阅读说明：本技术 汽车用碰撞能量吸收部件 (Collision energy absorbing member for automobile ) 是由 樋贝和彦 盐崎毅 玉井良清 北村繁明 马渕直树 于 2019-12-12 设计创作，主要内容包括：本发明所涉及的汽车用碰撞能量吸收部件(1)在碰撞载荷从车身的前方或者后方输入时产生轴向压溃而吸收碰撞能量,其特征在于,具有：筒状部件(3),具有顶板部(5a)和一对纵壁部(5b)；封闭截面空间形成壁部件(9),在筒状部件(3)的内侧配设为跨越顶板部(5a)并且两端部与一对纵壁部(5b)的内表面接合,而在自身与筒状部件(3)的周壁部之间形成封闭截面空间；以及树脂(11),填充于该封闭截面空间,并含有橡胶改性环氧树脂和固化剂而成,树脂(11)的拉伸断裂伸长率为80％以上,与筒状部件(3)以及封闭截面空间形成壁部件(9)的粘合强度为12MPa以上,压缩公称应变10％时的压缩公称应力为6MPa以上。(The automotive collision energy absorbing member (1) according to the present invention absorbs collision energy by generating axial crush when a collision load is input from the front or rear of a vehicle body, and is characterized by comprising: a cylindrical member (3) having a top plate (5a) and a pair of vertical walls (5 b); a closed cross-sectional space forming wall member (9) which is disposed inside the tubular member (3) so as to straddle the top plate (5a) and has both ends joined to the inner surfaces of the pair of longitudinal wall portions (5b), thereby forming a closed cross-sectional space between itself and the peripheral wall portion of the tubular member (3); and a resin (11) which is filled in the closed cross-sectional space and contains a rubber-modified epoxy resin and a curing agent, wherein the resin (11) has a tensile elongation at break of 80% or more, an adhesive strength with the cylindrical member (3) and the closed cross-sectional space-forming wall member (9) of 12MPa or more, and a compressive nominal stress at a compressive nominal strain of 10% or more of 6MPa or more.)

1. An automotive impact energy absorbing member that is provided at the front or rear of a vehicle body and that absorbs impact energy by being crushed in the axial direction when an impact load is input from the front or rear of the vehicle body, comprising:

a cylindrical member formed of a steel sheet having a tensile strength of 590MPa or more and 1180MPa or less, and having a top plate portion and a pair of vertical wall portions continuous with the top plate portion;

a closed cross-sectional space forming wall member formed of a steel plate having a lower tensile strength than the tubular member, disposed inside the tubular member so as to straddle the top plate portion, having both end portions joined to inner surfaces of the pair of longitudinal wall portions, and forming a closed cross-sectional space between itself and a part of a peripheral wall portion of the tubular member; and

a resin filled in the closed cross-sectional space,

the resin is prepared from rubber modified epoxy resin and a curing agent,

the resin has a tensile elongation at break of 80% or more, an adhesive strength with the cylindrical member and the wall member forming the closed cross-sectional space of 12MPa or more, and a compressive nominal stress at a compressive nominal strain of 10% or more of 6MPa or more.

2. An automotive impact energy absorbing member that is provided at the front or rear of a vehicle body and that absorbs impact energy by being crushed in the axial direction when an impact load is input from the front or rear of the vehicle body, comprising:

a cylindrical member formed of a steel sheet having a tensile strength of 590MPa or more and 1180MPa or less, and having a top plate portion and a pair of vertical wall portions continuous with the top plate portion;

a closed cross-sectional space forming wall member formed of a steel plate having a lower tensile strength than the tubular member, disposed inside the tubular member so as to straddle the top plate portion, having both end portions joined to inner surfaces of the pair of longitudinal wall portions, and forming a closed cross-sectional space between itself and a part of a peripheral wall portion of the tubular member; and

a resin filled in the closed cross-sectional space,

the resin is prepared by the rubber modified epoxy resin,

the resin has a tensile elongation at break of 80% or more, an adhesive strength with the cylindrical member and the wall member forming the closed cross-sectional space of 12MPa or more, and a compressive nominal stress at a compressive nominal strain of 10% or more of 6MPa or more.

Technical Field

The present invention relates to an automotive crash energy absorbing member (crash energy absorption part for automotive vehicle), and more particularly, to an automotive crash energy absorbing member that absorbs crash energy by being crushed (axially crushed) in a longitudinal direction when a crash load (crash load) is input from the front or rear of a vehicle body.

Background

As a technique for improving the collision energy absorption performance of an automobile, there are many techniques for optimizing the shape, structure, material (materials), and the like of automobile parts. In recent years, there has been proposed a technique of foaming a large amount of resin (foamed resin) and filling the foamed resin into an automobile part having a closed cross section structure (closed cross section structure) to achieve both improvement in collision energy absorption performance and weight reduction of the automobile part.

For example, patent document 1 discloses a technique of filling a foam filling material into an automotive structural member having a structure in which top portions (top portions) of hat-shaped cross-section members (side sills), floor members (floor members), pillars (pilars), and the like are aligned in the direction and flanges are overlapped (folded) to form a closed space inside the automotive structural member, thereby increasing the bending strength (bending strength) and the torsional rigidity (torsion rigidity) of the automotive structural member with a minimum increase in weight and improving the rigidity (rigidity) and the collision safety (collision safety) of a vehicle body (automotive body).

Patent document 2 discloses a technique of improving vibration damping performance (stiffness performance) for suppressing transmission of vibration sound (vibration sound) and enhancing strength (strength), rigidity, and impact energy absorption, by fixing a highly rigid foam body by a compression reaction force (compression force) due to the filling and foaming of the highly rigid foam body when the highly rigid foam body is filled in an internal space of a closed cross-sectional structure such as a pillar in which hat-shaped cross-sectional members are opposed to each other and flange portions are combined.

Patent document 1: japanese patent laid-open publication No. 2006-240134

Patent document 2: japanese patent laid-open No. 2000-318075

According to the techniques disclosed in patent documents 1 and 2, by filling a foamed filler or a foam into the interior of an automobile part, the strength of the automobile part against bending deformation (bending deformation), the impact energy absorption of bending deformation by an impact, and the rigidity against torsional deformation (torsional deformation) can be improved, and deformation of the automobile part can be suppressed. However, there is a problem that, in an automobile part such as a front side frame (front side frame) or a crash box (crash box) which is an object of the present invention, when an impact load is input from the front or rear of an automobile and an axial crush occurs, buckling deformation (buckling deformation) in a bellows shape (bellows) is caused to absorb impact energy, and even when a technique of filling a foam filler or a foam into the inside of the automobile part is applied, it is difficult to improve the absorption of the impact energy.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide an automotive collision energy absorbing member such as a front side member or a crash box which can improve the effect of absorbing collision energy when a collision load is input from the front or rear of a vehicle body and axial crushing occurs in a corrugated shape.

An automotive impact energy absorbing member according to a first aspect of the present invention is an automotive impact energy absorbing member that is provided at a front portion or a rear portion of a vehicle body and that absorbs impact energy by being crushed in an axial direction when an impact load is input from a front side or a rear side of the vehicle body, the automotive impact energy absorbing member including: a tubular member (tubular member) formed of a steel sheet (steel sheet) having a tensile strength (tensile strength) of 590MPa class (MPa-class) or more and 1180MPa class or less, and having a top plate portion and a pair of vertical wall portions (side wall portions) continuous to the top plate portion; a closed cross-sectional space forming wall member formed of a steel plate having a lower tensile strength than the tubular member, disposed inside the tubular member so as to straddle the top plate portion, having both end portions joined to inner surfaces of the pair of longitudinal wall portions, and forming a closed cross-sectional space between itself and a part of a peripheral wall portion (circumferential wall portion) of the tubular member; and a resin filled in the closed cross-sectional space, the resin including a rubber-modified epoxy resin (rubber-modified epoxy resin) and a curing agent (curing agent), the resin having a tensile elongation at break (tensile) of 80% or more, an adhesive strength (adhesive strength) with the tubular member and the wall member forming the closed cross-sectional space of 12MPa or more, and a compression nominal stress (compression nominal stress) at a compression nominal strain (compression nominal strain) of 10% or more of 6MPa or more.

An automotive impact energy absorbing member according to a second aspect of the present invention is an automotive impact energy absorbing member that is provided at a front portion or a rear portion of a vehicle body and that absorbs impact energy by being crushed in an axial direction when an impact load is input from a front side or a rear side of the vehicle body, the automotive impact energy absorbing member including: a cylindrical member formed of a steel sheet having a tensile strength of 590MPa or more and 1180MPa or less, and having a top plate portion and a pair of vertical wall portions continuous with the top plate portion; a closed cross-sectional space forming wall member formed of a steel plate having a lower tensile strength than the tubular member, disposed inside the tubular member so as to straddle the top plate portion, having both end portions joined to inner surfaces of the pair of longitudinal wall portions, and forming a closed cross-sectional space between itself and a part of a peripheral wall portion of the tubular member; and a resin filled in the closed cross-sectional space, the resin containing a rubber-modified epoxy resin, the resin having a tensile elongation at break of 80% or more, an adhesive strength with the cylindrical member and the wall member forming the closed cross-sectional space of 12MPa or more, and a compressive nominal stress at a compressive nominal strain of 10% or more of 6MPa or more.

According to the present invention, in the process of the collision load being input from the front or rear of the vehicle body and the axial crush occurring, the buckling deformation can be repeatedly generated in a corrugated manner without decreasing the deformation resistance (deformation resistance) of the tubular member, and the effect of absorbing the collision energy can be improved.

Drawings

Fig. 1 is an explanatory view illustrating a structure of an automotive impact energy absorbing member according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view of the automotive impact energy absorbing member according to the present embodiment.

Fig. 3 is a view for explaining a method of testing the crush in the axial direction of the impact energy absorbing member for an automobile in the example.

Fig. 4 is a diagram showing the structure of a test specimen (test specimen) used for the axial crush test in the example (inventive example).

Fig. 5 is a diagram illustrating a method of measuring adhesive strength in the examples.

Fig. 6 is a diagram showing the structure of a test piece used in the axial crush test in the example (comparative example).

Fig. 7 is a graph showing the results of measurement of the collision load and the axial crush deformation (deformation volume) (stroke) in the axial crush test of the automotive crash energy absorbing member according to the comparative example in the example.

Fig. 8 is a graph showing the results of measurement of the collision load and the axial crush deformation amount (stroke) when the automotive crash energy absorbing member according to the invention example was subjected to an axial crush test using the test body as a test body in the example.

Detailed Description

An automotive impact energy absorbing member according to an embodiment of the present invention will be described below with reference to fig. 1 and 2. In the present specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description thereof is omitted.

As shown in fig. 1, an automotive crash energy absorbing member 1 according to the present embodiment includes a tubular member 3 including an outer part (outer parts)5 and an inner part (inner parts)7, and includes: a closed cross-sectional space forming wall member 9 provided at the front or rear of the vehicle body to absorb collision energy when a collision load is input from the front or rear of the vehicle body, and forming a closed cross-sectional space between itself and the outer member 5 that is a part of the peripheral wall portion of the tubular member 3; and a resin 11 filling a cross section of the closed cross-sectional space.

< cylindrical part >

The tubular member 3 is axially crushed to absorb collision energy, has a top plate portion 5a and a pair of vertical wall portions 5b continuous with the top plate portion 5a, and is formed in a tubular shape by joining, as shown in fig. 2, flange portions 5c of an outer member 5 having a hat-shaped cross-sectional shape formed by the top plate portion 5a, the vertical wall portions 5b, and the flange portions 5c and both side end portions of a flat inner member 7.

The outer member 5 and the inner member 7 constituting the tubular member 3 are each made of a steel sheet having a tensile strength of 590MPa class or more and 1180MPa class or less. Examples of the steel sheet include a cold rolled steel sheet (cold rolled steel sheet), a hot rolled steel sheet (hot rolled steel sheet), a zinc-based plated steel sheet (zinc-based plated steel sheet), a zinc alloy-based plated steel sheet (zinc alloy plated steel sheet), and an aluminum alloy-based plated steel sheet (aluminum alloy plated steel sheet).

The tubular member 3 is used for an automobile member having a closed cross-sectional structure such as a front side member extending in the vehicle body longitudinal direction at a left-right position of a front portion of the vehicle body to constitute a part of a vehicle body frame (automatic frame member), and a crash box provided at a front end or a rear end of the vehicle body frame, and the automobile member is arranged on the vehicle body such that an axial direction (longitudinal direction) of the tubular member 3 coincides with the vehicle body longitudinal direction.

< closed cross-section space forming wall member >

The closed cross-sectional space forming wall member 9 is formed of a steel plate having a lower tensile strength than the tubular member 3, and as shown in fig. 2, is a member having a substantially U-shaped cross-sectional shape (U-shaped cross section) that spans the top plate 5a and is disposed between the outer member 5 and the inner member 7 inside the tubular member 3, and has both ends joined to the pair of vertical wall portions 5b of the outer member 5, thereby forming a closed cross-sectional space between itself and the top plate 5a and the vertical wall portions 5b of the outer member 5, which is a part of the peripheral wall portion of the tubular member 3.

The vertical wall portion 5b and both end portions of the closed cross-sectional space forming wall member 9 are joined (joint) by spot welding or the like, for example. The closed cross-sectional space formed between the closed cross-sectional space forming wall member 9 and the outer member 5 is a space formed such that the cross-sectional shape in the direction intersecting the axial direction of the tubular member 3 shown in fig. 1 is a closed cross-section and the closed cross-section is continuous along the axial direction of the tubular member 3.

< resin >

The resin 11 is filled in the closed cross-sectional space formed between the closed cross-sectional space forming wall member 9 and the outer member 5.

The resin 11 contains a rubber-modified epoxy resin and a curing agent (curing agent), and the external member 5 and the closed-cross-sectional-space forming wall member 9 can be bonded to each other by utilizing the bonding ability (adhesive capacity) of the resin 11 itself by performing heat treatment (heat treatment) at a predetermined temperature and time. The resin 11 has physical properties (property) of a tensile elongation at break of 80% or more, an adhesive strength of 12MPa or more with the tubular member 3 and the closed cross-sectional space forming wall member 9, and a compression nominal stress of 6MPa or more at a compression nominal strain of 10%. These physical properties are values obtained by heat-treating the resin 11.

The tensile elongation at break, the adhesive strength, and the compressive nominal stress may be values determined by the following methods.

Elongation at break by tensile

Uncured resin was put between 2 steel plates adjusted to a predetermined gap, and the steel plates were heated and cured under predetermined conditions, and the steel plates were peeled off to prepare a flat resin, and the flat resin was processed into a predetermined shape to prepare a test piece. Next, a tensile test was performed at a predetermined tensile rate until the resin was broken, and the elongation between the gauge lines at the time of the resin breaking was measured. Then, the tensile elongation at break was determined as a value in percentage obtained by dividing the measured elongation between the gauge lines at the time of resin break by the initial distance between the gauge lines.

Adhesive Strength

Uncured resin was put between 2 steel plates adjusted to have a predetermined gap, and the resin was cured by heating under predetermined conditions to prepare a test piece. Next, the test piece was subjected to a tensile test at a predetermined tensile rate, and the load (load) at the time of fracture of the steel sheet and the resin was measured. Then, the measured load at the time of fracture was divided by the area of the bond between the steel plate and the resin (shear adhesive strength), and the obtained value was used as the adhesive strength (adhesive strength).

Nominal compressive stress

Uncured resin was put between 2 steel plates adjusted to a predetermined gap, and the steel plates were heated and cured under predetermined conditions, and peeled off to prepare a flat resin. Next, the flat resin was cut out in a cylindrical shape to prepare a test piece. Then, the circular surface of the test piece was defined as a compression surface, and a value obtained by dividing a load when the test piece was compressed to a nominal strain of 10% at a predetermined test speed by the initial cross-sectional area of the test piece was defined as a compression nominal stress.

The reason why the type and physical properties of the resin 11 are defined as described above in the automobile impact energy absorbing member 1 according to the present embodiment is as follows. First, when a collision load is input to the tubular member 3 and the axial crushing deformation occurs in a corrugated shape, the resin 11 is heat-cured by a heat treatment to adhere to the tubular member 3 and the closed cross-sectional space forming wall member 9 with an adhesive strength of 12MPa or more, and thus the resin 11 can deform following the deformation of the tubular member 3.

The tensile elongation at break is 80% or more, and therefore, when the resin 11 deforms following the crushing deformation in the axial direction of the tubular member 3, the resin 11 itself can be prevented from breaking.

The adhesive strength is 12MPa or more, and thus, it is possible to prevent a buckling resistance (buckling resistance) and a deformation resistance from being reduced due to the separation of the resin 11 from the cylindrical member 3 and the closed cross-sectional space forming wall member 9 during the axial crushing of the cylindrical member 3.

Since the compressive nominal stress at a compressive nominal strain of 10% is 6MPa or more, the resin 11 itself can have a sufficient proof stress (yield strength) to the extent that it is not crushed and damaged even if the tubular member 3 is deformed in a corrugated shape during the axial crushing.

Then, the kind and composition (composition) of the rubber-modified epoxy resin and the curing agent, and the temperature and time of the heat treatment may be appropriately adjusted so that the tensile elongation at break, the adhesive strength, and the compressive nominal stress of the resin 11 fall within the above ranges.

Further, as the curing agent, polyamine (aliphatic polyamine), aromatic amine (aromatic polyamine), aromatic polyamine (aromatic polyamine), polyamide amine (polyamine)), acid anhydride (acid anhydride curing agent), phenol-based curing agent, thiol-based curing agent, dicyandiamide (dicyandiamide) as a latent curing agent (latent curing agent), imidazole compound (imidazole compound), ketimine compound (ketimine compound), organic acid hydrazide (organic acid hydrazide), and the like are preferable, and the curing agent is optimally selected depending on the use environment, the reaction temperature, and the like.

As described above, in the automotive impact energy absorbing member 1 according to the present embodiment, in the process in which the impact load is input to the tubular member 3 and the tubular member 3 is crushed in the axial direction, the resin 11 can increase the buckling resistance without separating from the tubular member 3 and the closed cross-sectional space forming wall member 9, and can increase the impact energy absorbing performance by repeatedly buckling the tubular member 3 in a corrugated shape without decreasing the deformation resistance of the tubular member 3.

In the above description, the resin 11 is obtained by adding a rubber-modified epoxy resin and a curing agent after a heat treatment. However, depending on the amount of the curing agent to be filled into the closed cross-sectional space formed between the wall part (wall part)9 and the outer member 5, which is formed in the closed cross-sectional space (closed cross section space), the curing agent may not remain in the resin 11 after the heat treatment at a predetermined temperature and for a predetermined time or may not be detected.

Therefore, as another aspect of the automotive impact energy absorbing member 1 according to the embodiment of the present invention, the resin 11 after the heat treatment may be subjected to a heat treatment at a predetermined temperature and for a predetermined time period so as to bond the exterior member 5 and the closed cross-sectional space forming wall member 9 by utilizing the bonding ability of the resin 11 itself without containing or without detecting a curing agent.

Even when the curing agent is not contained or detected in the resin 11 after the heat treatment, the physical properties thereof are such that the tensile elongation at break is 80% or more, the adhesive strength with the cylindrical member 3 and the closed cross-sectional space forming wall member 9 is 12MPa or more, and the compression nominal stress at 10% compression nominal strain is 6MPa or more. Therefore, the kind and composition of the rubber-modified epoxy resin and the curing agent to be filled into the closed cross-sectional space before the heat treatment, and the temperature and time of the heat treatment may be appropriately adjusted so that the tensile elongation at break, the adhesive strength, and the compressive nominal stress of the resin 11 fall within the above ranges.

If the resin 11 containing the rubber-modified epoxy resin and containing no or no curing agent is within the above-described range of physical properties, the resin 11 can increase the buckling resistance without separating from the tubular member 3 and the closed cross-sectional space forming wall member 9 in the process of the collision load being input to the tubular member 3 and the axial crushing occurring, and can repeatedly buckle the tubular member 3 in a corrugated shape without decreasing the deformation resistance of the tubular member 3, and can improve the absorption of collision energy.

An experiment for confirming the effect of the automotive impact energy absorbing member according to the present invention was performed, and the result will be described below.

The test was conducted by performing an axial crush test using the automobile crash energy absorbing member according to the present invention as a test body, and as shown in fig. 3, the axial crush test was conducted by measuring a load-stroke curve indicating that a test body was long (axial length L of the test body 31) by inputting a load at a test speed of 17.8m/s in the axial direction of the test body 31 and photographing a deformation state by a high-speed camera₀) The relationship between the load at 80mm axial crush deformation from 200mm to 120mm and the axial crush deformation amount (stroke). Then, the absorption energy of the stroke 0 to 80mm is obtained from the measured load-stroke curve.

Fig. 4 shows the structure and shape of a test piece 31 as an inventive example. The invention example was an axial crush test performed using the automobile impact energy absorbing member 1 (fig. 1 and 2) according to the embodiment of the invention described above as a test body 31. The test piece 31 includes a tubular member 3 formed by spot welding an outer member 5 and an inner member 7, a closed cross-sectional space is formed between the outer member 5 and the closed cross-sectional space forming wall member 9, and the entire area of the closed cross-sectional space is filled with a resin 11. The gap height between the external member 5 and the closed cross-sectional space-forming wall member 9 was set to 1mm, 3mm, and 8mm (fig. 4 (a) to (c)).

The outer member 5 is a steel sheet having a tensile strength of 590MPa to 1180MPa and a thickness of 1.2mm or 1.4mm, and the inner member 7 is a steel sheet having a tensile strength of 590MPa and a thickness of 1.2 mm. Further, as the closed cross-sectional space forming wall member 9, a steel plate having a tensile strength of 270MPa and a plate thickness of 0.5mm was used.

The resin 11 is a resin obtained by heat-treating a rubber-modified epoxy resin and a curing agent at a predetermined heating temperature and heating time, and the values of the tensile elongation at break, the adhesive strength, and the compressive nominal stress of the resin 11 after the heat treatment are within the ranges of the present invention. Here, the tensile elongation at break, the adhesive strength, and the compressive nominal stress were separately determined by the following test methods.

< tensile elongation at Break >

The gap between 2 steel plates was adjusted to 2mm, uncured resin was put therebetween, and the steel plates were heated and cured under conditions of 180 ℃ by 20 minutes, and peeled off to prepare flat resin having a thickness of 2 mm. Then, the flat plate-like resin was processed into a dumbbell shape (dumbbell shape) (JIS6 dumbbell) to prepare a test piece, a tensile test (tensile test) was performed at a tensile speed (tensile speed) of 2mm/min until the resin was broken, and an inter-line elongation (elongation between marked lines) at the time of the resin breaking was measured. Then, the value obtained by dividing the measured elongation between the gauge lines at the time of resin fracture by the initial distance between gauge lines (═ 20mm) is displayed as a percentage as a tensile elongation at break.

< shear adhesion Strength >

As shown in fig. 5, the cover 23 and the cover 25 were formed of Steel Plates (SPCC) having a width of 25mm, a thickness of 1.6mm, and a length of 100mm, uncured resin 27 was provided at an adhesive portion (adhesive portion) (width of 25mm, length of 10mm), and a test piece obtained by heat curing under a condition of maintaining 180℃ × 20 minutes in a state of being adjusted to a thickness of 0.15mm was used as the test piece 21. Next, a tensile test was performed on the test piece 21 at a tensile rate of 5mm/min until the covering (adheend) 23 or the covering 25 and the resin 27 were broken, and the load at the time of breakage was measured. Then, the breaking bond strength was determined as a value obtained by dividing the load at the time of breaking by the area of the bonded portion (bonded area: width 25 mm. times.length 10 mm).

< compressive nominal stress >

The gap between 2 steel plates was adjusted to 3mm, uncured resin was put therebetween, and the steel plates were heated and cured under conditions of 180 ℃ for 20 minutes, and peeled off to prepare flat resin test pieces having a thickness of 3 mm. Next, a material cut out from the flat plate-like resin test piece in a cylindrical shape having a diameter of 20mm was used as a test piece. Then, the circular surface of the test piece having a diameter of 20mm was defined as a compression surface, and the value obtained by dividing the load when the test piece was compressed to a nominal strain of 10% at a test speed of 2mm/min by the initial cross-sectional area of the test piece was defined as a compression nominal stress.

In the present example, as a comparative example, a case where a test piece 33 (fig. 6) having the same shape as the cylindrical member 3 and the closed cross-sectional space forming wall member 9 of the invention example and not filled with resin was used, and a case where the physical properties of the resin 11 in the test piece 31 having the same shape as the invention example were out of the range of the present invention were used, and the axial crushing test was performed in the same manner as the invention example. Table 1 shows the structure of the test pieces, the type of resin, the tensile elongation at break, the adhesive strength, and the compression nominal stress at 10% compression nominal strain, which are the inventive examples and the comparative examples.

[ Table 1]

In table 1, in the invention examples 1 to 7, the tensile strength (590MPa class or more and 1180MPa class or less) of the steel sheet for the outer member 5 and the inner member 7 constituting the tubular member 3, the tensile strength (270MPa class) of the steel sheet for the wall member 9 formed by closing the cross-sectional space, the kind of the resin 11, the tensile elongation at break, the adhesive strength, and the compressive nominal stress are all set within the scope of the invention shown in the above-described embodiments.

In addition, in the invention examples 1 to 4, the curing agent remains in the resin 11 after the heat treatment is performed at the predetermined heating temperature and the predetermined heating time. In addition, in the invention examples 5 to 7, the amount of the curing agent was smaller than in the invention examples 1 to 4, and the curing agent was not left or detected in the resin 11 after the heat treatment at the predetermined heating temperature and the predetermined heating time.

For these, the test piece 33 not filled with resin was used in comparative examples 1 to 4, and the test piece 31 in which the type of the resin 11 was epoxy resin or urethane resin and at least one of tensile elongation at break, adhesive strength, and compressive nominal stress was out of the range of the present invention was used in comparative examples 5 to 7.

Fig. 7 and 8 show the measurement results of load-stroke curves (load-stroke curves) when the axial crushing test was performed using the test body 33 according to comparative example 1 and the test body 31 according to invention example 1, respectively. Fig. 7 and 8 are load-stroke curves in which the horizontal axis represents the stroke (mm) of the deformation amount of the test body in the axial direction from the start of the collision, and the vertical axis represents the load (kN) input to the test body. The absorption energy shown in the graph is the absorption amount of the collision energy at a stroke of 0 to 80 mm.

Comparative example 1 shown in fig. 7 is a result of a test piece 33 (fig. 6) not filled with resin, and the load input to the test piece 33 shows a maximum value (about 300kN) immediately after the input starts, and thereafter, the value of the load fluctuates together with the buckling of the peripheral wall portion of the cylindrical member 3. Then, the absorbed energy at the end of the test when the stroke reached 80mm was 6.5 kJ.

The invention example 1 shown in fig. 8 is a result of the test piece 31, and the test piece 31 is formed by filling the resin 11 into the closed cross-sectional space formed between the outer member 5 and the closed cross-sectional space forming wall member 9, and the tensile elongation at break (═ 80%), the adhesive strength (═ 12MPa), and the compressive nominal stress (═ 6MPa) at the compressive nominal strain of 10% are within the range of the present invention. According to the load-stroke curve shown in fig. 8, the maximum load immediately after the start of load input was about 400kN, which was significantly higher than that of comparative example 1 described above. When compared with comparative example 1, the deformation load at a stroke of 10mm or less is stable and changes at a high value. The absorption energy at a stroke of 0 to 80mm was also significantly improved to 13.1kJ as compared with comparative example 1.

As described above, in invention example 1, by filling the resin 11 between the outer member 5 and the closed cross-sectional space forming wall member 9 and setting the tensile elongation at break, the adhesive strength, and the compressive nominal stress within the ranges of the present invention, the buckling resistance (buckling strength) during the axial crushing process is increased, the deformation resistance of the resin 11 is increased without peeling, and the corrugated compression deformation (compression deformation) is generated, thereby improving the absorption of the collision energy.

Next, the axial crush test was performed while changing the structure, the kind of resin, and the adhesive strength of the test body used for the axial crush test, and the measurement results of the absorbed energy at a stroke of 0 to 80mm and the weight of the test body are shown in table 1 listed below.

The test piece weight in table 1 is the sum of the weights of the outer member 5, the inner member 7, the closed cross-sectional space forming wall member 9, and the resin 11 in the test piece 31 filled with the resin 11. On the other hand, in the test piece 33 not filled with resin, the total of the respective weights of the outer member 5, the inner member 7, and the closed cross-sectional space forming wall member 9 was obtained.

As shown in FIG. 8, the absorption energy in invention example 1 was 13.1kJ, which is significantly higher than the absorption energy in comparative example 1 of 6.5 kJ. In addition, even in comparison with the absorption energy (═ 8.5kJ) in comparative example 4 in which a steel sheet (1180MPa grade) having a tensile strength higher than that in comparative example 1 was used for the outer member 5, the absorption energy was significantly improved in inventive example 1.

The weight of the test body in inventive example 1 was 1.28kg, which was increased from that in comparative example 1 in which no resin was filled (1.06 kg). However, in inventive example 1, the absorbed energy per unit weight divided by the weight of the test body was 10.2kJ/kg, which was higher than that in comparative example 1 (6.1 kJ/kg).

In the invention example 2, a test piece 31 (fig. 4 (c)) in which the thickness of the resin 11 was 1mm smaller than that of the invention example 1 was used. The absorption energy in inventive example 2 was 9.8kJ, which was significantly higher than that in comparative example 1(═ 6.5 kJ). The weight of the test piece in invention example 2 was 1.12kg, which was lighter than that in invention example 1. The energy absorbed per unit weight in invention example 2 was 8.5kJ/kg, which was higher than that in comparative example 1 (6.1 kJ/kg).

In invention example 3, a test piece 31 (fig. 4 (c)) having a tensile strength of 1180MPa class and a resin 11 thickness of 1mm was used as a steel sheet for the outer member 5. The absorption energy in invention example 3 was 12.6kJ, which was significantly higher than that in comparative example 4(═ 8.5 kJ). The weight of the test piece in invention example 3 was 1.13kg, which was lighter than that in invention example 1. In addition, the absorption energy per unit weight in invention example 3 was 11.2kJ/kg, which was higher than that in comparative example 4(═ 7.9 kJ/kg).

The invention example 4 is an example in which a test piece 31 (fig. 4 (b)) having a tensile strength of 590MPa class and a thickness of the resin 11 of 3mm is used as a steel sheet for the outer member 5. The absorption energy in invention example 4 was 10.1kJ, which was significantly higher than that in comparative example 1(═ 6.5 kJ). The weight of the test piece in invention example 4 was 1.19kg, which was lighter than that in invention example 1. In addition, the energy absorbed per unit weight in invention example 4 was 8.5kJ/kg, which was higher than that in comparative example 1 (6.1 kJ/kg).

The invention example 5 is an example in which a test piece 31 (fig. 4 (a)) having a tensile strength of 590MPa class and a thickness of 8mm of a resin 11 is used as a steel sheet for the outer member 5. The absorption energy in invention example 5 was 13.1kJ, which was significantly higher than the absorption energy in comparative example 1, which was 6.5 kJ. In addition, even in comparison with the absorption energy (═ 8.5kJ) in comparative example 4 in which a steel sheet (1180MPa grade) having a tensile strength higher than that in comparative example 1 was used for the outer member 5, the absorption energy was significantly improved in inventive example 5.

In invention example 6, a test piece 31 (fig. 4 (c)) was used in which the tensile strength of the steel sheet used for the outer member 5 was 1180MPa class and the thickness of the resin 11 was 1 mm. The absorption energy in invention example 6 was 12.6kJ, which was significantly higher than that in comparative example 4(═ 8.5 kJ). The weight of the test body in invention example 6 was 1.12kg, which was lighter than that in invention example 1. In addition, the absorption energy per unit weight in invention example 6 was 11.2kJ/kg, which was higher than that in comparative example 4(═ 7.9 kJ/kg).

In the invention example 7, a test piece 31 (fig. 4 (b)) having a tensile strength of 590MPa class and a resin 11 thickness of 3mm was used as a steel sheet for the outer member 5. The absorption energy in inventive example 7 was 10.1kJ, which was significantly higher than that in comparative example 1(═ 6.5 kJ). The weight of the test piece in invention example 7 was 1.19kg, which was lighter than that in invention example 1. In addition, the energy absorbed per unit weight in invention example 7 was 8.5kJ/kg, which was higher than that in comparative example 1 (6.1 kJ/kg).

Comparative example 1A test piece 33 (FIG. 6) not filled with resin was used, and the weight of the test piece was 1.06 kg. Further, as shown in FIG. 7, the absorbed energy was 6.5kJ, and the absorbed energy per unit weight was 6.1 kJ/kg.

Comparative example 2 is an example in which a steel sheet having a thickness of 1.4mm was used for the outer member 5 in the test piece 33 having the same shape as in comparative example 1, and the test piece weighed 1.17 kg. The absorbed energy in comparative example 2 was 7.0kJ, the absorbed energy per unit weight was 6.0kJ/kg, and the absorbed energy was increased as compared with comparative example 1, but it was inferior to inventive examples 1 to 7.

Comparative example 3 is an example in which a steel sheet having a tensile strength of 980MPa class was used for the outer member 5 in the test piece 33 having the same shape as that of comparative example 1, and the test piece weight was 1.06 kg. The energy absorbed in comparative example 3 was 8.1kJ and the energy absorbed per unit weight was 7.6kJ/kg, which were increased from those in comparative example 1, but were inferior to those in inventive examples 1 to 7.

Comparative example 4 is an example in which a steel sheet having a tensile strength of 1180MPa class was used for the outer member 5 in the test body 33 having the same shape as that of comparative example 1, and the test body weight was 1.07 kg. The absorbed energy in comparative example 4 was 8.5kJ and the absorbed energy per unit weight was 7.9kJ/kg, both of which were increased compared with comparative example 1, but which were inferior to inventive examples 1 to 7.

In comparative examples 5, 6 and 7, a test piece 31 (fig. 4) was used, and this test piece 31 had the same shape as the test piece 31 according to invention example 2, but the type of resin or at least one of the tensile elongation at break, the adhesive strength and the compressive nominal stress of the resin was out of the range of the present invention. The absorption energy and the absorption energy per unit weight in comparative example 5, comparative example 6, and comparative example 7 were less than those in any of invention examples 1 to 7.

Above, the following is shown: according to the automotive impact energy absorbing member of the present invention, the impact energy absorbing performance can be improved when an impact load is input in the axial direction and the crush occurs in the axial direction.

Industrial applicability of the invention

According to the present invention, it is possible to provide an automotive collision energy absorbing member such as a front side member or a crash box which can improve the effect of absorbing collision energy when a collision load is input from the front or rear of a vehicle body and axial crushing occurs in a corrugated shape.

Description of the reference numerals

An impact energy absorbing member for an automobile; a tubular member; an external component; a roof portion; a longitudinal wall portion; a flange portion; an inner component; closing the cross-sectional space to form a wall member; a resin; a test piece; a covering; a covering; a resin; a test body; a test body.