Bumper energy absorber

Abstract

The present invention provides a bumper energy absorber. The purpose of the present invention is to absorb energy during a collision without causing the reaction force on pedestrians to be greater than a certain level. The bumper energy absorber (20) comprises: a main body (21) extending in the X direction and being simply compressed in the X direction by an impact; and a branch body (22) branching from the main body (21) to the rear of the vehicle body, and a fracture initiation portion (24) is provided at a branch portion (23) of the branch body (22) branching from the main body (21). The fracture initiation portion (24) induces fracture of the main body (21) and the branch body (22) caused by the impact.

Description

Technical Field

[0001] The invention relates to a bumper energy absorber. Background Art

[0002] Conventionally, a bumper system is provided at the front and rear of a vehicle body such as an automobile for the purpose of protecting the vehicle body and suppressing damage to passengers or objects hit during a collision. In particular, a bumper system has recently been developed that can reduce the load on the legs of pedestrians in a personal accident and reduce the value of injury to pedestrians.

[0003] Such a bumper system has an impact absorbing structure in which an impact absorbing member (bumper energy absorber) is disposed on the front surface of a bumper reinforcement disposed in the vehicle width direction.

[0004] Various shapes of bumper energy absorbers have been proposed. For example, the bumper energy absorber disclosed in Patent Document 1 has: a flat plate-shaped lower leg extending in the front-rear direction of the vehicle and arranged substantially horizontally; a flat plate-shaped upper leg provided above the lower leg; and a side portion connecting the front of the lower leg and the front of the upper leg.

[0005] In addition, the bumper energy absorber disclosed in Patent Document 2 has a first buffer member and a second buffer member that are divided into upper and lower parts. The first buffer member and the second buffer member are integrally connected to each other at the front position, and on the other hand, a space is formed between these buffer members at the rear position. In addition, the connection portion between the first buffer member and the second buffer member is formed so as to be broken when impacted from the front by a collision body.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-3688

[0009] Patent Document 2: Japanese Patent Application Publication No. 2008-94262 Summary of the invention

[0010] Problem that the invention aims to solve

[0011] The bumper energy absorber made of foam disclosed in Patent Documents 1 and 2 absorbs energy when the foam is compressed during a collision. However, when the foam is compressed to a certain extent, the bumper energy absorber may not be able to absorb the energy and the rebound against the pedestrian may become larger. Therefore, in order to protect pedestrians, there is room for improvement in the conventional bumper energy absorber in terms of absorbing energy without causing the reaction force to be larger than a certain extent.

[0012] An object of one technical solution of the present invention is to realize a bumper energy absorber capable of suppressing the reaction force toward a pedestrian during a collision.

[0013] Solutions for solving problems

[0014] In order to solve the above-mentioned problems, a technical solution of the present invention provides a bumper energy absorber, which is arranged in a bumper system inside a vehicle body, wherein the bumper energy absorber has: a flat plate-shaped main body, which extends along the front-to-rear direction of the vehicle body and is simply compressed in the front-to-rear direction due to the impact from the collision body; and at least one flat plate-shaped branch body, which branches from the main body to the rear of the vehicle body, and a fracture initiating portion is provided at the branch portion of the branch body that branches from the main body, and the fracture initiating portion induces fracture of the main body and the branch body caused by the impact.

[0015] Effects of the Invention

[0016] By adopting a technical solution of the present invention, the reaction force on pedestrians during a collision can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a perspective view schematically showing the structure of a vehicle equipped with a bumper system having a bumper energy absorber according to an embodiment of the present invention.

[0018] Figure 2 It is a cross-sectional view showing a schematic structure of a bumper energy absorber according to one embodiment of the present invention.

[0019] Figure 3 This is a cross-sectional view for explaining dimensions defining the bumper energy absorber according to one embodiment of the present invention.

[0020] Figure 4 401 (401A to 401D) is a diagram showing the impact buffering effect of the bumper energy absorber according to one embodiment of the present invention. Figure 4 402 (402A to 402C) is a diagram showing the impact buffering effect of a bumper energy absorber as a comparative example. Figure 4 The FS diagram is a graph showing the relationship between the load and displacement received by the collision body under the impact absorbing action of the bumper absorber of each of the embodiment of the present invention and the comparative example.

[0021] Description of Reference Numerals

[0022] 10. Bumper system; 20. Bumper energy absorber; 21. Main body; 22. Branch body; 23. Branch part; 24. Fracture initiation part; 100. Vehicle. DETAILED DESCRIPTION

[0023] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited thereto. The present invention is not limited to each structure described below, and various changes can be made within the scope of the claims. Figure 1 1 is a perspective view showing a schematic structure of a vehicle 100 equipped with a bumper system 10 having a bumper energy absorber 20 according to the present embodiment. In the present specification, the direction from the rear to the front of the vehicle 100 is referred to as the X direction, the vehicle width direction of the vehicle 100 is referred to as the Y direction, and the direction perpendicular to the X direction and the Y direction is referred to as the Z direction. The Z direction can also be referred to as a direction from the lower side to the upper side of the vehicle 100.

[0024] like Figure 1 As shown, the bumper system 10 includes a bumper energy absorber 20, a bumper reinforcement 30, and a bumper garnish 110. The bumper reinforcement 30 is mounted on the body of the vehicle 100. The bumper energy absorber 20 is arranged to abut against the front surface of the bumper reinforcement 30. The bumper garnish 110 is an exterior member of the vehicle 100, and covers the bumper energy absorber 20 and the bumper reinforcement 30.

[0025] The bumper energy absorber 20 has the following function: when a collision accident occurs, the bumper energy absorber 20 is deformed or crushed between the collision object such as the legs of a pedestrian and the bumper reinforcement 30, thereby absorbing the energy of the collision. The bumper energy absorber 20 has a function of reducing the reaction force to the collision object. The bumper energy absorber 20 is made of a material with excellent impact absorption.

[0026] The bumper reinforcement 30 is made of steel and is a member extending horizontally in the Y direction. The bumper reinforcement 30 bears the bumper energy absorber 20 that undergoes compression deformation. The bumper reinforcement 30 has, for example, a hollow cylindrical structure with a substantially rectangular shape. In such a hollow cylindrical structure, the bumper reinforcement 30 may also be provided with a reinforcement partition wall inside the hollow cylinder. In addition, the bumper reinforcement 30 functions as (i) a mounting seat for the bumper energy absorber 20 and (ii) a pedestal when the bumper energy absorber 20 is crushed to absorb impact.

[0027] The bumper trim 110 is a member that covers the bumper energy absorber 20 and the bumper reinforcement 30 from the outside of the vehicle body. The bumper trim 110 improves the appearance of the vehicle body 100. In addition, the bumper trim 110 has the following functions: protecting the bumper energy absorber 20 from the external environment and preventing the performance of the bumper energy absorber 20 from being degraded.

[0028] Preferably, the bumper garnish 110 is deformed or broken by a relatively small load when subjected to an impact load. Thus, the impact load is easily transmitted to the bumper energy absorber 20, and thus, the impact absorption performance of the bumper energy absorber 20 can be suppressed from being hindered by the bumper garnish 110. Therefore, the bumper garnish 110 is preferably a thin-walled molded body formed by injection molding or press molding of a synthetic resin or the like.

[0029] Next, the structure of the bumper energy absorber 20 will be described in more detail. Figure 2 It is a cross-sectional view schematically showing the structure of the bumper energy absorber 20 .

[0030] The bumper absorber 20 extends in the Y direction (vehicle width direction) and has a length close to the width of the vehicle 100. Also, the cross-sectional shape of the bumper absorber 20 along the X direction is substantially uniform in the Y direction. Figure 2 As shown, the bumper energy absorber 20 includes a trunk portion 21 and branch portions 22 .

[0031] The main body 21 is in the shape of a flat plate extending in the Y direction, and extends in the front-rear direction of the vehicle body, that is, the X direction. The main body 21 has a front surface 21a, a rear surface 21b, a lower surface 21c and an upper surface 21d. The front surface 21a functions as a collision surface that receives collision from a collision body in the event of a collision accident, and is located at the frontmost side of the entire bumper energy absorber 20. The rear surface 21b is a surface that abuts against the above-mentioned bumper reinforcement 30. In addition, the lower surface 21c is connected to both the front surface 21a and the rear surface 21b. The lower surface 21c is a surface that is inclined upward from the rear side to the front side. The upper surface 21d is the surface of the main body 21 opposite to the branch body 22.

[0032] The main body 21 is in a shape that is simply compressed in the front-to-back direction (i.e., the X direction) when the front surface 21a is hit by a collision body. The "simple compression" mentioned here means that under the action of the collision of the collision body, the main body 21 is compressed in the X direction without changing the orientation of the front surface 21a and the rear surface 21b.

[0033] When the main body 21 is hit by a collision body, it will not flip or fall over, but will simply be compressed. At this time, the main body 21 is compressed in such a way that the front surface 21a approaches the contact position I (equivalent to the position of the rear surface 21b) between the bumper reinforcement 30 and the bumper energy absorber 20. Here, the direction in which the front surface 21a approaches the contact position I is referred to as the compression direction. The compression direction can also be said to be the direction from the front side to the rear side, that is, the -X direction.

[0034] The branch portion 22 is a flat plate extending in the Y direction, and branches from the main portion 21 to the rear of the vehicle body. More specifically, the branch portion 22 branches from the front portion of the main portion 21 in a manner that inclines upward from the front side to the rear side. The branch portion 22 has a front inclined surface 22a, a rear surface 22b, and an inner surface 22c. The front inclined surface 22a is connected to the front surface 21a. And, the front inclined surface 22a is a surface that inclines upward from the front side to the rear side starting from the connection portion connected to the front surface 21a. In addition, the rear surface 22b is a surface that abuts against the above-mentioned bumper reinforcement 30. The rear surface 21b and the rear surface 22b are arranged at approximately the same position in the X direction. In addition, the inner surface 22c is the surface of the branch portion 22 that is opposite to the main portion 21.

[0035] In addition, in the bumper absorber 20, a fracture initiation portion 24 is provided at a branch portion 23 of the branch portion 22 that branches off from the main portion 21. The fracture initiation portion 24 has a function of initiating fracture between the main portion 21 and the branch portion 22 caused by an impact. Through the fracture initiation portion 24, when the front surface 21a of the bumper absorber 20 is impacted, the branch portion 22 is fractured from the main portion 21 while the main portion 21 is simply compressed. Therefore, in the bumper absorber 20, in the process of receiving an impact from a collision body and absorbing the collision energy, the branch portion 22 is fractured from the main portion 21 through the fracture initiation portion 24, and after the fracture, only the main portion 21 is impacted.

[0036] The fracture initiation portion 24 is not particularly limited as long as it is a structure that causes fracture of the main body 21 and the branch body 22 by impact. From the viewpoint of causing fracture of the main body 21 and the branch body 22 with a simpler structure, the fracture initiation portion 24 is preferably formed in a space formed by the main body 21 and the branch body 22.

[0037] For example, Figure 2 As shown, the fracture initiation portion 24 is a groove 25. The groove 25 is a structure extending in the Y direction. In addition, the groove 25 is a groove that is recessed from the branch portion 23 in the direction opposite to the compression direction of the main body 21. The "groove recessed in the direction opposite to the compression direction" mentioned here means a groove that is recessed in the direction opposite to the compression direction relative to the branch portion 22.

[0038] The groove 25 is formed by the surface 25a, the surface 25b, and the upper surface 21d of the trunk 21. The surface 25a is a surface extending toward the front inclined surface 22a relative to the inner surface 22c of the branch 22. The surface 25b is a surface constituting the front end of the surface constituting the groove 25, and is a surface connecting the upper surface 21d of the trunk 21 and the surface 25a. When viewed from the Y direction, the surface 25a and the surface 25b constitute a wall surface in the shape of an inverted L.

[0039] The inverted L-shaped wall portion has the function of causing the main body 21 and the branch portion 22 to break. When the collision load is applied to the front surface 21a of the bumper energy absorber 20, the main body 21 and the branch portion 22 are compressed and deformed in the -X direction. And, when the compression deformation proceeds, in the inverted L-shaped wall portion, stress is concentrated on the connecting portion 25c between the surface 25a and the surface 25b. And, when the bumper energy absorber 20 is further compressed and deformed, the main body 21 and the branch portion 22 are finally broken, and the branch portion 22 is separated from the main body 21.

[0040] Next, the dimensions defining the bumper energy absorber 20 will be described. Figure 3 This is a cross-sectional view for explaining a preferred example of defining the dimensions of the bumper energy absorber 20. In addition, for the sake of caution, it is mentioned that the bumper energy absorber according to one embodiment of the present invention is not limited to the dimensions and the like.

[0041] First, regarding the trunk portion 21, the inclination angle θ1 of the lower surface 21c relative to the horizontal plane can be set within the range of 0°≤θ1≤5°. In addition, the length L1, the height L2 of the trunk portion 21, and the length L3 can be appropriately set according to the allowable load of the bumper absorber 20. In addition, the length L1 is the length in the X direction from the front surface 21a to the surface 25b, and the length L3 is the length in the X direction from the front surface 21a to the rear surface 21b.

[0042] The length L1 is preferably in the range of 10% to 90% of the length L3, and more preferably in the range of 30% to 60% of the length L3. When the length L1 is in the above range, the deformation and breakage of the branch trunk can provide an effect of buffering the impact.

[0043] Regarding the groove 25, the inclination angles of the surface 25a and the surface 25b constituting the inverted L-shaped wall surface can be set as follows. That is, the inclination angle θ3 of the surface 25a relative to the horizontal plane can be set within the range of 0°≤θ3<90°. In addition, the inclination angle θ2 of the surface 25b relative to the vertical plane can be set within the range of -75°≤θ2<90°.

[0044] In addition, regarding the branch portion 22 , the inclination angle θ4 of the branch portion 22 with respect to the horizontal plane can be set within the range of 0°<θ4≤75°. Specifically, the inclination angle θ4 is the inclination angle of the inner surface 22 c of the branch portion 22 with respect to the horizontal plane.

[0045] In addition, the thickness b1 of the portion of the branch portion 22 located at the formation portion of the groove 25 is smaller than the thickness b2 of the portion of the branch portion 22 other than the formation portion of the groove 25. Specifically, the thickness b1 is defined as the length between the front side inclined surface 22a of the branch portion 22 and the connecting portion 25c between the surface 25a and the surface 25b of the groove 25. In addition, the thickness b2 is defined as the length between the front side inclined surface 22a and the inner surface 22c of the branch portion 22. In this way, since the thickness b1 is smaller than the thickness b2, the main portion 21 and the branch portion 22 can be broken.

[0046] Next, the impact absorbing function of the bumper energy absorber 20 will be described in further detail. Figure 4 401 (401A to 401D) are diagrams showing the impact absorbing effect of the bumper energy absorber 20 of the present embodiment. Figure 4 402 (402A to 402C) are diagrams showing the impact absorbing effect of the bumper energy absorber 20' as a comparative example. Figure 4 The F-S diagram is a graph showing the relationship between the load F (hereinafter sometimes referred to as the collision F) and the displacement S received by the collision body under the impact absorbing action of the bumper energy absorber 20 and the bumper energy absorber 20'. Figure 4 In the F-S line diagram, the F-S line of the bumper energy absorber 20 is represented by a solid line, and the F-S line of the bumper energy absorber 20' is represented by a dotted line. In addition, the "load on the collision body" refers to the value obtained by multiplying the (deceleration) acceleration applied to the collision body by the mass of the collision body in the case of a vehicle collision, and is sometimes simply referred to as a load. In addition, this load can also be said to be a reaction force.

[0047] In addition, Figure 4 401A to 401D of FIG. 4 are shown in a manner corresponding to the displacement S of the bumper energy absorber 20 in the FS diagram. Figure 4 402A to 402C are shown in a manner corresponding to the displacement S of the bumper energy absorber 20 ′ in the FS diagram.

[0048] In addition, if Figure 4 As shown in 402, compared with the bumper energy absorber 20, the bumper energy absorber 20' is a structure in which the space between the main body 21 and the branch body 22 is filled with constituent materials. That is, the bumper energy absorber 20' is in the shape of a substantially trapezoidal pentagonal prism extending in the Y direction.

[0049] When the bumper is impacted by a collision body from the front, the bumper energy absorber 20 Figure 4 The shape changes as shown in 401A to 401D, thereby relieving the collision (impact load) F. Figure 4As shown in FIG. 401A, when a collision F is applied to the front surface 21a by an impact body (not shown), the main body 21 and the branch body 22 expand in the up-down direction in such a manner that the branch body 22 is separated from the main body 21, and the bumper energy absorber 20 is compressed in the front-back direction. At this time, the front surface of the bumper reinforcement 30 abuts against both the main body 21 and the branch body 22. In this way, both the main body 21 and the branch body 22 receive the collision F and are compressed, so the load at the beginning of the collision increases.

[0050] Then, when the collision F is further applied, the fracture initiation portion 24 initiates the fracture, and the bumper energy absorber 20 breaks at the branch portion 23 of the branch portion 22 that branches off from the main portion 21, and separates into the fracture piece 20A and the fracture piece 20B. At this time, as shown in the F-S line graph, the load F received by the collision body gradually increases, and when it separates into the fracture piece 20A and the fracture piece 20B, the load peak (target load) is reached. In addition, the fracture piece 20A includes the branch portion 22, and the fracture piece 20B includes the main portion 21.

[0051] Furthermore, after being separated into the broken pieces 20A and the broken pieces 20B, the collision F is transmitted to the broken pieces 20B including the trunk 21, but not to the broken pieces 20A including the branch 22. As a result, after being separated into the broken pieces 20A and the broken pieces 20B, only the broken pieces 20B including the trunk 21 are subjected to the collision F and compressed. Furthermore, a stronger impact is applied to the broken pieces 20B, and the front surface 21a relatively retreats and absorbs the collision F. At this time, the load on the collision body drops to the lower limit of the load.

[0052] Then, if Figure 4 As shown in 401C, only the broken piece 20B receives the collision F. Furthermore, the broken piece 20B absorbs the collision F while compressing and deforming, and is compressed within the allowable load range. Figure 4 As shown in 401D, only the broken piece 20B including the main body 21 rebounds with respect to the collision F, so the rebound with respect to the impact can be suppressed to a low level. Therefore, the load received by the collision body will not be lower than the load lower limit, and will slowly rise and reach the target load, so the collision F can be mitigated.

[0053] Compared with the bumper energy absorber 20, the bumper energy absorber 20' is Figure 4 The shape changes as shown in 402A to 402C, thereby alleviating the collision (impact load) F. Figure 4 As shown in 402A to 402C, the bumper absorber 20' receives the collision F from the front surface 21'a and cushions the collision F only by compression deformation. Therefore, as shown by the dotted line of the FS graph, the load received by the collision body exceeds the target load.

[0054] As described above, the bumper absorber 20 of this embodiment can suppress the load on the collision body within the allowable load range from the load lower limit to the target load. That is, the bumper absorber 20 has the effect of absorbing energy during a collision without increasing the reaction force (load) on the pedestrian to a certain extent. Figure 3 The length L1 specified in the figure, the height L2 and the length L3 of the trunk portion 21, can set a target load and a load lower limit value suitable for the vehicle.

[0055] in addition, Figure 1 The bumper energy absorber 20 shown in the figure is a structure in which one branch portion 22 is provided with respect to one main portion 21. However, the bumper energy absorber of this embodiment only needs to have a structure in which at least one branch portion is provided as long as the above-mentioned effect is achieved, and is not limited to Figure 1 For example, in Figure 1 The bumper energy absorber of the present embodiment may also be a structure in which a plurality of branch portions 22 are provided with respect to one main portion 21 .

[0056] In addition, the material of the bumper energy absorber 20 is not particularly limited. Preferably, the bumper energy absorber 20 only needs to have at least the main body 21 made of foamed resin. The branch portion 22 is broken and separated from the main body 21 under the impact from the front, so the branch portion 22 can be made of a different material from the main body 21 or the same material as the main body 21. In the case where the material of the branch portion 22 is different from that of the main body 21, it is preferred that the material of the branch portion 22 is a flexible material that is compressed under the impact from the front.

[0057] When the trunk portion 21 and the branch portion 22 are made of the same foamed resin, the bumper absorber 20 is preferably constituted by a molded body in which the trunk portion 21 and the branch portion 22 are integrally molded.

[0058] The base resin of the foaming resin is not particularly limited, but is preferably a foamable thermoplastic resin. The thermoplastic resin is preferably at least one resin selected from the group consisting of polystyrene resins, polyolefin resins, and polyester resins.

[0059] As the polystyrene resin, there can be mentioned a resin containing a resin having a structural unit derived from a styrene monomer. As the styrene monomer, preferably styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, bromostyrene, chlorostyrene, vinyl toluene, vinyl xylene, etc. can be mentioned. As the resin having a structural unit derived from a styrene monomer, there can be mentioned (a) a homopolymer of a styrene monomer obtained by polymerizing one styrene monomer or (b) a copolymer of a styrene monomer obtained by polymerizing two or more styrene monomers. Preferably, a polystyrene resin that is a homopolymer of a styrene monomer and a copolymer of a styrene monomer, i.e., a resin having only a structural unit derived from a styrene monomer can be used.

[0060] As polyester resin, for example, aliphatic polyester resin, aromatic polyester resin, aliphatic aromatic polyester resin, etc. can be cited. As specific examples of polyester resin, for example, polyhydroxyalkanoate, polybutylene succinate (PBS), poly(butylene adipate-co-butylene terephthalate) (PBAT), and polyethylene terephthalate (PET) can be cited. In addition, polyhydroxyalkanoate is at least one selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxyoctadecanoate).

[0061] In addition, the polyolefin resin is not particularly limited, and polypropylene resin, polyethylene resin, etc. can be cited. As specific examples of monomers of polyolefin resins (hereinafter, sometimes referred to as olefin monomers), for example, ethylene, propylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, 1-octene, 1-decene, etc., α-olefins having 2 to 12 carbon atoms, etc. can be cited. These can be used alone or in combination of two or more.

[0062] In addition, other monomers copolymerizable with the olefin monomers include, for example, cyclopentene, norbornene, 1,4,5,8-dimethyl-1,2,3,4,4a,8,8a,6-octahydronaphthalene and other cyclic olefins; 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 1,4-hexadiene, methyl-1,4-hexadiene, 7-methyl-1,6-octadiene and other dienes, etc. These monomers may be used alone or in combination of two or more.

[0063] Specific examples of polyolefin resins include (i) polyethylene resins containing ethylene as a main component, such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, and linear low-density polyethylene, and (ii) polypropylene resins containing propylene as a main component. These polyolefin resins may be used alone or in combination of two or more.

[0064] Among these polyolefin resins, polyethylene resins containing ethylene as a main component are particularly effective in the bumper energy absorber of the present embodiment. In particular, polypropylene resins containing ethylene as a comonomer component and containing ethylene as an α-olefin are easily available and have excellent processability.

[0065] The polypropylene resin is not particularly limited as long as it contains propylene as a main monomer component, and examples thereof include propylene homopolymers, α-olefin-propylene random copolymers, α-olefin-propylene block copolymers, etc. These may be used alone or in combination of two or more.

[0066] In addition, as a foaming agent, volatile hydrocarbon foaming agents such as propane, isobutane, butane, pentane, and hexane; inorganic gases such as air, nitrogen, and carbon dioxide; and water can be used. When an inorganic gas is used, it is easy to obtain foamed particles with a higher foaming ratio, so carbon dioxide is preferred. These foaming agents can be used alone or in combination of two or more.

[0067] (Summarize)

[0068] The bumper energy absorber 20 of technical solution 1 of the present invention has the following structure, that is, the bumper energy absorber 20 is arranged in the bumper system 10 inside the vehicle body, wherein the bumper energy absorber 20 has: a flat main body 21, which extends along the front-to-rear direction (X direction) of the vehicle body and is simply compressed in the front-to-rear direction due to the collision F (impact) from the collision body; and at least one flat branch body 22, which branches from the main body 21 to the rear of the vehicle body, and a fracture initiating portion 24 is provided in the branch portion 23 of the branch body 22 that branches from the main body 21, and the fracture initiating portion 24 induces the fracture of the main body 21 and the branch body 22 caused by the collision F.

[0069] The bumper energy absorber 20 of the technical solution 2 of the present invention has the following structure, that is, based on the technical solution 1, the fracture inducing portion 24 is provided on the side of the space formed by the main body 21 and the branch body 22 .

[0070] The bumper energy absorber 20 of technical solution 3 of the present invention has the following structure, that is, based on technical solution 1 or 2, the fracture initiation portion 24 is a groove 25 recessed from the branch portion 23 in a direction opposite to the compression direction of the main body 21.

[0071] The bumper energy absorber 20 according to a fourth aspect of the present invention is configured as follows, that is, based on any one of the first to third aspects, at least the trunk portion 21 is made of a foamed resin.

[0072] The bumper energy absorber 20 of technical solution 5 of the present invention has the following structure, that is, based on any one of technical solutions 1 to 4, the inclination angle θ1 of the lower surface 21c of the trunk portion 21 relative to the horizontal plane is 0°≤θ1≤5°.

[0073] The bumper energy absorber 20 of technical solution 6 of the present invention has the following structure, that is, based on any one of technical solutions 1 to 5, the inclination angle θ4 of the branch portion 22 relative to the horizontal plane is 0°<θ4≤75°.

[0074] The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the protection scope of the present invention.

Claims

1. A bumper energy absorber, which is arranged in a bumper system having a bumper reinforcement in a vehicle body, in, The bumper absorber comprises: a main body of a flat plate extending in the front-rear direction of the vehicle body and having a front surface, the front surface being located at the frontmost side of the entire bumper absorber as a collision surface for receiving collision from a collision body, the main body being simply compressed in the front-rear direction by the impact from the collision body, the main body being made of a foamed resin; as well as at least one flat branch portion, which branches from the main portion toward the rear of the vehicle body, A fracture initiation portion is provided at a branch portion of the branch portion that branches off from the main portion, and the fracture initiation portion initiates fracture of the main portion and the branch portion caused by the impact. The fracture initiation portion is recessed from the branch portion in a direction opposite to the compression direction of the main portion. The branch portion and the main portion have rear surfaces that abut against the bumper reinforcement. The main body does not flip or overturn in the front-rear direction when the impact is received, but is simply compressed in a state where the rear surface abuts against the bumper reinforcement. When the specified load peak, i.e., the target load, is reached, the bumper energy absorber utilizes the fracture initiation portion to separate into a fracture piece including the branch portion and a fracture piece including the main portion. After separation, the fracture piece including only the main portion absorbs the impact while compressing and deforming within a range below the target load.

2. The bumper energy absorber according to claim 1, in, The fracture initiating portion is provided on a side of a space formed by the main stem and the branch stems.

3. The bumper energy absorber according to claim 1 or 2, in, An inclination angle θ1 of the lower surface of the trunk portion relative to a horizontal plane is 0°≤θ1≤5°.

4. The bumper energy absorber according to claim 1 or 2, in, The inclination angle θ4 of the branch trunk relative to the horizontal plane is 0°<θ4≤75°.

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