JP2024032329A - Shock absorbing parts for vehicles - Google Patents

Abstract

An object of the present invention is to provide a shock absorbing member for a vehicle that can achieve excellent energy absorption efficiency. A vehicular impact absorbing member disposed between a tip of a side member and a bumper beam includes a crash box and a pressing member 2A. The crash box has a cylindrical shape made of long fiber reinforced resin, and one end thereof is attached to the tip of the side member. The pressing member 2A is attached to an opening at the other end of the crush box opposite to one end. On the surface 2x of the pressing member 2A facing the crush box, there are formed a plurality of protrusions 20 that protrude toward the opening edge at the other end of the crush box and have ridgeline tips. Further, on the opposing surface 2x of the pressing member 2A, there is also formed an inclined surface 21 that slopes from the center O of the opposing surface 2x toward the periphery that abuts the opening edge at the other end of the crush box. [Selection diagram] Figure 2

Description

The present invention relates to a shock absorbing member for a vehicle.

A crash box is provided between the tip of the side member of the vehicle and the bumper beam. The crash box collapses before the side members when a load is applied to the bumper beam during a vehicle collision, absorbing impact energy. If the impact energy cannot be absorbed by the crash box alone, the side members are then crushed to further absorb the impact energy. Patent Document 1 below discloses a shock absorbing member that can also be used as a crash box.

The shock absorbing member disclosed in Patent Document 1 below includes a CFRP (Carbon Fiber Reinforced Plastics) cylindrical member and a pressing member provided at one end of the cylindrical member. Continuous fibers are used as carbon fiber reinforcing fibers in the CFRP cylindrical member. That is, the CFRP cylindrical member is formed of a unidirectional (UD) material in which the fiber direction is unidirectional or a cross material in which the fiber direction is crossed. The pressing member that receives the impact load splits the CFRP cylindrical member outward, thereby absorbing the impact energy.

Japanese Patent Application Publication No. 2005-233263

Since the CFRP cylindrical member of the shock absorbing member disclosed in Patent Document 1 is formed of continuous fibers, when the CFRP cylindrical member is torn, the tear immediately extends along the continuous fibers. This property is the same for both UD material and cloth material. Since the fibers intersect in the cloth material, the extension of the tear is more restricted than in the UD material, but the tear also extends along the continuous fibers, and delamination occurs all at once. For this reason, the crushing load of this CFRP cylindrical member decreases when the crack develops all at once, and the impact energy absorption efficiency does not improve sufficiently.

An object of the present invention is to provide a shock absorbing member for a vehicle that has excellent energy absorption efficiency.

The impact absorbing member for a vehicle according to the present invention can be disposed between the tip of a side member of a vehicle and a bumper beam, and includes a crash box and a pressing member. The crush box has a cylindrical shape made of long fiber reinforced resin, and one end thereof can be attached to the tip of the side member. The pressing member is attached to the opening at the other end of the crush box opposite to the one end. On the surface of the pressing member facing the crush box, there are formed a plurality of protrusions having ridgeline tips that protrude toward the opening edge of the other end of the crush box. Further, on the opposing surface of the pressing member, an inclined surface is also formed from the center of the opposing surface toward the peripheral edge that abuts the opening edge of the other end of the crush box.

According to the impact absorbing member for a vehicle according to the present invention, excellent energy absorption efficiency can be achieved.

FIG. 1 is an exploded perspective view showing a vehicle shock absorbing member according to a first embodiment. FIG. 3 is a perspective view of a pressing member of the shock absorbing member. FIG. 3 is a front view of the shock absorbing member. FIG. 3 is a side view of the shock absorbing member. 4 is a sectional view taken along the line VV in FIG. 3. FIG. It is a side view showing the crushing process (initial stage) of the above-mentioned shock absorbing member. FIG. 3 is a side view showing the crushing process (middle stage) of the shock absorbing member. It is a side view which shows the crushing process (later stage) of the said impact absorption member. FIG. 7 is a front view of a vehicle shock absorbing member according to a second embodiment. FIG. 3 is a side view of the shock absorbing member. 9 is a sectional view taken along the line XI-XI in FIG. 9. FIG.

A vehicle shock absorbing member according to an embodiment will be described with reference to the drawings. The shock absorbing member is disposed between the tip of the side member of the vehicle and the bumper beam. The shock absorbing member may be disposed between the front end of the front side member and the front bumper beam, or may be disposed between the rear end of the rear side member and the rear bumper beam.

First, a shock absorbing member according to a first embodiment will be described with reference to FIGS. 1 to 5.

As shown in FIG. 1, the shock absorbing member includes a crush box 1 and a pressing member 2A. The crash box 1 has a cylindrical shape made of long fiber reinforced resin, and one end 10 of the cylindrical shape is attached to the tip of the side member. For this reason, a metal flange 3 is attached to one end 10. The crash box 1 of this embodiment has a rectangular cross section in a cross section perpendicular to its axial direction, in accordance with the side member to which it is attached. However, the closed cross-sectional shape of the crash box 1 having a cylindrical shape is not limited to this, and may be, for example, a polygonal cross-section other than a quadrangle, a circular cross-section, or an elliptical cross-section.

The flange 3 has a rectangular shape to match the cross-sectional shape of the side member and the crush box 1. A square hole is formed in the center of the flange 3 to match the hollow part of the side member and the crash box 1. From the inner edge of this hole, an annular wall portion protrudes toward the inside of the crash box 1 and serves as an adhesive margin. The annular wall portion and one end 10 of the crash box 1 are bonded together using a structural adhesive. The flange 3 and the crush box 1 may be joined together by other methods, such as using fasteners such as bolts and nuts or rivets. Further, in this embodiment, the flange 3 is formed as a separate member from the crush box 1, but the flange 3 may be formed integrally with the crush box 1 from a long fiber reinforced resin. This flange 3 is then fixed to a flange formed at the tip of the side member using fasteners such as bolts and nuts.

As described above, the crush box 1 of this embodiment is made of long fiber reinforced resin. Although the material of the reinforcing fiber is not limited, carbon fiber is used in this embodiment. Other fibers such as glass fibers and aramid fibers may be used as the reinforcing fibers. Here, "long fibers" are used as the reinforcing fibers. The length of reinforcing fibers is generally classified into "short fibers," "long fibers," and "continuous fibers." The fiber length of the "short fibers" is less than 1 mm in the molded part. The fiber length of the "long fibers" in the molded part is about 1 mm to 50 mm. The fiber length of the "continuous fibers" is longer than that of the "long fibers", but there is no particular upper limit, and they are used for the above-mentioned UD materials and cloth materials. "Short fibers" and "long fibers" are sometimes called "discontinuous fibers" in contrast to "continuous fibers." The length of the long fibers in this embodiment is about 20 mm in the molded part.

Although the crush box 1 is formed from a long fiber reinforced resin, the manufacturing method thereof is not limited. The matrix resin may also be a thermoplastic resin or a thermosetting resin. However, in this embodiment, it is formed by SMC (Sheet Molding Compound) molding method, which has good manufacturing efficiency. In the SMC molding method, a sheet-like member called a prepreg sheet is manufactured in advance. Prepreg sheets are made by cutting reinforcing fibers (called chopped strands) into predetermined lengths, impregnating them with matrix resin, and covering both sides with a film, which is then heated under predetermined temperature conditions to thicken it and improve its handling properties. This is a sheet member. The crush box 1 is formed by press-molding a prepreg sheet using a mold.

A similar molding method is the BMC (Bulk Molding Compound) molding method. In the BMC molding method, pellets rather than sheet-like members are manufactured in advance. For example, pellets are formed by cutting a UD tape material made of continuous fibers into predetermined lengths. Long fiber pellets are sometimes called LFPs (Long Fiber Pellet). The crush box 1 can also be formed by press-molding pellets with a mold.

Further, long fiber reinforced resin using a thermoplastic resin as a matrix resin is sometimes called LFT or LFTP (Long Fiber Thermoplastics), and an injection molding method using LFT has also been put into practical use. This molding method is called the D-LFT [Direct-LFT] molding method or the LFT-D molding method. This is done by cutting reinforcing fibers into predetermined lengths and kneading them into the molten thermoplastic resin while feeding the molten thermoplastic resin with a screw inside an injection molding machine. Molten resin kneaded with reinforcing long fibers is filled into a mold from an injection molding machine and molded.

The crush box 1 made of long fiber reinforced resin can also be formed by the D-LFT molding method. In the D-LFT molding method, the long fibers tend to be oriented along the resin flow within the mold, whereas in the SMC molding method and the BMC molding method, the long fibers are oriented more randomly. Note that the crush box 1 may be molded from the long fiber reinforced resin using a molding method other than that described above. It is preferable to mold the crush box 1 at low cost using a molding method with good manufacturing efficiency.

When a vehicle collides and an impact load is applied to the vehicle, the impact load F (see FIGS. 6 to 8) is input to the crash box 1 via the bumper beam. Then, as the crash box 1 is crushed by the impact load F, the impact energy is absorbed. At this time, if the crushing load of the crash box 1 is low, the impact energy cannot be absorbed sufficiently. If the reinforcing fibers are short fibers, the reinforcing fibers are too short to sufficiently resist the impact load F, and the matrix resin is immediately destroyed, resulting in a low crushing load. If the reinforcing fibers are continuous fibers, the strength of the reinforcing fibers themselves is high, but as described above, the destruction of the matrix resin extends all at once along the continuous fibers, and the crushing load is suddenly lost on the way, resulting in a decrease in strength. For this reason, it is suitable to form the crash box 1 from a long fiber reinforced resin in terms of impact energy absorption.

In this embodiment, a pressing member 2A is provided in order to crush the crush box while maintaining a sufficiently high crushing load. Next, this pressing member 2A will be explained in detail with reference to FIGS. 2 to 5. The pressing member 2A is attached to the opening edge of the other end 11 of the crush box 1 on the opposite side from the one end 10 (attached to the tip of the side member) with a structural adhesive (in FIG. 5, the adhesive layer is not illustrated). is omitted). The surface of the pressing member 2A facing the other end 11 of the crush box 1 is referred to as the opposing surface 2x. That is, the pressing member 2A is bonded to the other end 11 of the crush box 1 with its opposing surface 2x.

On the other hand, the surface of the pressing member 2A opposite to the opposing surface 2x is referred to as an opposite surface 2y. In this embodiment, the bumper beam is bonded to the opposite surface 2y with a structural adhesive. Note that a bracket may be fixed to the opposite surface 2y with a structural adhesive or a fastener, and the bumper beam may be fixed to this bracket. Since the pressing member 2A is a member that crushes the crush box 1 made of fiber reinforced resin (FRP), it is preferably made of metal. In this embodiment, it is a cast product of iron-based metal. The pressing member 2A may be a forged product, although this increases the cost, or may be made of an aluminum alloy as long as there is no problem in crushing the crush box 1 in terms of strength.

The pressing member 2A is a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box 1. On the opposing surface 2x of the pressing member 2A that faces the crush box 1, a plurality of protrusions 20 that protrude toward the opening edge of the other end 11 of the crush box 1 and have ridgeline tips are formed. The protrusion 20 is formed on the opposing surface 2x so as to protrude toward the opening edge of the other end 11. In this embodiment, in more detail, the protrusion 20 is formed by a pair of intersecting ridge lines extending between opposite sides of the rectangle of the pressing member 2A. As a result, the four protrusions 20 are arranged at equal intervals on the periphery of the opposing surface 2x.

The protrusion 20 only needs to be provided at least on the peripheral edge facing the opening edge of the other end 11 of the crash box 1, and does not need to be formed at the center of the opposing surface 2x. That is, the pressing member 2A may be an annular member having a through hole formed in the center. Furthermore, an inclined surface 21 is also formed on the opposing surface 2x of the pressing member 2A from the center O of the opposing surface 2x toward the periphery. The sloped surfaces 21 are formed between the four protrusions 20, and each slopes so that its surface faces outward.

A valley is formed between the protrusion 20 and the inclined surface 21, and the protrusion 20 reaches the periphery of the pressing member 2A. Therefore, in order to prevent the trough from causing a decrease in the strength of the pressing member 2A, the pressing member 2A is provided at the connection between the ridgeline and the peripheral edge of the protrusion 20 so as to protrude from the peripheral edge toward the crash box 1 side. It further has a tongue 22. As shown in FIG. 3, each of the four tongues 22 protrudes so as to spread slightly outward. Note that FIG. 3 is a front view of the shock absorbing member (pressing member 2A) viewed from the opposite surface 2y side. Therefore, the contours of the protrusion 20 and the inclined surface 21 formed on the opposing surface 2x on the opposite side are indicated by dotted lines.

The outer and inner surfaces of the tongue portion 22 are three-dimensional curved surfaces. The tongue portion 22 also has the function of positioning the pressing member 2A with respect to the other end 11 of the crush box 1 during adhesion. Further, as will be described in detail later, when an impact load F is input to the opposite surface 2y via the bumper beam, the crush box 1 is crushed by the pressing member 2A. At this time, if the position of the pressing member 2A is misaligned with respect to the crush box 1, the crush box 1 will not be crushed appropriately. The tongue portion 22 also functions to position the pressing member 2A relative to the other end 11 of the crush box 1 when crushed.

Since the height of the projection 20 is constant and the opposite surface 2y is formed as a flat surface, the distance between the opposite surface 2y and the ridgeline of the projection 20 is constant. At the periphery of the opposing surface 2x, the height of the protrusion 20 is the same as or slightly lower than the height of the inclined surface 21. This is because the ridgeline of the protrusion 20 does not scrape the opening edge of the other end 11 of the crash box 1 except during a collision. However, when the pressing member 2A crushes the crush box 1 due to the impact load F, the protrusion 20 immediately comes into contact with the opening edge of the other end 11 of the crush box 1, causing the crush box 1 to split open.

On the other hand, near the center O of the opposing surface 2x, the height of the slope 21 is higher than the height of the protrusion 20 due to the slope of the slope 21. Since the vicinity of the center O of the opposing surface 2x does not directly contact the crush box 1, no problem occurs even if the inclined surface 21 is higher than the protrusion 20. As will be explained in detail next, when the crush box 1 is crushed, the outwardly directed inclined surface 21 discharges the crush box 1 torn by the protrusion 20 to the outside of the crush box 1 instead of inside the crush box 1.

Next, with reference to FIGS. 6 to 8, the process of crushing the crush box 1 by the pressing member 2A subjected to the impact load F will be described. As shown in FIG. 6, the pressing member 2A receiving the impact load F presses its protrusion 20 against the opening edge of the other end 11 of the crush box 1, thereby splitting the crush box 1 (see FIG. 6). At this time, the matrix resin is not destroyed immediately because the long fibers in the crush box 1 resist cleavage. On the other hand, since the long fibers are cut by the ridgeline of the projection 20, the cleavage progresses. Suppression of destruction of matrix resin by long fibers (both suppression of destruction at low impact load F like short fibers, and suppression of resin destruction extension along continuous fibers), and crushing due to cutting of long fibers by protrusions 20 Due to the effect of load maintenance, the crushing load is maintained sufficiently high.

The ruptured portion of the crush box 1 is guided outward by the outwardly directed inclined surface 21 and is ejected to the outside of the crush box 1 rather than to the inside. In this embodiment, since the tongue portion 22 is also formed, the cleavage portion discharged outward is guided by the tongue portion 22 in the same direction as the impact load F, rather than in the direction opposite to the impact load F. (See Figure 7). Therefore, the crushing load is maintained without changing as the cleavage progresses. Moreover, the cleavage of the crush box 1 progresses over the entire length of the crush box 1 (see FIG. 8). Therefore, a sufficient crushing stroke is also ensured.

When the torn part is discharged into the interior of the crush box 1, the torn part accumulated inside obstructs the stroke of the pressing member 2A, resulting in a short crushing stroke. In this embodiment, since the ruptured portion is discharged to the outside of the crush box 1, a sufficient crushing stroke is ensured. In this way, the crushing load can be maintained sufficiently high and a sufficient crushing stroke can be ensured, so that according to the impact absorbing member of this embodiment, impact energy can be efficiently absorbed.

Next, a shock absorbing member according to a second embodiment will be described with reference to FIGS. 9 to 11.

In the shock absorbing member of this embodiment, only the shape of the pressing member 2B is different from the pressing member 2A of the first embodiment. Therefore, below, the pressing member 2B will be mainly explained, and the other parts will be given the same reference numerals and detailed explanation thereof will be omitted. FIGS. 9 to 11 showing this embodiment are equivalent views to FIGS. 3 to 5 showing the first embodiment (illustration of the adhesive layer is omitted in FIG. 11).

The pressing member 2B is also a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box 1. Also formed on the opposing surface 2x of the pressing member 2B are a plurality of protrusions 20 that protrude toward the opening edge of the other end 11 of the crush box 1 and have ridgeline tips. The protrusion 20 is formed on the opposing surface 2x so as to protrude toward the opening edge of the other end 11. In this embodiment, in more detail, the protrusion 20 is formed by a pair of intersecting ridge lines extending along the diagonal lines of the rectangle of the pressing member 2B. It is formed by a pair of intersecting ridge lines extending between opposite sides of the rectangular shape of the pressing member 2A. Therefore, also in this embodiment, the four protrusions 20 are arranged at equal intervals on the periphery of the opposing surface 2x. However, in the first embodiment, each protrusion 20 is arranged at the center of each side of the opening edge of the other end 11 of the crash box 1, but in this embodiment, it is arranged at each corner of the opening edge of the other end 11. be done.

The protrusion 20 only needs to be provided at least on the peripheral edge facing the opening edge of the other end 11 of the crash box 1, and does not need to be formed at the center of the opposing surface 2x. Therefore, a through hole may be formed in the center of the pressing member 2B. That is, the pressing member 2B may be an annular member having a through hole formed in the center. Furthermore, an inclined surface 21 that slopes from the center O of the opposing surface 2x toward the periphery is also formed on the opposing surface 2x of the pressing member 2B. The sloped surfaces 21 are formed between the four protrusions 20, and each slopes so that its surface faces outward.

A valley is formed between the protrusion 20 and the inclined surface 21, and the protrusion 20 reaches the periphery (corner) of the pressing member 2B. For this reason, in this embodiment as well, a tongue portion 22 is formed at the connection portion (corner portion) between the ridgeline and the peripheral edge of the protrusion 20 so as to protrude from the peripheral edge toward the crash box 1 side. As shown in FIG. 9, each of the four tongue portions 22 protrudes so as to spread slightly outward. Note that FIG. 9 is a front view of the shock absorbing member (pressing member 2B) viewed from the opposite surface 2y side. Therefore, the contours of the protrusion 20 and the inclined surface 21 formed on the opposing surface 2x on the opposite side are indicated by dotted lines.

The surface of the tongue portion 22 of this embodiment is a flat surface. The reason why the tongue portion 22 has the function of positioning the pressing member 2B with respect to the crush box 1 when it is adhered, and also functions with respect to the crush box 1 when the pressing member 2B is crushed is that the tongue portion 22 has the function of positioning the pressing member 2B with respect to the crush box 1 when it is crushed. It is the same as the pressing member 2A.

The height of the protrusion 20 is constant. Similar to the first embodiment, the height of the protrusion 20 is the same as or slightly lower than the height of the inclined surface 21 at the periphery of the opposing surface 2x. However, when the pressing member 2B crushes the crush box 1 due to the impact load, the protrusion 20 immediately comes into contact with the opening edge of the other end 11 of the crush box 1, causing the crush box 1 to split open. On the other hand, near the center O of the opposing surface 2x, the height of the slope 21 is higher than the height of the protrusion 20 due to the slope of the slope 21. When the crush box 1 is crushed, the outwardly directed inclined surface 21 discharges the crush box 1 torn by the protrusion 20 to the outside of the crush box 1 instead of inside the crush box 1.

Although figures such as FIGS. 6 to 8 are not shown, the impact energy absorption member of this embodiment can maintain a sufficiently high crushing load and ensure a sufficient crushing stroke, so that impact energy can be efficiently absorbed. can do. However, in the first embodiment, the center of each wall of the crush box 1 is torn by the protrusion 20, whereas in this embodiment, the corner of the crash box 1 is torn by the protrusion 20.

According to the above embodiment, the shock absorbing member includes the crush box 1 having a cylindrical shape formed of long fiber reinforced resin, and the pressing member 2A or 2B attached to the other end 11 of the crush box 1. . On the opposing surface 2x of the pressing member 2A or 2B that faces the crush box 1, a plurality of protrusions 20 whose tips are ridgelines are formed, protruding toward the opening edge of the other end 11 of the crush box 1. There is. Further, on the opposing surface 2x of the pressing member 2A or 2B, an inclined surface 21 that slopes from the center O of the opposing surface 2x toward the periphery is also formed. Therefore, when receiving the impact load F, the crushing load can be maintained sufficiently high due to the effect of suppressing destruction of the matrix resin by the long fibers and maintaining the crushing load by cutting the long fibers by the projections 20. Further, since the cleavage portion of the crush box 1 is discharged to the outside of the crush box 1 by the inclined surface 21, a sufficient crushing stroke is ensured. In this way, by maintaining a sufficiently high crushing load and ensuring a sufficient crushing stroke, impact energy can be efficiently absorbed.

Further, according to the embodiment described above, the pressing member 2A or 2B further includes a tongue portion 22 that protrudes from the periphery toward the crash box 1 at the connection portion between the ridgeline and the periphery. The tongue portion 22 can prevent displacement of the pressing member 2A or 2B with respect to the crush box 1, and can reliably crush the crush box 1. Further, by causing the cleaved portion of the crash box 1 to be discharged by the tongue portion 22 in a direction other than the side facing the impact load, it is possible to stabilize the impact energy absorption of the impact absorbing member.

Furthermore, according to the first embodiment, the crush box 1 has a rectangular closed cross section, and the pressing member 2A is a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box 1. The protrusion 20 is formed by a pair of intersecting ridge lines extending between opposite sides of the rectangle of the pressing member 2A. In this case, the vicinity of the outer end of the protrusion 20 can be reinforced with the tongue 22 having no corners where stress concentration is low, making it easy to improve the strength and rigidity of the pressing member 2A.

On the other hand, according to the second embodiment, the crush box 1 has a rectangular closed cross section, and the pressing member 2B is a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box 1. The protrusion 20 is formed by a pair of intersecting ridge lines extending along the diagonal lines of the rectangle of the pressing member 2B. In this case, since the crush box 1 is torn at its corner, the torn part discharged outward becomes plate-shaped. For this reason, the cleavage portion of the crush box 1 is likely to curve, making it easy to be discharged to the outside.

The shock absorbing member of the present invention is not limited to the above embodiments. For example, in the above embodiment, the protrusions 20 are arranged at equal intervals around the periphery of the pressing member 2A or 2B, but the intervals do not have to be equal. Further, as long as there is no problem with the strength of the pressing member, the protrusions 20 of the first embodiment and the protrusions 20 of the second embodiment may be formed at the same time (eight protrusions are formed at equal intervals on the periphery). ).

1 Crash box 10 One end 11 (of crash box 1) Other ends 2A, 2B (of crash box 1) Pressing member 20 Projection 21 Inclined surface 22 Tongue 2x Opposing surface 2y Opposite surface F Impact load

Claims (4)

A vehicle shock absorbing member disposed between a tip of a side member of a vehicle and a bumper beam,
a crush box having a cylindrical shape formed of long fiber reinforced resin, one end of the cylindrical shape being attached to the tip of the side member;
a pressing member attached to the other end of the crash box opposite to the one end,
A plurality of protrusions whose tips are ridgelines are formed on the opposing surface of the pressing member that faces the crush box, and which protrude toward the opening edge of the other end of the crush box. A shock absorbing member for a vehicle, wherein an inclined surface is formed that slopes from the center of the surface toward a peripheral edge of the pressing member that comes into contact with the opening edge of the other end of the crash box. The vehicular shock absorbing member according to claim 1, wherein the pressing member further includes, at a connection portion between the ridgeline and the peripheral edge, a tongue protruding from the peripheral edge toward the crash box side. . The crush box has a rectangular closed cross section, and the pressing member is a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box,
The impact absorbing member for a vehicle according to claim 2, wherein the protruding portion is formed by a pair of intersecting ridge lines extending between opposite sides of the rectangular shape of the pressing member. The crush box has a rectangular closed cross section, and the pressing member is a rectangular plate-like member corresponding to the rectangular closed cross section of the crush box,
The impact absorbing member for a vehicle according to claim 2 or 3, wherein the protruding portion is formed by a pair of intersecting ridge lines extending along diagonal lines of the rectangular shape of the pressing member.

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