JP2007112212A - Body frame structure of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To absorb efficiently the impact energy at the time of head-on collision even if the configuration does not allow easily securing a sufficient crushable zone in the forefront part of each front side frame. <P>SOLUTION: A crushing part 12b to crush and deform into a bellow shape at the time of head-on collision is formed at the forefront of each of a pair of front side frames 12 provided on the sides of the vehicle body across the width, while a main frame 12a having a high section strength is provided in the rear part continued to the crushing part 12b, in which the joining surfaces 12c of two members 12a and 12a are formed tapered as retreating backward aslant from inside of the vehicle body across the width toward the outside. Because the impact load F at the time of head-on collision reaches first the inside of the joining surfaces 12c, the input load becomes unbalanced, and a bending moment is generated in the main frame 12a, and a flexural deformation at that time absorbs the impact energy. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle body frame structure capable of efficiently absorbing impact energy at the time of collision even when a crushable zone cannot be sufficiently secured at the front end portion of a front side frame.

  Conventionally, a front side frame extending in the front-rear direction along the left and right front wheel aprons is opposed to an engine room in a vehicle such as an automobile, and the engine and power transmission system are opposed to both front side frames. Powertrain, which is a variety of devices, is supported.

  The front ends of both front side frames are connected by a cross member such as a bumper beam, and the impact load at the time of a frontal collision is transmitted to the front side frame via the cross member. The front side frame is deformed by axial crushing to absorb impact energy, and the impact load is distributed to the side structures such as the rear frame and front pillar that are continuous with the front side frame, so that the impact load to the cabin (vehicle compartment) To prevent the transmission of passengers and protect passengers.

  In this case, if the crushable zone is not sufficiently secured at the front end portion of the front side frame, there is a problem that the impact load is transmitted to the cabin side due to the stretching action of the side frame portion continuous behind the front side frame.

  As a countermeasure, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-31534), a fragile portion is appropriately formed in the front end portion of the front side frame and the reinforcement housed in the front side frame according to required characteristics. When a collision load is input to the front end of the frame, the weakened portion formed at the front end of the front side frame is axially crushed, and the weakened portion of the reinforcement is also axially crushed in an accordion-like deformation mode. A technique for absorbing collision energy is disclosed.

  In the technique disclosed in Patent Document 1, it is possible to absorb impact energy even in a relatively short crushable zone by combining a reinforcement and a fragile portion.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2003-312549), the front end of the side member extension joined to the lower surface of the floor panel is fitted to the lower side of the rear end of the front side frame. Is composed of an outer material having a hollow cross section and a reinforcement disposed inside, and a technique is disclosed in which the number of peaks of each bending mode waveform of the outer material and the reinforcement is set to different prime numbers.

In the technique disclosed in Patent Document 2, since the number of peaks of each bending mode waveform of the outer material and reinforcement is set to different prime numbers, the crushable zone of the front side frame is relatively short, and the impact energy is sufficiently high. Even if it cannot be absorbed, impact energy can be absorbed by the outer material and reinforcement provided in the side member extension being independently deformed.
JP 2003-31534 A JP 2003-312549 A

  However, the technique described in Patent Document 1 has a problem that the front side frame must have a double structure of the outer material and the reinforcement, which complicates the structure and increases the manufacturing cost.

  Similarly, the technique disclosed in Patent Document 2 has a problem that the side member extension must have a double structure of the outer material and the reinforcement, which complicates the structure and increases the manufacturing cost.

  In view of the above circumstances, the present invention has sufficient impact energy at the time of collision without complicating the frame structure even if it is difficult to sufficiently secure a crushable zone at the end of the front side frame. It is an object of the present invention to provide a vehicle body frame structure that can be absorbed into the vehicle body and can reduce manufacturing costs.

  In order to achieve the above object, according to the present invention, a pair of side frames extending in the front-rear direction of the vehicle body are provided on both sides in the vehicle body width direction, and the ends of the side frames are connected via a cross member. In the vehicle body frame structure, a first member that absorbs impact energy by axial crushing at the time of a collision is provided at an end of the vehicle body, and a second member having a high cross-sectional strength is provided continuously to the first member. The connecting portion between the first member and the second member is inclined in a taper shape with respect to an axis perpendicular to the central axis in the vehicle body width direction.

  According to the present invention, since the first member that promotes axial crushing and the second member having high cross-sectional strength are joined while being inclined in a taper shape, the impact load input to the second member is quicker at the distal end side of the joining portion. The rear end side arrives with a delay. As a result, the input load is unbalanced between the front end side and the rear end side of the coupling portion, a bending moment is generated in the second member, and impact energy can be absorbed by the moment load at that time. Therefore, even when it is difficult to sufficiently secure the crushable zone at the end of the front side frame, the impact energy at the time of collision can be absorbed sufficiently. Moreover, since the structure is a simple structure in which the coupling portion is inclined, the manufacturing cost can be reduced.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 5 show a first embodiment of the present invention. 1 and 2 show a vehicle body frame structure at the front of the vehicle body, FIG. 1 is a schematic plan view, and FIG. 2 is a schematic side view.

  Reference numeral 11 in the figure denotes an engine room provided at the front of the vehicle body, and a toe board 15 that partitions the engine room 11 and the cabin 14 is disposed at the rear of the engine room 11. A pair of parallel front side frames 12 formed in a closed cross-sectional shape are disposed on both sides of the engine room 11 in the vehicle body width direction. The rear portion of each front side frame 12 extends downward and rearward along the inclination of the toe board 15, and is a front end portion of a side sill (both not shown) disposed on both sides of the floor panel in the vehicle width direction. Are connected to each other.

  The front end portions of both front side frames 12 are coupled to each other via a cross member 13 such as a front cross member or a bumper beam. Further, a suspension cross member 16 that supports a front suspension (not shown) is disposed in front of the toe board 15, and both sides of the suspension cross member 16 are connected to the rear portion of each front side frame 12.

  In the engine room 11, a power unit 19 configured by combining an engine body 17 and a transmission 18 is mounted. In this embodiment, an in-line engine is shown as the engine body 17, and the power unit 19 is placed horizontally in the engine room 11. Further, both sides of the power unit 19 in the vehicle body width direction are supported and fixed to the front side frames 12 via mount brackets 20, and a substantially central rear portion attaches another mount bracket (not shown) to the suspension cross member 16. It is supported and fixed through. Reference numeral 21 denotes a radiator unit.

  The rear part of the front side frame 12 is stiffened by the suspension cross member 16, and therefore the crushable zone of the front side frame 12 is at least a region Z1 from the tip part to the attachment site of the suspension cross member 16. In this case, when the power units 19 are arranged horizontally as in the present embodiment, there is little overhang from the front suspension to the front of the vehicle body, so it is difficult to secure a crushable zone relatively long. In particular, in the structure in which the power unit 19 is supported by the front side frame 12 via the mount bracket 20, the area from the mount bracket 20 to the tip is the crushable zone region Z2, and the crushable zone is further narrowed. In this embodiment, the region Z2 is a crushable zone. Therefore, in the following description, the region Z2 will be read as the crushable zone Z2.

  The front side frame 12 includes a main frame portion 12a as a second member having a high cross-sectional strength, and a crushing portion 12b as a first member in which axial crush is induced by an impact load at the time of a frontal collision. The crushing portion 12b is set in substantially the same region as the crushable zone Z2, and the joint surface 12c, which is a connecting portion between the rear end of the crushing portion 12b and the front end of the main frame portion 12a, extends from the inside in the vehicle body width direction to the outside. It is formed in the shape of a slope that recedes obliquely backward. 3 shows the front side frame 12 on the left side in the vehicle body width direction. Further, as shown in enlarged views in FIGS. 1A and 1B, the inclination angle θ of the joint surface 12c with respect to the axis Y perpendicular to the longitudinal axis passing through the center in the vehicle body width direction is set to about 5 to 30 °. It is desirable to do.

  Accordingly, the distance when the impact load F is transmitted from the tip of the crushing portion 12b to the main frame portion 12a is short as the inside of the main frame portion 12a is short, and becomes longer as it moves outward.

  The crushing portion 12b is made of a material such as a mild steel plate or an aluminum plate that has lower rigidity than the main frame portion 12a and promotes axial crushing by an impact load at the time of a frontal collision. The crushing portion 12b may have a structure that promotes axial crushing by reducing the plate thickness.

  In this embodiment, the front side frame 12 is formed using a tailored blank material. The tailored blank material is formed by joining a steel plate blank material and a low-rigidity blank material such as a mild steel plate or aluminum plate at a position corresponding to the main frame portion 12a and the crushing portion 12b after sheet metal processing, with the joining surface 12c as a boundary. Has been formed.

  In such a configuration, when the vehicle collides front, the impact load F is input to the front end portions of the front side frames 12 via the cross member 13 that connects the front ends of the front side frames 12. Since the front ends of the left and right front side frames 12 are connected by the cross member 13, even if an impact load F is input, the reaction load does not bend inward or outward in the vehicle body width direction. Is transmitted along the axial direction to the front side frame 12.

  Then, as shown in FIG. 4, the crushing part 12b provided in the crushable zone Z2 of the front side frame 12 is axially crushed in a bellows shape to absorb impact energy. Since the crushing portion 12b is formed of a low-rigidity material, axial crushing is promoted. Further, when the impact load F at the time of frontal collision is relatively small, the impact energy is absorbed only by the axial crushing of the crushing portion 12b. be able to.

  On the other hand, when the impact load F at the time of the frontal collision is relatively large and the impact energy cannot be sufficiently absorbed only by the axial crushing of the crushing portion 12b, the remaining impact load F is transferred to the main frame portion 12a side via the crushing portion 12b. Is transmitted to.

  The joint surface 12c between the crushing portion 12b and the main frame portion 12a is formed in a taper shape that recedes obliquely backward from the inner side to the outer side in the vehicle width direction, and the transmission distance of the impact load F is short on the inner side and on the outer side. become longer. Accordingly, the impact load F first reaches the inside which is the tip of the joint surface 12c of the main frame portion 12a first, and reaches the outside of the joint surface 12c later than that. Thus, since the impact load F is first input to the inside of the main frame portion 12a, the input load is unbalanced inside and outside the main frame portion 12a, and a bending moment is generated in the main frame portion 12a.

  In this case, as described above, since the front end surfaces of the left and right front side frames 12 are connected by the cross member 13, the front end surfaces of both front side frames 12 do not enter the vehicle body width direction inside. Therefore, as shown in FIG. 5, the moment load due to this bending moment is concentrated on a relatively weak portion inside the main frame portion 12a, and the middle portion of the main frame portion 12a starts from the concentrated portion as a starting point P. It is bent and deformed so as to project outward in the width direction. The impact energy is absorbed by the bending deformation of the main frame portion 12a.

  In addition, the origin P may be made to identify the generation | occurrence | production site | part by forming a weak part previously in the middle inside the main frame part 12a. Further, the mount bracket 20 fixed to the front side frame 12 forms a weakened portion such that a screw portion for fastening the mount bracket 20 to the front side frame 12 is sheared, or the mount bracket 20 is broken. By forming the weakened portion that is promoted, the breakage is promoted without inhibiting the bending deformation of the main frame portion 12a.

  Thus, in this embodiment, even when the impact load F is relatively large and the impact energy is not sufficiently absorbed by the axial crushing of the crushing portion 12b, the remaining impact can be obtained by bending and deforming the main frame portion 12a. Since the energy can be sufficiently absorbed, the transmission of the impact load to the cabin 14 is prevented, and the occupant can be effectively protected.

  Further, since the starting point P of the main frame portion 12a is bent and deformed outward in the vehicle body width direction, the starting point P is deformed in a direction away from the power unit 19 even when the power units 19 are arranged horizontally. Therefore, the starting point P is not buffered by the engine body 17 or the transmission 18 and the bending deformation is not hindered.

  If the starting point P moves inward in the vehicle body width direction and does not buffer with the engine body 17 or the transmission 18, the joint surface 12c is inclined in the opposite direction to the main frame portion 12a. May be bent and deformed inward. Further, when the main frame portion 12a and the crushing portion 12b are formed separately, a flange may be formed on the joint surface 12c of both the members 12a and 12b, and the flange may be bolted and coupled.

  FIG. 6 shows a second embodiment of the present invention. 6A is an exploded perspective view of the main part of the front side frame, and FIG. 6B is a perspective view of the main part of the front side frame.

  In the first embodiment described above, the front side frame 12 is formed using a tailored blank material. However, the front side frame 26 according to the present embodiment has an inner frame 26a, an outer frame 26b, and a first member formed in a cross-sectional hat shape. The crushing portion 26c is formed of three parts. The closed cross-sectional shape formed by the outer frame 26b and the corresponding inner frame 26a functions as a second member having high cross-sectional strength.

  The inner frame 26a is formed over the entire length of the front side frame 26 with a relatively shallow groove depth. Therefore, the front end is connected to the cross member 13 (see FIG. 1).

  On the other hand, the outer frame 26b joined to the inner frame 26a by monaca alignment has a relatively deep groove depth. Further, the tip of the outer frame 26b is cut in the vicinity of the crushable zone Z2. Further, a crushing portion 26c having the same cross-sectional shape as the outer frame 26b is disposed at the tip of the inner frame 26a exposed from the cut portion of the outer frame 26b. The crushing portion 26c and the inner frame 26a are connected to the monaca. They are joined together.

  In FIG. 6, only the front side frame 26 on the left side in the vehicle body width direction is shown, and the front side frame 26 on the right side in the vehicle body width direction is omitted. It is formed symmetrically with the front side frame 26 on the left side in the vehicle body width direction.

  The crushing portion 26c is made of a material having a lower rigidity than the main frame portion 12a, such as a mild steel plate or an aluminum plate, or is formed using a steel plate having a thin plate thickness, so that the rigidity is reduced. Also, the joint surface 26d, which is the joint portion at the front end of the outer frame 26b, and the joint surface 26e at the rear end of the crushing portion 26c joined thereto are inclined rearward from the inner side to the outer side in the vehicle body width direction, as in the first embodiment. It is formed in a taper shape that recedes. Both joint surfaces 26d and 26e are welded via welding means such as beam welding.

  In such a configuration, when an impact load F is input to the front ends of the front side frames 26 arranged on the left and right in the vehicle body width direction, the front ends of both front side frames 26 are connected via the cross member 13. Therefore, it does not bend inward or outward in the vehicle body width direction, and the crushing portion 26c and the tip end portion of the inner frame 26a joined thereto are axially crushed.

  When the impact load F reaches the joint surfaces 26d and 26e between the rear end of the crushing portion 26c and the front end of the outer frame 26b, the joint surfaces 26d and 26e taper backward from the vehicle width direction inner side toward the outer side. Therefore, the impact load F is first input inside the joint surfaces 26d and 26e. Therefore, the input load is unbalanced inside and outside the outer frame 26b, and a bending moment is generated in the inner frame 26a. The moment load due to this bending moment is concentrated in a relatively weak portion of the inner frame 26a, and the middle of the front side frame 26 is bent and deformed outward in the vehicle body width starting from this concentrated portion. Impact energy is absorbed.

  As described above, in this embodiment, the inner side frame 26a is used as a base material, and the outer side frame 26b and the crushing portion 26c are joined to the inner frame 26a by the monaca to form the front side frame 26. Further, positioning and joining of the crushing portion 26c are facilitated, and the number of manufacturing steps can be reduced. In addition, since only the crushing portion 26c can be easily changed in design at the time of manufacture, the optimum thickness and material of the crushing portion 26c can be selected according to the characteristics of each vehicle, and the product has high reliability. Sex can be obtained.

  FIG. 7 is a perspective view showing a main part of a front side frame according to the third embodiment of the present invention. Although only the front side frame 31 on the left side in the vehicle width direction is shown in the figure, the front side frame on the right side in the vehicle width direction is formed symmetrically with the front side frame 31 on the left side in the vehicle width direction. The front side frame 31 is applied in place of the front side frame 12 of the first form, and the configuration other than the front side frame 31 is the same as that of the first form.

  The front side frame 31 according to the present embodiment is formed by separately forming a main frame part 32 having a high cross-sectional strength as a second member formed in a closed cross-sectional shape and a crushing part 33 as a first member. The rear end portion of the crushing portion 33 is inserted into the front end portion of the screw and bolted. The material and thickness of the main frame portion 32 and the crushing portion 33 are the same as those of the main frame portion 12a and the crushing portion 12b of the first embodiment described above.

  In addition, an inner insertion hole 35a and an outer insertion hole 35b are vertically connected to an inner portion 34a and an outer portion 34b of an overlap portion 34 between the front portion of the main frame portion 32 and the rear end portion of the crushing portion 33 fitted therein. Each step is drilled.

  As shown in FIG. 7B, the inner insertion hole 35a and the outer insertion hole 35b are offset in the longitudinal direction of the vehicle body, and correspond to the inner insertion hole 35a and the outer insertion hole 35b on the inner surface of the crushing portion 12b. The weld nut 36 is welded to the position where

  When assembling, the rear end of the crushing portion 33 having the closed cross-sectional shape is fitted into the front end of the main frame portion 32 having the same closed cross-sectional shape, and the inner insertions formed respectively in the main frame portion 32 and the crushing portion 33 are inserted. The hole 35a and the outer insertion hole 35b are aligned. Then, a bolt 37 is inserted into the insertion holes 35a and 35b from the outside, and the bolt 37 is screwed into the weld nut 36 to fasten the main frame portion 32 and the crushing portion 33.

  At that time, since the bolt 37 inserted into the inner insertion hole 35a and the bolt 37 inserted into the outer insertion hole 35b are offset in the vehicle body front-rear direction, the overlap portion 34 connecting the both insertion holes 35a, 35b The outer peripheral surface is a taper-like coupling portion that recedes obliquely rearward from the inner side to the outer side in the vehicle body width direction. In addition, the front-end | tip of the front side frame 31 arrange | positioned at the vehicle width direction right and left is mutually connected by the cross member 13 (refer FIG. 1).

  In such a configuration, when the impact load F at the time of a frontal collision is input to the left and right front side frames 31 via the cross member 13, the crushing portion 33 is axially crushed in a bellows shape and the impact energy is absorbed. The If the impact energy cannot be sufficiently absorbed by only the axial crushing of the crushing portion 33, the impact load F is transmitted to the main frame portion 32 side via the bolt 37. Since the inner insertion hole 35a and the outer insertion hole 35b through which the bolt 37 is inserted are offset in the longitudinal direction of the vehicle body, the transmission distance of the impact load F is determined by the position of the bolt 37 inserted through the inner insertion hole 35a. The position of the bolt 37 inserted through the outer insertion hole 35b is shorter.

  Accordingly, the impact load F first reaches the bolt 37 inserted through the inner insertion hole 35a, and reaches the bolt 37 inserted through the outer insertion hole 35b with a certain delay.

  As a result, since the impact load F is input to the front end of the main frame portion 32 in an offset state, the input load is unbalanced inside and outside the main frame portion 32, and a bending moment is generated in the overlap portion 34. Then, the moment load due to this bending moment is concentrated in a relatively weak portion inside the main frame portion 32, and the middle of the main frame portion 32 is bent and deformed outward in the vehicle body width direction from that point. Impact energy is absorbed by bending deformation.

  Thus, in this embodiment, the crushing portion 33 is fitted into the main frame portion 32, and the overlap portion 34 is offset in the vehicle longitudinal direction with the bolts 37 on the inner 34a side and the bolts 37 on the outer 34b side. Since the impact load F reaching the outer 34b side is delayed by bolting and coupling, the offset amount between the inner insertion hole 35a and the outer insertion hole 35b is arbitrarily adjusted, so that the impact is reduced. A bending moment capable of efficiently absorbing energy can be selected relatively easily.

  8 and 9 show a fourth embodiment of the present invention. This embodiment is a modification of the first embodiment described above. In the front side frame 12 described in the first embodiment, the joint surface 12c is tapered so as to recede obliquely backward from the vehicle width direction inner side to the outer side. However, in this embodiment, the joint surface 12c is lowered in the vehicle body height direction. It is formed in a tapered shape that recedes obliquely backward from the side toward the upper side.

  By forming the joint surface 12c in a tapered shape that is inclined obliquely upward, the transmission distance of the impact load F to the main frame portion 32 is shorter on the lower side than on the upper side. Therefore, the impact load F first reaches the lower side of the main frame portion 32 and gradually reaches the upper joint surface 12c.

  As a result, since the impact load F is first input below the joint surface 12c of the main frame portion 12a, the input load becomes unbalanced above and below the main frame portion 12a, and a bending moment is generated in the main frame portion 12a. To do. Then, the moment load due to this bending moment is concentrated on a relatively weak portion in the middle of the lower side of the main frame portion 12a, and the middle portion of the main frame portion 12a is bent upward in the vehicle body height direction starting from this concentrated portion. The impact energy is absorbed by the bending deformation at this time, and the same effect as the first embodiment described above can be obtained.

  The present invention is not limited to the above-described embodiments. For example, when the mount bracket 20 is not fixed to the front side frame 12 and the region Z1 shown in FIG. 1 can be set as a crushable zone. The joint surface 12c (26d, 26e) is formed in the vicinity of the region Z1, or the overlap portion 34 is formed as in the third embodiment.

  Further, it goes without saying that the vehicle body support structure according to the present invention can be applied to a rear side frame provided at the rear portion of the vehicle body.

The schematic plan view which shows the vehicle body frame structure of the vehicle body front part by a 1st form Schematic side view showing the vehicle body frame structure at the front of the vehicle body Same part perspective view of front side frame FIG. 1 is a schematic plan view corresponding to FIG. 1 in a state where the crushing portion is axially crushed. FIG. 1 is a schematic plan view corresponding to FIG. 1 with the main frame portion bent and deformed. The 2nd form is shown, (a) is a principal part perspective view of the front side frame which shows the state where a crushing part is attached, (b) is a principal part perspective view of a front side frame. The third embodiment is shown, (a) is a perspective view of the main part of the front side frame, (b) is a horizontal sectional plan view by a cut surface passing through the insertion hole of (a). The schematic side view which shows the vehicle body frame structure of the vehicle body front part by a 4th form FIG. 8 is a schematic plan view corresponding to FIG. 8 with the main frame portion bent and deformed.

Explanation of symbols

11 ... Engine room
12, 26, 31 ... front side frame,
12a ... main frame part,
12b, 26c, 33 ... crushing part,
12c, 26d, 26e ... joint surfaces,
13: Cross member,
16: Suspension cross member,
19 ... Power unit,
20 ... Mount bracket,
26a ... Inner frame,
26b ... outer frame,
32 ... main frame part,
34. Overlap part,
35a ... inner insertion hole,
35b ... Outer insertion hole,
37 ... Bolt,
θ ... Inclination angle,
F: Impact load,
P ... starting point,
Y ... axis,
Z1, Z2 ... area (crushable zone)

Claims (5)

A pair of side frames extending in the front-rear direction of the vehicle body are provided on both sides in the vehicle body width direction, and the front ends of the side frames are connected via a cross member, and the ends of the side frames are axially crushed at the time of a collision. A vehicle body frame structure in which a first member for absorbing impact energy is provided, and a second member having a high cross-sectional strength is provided continuously to the first member.
A vehicle body frame structure characterized in that a connecting portion between the first member and the second member is inclined in a taper shape with respect to an axis perpendicular to the central axis in the vehicle width direction. 2. The vehicle body frame structure according to claim 1, wherein the joint portion is a joint surface formed of a tailored blank material. 2. The vehicle body frame structure according to claim 1, wherein the coupling portion is formed by fastening a flange formed on a joint surface between the first member and the second member. The vehicle body frame structure according to claim 1, wherein a part of an end portion of the second member is connected to the cross member, and the first member is joined to the end portion of the second member. 2. The vehicle body frame structure according to claim 1, wherein the coupling portion is formed by a bolt for fastening an overlap portion formed by fitting the first member and the second member.

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