JP4045846B2 - Impact energy absorbing member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a collision energy absorbing member, and more specifically, a collision energy absorbing member that forms a part of a vehicle body frame structure made of a metal material and absorbs collision energy at the time of automobile collision by buckling in a member axial direction. About.
[0002]
[Prior art]
Among the frame structural parts of the automobile body, the front side frame 1 as shown in FIG. 5 and the rear side frame (not shown) arranged at the rear of the vehicle play an important role as energy absorbing members in the event of a car collision. Plays. In general, when the vehicle collides, the side frame is appropriately crushed to absorb the energy at the time of the collision and to secure a passenger living space in the cabin. For example, in the front side frame 1 shown in FIG. 5, a load (collision load) 2 input in the direction of the arrow at the time of a collision in the front is transmitted to the front side frame 1 via the bumper. When the vehicle is not crushed properly and energy cannot be absorbed, the load 2 at the time of collision is further transmitted to the rear cabin, and the passenger is damaged. Therefore, a member having high energy absorption capability is desired for the collision energy absorbing member such as the front side frame.
[0003]
In response to such a request, for example, Japanese Patent Application Laid-Open No. 4-310477 discloses a basic member extruded into a closed cross-sectional structure with a light metal, and is fitted into the basic member and compressed to at least the tip of substantially the same length. A member in which a double structure is formed by a deformation promoting portion, preferably a reinforcing member provided with a notch has been proposed. Also, in JP-A-11-29064 and JP-A-11-208519, ribs that are in contact with the inner surface of the hollow material are provided on the surface passing through the central axis of the hollow material by the extrusion process of the light metal material. A frame structure of a car body has been proposed.
[0004]
[Problems to be solved by the invention]
In order to increase the energy absorption amount at the time of collision, it is effective to increase the thickness of the material constituting the member. However, increasing the thickness of the components increases the weight of the vehicle and directly leads to a deterioration in fuel consumption. From the viewpoint of global environmental conservation, CO ₂ emission reduction activities that are being deployed worldwide, that is, lighter automobiles. It is not preferable from the viewpoint of conversion.
[0005]
As another method for increasing the energy absorption amount, there is a method for optimizing the cross-sectional shape of the member. Optimization of the cross-sectional shape is effective in that the amount of energy absorption per unit weight of the member can be increased without increasing the plate thickness of the member.
Against this background, a front side frame by extruding a light metal material typified by aluminum as described above has been proposed. According to this, a member having a closed cross-sectional structure having a partition wall formed by extrusion processing has an increased amount of energy absorption and a stable buckling shape compared to a member having a simple closed cross-section structure without a previous partition wall. This has the advantage that the amount of energy absorption and the buckling load during deformation are also stabilized.
[0006]
However, in extruded parts of light metal materials represented by aluminum, the material to be processed and the manufacturing cost are high, and the productivity is poor. Therefore, there is a problem that the parts themselves are expensive, and there are also methods for fastening with adjacent parts. There was a problem of becoming complicated.
In addition, for steel materials and the like that are most commonly used as frame materials for automobile bodies, it is possible to manufacture cross-sectional structural members having partition walls by a known method (for example, sheet metal processing), but the processing is complicated. In view of the necessity of a plurality of processes, there are problems in terms of manufacturing technology and cost.
[0007]
An object of the present invention is to solve these problems, and to provide a collision energy absorbing member for automobiles which is small and light, has a large amount of impact absorbed energy due to buckling in the axial direction of the member , and is inexpensive and excellent in productivity. And
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present inventors have repeatedly studied a structural member having a closed cross-sectional shape having a partition wall that can be manufactured easily and inexpensively, and have reached the present invention as described below.
(1) Among the body frame structural members of automobiles made of metal materials, a pressed steel sheet is closed in a cross-sectional shape in a collision energy absorbing member that absorbs collision energy during automobile collision by buckling in the member axial direction A plurality of first-type insertion members made of a circular tube or a square tube are press-fitted into an outer frame member that is welded in combination to form a partition made of the insertion member. The collision energy absorption member characterized by the above-mentioned.
(2) Instead of the first type consisting of the circular tube or the square tube, the second type formed by welding a pressed steel sheet in combination with a closed cross-sectional shape is used. Impact energy absorbing member.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The collision energy absorbing member of the present invention (member of the present invention) absorbs collision energy at the time of automobile collision by buckling in the member axial direction . For example, as shown in FIG. Fig. 1: af , where a is a reference example ) or a plurality of press-formed products 3 (two in this example) formed by pressing into a semicircular cross section (Fig. 1: g, h), resulting in a closed cross-sectional shape as combined, preferably at the flange portion 4, welding 9 and the outer frame member 5 ungated and, in the same member, several double filling a first type of inner insertion member comprising a circular pipe 6 or square tube 7 It is a member formed by inserting and forming a partition wall (internal partition wall) 8 made of the insertion member.
[0010]
The filling insertion referred to in the present invention, several inner insertion member multiple Upon insertion into the outer frame member, among the inner insertion member is other in an inscribed and / or Dosotowaku member to the outer frame member means inserts that as circumscribes the insertion member in the state of being blocked translation direction other than the insertion direction. Any welding method such as spot welding, laser welding, arc welding, or the like may be used as the method for welding 9 the press-formed products 3 to each other.
[0011]
As a result, a partition wall made of a circular tube or a square tube is formed in the outer frame member formed by welding a thin steel plate after press working, so it is easy to use without using conventional extrusion processing or complicated processing methods. A member having an internal partition can be manufactured. These members have the advantage of being able to buckle stably in the axial direction because Euler buckling hardly occurs in the lateral direction when a collision load is input because the lateral bending rigidity is strengthened by the internal partition. Yes.
[0012]
In addition, since the lateral bending rigidity of the members is increased as described above, the present invention is applied to automobile parts such as side sills, center pillars, front pillars, and roof rails that cause bending deformation at the time of side collision or frontal collision. Even when the invention is applied, as in the case of the front side frame, the energy at the time of the collision can be absorbed well, and the effect of improving the occupant safety at the time of the collision can be obtained.
[0013]
Furthermore, by filling and inserting a circular tube or a square tube into the outer frame member to form an internal partition wall, the member can be stably buckled in the axial direction as described above, as shown in FIG. As described above, it has been found in the experiments by the present inventors that the amount of energy absorption during the collision can be increased while the member is crushed and crushed.
FIG. 2 is a characteristic diagram showing a load-displacement curve when the present invention example (# 1) and the comparative examples (# 2), (# 3), and (# 4) are crushed in the member axial direction. Here, Example (# 1) of the present invention has the same form as FIG. 1 (c), Comparative Example (# 2) is a combination of a press-formed product 3 having a normal cross-sectional hat shape and welded 9, Comparative Example ( # 3) is a comparative example (# 2) welded with a reinforcing material 10 consisting of a press-molded product with a normal cross-sectional hat shape, and comparative example (# 4) is a round tube compared to comparative example (# 2) 6 is simply inserted (non-filled insertion) and welded 9. It should be noted that the thicknesses of the components (outer frame member, reinforcing material, circular tube) of the crushed member used here are the same, and the circumferences (members) of the respective components are the same so that each example has the same weight. The thickness center line length in the cross section perpendicular to the axial direction) was set.
[0014]
As shown in FIG. 2, the load characteristics at the time of axial crushing are shown in both the examples of the present invention and the comparative example. After the load that has increased to the initial peak load P immediately after the collision decreases with the start of buckling deformation, the buckling is performed. Along with the accordion-like progress of deformation, it appears to repeat a slight increase / decrease, and the initial peak load P is approximately the same level in any example. However, in the example of the present invention, a load level higher than that of the comparative example is obtained at a time when the minute increase / decrease is repeated with the bellows-like progress of the buckling deformation, and the energy absorption amount at the time of deformation evaluated by load displacement integration is large. I understand that.
[0015]
The reason is considered as follows. That is, in the present invention example, each of the internal partition walls formed by inserting and inserting an insertion member such as a circular tube interferes with each other when buckling deformed in a bellows shape in the member axial direction, whereas the comparative example (# In 2), there is no internal partition, so such mutual interference does not occur.In Comparative Examples (# 3) and (# 4), there are partition equivalent members but there are few contact points with other element members. Even if interference occurs, it will not be as large as the present invention. Further, when the insertion member is close to one side of the outer frame member as in (# 4), the cross-sectional shape is not symmetrical and is not stably crushed and easily bends in the lateral direction. Therefore, in the example of the present invention, the load level higher than that of the comparative example is reached in the bellows-like progress stage of buckling deformation.
[0016]
Further, in the present invention, for example, as shown in FIG. 3, a pressed steel sheet (press-formed product) is combined into a closed cross-sectional shape in place of the first type of insertion member formed of a circular tube or a square tube. The same effect can be obtained even if the second type of insertion member 5A formed by welding 9 is used.
In the case of the second type of insertion member having a quadrangular shape, the welding flange interferes with the outer frame member or the insertion member at the time of insertion. preferable. Further, the number of combinations of the press-formed products is not particularly limited as long as it is plural, but two is preferable from the viewpoint of reducing the press man-hour and the welding man-hour. This also applies to the outer frame member.
[0017]
On the other hand, the cross-sectional shape of the outer frame member is not limited to a substantially square shape combined with a hat shape or a substantially circular shape combined with a semicircular arc shape as shown in FIG. The same effect can be obtained even when the shape is polygonal or elliptical. The insertion member may be welded to the outer frame member by laser welding or the like, but in the present invention, it is fixed by press-fitting (regardless of type).
[0018]
Further, when the number of inserted insertion members is one, there is interference between deformations between this one and the outer frame member at the time of a collision. Because of the interference between the buckling deformations, the amount of energy absorption is further increased. Therefore, the filling insert number of the inner insertion member in the present invention shall be the plurality (not according to the type).
[0019]
Further, the present invention does not depend on the combination of the type, number, cross-sectional shape, and cross-sectional shape of the outer frame member of the insertion member, etc., even if the combination is not illustrated in FIGS. Similar effects can be expected. What kind of combination should be determined may be determined appropriately in consideration of the required energy absorption amount, member weight, and the like.
[0020]
【Example】
Members A to D having a cross-sectional shape perpendicular to the member axial direction in FIG. 4 were produced using a hot-rolled steel sheet having a thickness of 1.2 mm and a tensile strength of 440 MPa as a raw material. The axial length of each member was 300 mm.
The member A is a comparative example having no internal partition wall, which is a member obtained by spot-welding two of the above-mentioned raw materials press-molded in a cross-sectional hat shape into a closed cross-sectional shape. The cross-sectional dimensions of the member A were set to 120 mm each for the length and width of the rectangular portion and the length of the welding flange portion of 20 mm.
[0021]
The members B to D are formed by combining the two press-formed materials into a closed cross-sectional shape into a closed cross-sectional shape and spot-welded to form an outer frame member. The material is electro-welded in the outer frame member. This is an example of the present invention (member B is a reference example) in which a first type of insertion member composed of a circular pipe formed by the method is filled and inserted, and a partition is formed by the insertion member . The insertion of the insertion member into the outer frame member is performed by press fitting, and the two are not welded. The cross-sectional hat-shaped member forming the members B to D and the circumference of the insertion tube were calculated and set so that the members B to D had the same weight as the member A, respectively.
[0022]
A weight is caused to collide head-on at one end face in the axial direction of these members at a speed of 50 km / h, the generated load is measured with a load cell and the displacement of the collision end is measured with a laser displacement meter to obtain a load-displacement curve, The amount of energy absorbed by the member until the deformation (crush length in the axial direction) reached 150 mm was calculated by integrating the load in the range of 0 to 150 mm using the curve.
[0023]
FIG. 4 shows the energy absorption ratio of each member to member A. The amount of energy absorption increased in the order of A <B <C <D, and it was verified that the energy absorption capacity of the member of the present invention was high.
Next, members EG having a cross-sectional shape perpendicular to the member axial direction in FIG. 6 were produced using the same hot rolled steel sheet having a thickness of 1.2 mm and a tensile strength of 440 MPa as described above. The axial length of each member was 300 mm.
[0024]
The member E is a member that is spot welded by combining two pieces of the above-mentioned raw material pressed into a cross-sectional hat shape in the shape of a cross-sectional hat as in the case of the member A described in FIG. . The cross-sectional dimensions of the member E were set to 120 mm each for the length and width of the rectangular portion and the length of the welding flange portion 20 mm, as with the member A of FIG.
The members F and G are formed by combining two press-molded materials into a closed cross-sectional shape and spot-welded to form an outer frame member. The material is semicircular in cross-section within the outer frame member. Example of the present invention in which a second type of insertion member formed by combining two press-molded products into a closed cross-sectional shape and spot-welding is inserted and a partition wall is formed by the insertion member (however, the member F) Is a reference example) . The insertion of the insertion member into the outer frame member is performed by press fitting, and the two are not welded. The circumferential lengths of the cross-sectional hat-shaped member and the insertion member forming the members F and G were calculated and set so that the members F and G had the same weight as the member E, respectively.
[0025]
The weights were collided with one end face in the axial direction of these members at a speed of 50 km / h, the load-displacement curve was obtained by the method described above, and the amount of energy absorbed by the members until the deformation reached 150 mm was calculated.
FIG. 6 shows the ratio of energy absorption of each member to member E. The energy absorption amount increased in the order of E <F <G, and it was verified that the energy absorption capacity of the member of the present invention was high.
[0026]
【The invention's effect】
Thus, according to the present invention, it is possible to easily and inexpensively manufacture a member having high energy absorption capability at the time of a car collision, and it is possible to further reduce the weight of the vehicle as well as ensuring the safety of the passenger. Excellent effect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of the present invention (where (a) is a reference example) having a partition wall made of a first type of insertion member.
FIG. 2 is a characteristic diagram showing a load-displacement curve when the invention example (# 1) and the comparative examples (# 2, # 3, # 4) are crushed in the member axial direction.
FIG. 3 is a cross-sectional view showing an example of the present invention (a) and a reference example (b) having a partition wall made of a second type of insertion member.
4 is a graph showing the energy absorption ratio at the time of collision in Reference Example B, Invention Examples C and D, and Comparative Example A. FIG.
FIG. 5 is an explanatory diagram showing an example of a front side frame.
6 is a graph showing the energy absorption ratio at the time of collision in Reference Example F, Invention Example G and Comparative Example E. FIG.
[Explanation of symbols]
1 Front side frame 2 Load (collision load)
3 Press-formed product (Pressed thin steel plate)
4 Flange part 5 Outer frame member
5A Type 2 insertion member 6 Circular pipe (Type 1 insertion member)
7 Square tube (1st type insertion member)
8 Bulkhead (Internal Bulkhead)
9 Welding
10 Reinforcing material

Claims (2)

Among car body frame structural members of automobiles made of metal materials, a pressed steel sheet is combined into a closed cross-sectional shape in a collision energy absorbing member that absorbs collision energy during automobile collision by buckling in the axial direction of the member. A plurality of first-type insertion members made of a circular tube or a square tube are press-fitted into a welded outer frame member to form a partition made of the insertion member. A collision energy absorbing member.   2. The collision energy absorption according to claim 1, wherein, instead of the first type consisting of the circular tube or the square tube, the second type is formed by welding a pressed steel sheet in combination with a closed cross-sectional shape. Element.

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