JP5991711B2 - Bumper beam for automobile - Google Patents

Description

  The present invention relates to an automotive bumper beam made of FRP, which has a plurality of U-shaped cross sections that are continuous in the vertical direction.

  Covering a part of the front edge and a part of the rear edge of the plurality of horizontal plates overlaid at a predetermined interval in the vertical direction with the front plate and the rear plate, respectively, and extending the plurality of horizontal plates in the vertical direction A bumper beam made of FRP connected in a lattice pattern with a vertical plate is known from Japanese Patent Application Laid-Open No. 2004-151867.

Japanese Patent No. 4850349

  By the way, when continuous fibers are used as the fibers to be included in the FRP resin constituting the bumper beam, it is possible to increase the strength, but there is a problem that the formability is lowered due to the limit of expansion and contraction and bending of the continuous fibers. is there. On the other hand, when discontinuous fibers are used as the fibers to be contained in the FRP resin, the discontinuous fibers are easily adapted to an arbitrary shape and thus formability is improved, but there is a problem that strength is lowered. In order to obtain a bumper beam made of FRP with high energy absorption performance at the time of collision, it is necessary not only to increase its strength, but also to secure a shape suitable for absorbing collision energy, so that both strength and formability are compatible. Is required.

  Patent Document 1 discloses that carbon fibers, glass fibers, metal fibers, and the like can be used as fibers to be included in the resin constituting the bumper beam. Is not disclosed at all.

  This invention is made | formed in view of the above-mentioned situation, and it aims at providing the bumper beam excellent in the energy absorption performance which combined the continuous fiber FRP layer and the discontinuous fiber FRP layer.

In order to achieve the above object, according to the invention described in claim 1, a bumper beam is configured by continuously extending a plurality of U-shaped cross-sections extending in the vehicle width direction and opening outward in the front-rear direction in the vertical direction. The U-shaped cross section includes an upper wall, a lower wall, and a bottom wall formed by laminating a continuous fiber FRP layer and a discontinuous fiber FRP layer, and constitutes a front-rear direction inner wall of the bumper beam. Includes an inserted fastening collar and an outer wall in the front-rear direction of the cross member is provided with an inserted nut, and the bumper beam and the cross member are fastened by screwing a bolt and the nut passing through the fastening collar. A bumper beam for automobiles is proposed.

  According to the invention described in claim 2, in addition to the configuration of claim 1, the vertical interval between the upper wall and the lower wall of the U-shaped cross section is directed outward in the front-rear direction. A bumper beam for automobiles, which is characterized by an expansion, is proposed.

  According to the invention described in claim 3, in addition to the configuration of claim 1 or claim 2, the continuous fiber FRP includes the first continuous fiber and the second continuous fiber arranged in directions intersecting each other. A bumper beam for automobiles is proposed in which the first continuous fibers are arranged in the vehicle width direction.

  According to the invention described in claim 4, in addition to the configuration of claim 3, an automobile bumper beam is proposed in which the second continuous fibers are arranged in the front-rear direction or the vertical direction.

  According to the invention described in claim 5, in addition to the configuration of any one of claims 1 to 4, in the vicinity of the fastening collar, the front-rear inner surface of the bottom wall and the cross member A bumper beam for automobiles is proposed in which a gap is formed between the front and rear outer surfaces.

According to the invention described in claim 6, in addition to the structure of any one of claims 1 to 5 , the discontinuous fiber FRP layer is integrally formed on the inner surface in the front-rear direction of the bottom wall. A bumper beam for an automobile is proposed in which the boss portion includes a reinforcing rib that reinforces the boss portion, and the boss portion includes the inserted fastening collar .

  According to the invention described in claim 7, in addition to the configuration of any one of claims 1 to 6, the end portion in the vehicle width direction of the U-shaped cross-sectional portion is connected to the discontinuous fiber FRP. A bumper beam for automobiles is proposed, characterized in that it is closed by an end wall formed integrally with the layer.

  According to the invention described in claim 8, in addition to the configuration of any one of claims 1 to 7, the plurality of U-shaped cross-sections are provided with an upper flange provided on the upper wall; A bumper beam for automobiles is proposed, which is connected to a lower flange provided on the lower wall.

  The rear cross member 15 of the embodiment corresponds to the cross member of the present invention.

According to the structure of Claim 1, a bumper beam is comprised by making the several U-shaped cross-sectional part extended in the vehicle width direction and opened to the front-back direction outer side continue in an up-down direction. The U-shaped cross-section includes an upper wall, a lower wall, and a bottom wall formed by laminating a continuous fiber FRP layer and a discontinuous fiber FRP layer. The continuous fiber FRP layer and the discontinuous fiber FRP layer are sequentially peeled inward, and the fibers of the continuous fiber FRP layer and the discontinuous fiber FRP layer are peeled off from the resin, thereby efficiently absorbing the collision energy. be able to. Further, the plurality of U-shaped cross-sections are continuously arranged in the vertical direction, so that the amount of energy absorption can be increased while minimizing the front-rear dimension of the bumper beam. Moreover, the bottom wall constituting the front-rear inner wall of the bumper beam has an inserted fastening collar and the front-rear outer wall of the cross member has an inserted nut, and the bumper beam and the cross member are bolts that penetrate the fastening collar. Since it is fastened by screwing with the nut , not only can the U-shaped cross-section be firmly fixed to the cross member with the fastening collar, but also the collapse margin of the U-shaped cross-section can be prevented from being reduced by the fastening collar. Energy absorption effect can be enhanced.

  According to the second aspect of the present invention, since the vertical distance between the upper wall and the lower wall of the U-shaped cross section increases toward the outer side in the front-rear direction, the vertical dimension of the U-shaped cross section is increased. It is possible to receive impact loads input from different heights.

  According to the configuration of claim 3, the continuous fiber FRP layer includes the first continuous fiber and the second continuous fiber arranged in a direction intersecting each other, and the first continuous fiber is arranged in the vehicle width direction. When a collision load is input to the U-shaped cross section of the bumper beam, the strength against bending deformation in the front-rear direction of the U-shaped cross section can be increased by the first continuous fiber.

  According to the fourth aspect of the present invention, since the second continuous fibers are arranged in the front-rear direction or the up-down direction, when a collision load is input to the U-shaped cross section of the bumper beam, the U-shaped cross section is opened. This can be suppressed by the second continuous fiber.

  According to the fifth aspect of the present invention, since a gap is formed between the front and rear inner surface of the bottom wall and the front and rear outer surface of the cross member in the vicinity of the fastening collar, a stroke for collapsing the U-shaped cross section is ensured. Thus, the energy absorption effect can be enhanced.

Moreover, according to the structure of Claim 6, it was equipped with the boss | hub part integrally formed with the discontinuous fiber FRP layer in the front-back direction inner surface of the bottom wall, and the reinforcement rib which reinforces a boss | hub part, and the boss | hub part was inserted Since the fastening collar is provided , the fastening collar can be firmly fixed to the U-shaped cross section.

  According to the seventh aspect of the present invention, the vehicle width direction end of the U-shaped cross section is closed by the end wall formed integrally with the discontinuous fiber FRP layer. The opening of the part can be prevented and the energy absorption effect can be enhanced.

  According to the configuration of the eighth aspect, since the plurality of U-shaped cross sections are coupled by the upper flange provided on the upper wall and the lower flange provided on the lower wall, the plurality of U-shaped cross sections are integrated. Compared to the case of molding, not only can the mold for molding the U-shaped cross-section be downsized, but also the disturbance in the orientation direction of the fibers of the continuous fiber FRP layer of the U-shaped cross-section can be minimized. Strength can be secured.

The perspective view of the vehicle body rear part of a motor vehicle. FIG. FIG. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a view in the direction of arrows 5 in FIG. 4. Explanatory drawing of the manufacturing method of a U-shaped cross section. Action | operation explanatory drawing at the time of the input of the collision load to a bumper beam.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the present specification, the front-rear direction, the left-right direction (vehicle width direction), and the up-down direction are defined with reference to an occupant seated in the driver's seat.

  As shown in FIGS. 1 to 4, a vehicle body basically composed of CFRP (carbon fiber reinforced resin) includes a vehicle compartment rear wall 12 that stands up from a rear portion of a cabin 11 that is integrally formed in a bathtub shape. A pair of left and right suspension support members 13, 13 die-cast with an aluminum alloy are fixed to the left and right rear surfaces of the vehicle interior rear wall 12. A pair of left and right rear side frames 14, 14 extend rearward from the rear surfaces of the suspension support members 13, 13, and the rear end portions of the rear side frames 14, 14 are connected to a front wall 15a of a rear cross member 15 extending in the vehicle width direction. The rear floor panel 16 that connects the bottom surfaces of the rear side frames 14 and 14 is connected to the bottom wall 15 b of the rear cross member 15.

  A rear opening above the rear floor panel 16 is surrounded by an upper frame 17, a lower frame 18, and left and right side frames 19, 19. The lower frame 18 is overlapped with the upper wall 15c of the rear cross member 15, and the upper frame. The rear ends of a pair of left and right kick-up portions 21, 21 that rise rearward and upward from the rear ends of the pair of left and right side sills 20, 20 at both ends in the vehicle width direction, and the rear ends of the pair of left and right roof side rails 22, 22 Is connected. And on the rear wall 15d of the rear cross member 15,. A bumper beam 23 made of FRP extending in the vehicle width direction is attached.

  Next, the structure of the bumper beam 23 will be described with reference to FIGS.

  The bumper beam 23 made of FRP includes an upper wall 31a, a lower wall 31b, and a bottom wall 31c, and includes a pair of U-shaped cross-sections 31 and 31 that are opened rearward (backward in the front-rear direction). The upper flange 31d of the lower U-shaped cross section 31 and the lower flange 31e of the upper U-shaped cross section 31 are overlapped in the front-rear direction and welded together. A plurality of vertical ribs 31f that extend in the vertical direction and connect the upper wall 31a, the lower wall 31b, and the bottom wall 31c are formed inside the U-shaped cross-sectional portion 31, and both ends in the vehicle width direction are end walls. It is blocked by 31g and 31g.

  Cylindrical bosses 31h are projected forward on the front surface (the inner surface in the front-rear direction) of the bottom wall 31c at positions close to both ends in the vehicle width direction of the U-shaped cross-section 31. Are formed with eight reinforcing ribs 31i extending radially. A metal fastening collar 32 is inserted into the boss portion 31h. Two nuts 35, 35 are inserted into both ends of the rear wall 15 d of the rear cross member 15 in the vehicle width direction, and both ends of the pair of upper and lower U-shaped cross sections 31, 31 of the bumper beam 23 in the vehicle width direction. The bumper beam 23 is fastened to the rear wall 15d of the rear cross member 15 by screwing bolts 36, 36 penetrating the two fastening collars 32, 32 respectively inserted into the nuts 35, 35 into the nuts 35, 35. In this state, a predetermined gap α is formed between both ends of the bumper beam 23 in the vehicle width direction and the rear cross member 15 (see FIG. 3).

  As shown in FIG. 6B, the U-shaped cross-section 31 is configured by laminating a continuous fiber FRP layer 33 on the outer surface and a discontinuous fiber FRP layer 34 on the inner surface. The U-shaped cross section 31 is manufactured as follows. As shown in FIG. 6A, a mold 55 for press-molding the U-shaped cross section 31 includes a female mold 56 having a concave cavity 56a for molding the outer surface of the U-shaped cross section 31, and a U-shape. Are formed with a male mold 57 having a convex core 57a that molds the inner surface of the cross section 31. Grooves 57b are formed in the core 57a for molding the longitudinal ribs 31f. In a state where the mold 55 is opened, a discontinuous fiber prepreg 58 and a continuous fiber prepreg 59 are disposed on the cavity 56a of the female die 56 in a preheated state.

  The prepreg is made of carbon fiber, glass fiber, aramid fiber or other woven fabric or UD (sheet with continuous fibers aligned in one direction), or a discontinuous fiber mat, and it is semi-cured heat. It is impregnated with a curable resin (such as an epoxy resin or a polyester resin) or a thermoplastic resin (such as nylon 6 or polypropylene), and has flexibility to adapt to the shape of the mold. In the case of a thermosetting resin, when a plurality of prepregs are inserted into a mold in a laminated state and heated to, for example, about 130 ° C. while applying pressure, the thermosetting resin is cured and a fiber reinforced resin product is obtained. . In the case of a thermoplastic resin, a plurality of preheated prepregs are inserted into a mold in a laminated state, subjected to pressure molding, and then cooled to obtain a fiber reinforced resin product.

  When the male mold 57 is lowered with respect to the female mold 56, the discontinuous fiber prepreg 58 and the continuous fiber prepreg 59 are pressed by the cavity 56a of the female mold 56 and the core 57a of the male mold 57, so that the U-shaped cross-section 31 is formed. Molded. At this time, since the discontinuous fiber prepreg 58 can be easily deformed, it flows into the grooves 57b of the core 57a, and simultaneously forms the longitudinal ribs 31f of the inner surface of the U-shaped cross-section 31, and the U-shape. A thin film is laminated along the inner surface of the cross section 31. As shown in FIG. 6 (B), after cutting the excess portion of the outer periphery of the U-shaped cross section 31 taken out from the mold 55, the lower U-shaped cross section as shown in FIG. 6 (C). The upper flange 31d of 31 and the lower flange 31e of the upper U-shaped cross section 31 are overlapped in the front-rear direction and welded together to complete the bumper beam 23.

  4, the continuous fiber FRP layer 33 of the continuous fiber prepreg 59 that constitutes the outer surface of the U-shaped cross-sectional portion 31 is first and second oriented in two orthogonal directions. Reinforced with a plain weave of continuous fibers 60. Further, the discontinuous fiber FRP layer 34 of the discontinuous fiber prepreg 58 constituting the inner surface of the U-shaped cross-section 31, the longitudinal ribs 31..., The end walls 31 g and 31 g, the boss portions 31 h and 31 h, the reinforcing ribs 31 i. The discontinuous fibers 62 are reinforced with a random entanglement.

  Long fiber woven fabric or continuous fiber FRP having UD as a reinforcing material has a relatively high strength, but due to the limited amount of deformation of the woven fabric or UD, the formability is low, and thin, high ribs, etc. It is difficult to mold. On the other hand, the discontinuous fiber FRP having short fibers that are randomly intertwined as a reinforcing material has a relatively low strength, but because the fibers are easily deformed, the formability is high, and thin and high ribs are formed. Is easy. Therefore, by laminating the discontinuous fibers FRP on the outside of the continuous fibers FRP and forming the U-shaped cross section 31, the strength and formability of the U-shaped cross section 31 can be made compatible.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  According to the present embodiment, when the U-shaped cross-section 31 is press-molded with the die 55 of FIG. 6, the outer surface of the U-shaped cross-section 31 is in two directions orthogonal to each other as shown in FIG. Reinforced by the oriented first and second continuous fibers 60. The orientation direction of the first continuous fibers 60 is the vehicle width direction (that is, the main stress direction of the bumper beam 23), and the orientation direction of the second continuous fibers 61 is the direction orthogonal to the vehicle width direction (that is, the vertical direction and the front-rear direction). ). On the other hand, the inner surface of the U-shaped cross-section 31 and the vertical ribs 31f are reinforced with randomly tangled discontinuous fibers 62.

  In this way, the outer surface of the U-shaped cross-section 31 having a simple U-shaped cross section is reinforced with the first and second continuous fibers 60, 61, which are plain weave having high strength, and the plain weave is used to have a complicated shape. By reinforcing the longitudinal ribs 31f, which are difficult to reinforce with the continuous fibers, with the discontinuous fibers 62 with a high degree of freedom in molding, both the strength and formability of the bumper beam 23 can be achieved. Moreover, when the discontinuous fiber prepreg 58 and the continuous fiber prepreg 59 are arranged in the same mold 55 and the bumper beam 23 is formed in one step, they are separately formed and integrated by bonding or welding. Compared with the manufacturing cost, it can be reduced.

  When the automobile collides rearward and a collision load is input to the bumper beam 23, the pair of upper and lower U-shaped cross sections 31 and 31 of the bumper beam 23 are crushed to absorb the collision energy. At this time, as shown in FIG. 7A, when a U-shaped cross-section 31 having a simple U-shaped cross section without a rib collides with the rear surface and bends and deforms in a chain line state, tensile stress is applied to the bottom wall 31c. Acts, and compressive stress acts on the front portions of the upper wall 31a and the lower wall 31b. Therefore, by arranging the first continuous fibers 60 of the orthogonal first and second continuous fibers 60, 61 in the main stress direction (vehicle width direction), the bumper beam 23 against bending deformation at the time of rear collision. The strength of can be increased.

  When the U-shaped cross-section 31 collides rearward, as shown in FIG. 7B, the upper wall 31a and the lower wall 31b are deformed so as to open, so the direction orthogonal to the main stress direction. Tensile stress and compressive stress also act on this, but by arranging the second continuous fibers 61 in that direction, the strength of the U-shaped cross-section 31 against the opening can be increased.

  Therefore, when the U-shaped cross-section 31 collides rearward, high strength can be obtained by arranging the first and second continuous fibers 60... 61 in the vehicle width direction and the direction orthogonal thereto. However, as shown in FIG. 7C, when a collision load offset in the vertical direction is input, the U-shaped cross-section 31 is twisted and deformed, and the first and second continuous fibers 60, 61,. It is difficult to ensure rigidity against torsional deformation simply by arranging them in the orthogonal direction and reinforcing them. However, according to the present embodiment, by connecting the upper wall 31a, the lower wall 31b, and the bottom 31c of the U-shaped cross-sectional portion 31 with the vertical ribs 31f, the cost of adding continuous fibers inclined by 45 ° is reduced. The rigidity against torsional deformation can be sufficiently increased without performing bulky reinforcement.

  In addition, there is a risk that the nozzles will be clogged when trying to inject the discontinuous fibers 62 together with the resin. However, by pressing the discontinuous fiber prepreg 58 with the mold 55, the discontinuous fibers 62 having a sufficient length can be clogged. Can be used, and the strength of the U-shaped cross-section 31 can be increased.

  Thus, when a collision load of rear collision is input to the U-shaped cross-section portion 31, the continuous fiber FRP layer 33 and the discontinuous fiber FRP layer 34 are sequentially peeled from the rear portion to the front portion of the U-shaped cross-section portion 31. In addition, the fibers of the continuous fiber FRP layer 33 and the discontinuous fiber FRP layer 34 are separated from the resin, so that collision energy can be efficiently absorbed. Further, the energy absorption amount can be increased while minimizing the front-rear direction dimension of the bumper beam 23 by making the pair of U-shaped cross-sections 31, 31 continuous in the vertical direction.

  Moreover, since the space | interval of the up-down direction between the upper wall 31a and the lower wall 31b of the U-shaped cross-sectional part 31 is expanded toward back, the vertical dimension of the U-shaped cross-sectional part 31 is expanded and it inputs from different heights. The impact load can be received.

  Further, the fastening collars 32, 32 provided on the front surface of the bottom wall 31c of the U-shaped cross section 31 are fastened to the rear wall 15d of the rear cross member 15, so that the U-shaped cross section 31 is rear crossed by the fastening collars 32, 32. In addition to being firmly fixed to the member 15, it is possible to prevent the crushing margin of the U-shaped cross-sectional portion 31 (that is, the internal space of the U-shaped cross-sectional portion 31) from being reduced by the fastening collars 32, 32, and to absorb energy Can be increased. In addition, since a gap α (see FIG. 3) is formed between the front surface of the bottom wall 31c of the U-shaped cross section 31 and the rear wall 15d of the rear cross member 15 in the vicinity of the fastening collars 32, 32, the U-shaped cross section. The energy absorption effect can be enhanced by securing a stroke where the portion 31 is crushed.

  Furthermore, a boss portion 31 h formed integrally with the discontinuous fiber FRP layer 34 and reinforcing ribs 31 i for reinforcing the boss portion 31 h are provided on the front surface of the bottom wall 31 c of the U-shaped cross-section portion 31, and a fastening collar 32 is provided. Since the boss portion 31h is inserted into the boss portion 31h, the fastening collar 32 can be firmly fixed to the U-shaped cross-sectional portion 31. In addition, since the end portion in the vehicle width direction of the U-shaped cross-sectional portion 31 is closed with the end wall 31g formed integrally with the discontinuous fiber FRP layer 34, the opening of the end portion in the vehicle width direction of the U-shaped cross-sectional portion 31 is prevented. This can prevent the energy absorption effect.

  Further, since the bumper beam 23 is configured by joining the upper and lower U-shaped cross-sections 31 and 31 with the upper flange 31d and the lower flange 31e being overlapped, the pair of upper and lower U-shaped cross-sections 31 and 31 are formed. Compared to the case of forming integrally, not only can the mold 55 for forming the U-shaped cross-sections 31, 31 be downsized, but also the first and second continuous fibers 60, 61 of the U-shaped cross-sections. The strength can be ensured by minimizing the disturbance in the orientation direction.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the U-shaped cross section of the U-shaped cross section 31 includes a U-shaped cross section in which the intersection of the upper wall 31a and the lower wall 31b and the bottom wall 31c is square.

  Further, the number of U-shaped cross-sections 31 constituting the bumper beam 23 is not limited to two, and may be three or more.

  Instead of combining the plurality of U-shaped cross-sections 31 to form the bumper beam 23, the bumper beam 23 may be formed by integrally forming the plurality of U-shaped cross-sections 31.

15 Rear cross member (cross member)
23 Bumper beam 31 U-shaped cross section 31a Upper wall 31b Lower wall 31c Bottom wall 31d Upper flange 31e Lower flange 31g End wall 31h Boss part 31i Reinforcement rib 32 Fastening collar 33 Continuous fiber FRP layer 34 Discontinuous fiber FRP layer 35 Nut 36 Bolt 60 First continuous fiber 61 Second continuous fiber α Gap

Claims (8)

A plurality of U-shaped cross-sections (31) extending in the vehicle width direction and opening outward in the front-rear direction are continuously arranged in the vertical direction to form a bumper beam (23), and the U-shaped cross-section (31) is continuous. An upper wall (31a), a lower wall (31b), and a bottom wall (31c) formed by laminating a fiber FRP layer (33) and a discontinuous fiber FRP layer (34), and the bumper beam (23) in the front-rear direction The bottom wall (31c) constituting the inner wall is provided with an inserted fastening collar (32), and the outer wall in the front-rear direction of the cross member (15) is provided with an inserted nut (35), and the bumper beam (23) and the The bumper beam for automobiles , wherein the cross member (15) is fastened by screwing a bolt (36) passing through the fastening collar (32) and the nut (35) .   The vertical space between the upper wall (31a) and the lower wall (31b) of the U-shaped cross section (31) increases toward the outer side in the front-rear direction. Car bumper beam.   The continuous fiber FRP layer (33) includes a first continuous fiber (60) and a second continuous fiber (61) arranged in a direction crossing each other, and the first continuous fiber (60) is arranged in the vehicle width direction. The bumper beam for automobiles according to claim 1 or 2, characterized by being arranged.   The automobile bumper beam according to claim 3, wherein the second continuous fibers (61) are arranged in the front-rear direction or the vertical direction.   The gap (α) is formed in the vicinity of the fastening collar (32) between the front and rear inner surface of the bottom wall (31c) and the front and rear outer surface of the cross member (15). The bumper beam for automobiles according to any one of claims 1 to 4. A boss part (31h) formed integrally with the discontinuous fiber FRP layer (34) and a reinforcing rib (31i) for reinforcing the boss part (31h) are provided on the inner surface in the front-rear direction of the bottom wall (31c). The bumper beam for an automobile according to any one of claims 1 to 5 , wherein the boss portion (31h) includes the fastening collar (32) inserted therein .   The vehicle width direction end of the U-shaped cross section (31) is closed with an end wall (31g) formed integrally with the discontinuous fiber FRP layer (34). Item 7. The bumper beam for automobiles according to any one of item 6 above. The plurality of U-shaped cross-sections (31) are connected by an upper flange (31d) provided on the upper wall (31a) and a lower flange (31e) provided on the lower wall (31b). The bumper beam for automobiles according to any one of claims 1 to 7.

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