JP2011051581A - Crash box and automobile body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crash box in which stable bellows-like plastic buckling deformation can be produced continuously by suppressing the occurrence of bending deformation on the entire part even against an impact load applied thereto in the direction diagonal to the axial direction. <P>SOLUTION: This crash box 3-1 is formed of a metal cylindrical body which comprises corner parts 4, 5 and corner parts 6, 7 respectively arranged in pairs so as to face each other and has a rectangular cross sectional shape. The angle formed by the corner parts 4, 5 is 90-150&deg; inclusive, and the angle formed by the corner parts 6, 7 is 30-90&deg; inclusive. One groove 12, 13 which extends in the longitudinal direction and project inward is formed on each of two sides across at least one corner part 4. The circumferential length of the cylindrical body in cross section at one end is smaller than the circumferential length of the cylindrical body in cross section at the other end. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a crash box and an automobile body, and more specifically, even if an impact load due to a collision from an oblique direction as well as a direction parallel to the axial direction is input, it is continuously stable and bellows-like. The present invention relates to a crash box having an excellent shock absorption characteristic against oblique collision, that is, a high shock absorption energy absorption amount, and an automobile body including the crash box.

  A vehicle body of an automobile generally has a monocoque structure in which strength members made of a cylindrical body such as a front side member, a side sill, and a rear side member are arranged in a front-rear direction at important points of the vehicle body. And in the case of a collision accident, the safety | security of a passenger | crew is aimed at by absorbing the impact energy loaded by a collision using these intensity | strength members as an impact-absorbing member.

  In recent years, a crash box is used as one of the shock absorbing members. For example, the crash box is composed of a cylindrical body having a closed cross-sectional shape generally having an overall length of about 80 to 300 mm, and supports the bumper reinforcement while the front end members of the left and right front side members and the left and right rear side members are It is detachably attached to the rear end. Usually, two crash boxes are arranged in the front-rear direction of the vehicle body, one for each bumper reinforcement.

  Crash boxes are impacted by impacts input to the bumper reinforcement at the time of a collision, giving priority to the front side members and rear side members that make up the body shell, and plastic buckling deformation and collapsing. This prevents damage to the body shell and reduces repair costs during light collisions, and effectively absorbs impact energy together with side members to protect the occupant.

  Crash boxes that are cylindrical bodies are, for example, welded to two components, which are half-finished products formed by pressing thin steel plates, hydroformed to hollow pipes, and further to aluminum alloy materials It is manufactured into a predetermined shape by performing hot extrusion or cold extrusion.

  Many proposals have been made so far in order to improve the shock absorption characteristics of the crash box. For example, Patent Document 1 discloses an invention related to a crash box composed of a cylindrical body having a cross-shaped cross section having four branches of the same shape intersecting at right angles, and Patent Document 2 discloses an equiangular angle. An invention relating to a bumper beam including a crash box made of a hollow body constituted by a cross section having four arms arranged is disclosed.

  The present inventors disclosed a patented invention related to a crash box composed of a cylindrical body provided with a groove extending in a longitudinal direction on an outer wall excluding a ridge line portion according to Patent Document 3. This crash box has significantly improved shock absorption performance compared to the crash box disclosed in Patent Documents 1 and 2, and from the front side member and rear side member due to the impact load applied in the axial direction. As a priority, impact energy can be absorbed very efficiently by plastic buckling deformation and crushing in a bellows-like shape in substantially the entire axial direction.

EP0885681A1 Special table 2003-203272 gazette WO2005 / 010398

  In an actual automobile crash, the impact load due to the collision is continuously input in the axial direction of the crash box from the beginning to the beginning of the bellows-like plastic buckling deformation of the crash box. This is rather rare, and the input is often made obliquely with respect to the axial direction of the crash box.

FIG. 10 is an explanatory diagram schematically showing a so-called offset collision situation. Moreover, FIG. 11 is explanatory drawing which shows typically the input direction of the impact load to a crash box.
As indicated by arrows in FIG. 10, in the case of an offset collision, an impact load is input in an oblique direction with respect to the longitudinal direction of the vehicle body 1. Also, in the case of a vehicle-to-vehicle collision accident, an impact load is input in an oblique direction with respect to the vehicle height direction due to a difference in bumper installation height of each vehicle. That is, as shown in FIG. 11, an impact load is input to the crash box 2 arranged so as to be directed in the front-rear direction of the vehicle body 1 from an oblique direction with respect to the vehicle width direction and / or the vehicle height direction. There are many cases.

  On the other hand, the crash box disclosed in Patent Document 3 certainly generates plastic buckling deformation in a bellows shape stably over almost the entire area in the axial direction against an impact load applied in the axial direction. However, if an impact load is input in an oblique direction with respect to the axial direction, a bending moment is generated in the cylindrical body, and this bending moment causes a point in the middle of the bellows-like plastic buckling deformation. In this case, the entire cylinder is easily bent and deformed. When such bending deformation occurs, it becomes difficult to perform plastic buckling deformation in the shape of a bellows thereafter, and thus the impact energy absorption capacity decreases accordingly.

The present invention includes a pair of corner portions disposed opposite to each other, and another pair of corner portions disposed so as to intersect at an angle of 80 ° to 100 ° with respect to a line connecting the pair of corner portions. And having a quadrangular basic cross-sectional shape, preferably a quadrangular basic cross-sectional shape having no quadrangular basic cross-sectional shape, and one axial direction of the cylindrical body. A crash box in which an impact load is input from one end to the other end, and an angle (α) formed by a pair of corners is 90 ° or more and 150 ° or less and the other pair of corners The angle (β) formed is not less than 30 ° and not more than 90 °, and is provided on each of two sides sandwiching at least one of the pair of corner portions, extending in the longitudinal direction and projecting toward the inside 1 or A plurality of grooves, preferably one or more grooves extending in the longitudinal direction and projecting toward the inside at a position excluding the pair of corner portions and the other pair of corner portions, and having one end portion The cylinder according to the present invention is characterized in that the cross-sectional circumference of the cylinder on the side is smaller than the cross-section circumference of the cylinder on the other end side.
In the present invention, the line connecting the pair of corner portions and the line connecting the other pair of corner portions preferably intersect at an angle of 85 ° to 95 °, and more preferably approximately orthogonal.

  According to the present invention, since the cross-sectional circumferential length of the cylindrical body on the one end side that is the collision end side is smaller than the cross-sectional circumferential length of the cylindrical body on the other end side that is the anti-collision end side, When the impact force acts on the cylindrical body, the cylindrical body is surely crushed from the collision end side. That is, according to the present invention, not only when an impact load is input in a direction parallel to the axial direction of the crash box, but also when an impact load due to a collision from an oblique direction with respect to the axial direction is input. In this case, the crushing of the cylinder progresses from one end where the impact load is input toward the other end in the axial direction of the cylinder, and the cylinder is effectively buckled and deformed in a bellows shape. It is possible to absorb impact energy.

  The cross-sectional shape of the crash box according to the present invention is substantially symmetric with respect to a line passing through a pair of corner portions, and / or substantially symmetric with respect to a line passing through another pair of corner portions. It is desirable that

  In the crash box according to the present invention, a difference (α) between an angle (α) formed by a pair of corner portions and an angle (β) formed by another pair of corner portions from one end portion toward the other end portion. It is desirable that -β) increase. One end where the rigidity of the crash box in the vicinity of the side member against the bending in the vertical direction is the collision end side by arranging the other pair of corner portions in the vertical direction on the other end side of the cylindrical body It is higher than the part side. Thereby, since the bending deformation of the up-down direction which arises in a cylinder during crushing is suppressed, the bending force transmitted to a side member is suppressed. Furthermore, the cross-sectional shape of the side member can be made to have a shape with high rigidity against bending in the vertical direction, similarly to the other end side, which is the anti-collision end side of the crash box, via the engine mount bracket. The rigidity with respect to the transmitted vertical vibration of the engine is increased, and the performance against the vibration and noise of the vehicle body is improved.

  In the crash box according to the present invention, a difference (α) between an angle (α) formed by a pair of corner portions and an angle (β) formed by another pair of corner portions from one end portion toward the other end portion. -Β) may decrease. Thereby, non-uniformity in the circumferential direction of the cross section of the load propagated from the crash box to the side member is suppressed, and the side member is prevented from bending and deforming at an early stage. In addition, by arranging the line connecting the pair of corners in the horizontal direction, even if the height of the bumper reinforcement in the vertical direction cannot be secured sufficiently, the bumper reinforcement can be reliably supported, Even when a lateral load such as an oblique collision is applied to the cylindrical body, a stable buckling behavior is exhibited and the load can be reliably transmitted to the side member.

  In the crash box according to the present invention, the difference between the angle (α) formed by the pair of corner portions and the angle (β) formed by the other pair of corner portions from one end portion to the other end portion. (Α−β) may be constant.

In these crash boxes according to the present invention, the angle (α) formed by the pair of corner portions is preferably larger than the angle (β) formed by the other pair of corner portions.
In these crash boxes according to the present invention, the thickness t (mm), the length W (mm) of the side, the number N of grooves, and the opening widths of the N grooves on all the sides in the cross-sectional shape. It is desirable that the average value Wc (mm) satisfies the relationship of the following formula (1), and in this case, it is more desirable to satisfy the relationship of the following formula (1 ′).

5 <(W−N × Wc) / (N + 1) / t <50 (1)
5 <(W−N × Wc) / (N + 1) / t <30 (1 ′)
In these crash boxes according to the present invention, the grooves are preferably provided on all four sides.

In these crash boxes according to the present invention, the plate thickness t (mm) and the side length W (mm) in each of a pair of sides where no groove is provided satisfy the relationship of the following formula (2). It is desirable to do.
5 <(W / t) <50 (2)

  In these crash boxes according to the present invention, it is preferable that a region including at least one corner portion is provided with a notch portion formed by being cut out in a planar shape, and the thickness t (mm) of the notch portion. ) And the length W ′ (mm) more preferably satisfy the relationship of the following formula (3), and in this case, it is more preferable to satisfy the relationship of the following formula (3 ′). In the case of forming the notch, the side length W (mm) in the above formulas (1), (1 ′), and (2) is the length after being shortened by forming the notch. It means the length of the side.

5 <(W ′ / t) <50 (3)
5 <(W ′ / t) <30 (3 ′)

  In this case, the cylindrical body is joined by overlapping the edges of one component member or by overlapping the edges of each of the plurality of component members divided along the axial direction. It is desirable that the cut-out portion is an overlap joint portion of one constituent member or an overlap joint portion of a plurality of constituent members.

In these crash boxes according to the present invention, it is desirable that the radius of curvature R of all corner portions is larger than the radius of curvature Rc of any of the plurality of corner portions constituting the groove.
In these crash boxes according to the present invention, it is desirable that the cross-sectional circumferential length of the cylindrical body monotonously increases from one end to the other end.

  From another viewpoint, the present invention is a crash box characterized in that the above-described crash box according to the present invention is arranged in a pair or two-pair symmetry with respect to the vehicle width center in the width direction of the front part or the rear part of the vehicle body. It is a car body provided with.

  In the automobile body according to the present invention, it is desirable that the crash box be arranged so that the direction in which the line connecting the pair of corner portions is oriented is substantially the vertical direction or the substantially horizontal direction.

  Further, in the automobile body according to the present invention, the region including one corner portion of the other pair of corner portions has a notch portion formed by being cut out in a planar shape, and the crash box. Is preferably arranged so that the side on which the notch is formed is located outside the vehicle body.

  According to the automobile body including the crash box and the crash box according to the present invention, it is possible to suppress the occurrence of bending deformation as a whole, even with respect to an impact load applied in an oblique direction with respect to the axial direction. Since continuous and stable bellows-like plastic buckling deformation can be generated more reliably, it is possible to ensure excellent shock absorption characteristics, that is, high shock absorption energy absorption amount even against oblique collision.

  As a result, damage to the body shell can be suppressed to reduce the repair cost during a light collision, and impact energy can be effectively absorbed to improve the safety of the passenger.

It is explanatory drawing which shows the basic cross-sectional shape of the crash box which concerns on this invention. FIG. 2A to FIG. 2D are explanatory views showing various cross-sectional shape examples of the crash box according to the present invention. It is explanatory drawing which shows a motor vehicle body provided with the crash box which concerns on this invention. It is explanatory drawing which shows the crash box which concerns on this invention. It is explanatory drawing which shows the crash box which concerns on this invention. It is explanatory drawing which shows the crash box which concerns on this invention. It is explanatory drawing which shows the example of arrangement | positioning of the crash box which concerns on this invention in a motor vehicle body. It is explanatory drawing which shows the example of arrangement | positioning of the crash box which concerns on this invention in a motor vehicle body. It is explanatory drawing which shows analysis conditions. It is explanatory drawing which shows typically the condition of what is called an offset collision. It is explanatory drawing which shows typically the input direction of the impact load to a crash box.

[Embodiment 1]
Hereinafter, a form for carrying out a crash box concerning the present invention and a car body provided with a crash box is explained, referring to an accompanying drawing. In the following description, an example in which a line connecting a pair of corner portions and a line connecting another pair of corner portions are approximately orthogonal to each other is taken.

  However, the present invention is not limited to this embodiment, and a line connecting a pair of corner portions and a line connecting another pair of corner portions may intersect at 80 ° or more and 100 ° or less. This is because if the crossing angle is less than 80 ° or more than 100 °, the asymmetry of the cross-sectional shape increases, and the crushing becomes unstable. The intersecting angle is desirably 85 ° to 95 °, and more desirably substantially orthogonal.

First, the principle of the crash box according to the present invention will be briefly described.
The polygonal cross-section which is the cross-sectional shape of the crash box which is a cylinder is configured by an angle forming a ridge line part in the cylinder and a side which is a plane part between the ridge line parts in the cylinder. When a load is applied in the axial direction of the cylindrical body and the load acts on this cross section, the ridge line portion and the plane portion undergo out-of-plane deformation (deformation toward the outside of the closed cross section).

  At this time, the ridge line portion having high rigidity generates out-of-plane deformation smaller than that of the flat surface portion having relatively low rigidity with respect to the ridge line, and causes compressive strain. Thereafter, as the applied load increases, the amount of out-of-plane deformation also increases in the ridge line portion, eventually the ridge line portion buckles and the ridge line portion breaks, and plastic buckling deformation occurs. This crush box absorbs impact energy by repeating these series of deformations several times, and by plastic buckling deformation in a bellows shape in the axial direction and crushing.

  This series of deformation behavior changes depending on the direction of the input load. For example, when a load in the oblique direction with respect to the axial direction of the crash box is input, the amount of out-of-plane deformation of the ridge line portion is increased and the compressive strain is larger than when the load is input in the axial direction. Get smaller.

  Further, when the inputted oblique load is increased, the compressive strain generated in the ridge line portion is reduced as much as possible, a large out-of-plane deformation is generated, the ridge line portion is bent with a large curvature radius, and the entire crash box is bent. In particular, when the load input from an oblique direction acting on the flat surface portion having low rigidity is increased, the crash box is easily bent.

  For this reason, in order to suppress the bending of the entire crash box and improve the shock absorption performance against the impact load applied in the oblique direction with respect to the axial direction, the cross section of the crash box is based on the following viewpoints. It is effective to determine the shape.

That is, in order to be able to suppress bending deformation with respect to load input from an oblique direction,
(I) Increasing the degree of load of the oblique load in the ridge line portion having high rigidity, that is, having a cross-sectional shape in which the ridge line portion is arranged with respect to the input direction of the oblique load, and

(II) It is important that the ridge portion has a cross-sectional shape that reduces out-of-plane deformation caused by a load input from an oblique direction and increases compressive strain.

  Further, when an impact load is input in the axial direction of the cylindrical body constituting the crash box, the cylindrical body undergoes a plurality of plastic buckling deformations, and the impact absorption energy is determined by the load history generated at that time. In other words, the amount of impact energy absorbed is determined by the number of plastic buckling deformations that occur continuously.

  First, when an impact load is input to the cylinder, the plane portion constituting the cross section of the cylinder undergoes out-of-plane deformation, and the ridge line portion causes compressive strain. After that, as the input impact load increases, the out-of-plane deformation at the plane portion and the compressive strain at the ridge line portion both increase, and eventually the out-of-plane deformation at the ridge line portion occurs. Buckling occurs n times (n is a natural number of 1 or more) at the ridge line portion.

  And the buckling wrinkle produced | generated by the buckling deformation which arose in the ridgeline part is expanded to a plane part, and a buckling wrinkle produces | generates in a plane part. Thereafter, the buckling wrinkles generated in this plane portion are overlapped, and the process proceeds to the next buckling deformation (n + 1) occurring in another part in the axial direction.

  The interval from the n-th buckling occurrence to the (n + 1) -th buckling occurrence, that is, the buckling wavelength, is affected by the size of the wrinkles generated by the buckling of the ridge portion of the deformation as described above. In addition, the size of the wrinkles is governed by out-of-plane deformation that occurs in the flat portion. Therefore, in order to improve the impact energy absorption performance by the plastic buckling behavior with a short buckling wavelength, it is effective to reduce the out-of-plane deformation that occurs in the plane portion.

That is, in order to obtain a high impact energy absorption performance while suppressing bending deformation, in order to cause continuous plastic buckling deformation with a short buckling wavelength,
(III) It is important to shorten the length of the plane portion to control out-of-plane deformation, and (IV) to provide a desired short plane portion length by providing a recess having a ridge line in the plane portion. It is.

Furthermore, not only when an impact load is input in a direction parallel to the axial direction of the crash box, but also when an impact load due to a collision from an oblique direction is input, the side where the impact load is input In order for the crushing to proceed reliably from one end of the tube toward the other end in the axial direction of the cylindrical body, and finally to buckle and deform in a bellows shape to effectively absorb impact energy ,
(V) In the cylinder, it is important to make the cross-sectional circumference of the cylinder on the one end side to which the impact load is input smaller than the cross-sectional circumference of the cylinder on the other end side. .

The present invention is based on these principles I to V.
Next, on the premise of these principles I to V, the crash box according to the present invention will be described.

  FIG. 1 is an explanatory view showing a basic cross-sectional shape of a crash box 3 according to the present invention. 2 (a) to 2 (d) are explanatory views showing various cross-sectional shape examples of the crash boxes 3-1 to 3-4 according to the present invention.

  As shown in FIG. 1, the crash box 3 of the present invention is arranged substantially orthogonal to a pair of corner portions 4, 5 arranged opposite to each other and a line L connecting the pair of corner portions 4, 5. And a pair of corner portions 6 and 7 and a metal cylinder 38 having a rectangular basic cross-sectional shape defined by the corner portions 4 to 7 and having no flange on the outside. .

  In order to stably generate the continuous plastic buckling deformation, it is required to continuously overlap the buckling wrinkles generated by the buckling deformation. In the case of a metal cylinder having a cross-sectional shape having a flange on the outer side, it is necessary to overlap the wrinkle in a direction different from that of the flat portion when the buckling wrinkle is also superimposed on the flange, and the deformation resistance at that time is increased. . In other words, a metal cylinder having a cross-sectional shape having a flange on the outside cannot easily be buckled and wrinkled. For the above reasons, it is desirable that the metal cylinder does not have a flange on the outer side in the cross-sectional shape because it can stably exhibit plastic buckling deformation.

Therefore, the crash box 3 of the present invention is configured by a metal cylinder 38 having a cross-sectional shape having a rectangular basic cross-sectional shape that does not have a flange on the outside and is defined by the corner portions 4 to 7. . Examples of the metal include ordinary steel and high-tensile steel, but are not limited thereto, and may be appropriately selected according to the specifications required for the crash box 3.
In the above description, the case where the cylindrical body 38 has no flange on the outside has been taken as an example. However, the present invention is not limited to this case, and the case where the cylindrical body 38 has a flange on the outside is also possible. Applied.

  In addition, the “basic cross-sectional shape” in the present invention means a quadrangular cross-sectional shape that forms an outline excluding a groove portion that protrudes toward the inside in the cross-section of the cylindrical body 38, and is basically shown in FIG. As shown in (a), it means a quadrilateral 4-6-5-7 defined by the corners 4, 6, 5, and 7. However, as shown in FIG. Or when notches 24 to 27 are formed as shown in FIGS. 2 (b) to 2 (d), which will be described later, four intersections of the four sides of the quadrangle forming the outline of the cylinder This means a virtual rectangle 4-6-5-7 defined by 4, 6, 5, and 7.

In this way, the crash box 3 has an outer shape having a cross-sectional shape in the first direction (substantially left-right direction in FIG. 1) or in the second direction (substantially up-down direction in FIG. 1) substantially orthogonal to the first direction. The basic cross-sectional shape of a quadrangle in which the corner portions 4 to 7 that are ridge line portions having high rigidity are arranged.
In the crash box 3, as described above, the line connecting the pair of corner portions 4, 5 and the line connecting the other pair of corner portions 6, 7 are substantially orthogonal as a preferred embodiment of the present invention, but 80 It suffices to intersect at an angle of not less than 100 ° and not more than 100 °, and it is desirable to intersect at an angle of not less than 85 ° and not more than 95 °.

  It is desirable that the basic cross-sectional shape of the crash box 3 is substantially symmetric with respect to a virtual line L that passes through the pair of corner portions 4 and 5. Furthermore, it is desirable that the shape is substantially symmetric with respect to a line passing through the other pair of corner portions 6 and 7. This is because the higher the symmetry, the higher the performance against oblique loads from various input directions. However, it is not necessary to be completely symmetrical in a geometric sense, and the degree of symmetry may be appropriately determined according to the specifications required for the crash box 3.

  In the case of an offset collision, an oblique load in the first direction (for example, the vehicle width direction) or a direction substantially orthogonal to the first direction (for example, the vertical direction) is input, so that a bending moment is generated in the crash box 3. In order for the crash box 3 to stably generate plastic buckling deformation even when the load is input from such an oblique direction, the entire bending deformation (bending) caused by the bending moment is suppressed, and the input It is important that the generated impact load causes continuous plastic buckling deformation with a short buckling wavelength similar to the case where the impact load is input in the axial direction of the cylindrical body 38. This is because when the entire cylindrical body 38 is bent and deformed, the buckling wavelength is long. Therefore, corner portions 6 and 7 having high rigidity are arranged at positions corresponding to the outer edges where the load acts. For this reason, in the crash box 3, as shown in FIG. 2A, the corner portions 6 and 7 are arranged on a straight line passing through the center of the cross section.

In the crash box 3, the angle α (the angles θ ₁ and θ ₂ in FIG. 1) formed by the pair of corner portions 4 and 5 is set to 90 ° to 150 °, and the other pair of corner portions 6. , 7 is set to an angle β (angles θ ₃ and θ ₄ in FIG. 1) of 30 ° or more and 90 ° or less. The reason for this will be explained.

The rigidity of the corner portions 4 to 7 as the ridge line portion is determined by the arc length existing in the ridge line portion. When the corner portions 4 to 7 are set with a specific curvature radius, the arc length is set to the corner portions 4 to 7. Varies depending on the interior angle. Therefore, in order to cause plastic buckling deformation by the impact load without causing the entire bending of the crash box 3 with respect to the bending moment generated by the impact load input from an oblique direction, the pair of corner portions 4, An internal angle α (θ ₁ , θ ₂ ) formed by 5 is set to 90 ° or more and 150 ° or less.

When the angle α (θ ₁ , θ ₂ ) exceeds 150 °, the radius of curvature of the corner R portion is determined within a range that takes into account the manufacturing and design space of the crash box (1.5). In the case where the arc length of the corner portions 6 and 7 is too short, the desired rigidity cannot be ensured, and the targeted plastic buckling deformation cannot be generated.

Further, the internal angle β (θ ₃ , θ ₄ ) formed by the other pair of corner portions 6 and 7 is interlocked with the internal angle α (θ ₁ , θ ₂ ) formed by the pair of corner portions 4 and 5. The angles θ ₁ and θ ₂ are set to be 30 ° or more and 90 ° or less as the angle is set to 90 ° or more and 150 ° or less.
Preferably, the angle α is not less than 90 ° and not more than 120 °, and the angle β is not less than 60 ° and not more than 90 °. As a result, the rigidity of the ridge line at the angle α and the rigidity of the ridge line at the angle β are maintained in an appropriate balance, and a more stable buckling deformation can be obtained as a whole member.

When higher bending rigidity is required for the other pair of corner portions 6 and 7 than the pair of corner portions 4 and 5, the angles θ ₁ and θ ₂ formed by the pair of corner portions 4 and 5 are different from each other. It is desirable that the angle is greater than the angles θ ₃ and θ ₄ formed by the pair of corner portions 6 and 7.

  The crash box 3 has a shape capable of increasing the degree of load of the oblique load at the corner portions 4 to 7 that are ridge portions having high rigidity, that is, the corner portions 4 to 7 are arranged in the input direction of the oblique load. The cross-sectional shape is as follows. Moreover, by setting it as the cross-sectional shape which provides the corner parts 4-7, while being able to reduce the out-of-plane deformation | transformation which arises with respect to the load input from the diagonal direction, the compressive strain with respect to the corner parts 4-7 is raised. be able to.

  Further, the crash box 3 includes two pairs of sides (8, 9) and (10, 11) that are arranged substantially symmetrically with respect to a virtual straight line L passing through the pair of corner portions 4 and 5. Are extended in the longitudinal direction and protrude toward the inside at positions excluding the pair of corner portions 4 and 5 and the other pair of corner portions 6 and 7, respectively. 1 or a plurality of grooves 12 and 13 (one case is shown in FIG. 1).

  These grooves 12 and 13 have a plate thickness t (mm), a length W (mm) of the sides 8 to 11, the number N of the grooves 12 and 13, and the N grooves 12 in the sides 8 and 9, respectively. 13, the average value Wc (mm) of the opening widths satisfies the relationship of the following equation (1), preferably the relationship of the following equation (1 ′).

5 <(W−N × Wc) / (N + 1) / t <50 (1)
5 <(W−N × Wc) / (N + 1) / t <30 (1 ′)
As a result, the crash box 3 can be plastic buckled and deformed in a bellows shape with a short buckling wavelength, and high impact absorption energy absorption performance can be obtained. The reason for this will be explained.

  From the occurrence of buckling to the next occurrence of buckling, the crash box 3 causes continuous plastic buckling (progressive buckling), and in order to increase the amount of shock absorption energy absorption determined by the load history caused by the deformation. It is effective to suppress the load fluctuation of the material, that is, to shorten the buckling wavelength. This buckling wavelength is closely related to the out-of-plane deformation (displacement) caused by the impact load in the cross section of the cylindrical body 38 constituting the crash box 3, and if the amount of this out-of-plane deformation is large, the buckling wavelength becomes long. When the out-of-plane deformation is small, the buckling wavelength is shortened. Therefore, in order to reduce the out-of-plane deformation occurring in the cross section of the cylinder 38 constituting the crash box 3, the width of the sides 8 to 11 constituting the cross section, that is, the distance between the adjacent corner portions 4 to 7 is set. Just make it smaller.

Specifically, the distance W between the corner portions 4 to 7 is set to be less than 50 times the plate thickness t of the cylindrical body 38. That is, in this crush box 3, the plate thickness t (mm) and the side length W (mm) at each of the sides 10 and 11 forming a pair with no grooves 12 and 13 are expressed by the following formula (2). Satisfy the relationship.
5 <(W / t) <50 (2)

  On the other hand, as shown in FIG. 1, by providing grooves 12 and 13 on the sides 8 and 9 where the distance W between the corner portions 4 to 7 is 50 times or more the plate thickness t, the plane portion 8 and 9 are divided, and the sides 8 and 9 excluding the grooves 12 and 13 satisfy the relationship of the above expression (2).

  Even if the distance W between the corner portions 4 to 7 is less than 50 times the plate thickness, the flat portions 8 and 9 are further divided by providing the flat portions 8 and 9 with the grooves 12 and 13. You may do it.

  It is desirable to provide the grooves 8 and 9 at positions that do not include the corner portions 4 to 7 that become the starting point of plastic buckling deformation due to the suppression of the overall bending deformation when an oblique load is applied.

  As described above, the crush box 3 is provided with the grooves 12 and 13 in the flat portions 8 and 9 in order to obtain a short buckling wavelength when the width W of the flat portions 8 and 9 is large. A new ridge line portion is formed by the grooves 12 and 13, and the widths of the plane portions 8 and 9 are controlled within a range in which a short buckling wavelength can be obtained.

  Here, in order to surely obtain the above-described effect, the plate thickness t (mm), the length W (mm) of the sides 8 to 11 and the number N of the grooves 12 and 13 in all the sides 8 to 11, It is desirable that the average value Wc (mm) of the opening widths of the N grooves 12 and 13 satisfies the relationship of the formula (1): 5 <(W−N × Wc) / (N + 1) / t <50. (2): It is desirable to satisfy the relationship of 5 <(W−N × Wc) / (N + 1) / t <30.

Incidentally, when the depth _{d c} of the groove 12, 13 is too shallow, since the weakened effect of cutting edges 8 and 9 described above, the depth _{d c} of the groove 12, 13 is preferably set to 10mm greater.
In the crash box 3, it is desirable that the curvature radius R of all the corner portions 4 to 7 is larger than any curvature radius Rc of the corner portions 14 to 21 constituting the grooves 12 and 13. The reason for this will be explained.

  The cross-sectional secondary moment of the thin-walled ring is governed by the diameter and the wall thickness, and the cross-sectional secondary moment increases as the diameter increases, and the section modulus that affects the bending strength also increases as the diameter increases. That is, in order to suppress bending deformation against a bending moment generated when a load is applied to the crash box 3 from an oblique direction, the corner portions 4 to 4 that are positioned on the outer surface of the cross section and support the input load. It is effective to increase the second moment of section 7. Moreover, when the curvature radius of the corner | angular parts 14-21 which comprise the groove | channels 12 and 13 is enlarged, the deformation resistance in the groove | channels 12 and 13 will increase too much, and it will become difficult to produce the plastic buckling deformation in this part.

  For the reasons described above, in the present invention, the radius of curvature R of all the corner portions 4 to 7 that dominate the overall bending strength of the crash box 3 is set to the radius of curvature Rc of the corner portions 14 to 21 constituting the grooves 12 and 13. It is desirable to make it larger.

Thus, the crash boxes 3 of the present embodiment, the first direction or the second direction is arranged a corner portion 4-7, the inner angle theta ₁ through? ₄ which form the corner portion 4-7 optimal At least one of the two pairs of sides (8, 9) and (10, 11) arranged approximately symmetrically with a virtual straight line L passing through the pair of corners 4, 5 One or a plurality of grooves that extend in the longitudinal direction to the positions excluding the corner portions 4, 6, and 7 and that protrude toward the inside and satisfy the formula (1) are formed on each of the pair of sides 8 and 9 By providing, the bending strength when an oblique load is input is improved and plastic buckling deformation is generated by this impact load.

  For this reason, the crash box 3 can suppress the occurrence of bending deformation as a whole even with an impact load applied in an oblique direction with respect to the axial direction, and can be plastically buckled and deformed in a bellows shape. it can.

  2 (a) to 2 (d) show various crash boxes 3-1 to 3-4 having cross-sectional shapes obtained by modifying the basic cross-sectional shape of the crash box 3 according to the present invention shown in FIG. It is explanatory drawing which shows. Hereinafter, with respect to the crash boxes 3-1 to 3-4, portions that are different from the crash box 3 will be described, and common portions will be denoted by the same reference numerals, and redundant description will be omitted.

  The crash box 3-1 shown in FIG. 2A is the same as the crash box 3 shown in FIG. 1 except that the grooves 22 and 23 are provided not only on the paired sides 8 and 9 but also on the paired sides 10 and 11. Grooves 12, 13, 22, 23 are provided on all four sides 8-11.

  Compared with the crash box 3, the crash box 3-1 is more symmetrical with respect to the cross-sectional shape, so that the performance against oblique loads from various input directions is improved accordingly.

  The crash box 3-2 shown in FIG. 2B includes notches 24 and 25 formed in the crash box 3 by cutting the region including the other pair of corner portions 6 and 7 into a flat shape. Is. The width W 'of the notches 24 and 25 is more than 5 times less than 50 times, preferably less than 30 times the plate thickness t of the cylindrical body forming the crash box 3-2.

  When the notches 24 and 25 are provided, the side length W (mm) in the above formulas (1), (1 ′), and (2) means that the notches 24 and 25 are formed. Means the length of the side after being shortened.

  The crush box 3-3 shown in FIG. 2 (c) includes notches 26 and 27 formed by cutting a region including the pair of corner portions 4 and 5 into a flat shape in the crush box 3-2. Is. The width W 'of the notches 26 and 27 is more than 5 times less than 50 times, preferably less than 30 times the plate thickness t of the cylindrical body forming the crash box 3-3.

  Even when the notches 26 and 27 are provided, the length W (mm) of the side in the above formulas (1), (1 ′), and (2) forms the notches 26 and 27. It means the length of the side after shortening by doing.

A crash box 3-3 shown in FIG. 2 (d) is formed by providing notches 24 to 27 in the crash box 3-2 and is a new one that most controls the overall bending strength of the crash box 3-3. By making the curvature radii ρ _b of the vertices 28a to 28h larger than the curvature radii Rc of the corner portions 14 to 21 constituting the grooves 12 and 13, plastic buckling deformation is surely generated.

  Although the plastic buckling deformation is further stabilized by providing the notches 24 to 27, the ratio (W '/ t) of the width (length) W' to the plate thickness t of these notches 24 to 27 is set. If the ratio is less than 5 times, the effect is small. On the other hand, if the ratio (W ′ / t) is 50 times or more, the buckling wavelength becomes long, and the impact energy absorption effect decreases.

  In the crash boxes 3 to 3-4 described above, it is desirable that the crash box 3-3-4 is mounted on the vehicle body so that the direction in which the line connecting the pair of corner portions 4 and 5 is directed is substantially vertical or horizontal.

  Moreover, in the crash boxes 3-2 to 3-4 shown in FIG. 2B to FIG. 2D, the cylindrical body is joined by overlapping the edges of one component member, or in the axial direction. It is constituted by overlapping and joining the respective edge portions of the plurality of constituent members divided along, and a part of the above-described notches 24 to 27, for example, the notches 24 and 25 or the notches 26, It is desirable that the reference numeral 27 denotes a superposed joint portion of one constituent member or a superposed joint portion of a plurality of constituent members.

  In particular, when the notches 24 and 25 are overlapped joints that are edges of one constituent member, or overlapped joints between a plurality of constituent members, an impact load due to a collision from an oblique direction is applied. As a result, the bending rigidity of the cylindrical body 38 is improved, and it becomes possible to suppress the occurrence of bending deformation of the entire cylindrical body 38 in the middle of the bellows-like plastic buckling deformation. Furthermore, when the joining of the overlap joint is continuous joining such as adhesion using a structural adhesive or continuous welding such as laser welding, for example, rather than intermittent joining such as spot welding, for example. This is desirable because the bending rigidity of the cylindrical body 38 can be further increased.

  These crash boxes 3 to 3-4 are attached to the vehicle body so that the direction in which the line connecting the pair of corner portions 4 and 5 is directed to the substantially vertical direction or the substantially horizontal direction. It is possible to suppress the occurrence of bending deformation as a whole even for impact loads that are input from an oblique direction with respect to the direction or vehicle height direction, thereby enabling continuous and stable bellows-like plastic buckling deformation to occur. Therefore, it is possible to ensure excellent shock absorption characteristics, that is, a high shock absorption energy absorption amount even for an oblique collision.

  Furthermore, the crash box according to the present invention is characterized in that the cross-sectional circumferential length of the cylindrical body on one end side to which an impact load is input is smaller than the cross-sectional circumferential length of the cylindrical body on the other end side. Therefore, this point will be described. In the following description, the crush box 3-1 having the cross-sectional shape shown in FIG. 2A is taken as an example, but the crush box 3 having the cross-sectional shape shown in FIG. The same holds true for the other crash boxes 3-2 to 3-4 having the cross-sectional shape shown.

  FIG. 3 is an explanatory view showing an automobile body 30 provided with the crash box 3-1 according to the present invention, and the middle diagram of FIG. 3 is a crash box 3-mounted in the crash box mounting area A in the left diagram of FIG. FIG. 3 is an explanatory diagram showing 1 extracted and enlarged, and the right diagram in FIG.

  The crash box 3-1 is made of a metal cylinder 38 having a closed cross-sectional shape generally having an overall length of about 80 to 300 mm, and is joined to the rear surface of the front bumper reinforcement 31 by appropriate means such as welding. Crash box mounting area that is set immediately in front of the front ends of the left and right front side members 33 that are fixed to the left and right hood ridges 32 that form part of the engine compartment while supporting the front bumper reinforcement 31. A is detachably attached to A via a mounting plate 35 shown in the right view of FIG. 3 (omitted in the left and middle views of FIG. 3). As usual, two crash boxes 3-1 are arranged in the vehicle width direction one by one with respect to the front bumper reinforcement in the front-rear direction of the vehicle body.

  3 denotes an engine mount bracket that is mounted on the upper surface of the front side member 33 and supports the engine unit, and 37 is mounted on the lower surfaces of the left and right front side members 33. It is a lower cross member for joining these two.

In the crash box 3-1, an angle α (θ ₁ , a pair of corner portions 4, 5 is formed from one end 39 to the other end 40 to which an impact load is directly input from the front bumper reinforcement 31. The difference (α−β) between θ ₂ ) and the angle β (θ ₃ , θ ₄ ) formed by the other pair of corner portions 6 and 7 increases, and the cylinder 38 on the one end portion 39 side increases. (The “cross-sectional circumferential length” in this specification means the circumferential length in the transverse section of the cylinder) smaller than the sectional circumference of the cylinder 39 on the other end 40 side. As described above, the dimensions of each part of the cylindrical body 38 are set.

  In the example shown in FIG. 3, the cross-sectional circumferential length of the cylindrical body 38 monotonously increases from the one end portion 39 side toward the other end portion 40 side, but the present invention is limited to this. For example, it may increase or decrease in the middle between one end 39 and the other end 40, and this does not impair the effects of the present invention. In short, it is only necessary that the cross-sectional circumference at one end 39 is smaller than the cross-sectional circumference at the other end 40.

  Here, the cross-sectional peripheral length ratio defined as (the cross-sectional peripheral length of one end portion 39) / (the cross-sectional peripheral length of the other end portion 40) is preferably 0.6 or more and 0.9 or less. When the cross-section circumference ratio is less than 0.6, the load at the initial stage of crushing after the start of the collision becomes excessively small, and the energy absorption performance at the initial stage of the collapse is lowered, while the cross-section circumference ratio is more than 0.9. The stabilization of buckling due to the suppression of bending deformation at the time of an oblique collision, which is the effect of the present invention, is small, and bending is likely to occur.

  Further, as shown in the right diagram of FIG. 3, in this example, the increase in the cross-sectional circumference of the cylinder 38 is vertically symmetric as viewed from the side of the vehicle body, but the increase in the cross-section circumference is limited to this form. Instead, the degree of increase in the cross-sectional circumference in the region above the horizontal plane passing through the center of the cylinder 38 may be different from the degree of increase in the cross-sectional circumference in this lower region.

In the crash box 3-1 shown in FIG. 3, the cylindrical body 38 has a substantially square outline on the side of one end 39, and the angle α≈angle β≈90 °, whereas the other end On the side of the portion 40, the angle α> the angle β, and the angle α formed by the pair of corner portions 4, 5 and the other pair of corner portions 6 as it goes from the one end portion 39 to the other end portion 40. , 7 and the difference (α−β) from the angle β (θ ₃ , θ ₄ ) increases.

  The crush box 3-1 shown in FIG. 3 has a cross-sectional circumferential length of the cylindrical body 38 on the one end 39 side which is smaller than a cross-sectional circumferential length of the cylindrical body 38 on the other end 40 side. When an impact load is input to the portion 39 by the front bumper reinforcement 31, the crushing surely proceeds from the one end portion 39 to the other end portion 40, and finally the cylindrical body 38 buckles in a bellows shape. It becomes possible to deform and effectively absorb the impact energy.

  Further, when the other pair of corner portions 6 and 7 are arranged on the other end portion 40 side of the cylindrical body 38 so as to be separated from each other in the vertical direction, the vicinity of the other end portion 40 side with respect to the bending in the vertical direction. The rigidity is increased compared to the collision end side, thereby suppressing the vertical bending deformation that occurs in the crash box during crushing. As a result, the bending force propagating to the side member is suppressed. Further, it is possible to reduce the vibration and noise of the vehicle body caused by the vibration in the vertical direction of the engine transmitted through the engine mount bracket 36 disposed on the upper surface of the front side member 33.

  In this way, the crash box 3-1 has priority over the front side member 33 that forms the body shell by the impact load input to the bumper reinforcement 31 even in the case of an oblique collision as well as a frontal collision. In addition, the impact energy is absorbed by plastic buckling deformation and crushing in a bellows shape, thereby preventing damage to the body shell and reducing the repair cost at the time of a light collision, and the impact energy together with the front side member 33. Can be absorbed effectively to protect the occupant.

[Embodiment 2]
Next, a second embodiment will be described. In the following description of each embodiment, parts that are different from the already described embodiments will be described, and the same parts as those already described are denoted by the same reference numerals in the drawings, thereby overlapping. Description to be omitted is omitted as appropriate.

  FIG. 4 is an explanatory diagram showing the crash box 3-1-1 according to the present invention, and FIG. 5 is an explanatory diagram showing the crash box 3-1-2 according to the present invention. 4 and 5 are both B arrow views corresponding to the right view of FIG. 3 described above.

Both the crash box 3-1-1 shown in FIG. 4 and the crash box 3-1-2 shown in FIG. 5 have one end 39 to the other end 40 to which an impact load is input by the front bumper reinforcement 31. The difference between the angle α (θ ₁ , θ ₂ ) formed by the pair of corner portions 4 and 5 and the angle β (θ ₃ , θ ₄ ) formed by the other pair of corner portions 6 and 7 (α− β) is decreased, and the cylindrical body 38 has a cross-sectional circumferential length of the cylindrical body 38 on the one end portion 39 side that is smaller than a sectional circumferential length of the cylindrical body 39 on the other end portion 40 side. The dimensions of each part are set.

  In the example shown in FIGS. 4 and 5, the circumferential length of the cross section of the cylindrical body 38 is monotonically increased from the one end portion 39 side toward the other end portion 40 side. For example, it may be increased or decreased in the middle between the one end portion 39 and the other end portion 40, and this does not impair the effects of the present invention.

  4 and 5, the increase in the cross-sectional circumference of the cylinder 38 is vertically symmetric when viewed from the side of the vehicle body, but the increase in the cross-section circumference is not limited to this form. The degree of increase in the cross-sectional circumference in the region above the horizontal plane passing through the center of the body 38 may be different from the degree of increase in the cross-sectional circumference in this lower region.

  4 and the crash box 3-1-2 shown in FIG. 5 are both cylinders 38 on the side of the other end 40 connected to the front end of the front side member 33. Since the cross-sectional shape of the crush box is substantially square, when the deformation of the crush box 3-1-1, 3-1-2 is finished, a substantially equal load is applied to the entire circumference of the front side member 33. When the front side member 33 is crushed and deformed subsequent to the end of the crushing, it is possible to suppress the front side member 33 from being bent and deformed at an early stage.

  In addition, the crash box 3-1-1 shown in FIG. 4 has a design in which the lateral cross-sectional shape of one end portion 39 is wide in the vehicle width direction, so that importance is given to a case where a lateral load such as an oblique collision acts. The bending rigidity on the side of the one end portion 39 that is effective at the time of the crash box 3-1-1 is higher in the vehicle width direction than in the vertical direction. Moreover, since the crash box 3-1-1 shown in FIG. 4 has a cross-sectional shape with a low vertical height on the one end portion 39 side, for example, the front bumper reinforcement 31 of the front bumper reinforcement 31 is requested by an exterior design request. Even when the height in the vertical direction cannot be sufficiently secured, the front bumper reinforcement 31 can be reliably supported.

  Furthermore, the crash box 3-1-1-2 shown in FIG. 4 is a cut-out formed by cutting out the area including the other pair of corner portions 6 and 7 in the crash box 3-1-1. It is provided with notches 6-3 and 7-3. The width of the notch 6-3 (that is, the distance between the apexes 6-1 and 6-2 in FIG. 4) and the width of the notch 7-3 (that is, the apexes 7-1 and 7-2 in FIG. 4). The distance between them is 5 times or more and less than 50 times, preferably less than 30 times the plate thickness t of the cylindrical body forming the crash box 3-1-1-2.

  It is desirable that the notches 6-3 and 7-3 are formed so that a region including the other pair of corners 6 and 7 is planar. Forming the notches 6-3 and 7-3 in this way is shown in the crash box 3-1 shown in FIG. 3, the crash box 3-1-2 shown in FIG. 5, and further shown in FIG. This is also effective in the crash boxes 3-1-3, 3-1-4, and 3-1-5. By forming the notches 6-3 and 7-3, the same effect as the crash box 3-2 shown in FIG. 2B can be obtained.

  On the other hand, the crash box 3-1-2 shown in FIG. 5 has a design in which one end portion 39 has a wide cross-sectional shape in the vehicle height direction, and therefore emphasizes bending force acting in the vertical direction, such as offset collisions in the vertical direction. It is effective in the case of.

[Embodiment 3]
FIG. 6 is an explanatory diagram collectively showing the crash boxes 3-1-3, 3-1-4, and 3-1-5 according to the present invention. 6 is also a B arrow view corresponding to the right view of FIG. 3 described above.
The crash boxes 3-1-3, 3-1-4, and 3-1-5 shown in FIG. 6 are all from one end 39 to the other end 40 to which an impact load is input by the front bumper reinforcement 31. The difference between the angle α (θ ₁ , θ ₂ ) formed by the pair of corner portions 4 and 5 and the angle β (θ ₃ , θ ₄ ) formed by the other pair of corner portions 6 and 7 (α− β) is constant, and the cross-sectional circumferential length of the cylindrical body 38 on the one end 39 side is smaller than the cross-sectional circumferential length of the cylindrical body 39 on the other end 40 side. The dimensions of each part are set.

  The crash box 3-1-3 is a case where the cylindrical body 38 has a cross-sectional shape close to a square at both the one end portion 39 and the other end portion 40, and the crash box 3-1-4, 3 -1-5 is a case where the cylindrical body 38 has a flat cross-sectional shape (substantially rhombus) in both the one end 39 and the other end 40.

  Since each of the crash boxes 3-1-3, 3-1-4, and 3-1-5 has a small cross-sectional circumferential length of the cylindrical body 38 on the one end 39 side that is the collision end side, Plastic deformation is surely easily generated from the tip of the portion 39. Moreover, since the cross-sectional circumferential length on the other end 40 side is large, the rigidity against bending is higher than that of the one end 39, so that the crushing progresses without applying excessive bending force to the front side member 33. can do.

  In the above description, the front crash box attached to the front side member is taken as an example. However, the present invention is not limited to the front crash box, and similarly applies to the rear crash box attached to the rear side member. Is done.

7 and 8 are explanatory diagrams showing examples of arrangement of the crash boxes 42a and 42b according to the present invention in the automobile body 41. FIG.
In this example, the crash boxes 42a and 42b according to the present invention are joined to the rear surface of the front bumper reinforcement 44 by appropriate means such as welding, and at the front end portions of the front side members 43a and 43b constituting the body shell, It is detachably mounted by appropriate means such as fastening.

As shown in this example, it is desirable to arrange the crash boxes 42a and 42b according to the present invention in a pair or two-pair symmetry with respect to the vehicle width center in the width direction of the front part or the rear part of the vehicle body.
When two pairs of the crash boxes 42a and 42b according to the present invention are arranged with respect to the vehicle width center, for example, the left front side member 43a is arranged with respect to the front side members 43a and 43b as shown in FIG. The two crash boxes 42a may be arranged in the vehicle width direction at the front end of the vehicle, and the two crash boxes 42b may be arranged in the vehicle width direction at the front end of the right front side member 43b, as shown in FIG. As described above, the two crash boxes 42a are arranged in the vehicle height direction at the tip of the left front side member 43a, and the two crash boxes 42b are arranged in the vehicle width direction at the tip of the right front side member 43b. May be.

The present invention will be specifically described with reference to examples.
Table 1 shows the shape of the crash box used in this example.

(1) Shape Inventive Examples 1 to 4 and Inventive Example 6 shown in Table 1 include notches as well as one groove on each side, as shown in the crash box 3-1-1-2 in FIG. Further, the cross-sectional circumference increases monotonously from the collision end side toward the anti-collision end side, and in the first and second invention examples, the angle difference (α−β) is monotonous from the collision end side toward the anti-collision end side. In the invention examples 3, 4, and 6, the angle difference (α−β) is constant from the collision end side to the anti-collision end side.

  Moreover, the curvature radius of the corner R part which comprises each cross section of invention example 1-4 and invention example 6 is 5 mm, and the line which connects a pair of corner parts which comprise the basic cross-sectional shape of invention example 1-4 Is perpendicular to the line connecting the other pair of corner portions, and the line connecting the pair of corner portions constituting the basic cross-sectional shape of Invention Example 6 and the line connecting the other pair of corner portions are 85 °. Cross at.

  Invention Example 5 in Table 1 is provided with one groove on each side as shown in the crash box 3-1-1 of FIG. 4, and the cross-sectional circumference increases monotonously from the collision end side toward the anti-collision end side. In addition, the angle difference (α−β) is constant from the collision end side toward the anti-collision end side, and the radius of curvature of the corner R portion constituting the cross section is 5 mm, which constitutes the basic cross-sectional shape. A line connecting a pair of corner portions and a line connecting another pair of corner portions are orthogonal to each other.

  Further, Comparative Examples 1, 2, 3, and 4 in Table 1 are Invention Example 3, Invention Example 1, Invention Example 5, respectively, except that the circumferential length of the cross section is constant from the collision end side toward the anti-collision end side. This is similar to Invention Example 6.

(2) Analysis Method FIG. 9 is an explanatory diagram showing analysis conditions.
As shown in FIG. 9, the rigid wall 46 having an inclination angle of 0 degrees and 10 degrees with respect to the end face (contact surface) 45 a of the crash box 45 of the inventive examples 1 to 6 and the comparative examples 1 to 4 is the axis of the crash box 45 An analysis was performed in which a crushing impact of 150 mm stroke was performed at a speed of 16 km / h in the direction, and the plastic buckling behavior of the crash box 45 was investigated.

  The plate thickness of the crash box 45 is 1.2 mm in all cases, the axial length of the cylindrical body constituting the crash box 45 is 200 mm, and the analysis assumes material characteristics assuming a 440 MPa class high-tensile steel plate. Furthermore, the strain rate dependence was taken into account according to the Cowper-Symmonds rule.

(3) Analysis results Table 2 summarizes the analysis results.
In Table 2, F1 is the average value of the crushing load between the rolling amount of 30 mm and 70 mm at which the initial deformation is stable, and F2 is the average value of the crushing load between the reduction amount of 120 mm and 140 mm. The load ratio f is a ratio between F1 and F2 (F1 / F2), and f ₀ and f ₁₀ represent crush load ratios with inclination angles of 0 ° and 10 °, respectively.

As shown in Table 2, when the inclination angle is 10 degrees, all of Comparative Examples 1 to 4 are bent in the latter half of the crushing stroke and become unstable buckling. , crushing load ratio _{f 10} became 0.78 or less.

On the other hand, Invention Examples 1 to 6, in the inclination angle of 10 degrees, compared with the comparative example, the bending deformation is suppressed, becomes stable buckling, the crushing load ratio f ₁₀ was significantly improved and 0.83 or more.
In particular, Invention Example 1, Invention Example 3, Invention Example 5, and Invention Example 6 in which the angles α and β of the cross section on the anti-collision end side are 120 ° and 60 °, respectively, have a very high crushing load ratio f _{10 and} are good. Met.

Further, as shown by f ₁₀ / f ₀ in Table 2, in comparison with Comparative Examples 1 and 3, in Invention Examples 1 and 3, the performance at the time of crushing at an inclination angle of 10 degrees compared to the crushing at an inclination angle of 0 degrees. The decrease is small. That is, it has been found that the crash box of the present invention significantly reduces the performance degradation against the collision load from the oblique direction.

3,3-1 to 3-4, 3-1-1 to 3-1-5, 3-1-1-2 Crash box 4 according to the present invention, 5, a pair of corner portions 6, 7, and another pair of corners Part 6-1, 6-2, 7-1, 7-2 Vertex 6-3, 7-3 Notch part 8-11 side (plane part)
12, 13, 22, 23 Grooves 14 to 21 Corners 24 to 27 Notches 28a to 28h Apex 30 Automobile body 31 Front bumper reinforcement 32 Hood ridge 33 Front side member 35 Mounting plate 36 Engine mount bracket 37 Lower cross member 38 Tube Body 39 One end 40 The other end 41 Automobile body 42a, 42b Crash box 43a, 43b Front side member 44 Front bumper reinforcement 45 Crash box 45a End surface (contact surface)
46 rigid wall

Claims (10)

A pair of corner portions disposed opposite to each other, and another pair of corner portions disposed so as to intersect at an angle of 80 ° to 100 ° with respect to a line connecting the pair of corner portions, and A crash box composed of a metal cylinder having a cross-sectional shape with a quadrangular basic cross-sectional shape, in which an impact load is input from one end of the cylinder in the axial direction to the other end. There,
The angle (α) formed by the pair of corner portions is 90 ° or more and 150 ° or less, and the angle (β) formed by the other pair of corner portions is 30 ° or more and 90 ° or less,
Having one or a plurality of grooves provided on each of two sides sandwiching at least one of the pair of corner portions and extending in the longitudinal direction and projecting toward the inside;
The crash box according to claim 1, wherein a cross-sectional circumferential length of the cylindrical body on the one end side is smaller than a cross-sectional circumferential length of the cylindrical body on the other end side.   2. The crash box according to claim 1, wherein the cross-sectional shape is substantially symmetric with respect to at least one of a line passing through the pair of corner portions and a line passing through the other pair of corner portions.   The difference (α−β) between the angle (α) formed by the pair of corner portions and the angle (β) formed by the other pair of corner portions increases from the one end portion toward the other end portion. The crash box according to claim 1 or 2.   A difference (α−β) between an angle (α) formed by the pair of corner portions and an angle (β) formed by the other pair of corner portions decreases from the one end portion toward the other end portion. The crash box according to claim 1 or 2.   The crash box according to any one of claims 1 to 4, wherein the groove is provided on all four sides.   The crash box according to any one of claims 1 to 5, further comprising a cutout portion formed by cutting a region including at least one corner portion into a flat shape.   The crash box according to any one of claims 1 to 6, wherein a cross-sectional circumferential length of the cylindrical body monotonously increases from the one end portion toward the other end portion.   The crash box according to any one of claims 1 to 7, wherein the groove is provided at a position excluding the pair of corner portions and the other pair of corner portions. A crash box characterized in that the crash box according to any one of claims 1 to 8 is arranged in a pair or two-pair symmetry with respect to a vehicle width center in a width direction of a front portion or a rear portion of a vehicle body. A car body with a box.   The automobile body including the crash box according to claim 9, wherein the crash box is disposed such that a direction in which a line connecting the pair of corner portions is oriented is substantially in a vertical direction or a substantially horizontal direction.

Images