JPWO2015037443A1 - Auto body structure - Google Patents

Abstract

In the body structure of an automobile, the plurality of fiber reinforced resin layers of the side frame (11) having a cylindrical closed cross section include a 0 ° fiber reinforced resin layer having a fiber orientation angle of 0 ° and an inclined fiber having a fiber orientation angle other than 0 °. It is composed of a reinforced resin layer, and the number of laminated inclined fiber reinforced resin layers is the end portion (fourth portion) on the opposite side from the vicinity (first portion (13)) of the load input end portion (17) of the side frame (11). Increase toward (16)). This makes it easy to bend the 0 ° fiber reinforced resin layer of the first portion (13) in the vicinity of the load input end portion (17) to reduce the initial load, and at the opposite side of the load input end portion (17). By making it difficult for the 0 ° fiber reinforced resin layer to bend toward the fourth portion (16) at the end, the side frames (11) are sequentially crushed in the front-rear direction without being inclined with respect to the load input direction. Energy absorption can be increased.

Description

  The present invention relates to an automobile in which a side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body is configured by laminating a plurality of fiber reinforced resin layers having different fiber orientation angles with respect to the front-rear direction. Relates to the body structure.

  In a thick cylindrical body made of FRP (fiber reinforced resin), the outer layer portion has a fiber orientation angle of 90 ° (axial direction perpendicular to the fiber) more than 0 ° (axial direction) fiber, and the inner layer portion By increasing the number of fibers with a fiber orientation angle of 0 ° (axial direction) to 90 ° (axial direction), the outer layer can be prevented from peeling off when an axial load is input. The thing which enabled absorption is known by the following patent document 1.

  In addition, a shock absorbing member divided into 12 cells is provided in front of the bumper beam arranged in the vehicle width direction at the front of the vehicle body, and the front surface of the shock absorbing member is covered with a soft bumper face, thereby At the time of a collision, only a few cells are deformed with a large stroke to keep the impact small, and at the time of a collision with other vehicles, many cells are deformed with a small stroke to minimize vehicle damage. It is known from Patent Document 2 below.

Japanese Patent No. 3833718 Japanese Unexamined Patent Publication No. 2004-237810

  By the way, in the thing of the said patent document 1, since the fiber orientation angle of an outer layer part and an inner layer part is constant along the longitudinal direction (axial direction) of a cylindrical body, the load of an axial direction is applied to the one end part of a cylindrical body. When it is input, the other end side where a large bending moment acts is bent, and the cylindrical body inclines with respect to the input direction of the load, so that it collapses sequentially from one end side to the other end side. There is a possibility that efficient energy absorption cannot be performed.

  Further, in the above-mentioned Patent Document 2, since the bumper beam is composed of a member having a hollow closed cross section integrally formed of metal or fiber reinforced resin, a part of the bumper beam is damaged by a collision. However, there is a problem that the repair cost increases because it is necessary to replace the entire bumper beam. Moreover, since the shock absorbing member is composed of 12 cells having the same structure, there is a problem that the energy absorption amount cannot be adjusted according to the position where the collision load is input.

  The present invention has been made in view of the above-mentioned circumstances, and enhances the energy absorption effect of the side frame made of fiber reinforced resin having a cylindrical closed cross section, and the repair cost when the bumper beam is damaged is small, and also the collision An object of the present invention is to provide a vehicle body structure capable of easily adjusting the energy absorption amount of a bumper beam according to a position where a load is input.

  In order to achieve the above object, according to the first feature of the present invention, a side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body is provided with a fiber orientation angle of continuous fibers with respect to the front-rear direction. A plurality of fiber reinforced resin layers are laminated to form a vehicle body structure, and the plurality of fiber reinforced resin layers have a fiber orientation angle of 0 ° and a fiber orientation angle of 0 °. It is composed of an inclined fiber reinforced resin layer other than 0 °, and the number of laminated inclined fiber reinforced resin layers increases from the vicinity of the load input end of the side frame toward the opposite end. A car body structure is proposed.

  According to a second feature of the present invention, in addition to the first feature, at least one of the inclined fiber reinforced resin layers has a fiber orientation angle of 90 °. Is proposed.

  According to a third feature of the present invention, in addition to the first or second feature, the load input end portion includes a load input surface inclined obliquely with respect to the front-rear direction, and the load input A vehicle body structure is proposed in which the number of the inclined fiber reinforced resin layers is larger than that in the vicinity of the end portion.

  According to the fourth feature of the present invention, in addition to any one of the first to third features, the side frame is directed from the vicinity of the load input end to the opposite end. A vehicle body structure is proposed in which the number of laminated layers of the 0 ° fiber reinforced resin layer is increased.

  According to a fifth feature of the present invention, in addition to any one of the first to fourth features, the inclined fiber-reinforced resin layer laminated at least on the outermost side in the laminating direction and on the innermost side in the laminating direction, A vehicle body structure is proposed in which the fiber orientation angle is 45 ° or -45 °.

  According to a sixth feature of the present invention, in addition to any one of the first to fifth features, the plurality of fiber reinforced resin layers are formed by consolidating continuous fibers arranged in the same direction with a resin. A vehicle body structure characterized by comprising one type of prepreg is proposed.

  According to a seventh aspect of the present invention, in addition to the sixth aspect, the prepreg has a length in the front-rear direction that differs depending on the plurality of fiber reinforced resin layers. A structure is proposed.

  In order to achieve the above object, according to the eighth aspect of the present invention, in addition to the first aspect, a cross member made of continuous fiber reinforced resin extending in the vehicle width direction is connected to the end of the side frame. And supporting a bumper beam made of discontinuous fiber reinforced resin that absorbs energy by receiving a collision load on the outer surface in the front-rear direction of the cross member, and the bumper beam is a center disposed in the center in the vehicle width direction. A vehicle body structure for an automobile is proposed, comprising a member and a pair of end members disposed on both sides of the central member in the vehicle width direction, wherein the central member has higher compressive strength than the end member. The

  According to a ninth feature of the present invention, in addition to the eighth feature, the bumper beam includes a plurality of vertical ribs and a plurality of horizontal ribs arranged in a lattice pattern, and the vertical ribs and the horizontal ribs are arranged. A vehicle body structure for an automobile is proposed in which the lattice points where the ribs intersect are located inside the periphery of the bumper beam.

  According to a tenth feature of the present invention, in addition to the ninth feature, the density of the lattice points of the central member is higher than the density of the lattice points of the end member. A car body structure is proposed.

  According to an eleventh feature of the present invention, in addition to any one of the eighth to tenth features, the cross-sectional area of the cross member is from the vehicle width direction end portion toward the vehicle width direction center portion. A vehicle body structure characterized by an increase is proposed.

  According to a twelfth feature of the present invention, in addition to any one of the eighth to eleventh features, a nut is fixed to the cross member, and a bolt that penetrates the bumper beam is fastened to the nut. A vehicle body structure characterized by this is proposed.

  The rear side frame 11 of the embodiment corresponds to the side frame of the present invention, the rear end portion 17 of the embodiment corresponds to the load input end of the present invention, and the flange 17a of the embodiment corresponds to the load of the present invention. Corresponds to the input surface.

  According to the first aspect of the present invention, the side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body has a plurality of fiber reinforced resin layers having different fiber orientation angles with respect to the front-rear direction. It is constituted by laminating. The plurality of fiber reinforced resin layers are composed of a 0 ° fiber reinforced resin layer having a fiber orientation angle of 0 ° and a tilted fiber reinforced resin layer having a fiber orientation angle other than 0 °. Since it increases from the vicinity of the load input end of the side frame toward the opposite end, the 0 ° fiber reinforced resin layer in the vicinity of the load input end can be easily bent to reduce the initial load and load input. By making it difficult for the 0 ° fiber reinforced resin layer to bend toward the end opposite to the end, the side frame is crushed sequentially in the front-rear direction without inclining the load input direction. Can be increased. As a result, a sufficient amount of energy absorption can be ensured while reducing the weight by reducing the thickness of the side frames.

  According to the second feature of the present invention, since at least one of the inclined fiber reinforced resin layers has a fiber orientation angle of 90 °, the inclined fiber reinforced resin layer having a fiber orientation angle of 90 ° is a 0 ° fiber reinforced resin. By suppressing the out-of-plane deformation by increasing the buckling strength of the layer, it is possible to increase the energy absorption of the 0 ° fiber reinforced resin layer, and in addition, the inclined fiber reinforced resin in the process of side crushing in the front-rear direction The amount of energy absorption can be increased sequentially by increasing the number of layers.

  Further, according to the third feature of the present invention, the load input end portion has a load input surface inclined obliquely with respect to the front-rear direction, so that a bending moment acts on the load input end portion by the input of the collision load. Since the load input end portion has a larger number of inclined fiber reinforced resin layers than the vicinity of the load input end portion, the load input end portion can prevent the bending and transmit the collision load toward the opposite end portion.

  Further, according to the fourth feature of the present invention, the number of laminated layers of 0 ° fiber reinforced resin layers increases from the vicinity of the load input end portion to the opposite end portion. Even when a collision load is input and a large bending moment acts on the opposite end, the opposite end where the number of 0 ° fiber reinforced resin layers is large is prevented from bending to ensure energy absorption. Can do.

  According to the fifth aspect of the present invention, the inclined fiber reinforced resin layer laminated at least on the outermost side in the laminating direction and on the innermost side in the laminating direction has a fiber orientation angle of 45 ° or −45 °, so On the other hand, even when the collision load is input obliquely, the side frame can be prevented from bending and the amount of energy absorption can be ensured.

  According to the sixth aspect of the present invention, the plurality of fiber reinforced resin layers are composed of one type of prepreg obtained by consolidating continuous fibers aligned in the same direction with a resin, so that one type of prepreg is cut in different directions. Thus, the material cost can be reduced by forming a plurality of fiber reinforced resin layers.

  According to the seventh feature of the present invention, the prepreg has different lengths in the front-rear direction depending on the plurality of fiber reinforced resin layers. Therefore, the side frame can be increased while minimizing the number of seams of the prepreg and increasing the strength. The number of laminated fiber reinforced resin layers can be changed in each part.

  According to an eighth aspect of the present invention, a cross member made of continuous fiber reinforced resin extending in the vehicle width direction is connected to the end of a pair of left and right continuous fiber reinforced resin side frames extending in the front-rear direction. A bumper beam made of discontinuous fiber reinforced resin that absorbs energy by receiving a collision load on the outer surface in the front-rear direction of the member and compressing it is supported. The bumper beam is composed of a central member arranged at the center in the vehicle width direction and a pair of end members arranged on both sides of the central member in the vehicle width direction. Therefore, when a part of the bumper beam is damaged, the bumper beam is damaged. Repair cost can be reduced by replacing only the central member or the end member. In addition, since the central member has higher compressive strength than the end member, it is possible not only to increase the energy absorption amount of the central member, which is highly likely to receive a collision load during high speed traveling such as cruising, but also during low speed traveling such as garage storage. It is possible to reduce the weight of the end member that is highly likely to receive a load, thereby making it possible to achieve both energy absorption and weight reduction of the bumper beam. Furthermore, by dividing the bumper beam into three parts, it is possible to reduce the initial investment by reducing the size of the mold for manufacturing the bumper beam.

  According to the ninth aspect of the present invention, the bumper beam includes a plurality of vertical ribs and a plurality of horizontal ribs arranged in a lattice pattern, and the lattice point where the vertical ribs and the horizontal rib intersect is more than the periphery of the bumper beam. Because it is located on the inside, the lattice points with high rigidity are crushed by the collision load, and not only a large energy absorption effect is exhibited, but also the lattice points located on the inner side of the periphery of the bumper beam are crushed so that the vertical and horizontal ribs As a result, the energy absorption effect is further enhanced, and the protrusion height of the vertical and horizontal ribs at the periphery of the bumper beam is reduced, so that the bumper beam can be prevented from interfering with the bumper face.

  According to the tenth feature of the present invention, since the density of the lattice points of the central member is higher than the density of the lattice points of the end member, the central member is more likely to input a large collision load than the end member. This strength can be higher than the strength of the end member.

  According to the eleventh feature of the present invention, since the cross-sectional area of the cross member increases from the end in the vehicle width direction toward the center in the vehicle width direction, the center portion of the cross member to which a large collision load is input during a high-speed collision. Can be prevented.

  According to the twelfth feature of the present invention, the nut is fixed to the cross member, and the bolt that penetrates the bumper beam is fastened to the nut. Therefore, the bumper beam can be easily attached to and detached from the cross member. It is easy to change the bumper beam.

FIG. 1 is a plan view of a rear skeleton of an automobile. (First embodiment) FIG. 2 is a view in the direction of the arrow 2 in FIG. (First embodiment) FIG. 3 is a view showing a laminated state of the fiber reinforced resin layer of the rear side frame. (First embodiment) FIG. 4 is a table showing the laminated state of the fiber reinforced resin layers of the rear side frame. (First embodiment) FIG. 5 is a graph showing the relationship between the rear side frame deformation stroke and the load due to the collision load. (First embodiment) FIG. 6 is a plan view showing the skeleton of the rear part of the vehicle body. (Second Embodiment) 7 is a view in the direction of arrow 7 in FIG. (Second Embodiment) 8 is a cross-sectional view taken along line 8A-8A and a cross-sectional view taken along line 8B-8B in FIG. (Second Embodiment) FIG. 9 is a graph showing the relationship between the rear bumper stroke and the generated load due to a rear collision. (Second Embodiment) FIG. 10 is a diagram showing another embodiment of the bumper beam. (Second Embodiment)

11 Rear side frame (side frame)
17 Rear end (load input end)
17a Flange (Load input surface)
113 Cross member 114 Bumper beam 114C Central member 114L, 114R End member 114b Vertical rib 114c Horizontal rib 114d Lattice point 115 Nut 116 Bolt

  Embodiments of the present invention will be described with reference to the accompanying drawings. 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.

First embodiment

  First, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a pair of left and right rear side frames 11, 11 are arranged in the front-rear direction at the rear part of the vehicle body, and a rear bumper beam extending between the rear ends of the left and right rear side frames 11, 11 in the vehicle width direction. 12 is connected. The rear side frames 11 and 11 and the rear bumper beam 12 are made of CFRP (carbon fiber reinforced resin) in which continuous fiber layers in which carbon continuous fibers are aligned in one direction are laminated in a plurality of layers and hardened with a resin.

  As shown in FIG. 2, the rear side frame 11 is a hollow cylindrical member having a rectangular cross section, and is divided into four parts having different numbers of laminated fiber reinforced resin layers. That is, the rear side frame 11 is divided into a first portion 13, a second portion 14, a third portion 15, and a fourth portion 16 in order from the rear end side where the collision load of the rear collision is input to the front end side. A short rear end portion 17 is provided behind the first portion 13. A flat flange 17 a is provided on the rear surface of the rear end portion 17, and the flange 17 a is fixed to the front surface of the rear bumper beam 12. The flange 17a is inclined so that the outer end in the vehicle width direction is biased forward (see FIG. 1).

  As shown in FIGS. 2 to 4, the number of laminated fiber reinforced resin layers of the rear side frame 11 is such that the first portion 13 is 10 layers, the second portion 14 is 12 layers, and the third portion 15 is 14 layers. The fourth portion 16 has 18 layers, and the rear end portion 17 has 12 layers. The fiber reinforced resin layer of each part is laminated | stacked symmetrically in the surface side and the back surface side with respect to the symmetrical surface of the lamination direction center. The fiber orientation angle of the continuous fibers of the fiber reinforced resin layer is defined by an angle with respect to the longitudinal direction (front-rear direction) of the rear side frame 11, 0 ° indicates parallel to the longitudinal direction, and ± 45 ° indicates relative to the longitudinal direction. The angle is 45 ° to the left and right, and 90 ° indicates that it intersects the longitudinal direction at 90 °.

  In the fourth portion 16 laminated in 18 layers, the first layer to the ninth layer are laminated outside the symmetry plane, and the first ′ layer to the 9 ′ layer are laminated inside the symmetry plane. The first and first layers on both sides of the symmetry plane are 0 ° fiber reinforced resin layers, and the second, third and second 'and 3' layers on both sides of the symmetry plane are ± 45 ° fiber reinforced resin layers. The fourth layer and the 4 'layer on both sides of the symmetry plane are 0 ° fiber reinforced resin layers, and the fifth to seventh layers and the 5' to 7 'layers on both sides of the symmetry surface are 90 ° fiber reinforced resin layers. The 8th and 9th layers and the 8 'and 9' layers on both sides of the symmetry plane are ± 45 ° fiber reinforced resin layers.

  At the rear end of the fourth portion 16, the first layer and the first 'layer (0 ° fiber reinforced resin layer) are disconnected from the third layer and the third' layer (45 ° fiber reinforced resin layer). The third portion 15 connected to the rear of the fourth portion 16 has a 14-layer structure without the first layer, the first 'layer, the third layer, and the third' layer.

  At the rear end of the third portion 15, the second layer and the second ′ layer (−45 ° fiber reinforced resin layer) are interrupted, so that the second portion 14 connected to the rear of the third portion 15 is the first layer, A 12-layer structure having no 1 'layer, 2nd layer, 2' layer, 3rd layer and 3 'layer is obtained.

  At the rear end of the second portion 14, the fifth layer and the 5 'layer (90 ° fiber reinforced resin layer) are interrupted. Therefore, the first portion 13 connected to the rear of the second portion 14 is the first layer, the first layer It has a 10-layer structure without the 'layer, the second layer, the second' layer, the third layer, the third 'layer, the fifth layer and the fifth' layer.

  The rear end portion 17 connected to the rear end of the first portion 13 is the same as the second portion 14 by adding a short fifth layer and a fifth 5 ′ layer (90 ° fiber reinforced resin layer) to the first portion 13. It has a 12-layer structure.

  The rear side frame 11 having such a structure cuts a prepreg obtained by impregnating a sheet of carbon continuous fibers aligned in one direction with a thermosetting resin into a predetermined shape, and heat cures the resin in a state where a plurality of prepregs are laminated. It is manufactured by. In this case, in this embodiment, by changing the cutting direction of one kind of prepreg, a 0 ° fiber reinforced resin layer, a ± 45 ° fiber reinforced resin layer, and a 90 ° fiber reinforced resin layer can be obtained. The stacked state shown in the table of FIG. 4 can be realized by changing the lengths of the prepregs in the front-rear direction and by shifting the position in the front-rear direction.

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

  When the automobile receives a rear collision and a forward collision load is input to the rear bumper beam 12, the collision load is input from the rear bumper beam 12 to the rear end portion 17 of the rear side frame 11 through the flange 17a as a longitudinal compression load. Then, the rear side frame 11 is crushed in the front-rear direction by this compressive load to absorb the collision energy.

  At that time, the rear side frame 11 is composed of a 0 ° fiber reinforced resin layer and an inclined fiber reinforced resin layer (± 45 ° fiber reinforced resin layer and 90 ° fiber reinforced resin layer). Since the number of layers of the inclined fiber reinforced resin layer increases from the near first portion 13 toward the fourth portion 16 which is far from the first portion 13, that is, the number of the inclined fiber reinforced resin layers is eight in the first portion 13 and the second portion 14. Is 10 layers, the third portion 15 is 12 layers, and the fourth portion 16 is 14 layers. Therefore, the strength of the 0 ° fiber reinforced resin layer that is easy to buckle because the continuous fibers are parallel to the input direction of the load is from the rear to the front. It can reinforce with the inclination fiber reinforced resin layer so that it may increase gradually toward it.

  As a result, the 0 ° fiber reinforced resin layer of the first portion 13 in the vicinity of the rear end portion 17 is easily bent to reduce the initial load, and the 0 ° fiber reinforced resin layer is applied to the opposite front end portion. By making it difficult to bend, it is possible to increase the energy absorption amount by sequentially crushing the rear side frame 11 from the rear end toward the front end without inclining the rear side frame 11 with respect to the input direction of the load. As a result, a sufficient amount of energy absorption can be secured while reducing the weight of the rear side frame 11 and reducing the weight.

  FIG. 5 is a graph showing the relationship between the deformation stroke of the rear side frame 11 due to the collision load and the load.

  The broken line is a theoretical value in the case where the rear side frame 11 is composed of only the 0 ° fiber reinforced resin layer, and a large load is generated with respect to the deformation stroke, and a high energy absorption effect is expected. The chain line is an actual measurement value with respect to the theoretical value, and the generated load is significantly reduced compared to the theoretical value. The reason is that the 0 ° fiber reinforced resin layer breaks the resin by the initial load input in the axial direction and the continuous fiber bends, so that a sufficient load cannot be generated. The solid line shows this embodiment. By covering the 0 ° fiber reinforced resin layer with the inclined fiber reinforced resin layer, the 0 ° fiber reinforced resin layer is crushed in the axial direction without bending, and a sufficient load is generated. It becomes possible to do. In addition, by sequentially increasing the number of inclined fiber reinforced resin layers from the first portion 13 toward the fourth portion 16, it is possible to gradually increase the load according to an increase in the deformation stroke.

  In addition, since the tilted fiber reinforced resin layer includes those with a fiber orientation angle of 90 °, the tilted fiber reinforced resin layer with a fiber orientation angle of 90 ° increases the buckling strength of the 0 ° fiber reinforced resin layer and suppresses out-of-plane deformation. By doing so, the energy absorption amount of the 0 ° fiber reinforced resin layer can be effectively increased.

  Further, since the rear end portion 17 of the rear side frame 11 includes a flange 17a inclined obliquely with respect to the front-rear direction, a load in the vehicle width direction is applied to the rear end portion 17 by the input of the collision load of the rear collision, and the rear side frame 11 Although the bending moment is applied, the rear end portion 17 has a larger number of inclined fiber reinforced resin layers than the first portion 13 that is continuous to the fifth portion and the 5 ′ layer. Thus, the collision load can be transmitted toward the front end of the rear side frame 11.

  Further, since the rear side frame 11 increases in the number of 0 ° fiber reinforced resin layers from the first portion 13 continuing to the rear end portion 17 toward the fourth portion 16, that is, the fourth portion 16 is composed of the first to third portions. Since the first, first, and first ′ layer 0 ° fiber reinforced resin layers 13, 14, and 15 do not have, a rear end portion 17 collision load is input and a large bending moment acts on the opposite fourth portion 16. Even so, it is possible to prevent the bending of the fourth portion 16 having a large number of laminated layers of 0 ° fiber reinforced resin layers and to secure an energy absorption amount.

  Further, since the inclined fiber reinforced resin layers (the ninth layer and the ninth 'layer) laminated on the outermost side and the innermost side of the rear side frame 11 have a fiber orientation angle of 45 °, they are inclined with respect to the front-rear direction. Even when a collision load is input to the rear side frame, it is possible to suppress the bending of the rear side frame 11 and secure an energy absorption amount.

  Further, the fiber reinforced resin layers of the first layer to the ninth layer and the first 'layer to the ninth' layer are composed of one type of prepreg obtained by consolidating continuous fibers aligned in the same direction with a resin. The material cost can be reduced by forming a plurality of fiber reinforced resin layers by cutting in different directions. Moreover, since the length of the prepreg differs depending on the fiber reinforced resin layers of the first layer to the ninth layer and the first 'layer to the ninth' layer, the strength of the prepreg is minimized by minimizing the number of seams of the prepreg. While increasing, the number of laminated fiber reinforced resin layers can be changed in each part of the rear side frame 11.

Second embodiment

  Next, a second embodiment of the present invention will be described with reference to FIGS. The members corresponding to the first embodiment are indicated using the same reference numerals.

  As shown in FIGS. 6 to 8, the front surface of the cross member 113 extending in the vehicle width direction is fixed to mounting flanges 112, 112 provided at the rear ends of the pair of left and right rear side frames 11, 11. The cross member 113 is a member having a hollow closed cross section made of CFRP like the rear side frames 11, 11, and the carbon continuous fiber as the aggregate is arranged along the longitudinal direction (vehicle width direction) of the cross member 113.

  The cross member 113 is a member that is curved in an arc shape so that the central portion in the vehicle width direction protrudes rearward, and is formed by connecting a plate-like rear member 113a and a front member 113b having a hat-shaped cross-section with the rear surface open. Constructed in a closed section. The vertical height of the cross member 113 is constant in the vehicle width direction, but the thickness in the front-rear direction is large at the center in the vehicle width direction and small at both ends in the vehicle width direction.

  A bumper beam 114 divided into three in the vehicle width direction is attached to the rear surface of the cross member 113. The bumper beam 114 includes a center member 114C located at the center in the vehicle width direction and a pair of left and right end members 114L and 114R located on both left and right sides of the center member 114C. The left and right end members 114L and 114R The shape is symmetrical with respect to the surface.

  The central member 114C is a CFRP member having carbon discontinuous fibers as an aggregate, and includes a flat connecting wall 114a, a plurality of vertical ribs 114b formed on the rear surface of the connecting wall 114a, and a rear surface of the connecting wall 114a. Are formed, and the vertical ribs 114b extending in the vertical direction and the horizontal ribs 114c extending in the left-right direction intersect with each other at a lattice point 114d. The vertical ribs 114b are not formed on the left and right side edges of the connecting wall 114a, and the horizontal ribs 114c are not formed on the upper and lower edges of the connecting wall 114a. It is located inside the peripheral edge of 114a. The vertical ribs 114b and the horizontal ribs 114c are reduced in height from the lattice points 114d closest to the periphery of the connecting wall 114a toward the periphery.

  A plurality of nuts 115 are embedded in the front surface of the rear member 113a of the cross member 113, and a plurality of bolts 116 penetrating through the connecting wall 114a of the central member 114C from the rear to the front are fastened to the plurality of nuts 115. Thus, the central member 114C is detachably attached to the rear surface of the cross member 113.

  The left and right end members 114L and 114R have substantially the same structure as the above-described center member 114C, but the compressive strength in the input direction (front-rear direction) of the collision load is different between the center member 114C and the end members 114L and 114R. Is different. That is, the thickness of the longitudinal ribs 114b and the lateral ribs 114c of the central member 114C is made larger than the thickness of the longitudinal ribs 114b and the lateral ribs 114c of the end members 114L and 114R, thereby increasing the compressive strength of both. Make a difference. Further, as shown in FIG. 10, the density of the longitudinal ribs 114b,..., The lateral ribs 114c, and the lattice points 114d of the central member 114C is made denser than that of the end members 114L and 114R, thereby compressing both of them. You may make a difference.

  Since the central member 114C and the end members 114L and 114R of the bumper beam 114 have a complicated shape having a plurality of vertical ribs 114b and horizontal ribs 114c, they are press-molded using a mold. That is, a female mold having a concave cavity and a male mold having a convex core are opened, and a prepreg in which a carbon discontinuous fiber mat is impregnated with a thermoplastic resin (nylon 6, nylon 66, polypropylene, etc.) is preliminarily prepared. The center member 114C and the end members 114L and 114R are molded by placing the sample on the upper part of the female cavity in a heated state, closing the mold, press-molding, and cooling.

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

  If a part of the bumper beam 114 of the rear bumper is damaged due to a rear collision, the replacement cost increases if the entire bumper beam 114 is replaced. However, according to the present embodiment, the bumper beam 114 moves in the vehicle width direction. Since it is divided into a central member 114C located at the center and end members 114L and 114R located on both sides in the vehicle width direction, only the damaged portion is replaced and the undamaged portion is used continuously. Repair costs can be reduced. At this time, since the central member 114C and the end members 114L and 114R are detachably fixed by bolts 116 that are screwed into nuts 115 that are embedded in the cross member 113, the replacement work is extremely easy. In addition, by dividing the bumper beam 114 into three, the mold for manufacturing the bumper beam 114 can be reduced in size and the initial investment can be reduced.

  A collision load is input to the central member 114C and the left and right end members 114L and 114R at the time of a full lap collision during high-speed traveling such as cruising, and the center member 114C and the left and right end members 114L and 114R are input to the central member 114C and the left and right end members 114L and 114R at a 70% lap collision. Although the collision load is input, the required energy absorption performance is ensured by making the compressive strength of the central member 114C to which the collision load is input higher than the compressive strength of the end members 114L and 114R in any of the above cases. Can do. Further, when traveling at a low speed such as in a garage, there is a high possibility that a collision load is input to the end members 114L and 114R, but the collision load at that time is relatively small. Therefore, the weight of the bumper beam 114 can be reduced by making the compressive strength of the end members 114L and 114R lower than the compressive strength of the central member 114C.

  Thus, by dividing the bumper beam 114 into the central member 114C and the end members 114L and 114R, it is possible to easily achieve both energy absorption performance and weight reduction of the bumper beam 114.

  Further, when a collision load is input to the bumper beam 114, the longitudinal ribs 114b,..., The lateral ribs 114c and the lattice points 114d that protrude rearward from the connection wall 114a are crushed and absorb the collision energy. Vertical ribs 114b are not formed at the edges, and horizontal ribs 114c are not formed at the upper and lower edges of the connecting wall 114a, and the lattice points 114d are inside the peripheral edge of the connecting wall 114a. Therefore, not only does the high-strength lattice point 114d collapse, and a large energy absorption effect is exhibited, but the lattice point 114d does not exist on the periphery of the connecting wall 114a, so the vertical rib 114b. Further, the remaining ribs 114c are not crushed and the energy absorption effect is enhanced.

  As described above, since the vertical ribs 114b, the horizontal ribs 114c, and the lattice points 114d are crushed without being crushed, the amount of energy absorbed by the bumper beam 114 increases, and accordingly, the cross member 113 and the rear side frame 11, 11 (energy absorption amount) can be reduced, and the overall weight of the vehicle can be reduced (see FIG. 9).

  Moreover, since the vertical ribs 114b and the horizontal ribs 114c are reduced in height from the lattice points 114d closest to the periphery of the connecting wall 114a toward the periphery, the bumper face 117 that covers the bumper beam 114 (FIG. 8). ) Is less likely to interfere with the vertical ribs 114b and the horizontal ribs 114c, and the bumper face 117 can be brought close to the bumper beam 114 to reduce the size of the vehicle body.

  In addition, since the cross-sectional area of the cross member 113 increases from the end in the vehicle width direction toward the center in the vehicle width direction (see FIG. 8), shear failure at the center of the cross member 113 to which a large collision load is input during high-speed collisions. Can be prevented.

  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 side frame of the present invention is not limited to the rear side frame 11 of the embodiment, and may be a front side frame.

  Although the rear side frame 11 of the embodiment includes the rear end portion 17, the rear end portion 17 is not always necessary, and the first portion 13 may be located at the rear end of the rear side frame 11.

  Moreover, although the rear side frame 11 of the embodiment is divided into the first portion 13 to the fourth portion 16, the division is arbitrary, and the number of laminated fiber reinforced resin layers in each portion is also arbitrary.

  The fiber reinforced resin of the present invention is not limited to the CFRP (carbon fiber reinforced resin) of the embodiment, and may be other types of FRP such as GFRP (glass fiber reinforced resin).

  The present invention relates to an automobile in which a side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body is configured by laminating a plurality of fiber reinforced resin layers having different fiber orientation angles with respect to the front-rear direction. Relates to the body structure.

  In a thick cylindrical body made of FRP (fiber reinforced resin), the outer layer portion has a fiber orientation angle of 90 ° (axial direction perpendicular to the fiber) more than 0 ° (axial direction) fiber, and the inner layer portion By increasing the number of fibers with a fiber orientation angle of 0 ° (axial direction) to 90 ° (axial direction), the outer layer can be prevented from peeling off when an axial load is input. The thing which enabled absorption is known by the following patent document 1.

  In addition, a shock absorbing member divided into 12 cells is provided in front of the bumper beam arranged in the vehicle width direction at the front of the vehicle body, and the front surface of the shock absorbing member is covered with a soft bumper face, thereby At the time of a collision, only a few cells are deformed with a large stroke to keep the impact small, and at the time of a collision with other vehicles, many cells are deformed with a small stroke to minimize vehicle damage. It is known from Patent Document 2 below.

Japanese Patent No. 3833718 Japanese Unexamined Patent Publication No. 2004-237810

  By the way, in the thing of the said patent document 1, since the fiber orientation angle of an outer layer part and an inner layer part is constant along the longitudinal direction (axial direction) of a cylindrical body, the load of an axial direction is applied to the one end part of a cylindrical body. When it is input, the other end side where a large bending moment acts is bent, and the cylindrical body inclines with respect to the input direction of the load, so that it collapses sequentially from one end side to the other end side. There is a possibility that efficient energy absorption cannot be performed.

  Further, in the above-mentioned Patent Document 2, since the bumper beam is composed of a member having a hollow closed cross section integrally formed of metal or fiber reinforced resin, a part of the bumper beam is damaged by a collision. However, there is a problem that the repair cost increases because it is necessary to replace the entire bumper beam. Moreover, since the shock absorbing member is composed of 12 cells having the same structure, there is a problem that the energy absorption amount cannot be adjusted according to the position where the collision load is input.

  The present invention has been made in view of the above-mentioned circumstances, and enhances the energy absorption effect of the side frame made of fiber reinforced resin having a cylindrical closed cross section, and the repair cost when the bumper beam is damaged is small, and also the collision An object of the present invention is to provide a vehicle body structure capable of easily adjusting the energy absorption amount of a bumper beam according to a position where a load is input.

In order to achieve the above object, according to the first feature of the present invention, a side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body is provided with a fiber orientation angle of continuous fibers relative to the front-rear direction A plurality of fiber reinforced resin layers are laminated to form a vehicle body structure, and the plurality of fiber reinforced resin layers have a fiber orientation angle of 0 ° and a fiber orientation angle of 0 °. The inclined fiber reinforced resin layer other than 0 °, and the number of the laminated inclined fiber reinforced resin layers increases from the vicinity of the load input end of the side frame toward the opposite end , and the load input end The vehicle body has a load input surface that is inclined obliquely with respect to the front-rear direction, and the number of the laminated layers of the inclined fiber reinforced resin layers is larger than the vicinity of the load input end portion. Is done.

According to a second feature of the present invention, in addition to the first feature, at least one of the inclined fiber reinforced resin layers has a fiber orientation angle of 90 °. Is proposed .

According to a third aspect of the or invention, in addition to the first or second feature, the side frame, toward the opposite end from the vicinity of the load input end, the 0 ° An automobile body structure is proposed in which the number of laminated fiber reinforced resin layers is increased.

According to the fourth feature of the present invention, in addition to any one of the first to third features, the inclined fiber reinforced resin layer laminated at least on the outermost side in the laminating direction and on the innermost side in the laminating direction, A vehicle body structure is proposed in which the fiber orientation angle is 45 ° or -45 °.

According to a fifth feature of the present invention, in addition to any one of the first to fourth features, the plurality of fiber reinforced resin layers are formed by consolidating continuous fibers arranged in the same direction with a resin. A vehicle body structure characterized by comprising one type of prepreg is proposed.

According to a sixth aspect of the present invention, in addition to the fifth aspect, the prepreg has a length in the front-rear direction that differs depending on the plurality of fiber reinforced resin layers. A structure is proposed.

In order to achieve the above object, according to a seventh aspect of the present invention, a side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body has a fiber orientation angle of continuous fibers with respect to the front-rear direction. A plurality of fiber reinforced resin layers are laminated to form a vehicle body structure, and the plurality of fiber reinforced resin layers have a fiber orientation angle of 0 ° and a fiber orientation angle of 0 °. The inclined fiber reinforced resin layer other than 0 °, and the number of the laminated inclined fiber reinforced resin layers increases from the vicinity of the load input end of the side frame toward the opposite end , A bumper beam made of discontinuous fiber reinforced resin that absorbs energy by connecting a cross member made of continuous fiber reinforced resin extending in the vehicle width direction to the end and compressing and deforming the cross member on the outer surface in the front-rear direction. The And the bumper beam comprises a central member disposed at the center in the vehicle width direction and a pair of end members disposed on both sides of the central member in the vehicle width direction. Also proposed is a vehicle body structure characterized by high compressive strength.

According to an eighth feature of the present invention, in addition to the seventh feature, the bumper beam includes a plurality of vertical ribs and a plurality of horizontal ribs arranged in a lattice pattern, and the vertical ribs and the horizontal ribs. A vehicle body structure for an automobile is proposed in which the lattice points where the ribs intersect are located inside the periphery of the bumper beam.

According to a ninth feature of the present invention, in addition to the eighth feature, the density of the lattice points of the central member is higher than the density of the lattice points of the end member. A car body structure is proposed.

According to the tenth feature of the present invention, in addition to any one of the seventh to ninth features, the cross-sectional area of the cross member is from the vehicle width direction end portion toward the vehicle width direction center portion. A vehicle body structure characterized by an increase is proposed.

According to an eleventh feature of the present invention, in addition to any one of the seventh to tenth features, a nut is fixed to the cross member, and a bolt that penetrates the bumper beam is fastened to the nut. A vehicle body structure characterized by this is proposed.

  The rear side frame 11 of the embodiment corresponds to the side frame of the present invention, the rear end portion 17 of the embodiment corresponds to the load input end of the present invention, and the flange 17a of the embodiment corresponds to the load of the present invention. Corresponds to the input surface.

  According to the first aspect of the present invention, the side frame having a cylindrical closed cross section disposed in the front-rear direction at the front part of the vehicle body or the rear part of the vehicle body has a plurality of fiber reinforced resin layers having different fiber orientation angles with respect to the front-rear direction. It is constituted by laminating. The plurality of fiber reinforced resin layers are composed of a 0 ° fiber reinforced resin layer having a fiber orientation angle of 0 ° and a tilted fiber reinforced resin layer having a fiber orientation angle other than 0 °. Since it increases from the vicinity of the load input end of the side frame toward the opposite end, the 0 ° fiber reinforced resin layer in the vicinity of the load input end can be easily bent to reduce the initial load and load input. By making it difficult for the 0 ° fiber reinforced resin layer to bend toward the end opposite to the end, the side frame is crushed sequentially in the front-rear direction without inclining the load input direction. Can be increased. As a result, a sufficient amount of energy absorption can be ensured while reducing the weight by reducing the thickness of the side frames.

In addition, since the load input end has a load input surface inclined obliquely with respect to the front-rear direction, a bending moment acts on the load input end due to the collision load input. Since the number of the inclined fiber reinforced resin layers is larger than that in the vicinity, the bending load can be prevented and the collision load can be transmitted toward the opposite end.

According to the second feature of the present invention, since at least one of the inclined fiber reinforced resin layers has a fiber orientation angle of 90 °, the inclined fiber reinforced resin layer having a fiber orientation angle of 90 ° is a 0 ° fiber reinforced resin. By suppressing the out-of-plane deformation by increasing the buckling strength of the layer, it is possible to increase the energy absorption of the 0 ° fiber reinforced resin layer, and in addition, the inclined fiber reinforced resin in the process of side crushing in the front-rear direction The amount of energy absorption can be increased sequentially by increasing the number of layers .

According to a third aspect of the or invention, the side frame toward the end portion on the opposite side from the vicinity of the load input end, since the number of stacked 0 ° fiber-reinforced resin layer is increased, the load input end Even if a collision load is input to the opposite end and a large bending moment acts on the opposite end, bending of the opposite end with a large number of 0 ° fiber reinforced resin layers is prevented to ensure energy absorption. be able to.

According to the fourth aspect of the present invention, the inclined fiber reinforced resin layer laminated at least on the outermost side in the laminating direction and on the innermost side in the laminating direction has a fiber orientation angle of 45 ° or −45 °, so On the other hand, even when the collision load is input obliquely, the side frame can be prevented from bending and the amount of energy absorption can be ensured.

According to the fifth feature of the present invention, the plurality of fiber reinforced resin layers are composed of one type of prepreg obtained by consolidating continuous fibers arranged in the same direction with a resin, so that one type of prepreg is cut in different directions. Thus, the material cost can be reduced by forming a plurality of fiber reinforced resin layers.

According to the sixth aspect of the present invention, the prepreg has different lengths in the front-rear direction depending on the plurality of fiber reinforced resin layers, so that the side frame can be increased while minimizing the number of seams of the prepreg and increasing the strength. The number of laminated fiber reinforced resin layers can be changed in each part.

According to a seventh aspect of the present invention, a cross member made of continuous fiber reinforced resin extending in the vehicle width direction is connected to the ends of a pair of left and right continuous fiber reinforced resin side frames extending in the front-rear direction. A bumper beam made of discontinuous fiber reinforced resin that absorbs energy by receiving a collision load on the outer surface in the front-rear direction of the member and compressing it is supported. The bumper beam is composed of a central member arranged at the center in the vehicle width direction and a pair of end members arranged on both sides of the central member in the vehicle width direction. Therefore, when a part of the bumper beam is damaged, the bumper beam is damaged. Repair cost can be reduced by replacing only the central member or the end member. In addition, since the central member has higher compressive strength than the end member, it is possible not only to increase the energy absorption amount of the central member, which is highly likely to receive a collision load during high speed traveling such as cruising, but also during low speed traveling such as garage storage. It is possible to reduce the weight of the end member that is highly likely to receive a load, thereby making it possible to achieve both energy absorption and weight reduction of the bumper beam. Furthermore, by dividing the bumper beam into three parts, it is possible to reduce the initial investment by reducing the size of the mold for manufacturing the bumper beam.

According to an eighth aspect of the present invention, the bumper beam includes a plurality of vertical ribs and a plurality of horizontal ribs arranged in a lattice pattern, and the lattice point where the vertical ribs and the horizontal rib intersect is more than the periphery of the bumper beam. Because it is located on the inside, the lattice points with high rigidity are crushed by the collision load, and not only a large energy absorption effect is exhibited, but also the lattice points located on the inner side of the periphery of the bumper beam are crushed so that the vertical and horizontal ribs As a result, the energy absorption effect is further enhanced, and the protrusion height of the vertical and horizontal ribs at the periphery of the bumper beam is reduced, so that the bumper beam can be prevented from interfering with the bumper face.

According to the ninth feature of the present invention, since the density of the lattice points of the central member is higher than the density of the lattice points of the end member, the central member is highly likely to receive a large collision load compared to the end member. This strength can be higher than the strength of the end member.

According to the tenth feature of the present invention, since the cross-sectional area of the cross member increases from the end in the vehicle width direction toward the center in the vehicle width direction, the center of the cross member to which a large collision load is input during a high-speed collision. Can be prevented.

According to the eleventh feature of the present invention, the nut is fixed to the cross member, and the bolt that penetrates the bumper beam is fastened to the nut. Therefore, the bumper beam can be easily attached to and detached from the cross member. It is easy to change the bumper beam.

FIG. 1 is a plan view of a rear skeleton of an automobile. (First embodiment) FIG. 2 is a view in the direction of the arrow 2 in FIG. (First embodiment) FIG. 3 is a view showing a laminated state of the fiber reinforced resin layer of the rear side frame. (First embodiment) FIG. 4 is a table showing the laminated state of the fiber reinforced resin layers of the rear side frame. (First embodiment) FIG. 5 is a graph showing the relationship between the rear side frame deformation stroke and the load due to the collision load. (First embodiment) FIG. 6 is a plan view showing the skeleton of the rear part of the vehicle body. (Second Embodiment) 7 is a view in the direction of arrow 7 in FIG. (Second Embodiment) 8 is a cross-sectional view taken along line 8A-8A and a cross-sectional view taken along line 8B-8B in FIG. (Second Embodiment) FIG. 9 is a graph showing the relationship between the rear bumper stroke and the generated load due to a rear collision. (Second Embodiment) FIG. 10 is a diagram showing another embodiment of the bumper beam. (Second Embodiment)

11 Rear side frame (side frame)
17 Rear end (load input end)
17a Flange (Load input surface)
113 Cross member 114 Bumper beam 114C Central member 114L, 114R End member 114b Vertical rib 114c Horizontal rib 114d Lattice point 115 Nut 116 Bolt

  Embodiments of the present invention will be described with reference to the accompanying drawings. 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.

First embodiment

  First, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a pair of left and right rear side frames 11, 11 are arranged in the front-rear direction at the rear part of the vehicle body, and a rear bumper beam extending between the rear ends of the left and right rear side frames 11, 11 in the vehicle width direction. 12 is connected. The rear side frames 11 and 11 and the rear bumper beam 12 are made of CFRP (carbon fiber reinforced resin) in which continuous fiber layers in which carbon continuous fibers are aligned in one direction are laminated in a plurality of layers and hardened with a resin.

  As shown in FIG. 2, the rear side frame 11 is a hollow cylindrical member having a rectangular cross section, and is divided into four parts having different numbers of laminated fiber reinforced resin layers. That is, the rear side frame 11 is divided into a first portion 13, a second portion 14, a third portion 15, and a fourth portion 16 in order from the rear end side where the collision load of the rear collision is input to the front end side. A short rear end portion 17 is provided behind the first portion 13. A flat flange 17 a is provided on the rear surface of the rear end portion 17, and the flange 17 a is fixed to the front surface of the rear bumper beam 12. The flange 17a is inclined so that the outer end in the vehicle width direction is biased forward (see FIG. 1).

  As shown in FIGS. 2 to 4, the number of laminated fiber reinforced resin layers of the rear side frame 11 is such that the first portion 13 is 10 layers, the second portion 14 is 12 layers, and the third portion 15 is 14 layers. The fourth portion 16 has 18 layers, and the rear end portion 17 has 12 layers. The fiber reinforced resin layer of each part is laminated | stacked symmetrically in the surface side and the back surface side with respect to the symmetrical surface of the lamination direction center. The fiber orientation angle of the continuous fibers of the fiber reinforced resin layer is defined by an angle with respect to the longitudinal direction (front-rear direction) of the rear side frame 11, 0 ° indicates parallel to the longitudinal direction, and ± 45 ° indicates relative to the longitudinal direction. The angle is 45 ° to the left and right, and 90 ° indicates that it intersects the longitudinal direction at 90 °.

  In the fourth portion 16 laminated in 18 layers, the first layer to the ninth layer are laminated outside the symmetry plane, and the first ′ layer to the 9 ′ layer are laminated inside the symmetry plane. The first and first layers on both sides of the symmetry plane are 0 ° fiber reinforced resin layers, and the second, third and second 'and 3' layers on both sides of the symmetry plane are ± 45 ° fiber reinforced resin layers. The fourth layer and the 4 'layer on both sides of the symmetry plane are 0 ° fiber reinforced resin layers, and the fifth to seventh layers and the 5' to 7 'layers on both sides of the symmetry surface are 90 ° fiber reinforced resin layers. The 8th and 9th layers and the 8 'and 9' layers on both sides of the symmetry plane are ± 45 ° fiber reinforced resin layers.

  At the rear end of the fourth portion 16, the first layer and the first 'layer (0 ° fiber reinforced resin layer) are disconnected from the third layer and the third' layer (45 ° fiber reinforced resin layer). The third portion 15 connected to the rear of the fourth portion 16 has a 14-layer structure without the first layer, the first 'layer, the third layer, and the third' layer.

  At the rear end of the third portion 15, the second layer and the second ′ layer (−45 ° fiber reinforced resin layer) are interrupted, so that the second portion 14 connected to the rear of the third portion 15 is the first layer, A 12-layer structure having no 1 'layer, 2nd layer, 2' layer, 3rd layer and 3 'layer is obtained.

  At the rear end of the second portion 14, the fifth layer and the 5 'layer (90 ° fiber reinforced resin layer) are interrupted. Therefore, the first portion 13 connected to the rear of the second portion 14 is the first layer, the first layer It has a 10-layer structure without the 'layer, the second layer, the second' layer, the third layer, the third 'layer, the fifth layer and the fifth' layer.

  The rear end portion 17 connected to the rear end of the first portion 13 is the same as the second portion 14 by adding a short fifth layer and a fifth 5 ′ layer (90 ° fiber reinforced resin layer) to the first portion 13. It has a 12-layer structure.

  The rear side frame 11 having such a structure cuts a prepreg obtained by impregnating a sheet of carbon continuous fibers aligned in one direction with a thermosetting resin into a predetermined shape, and heat cures the resin in a state where a plurality of prepregs are laminated. It is manufactured by. In this case, in this embodiment, by changing the cutting direction of one kind of prepreg, a 0 ° fiber reinforced resin layer, a ± 45 ° fiber reinforced resin layer, and a 90 ° fiber reinforced resin layer can be obtained. The stacked state shown in the table of FIG. 4 can be realized by changing the lengths of the prepregs in the front-rear direction and by shifting the position in the front-rear direction.

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

  When the automobile receives a rear collision and a forward collision load is input to the rear bumper beam 12, the collision load is input from the rear bumper beam 12 to the rear end portion 17 of the rear side frame 11 through the flange 17a as a longitudinal compression load. Then, the rear side frame 11 is crushed in the front-rear direction by this compressive load to absorb the collision energy.

  At that time, the rear side frame 11 is composed of a 0 ° fiber reinforced resin layer and an inclined fiber reinforced resin layer (± 45 ° fiber reinforced resin layer and 90 ° fiber reinforced resin layer). Since the number of layers of the inclined fiber reinforced resin layer increases from the near first portion 13 toward the fourth portion 16 which is far from the first portion 13, that is, the number of the inclined fiber reinforced resin layers is eight in the first portion 13 and the second portion 14. Is 10 layers, the third portion 15 is 12 layers, and the fourth portion 16 is 14 layers. Therefore, the strength of the 0 ° fiber reinforced resin layer that is easy to buckle because the continuous fibers are parallel to the input direction of the load is from the rear to the front. It can reinforce with the inclination fiber reinforced resin layer so that it may increase gradually toward it.

  As a result, the 0 ° fiber reinforced resin layer of the first portion 13 in the vicinity of the rear end portion 17 is easily bent to reduce the initial load, and the 0 ° fiber reinforced resin layer is applied to the opposite front end portion. By making it difficult to bend, it is possible to increase the energy absorption amount by sequentially crushing the rear side frame 11 from the rear end toward the front end without inclining the rear side frame 11 with respect to the input direction of the load. As a result, a sufficient amount of energy absorption can be secured while reducing the weight of the rear side frame 11 and reducing the weight.

  FIG. 5 is a graph showing the relationship between the deformation stroke of the rear side frame 11 due to the collision load and the load.

  The broken line is a theoretical value in the case where the rear side frame 11 is composed of only the 0 ° fiber reinforced resin layer, and a large load is generated with respect to the deformation stroke, and a high energy absorption effect is expected. The chain line is an actual measurement value with respect to the theoretical value, and the generated load is significantly reduced compared to the theoretical value. The reason is that the 0 ° fiber reinforced resin layer breaks the resin by the initial load input in the axial direction and the continuous fiber bends, so that a sufficient load cannot be generated. The solid line shows this embodiment. By covering the 0 ° fiber reinforced resin layer with the inclined fiber reinforced resin layer, the 0 ° fiber reinforced resin layer is crushed in the axial direction without bending, and a sufficient load is generated. It becomes possible to do. In addition, by sequentially increasing the number of inclined fiber reinforced resin layers from the first portion 13 toward the fourth portion 16, it is possible to gradually increase the load according to an increase in the deformation stroke.

  In addition, since the tilted fiber reinforced resin layer includes those with a fiber orientation angle of 90 °, the tilted fiber reinforced resin layer with a fiber orientation angle of 90 ° increases the buckling strength of the 0 ° fiber reinforced resin layer and suppresses out-of-plane deformation. By doing so, the energy absorption amount of the 0 ° fiber reinforced resin layer can be effectively increased.

  Further, since the rear end portion 17 of the rear side frame 11 includes a flange 17a inclined obliquely with respect to the front-rear direction, a load in the vehicle width direction is applied to the rear end portion 17 by the input of the collision load of the rear collision, and the rear side frame 11 Although the bending moment is applied, the rear end portion 17 has a larger number of inclined fiber reinforced resin layers than the first portion 13 that is continuous to the fifth portion and the 5 ′ layer. Thus, the collision load can be transmitted toward the front end of the rear side frame 11.

  Further, since the rear side frame 11 increases in the number of 0 ° fiber reinforced resin layers from the first portion 13 continuing to the rear end portion 17 toward the fourth portion 16, that is, the fourth portion 16 is composed of the first to third portions. Since the first, first, and first ′ layer 0 ° fiber reinforced resin layers 13, 14, and 15 do not have, a rear end portion 17 collision load is input and a large bending moment acts on the opposite fourth portion 16. Even so, it is possible to prevent the bending of the fourth portion 16 having a large number of laminated layers of 0 ° fiber reinforced resin layers and to secure an energy absorption amount.

  Further, since the inclined fiber reinforced resin layers (the ninth layer and the ninth 'layer) laminated on the outermost side and the innermost side of the rear side frame 11 have a fiber orientation angle of 45 °, they are inclined with respect to the front-rear direction. Even when a collision load is input to the rear side frame, it is possible to suppress the bending of the rear side frame 11 and secure an energy absorption amount.

  Further, the fiber reinforced resin layers of the first layer to the ninth layer and the first 'layer to the ninth' layer are composed of one type of prepreg obtained by consolidating continuous fibers aligned in the same direction with a resin. The material cost can be reduced by forming a plurality of fiber reinforced resin layers by cutting in different directions. Moreover, since the length of the prepreg differs depending on the fiber reinforced resin layers of the first layer to the ninth layer and the first 'layer to the ninth' layer, the strength of the prepreg is minimized by minimizing the number of seams of the prepreg. While increasing, the number of laminated fiber reinforced resin layers can be changed in each part of the rear side frame 11.

Second embodiment

  Next, a second embodiment of the present invention will be described with reference to FIGS. The members corresponding to the first embodiment are indicated using the same reference numerals.

  As shown in FIGS. 6 to 8, the front surface of the cross member 113 extending in the vehicle width direction is fixed to mounting flanges 112, 112 provided at the rear ends of the pair of left and right rear side frames 11, 11. The cross member 113 is a member having a hollow closed cross section made of CFRP like the rear side frames 11, 11, and the carbon continuous fiber as the aggregate is arranged along the longitudinal direction (vehicle width direction) of the cross member 113.

  The cross member 113 is a member that is curved in an arc shape so that the central portion in the vehicle width direction protrudes rearward, and is formed by connecting a plate-like rear member 113a and a front member 113b having a hat-shaped cross-section with the rear surface open. Constructed in a closed section. The vertical height of the cross member 113 is constant in the vehicle width direction, but the thickness in the front-rear direction is large at the center in the vehicle width direction and small at both ends in the vehicle width direction.

  A bumper beam 114 divided into three in the vehicle width direction is attached to the rear surface of the cross member 113. The bumper beam 114 includes a center member 114C located at the center in the vehicle width direction and a pair of left and right end members 114L and 114R located on both left and right sides of the center member 114C. The left and right end members 114L and 114R The shape is symmetrical with respect to the surface.

  The central member 114C is a CFRP member having carbon discontinuous fibers as an aggregate, and includes a flat connecting wall 114a, a plurality of vertical ribs 114b formed on the rear surface of the connecting wall 114a, and a rear surface of the connecting wall 114a. Are formed, and the vertical ribs 114b extending in the vertical direction and the horizontal ribs 114c extending in the left-right direction intersect with each other at a lattice point 114d. The vertical ribs 114b are not formed on the left and right side edges of the connecting wall 114a, and the horizontal ribs 114c are not formed on the upper and lower edges of the connecting wall 114a. It is located inside the peripheral edge of 114a. The vertical ribs 114b and the horizontal ribs 114c are reduced in height from the lattice points 114d closest to the periphery of the connecting wall 114a toward the periphery.

  A plurality of nuts 115 are embedded in the front surface of the rear member 113a of the cross member 113, and a plurality of bolts 116 penetrating through the connecting wall 114a of the central member 114C from the rear to the front are fastened to the plurality of nuts 115. Thus, the central member 114C is detachably attached to the rear surface of the cross member 113.

  The left and right end members 114L and 114R have substantially the same structure as the above-described center member 114C, but the compressive strength in the input direction (front-rear direction) of the collision load is different between the center member 114C and the end members 114L and 114R. Is different. That is, the thickness of the longitudinal ribs 114b and the lateral ribs 114c of the central member 114C is made larger than the thickness of the longitudinal ribs 114b and the lateral ribs 114c of the end members 114L and 114R, thereby increasing the compressive strength of both. Make a difference. Further, as shown in FIG. 10, the density of the longitudinal ribs 114b,..., The lateral ribs 114c, and the lattice points 114d of the central member 114C is made denser than that of the end members 114L and 114R, thereby compressing both of them. You may make a difference.

  Since the central member 114C and the end members 114L and 114R of the bumper beam 114 have a complicated shape having a plurality of vertical ribs 114b and horizontal ribs 114c, they are press-molded using a mold. That is, a female mold having a concave cavity and a male mold having a convex core are opened, and a prepreg in which a carbon discontinuous fiber mat is impregnated with a thermoplastic resin (nylon 6, nylon 66, polypropylene, etc.) is preliminarily prepared. The center member 114C and the end members 114L and 114R are molded by placing the sample on the upper part of the female cavity in a heated state, closing the mold, press-molding, and cooling.

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

  If a part of the bumper beam 114 of the rear bumper is damaged due to a rear collision, the replacement cost increases if the entire bumper beam 114 is replaced. However, according to the present embodiment, the bumper beam 114 moves in the vehicle width direction. Since it is divided into a central member 114C located at the center and end members 114L and 114R located on both sides in the vehicle width direction, only the damaged portion is replaced and the undamaged portion is used continuously. Repair costs can be reduced. At this time, since the central member 114C and the end members 114L and 114R are detachably fixed by bolts 116 that are screwed into nuts 115 that are embedded in the cross member 113, the replacement work is extremely easy. In addition, by dividing the bumper beam 114 into three, the mold for manufacturing the bumper beam 114 can be reduced in size and the initial investment can be reduced.

  A collision load is input to the central member 114C and the left and right end members 114L and 114R at the time of a full lap collision during high-speed traveling such as cruising, and the center member 114C and the left and right end members 114L and 114R are input to the central member 114C and the left and right end members 114L and 114R at a 70% lap collision. Although the collision load is input, the required energy absorption performance is ensured by making the compressive strength of the central member 114C to which the collision load is input higher than the compressive strength of the end members 114L and 114R in any of the above cases. Can do. Further, when traveling at a low speed such as in a garage, there is a high possibility that a collision load is input to the end members 114L and 114R, but the collision load at that time is relatively small. Therefore, the weight of the bumper beam 114 can be reduced by making the compressive strength of the end members 114L and 114R lower than the compressive strength of the central member 114C.

  Thus, by dividing the bumper beam 114 into the central member 114C and the end members 114L and 114R, it is possible to easily achieve both energy absorption performance and weight reduction of the bumper beam 114.

  Further, when a collision load is input to the bumper beam 114, the longitudinal ribs 114b,..., The lateral ribs 114c and the lattice points 114d that protrude rearward from the connection wall 114a are crushed and absorb the collision energy. Vertical ribs 114b are not formed at the edges, and horizontal ribs 114c are not formed at the upper and lower edges of the connecting wall 114a, and the lattice points 114d are inside the peripheral edge of the connecting wall 114a. Therefore, not only does the high-strength lattice point 114d collapse, and a large energy absorption effect is exhibited, but the lattice point 114d does not exist on the periphery of the connecting wall 114a, so the vertical rib 114b. Further, the remaining ribs 114c are not crushed and the energy absorption effect is enhanced.

  As described above, since the vertical ribs 114b, the horizontal ribs 114c, and the lattice points 114d are crushed without being crushed, the amount of energy absorbed by the bumper beam 114 increases, and accordingly, the cross member 113 and the rear side frame 11, 11 (energy absorption amount) can be reduced, and the overall weight of the vehicle can be reduced (see FIG. 9).

  Moreover, since the vertical ribs 114b and the horizontal ribs 114c are reduced in height from the lattice points 114d closest to the periphery of the connecting wall 114a toward the periphery, the bumper face 117 that covers the bumper beam 114 (FIG. 8). ) Is less likely to interfere with the vertical ribs 114b and the horizontal ribs 114c, and the bumper face 117 can be brought close to the bumper beam 114 to reduce the size of the vehicle body.

  In addition, since the cross-sectional area of the cross member 113 increases from the end in the vehicle width direction toward the center in the vehicle width direction (see FIG. 8), shear failure at the center of the cross member 113 to which a large collision load is input during high-speed collisions. Can be prevented.

  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 side frame of the present invention is not limited to the rear side frame 11 of the embodiment, and may be a front side frame.

  Although the rear side frame 11 of the embodiment includes the rear end portion 17, the rear end portion 17 is not always necessary, and the first portion 13 may be located at the rear end of the rear side frame 11.

  Moreover, although the rear side frame 11 of the embodiment is divided into the first portion 13 to the fourth portion 16, the division is arbitrary, and the number of laminated fiber reinforced resin layers in each portion is also arbitrary.

The fiber reinforced resin of the present invention is not limited to the CFRP (carbon fiber reinforced resin) of the embodiment, and may be other types of FRP such as GFRP (glass fiber reinforced resin).

Claims (12)

A side frame (11) having a cylindrical closed cross section disposed in a front-rear direction or a front-rear direction of a vehicle body is configured by laminating a plurality of fiber reinforced resin layers having different fiber orientation angles with respect to the front-rear direction. A vehicle body structure,
The plurality of fiber reinforced resin layers are composed of a 0 ° fiber reinforced resin layer having a fiber orientation angle of 0 ° and a tilted fiber reinforced resin layer having a fiber orientation angle other than 0 °, and the number of the tilted fiber reinforced resin layers stacked. Increases from the vicinity of the load input end (17) of the side frame (11) toward the opposite end.   The vehicle body structure according to claim 1, wherein at least one of the inclined fiber reinforced resin layers has a fiber orientation angle of 90 °.   The load input end portion (17) includes a load input surface (17a) that is inclined obliquely with respect to the front-rear direction, and the number of the inclined fiber reinforced resin layers laminated than the vicinity of the load input end portion (17). The vehicle body structure of an automobile according to claim 1, wherein the vehicle body structure is large.   The side frame (11) is characterized in that the number of the 0 ° fiber reinforced resin layers increases from the vicinity of the load input end (17) toward the opposite end. The vehicle body structure according to any one of claims 3 to 4.   5. The inclined fiber reinforced resin layer laminated at least on the outermost side in the laminating direction and on the innermost side in the laminating direction has a fiber orientation angle of 45 [deg.] Or -45 [deg.]. 2. A vehicle body structure according to item 1.   The automobile according to any one of claims 1 to 5, wherein the plurality of fiber reinforced resin layers are made of one type of prepreg obtained by solidifying continuous fibers aligned in the same direction with a resin. Car body structure.   The vehicle body structure according to claim 6, wherein the prepreg has different lengths in the front-rear direction depending on the plurality of fiber reinforced resin layers.   A cross member (113) made of continuous fiber reinforced resin extending in the vehicle width direction is connected to the end of the side frame (11), and the outer surface of the cross member (113) is compressed and deformed by receiving a collision load. A bumper beam (114) made of discontinuous fiber reinforced resin that absorbs energy at the center is supported, and the bumper beam (114) includes a central member (114C) disposed at the center in the vehicle width direction, and It consists of a pair of end members (114L, 114R) disposed on both sides in the vehicle width direction, and the center member (114C) has a higher compressive strength than the end members (114L, 114R), The vehicle body structure according to claim 1.   The bumper beam (114) includes a plurality of vertical ribs (114b) and a plurality of horizontal ribs (114c) arranged in a lattice shape, and lattice points where the vertical ribs (114b) and the horizontal ribs (114c) intersect with each other. The vehicle body structure according to claim 8, wherein (114d) is located inside a periphery of the bumper beam (114).   The density of the lattice points (114d) of the central member (114C) is higher than the density of the lattice points (114d) of the end members (114L, 114R). Auto body structure.   11. The automobile according to claim 8, wherein a cross-sectional area of the cross member (113) increases from an end portion in the vehicle width direction toward a center portion in the vehicle width direction. Body structure.   The nut (115) is fixed to the cross member (113), and a bolt (116) passing through the bumper beam (114) is fastened to the nut (115). The vehicle body structure according to any one of the above.

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