JP2004175228A - Vehicle front underrun protector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy vehicle front underrun protector capable of increasing the crushing strength of the protector itself to that of a steel protector and having a high weight reduction effect as compared with the steel protector. <P>SOLUTION: This front underrun protector comprises an aluminum alloy hollow member 2 having a rectangular sectional shape. A thickness of each of lateral walls 4a, 4b constituting this rectangular hollow section is set to be 4 to 8mm. A thickness of each of the lateral walls 4a, 4b is set to be thicker than that of each of the vertical walls 3a, 3b constituting the rectangular hollow section. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle front underrun protector having excellent crush strength against a load at the time of a vehicle collision.
[0002]
[Prior art]
In the event of a frontal collision between a vehicle such as a truck and a passenger car, the lower part of the front bumper is to prevent passenger cars from slipping under the front (front) bumper of the truck and to ensure passenger safety. , A front underrun protector (a device for preventing undercarriage of a vehicle, hereinafter simply referred to as a protector) is disposed.
[0003]
The structure of the protector for trucks is basically made of a hollow material having a rectangular cross section such as a mouth and having a cross section extending in the longitudinal direction (axial direction). And it is arrange | positioned under the truck front bumper so that it may extend substantially horizontally in the vehicle width direction.
[0004]
At the time of a frontal collision between a vehicle such as the truck and a passenger car, a local collision load of 5 to 20 tons is applied to the protector. Therefore, the protector is required to have a crushing strength that can withstand this impact load (lateral load). For this reason, steel protectors made of high-strength steel such as high strength have been mainly used.
[0005]
Incidentally, the collision load applied to the bumper at the time of a vehicle collision with another passenger vehicle is about 10 to 15 tons at the time of a full collision such as a barrier collision. However, if the local collision load of a truck or the like is converted to about 5 to 6 tons, it becomes significantly lighter than the local collision load of the truck protector and the required crushing strength.
[0006]
In order to increase the strength of the protector as a device, various proposals have conventionally been made to reinforce a protector support structure such as a bracket for supporting the protector (attached to a front end portion of a vehicle body frame) (for example, see Patent Document 1). It has also been proposed to provide a cylindrical impact energy absorbing device made of FRP between the bracket and the protector (see Patent Document 2).
[0007]
[Patent Document 1]
JP-A-2002-302000 (pages 1-2, FIG. 1)
[Patent Document 2]
JP-A-2000-296743 (pages 1-2, FIG. 1)
[0008]
In recent years, in order to reduce the body weight of trucks, the use of aluminum alloy extruded hollow sections and the like for these protectors instead of conventionally used steel has begun to be studied.
[0009]
However, the reinforcement of the protector support structure proposed in the past, such as Patent Documents 1 and 2, presupposes the use of a steel protector having a high crushing strength. For this reason, in aluminum alloy protectors that have insufficient crushing strength compared to steel protectors, even if the support structure of these protectors is reinforced, the crushing strength of the protector as long as the protector device has the same rectangular cross-sectional shape. It does not increase.
[0010]
When the aluminum alloy protector is designed to have the same rectangular cross-sectional shape as the steel protector, the crushing strength against the large collision load is insufficient. On the other hand, if the thickness of the aluminum alloy protector (the thickness of the wall constituting the rectangular cross section) is increased in order to increase the crushing strength, the weight of the protector increases, and the weight reduction effect on the steel protector is lost. Is
[0011]
On the other hand, it has been disclosed that, for example, the protector is made of an extruded aluminum material, and a number of through holes (square holes) are formed in an axial direction of the protector so that a cross section orthogonal to the vehicle width direction has a number of holes. (See Patent Document 3). In this Patent Document 3, at the time of a collision load, the hole is crushed to absorb the collision energy by crushing the hole. In comparison, the purpose is to increase the crushing strength.
[0012]
[Patent Document 3]
JP-A-2000-272444 (pages 1-2, FIG. 1)
[0013]
[Problems to be solved by the invention]
However, Patent Literature 3 can certainly reduce the weight compared to the solid material, but the crushing strength is reduced while reducing the weight compared to the rectangular hollow cross-sectional shape such as the mouth shape, which is the object. Can not be enhanced. As a result, it is difficult to commercialize an aluminum alloy protector instead of a steel protector.
[0014]
That is, in order to provide a large number of holes and reduce the weight as much as a rectangular hollow cross-section such as a mouth as in Patent Document 3, it is necessary to provide an excessively large hole or an excessively large number of holes. However, in this case, inevitably the thickness of each of the many walls constituting the hole becomes thin. Here, Patent Document 3 has a large number of walls constituting a hole, and therefore, when assuming an aluminum alloy profile, the lateral crush strength is one sheet larger than that of a rectangular hollow cross-sectional shape such as a mouth. The thickness of the wall per sheet becomes thinner, which is rather disadvantageous. For this reason, the crushing strength cannot be increased more than a rectangular hollow cross-sectional shape such as a mouth shape, and conversely, the crushing strength may be lower than that of a rectangular hollow cross-sectional shape such as a mouth shape.
[0015]
On the other hand, in order to increase the crushing strength, on the other hand, it is inevitable to increase the thickness of a large number of walls constituting the hole. The number of walls for thickening is increased, and the weight is sacrificed at the expense of disadvantage, and the effect of reducing the weight as compared with the solid material is reduced.
[0016]
As described above, since it is difficult to reduce the weight and increase the high-pressure breaking strength of an aluminum alloy protector, it has been difficult to put it to practical use instead of a steel protector.
[0017]
Therefore, an object of the present invention is to provide a vehicle front underrun protector made of an aluminum alloy, which has a crushing strength of the protector itself as high as that of a steel protector and has a higher weight-saving effect than a steel protector. .
[0018]
[Means for Solving the Problems]
In order to achieve this object, the gist of the vehicle front underrun protector according to the present invention is that the cross-sectional shape is made of a hollow aluminum alloy material having a rectangular cross section, and that the thickness of a horizontal wall portion constituting the rectangular hollow cross section is 4 to 8 mm. The thickness of the horizontal wall is made larger than the thickness of the vertical wall constituting the rectangular hollow cross section. Here, the distinction between the horizontal wall portion and the vertical wall portion is made based on a rectangular hollow cross-section arrangement state assuming a use mode of the protector (a case where the protector is arranged to extend substantially in the vehicle width direction). You.
[0019]
In the protector, not only the steel protector but also, generally, the horizontal wall portion and the vertical wall portion forming the rectangular cross section of the hollow member of the protector have substantially the same thickness. On the other hand, in the present invention, first, the thickness of the horizontal wall portion forming the rectangular cross-sectional shape of the hollow member is set to 4 to 8 mm. As described above, in the present invention, the thickness of the horizontal wall portion is slightly increased from the thickness of the normally used wall portion of the steel protector of 3 to 4 mm and the thickness of the vertical wall portion forming the rectangular hollow cross section. The crushing strength of the aluminum alloy protector is, for example, one of the concrete guides, a protector having a generally square cross section made of ordinary steel (wall thickness: 3 to 4 mm, wall length: 60 to 40 mm) currently used. 100mm).
[0020]
On the other hand, the thickness of the vertical wall is made thinner than that of the horizontal wall (the thickness of the horizontal wall is made thicker than the thickness of the vertical wall) to increase the weight saving effect on the steel protector. At this time, the thickness of the vertical wall portion is set to a thickness that can guarantee the crushing strength of the aluminum alloy protector to be equal to that of the steel protector, and is not further reduced.
[0021]
The lateral wall portion of the aluminum alloy protector is parallel to the direction of the collision load (lateral load) of 5 to 20 tons in a truck collision. For this reason, the degree of contribution to the crush strength against this large load is higher than that of the vertical wall. For this reason, in the present invention, the thickness of the side wall portion having a high contribution to the crushing strength is made relatively thick. And, by this, the thickness of the vertical wall portion can be made thinner than that of the horizontal wall portion so as not to lower the crushing strength of the increased aluminum alloy protector below that of the steel protector, thereby reducing the weight of the steel protector. Can be increased.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the aluminum alloy protector of the present invention will be specifically described. FIGS. 1A and 1B are perspective views showing one embodiment of the aluminum alloy protector of the present invention.
[0023]
First, in FIG. 1A, an aluminum alloy protector 1a is made of an aluminum alloy extruded hollow shape member 2 having a substantially square rectangular cross section. Reference numeral 7 denotes a hollow portion of the hollow profile member 2, 4a and 4b denote two horizontal walls (also referred to as horizontal wall portions) forming a substantially square cross section, and 3a and 3b denote two vertical walls (vertical wall portions) forming a substantially square cross section. ). The horizontal walls 4a and 4b and the vertical walls 3a and 3b are arranged substantially parallel to each other, and the horizontal walls and the vertical walls cross each other at a substantially right angle.
[0024]
1 (a) and 1 (b), the protector 1a (hollow shaped member 2) extends in a direction substantially perpendicular to the load direction (lateral direction, arrow F) from the left side in the figure at the time of a vehicle collision. It is used in a substantially horizontal arrangement.
[0025]
In the embodiment shown in FIG. 1A, the protector 1a (hollow shaped member 2) has a linear central portion 6 extending in the axial direction, and both ends 5a, 5b in the axial direction (longitudinal direction) are connected to the vehicle. It curves backward (to the right in the figure).
[0026]
The protector 1b of FIG. 1 (b) has the same structure as the protector 1a except that the protector 1b of FIG. 1 (a) has no curved portions 5a, 5b at both ends and is linear in the axial direction. Shape. The axial or longitudinal shape of such a protector is appropriately selected according to the front body design of the truck.
[0027]
The curved portions 5a and 5b at both ends like the protector 1a in FIG. 1A are obtained by hot extrusion of an aluminum alloy from a linear hollow material 2 as shown in FIG. 1B. By bending both ends of the hollow profile 2, the hollow profile 2 can be obtained integrally and easily with the hollow profile. Therefore, the aluminum alloy protector of the present invention has an advantage that the curved portions at both ends having a desired bending angle and length can be integrally formed according to the front body design of the truck.
[0028]
By the way, steel cannot extrude such a hollow profile, and in order to obtain a steel protector, a steel plate is formed into a hollow shape and then hollowed by welding or mechanical joining, or The two parts formed in a U-shape are butted against each other and made into a hollow material by welding or mechanical joining. As described above, in order to obtain the protector made of hollow steel, it is not possible to integrally form the protector unless the above-mentioned means such as welding is used, and it is difficult to manufacture the curved portions 5a and 5b at both ends.
[0029]
Hereinafter, the cross-sectional shape of the aluminum alloy protector of the present invention will be described.
Here, FIG. 1 (a), the present invention an aluminum alloy protector 1a of (b), in 1b, the vertical wall portion 3a, 3b (3a are front side vertical wall, 3b is rear side vertical wall) each thickness _{t f} of , the length of each length L _f and transverse walls 4a, 4b (4a the upper transverse wall, 4b is lower transverse wall) the thickness of each of the to _{t w,} the respective lengths and _{L w,} protector (hollow profile 2) Is L.
[0030]
In the present invention, not only a high-strength 7000 series aluminum alloy having a 0.2% proof stress of 300 MPa or more but also a 0.2% proof stress, which is generally used for a bumper reinforcing material for a passenger car and has a similar cross-sectional shape to the protector of the present invention, has a 0.2% proof stress. It is also an important object to use a general-purpose 6000 series aluminum alloy such as 6063 having 250 MPa or less for the protector.
[0031]
Of course, in the present invention, a high-strength 7000 series aluminum alloy may be used to increase the high-pressure breaking strength of the protector. The use of a 7000 series aluminum alloy has the advantage that the walls of the protector (hollow member) can be made thinner and lighter. However, since the 7000 series has high strength, productivity such as extrusion processing is inferior as thicker as compared with 6000 series aluminum alloys and the like, and the refining treatment (heat treatment) for increasing the strength is performed. However, there is a problem in the production of the hollow material, such as that the method is complicated. Therefore, if a 6000 series aluminum alloy or the like can be used for the protector, such a problem is solved.
[0032]
However, when using aluminum alloys such as 6000 series having a 0.2% proof stress of 250 MPa or less, the crushing strength of the protector is equal to that of ordinary steel, as compared with the case of using a higher strength 7000 series aluminum alloy. Elevating and increasing the weight saving effect on steel protectors is a particularly difficult task.
[0033]
In contrast, in the present invention, each lateral wall portion 4a constituting the rectangular hollow cross-section of the protector, 4b with the thickness _{t w} 4 _~8mm of the respective lateral wall portions 4a, the thickness _{t w} of 4b, Kakutatekabe parts 3a, is solved by having thicker than 3b of the thickness t _f. As a result, even when using not only a high-strength 7000 series aluminum alloy but also a low-strength 6000 series aluminum alloy having a 0.2% proof stress of 250 MPa or less, the crushing strength of the protector is increased to the same level as that of ordinary steel. This solves the problem of increasing the effect of reducing the weight of the protector.
[0034]
The thickness t _w is 4mm or less in each lateral wall portion is made thinner than the normal wall thickness 3 to 4 mm to be used for steel protector, contribution to crushing strength against the large load at the time of track collision lack of thickness t _w of the high lateral wall portion, not ordinary steel protector average of strength can not be obtained. On the other hand, in the lateral wall portion thickness t _w is more than 8mm of the weight is increased, weight reduction ineffective against steel protector.
[0035]
On the other hand, the vertical wall portions 3a, 3b has a thickness t _f of the crushing strength of the aluminum alloy protector mainly determined by the thickness t _w of the transverse walls, more thick Satoshi that can guarantee to the parallel the steel protector, in order to reduce the weight of , thinner than the thickness t _w of the lateral wall portion. Since the thickness _{t w} of the transverse walls is a 4 ~8mm, the preferred range of the thickness _{t f} of the vertical wall portion is 3 ~6mm. This, say in both of the relationship between _{t f} and _{t w,} it is preferable that the _t f / t _w and from 0.3 to 0.7. or t f _/ t _w is the crushing strength decreases too thin t _f is less than 0.3, t _w is too thick may not out weight reduction effect. On the other hand, beyond t f _/ t _w is 0.7, closer to the thickness of the lateral wall and the vertical wall portion are the same prior art, there may not be enhanced crush strength.
[0036]
The thickness t _{w of} the two horizontal wall portions 4a and 4b and the thickness t _f of the two vertical wall portions 3a and 3b are not necessarily the same between the horizontal wall portions and between the vertical wall portions as in the protector of FIG. No need. For example, in the above-described ranges, the horizontal wall portions 4a are thicker than the upper horizontal wall portion 4b, and the front vertical wall portion 3a is thicker than the rear vertical wall portion 3b. The thickness of each part may be changed. When the hollow profile 2 is obtained by hot extrusion of an aluminum alloy, there is also an advantage that the hollow profiles 2 having different wall thicknesses can be easily and easily obtained.
[0037]
The shape of the rectangular (square) hollow cross section of the protector of the present invention is to increase the crushing strength of the protector to that of ordinary steel even when using a low-strength 6000 series aluminum alloy having a 0.2% proof stress of 250 MPa or less. Is most preferably a square shape. Crushing strength improving effect of the thickness t _w of said lateral wall portion has a length L _w of the lateral wall portions, in the case of the same square shape as the length L _f of the vertical wall portion, is exhibited to the maximum. Thus, for L _w is L _f, be too long, be too short, in other words, vertically long, or indeed a long rectangle side, crushing strength improving effect of the thickness t _w of said lateral wall portion is reduced . However, it is not necessary that the shape be strictly square. If the shape is close to a square, this effect does not change. Extent to which this effect does not change, generally _{L f} / L _w is in the range of 0.8 to 1.2.
[0038]
In this range, the lengths _Lw and _f of the horizontal wall portions and the vertical wall portions do not necessarily have to be the same, and the lengths may be changed in the above range. In this case, the horizontal walls 4a and 4b and the vertical walls 3a and 3b are not parallel to each other and are arranged at a certain angle, and the horizontal walls and the vertical walls are not at right angles to each other but at a certain angle. Intersect. For example, if the length of the front vertical wall portion 3a of the protector of the present invention is made longer than the length of the vertical wall portion 3b on the rear side, a tapered protector angled from the front side to the rear side of the protector is obtained. If the relationship is reversed, a reverse tapered protector is obtained. As a result, the crushing strength can be controlled, and the degree of freedom in design, bonding, or arrangement can be increased. In the case of hot extrusion of an aluminum alloy, there is also an advantage that such a hollow material can be easily and easily obtained.
[0039]
In the present embodiment of the aluminum alloy protector, the example of the rectangular hollow cross section has a mouth shape. From the viewpoint of weight reduction, this mouth-shaped hollow structure is preferable, and the mouth-shaped hollow structure enables high-pressure breaking strength. However, the required crushing strength varies depending on the type of truck and the regulations, and in some cases, the crushing strength is required rather than the weight reduction. Therefore, in such a case, in order to further increase the crushing strength of the aluminum alloy protector, for example, a cross-sectional shape in which a reinforcing middle rib is added in the horizontal or vertical direction in the rectangular hollow portion 7 in FIG. It is also possible to make the cross section into a Japanese shape, a rice shape, an eye shape, or the like.
[0040]
The length L of the aluminum alloy protector 1 shown in FIG. 1 is determined as appropriate according to the width of the truck and the front design, but is generally about 60 to 200 mm.
[0041]
Next, one mode of use of the aluminum alloy protector of the present invention (mode of the underrun protector device) will be described with reference to FIGS. FIGS. 2 and 3 are plan views each showing a main part of the truck where an aluminum alloy protector is attached to the front portion, and FIG. 3 is a front view of FIG.
[0042]
2 and 3, reference numeral 10 denotes a bumper extending in the vehicle width direction at the front of the truck, 11a and 11b denote body frames (side rails and chassis frames) extending in the length direction of the vehicle, and 12 denotes side rails. A first cross member extending in the connecting vehicle width direction, 14 is a front tire, and 15 is a truck body.
[0043]
13a and 13b are, for example, brackets that support the aluminum alloy protector 1a of FIG. 1A from the rear and are connected to the vehicle body frames 11a and 11b. The protector 1a is disposed at an appropriate height below the front bumper 10 according to the vehicle height of the truck in order to prevent the passenger car from slipping under the truck front bumper.
[0044]
The support of the protector 1a by the brackets 13a and 13b and the structure of the bracket are not shown in detail, but a known manner of mounting an underrun protector device can be appropriately adopted. For example, a flange is provided at the tip of the plate-shaped or box-shaped bracket, and the front surface of this flange is joined to the back surface (back surface) of the vertical wall 3b on the rear side of the protector 1a, or the bracket tip is directly connected to the vertical wall 3b. To the back of The joining is performed by appropriately combining welding and mechanical joining. Note that other protectors of the present invention, such as the protector 1b in FIG. 1B, can be similarly joined by these methods.
[0045]
The protector 1c shown in the front view in FIG. 4 shows a mode in which the protector 1c is joined and supported by the flange at the tip of the bracket. The protector 1c shown in FIG. 4 is provided with concave portions 8a and 8b which are recessed inward in the hollow portion 7 at two places in the vertical wall portion 3b on the rear side. The vertical wall portions of the recesses 8a, 8b and the flange 16 at the tip of the bracket 19 are joined by bolt fastening means 17a, 17b through the spaces 9a, 9b formed therethrough and the through holes 18a, 18b of the flange 16. Thus, the protector 1c is joined to and supported by the bracket 19. The bracket 19 has an appropriate plate-like or box-like structure, is connected to an upper body frame (not shown), and projects obliquely downward (front of the vehicle body) from the body frame.
[0046]
The cross-sectional shape of the protector 1c (square cross-section, point where the thickness of each of the horizontal wall portions 4a and 4b is thicker than each of the vertical wall portions 3a and 3b, etc.) is the same as that of FIG. This is the same as the protector 1a and the protector 1b in FIG. It does not matter whether both ends of the protector 1c are curved or the entire length is linear.
[0047]
The aluminum alloy satisfying the characteristics required for the protector of the present invention is a general-purpose alloy having a relatively high proof stress, such as AA to JIS 5000 series, 6000 series, and 7000 series, which is generally used for structural members of this kind. Selected from tempered aluminum alloys. However, among them, as described above, an Al-Si-Mg-based 6000 series aluminum alloy such as a 6063 general-purpose alloy, which is relatively easy to manufacture as a hollow material, is particularly preferable. However, as described above, when higher crush strength is required, an Al-Zn-Mg-based or Al-Zn-Mg-Cu-based 7000-based aluminum alloy may be used. These aluminum alloy materials are subjected to appropriate refining such as O 2, T4, T5, T6, and T7 to obtain desired proof stress and mechanical properties.
[0048]
The hollow aluminum alloy material constituting the protector of the present invention is preferably an extruded hollow material including the advantages described above. In the case of hot extrusion, the shape of a rectangular hollow cross section can be made uniform in the longitudinal (axial) direction of the hollow material. However, if possible, a hollow material obtained by forming a rolled plate of an aluminum alloy into a hollow shape and welding and joining the joints may be used.
[0049]
【The invention's effect】
According to the present invention, it is possible to provide a vehicle front under-run protector that increases the crushing strength of the aluminum alloy protector itself to the same level as that of the steel protector, and has a higher weight reduction effect than the steel protector. For this reason, the weight reduction of the truck body can be promoted, the use of the aluminum alloy material is further expanded, and the industrial value is great.
[Brief description of the drawings]
1A and 1B show an embodiment of a protector according to the present invention. FIG. 1A is a perspective view showing a protector having both ends curved, and FIG. 1B is a perspective view showing a linear protector.
FIG. 2 is a plan view showing one use mode of the protector according to the present invention.
FIG. 3 is a front view of FIG. 2;
FIG. 4 is a front view showing another embodiment of the protector according to the present invention.
[Explanation of symbols]
1: front underrun protector, 2: hollow material, 3: vertical wall, 4: horizontal wall,
5: curved portion, 6: central portion, 7: hollow portion, 8: concave portion, 9: space, 10: bumper,
11: body frame, 12: first cross member, 13: bracket,
14: front tire, 15: body, 16: flange, 17: bolt fastening means,
18: through hole, 19: bracket,
t _f: vertical wall portion of the _{thickness, L} f: vertical wall portion of the _{length, t} w: the lateral wall portion of the thickness,
L _w: the length of the lateral wall portion, L: the length of the protector,

Claims (6)

The cross section is made of an aluminum alloy hollow material having a rectangular cross section, and the thickness of the horizontal wall portion constituting the rectangular hollow cross section is set to 4 to 8 mm. A vehicle front underrun protector that is also thicker. When the thickness of the vertical wall portion _{t f,} the length and the thickness of the L _f and the lateral wall portion and _{t w,} a length of L _{w, t} f / t _w a is from 0.3 to 0.7, vehicle front underrun protector of claim 1 _{L f} / L _w is 0.8 to 1.2. The vehicle front underrun protector according to claim 1, wherein both ends of the hollow member in the axial direction are curved toward the rear of the vehicle. The vehicle front underrun protector according to any one of claims 1 to 3, wherein the aluminum alloy is any one of a 5000 series, a 6000 series, and a 7000 series aluminum alloy. The vehicle front underrun protector according to any one of claims 1 to 4, wherein a 0.2% proof stress of the aluminum alloy is 250 MPa or less. The vehicle front underrun protector according to any one of claims 1 to 5, wherein the hollow member is an extruded aluminum alloy member.

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