middle floor cross member 5 and the side sill extension 2a, a trailing arm is provided on the outer side and the inner side of the side sill extension 2a via a pivot bolt 31 (support shaft). The outer bracket 32 and the inner bracket 33 that pivotally support the front end 13a of the 13 are joined together. The side sill extension 2a, the outer bracket 32, and the inner bracket 33 are respectively provided with bolt insertion holes in a straight line, and a nut 34 is fixed to the inner side in the vehicle width direction of the insertion hole of the inner bracket 33 by welding. ing. The pivot bolt 31 is inserted into these insertion holes from the outer side in the vehicle width direction, is fitted into the nut 34, and supports the front end 13a of the trailing arm 13 via the rear suspension bush 16 so as to be able to swing. That is, the nut 34 is disposed in the closed cross section 5 i of the second middle floor cross member 5 and supports the distal end side of the pivot bolt 31.

  The upper side wall 22 b of the second middle floor cross member 5 extends to the side sill extension 2 a and is joined thereto, but the lower side wall 21 b is joined to the inner bracket 33 via the gusset plate 30. The side portion of the lower lateral wall 21b and the gusset plate 30 are inclined downward toward the side sill extension 2a, and the gusset plate 30 is joined to the inner bracket 33 in a manner to hold the lower half of the nut 34. Specifically, as shown in FIG. 4, the gusset plate 30 has a holding portion 30a that is recessed and surrounds the lower half of the nut 34, and the nut 34 fitted to the holding portion 30a has both sides in the front-rear direction. Are fixed to the gusset plate 30 by a filler material a.

  The gusset plate 30 is joined to the inner bracket 33 by spot welding in the closed cross section of the second middle floor cross member 5, joined to the rear vertical wall 21a by spot welding at the welding point b, and the welding points c, It is joined to the lower lateral wall 21b by spot welding at d. Outside the closed section, the gusset plate 30 is joined to the front vertical wall 22a by spot welding at welding points e to l, and joined to the rear front floor panel 9b and the inner bracket 33. In the gusset plate 30, inclined portions 30b and 30c are respectively formed at the joint portions between the front vertical wall 22a and the rear front floor panel 9b, and the holding portion 30a is disposed at a position higher than the rear front floor panel 9b.

  The front vertical wall 22a seen through in FIG. 4 is joined to a flange 21c formed at the front end of the lower horizontal wall 21b by spot welding at the welding points e, m to p. And the front side vertical wall 22a is further extended below rather than the said junction part, and the lower end is joined with the rear part front floor panel 9b. The height of the portion extending below the front vertical wall 22a is reduced in the vicinity of the vehicle width direction side end due to the downward inclination of the lower side wall 21b and the upward inclination of the gusset plate 30, and at the vehicle width direction side end. The lower end of the front vertical wall 22 a is directly joined to the gusset plate 30, and the side end of the front vertical wall 22 a is joined to the inner bracket 33.

<< Effects of Embodiment >>
Next, the effect in the body 1 of this embodiment is demonstrated. In general, the pivot bolt 31 that pivotally supports the rear suspension receives a vertical load from the trailing arms 13 and 14 when the vehicle is stopped and when the vehicle is traveling straight, and the vehicle is longitudinally moved during acceleration and braking. The load of works. On the other hand, when the vehicle turns, a load acts in the axial direction of the pivot bolt 31, that is, in the vehicle width direction. The brackets 32 and 33 are provided vertically along the longitudinal direction of the vehicle body. In particular, a load orthogonal to the bracket support direction acts on the inner bracket 33 on the outer ring side having a high cornering force. Therefore, it is necessary to reliably distribute the load acting on the inner bracket 33 to the middle floor cross member, and the load must be transmitted from the support bracket to the middle floor cross member without causing stress concentration.

  In the present embodiment, the holding portion 30a of the gusset plate 30 is held so as to surround the lower half of the nut 34 joined to the inner side of the inner bracket 33 in the vehicle width direction, and inside the vehicle width direction on the axis of the nut 34, Since the gusset plate 30 is spot-welded to the front vertical wall 22a at the welding points e, f, and g, the load in the direction of the suspension mounting axis when turning the vehicle is not concentrated on the second middle floor cross member 5 without stress concentration. It flows to the front vertical wall 22a. Therefore, by using a relatively light steel sheet as the material of the gusset plate 30, the structural efficiency of the suspension mounting portion can be increased and the weight of the automobile can be reduced.

  In addition, since the holding portion 30a of the gusset plate 30 is also joined to the rear vertical wall 21a at the welding point b, the load in the vehicle width direction also flows to the rear vertical wall 21a to avoid stress concentration. Has been. Further, the nut 34 is disposed in the closed section 5i of the second middle floor cross member 5, and the holding portion 30a of the gusset plate 30 is spot welded to the lower lateral wall 21b at the welding points c and d. The load in the width direction is reliably distributed to the second middle floor cross member 5. Therefore, the efficiency of the reinforcing structure of the suspension mounting portion is further improved, and further weight reduction of the automobile is achieved.

  Further, the front vertical wall 22a extends further downward from the joint (welding points m to p) with the lower lateral wall 21b, and the front end of the rear front floor panel 9b is joined to the lower end thereof. The second middle floor cross member 5 may not be disposed within the closed cross section 5i. This increases the degree of freedom in designing the suspension mounting structure. On the other hand, in this embodiment, the load transmission efficiency is further improved by arranging the nut 34 in the closed cross section 5i. Thus, when the nut 34 is provided at a higher position than the rear front floor panel 9b, conventionally, the rear front floor panel 9b needs to be press-molded into a three-dimensional shape with the rear end portion protruding. This made it difficult to form the rear front floor panel 9b. However, as in the above embodiment, by using a relatively large gusset plate 30 as a holding member for the nut 34, the three-dimensional shape is realized in the gusset plate 30, and the shape of the rear front floor panel 9b is simplified. As a result, the moldability could be improved.

  The trailing arm 13 is pivotally supported by a side sill extension 2a extending rearward from the rear end of the side sill 2, and the end surface of the second middle floor cross member 5 is joined to the inner side in the vehicle width direction. Therefore, even if the trailing arm 13 is inclined with respect to the side sill 2, the load in the vehicle width direction input from the torsion beam type rear suspension 12 is supported by the closed cross section, and the suspension mounting rigidity is improved.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, although the above-described embodiment is an application of the present invention to a hatchback passenger car, it may be applied to other forms of cars such as a 2/4 door sedan car or SUV. In the above embodiment, the trailing arm is pivotally supported by the bracket provided on the side sill extension. However, the trailing arm can be directly pivotally supported by the side sill extension with increased rigidity, or the other floor frame can be pivoted. It is also possible to support them. Furthermore, specific shapes and joining forms such as a gusset plate and a floor middle cross member, and specific forms such as a trailing arm inner holder and a holding portion for holding the same are appropriately changed without departing from the gist of the present invention. Is possible.

The perspective view which shows the vehicle body frame structure which concerns on embodiment partially fractured | ruptured The perspective view which shows the bottom face of the rear part vehicle body frame structure which concerns on embodiment View along arrow III in Fig. 1 Fig. 3 arrow view in Fig. 2 showing the cross member stiffener partially broken A plan view of the main part of the vehicle body skeleton structure showing the cross member stiffener partially broken. VI-VI cross section in FIG. VII-VII sectional view in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body 2,3 Side sill 2a, 3a Side sill extension 4 1st middle floor cross member 5 2nd middle floor cross member 9 Front floor panel 9b Rear front floor panel 11 Rear floor panel 12 Torsion beam type rear suspension 13, 14 Trailing arm 21 Cross Member 21a Rear vertical wall 21b Lower horizontal wall 22 Cross member stiffener 22a Front vertical wall 22b Upper horizontal wall 30 Gusset plate 30a Holding part 31 Pivot bolt (support shaft)
32 Outer bracket 33 Inner bracket 34 Nut (trailing arm inner holder)
a Filler material b to p Welding point Wr, Wl Rear wheel

Claims (2)

A torsion beam type rear suspension with the front ends of the left and right trailing arms pivotally supported by a bracket provided under the side sill extension that extends backward from the rear end of the side sill, and above the rear rear floor panel. provided, a vehicle body structure that the middle floor cross member having a closed cross section of the rectangular consisting of front and rear vertical walls and below the transverse wall Prefecture, formed by joining the side sill extensions,
In the vehicle width direction inner side of the bracket, the trailing arm inner holder for supporting one end of the support shaft of the trailing arms are joined,
The lower side wall of the middle floor cross member has a downward slope toward the side sill extension.
The front vertical wall of the middle floor cross member extends downward from the joint portion with the lower horizontal wall of the middle floor cross member, and the rear center portion of the rear front floor panel is joined to the lower end thereof. The lower end of the side portion is inclined upward toward the side sill extension,
Notches are formed on both sides of the rear front floor panel,
A gusset plate that has a holding portion that is recessed and is shaped so as to exhibit a projected three-dimensional shape, a lower end side portion of a front vertical wall of the middle floor cross member so as to cover the notch, and the rear front floor The lower side wall of the middle floor cross member is connected to the side sill extension while being joined to the rear side of the panel and the side sill extension, and holding the lower half of the trailing arm inner holder with the holding part. Characteristic car body structure. The vehicle body structure according to claim 1, wherein the holding portion is disposed at a height different from a joint portion with the rear front floor panel.

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