JP3820850B2 - Chassis frame reinforcement structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reinforcing structure for a chassis frame that strengthens its rigidity in the front-rear direction of a vehicle body, and in particular, is formed into a substantially ladder shape by combining a pair of left and right side rails having a substantially U-shaped cross section and a plurality of cross members. The present invention relates to a reinforcing structure for a chassis frame.
[0002]
[Prior art]
Vehicles such as trucks and microbuses have a chassis frame formed in a substantially ladder shape at the base of the vehicle body, strengthening the rigidity of the same part, attaching the axle side via suspension to the lower part, and cab on the upper part side Mounting and supporting cabins, cargo boxes, etc. By the way, the front end portion of the chassis frame is easily subjected to an impact load when the vehicle collides. Therefore, from the viewpoint of absorbing the impact load in the vicinity of the front end of the chassis frame, it is desirable to adopt a cross-sectional structure in which the portion is likely to be buckled. On the other hand, from the viewpoint of securing a living space with a chassis frame disposed directly under a cab or the like, the rigidity of the part is enhanced, and for example, a closed cross-sectional structure is adopted only on the front end side.
[0003]
Japanese Utility Model Laid-Open No. 2-44572 discloses an example of rigidity enhancement of a chassis frame having a substantially U-shaped cross section.
[0004]
[Problems to be solved by the invention]
By the way, in the chassis frame 100 shown in FIG. 7, when a side rail 110 having a substantially U-shaped cross section receives an impact load F from the tip during a collision, a partial buckling deformation occurs at a portion n having the lowest rigidity on the front end side. Then, bending deformation is repeatedly generated in the vicinity thereof, and the front end side is bent greatly and moved to the rear side m without absorbing impact energy due to sufficient buckling deformation.
For this reason, it is desirable to secure a sufficient amount of deformation resistance on the front end side of the side rail 110, and not only the absorption of impact energy due to buckling deformation, but also the amount of impact energy absorbed during bending deformation is sufficiently ensured. It is hoped that.
[0005]
An object of the present invention is to provide a chassis frame reinforcing structure capable of sufficiently absorbing impact energy based on the above-described problems.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 is a reinforcing structure for a chassis frame having a substantially U-shaped cross section, comprising a web portion extending in the front-rear direction of the vehicle body and a flange portion extending from the upper and lower ends thereof. A closed cross-sectional area in which a section that is a predetermined length behind the vehicle front end side is formed in a closed cross-sectional shape, an open cross-sectional area that is continuously formed behind the closed cross-sectional area, and an upper flange portion in the open cross-sectional area A lower part closed cross section is formed by connecting a projecting piece projecting downward and having a downward edge rising upward toward the rear of the vehicle and a lower flange portion and a web portion of the open cross section area. An upward base portion formed with an upward surface opposite to the downward edge, and when an external force in the front-rear direction is applied to the vehicle body, the projecting piece rides on the upward surface of the upward base portion and impact energy characterized in that it absorbs
Therefore, when an external force in the front-rear direction applied to the vehicle body is applied to the open cross-sectional area via the closed cross-sectional area, the open cross-sectional area generates bending deformation resistance, and at the same time, the projecting piece rides on the upward surface. The bending rigidity in the open cross-sectional area is strengthened, and at this time, the deformation between the upper and lower flanges is expanded, whereby the bending deformation resistance can be further increased, and the shock absorption amount is sufficiently increased. For this reason, the closed cross-sectional area can absorb the shock at the time of collision.
Desirably, the closed cross-section component member in the closed cross-sectional area and the projecting piece in the open cross-sectional area may be formed as one part, and in this case, the structure and assembly can be simplified.
[0007]
According to a second aspect of the present invention, in the chassis frame reinforcing structure according to the first aspect, the upper flange portion of the open cross-sectional area is formed so as to form an inclined wall toward the rear from the closed cross-sectional area. And
In this case, since the upper flange portion of the upward inclined wall is formed following the closed cross-sectional area, the bending stress is surely concentrated on this part, and the deformation for absorbing the shock can be performed more reliably in the open cross-sectional area. , Deformation for shock absorption is stabilized.
[0008]
According to a third aspect of the present invention, in the chassis frame reinforcing structure according to the first or second aspect, the downward edge is offset from the vehicle width direction inner edge portion of the upward base in the vehicle width direction outer side. It is characterized by that.
In this case, since the protruding piece is positioned outside the inner edge in the vehicle width direction of the upward base portion, when an impact load is applied to the open cross-sectional area, the protruding piece can surely run on the upward base portion, The bending deformation resistance in the open cross-sectional area can be reliably increased.
Preferably, the upward base may be attached with a bulkhead that closes the lower partial closed section. In this case, since the rigidity of the upward base is enhanced, an impact load is applied to the open cross-sectional area, and the bending deformation resistance in the open cross-sectional area is sufficiently increased when the protruding piece rides on the upward base. Can do.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a chassis frame 1 to which a chassis frame reinforcing structure according to an embodiment of the present invention is applied. The chassis frame 1 constitutes a vehicle body base portion of the truck T shown in FIG. 3, and includes a pair of left and right side rails 2 having a substantially U-shaped cross section extending in the front-rear direction X and a plurality of cross members 3 extending in the vehicle width direction Y (see FIG. 3 (a) is formed in a substantially ladder shape by combining a plurality of 3a to 3c). Here, the pair of left and right side rails 2 are arranged with the opening of the substantially U-shaped cross section facing the inner side in the vehicle width direction Y, and the both side rails 2 have a symmetrical shape. The side rail 2 will be mainly described.
[0010]
As shown in FIG. 3A, the side rail 2 is mounted with a bumper 10 via a bracket 101, the cab 4 is placed on the front side portion that follows the bumper 10, and the cargo box D is placed behind the cab 4. As shown in FIG. 1, the side rail 2 has a front end area E0, a closed cross-sectional area E1 having a relatively small vertical width h1 on the front end side, an inclined area E2 that follows, and a large open cross section that has a relatively long vertical width h2 that follows. And E3. The floor (not shown) of the cab 4 is formed with the front portion facing the closed cross-sectional area E1, the middle portion facing the inclined area E2, and the rear portion facing the front side portion of the open cross-sectional area E3. And is coupled to the side rail 2.
[0011]
As shown in FIG. 2, the side rail 2 basically has a substantially U-shape with a web portion 5 forming a vertical plate and upper and lower flange portions 6 and 7 extending inward in the vehicle width direction Y from the upper and lower ends thereof. A cross-sectional shape is formed. Further, upper and lower flanges 301 and 301 at the left and right ends of the cross member 3 are overlapped between the upper and lower flange portions 6 and 7 of the left and right side rails 2 and are welded to each other. Only the lower flange portion 7 of the side rail 2 is continuously formed without change over the entire region in the front-rear direction X.
The closed cross-sectional area E1 on the front end side of the side rail 2 is welded with a web portion 501 having a relatively small vertical width h1, upper and lower flanges 601 and 7, and upper and lower flange portions g1 and g2 superimposed on the inner surfaces of both flanges. And a first stiffener 8 as a closed cross-section constituent member that forms a closed cross-section.
An inclined area E2 following the closed cross-sectional area E1 is continuously formed on the rear end side of the web section 501 in the same area, and the rear of the upper flange section 601 and the web section 502 formed so that the longitudinal width h1 is increased later. And an upper flange portion 602 that is formed continuously on the end side and forms an inclined wall that is inclined upward toward the rear of the vehicle. Moreover, the front end of the first stiffener 8 is continuously formed, and a protruding piece 9 extending to the rear side of the upper flange portion 602 is provided, and the upper end portion thereof is welded to the upper flange portion 602. The protruding piece 9 is formed with a downward edge c with an upward inclination toward the rear of the vehicle.
[0012]
Second stiffeners 11 as the upward base portion over a front end of the subsequent inclined zone E2 open sectional area E3 are joined. The second stiffener 11 is a bracket having a key-shaped cross section and a predetermined length L1. The upper end edge of the second stiffener 11 is welded to the web portion 502 and the lower end edge is welded to the lower flange portion 7. The main portion of the inclined region E2 has an open cross section. A lower partial closed section B is formed in the lower part. Moreover, the second stiffener 11 is formed with an upward surface f at the top thereof, and the front end side of the upward surface f is disposed close to a position facing the downward edge c. As shown in FIG. 4, a bulkhead 12 that closes the lower partial closed section B is welded to a position near the front end of the second stiffener 11. The bulkhead 12 can enhance the rigidity of the front portion of the second stiffener 11, and when the protruding piece 9 rides on the upward surface f, it can enhance the bending rigidity of the inclined area E2 and the open cross-sectional area E3, and bend and deform. The resistance can be increased sufficiently.
[0013]
As shown in FIGS. 1A and 1B, the downward edge c of the projecting piece 9 is outside the vehicle width direction Y with respect to the inner edge 111 of the second stiffener 11 in the vehicle width direction Y (FIG. 1 ( In b), the upper side is shifted by an offset amount α. As a result, when an impact load is applied to the inclined area E2 and the open cross-sectional area E3, bending deformation occurs in the inclined area E2 and the open cross-sectional area E3. Even if it is relatively deviated in the vehicle width direction Y from the initial expectation with respect to the 11 side, the projecting piece 9 side can be reliably brought into contact with the upward surface f of the second stiffener 11, and the inclined region E2 And the bending deformation resistance of the open cross-sectional area E3 can be increased reliably.
In relation to this, the inner edge 111 of the second stiffener 11 protrudes inward in the vehicle width direction Y and deviates from the lower flange 7, so here, the lower edge of the second stiffener 11 is bent and the lower flange 7, and the bent end j (see FIG. 4) is welded to the lower flange portion 7.
[0014]
In the open cross-sectional area E3 following the inclined area E2, a web portion 503 having a vertical width h2 and the upper and lower flanges 603 and 7 thereof are continuously formed rearward as they are, at the rear end of the inclined area E2. The rear end side of the second stiffener 11 is formed to extend by a predetermined amount in the open cross-sectional area E3. Again, the opposing edge portions of the second stiffener 11 are welded to the web portion 503 and the lower flange portion 7 to form the lower partial closed cross section B at the lower front end of the open cross section area E3, thereby enhancing the bending rigidity of the open cross section area E3. The bending deformation resistance can be increased. In addition, as shown to Fig.6 (a), a wire harness and various pipes can be easily accommodated in the open space a of the upper half part of the open cross-sectional area E3, and both securing of an accommodation area and reinforcement of rigidity can be aimed at.
[0015]
It is assumed that a truck T equipped with such a chassis frame 1 collides and an impact load F is applied to the pair of left and right side rails 2 via the front bumper 10 and the cross member 3. By this impact load F, first, the tip end region E0 is buckled and deformed, and the closed cross-sectional area E1 of both side rails 2 whose rigidity has been reinforced by the first stiffener 8 is suppressed from being deformed, and the inclined area E2 and the open cross-sectional area E3 are reduced. , Buckling deformation accompanying displacement in the direction of reference D2 occurs, indicating deformation resistance. In this case, the bending stress accompanying the bending displacement of the closed cross-sectional area E1 can be surely concentrated on the upper flange portion 602 of the upward inclined wall, and the deformation for absorbing the shock can be surely performed. Deformation for shock absorption is stabilized.
[0016]
Furthermore, when the projecting piece 9 is displaced D1 (see FIGS. 4 and 5) toward the upward surface f of the second stiffener 11, the bending deformation proceeds while the projecting piece 9 is in contact with the front portion of the upward surface f. Then, as shown by a two-dot chain line in FIG. 6B, the projecting piece 9 receives a reaction force P from the upward surface f, and the upper flange 602 on the projecting piece 9 side and the lower flange 7 on the second stiffener 11 side are relative to each other. Therefore, the gap h is deformed in the direction of enlarging, and a large deformation resistance is generated at this portion, so that excessive bending displacement can be reliably suppressed.
By sequentially generating each of such deformation resistances, the impact energy can be reliably and sequentially absorbed, and the impact can be mitigated. Moreover, since the upward displacement R of the closed cross-sectional area E1 can be kept small, deformation of the front part of the cab 4 located at the upper part of the closed cross-sectional area E1 can be suppressed to the minimum, and passenger safety can be protected.
[0017]
In the above description, the first stiffener 8 as the closed cross-section constituent member in the closed cross-sectional area E1 is integrally formed with the projecting piece 9 in the front-rear direction to form one part. For this reason, the number of parts can be reduced, the welding points to the side rail 2 can be relatively reduced, the number of assembling steps can be reduced, and the cost can be reduced. In some cases, the first stiffener 8 and the projecting piece 9 may be formed as separate parts.
In the above description, the vehicle has been described as the truck T. However, the present invention can be similarly applied to a passenger car having a chassis frame, a trailer, a bus, and the like, and similar operational effects can be obtained.
[0018]
【The invention's effect】
As described above, according to the first aspect of the present invention, when an external force in the front-rear direction is applied to the vehicle body, the projecting piece rides on the upward surface and reinforces the bending rigidity in the open cross-sectional area. By deforming in the direction, the bending deformation resistance can be further increased and the amount of shock absorption can be increased sufficiently, so that the closed cross-sectional area can undergo shock absorption deformation at the time of collision.
[0019]
Since the invention according to claim 2 forms the upper flange portion of the upward inclined wall following the closed cross-sectional area, the bending stress is surely concentrated on this portion, and the deformation for absorbing the shock is more reliably performed in the open cross-sectional area. And deformation for shock absorption is stabilized.
[0020]
In the invention according to claim 3, since the downward edge is formed offset to the vehicle width direction outer side with respect to the vehicle width direction inner edge portion of the upward base, the projecting piece is placed outside the vehicle width direction inner edge of the upward base portion. Therefore, when an impact load is applied to the open cross-sectional area, the projecting piece can surely run on the upwardly-facing table, and the bending deformation resistance in the open cross-sectional area can be reliably increased.
[Brief description of the drawings]
1A and 1B show a chassis frame of a truck to which a chassis frame reinforcement structure according to an embodiment of the present invention is applied; FIG. 1A is a side sectional view of a main part of a side rail in the chassis frame, and FIG. FIG.
FIG. 2 is a cutaway perspective view of a main part of the chassis frame of FIG. 1;
3 is a partially cutaway view of the track of FIG. 1, wherein (a) is a schematic plan view and (b) is a schematic side view.
4 is a cutaway perspective view of a main part of a side rail in the chassis frame of FIG. 1. FIG.
5 is a cross-sectional side view of a main part after a collision deformation of a side rail in the chassis frame of FIG. 1. FIG.
6 shows a cross-section of the side rail in FIG. 1, where (a) is a cross-sectional view in an open cross-sectional area, and (b) is a cross-sectional view in an inclined area E2.
FIG. 7 is a schematic partial view illustrating a modification of a conventional side rail.
[Explanation of symbols]
1 Chassis frame 2 Side rail (chassis frame)
5 Web part 6 Upper flange part 7 Lower flange part 9 Projection piece 11 Second stiffener (upward base part)
c Downward edge f Upward surface B Lower partial closed section E1 Closed section area E3 Open section area T Track (vehicle body)
X longitudinal direction

Claims (3)

In the reinforcing structure of the chassis frame having a substantially U-shaped cross section comprising a web portion extending in the front-rear direction of the vehicle body and a flange portion extending from the upper and lower ends thereof,
A closed cross-sectional area in which a section that is a predetermined length behind the vehicle front end side is formed in a closed cross-sectional shape, an open cross-sectional area that is continuously formed behind the closed cross-sectional area, and downward from the upper flange portion of the open cross-sectional area And a projecting piece formed with a downward edge protruding upward toward the rear of the vehicle and a lower flange portion and a web portion of the open cross-sectional area to be connected to form a lower partial closed cross section and the downward direction An upward base portion formed with an upward surface facing the edge, and when the external force in the front-rear direction is applied to the vehicle body, the protruding piece rides on the upward surface of the upward base portion to absorb impact energy. A chassis frame reinforcement structure characterized by The chassis frame reinforcing structure according to claim 1,
A reinforcing structure for a chassis frame, wherein the upper flange portion of the open cross-sectional area is formed so as to form an inclined wall that extends rearward from the closed cross-sectional area. In the reinforcing structure of the chassis frame according to claim 1 or 2 ,
A reinforcing structure for a chassis frame, wherein the downward edge is formed to be offset outward in the vehicle width direction with respect to the vehicle width direction inner edge of the upward base.

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