JP2008056191A - Front structure of vehicle body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front structure of a vehicle body securing driveability and having superior impact energy absorbing performance. <P>SOLUTION: In the front structure of a vehicle body, an intermediate part of each of a right and a left side members 22 arranged under a right and a left side frames 2 extending in the back and forth direction of the vehicle body are connected to each other by a rear cross member 51, and a front and a rear ends of the side member 22 are connected to the right and the left side frames 2, and an intermediate support member 41 fixed to an intermediate fitting part 28 of each side member 22 comprises a sub frame 21 connected to an intermediate fitting part 5 of the side frame 2. The intermediate fitting part 5 of the side frame 21 and the intermediate support member 41 are connected to each other through a connecting means 16 to be released by the relative movement of the intermediate support member 41 in relation to the intermediate fitting part 5 of the side frame 2 with the movement of the rear cross member 51 due to the relative backward movement of a power unit P/U. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle body front structure in which a subframe is disposed below a side frame.

  There is a vehicle in which a sub-frame for supporting a suspension is arranged below left and right side frames extending in the front-rear direction of the vehicle body at the front of the vehicle body.

  As this type of sub-frame, for example, a side member that extends in the front-rear direction on the left and right sides of the vehicle body and a cross member that connects the front and rear portions of the left and right side members are formed. Each is fixed to the frame, and the intermediate portion is supported on the side frame via the intermediate connection bracket. Furthermore, a bead for bending is provided between the front end and the intermediate portion of the side member in a direction substantially perpendicular to the axial direction of the side member, and when a buckling load is applied at the time of collision, the bead for bending is used as a trigger. 2. Description of the Related Art An automobile subframe structure that deforms a side member is known (see, for example, Patent Document 1).

  In addition, the front and rear parts of the left and right side members extending in the front-rear direction are connected by cross members, and both front and rear ends of the side members are supported by the side frame via rubber bushes, and are erected in the middle part. A subframe is also known in which the intermediate support portion is supported by a side member via a rubber bush (see, for example, Patent Document 2).

JP-A-8-85473 Japanese Patent Laying-Open No. 2005-271810

  According to Patent Document 1, the front end and rear end of the side member that forms the subframe that supports the suspension are fixed to the side frame, and the intermediate portion is supported on the side frame via the intermediate connection bracket. The subframe and the side frame are firmly coupled to increase the rigidity of the side frame and the subframe, so that the suspension support rigidity and the vehicle body rigidity are improved, and the steering stability is improved. In addition, by providing a bead for bending in a direction substantially orthogonal to the axial direction of the side member between the front end portion and the intermediate portion of the side member, when the impact load is applied from the front during a collision, the bending bead provided on the side member is provided. The buckling deformation of the side member is induced by the bead portion.

  However, since the front end and rear end of the side member are fixed to the side frame and the intermediate portion is supported by the side frame via the intermediate connection bracket, the side frame and the sub frame are deformed by the impact load at the time of collision. There is a concern that this may restrain the impact energy absorption.

  That is, in the initial stage of the collision, a collision energy absorption characteristic is obtained by buckling deformation of the front portions of the side frame and the subframe. On the other hand, since the front and rear end portions and the intermediate portion of the side member over which the cross member is stretched are firmly coupled to the side frame, when the power unit such as an engine relatively moves backward and comes into contact with the cross member in the latter half of the collision In addition, the deformation of the subframe and the side member is restricted, and there is a possibility that good impact energy absorption due to the deformation of the subframe and the side member cannot be ensured.

  As a countermeasure against this, the side frame effective crushing stroke is suppressed by suppressing the rigidity of the rear part of the side frame at the rear part of the connecting part between the connecting part of the intermediate connecting bracket and the side frame, that is, the connecting part of the side frame with the intermediate connecting bracket. If this is ensured, there is a concern that the rigidity of the side frame is lowered, the vehicle body rigidity and the suspension support rigidity are lowered, and the steering stability is affected.

  In addition, the rigidity of the connecting portion of the intermediate portion of the side frame with the intermediate connecting bracket increases due to the connection of the intermediate connecting bracket, making it difficult to ensure a sufficient effective crushing stroke of the side frame.

  On the other hand, according to Patent Document 2, since the side member and the sub frame are connected via the rubber bush, the restraint of the side frame and the sub frame due to the impact load at the time of collision is relaxed. This improves the absorption of impact energy. However, there is a concern that the suspension support rigidity and the vehicle body rigidity may be reduced due to a decrease in the coupling rigidity between the side frame and the subframe, which may affect the steering stability.

  Accordingly, an object of the present invention made in view of such points is to provide a vehicle body front structure that ensures steering stability and is excellent in impact energy absorption.

  The invention of the vehicle body front part structure according to claim 1 that achieves the above object is provided below the side frames extending in the vehicle body front-rear direction, the front end portions of the left and right side members extending in the vehicle body front-rear direction, and An intermediate support member that couples the rear end portion to the left and right side frames and supports a cross member on an intermediate attachment portion formed in the middle in the front-rear direction of the side members is provided to the intermediate attachment portions of the left and right side frames. In a vehicle body front structure having a subframe to be coupled and a power unit mounted between the left and right side frames, buckling is caused by a collision load from the front between the intermediate mounting portion of the side member and the rear end side. The cross member has a bending promoting portion that is deformed, and the intermediate mounting portion and the intermediate support member of the side frame are moved by the rear movement of the power unit. Wherein the coupling by the relative movement of the intermediate support member relative to the intermediate attachment portion of the side frame is coupled via a coupling means to be released with.

  According to the present invention, the front end portion and the rear end portion of the side member are coupled to the side frame, and the cross member is coupled to the intermediate mounting portion of the side frame by the intermediate support member and the coupling means. The rigidity is improved and the suspension support rigidity and the vehicle body rigidity are ensured, and good steering stability is obtained.

  On the other hand, in the initial stage of the collision, the impact energy is absorbed and the impact load is reduced by the deformation of the front region in front of the intermediate mounting portion of the side frame and the side member connected by the intermediate support member and the coupling means. Further, in the latter half of the collision when the power unit moves backward, the cross member is moved backward by the backward movement of the power unit, and the coupling between the intermediate mounting portion of the side frame and the intermediate support member by the coupling means is released, and the cross member is moved from the side frame. The impact load is reduced by suppressing the drag against the backward movement of the power unit to ensure the absorbability of the impact energy, and the impact on the occupant is greatly reduced. Further, by forming a bending promoting portion that buckles and deforms due to an impact load from the front between the intermediate mounting portion and the rear end portion of the side member, the movement of the cross member due to the backward movement of the power unit in the late stage of the collision It is ensured, and effective impact energy absorption due to buckling deformation between the intermediate mounting portion and the rear end portion of the side member can be ensured.

  According to a second aspect of the present invention, in the front structure of the vehicle body of the first aspect, the buckling resistance against an impact load from the front is lower than the intermediate mounting portion and the rear portion of the front portion of the side member than the intermediate mounting portion. It is characterized by a large gap between the ends. According to the present invention, the front range of the side member is set to have a buckling resistance smaller than that of the rear range, and the impact energy is efficiently absorbed by the buckling of the front range in the initial stage of the collision.

  The invention according to claim 3 is the vehicle body front part structure according to claim 1, wherein the bending promoting portion is connected to the rear end side of the intermediate attachment portion of the side member via the bending portion and is moved rearward. A front part that gradually descends as it progresses, a middle part that continues to the rear end of the front part via a bent part and that extends substantially horizontally and rearwardly, and a bent part at the rear end of the middle part The front end is continuous and gradually rises as it moves rearward, and the rear end is continuously formed with the rear portion continuing to the rear end side.

  According to the present invention, the buckling promoting portion is buckled and deformed so that the inclination angle of the front portion and the rear portion is increased by the impact load from the front in the late stage of the collision, and the dropped power unit is guided downward, and the rear of the power unit The drag against the movement can be suppressed, and the influence on the passenger compartment due to the retreat of the power unit can be reduced.

  According to a fourth aspect of the present invention, in the vehicle body front structure according to any one of the first to third aspects, the coupling means includes a slit-shaped bolt mounting hole provided in the intermediate support member and having a front end opened. It is characterized by comprising: a formed bracket; and a mounting bolt that is fixed to the intermediate mounting portion of the side frame and that penetrates the bolt mounting hole and is coupled to the bracket so as to be relatively movable.

  According to this invention, due to the relative rearward movement of the intermediate support member with respect to the intermediate mounting portion of the side frame, the bracket moves rearward and the bolt mounting hole is disengaged from the mounting bolt fixed to the side frame. The connection with the side frame can be released.

  The invention according to claim 5 is the vehicle body front part structure according to any one of claims 1 to 4, further comprising a reinforcing member that reinforces a space between the intermediate mounting portion and the rear end portion of the side frame. Features.

  According to the present invention, the rigidity of the side frame is ensured while securing the impact energy absorption characteristics by reinforcing the space between the intermediate mounting portion and the rear end portion of the side frame that has little influence on the impact energy absorption at the time of collision by the reinforcing member. As a result, the suspension support rigidity and the vehicle body rigidity are ensured, and good steering stability is obtained.

  According to the present invention, the rigidity of the side frame and the sub frame is improved, the suspension support rigidity and the vehicle body rigidity are ensured, and good steering stability is obtained.

  On the other hand, at the initial stage of the collision, the impact energy is reduced by the deformation of the front range ahead of the intermediate mounting portion of the side frame and the side member connected by the intermediate support member and the coupling means to reduce the collision load and the power unit moves backward. In the late stage of the collision, the coupling between the intermediate mounting portion of the side frame and the intermediate support member support member by the coupling means is released, and the resistance against the backward movement of the power unit is suppressed to ensure the shock energy absorption. Reduce the load and greatly reduce the impact on the occupant.

Embodiments of a vehicle body front structure according to the present invention will be described below with reference to FIGS. In each figure, an arrow F indicates the vehicle body front direction.
FIG. 1 is a perspective view showing an outline of the vehicle body front portion 1 in the vehicle body front portion structure according to the present embodiment, and FIG. 2 is a side view schematically showing the vehicle body from the direction of arrow A in FIG.

  As shown in FIG. 1, left and right side frames 2 formed in a hollow cross-sectional shape extending in the longitudinal direction of the vehicle body are disposed in the vehicle body front portion 1.

  The side frame 2 is substantially horizontal and has a straight line extending in the front-rear direction. The front part 3 is formed on the lower surface of the front end and the intermediate part 5 is formed on the lower surface of the rear end. A kick-up portion 7 that is continuous with the rear end and is gradually inclined downward as it moves rearward, and a rear end portion 8 that is continuously formed at the rear end of the kick-up portion 7 and connected to a floor frame (not shown). The rear region 6 is formed continuously. The front mounting portion 4 is provided with a front support member 40 extending downward.

  A bumper frame 11 extending in the vehicle width direction is suspended over the front ends of the left and right side frames 2 via a bracket 10. An impact buffer member made of polypropylene foam material (not shown) is disposed on the front surface of the bumper frame 11, and an outer surface of the impact buffer member is covered with a resin bumper face to form a bumper extending in the vehicle width direction. ing. An engine room E is formed between the left and right side frames 2, and a power unit P / U including an engine and a transmission is mounted in the engine room E.

  A floor panel (not shown) is provided so as to cover the left and right floor frames from above, and the vicinity of the front end portion of the floor panel is extended upward along the kick-up portion 7 of the side frame 2 and is formed at the front end portion. A bulkhead portion that extends upward and separates the engine room E and the vehicle compartment R is formed.

  Below the left and right side frames 2, a pair of left and right side members 22 extending in the front-rear direction with a hollow cross-sectional shape and between the front end portions of the left and right side members 22 extending in the vehicle width direction are spanned. A sub-frame 21 having a front cross member 35 that is fixed in this manner and a rear cross member 51 that is fixed in a vehicle width direction between intermediate portions in the front-rear direction is disposed. The rear cross member 51 will be described later.

  Each side member 22 extends in the front-rear direction, has a front end mounting portion 24 formed on the upper surface of the front end, and an intermediate mounting portion on the upper surface of the rear end via a first bend promoting portion 25 extending rearward from the front end mounting portion 24. A front range 23 where 28 is formed, a second bend promoting portion 30 continuous with the rear end of the front range 23, and a rear range 29 where a rear end 34 is formed at the rear end of the second bend promoting portion 30. Are continuously formed.

  The first bend promoting portion 25 has an inclined portion 26 that is continuous with the front end of the intermediate attachment portion 28 via the bent portion and is inclined so as to gradually rise as it moves forward, and is attached to the upper surface of the front end of the inclined portion 26. A portion 24 is formed.

  The second bending promoting portion 30 includes a front portion 31, an intermediate portion 32, and a rear portion 33. The front portion 31 has a front end continuous to the rear end side of the intermediate mounting portion 28 via a bent portion and moves rearward. The intermediate portion 32 is inclined so as to descend gradually, and the intermediate portion 32 continues to the rear end of the front portion 31 via a bent portion and extends substantially rearwardly while the rear portion 33 is rearward of the intermediate portion 32. In addition, the front end is continuous through the bent portion and is inclined so as to gradually rise as it moves rearward, and the rear end is formed in a bent shape that continues to the front end of the rear end portion 34 through the bent portion. With the first buckling promoting portion 25 and the second buckling promoting portion 30, the side member 22 has a buckling resistance against an impact load from the front, the rear range 29 and the front range 23 ahead of the intermediate mounting portion 28. Specifically, a large gap is set between the intermediate mounting portion 25 and the rear end portion 34.

  A phosphorus hose 37 extending in the vehicle width direction is stretched over the front ends of the left and right side members 22 via a bracket 36. An impact cushioning member formed of a polypropylene foam material (not shown) or the like is disposed on the front surface of the phosphorus hose 37, and the outer surface of the impact cushioning member is covered with a bumper face. Further, the phosphorus hose 37 is set so as to be positioned substantially immediately below the bumper frame 11 described above.

  The sub-frame 21 configured in this way has a front end mounting portion 24 formed on the front end upper surface of the left and right side members 22 at the lower end of the front support member 40 provided on the front mounting portion 4 of the side frame 2. The rear end portion 34 that is joined and formed at the rear end is firmly fixed to the rear end portion 8 of the side frame 2 by a plurality of, for example, three bolts to ensure high load transmission efficiency between the side frame and the subframe 21. ing. Further, the intermediate attachment portion 28 of the side member 22 is coupled and attached to the intermediate attachment portion 5 of the side frame 2 via the intermediate support portion 41 and the coupling means 61 formed integrally with the rear cross member 51. The coupling rigidity by the bolt between the lower end of the front support member 40 and the front end mounting portion 24 of the side member 22 is set to be relatively low.

  Next, the rear cross member 51 and the coupling means 61 will be described with reference to FIGS. 3 to 5 together with FIGS. 3 is an exploded perspective view of the main part of the coupling means 61, FIG. 4 is a sectional view taken along the line II of FIG. 3 in the coupled state, and FIG. 5 is an operation explanatory diagram when the collision load of the coupling means 61 acts.

  As shown in FIG. 1, both ends of the cross member 51 include a front face 42 and a rear face 43 that extend in the vehicle width direction and face each other, a lower face 44 that connects lower edges of the front face 42 and the rear face 43, and a front face 42 and a rear face. 43 having a substantially rectangular cross-sectional shape extending in the vehicle width direction and having an upper surface 45 connecting each upper edge of 43, and the lower surface 44 is firmly welded to the intermediate mounting portion 28 formed on the side member 22. Yes. Further, a suspension support bracket 46 having an inverted U-shaped cross section with the lower portion opened on the upper surface 45 is provided, and a suspension member, for example, a suspension lower arm (not shown) is attached to and supported by the suspension support bracket 46.

  A rear cross member 51 extending in the vehicle width direction is spanned between the left and right intermediate support members 41, and each end is welded to the intermediate support member 41. The rear cross member 51 has a front surface 53 and a rear surface 54 bent downward along the front and rear edges of the upper surface 52 extending in the vehicle width direction, and the lower portion extending in the vehicle width direction is open. The cross section is formed in an inverted U shape. The rear cross member 51 is disposed so as to face a part of a power unit P / U having a front surface 53 mounted in the engine room E, for example, the rear part of the engine, and the power unit P is connected to the rear cross member 51 via an engine mount or the like. / U is installed.

  The coupling means 61 includes a coupling member 62 that is attached to the upper surface 45 of the intermediate support member 41 as shown in an exploded perspective view of a main part in FIGS. 1, 3, and 4, and an intermediate mounting portion between the coupling member 62 and the side frame 2. 5 and a pair of bolt mounting holes 70c, 70d formed in the intermediate mounting portion 5 of the side frame 2 and welded to the intermediate mounting portion 5, respectively. Nuts 71c and 71d serving as bolt fixing means and a pair of mounting bolts 72 and 73 are provided.

  As shown in FIGS. 3 and 4, the coupling member 62 includes a rectangular plate-like base 63 that is placed on and coupled to the upper surface 45 of the intermediate support member 41, and the longitudinal direction of the base 63 extends along the outer side in the vehicle width direction. A pair of bolt insertion holes 63c and 63d are formed in the first and second holes.

  On the base 63, the base 63 is substantially covered, and the bolt insertion holes 63c and 63d are covered with a gap on the outer side in the vehicle width direction so as to be continuous in the front-rear direction with an inverted U-shaped section or semicircular arc shape. A bracket 64 formed with a first coupling portion 65 that is raised and opened on the front edge 65a side is welded. Bolt mounting holes 65c and bolt insertion holes 65d are opened at the front and rear portions of the first coupling portion 65, respectively. In particular, the bolt mounting hole 65c is formed in a U-shaped slit shape that is long in the front direction and has a front end opened to the front edge 65a.

  Further, on the rear part of the first coupling part 65, the bolt insertion hole 65d is continuous in the front-rear direction with an inverted U-shaped or semicircular cross-section so as to cover the bolt insertion hole 65d with a gap, and both side edges and rear edges are the first coupling. A second coupling portion 66 that is welded and coupled to the portion 65 and that is open on the front edge 66a side that is the front side is provided. A bolt mounting hole 66 d is opened in the second coupling portion 66. The bolt mounting hole 66d is formed in a U-shaped slit shape that is long in the front direction and has a front end opened to the front edge 66a.

  The spacer 67 has an inverted U-shaped cross section or a semicircular arc shape, and is continuously connected in the front-rear direction, and is fitted to the upper surface of the first coupling portion 65, and a rear edge of the first lower surface 67a via a stepped portion. A second lower surface 67b that is continuously U-shaped or semicircular in cross-section and is continuously fitted in the front-rear direction on the upper surface of the second coupling portion 66, and an upper surface 67c that is in contact with the intermediate mounting portion 7 of the side frame 2. It is formed in a block shape. The spacer 67 has bolt through holes 68c and 68d penetrating the first lower surface 67a and the upper surface 67c and the second lower surface 67b and the upper surface 67c.

  A reference for extending the bolt insertion hole 63c of the base 63, the bolt mounting hole 65c of the first coupling portion 65, the bolt through hole 68c of the spacer 67, the bolt mounting hole 70c and the nut 71c formed in the side frame 2 in the vertical direction. Arranged on the line c.

  Similarly, the bolt insertion hole 63d of the base 63, the bolt insertion hole 65d of the first coupling portion 65, the bolt mounting hole 66d of the second coupling portion 66, the bolt through hole 68d of the spacer 67, the bolt mounting hole 70d of the side frame 2, and the nut. 71d is arrange | positioned on the reference line d extended in the up-down direction behind the reference line c.

  The bolt insertion hole 63c of the base 63 has a diameter larger than the diameter of the head 72a of the mounting bolt 72, while the bolt mounting hole 65c of the first coupling portion 65 is larger than the diameter of the shaft portion 72b and larger than the diameter of the head 72a. It is set to a small diameter. Similarly, the bolt insertion hole 63d of the base 63 and the bolt insertion hole 65d of the first coupling portion 65 have a diameter larger than the diameter of the head 73a of the mounting bolt 73, while the bolt mounting hole 66d of the second coupling portion 66 is a shaft portion. The diameter is set larger than the diameter of 73b and smaller than the diameter of the head 73a.

  Then, the mounting bolt 72 is inserted from the bolt insertion hole 63c of the base 63, and passes through the bolt mounting hole 65c of the first coupling portion 65, the bolt through hole 68c of the spacer 67, and the bolt mounting hole 70c of the side frame 2, and the nut. The first coupling portion 65 and the intermediate mounting portion 5 of the side frame 2 are fastened with the mounting bolt 72 and the nut 71c through the spacer 67 by screwing to the 71c with a preset fastening torque. Similarly, the mounting bolt 73 is inserted from the bolt insertion hole 63d of the base 63, the bolt insertion hole 65d of the first coupling portion 65, the bolt mounting hole 66d of the second coupling portion 66, the bolt through hole 68d of the spacer 67, and the side frame. The second coupling portion 66 and the side frame 2 are interposed between the mounting bolt 73 and the nut 71d through the spacer 67 by passing through the second bolt mounting hole 70d and screwing into the nut 71d with a predetermined fastening torque. The attachment part 5 is fastened.

  In this coupled state, as shown in FIG. 5, the shaft portion 72 b of the mounting bolt 72 is positioned on the reference line c near the rear end of the bolt mounting hole 65 c formed in the first coupling portion 65, and The shaft portion 73b is located on the reference line d near the rear end of the bolt attachment hole 66d of the second coupling portion 66.

  Thus, the intermediate support member 41 welded to the intermediate attachment portion 28 of the side member 22 and the intermediate attachment portion 5 of the side frame 2 are connected via the connecting means 61.

  On the other hand, when the intermediate support member 41 coupled to the intermediate mounting portion 28 of the side member 22 moves relative to the intermediate mounting portion 5 of the side frame 2 relative to the rear of the vehicle body with a predetermined load or more, the intermediate support member 5, the connecting member 62 moves rearward along the first lower surface 67a and the second lower surface 67b of the spacer 67 from the state indicated by the solid line in FIG. The bolt mounting hole 65c of the slit-like first coupling part 65 and the bolt mounting hole 66d of the second coupling part 66 are disengaged from the mounting bolts 72 and 73 supported by the side frame 2, and the intermediate support member 41 and the side The connection with the frame 2 is released.

  In this way, the intermediate mounting portion 5 of the side frame 2 is coupled to the intermediate support member 41 so as to be relatively movable by the movement load set in advance by the coupling means 61, so that the intermediate mounting formed at the rear portion of the front range 3. The rigidity of the portion 5 is not increased by the coupling with the intermediate support member 41, and the effective crushing stroke in the front range 3 can be ensured over the entire length of the front range 3. As the effective crushing stroke in the front area 3 increases, the collision resistance in the front area 3 at the time of collision can be increased.

  Next, the operation of the vehicle body front part structure including the side frame 2 and the subframe 21 configured as described above is shown in FIG. 1, FIG. 6 showing an outline at the time of collision, and “impact drag-impact stroke correlation diagram” accompanying the collision. This will be described with reference to FIG.

  The left and right side members 22 are firmly coupled to each other by the rear cross member 51 and the intermediate support member 41 to ensure the rigidity of the subframe 21, and the front end mounting portion 24 of the side member 22 of the subframe 21 in which this rigidity is ensured is the front. It connects with the front mounting part 4 of the side frame 2 via the part support member 40, and the rear end part 34 is coupled to the rear end part 8 of the side frame 2, and the intermediate mounting part 28 is coupled to the intermediate support member 41. By coupling to the intermediate mounting portion 5 of the side frame 2 by the means 61, the sub frame 2 and the side frame 21 are firmly coupled to increase the rigidity of the side frame 2 and the sub frame 21, and the suspension support rigidity and the vehicle body rigidity are increased. This ensures good steering stability during normal driving.

  On the other hand, when the vehicle collides forward with an obstacle, the collision load P from the obstacle is distributed and input to the bumper frame 11 provided at the front end of the side frame 2 and the phosphorus hose 37 provided at the front end of the subframe 21. If the collision is mild, the impact energy can be absorbed by the deformation of the brackets 10 and 36, and the subsequent repair can be performed only by exchanging the brackets 10 and 36.

  However, when the degree of collision is large, the impact load P1 that is not absorbed by the bumper frame 11 and the bracket 10 as shown in FIG. 6B is rearward from the front end of the side frame 2 substantially along the front-rear direction. It is input toward. On the other hand, the impact load P2 that has not been absorbed by the phosphorus hose 37 and the bracket 36 is input rearward along the substantially front-rear direction from the front end of the subframe 21, particularly the side member 22.

  At the initial stage of the collision, as shown in FIG. 6 (b), with respect to the rear range 6 of the side frame 2 whose rigidity is secured by the construction of the intermediate support member 41 by the impact load P1 input from the front end of the side frame 2. The impact energy of the impact load P1 is absorbed and the impact load P1 is reduced by the crushing deformation in which the front range 3 having a relatively low rigidity is crushed sequentially from the front end to the rear side along the axial direction. On the other hand, in the subframe 21, the inclined portion 26 of the first bending promoting portion 25 is pushed down due to the inclination by the impact load P2 input from the front end of the side member 22, and the impact load is mainly caused by buckling deformation. The impact energy of P2 is absorbed and the impact load P2 is reduced.

  At the initial stage of the collision, as shown in FIG. 7, the impact resistance of the side frame 2 and the subframe 21 is suddenly increased by the impact load P1 from the obstacle due to the collision with the obstacle, and the increased impact resistance is It decreases sequentially as the crushing deformation collapses from the front in the front region 3 of the frame 2 and the buckling deformation of the first bending promoting portion 25 of the subframe 22.

  Here, since the rigidity of the rear region 6 of the side frame 2 is ensured, the impact energy of the impact load P1 is absorbed by the crushing deformation in which only the front region 3 is crushed, and the impact load P1 is reduced. Similarly, since the rigidity of the rear region 26 of the side member 21 is ensured, the impact energy of the impact load P2 is absorbed by the buckling deformation of only the front region 23, and the impact load P2 is reduced.

  In particular, as the effective crushing stroke in the front region 3 of the side frame 2 increases, the impact resistance against the impact load P1 in the initial stage of the collision is ensured, and the impact energy absorption efficiency is improved. In addition, since impact resistance that increases relatively rapidly in the initial stage, that is, vehicle body acceleration, is generated, it becomes possible to restrain the occupant by operating the airbag system and the seat belt system at an early stage, thereby reducing the obstacle value of the occupant. be able to.

  Further, the impact degree is large and the crushing deformation in the front region 3 of the side frame 2 and the buckling deformation of the first bending promoting portion 25 of the side member 21 do not absorb the impact energy, and accompanying the crushing deformation in front of the vehicle body. In the latter half of the collision when the collision load acts on the power unit P / U and the power unit P / U moves relatively rearward, the power unit P / U moving rearward contacts the rear cross member 51 or mounts the engine mount. A load directed rearward is transmitted to the rear cross member 51, and the rear cross member 51 moves rearward together with the power unit P / U. As the rear cross member 51 moves rearward, the intermediate support member 41 integrally coupled with the rear cross member 51 has the front portion 32 and the rear portion so that the bending promoting portion 30 of the rear region 29 of the side member 22 is indicated by a virtual line 30a. It moves slightly rearward relative to the intermediate mounting portion 5 of the side frame 2 while being buckled and deformed so that the inclination angle of 34 increases.

  When the intermediate support member 41 moves rearward relative to the intermediate mounting portion 5 of the side frame 2, the coupling member 62 attached to the intermediate support member 41 is moved from the state shown by the solid line in FIG. The first coupling portion 65 and the second coupling portion 66 of the coupling member 62 move relatively rearward along the first lower surface 67a and the second lower surface 67b of the first and second coupling portions 65 and 66. The slit-shaped bolt mounting holes 65c and 66d thus detached from the shaft portions 72b and 73b of the mounting bolts 72 and 73 supported by screwing the nuts 71c and 71d into the intermediate mounting portion 5 of the side frame 2, respectively.

  By this separation, the deformation restraint of the subframe 21 by the side frame 2 is released, and the second bending of the subframe 21 via the intermediate support member 41 by the rearward movement of the rear cross member 51 accompanying the rearward movement of the power unit P / U. The promotion portion 30 is further buckled and absorbs impact energy.

  Here, in the latter half of the collision, the power unit P / U moving backward releases the coupling of the side frame 2 and the subframe 21 by the intermediate support member 41 and the coupling means 61, and the power unit P / U moves backward by the subframe 2. The resistance against is greatly reduced. The absorption of the impact energy of the impact load by the power unit P / U moving rearward is absorbed mainly by the buckling deformation of the second bending promoting portion 30 formed in the rear region 29 of the subframe 22 of the side frame 21. Since the load is reduced, the impact drag against the impact load P in the latter half of the collision is suppressed, and the collision stroke is increased. In addition, the second bending promoting portion 30 is buckled and deformed so that the inclination angle of the front portion 31 and the rear portion 33 is increased by an impact load from the front, so that the dropped power unit P / U is positively moved downward. By being guided, the drag force against the backward movement of the power unit P / U can be suppressed, and the influence on the passenger compartment R due to the backward movement of the power unit P / U can be reduced.

  Therefore, according to the present embodiment, during normal running, the front end mounting portion 24 of the side member 22 of the subframe 21 is connected to the front mounting portion 4 of the side frame 2 via the front support member 40, and the rear The end coupling portion 34 is coupled to the rear end portion 9 of the side frame 2, and the intermediate mounting portion 28 is coupled to the intermediate mounting portion 5 of the side frame 2 by the intermediate support member 41 and the coupling means 61. The front and rear end portions and the intermediate portion are firmly coupled to the side frame 21 to secure the rigidity of the side frame 2 and the sub frame 21 to ensure the suspension support rigidity and the vehicle body rigidity, thereby obtaining good steering stability.

  In the initial stage of the collision, the deformation of the front part range 3 of the side member 2 and the front part range 23 of the side member 22 of the subframe 21 absorbs impact energy to reduce the impact load, and the power unit P / U moves backward. In the latter half of the collision, deformation of the rear portion 29 of the side member 22 absorbs impact energy and reduces the impact load. Therefore, the rear portion 6 of the side frame 2 is reinforced without considering the impact energy absorbing function at the time of collision. It becomes possible to ensure sufficient rigidity by the member, shape, plate thickness, etc., it becomes easy to ensure required suspension support rigidity and vehicle body rigidity, and it is possible to ensure excellent steering stability.

  On the other hand, when the vehicle collides forward with an obstacle, the impact energy of the impact load is absorbed by the deformation of the front range 3 of the side frame 2 and the front range 23 of the side member 21 where the buckling stroke is secured. As a result, the collision resistance against the impact load at the initial stage of the collision is increased, the impact energy absorption efficiency is improved, and in the latter half of the collision when the power unit P / U moves backward, the side by the intermediate support member 41 by the coupling means 61 Since the coupling between the frame 2 and the subframe 21 is released and the impact energy is reduced mainly by the deformation of the rear region 29 of the subframe 21 to reduce the impact load, the collision drag against the impact load in the late stage of the collision is suppressed. This greatly reduces the impact on the passenger.

  Further, by dividing the side frame 2 into a front range 3 which is a range of buckling deformation accompanying a collision and a rear range 6 which is a range where rigidity can be secured without considering the deformation accompanying the collision, The rigidity of the front range 3 and the rear range 6 can be set according to the performance, and the efficiency of the vehicle body design can be obtained.

  As a reference example to be compared with the present embodiment, the intermediate mounting portion 28 of the side member 22 of the subframe 21 and the intermediate mounting portion 5 of the side frame 2 in the present embodiment are firmly fastened via the intermediate support member 41. The operation will be described with reference to FIG.

  8A, the front end of the side member 22 of the sub-frame 21 is connected to the front end of the side frame 2 via the front support member 40, and the rear end 34 is coupled to the rear end 9 of the side frame 2. In addition, the intermediate mounting portion 5 is firmly coupled to the side frame 2 by the intermediate support member 41. However, the range of the intermediate mounting portion 5 of the side frame 2 is increased in rigidity by the intermediate mounting member 41 that is firmly coupled, and the effective crushing stroke in the front range 3 is set shorter than the effective crushing stroke in the present embodiment. The That is, the collision drag in the front range 3 is set smaller than the collision drag in the present embodiment.

  In the initial stage of the collision, as shown in FIG. 8B, the impact load P from the obstacle is distributed and inputted to the front ends of the side frame 2 and the subframe 21, and the side frame 2 is received by the impact load P1 inputted to the side frame 2. While the front range 3 of FIG. 2 is crushed in order from the front end to the rear side, the impact energy of the collision load P1 is absorbed and the impact load P1 is reduced, while the first load due to the impact load P2 input from the front end of the side member 22 The buckling deformation of the bent portion 25 absorbs the impact energy of the impact load P2 and reduces the impact load P2.

  In the initial stage of the collision, as shown by a broken line in FIG. 7, the collision drag between the side frame 2 and the subframe 21 suddenly increases due to the collision load P1 from the obstacle due to the collision with the obstacle. The deformation gradually decreases due to the crushing deformation that collapses from the front in the front region 3 of the side frame 2 and the buckling deformation of the first bending promoting portion 25 of the subframe 22.

  Here, the rigidity of the rear region 6 of the side frame 2 and the rear region 26 of the side member 21 is ensured, and the impact energy of the impact loads P1 and P2 is absorbed by the deformation of only the front regions 3 and 23, respectively. Reduce P1 and P2. Since the collision drag of the side frame 2 is set to be smaller than that of the present embodiment at the initial stage of the collision, the impact energy absorption efficiency is lower than that of the present embodiment.

  Further, in the latter half of the collision in which the power unit P / U moves backward, when the rearward moving power unit P / U contacts the rear cross member 51, the rear cross member 51 passes through the intermediate support member 41 and the side frame 2 Therefore, the power unit P / U is prevented from retreating, and as shown in FIG. 7, the collision resistance increases rapidly as compared with the present embodiment, and the collision resistance is large and the impact stroke is short. The impact on the occupant increases.

  As a countermeasure, if the rigidity of the rear region 6 in the side frame 2 is set low to secure the effective crushing stroke of the side frame 2, the rigidity of the side frame 2 is lowered and the rigidity of the vehicle body and the suspension support are lowered, thereby affecting the steering stability. There is a concern that

  Therefore, according to the present embodiment, when the intermediate support member 41 is moved relative to the intermediate mounting portion 5 of the side frame 2 relative to the rear of the vehicle body with a load greater than a preset value, the connection is released by the connecting means 61 that is released. By connecting the support member 41 and the intermediate mounting portion 5 of the side frame 2, the sub frame 21 and the side frame 2 are connected to each other and the rigidity of the side frame 2 and the sub frame 21 is ensured during normal running. Support rigidity and vehicle body rigidity are ensured, and good steering stability is obtained. On the other hand, when the vehicle collides forward with an obstacle, the impact energy absorption efficiency of the impact load due to the deformation of the front regions 3 and 23 of the side frame 2 and the side member 21 is improved, and the power unit P / U is moved backward. In the late stage of the collision, the coupling between the side frame 2 and the sub-frame 21 by the intermediate support member 41 is released to suppress the collision drag against the impact load, and the impact on the occupant is greatly relieved.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in the above-described embodiment, the coupling means 61 for coupling the intermediate support member 41 and the intermediate mounting portion 5 of the side frame 2 is a bracket in which bolt mounting holes 65c and 66d are formed on the intermediate support member 41 side with the front side open. 64, and fixing bolts 72 and 73 inserted into the bolt mounting holes 65c and 66d are fixed to the side frame 2, but a slit-shaped bolt mounting hole having a rear end opened on the side of the intermediate mounting portion 5 of the side frame 2 is provided. The formed bracket can be attached, and an attachment bolt inserted into the bolt attachment hole can be fixed to the intermediate support member 41 side. Further, the intermediate mounting portion 5 and the intermediate support member 41 of the side frame 2 are broken when the intermediate support member 41 is moved relative to the intermediate mounting portion 5 of the side frame 2 to the rear of the vehicle body with a load greater than a preset value. The connecting means 61 can also be constituted by bolts or the like.

1 is a perspective view of a vehicle body front portion showing an outline of a vehicle body front portion structure according to an embodiment of the present invention. It is the side view shown typically seen from the arrow A direction of FIG. It is a principal part disassembled perspective view of a coupling means. It is the II sectional view taken on the line of FIG. 3 in a coupling | bonding state. It is operation | movement explanatory drawing of a coupling | bonding means. It is a figure which shows the outline | summary at the time of a collision. It is an impact drag-impact stroke correlation diagram. It is a figure which shows the outline | summary at the time of the collision in a reference example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle body front part 2 Side frame 3 Front part range 4 Front part attachment part 5 Middle attachment part 6 Rear part part 8 Rear end part 21 Subframe 22 Side member 23 Front part range 24 Front end attachment part 25 First bending promotion part 28 Intermediate attachment Part 29 rear part 30 second bending promoting part 31 front part 32 intermediate part 33 rear part 34 rear end part 40 front support member 41 intermediate support member 51 rear cross member 61 connecting means 62 connecting member 64 bracket 65 first connecting part 65c Bolt mounting hole 66 Second coupling portion 66d Bolt mounting holes 72, 73 Mounting bolt P / U Power unit

Claims (5)

A front end portion and a rear end portion of the left and right side members extending in the longitudinal direction of the vehicle body are coupled to the left and right side frames, respectively, and are disposed below the side frames extending in the longitudinal direction of the vehicle body. An intermediate support member that supports a cross member is provided at an intermediate attachment portion formed in the middle in the front-rear direction of the left and right side frames, and includes a subframe coupled to the intermediate attachment portion of the left and right side frames, and a power unit is mounted between the left and right side frames. In the vehicle body front structure
Between the intermediate mounting portion and the rear end portion of the side member, there is a bending promoting portion that buckles and deforms due to a collision load from the front, and the intermediate mounting portion and the intermediate support member of the side frame are connected to the power unit. A vehicle body front structure, which is coupled through coupling means that is decoupled by the relative movement of the intermediate support member with respect to the intermediate mounting portion of the side frame accompanying the movement of the cross member due to the backward movement.   2. The buckling resistance against an impact load from the front is large between the intermediate mounting portion and the rear end portion with respect to a front portion range ahead of the intermediate mounting portion of the side member. Vehicle body front structure as described.   The bending promoting portion includes a front portion that continues to the rear end side of the intermediate attachment portion of the side member via the bending portion and gradually descends as it moves rearward, and a bending portion at the rear end of the front portion. An intermediate portion that is substantially horizontal and extends rearward through the front end, and the rear end of the intermediate portion continues to the rear end via a bent portion and rises gradually as it moves rearward. The vehicle body front part structure according to claim 1, wherein a rear part continuous with the part side is continuously formed. The coupling means is:
A bracket provided with a slit-like bolt mounting hole provided on the intermediate support member and having a front end opened;
4. A mounting bolt fixed to an intermediate mounting portion of the side frame and penetrating through the bolt mounting hole and coupled to the bracket so as to be movable relative to the bracket. Vehicle body front structure described in 2. The vehicle body front part structure according to any one of claims 1 to 4, further comprising a reinforcing member that reinforces a space between the intermediate mounting portion and the rear end portion of the side frame.

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