JP2019093920A - Underrun protector - Google Patents

Abstract

To provide an underrun protector of which weight saving can be promoted without reducing impact absorption performance.SOLUTION: This underrun protector has: a bumper beam 2 of a hollow square cross section of which both ends are opened; a thick part 4 formed at four corners of an opening 3 of the bumper beam 2; a cap screw hole 5 which is formed on the thick part 4 from the opening 3 so as not to penetrate an inner face of the bumper beam 2; and an end cap 8 which is mounted to the opening 3 of the bumper beam 2 by a bolt 6 which is screwed into the cap screw hole 5, has a convexed fitting part 7 which is inserted in the opening 3, and tightly closes the opening 3. When the bumper beam 2 receives an impact and is deformed, a part of an impact load F is absorbed by a repulsive force R2 of air which is compressed in association with reduction in an internal volume of the bumper beam 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an underrun protector mounted on the front and rear of a vehicle such as a truck.

  At the front and rear of a vehicle such as a truck, an underrun protector is provided to prevent the passenger vehicle from diving under the vehicle at the time of a collision with the passenger vehicle. As an underrun protector, one in which a bumper beam of hollow square cross section is attached to a vehicle body frame of a vehicle via an attachment stay is known.

  Conventional underrun protectors receive the collision load due to the stiffness of the bumper beam. Therefore, in order to receive a large collision load defined by the law, the thickness of the bumper beam of hollow square section is increased or horizontal rib is provided inside the bumper beam of hollow square section. It was necessary to set it as "the cross section of the shape of an eye" (refer patent document 1).

Patent No. 5795332

  However, in order to enhance the shock absorption performance in this way, the thickness of the bumper beam of the hollow square cross section is increased or horizontal ribs are provided inside the bumper beam of the hollow square cross section Increasing the stiffness of the bumper beam increases the weight of the underrun protector.

  Therefore, an object of the present invention is to provide an underrun protector capable of promoting weight reduction without degrading the shock absorbing performance.

  According to the present invention invented to achieve the above-mentioned object, the bumper beam having a hollow square cross section opened at both ends, thick portions formed at the four corners of the opening of the bumper beam, and the thick portion A cap screw hole formed so as not to penetrate the inner surface of the bumper beam, and a convex fitting portion attached to the opening of the bumper beam with a bolt screwed into the cap screw hole and inserted into the opening, And an end cap for sealing the part, and when the bumper beam is deformed due to an impact, a part of the impact load is absorbed by the repulsive force of the air compressed as the internal volume of the bumper beam decreases. An under-run protector is provided.

  In the underrun protector according to the present invention, a gasket or a sealing agent may be interposed between the opening of the bumper beam and the end cap.

  In the under-run protector according to the present invention, the depressed portion which becomes the starting point of deformation when impacted may be formed along the longitudinal direction of the bumper beam in a portion other than the thick portion of the bumper beam.

  In the underrun protector according to the present invention, the thick portion is formed along the longitudinal direction of the bumper beam, and the thick portion has a plurality of mounting screw holes so as not to penetrate from the outer surface to the inner surface of the bumper beam. At least one of the mounting stay on the vehicle body frame, the reflecting plate and the step plate may be attached to the outer surface of the bumper beam by a bolt that is formed and screwed into the mounting screw hole.

According to the underrun protector of the present invention, the following effects can be exhibited.
(1) When the bumper beam receives an impact, in addition to the shock absorption due to the rigidity of the bumper beam when it is deformed, the repulsive force of the air inside the bumper beam compressed by the decrease of the internal volume of the bumper beam accompanying the deformation Also, since the impact can be absorbed, it is possible to promote thinning and weight reduction of the bumper beam while securing the same impact absorbing performance as the conventional one.
(2) Since the end cap for sealing the opening at both ends of the bumper beam has a convex fitting portion inserted into the opening, both ends of the bumper beam are less likely to be deformed when an impact is received, and the end Air leakage from the gap between the cap and the opening is suppressed to maintain sealing performance, and the repulsive force of the compressed air can be effectively used for shock absorption.
(3) The cap screw holes for attaching the end cap to the openings at both ends of the bumper beam are formed in the thick portions formed at the four corners of the bumper beam so as not to penetrate from the openings to the inner surface of the bumper beam Fastening rigidity can be secured, air leakage from the cap screw hole does not occur, and the repulsive force of compressed air can be effectively used for shock absorption.

It is a disassembled fractured perspective view of the under run protector concerning one embodiment of the present invention. It is a sectional side view of the under run protector concerning the above-mentioned embodiment. (A) is a disassembled front view of the edge part of the said underrun protector, (b) is a bb line arrow directional view of (a). It is a top view which shows the state which the said underrun protector received impact, and was deformed. It is a sectional side view which shows a mode that the said underrun protector receives impact, and is deformed, and (a) (b) (c) (d) is a sectional side view which shows the deformation process of a bumper beam. It is an explanatory view showing load bearing capacity of bumper beam before modification shown in Drawing 5 (a), (a) is a perspective view of bumper beam before modification, (b) shows load bearing R1 of bumper beam before modification. It is a table. It is an explanatory view showing load bearing R2 of a bumper beam which changes over Drawing 5 (b)-Drawing 5 (d), (a) is a perspective view of a bumper beam showing before and after modification, (b) is with bumper beam modification. It is a table | surface which shows the absorption load (load resistance R2) by the internal air compressed, and (c) is explanatory drawing for calculating absorption load R2. It is an explanatory view showing load bearing R3 of a bumper beam after modification shown in Drawing 5 (d), (a) is a perspective view of a bumper beam after modification, (b) shows load bearing R 3 after bumper beam modification. It is a table. It is a fractured perspective view of the bumper beam which shows the under run protector concerning the modification of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in the embodiment are merely examples for facilitating the understanding of the invention, and the invention is not limited unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

(Overview of Under-Run Protector According to this Embodiment)
As shown in FIG. 1, the underrun protector 1 according to the present embodiment includes a bumper beam 2 having a hollow square cross section whose both ends are opened, and thick portions 4 formed at four corners of the opening 3 of the bumper beam 2. At the opening 3 of the bumper beam 2 with the cap screw hole 5 formed so as not to penetrate the inner surface of the bumper beam 2 in the thick part 4 of the opening 3 of the bumper beam 2 and the bolt 6 screwed into the cap screw hole 5 An end cap 8 having a convex fitting portion 7 to be mounted and inserted into the opening 3 and sealing the opening 3 is provided, and when the bumper beam 2 is deformed by an impact, the inside of the bumper beam 2 is provided. The repulsive force of air compressed as the volume decreases absorbs a part of the impact load. Each component will be described below.

(Bumper beam 2)
As shown in FIGS. 1 to 3, the bumper beam 2 is formed in a hollow square cross-sectional shape having openings 3 at both ends, and is extruded from, for example, an aluminum alloy (6061-T6 or the like). The bumper beam 2 may have a shape that is gently bent after extrusion, in addition to the straight shape. The material of the extruded bumper beam 2 is not limited to the aluminum alloy, and may be steel, titanium or the like.

(Thickness 4)
As shown in FIGS. 1 and 2, thick portions 4 are formed along the longitudinal direction (extrusion direction) at the four corners of the inner surface of the bumper beam 2. A plate-like horizontal portion 9 thinner than the dimension in the height direction of the thick portion 4 is formed between the thick portions 4 spaced in the longitudinal direction of the vehicle, and the thickness separated in the vertical direction A plate-like vertical portion 10 thinner than the dimension of the thick portion 4 in the vehicle front-rear direction is formed between the thick portions 4. That is, the bumper beam 2 has thick portions 4 at four corners, horizontal portions 9 and vertical portions 10 between them, and is formed into a hollow square cross-sectional shape by extrusion.

(Cap screw hole 5)
As shown in FIG. 3 (b), cap screw holes 5 are formed so as not to penetrate the inner surface of the bumper beam 2 in the thick portions 4 of the openings 3 at both ends of the bumper beam 2 having a hollow square cross section. . After extruding the bumper beam 2, the cap screw hole 5 is vertically formed in the thick portion 4 of the end face of the opening 3 at both ends of the beam by cutting.

(End cap 8)
As shown to FIG. 1, FIG. 3 (a), the end cap 8 which seals the opening 3 is mounted | worn with the opening 3 of the both ends of the bumper beam 2 of hollow square cross-sectional shape. The end cap 8 is integrally formed of a base plate portion 11 pressed against the end face of the opening 3 and a convex fitting portion 7 inserted into the inside of the opening 3. The through hole 12 of the base plate portion 11 is integrally formed. By screwing the bolt 6 inserted into the cap screw hole 5 into the cap screw hole 5, the bolt 6 is attached in close contact with the opening 3 of the bumper beam 2.

(Fitting 7)
As shown in FIG. 1, the fitting portion 7 of the end cap 8 is formed in contact with the inner surface of the opening 3 in accordance with the inner surface of the opening 3 of the bumper beam 2. Thereby, as shown in FIG. 4, when the bumper beam 2 receives an impact force and is deformed, the inner surface of the opening 3 of the bumper beam 2 is supported by the fitting portion 7 of the end cap 8 and the deformation of the opening 3 is suppressed Thus, the compressed air in the bumper beam 2 can be prevented from leaking between the end cap 8 and the opening 3. The end cap 8 may be made of the same material as the bumper beam 2 but may be made of a different material (metal, resin, etc.).

  As shown in FIGS. 4 and 5 (a) to 5 (d), when the bumper beam 2 receives an impact force F, a position where the thick portion 4 in the input front is pressed against the thick portion 4 in the input rear It deforms to a shape that recedes to the maximum, and further deformation is suppressed. That is, the thick portion 4 also functions as a stopper that limits the amount of deformation (amount of retraction) of the bumper beam 2 that has received the impact force F. At this time, as shown in FIG. 4, the fitting portion 7 suppresses deformation of the opening 3 of the bumper beam 2 to suppress air leakage.

(Gasket 13)
As shown in FIGS. 1 and 3A, a gasket 13 for preventing air leakage is interposed between the opening 3 of the bumper beam 2 and the end cap 8. The gasket 13 is made of a material (for example, resin, rubber, etc.) softer than the bumper beam 2 and the end cap 8 and formed in a frame shape through which the fitting portion 7 of the end cap 8 is inserted. By screwing into the hole 5, it is sandwiched between the end face of the opening 3 of the bumper beam 2 and the base plate portion 11 of the end cap 8 to prevent air leakage.

  Also, instead of the gasket 13, a sealing agent (for example, a silicon-based sealing agent) may be applied to the joint surface between the opening 3 of the bumper beam 2 and the end cap 8 to prevent air leakage. In addition, when the sealing performance between the opening 3 of the bumper beam 2 and the end cap 8 can be sufficiently ensured by screwing the bolt 6 into the cap screw hole 5, even if the gasket 13 or the sealing agent is omitted. Good.

(Mounting screw hole 14, mounting stay 16, reflection plate 17, step plate 18)
As shown in FIGS. 1 and 2, a plurality of mounting screw holes 14 are formed in the thick portion 4 of the bumper beam 2 so as not to penetrate from the outer surface to the inner surface of the bumper beam 2. The mounting stay 16 to the vehicle body frame, the reflecting plate 17 and the step plate 18 are attached to the outer surface of the bumper beam 2 by the screwed-in bolt 15. The mounting screw hole 14 is formed in the thick portion 4 and does not penetrate the inner surface of the bumper beam 2 and therefore does not become a passage for air leakage.

  When the underrun protector 1 is attached to the front of the vehicle, that is, in the case of a front underrun protector, the reflecting plate 17 and the step plate 18 can be omitted.

(Deformation of bumper beam 2 due to collision)
5 (a) -5 (d) show the process of deformation of the bumper beam 2 due to a collision. When the bumper beam 2 receives the collision load F, “before deformation” shown in FIG. 5 (a), “in deformation” shown in FIG. 5 (b) and FIG. 5 (c), and “in FIG. The impact load F is received in three stages after deformation.

(Before deformation)
As shown in FIG. 5 (a), when the bumper beam 2 receives the collision load F, the load bearing capacity of the horizontal portion 9 is required until the bumper beam 2 is deformed (very short time of 1 second or less). Receive the collision load F by R1.

(During transformation)
Thereafter, as shown in FIG. 5 (b), the bumper beam 2 is generated by the reduction of the internal volume of the bumper beam 2 as the horizontal portion 9 is deformed, and the internal air of the bumper beam 2 being compressed. Receive F-R1 by air repulsion r2. Then, as shown in FIG. 5C, as the horizontal portion 9 is further deformed, the internal volume of the bumper beam 2 is further reduced, and the air repulsive force r2 'generated accordingly causes F-R1-r2 Accept. The horizontal part 9 is crushed to such a distance X that the thick parts 4 shown in FIG. 5 (a) are in contact as shown in FIG. 5 (d). Assuming that r2 is a function r2 (x) of the collapse distance x, the total air repulsive force R2 while the horizontal portion 9 collapses the distance X is R2 = ∫ r2 (x) dx (d) as shown in FIG. x: 0 → X).

(After deformation)
Thus, as shown in FIG. 5D, when the bumper beam 2 is deformed to the state where the thick portions 4 are in contact with each other, the bumper beam 2 receives F-R1-R2 by the load resistance R3 of the thick portion 4. . In addition, after the bumper beam 2 receives the collision load F, the deformation from FIG. 5A to FIG. 5D is an extremely short time of 1 second or less.

  Hereinafter, when bumper beam 2 receives collision load F, resistance R1 before modification of bumper beam 2, resistance R2 during modification, and resistance R3 after modification are explained.

(Resistance R1 before deformation)
As shown in FIG. 6, when the bumper beam 2 receives the collision load F (400 kN), the resistance R1 of the bumper beam 2 before the bumper beam 2 is deformed corresponds to the load resistance of the horizontal portion 9. The length L of the pressure tester that applies collision load F to bumper beam 2 is 200 mm, the thickness T1 of horizontal part 9 is 2 mm, the material of bumper beam 2 is aluminum alloy 6061-T6, and the tensile strength is 310 N / mm ^ 2 Assuming that the proof stress is 275 N / mm 2, the load resistance R 1 of the horizontal portion 9 is L × T 1 × 275 = 110 kN, and 220 kN in the upper and lower horizontal portions 9. The collision load F (400 kN) is received with a resistance R1 of 220 kN. The load resistance R1 (220 kN) of the horizontal portion is set to be higher than the legal load resistance (100 kN) of the underrun protector and lower than the collision load (400 kN). The thickness T3 of the vertical portion 10 is 3 mm thicker than the thickness T1 of the horizontal portion 9.

(Resistance R2 during deformation)
As shown in FIG. 7, when the internal air is compressed by the deformation of the bumper beam 2, an air repulsive force is generated, which can be considered as a drag R2 during the deformation. The length L of the pressure tester that applies the collision load F to the bumper beam 2 is 200 mm, the pressure receiving surface height h1 is 107 mm, the height H of the bumper beam is 155 mm, the thickness T2 of the thick part is 24 mm, and the amount of deformation X Assuming that it is 46 mm, the internal pressure of the bumper beam before deformation is 101325 N / mm ^ 2 (standard atmosphere), and when the volume is halved, the internal pressure is doubled to 202650 N / mm ^ 2 (Boil's law). The air repulsion force A is about 2.2 kN, and the air repulsion force B after deformation is about 4.3 kN.

  Therefore, the total repulsive force (air absorption load) R2 during the deformation X (46 mm) deformation is R2 = ∫ r2 dx (x: 0 → X), that is, as described with reference to FIG. The area of the trapezoid in FIG. 7C is obtained, and R2 = (pre-deformation repulsion A + reformation post-deformation repulsion B) × deformation amount X 量 2 becomes 150 kN. Here, A = r2 (0) and B = r2 (X). The load of 180 kN obtained by subtracting the resistance R1 from the collision load F is received by the resistance R2 of 150 kN.

  The air absorption load R2 (150 kN) due to air repulsion is equivalent to about 38% of the load to be absorbed (400 kN) when the collision load F is 400 kN, and the remaining about 62% of the impact load Will be absorbed by mechanical deformation. Therefore, the impact absorption force by mechanical deformation of the bumper beam 2 can be reduced to about 62% as compared with the conventional type that does not use air repulsion, and the mechanical strength of the bumper beam 2 is reduced by that amount to reduce weight Can promote

  As shown in FIG. 5 (b) and FIG. 5 (c), the horizontal portion 9 is buckled along the surface direction because it is expanded to the outside of the bumper beam 2 by the pressure of air compressed in the bumper beam. It does not crush and bend and deform outward properly. Thus, the horizontal portions 9 expand outward of the bumper beam 2 so that the thick portions 4 come in face-to-face contact as shown in FIG. 5D, and the deformation amount X is properly defined.

  The horizontal portion 9 does not break up to the 90-degree bending shown in FIG. 5 (b), but may be considered to break at the stage of FIG. 5 (c) and FIG. 5 (d). Thus, if the horizontal portion 9 breaks in the middle of deformation, air leakage occurs, but the time from the 90 degree bending of the horizontal portion 9 in FIG. 5B to the facing contact of the thick portion in FIG. There is no problem because air leakage occurs after the repulsive force R2 of the compressed air acts, because the range of the crack is considered to be limited. In FIG. 7A, the thickness D of the bumper beam 2 is 110 mm.

(Resistance R3 after deformation)
As shown in FIG. 8, after the thick portions 4 are deformed to be in surface contact with each other, a resistance R 3 of the bumper beam 2 corresponds to a load resistance of the thick portions 4. The length L of the pressure tester which applies the collision load F to the bumper beam 2 is 200 mm, the thickness T2 of the thick part is 24 mm, the material of the bumper beam is 6061-T6 aluminum alloy, and the tensile strength is 310 N / mm ^ 2, Assuming that the yield strength is 275 N / mm ^ 2, the load resistance R3 of the thick portion is L × T2 × 275 = 1320 kN, and is 2640 kN at the upper and lower thick portions 4. The drag force R1 is subtracted from the collision load F with a drag force R3 of 2640 kN, and the load 30 kN obtained by subtracting the drag force R2 is received.

(Action / effect)
As shown in FIG. 1, according to the underrun protector 1 according to the present embodiment, since the openings 3 at both ends of the bumper beam 2 having a hollow square cross section are sealed by the end cap 8, as shown in FIG. When the bumper beam 2 receives an impact load F, as shown in FIG. 5 (b) to FIG. 5 (d), in addition to the impact absorbing force R1 due to the rigidity when the bumper beam 2 is deformed. The impact can also be absorbed by the repulsive force R2 (R2 = ∫r2dx) of the air inside the bumper beam which is compressed by the accompanying reduction of the internal volume of the bumper beam. Therefore, it is possible to promote thinning and weight reduction of the bumper beam 2 while securing the same shock absorbing performance as the conventional one.

  As shown in FIG. 5D, the thick portions 4 contact each other to function as a stopper, so that the amount of displacement (amount of retraction) of the bumper beam 2 is limited in the event of a collision. Therefore, the horizontal portion 9 is deformed by setting the distance X between the thick portions 4 to a prescribed displacement (100 mm) or less (in the present embodiment, 46 mm) that allows the reverse run of the underrun protector 1 to collide. Can meet the laws and regulations properly. In addition, since the thick portion 4 functions as a stopper that limits the deformation of the bumper beam 2, the internal volume of the bumper beam 2 that is hollow and whose both ends are sealed by the end cap 8 is prevented from becoming excessively small. Can suppress bursting of the bumper beam 2 due to excessive compression, and compressed air repulsion can be properly used as shock absorption.

  As shown in FIGS. 1 and 3, since the end cap 8 for sealing the opening 3 at both ends of the bumper beam 2 has a convex fitting portion 7 inserted into the opening 3, as shown in FIG. When the bumper beam 2 receives an impact, both ends of the bumper beam 2 are less likely to be deformed. As a result, air leakage from the gap between the end cap 8 and the opening 3 is suppressed, sealing is maintained, and the repulsive force of the compressed air can be effectively used for shock absorption. Further, as shown in FIG. 1, air leak can be further suppressed by interposing the gasket 13 or the sealing agent between the opening 3 of the bumper beam 2 and the end cap 8.

  As shown in FIGS. 1 and 3, the cap screw holes 5 for attaching the end cap 8 to the openings 3 at both ends of the bumper beam 2 do not penetrate the thick part 4 of the opening 3 of the bumper beam 2 to the inner surface of the bumper beam 2 Since it is formed in such a manner, the screwed length of the bolt 6 of the end cap 8 to which compressed air pressure is applied can be gained to secure the fastening rigidity, air leakage does not occur from the cap screw hole 5, and repulsion of compressed air Force can be used effectively for shock absorption.

  As shown in FIGS. 1 and 2, the mounting stay 16 for mounting the bumper beam 2 to the vehicle body frame is a mounting formed on the thick portion 4 of the bumper beam 2 so as not to penetrate from the outer surface to the inner surface of the bumper beam 2 The bumper beam 2 is mounted by means of a bolt 15 screwed into the screw hole 14. Therefore, air leakage does not occur from the mounting screw hole 14, and the repulsive force of the compressed air can be effectively used for shock absorption. Similarly, the reflection plate 17 and the step plate 18 attached to the bumper beam 2 are attached to the bumper beam 2 by bolts 15 screwed into attachment screw holes 14 formed in the thick portion 4. Therefore, no air leaks from these mounting screw holes 14. Further, since the impact force applied to the mounting stay 16 is alleviated by the air repulsive force R2 generated when the bumper beam 2 receives the impact load F, the mounting stay 16 also has the same impact absorbing performance as the conventional one. To promote thickness reduction and weight reduction.

(Modification)
FIG. 9 shows an underrun protector 1a according to a modification of the present invention. The underrun protector 1a basically has the same configuration as the underrun protector 1 according to the previous embodiment, and when impact is applied to a portion (horizontal portion 9) of the bumper beam 2 other than the thick portion 4 This embodiment differs from the first embodiment in that the depression 19 that is the starting point of deformation is formed (for example, extrusion) along the longitudinal direction of the bumper beam 2.

  According to the underrun protector 1a, the recess 19 is the starting point of the bending deformation, and the deformation of the horizontal portion 9 is guided to the outside. When the bumper beam 2 is made of aluminum alloy (e.g., 6061-T6), as shown in FIG. 5C, when the horizontal portion 9 is bent and deformed, the tip of the bent portion of the bending is bent as a characteristic of the aluminum alloy. Since a sharp angle is formed and breakage occurs in the middle of deformation to easily reduce the sealing performance, compressive stress on the inside of the bent portion of the bent horizontal portion 9 is relieved by the depression 19 shown in FIG. Be suppressed.

  While the preferred embodiments of the present invention have been described with reference to the accompanying drawings, it is a matter of course that the present invention is not limited to the above-described embodiments, and various modifications in the scope described in the claims. It goes without saying that the modifications also fall within the technical scope of the present invention. For example, the present invention is not limited to the rear underrun protector, but can be applied to the front underrun protector.

  Further, in the above-described embodiment (FIG. 6, FIG. 7, FIG. 8), the case where the pressure test element with a length of 200 mm is made to collide with the bumper beam 2 is taken as an example. Although the shock absorption capacity was analyzed, at the time of an actual collision, the bumper beam 2 was crushed within the range of the vehicle collision width (usually longer than 200 mm), and the internal air was compressed according to the collapsed volume to generate a repulsive force R2. , Will absorb shock. For example, the air repulsive force R2 of the range 400 mm of the vehicle collision width is 150 × 2 = 300 kN.

  The present invention is applicable to an underrun protector mounted on the front and rear of a vehicle such as a truck.

Reference Signs List 1 underrun protector 2 bumper beam 3 opening 4 thick portion 5 cap screw hole 6 bolt 7 fitting portion 8 end cap 13 gasket 14 mounting screw hole 15 bolt 16 mounting stay 17 reflecting plate 18 step 19 hollow portion F impact load R2 air Repulsive force

Claims (4)

Bumper beam of hollow square section, open at both ends,
Thick portions formed at the four corners of the opening of the bumper beam,
A cap screw hole formed in the thick portion so as not to penetrate the inner surface of the bumper beam from the opening;
An end cap attached to the opening of the bumper beam with a bolt screwed into the cap screw hole and having a convex fitting portion inserted into the opening, and sealing the opening;
An under-run protector, which absorbs a part of an impact load by a repulsive force of air compressed as the internal volume of the bumper beam decreases, when the bumper beam is deformed by an impact.   The underrun protector according to claim 1, wherein a gasket or a sealing agent is interposed between the opening of the bumper beam and the end cap.   The hollow portion which becomes the starting point of deformation when receiving an impact is formed in a portion other than the thick portion of the bumper beam along the longitudinal direction of the bumper beam. Underrun protector as described in. The thick portion is formed along the longitudinal direction of the bumper beam,
A plurality of mounting screw holes are formed in the thick portion so as not to penetrate from the outer surface to the inner surface of the bumper beam,
At least one of a mounting stay on a vehicle body frame, a reflecting plate and a step plate is mounted on the outer surface of the bumper beam by a bolt screwed into the mounting screw hole. The under-run protector as described in any one of to 3.

Images