Vehicle-body structure of vehicle

At an upper part of a center pillar, a length L1 of a covering portion of a pillar inner panel is set to be substantially equal to a distance L2 between a pair of flange-ridgeline portions of a pillar reinforcement. Meanwhile, at a lower part of the center pillar, a length L3 of a covering portion of the pillar inner panel is set to be longer than a distance L4 between a pair of flange-ridgeline portions of the pillar reinforcement. Accordingly, a vehicle-body structure of a vehicle which can secure the proper absorption function of the vehicle collision load with cooperation of the first and second members can be provided.

BACKGROUND OF THE INVENTION

The present invention relates to a vehicle-body structure equipped with a closed cross section which is formed by a first member having a U-shaped cross section and a second member which is joined to a pair of flanges of the first member at both end portions thereof and extends in a longitudinal direction thereof.

Conventionally, a structure for restraining improper deformation of a center pillar has been developed in order to secure the safety of passengers in a vehicle side collision. Japanese Patent Laid-Open Publication No. 2004-130826, for example, discloses a structure in which a weak portion is provided at a lower potion of a center pillar, whereas a full-section-plastic-moment step portion where the full section plastic moment having its center in the vehicle longitudinal direction is discontinuous is provided at an upper portion of the center pillar. Herein, a value of the full section plastic moment of a lower side of the center pillar below the full-section-plastic-moment step portion is set to be higher than a full-section-plastic-moment straight line which connects a full-section-plastic-moment value of an upper end portion of the center pillar and a full-section-plastic-moment value of a middle portion of the center pillar.

Specifically, in this structure, in addition to a normal pillar reinforcement provided between a pillar outer panel and a pillar inner panel, there is provided a second pillar reinforcement which is located over a range from the above-described moment step portion to the middle portion of the center pillar. The moment step portion is formed by a portion which corresponds to an upper end portion of this second pillar reinforcement.

According to the structure disclosed in the above-described patent publication, in the vehicle collision, both the above-described moment step portion positioned at the upper portion of the center pillar and the above-described weak portion cause bending of the center pillar, so that it can be prevented that the center pillar bends greatly at its middle portion in the vehicle vertical direction. Thereby, the bent center pillar can be properly restrained from coming into the inside of a vehicle compartment.

Meanwhile, a vehicle-body structure, such as the above-described center pillar, is equipped with a closed cross section which is formed by a first member having a U-shaped cross section and a second member which is joined to a pair of flanges of the first member at both end portions thereof and extends in its longitudinal direction.

The inventors of the present invention conducted bending analyses, in developing an appropriate vehicle-body structure which can secure the passenger's safety in the vehicle collision, for the vehicle-body structure which is equipped with the closed cross section formed by the above-described first and second members and has some portion to promote the deformation as disclosed in the above-described patent publication. Consequently, it was found that there is a concern in some cases that the first and second members joined together may be removed (detached) from each other, so that the absorption function of a vehicle-collision load with cooperation of the first and second members may deteriorate improperly.

SUMMARY OF THE INVENTION

The present invention has been devised in view of the above-described concern, and an object of the present invention is to provide a vehicle-body structure of a vehicle which can secure the proper absorption function of the vehicle collision load with cooperation of the first and second members.

According to the present invention, there is provided a vehicle-body structure of a vehicle, comprising a first member having a U-shaped cross section with an open portion at one side thereof, the first member including a pair of flanges at both ends thereof and a pair of flange-ridgeline portions which is formed at respective inside ends of the pair of flanges, and a second member joined to the pair of flanges of the first member at both end portions thereof so as to cover the open portion of the first member, wherein the vehicle-body structure has a closed cross section which is formed by the first and second members and extends in a longitudinal direction thereof, the vehicle-body structure comprises at least two parts which are formed at different positions in the longitudinal direction of the vehicle-body structure, and the first and second members of the vehicle-body structure are configured to have respective shapes in a plane which is perpendicular to the longitudinal direction of the vehicle-body structure such that, at one of the two parts of the vehicle-body structure, a distance between the pair of flange-ridgeline portions of the first member is substantially equal to a length of the second member from an inside end of one of the both end portions to an inside end of the other of the both end portions, whereas, at the above-described other of the two parts of the vehicle-body structure, a length of the second member from the inside end of one of the both end portions to the inside end of the other of the both end portions is longer than a distance between the pair of flange-ridgeline portions of the first member.

Herein, the inventors found through the analyses that a specified part of the vehicle-body structure of the above-described patent publication set to promote its bending received a greater shearing load (force) than the other part during a collision-load input. Moreover, they found that decreasing this shearing load (force) could restrain the above-described improper detachment of the first and second members, thereby improving the absorption function of the collision load with cooperation of the first and second members.

Therefore, according to the present invention described above, since the second member has its length longer than the distance between the pair of flange-ridgeline portions of the first member, a part of the second member which covers the open portion of the first member can be deformed properly in accordance with deformation of the flange flange-ridgeline portions of the first member when the vehicle-body structure receives the collision load. Thereby, the shearing load acting on a joint portion between the end portions of the second member and the flanges of the first member at the above-described other of the two parts of the vehicle-body structure can be decreased. Consequently, the proper absorption function of the vehicle collision load with the cooperation of the first and second members can be secured.

According to an embodiment of the present invention, the first and second members are joined to each other such that the pair of flange-ridgeline portions of the first member contacts the both end portions of the second member, respectively, at the above-described one of the two parts of the vehicle-body structure, whereas the inside ends of the both end portions of the second member contact specified positions of the flanges of the first member which are located outside away from the pair of flange-ridgeline portions, respectively, such that a gap is formed between the pair of flange-ridgeline portions of the first member and the second member at the above-described other of the two parts of the vehicle-body structure.

That is, by constituting that a pair of flange-ridgeline portions of the first member contacts the both end portions of the second member, respectively, at the above-described one of the two parts of the vehicle-body structure, the distance between the pair of flange-ridgeline portions of the first member is set be substantially equal to the length of the second member from the inside end of one of the both end portions to the inside end of the other of the both end portions. Meanwhile, by constituting that the inside ends of the both end portions of the second member contact specified positions of the flanges of the first member which are located outside away from the pair of flange-ridgeline portions, respectively, such that the gap is formed between the pair of flange-ridgeline portions of the first member and the second member at the above-described other of the two parts of the vehicle-body structure, the length of the second member from the inside end of one of the both end portions to the inside end of the other of the both end portions is set to be longer than the distance between the pair of flange-ridgeline portions of the first member. Thereby, it can be prevented that the second member is pressed inwardly, in the vehicle width direction, by the flange-ridgeline portions of the first member quickly in an initial stage of deformation of the vehicle-body structure. Accordingly, the shearing load acting on the joint portion between the end portions of the second member and the flanges of the first member can be decreased properly.

According to another embodiment of the present invention, the second member includes beads which are concaved toward an opposite side to the first member at specific positions thereof which face to the pair of flange-ridgeline portions of the first member. Thereby, a large area can be secured at a plane portion of the second member except for the beads. Accordingly, an appropriate load resistance of the second member against a pull load which is generated when the first member is deformed can be secured by the above-described plane portion of the second member, and the shearing load can be decreased by extension of the beads.

According to another embodiment of the present invention, the first member has a rigidity which is higher than that of the second member. Thereby, the above-described decrease effect of the shearing load can be obtained effectively.

According to another embodiment of the present invention, the vehicle-body structure is a center pillar of the vehicle, the longitudinal direction of the vehicle-body structure corresponds to a vertical direction of the vehicle, the first member is a reinforcement of the center pillar, and the second member is an inner panel of the center pillar which is arranged on an inward side, in a vehicle width direction, of the first member. Thereby, since the center pillar of the vehicle which tends to receive the collision load in the vehicle side collision has the above-described structure according to the present invention, passengers can be securely protected from the collision load in the vehicle side collision.

According to another embodiment of the present invention, the above-described one of the two parts of the vehicle-body structure is an upper portion of the center pillar, and the above-described other of the two parts of the vehicle-body structure is a lower portion of the center pillar. Thereby, the appropriate load resistance of the upper portion of the center pillar against the side-collision load can be secured, and the appropriate promotion of deformation of the lower part of the center pillar and the decrease of shearing load can be achieved.

According to another embodiment of the present invention, the first member further comprises a pair of vertical-wall portions which extends continuously from the pair of flanges via the pair of flange-ridgeline portions, at least one of the vertical-wall portions of the first member includes a slant portion which has a specified slant angle such that the vertical-wall portion stands up gradually from the flange portion, and the first member is configured such that the specified angle of the slant portion of the first member at the lower portion of the center pillar is gentler than that of the first member at the upper portion of the center pillar. Thereby, when a force acing inwardly, in the vehicle width direction, is applied to the lower part of the center pillar in the vehicle side collision, the above-described vertical-wall portion is easily deformed so as to fall down, so that crushing of the lower part of the center pillar can be promoted. Meanwhile, the upper part of the center pillar including the upper portion and middle portion of the reinforcement has the vertical-wall portion which is not so gentle, compared with the lower part of the center pillar. Thus, the appropriate load resistance of the upper part of the center pillar against the load acting in the vehicle width direction can be secured properly. Consequently, when the side-collision load acts on the center pillar inwardly, the lower portion of the center pillar including the lower part is deformed greatly first, so that an impact energy of the vehicle side collision can be absorbed by this deformed portion. Meanwhile, the upper portion and the middle portion of the center pillar which includes the upper part having the relatively-high load resistance can be effectively restrained from being deformed. Thus, a situation where the center pillar bends greatly at its middle portion and thereby comes into the inside of the vehicle compartment is prevented, so that any improper interference of the bending center pillar with passengers can be avoided effectively.

According to another embodiment of the present invention, the vertical-wall portion of the first member comprises a base portion which extends substantially in the vehicle width direction and a corner portion which is formed between the base portion and the slant portion. Since the vertical-wall portion of the lower portion of the center pillar bends easily at this corner portion where the stress concentrates in the vehicle side collision and falls down toward the inside of the vehicle (toward the pillar-inner-panel side), the deformation of the lower portion of the center pillar including the above-described lower part can be promoted effectively. Accordingly, the bending of the middle portion of the center pillar is prevented, and thereby the passenger's protection can be achieved securely.

According to another embodiment of the present invention, a hinge attachment portion of a rear door is provided at the upper portion of the center pillar. Thereby, since the rear door is supported at the upper portion of the center pillar having the high load resistance via the door hinge, the support rigidity of the rear door can be increased effectively.

According to another embodiment of the present invention, a hinge attachment portion of a rear door is provided at the center pillar, and a bending promotion portion to cause bending of the center pillar when the center pillar receives a load of vehicle side collision is formed at a specified position of the reinforcement which is located above the hinge attachment portion. Thereby, since the center pillar tends to bend at the bending promotion portion in accordance with the collision load inputted from a lower door hinge, bending of the middle portion of the center pillar can be more securely prevented. Consequently, any improper interference of the bending center pillar with passengers can be avoided more effectively.

According to another embodiment of the present invention, the first member is a press member which is formed through a thermal pressing. Thereby, the center pillar can be reinforced without increasing its weight, so that the middle portion of the center pillar can be more securely prevented from bending in the vehicle side collision.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a preferred embodiment of the present invention and its modifications will be described referring to the accompanying drawings.

FIGS. 1 and 2show a vehicle side portion according to an embodiment of the present invention. An ingress and egress opening1is formed at a side face portion of a vehicle shown in the figures, which is closable with a side door3(FIG. 1). In the figures, an arrow F shows a vehicle forward direction, an arrow R shows a vehicle rearward direction, an arrow IN shows a vehicle inward direction, and an arrow OUT shows a vehicle outward direction.

A four-door sedan type of automotive vehicle is shown inFIGS. 1 and 2, and two ingress and egress openings1are formed at two positions in front and back of a center pillar5which will be described below. A couple of side doors3closes and opens these openings1. Herein, an illustration of a front side door is omitted inFIG. 1, and the side door3illustrated shown here is a rear side door for a rear opening1.

At the side portion of the vehicle are provided a roof side rail7and a side sill9which extend in the vehicle longitudinal direction, which form an upper side and a lower side of the above-described ingress and egress opening1. Respective central portions of the roof side rail7and the side sill9are connected with a center pillar5which extends in a vehicle vertical direction. Herein, a member shown by a two-dotted broken line, which is denoted by reference numeral45inFIG. 2, is an impact bar as a reinforcing member which is provided inside the side door3.

FIGS. 3,4and5are sectional views of the above-described center pillar5, roof side rail7, and side sill9. The center pillar5comprises, as shown inFIG. 3, a pillar outer panel11, a pillar inner panel12which is arranged on an inward side, in a vehicle width direction, of the pillar outer panel11, and a pillar reinforcement13which is arranged between the panels11,12. Likewise, the roof side rail7comprises, as shown inFIG. 4, an outer panel15, an inner panel16, and a reinforcement17. The side sill9comprises, as shown inFIG. 5, an outer panel19, an inner panel20, and a reinforcement21.

Herein, the pillar reinforcement13of the center pillar5is made of a thicker or stronger plate member so that it has a rigidity which is higher than that of the pillar inner panel12.

FIG. 6is a view corresponding toFIG. 2and showing a state in which the above-described pillar outer panel11of the center pillar5, outer panel15of the roof side rail7, and outer panel19of the side sill9are removed. Accordingly, inFIG. 6the respective pillar reinforcements13,17,21of the center pillar5, roof side rail7, and side sill9are illustrated so as to be exposed to the outside, which is different fromFIG. 2.

In the present embodiment, the center pillar5comprises an upper part5aand a lower part5b, as described later, which are separated by shapes of the pillar inner panel12and the pillar reinforcement13. As illustrated inFIG. 6, while the pillar reinforcement13of the center pillar5is comprised of an integral press member which is formed through pressing, it is separated into an upper portion23which constitutes the upper part5aand a lower portion24which constitutes the lower part5bby differences in a shape of their cross section. Reference character P in the figure denotes a border line to separate the upper portion23and the lower portion24, and this border line P is positioned below a middle portion of the pillar reinforcement13in the vehicle vertical direction. That is, the pillar reinforcement13includes integrally the upper portion23above the border line P and the lower portion24below the border line P.

FIG. 7is a perspective view of the pillar reinforcement13which is partially cut away.FIG. 8is a side view of the pillar inner panel, when viewed from the inward side in the vehicle width direction.FIGS. 9 and 10are respective sectional views of the upper portions23,51and the lower portions24,52of the pillar inner panel12and the pillar reinforcement13, taken along lines Y1-Y1and Y2-Y2ofFIG. 6, respectively. As shown inFIGS. 7 and 9, the upper portion23comprises a side-wall portion25which extends along the side face of the vehicle body, a pair of vertical-wall portion26which extends inwardly, in the vehicle width direction, from both end portions of the side-wall portion25, and a pair of flanges27which extends longitudinally from tip portions of the vertical-wall portions26and are joined to the pillar inner panel12of the center pillar5. The pair of vertical-wall portions26extends inwardly, in the vehicle width direction, having an inclination angle θ1(seeFIG. 9), which is about the right angle 90°, relative to the side-wall portion25. The vertical-wall portions26, side-wall portion25and flanges27form a U-shaped cross section of the pillar reinforcement13.

At the upper portion23of the pillar reinforcement13are provided flange-ridgeline portions28of the flanges27which are formed by the vertical-wall portions26and inside end portions of the flanges27.

Further, at the upper portion23, as shown inFIG. 9, is formed an open portion23abetween the pair of flange-ridgeline portions28.

Meanwhile, as shown inFIGS. 7 and 10, the lower portion24of the pillar reinforcement13has a wider shape than the above-described upper portion23. Specifically, the lower portion24comprises a side-wall portion29which extends along the side face of the vehicle body, a pair of vertical-wall portion30which extends inwardly in the vehicle width direction with a slant from both end portions of the side-wall portion29, and a pair of flanges31which extends longitudinally from tip portions of the vertical-wall portions30and are joined to the pillar inner panel12of the center pillar5. Further, at the lower portion24, as shown inFIGS. 6,7and10, is formed a relatively wide opening (through hole)39at the side-wall portion29.

At the lower portion24of the pillar reinforcement13are provided flange-ridgeline portions32at inside end portions of the flanges31which are formed by the vertical-wall portions30and the flanges31.

Further, at the lower portion24, as shown inFIG. 10, is formed an open portion24awhich opens inwardly, in the vehicle width direction, between the pair of flanges31,31.

The pair of vertical-wall portions30of the lower portion24slants so as to enlarge their distance gradually (i.e., each of the portions30extends obliquely outside), and their inclination angle θ2(seeFIG. 10) is set to be greater than that of the vertical-wall portions26of the upper portion23(FIG. 9). That is, the vertical-wall portions26of the upper portion23slants with the angle θ1which is a very small angle relative to the vehicle width direction, whereas the vertical-wall portions30of the lower portion24slants with the angle θ2which is greater (i.e., gentler) than the angle θ1relative to the vehicle width direction.

More specifically, each of the vertical-wall portions30of the lower portion24comprises, as shown inFIG. 10, a base portion30awhich extends inwardly from the end portion of the side-wall portion29and a slant portion30bwhich extends obliquely. A corner portion C is formed between the base portion30aand the slant portion30b.

Herein, the thickness of the lower portion24including the vertical-wall portion30is set to be smaller than that of the upper portion23.

As shown inFIGS. 1 and 2, a pair of door hinges41,42to support the rear side door3is attached to the center pillar5. InFIGS. 6 and 7, specified portions of the pillar reinforcement13to which the door hinges41,42are attached are denoted by reference numerals35,36. As apparent from these figures, the hinge attachment portions35,36are provided at the upper portion23of the pillar reinforcement13, and such hinge attachment portions are not provided at the lower portion24.

The hinge attachment portion36(hereinafter, referred to as “lower hinge attachment portion36”), to which the lower door hinge42is attached, is arranged near a lower end portion of the upper portion23, that is, at a position which is located slightly above the border line P between the upper portion23and the lower portion24. Meanwhile, the hinge attachment portion35(hereinafter, referred to as “upper hinge attachment portion35”), to which the upper door hinge41is attached, is arranged near a middle portion of the upper portion23, that is, at a position which is located above the lower hinge attachment portion36by a specified distance.

As illustrated inFIG. 8, while the pillar inner panel12of the center pillar5is comprised of an integral press member which is formed through pressing, it is separated into an upper portion51which constitutes the upper part5aand a lower portion52which constitutes the lower part5bby differences in a shape of their cross section, like the pillar reinforcement13. Reference character Q in the figure denotes a border line which is positioned at a location of the pillar inner panel12which corresponds to the border line P separating the upper portion23and the lower portion24, of the pillar reinforcement13, that is, at a location below the middle portion of the pillar inner panel12.

That is, the pillar inner panel12includes integrally the upper portion51above the border line Q and the lower portion52below the border line Q.

The upper portion51of the pillar inner panel12is formed in a substantially flat shape, and both end portions53,53of the pillar inner panel12are joined to the flanges27of the upper portion23of the pillar reinforcement13(seeFIG. 9). In the figure, reference character53idenotes an inside end of the end portion53of the pillar inner panel12.

The upper portion51at the upper part5aof the center pillar5is formed in the flat shape as described, so that the length L1of a portion51aof the pillar inner panel12which covers the opening portion23abetween the flange-ridgeline portions28,28, that is, the length L1of the pillar inner panel12from the inside end53iof one of the end portions53to the inside end53iof the other of the end portions53is substantially equal to the distance L2between the flange-ridgeline portions28,28as shown inFIG. 9.

Further, at the upper portion5a, the upper portion23of the pillar reinforcement13is joined to the upper portion51of the pillar inner panel12such that the flange-ridgeline portions28contact the pillar inner panel12. Herein, a situation meant by a term of “contact” includes not only a state of direct contacting of the flange-ridgeline portions28and the pillar inner panel12at a normal condition, but another state in which the flange-ridgeline portions28come to contact the pillar inner panel12directly through deformation of these28,12in an initial stage of the vehicle side collision.

Meanwhile, the both end portions53,53of the lower portion52of the pillar inner panel12are joined to the flanges31,31(seeFIG. 10) of the lower portion24of the pillar reinforcement13. Thus, the lower portion52of the pillar inner panel12covers the opening portion24aof the lower portion24of the pillar reinforcement13from the inward side in the vehicle width direction.

Further, two beads54,54which are concaved outwardly, in the vehicle width direction, are formed at the lower portion52of the pillar inner panel12. The beads54extend in the vehicle vertical at the lower portion52, and as shown inFIG. 10, they are formed at specific positions of the lower portion52which face to the pair of flange-ridgeline portions32of the pillar reinforcement13.

The bead54generates a gap G which is formed between the flange-ridgeline portion32of the lower portion24of the pillar reinforcement13and the lower portion52of the pillar inner panel12. That is, the inside ends53iof the both end portions53of the lower portion52of the pillar inner panel12contact specified positions of the flanges31of the lower portion24of the pillar reinforcement13are located outside away from the pair of flange-ridgeline portions32, respectively, such that the gap G is formed between the flange-ridgeline portions32of the lower portion24of the pillar reinforcement13and the lower portion52of the pillar inner panel12.

Accordingly, the length L3of the portion52a, which covers the opening portion24aof the pillar reinforcement13, of the lower portion52of the pillar inner panel12, that is, the length L3of the lower portion52of the pillar inner panel12from the inside end53iof one of the end portions53to the inside end53iof the other of the end portions53, is longer than the distance L4between the pair of flange-ridgeline portions32of the lower portion24of the pillar reinforcement13, as shown inFIG. 10.

Further, the lower portion52of the pillar inner panel12has an opening (through hole)55which is formed between the two beads54,54as shown inFIGS. 8 and 10. This opening55is positioned at a specified location which substantially corresponds to the opening39of the pillar reinforcement13.

FIG. 11is a sectional view taken along line Y3-Y3ofFIG. 6. In this figure, the respective pillar outer panels11,19of the center pillar5and the side sill9are illustrated by two-dotted broken lines. As shown in this figure, the upper portion23of the pillar reinforcement13is arranged close to the pillar outer panel11in the vehicle width direction at the above-described lower hinge attachment portion36, and these members are overlapped. The above-described lower door hinge42is attached to this overlap portion of the members via bolts, not illustrated. In other words, this lower door hinge42is attached to the lower hinge attachment portion36of the pillar reinforcement13in a state in which the pillar outer panel11is arranged between these members42,36. Herein, the upper door hinge41is also attached to the upper hinge attachment portion35in the same way, which is not illustrated in detail.

Further, as shown inFIGS. 6,7and11, a groove with an arc-shaped cross section34which is concaved inwardly and extends in the vehicle longitudinal direction is formed at a specified position of the upper portion23which is located near a lower end of the upper portion23and slightly above an upper end portion of the above-described lower hinge attachment portion36. This concaved groove34, which corresponds to a bending promotion portion of the present invention, causes the bending deformation of the center pillar5in the vehicle side collision.

FIG. 12is a perspective view showing around a joint portion between the center pillar5and the side sill9. Herein, likeFIG. 6, this figure illustrates this joint portion in a state where the respective outer panels11,19of the center pillar5and the side sill9are removed, and large part of the lower portion24of the pillar reinforcement13is cut away.

As shown inFIGS. 11 and 12, a concaved portion37which is concaved downwardly from an upper face of the above-described reinforcement21is formed at a joint portion of the reinforcement21to the center pillar5. This concaved portion37is, as shown inFIG. 12, formed over a range of the longitudinal length of the center pillar5, and the vertical length H (seeFIG. 11) of the reinforcement21at this range of the concaved portion37is shorter than the other portion without the concaved portion37(i.e., portions located in front and back of the center pillar5) by a concave amount ΔH.

At this concaved portion37is formed a plurality of openings38(three openings in the present embodiment illustrated) so as to be located longitudinally. Specifically, each opening38is of a rectangular shape and arranged such that its four sides match the vehicle longitudinal direction and the vehicle lateral (width) direction, respectively.

Thus, the concaved portion37is formed at the upper face of the reinforcement21of the side sill9at the joint portion between the center pillar5and the side sill9, and further the openings38are formed at the concaved portion37. These concaved portion37and openings38promote deformation of the side sill9in the vehicle side collision, and constitutes a deformation promotion portion, which will be described specifically.

The center pillar5of the present embodiment comprises the pillar reinforcement13which includes the upper portion23and the lower portion24which are integrally provided above and below the border line P, and these portions23,24comprises the side-wall portions25,29which extend along the vehicle side face and the pairs of vertical-wall portions26,30which extend inwardly, respectively. The pair of vertical-wall portions30of the lower portion24of the reinforcement13slants such that the distance therebetween increase gradually inwardly. Thus, the slant angle of the of vertical-wall portions30of the lower portion24of the reinforcement13is gentler than that of the vertical-wall portions26of the upper portion23of the reinforcement13. Accordingly, the center pillar5can be restrained from coming into the inside of the vehicle compartment with a simple structure.

That is, since the pair of vertical-wall portions30of the lower portion24of the reinforcement13slants such that the distance therebetween increase gradually inwardly according to the present embodiment, when the vehicle side collision occurs and thereby the collision force acts on the lower portion24inwardly, the vertical-wall portions30are deformed easily so as to fall down (toward the pillar inner panel12), so that crushing of the lower portion24is promoted. Meanwhile, since the vertical-wall portions26of the upper portion23including the upper portion and the middle portion of the pillar reinforcement13do not slant so much as the vertical-wall portions30of the lower portion24of the reinforcement13, the load resistance of the upper portion23of the reinforcement18against the collision load can be properly secured. Thus, when the side-collision load acting inwardly is inputted to the center pillar5, the lower portion of the center pillar5including the lower portion24is deformed greatly, so that the impact energy of the vehicle collision can be absorbed at this portion. Meanwhile, the deformation at the upper portion and the middle portion of the center pillar5including the upper portion23having the relatively high load resistance can be effectively restrained. The center pillar5is deformed in this deformation mode, so that it can be avoided that the center pillar5bends at the middle portion, in the vehicle vertical direction, and thereby comes into the inside of the vehicle compartment. Thereby, any improper interference of the center pillar5with passengers can be prevented effectively.

This will be described specifically referring toFIG. 13. In this figure, the center pillar5in its normal state is shown by a solid line, and the one in its bending state when receiving the side-collision load is shown by a one-dotted broken line. Herein, a broken line imaginarily shows a state of the center pillar5before its bending (a deformation mode except for a bending mode). When the side-collision load is inputted to the center pillar5as shown inFIG. 13, the center pillar5is deformed inwardly, in the vehicle width direction, in accordance with the side-collision load. Herein, in case the lower portion24of the pillar reinforcement13is configured so as to be crushed easily as described above, the modulus of section of the lower portion of the center pillar5becomes smaller quickly by this crush, and thereby the bending deformation is promoted. Consequently, the center pillar5bends greatly at its lower portion and moves inwardly. Meanwhile, since the upper portion23of the pillar reinforcement13having the high load resistance is provided at the upper portion and the middle portion of the center pillar5, the amount of deformation of the upper portion and the middle portion of the center pillar5is relatively small. InFIG. 12, the reason why the upper portion and the middle portion of the center pillar5have little bending, but only the lower portion of the center pillar5bends mainly is this.

Meanwhile, in case the center pillar5bends at the middle portion as shown inFIG. 14, for example, this middle portion greatly comes into the inside of the vehicle compartment, so that there is a concern that the center pillar5would come to interfere with passengers. According to the present embodiment, however, the lower portion24of the pillar reinforcement13has the easily-crushable shape (structure) and thereby this lower portion24is greatly deformed in the vehicle side collision, so that the bending of the middle portion of the center pillar5can be prevented. Thereby, since the maximum inward-deformation amount D (FIG. 13) of the center pillar5is restrained so as to be smaller than the maximum inward-deformation amount D′ (FIG. 14) in case the center pillar5bends at the middle portion, the amount of the center pillar5coming into the inside of the vehicle compartment can be effectively decreased, so that the safety of the passengers can be properly secured.

Moreover, according to the above-described structure, the bending of the middle portion of the center pillar5can be restrained by the very simple means of changing the sectional shape of the pillar reinforcement13(i.e., the upper portion23has the different sectional shape from the lower portion24). Thereby, the center pillar5can be restrained from coming into the inside of the vehicle compartment more simply and effectively in the vehicle side collision.

Hereinafter, the move of the lower part5bof the center pillar5when the center pillar bends will be described referring toFIG. 15.FIG. 15Ais a sectional view of the lower part of the center pillar which explains an initial stage of the bending of the center pillar, andFIG. 15Bis a sectional view of the lower part of the center pillar which explains a late stage of bending of the center pillar. As shown inFIG. 13, in case the center pillar5bends when receiving the side-collision load, at the lower part5bwhere the deformation is promoted, the side-wall portion29of the lower portion24of the pillar reinforcement13starts crushing longitudinally along with a side-wall portion of the pillar outer panel11in the initial stage, as shown inFIG. 15A.

Thereby, at the lower portion24, the flange-ridgeline portions32are deformed and thereby approaches the pillar inner panel12, and also the tips of the flanges31,31, which are joined to the pillar outer panel11and the pillar inner panel12, are pulled outwardly, that is, in a direction of peeling the flanges31,31off the both end portions53,53of the lower portion52of the pillar inner panel12.

Herein, the both end portions53,53are pulled longitudinally by the above-described pull load of the flanges31at the lower portion52of the pillar inner panel12, and the beads54,54are extended longitudinally by the above-described pull load as shown inFIG. 15A.

Then, as the deformation of the lower part5aof the center pillar5progresses, in a middle stage of the vehicle side collision, the flange-ridgeline portions32come into inside spaces of the concaved beads54(that is, the flange-ridgeline portions32come into the gaps G formed between the flange-ridgeline portions32and the pillar inner panel12). Further, in the late stage, the flange-ridgeline portions32come to contact the extended beads as shown inFIG. 15B. After this contact of these portions32,54, the beads54are further extended in accordance with the deformation of the flange-ridgeline portions32, and finally the flange-ridgeline portions32and the beads54are deformed to curve together so as to overlap with each other, keeping a joint state between the flanges31and the both end portions53.

According to the present embodiment, since the length L3of the covering portion52aof the lower portion52, that is, the length L3(seeFIG. 10) of the lower portion52from the inside end53iof one of the end portions53to the inside end53iof the other of the end portions53, is longer than the distance L4(seeFIG. 10) between the pair of flange-ridgeline portions32,32, the covering portion52aof the lower portion52of the pillar inner panel12can be deformed properly in accordance with the deformation of the flange flange-ridgeline portions32. Thereby, the shearing load acting on the joint portion between the both end portions53of the lower portion52of the pillar inner panel12and the flanges31of the lower portion24of the pillar reinforcement13can be decreased, so that detachment of these portions53,31can be prevented.

Accordingly, by configuring that at one of the two parts of the center pillar5(the upper part5a), the length L1of the covering portion51a(that is, the length L1from the inside end53iof one of the both end portions53to the other inside end53iof the other of the both end portions53) (seeFIG. 9) is substantially equal to the distance L2between the pair of flange-ridgeline portions28,28(seeFIG. 9), whereas, at the other part of the center pillar5(the lower part5b), the length L3of the covering portion52aof the pillar inner panel12(that is, the length L3from the inside end53iof one of the both end portions53to the other inside end53iof the other of the both end portions53) (seeFIG. 10) is longer than the distance L4between the pair of flange-ridgeline portions32,32of the pillar reinforcement13(seeFIG. 10), the decreasing of the shearing load can be achieved properly, securing the appropriate load resistance of the upper part5aagainst the side-collision load and promoting the deformation of the lower part5b.

Further, since the beads54are formed so as to generate the gap G between the flange-ridgeline portions32and the pillar inner panel12to secure the above-described length L3of the lower portion52of the pillar inner panel12, it can be prevented that the pillar inner panel12is pressed inwardly quickly by the flange-ridgeline portions32at the initial stage of the deformation of the center pillar5. Thus, the above-described shearing load acting on the joint portion between the both end portions53of the pillar inner panel12and the flanges31of the pillar reinforcement13can be further decreased.

Particularly, since the beads54are formed only at the specific positions which face to the flange-ridgeline portions32, a large area can be secured at a plane (straight) portion of the covering portion52aof the pillar inner panel12except for the beads54. Accordingly, the appropriate load resistance against the above-described pull load in the deformation of the pillar reinforcement13can be secured by the above-described plane portion, and the shearing load can be decreased by the extension of the beads54.

The present inventors found through their researches that the above-described shearing load becomes greater in case the rigidity of the pillar reinforcement13is set to be greater than that of the pillar inner panel12. Therefore, the effect of the decrease of the shearing load by setting the length L3of the covering portion52awhich covers the opening portion24abetween the pair of flange-ridgeline portions32,32becomes more outstanding in case the rigidity of the pillar reinforcement13is greater than that of the pillar inner panel12.

Especially, since the above-described decrease structure of the shearing load is applied to the center pillar5which may easily receive the collision load in the vehicle side collision as the present embodiment, any passenger in the vehicle compartment can be protected more securely from the collision load.

Further, according to the present embodiment, as shown inFIG. 10, the vertical-wall portion30of the lower portion24of the pillar reinforcement13comprises the base portion30awhich extends inwardly, in the vehicle width direction, from the side-wall portion29, the slant portion30bwhich extends obliquely, and the corner portion C between these portions30a,30b. Since the vertical-wall portion30of the lower portion24bends easily at this corner portion C where the stress may concentrate in the vehicle side collision and falls down toward the inside of the vehicle (toward the pillar-inner-panel side), the deformation of the lower portion of the center pillar5including the lower portion24can be promoted effectively. Accordingly, the bending of the middle portion of the center pillar5is prevented, and thereby the passenger's protection can be achieved securely.

Moreover, since the relatively large opening39(seeFIGS. 6 and 7) is formed at the lower portion24of the pillar reinforcement13in the present embodiment, the load resistance of the lower portion24can be lower than that of the upper portion23, so that deformation of the lower portion of the center pillar5in the vehicle side collision can be promoted more effectively.

According to the present embodiment, as shown inFIGS. 2,6,7and others, the hinge attachment portions35,36of the door hinges41,42for the rear side door3are provided at the upper portion23of the pillar reinforcement13. Thereby, since the rear door is supported at the upper portion23having the high load resistance via the door hinges41,42, the support rigidity of the rear side door3can be increased effectively.

More specifically, according to the present embodiment, the lower hinge attachment portion36of the lower door hinge42for the rear side door3is provided near the lower end of the upper portion23, and the concaved groove34as the bending promotion portion to cause bending of the center pillar5in the vehicle side collision is formed at the specified position which is located above the lower hinge attachment portion36. Thereby, since the center pillar5tends to bend at the position of the concaved groove23a(a portion A inFIG. 13) in accordance with the collision load inputted from the lower door hinge, bending of the middle portion of the center pillar5can be more securely prevented. Consequently, any improper interference of the bending center pillar with passengers can be avoided more effectively.

That is, the load applied to the rear side door3in the vehicle side collision is transmitted via the impact bar45as the reinforcing member (FIG. 2) mainly, and then inputted to the center pillar5via the pair of door hinges41,42. Herein, in case the lower door hinge42is attached near the lower end of the upper portion23and the concaved groove34is provided above its attachment portion (lower hinge attachment portion36) as described above, when the side-collision load is inputted from the lower door hinge42, the pillar reinforcement13bends at the weak concaved groove34. Thereby, it can be effectively prevented that the center pillar5bends at the middle portion, in the vehicle vertical direction, so that it interferes with passengers.

As shown inFIGS. 11 and 12, the concaved portion37as the deformation promotion portion which promotes the deformation of the side sill9when the center pillar5receives the vehicle side collision is formed at the upper face of the reinforcement21of the side sill9which corresponds to the joint portion to the center pillar5. Thereby, the vertical width of the reinforcement21becomes smaller by the one of the concaved portion37, so that the rigidity of the joint portion of the side sill9to the center pillar5becomes lower than that of the other portion. Also, the bending deformation of the reinforcement21caused by the border portion (corner portion) between the upper face of the reinforcement21and the concaved portion37is promoted. Accordingly, it can be effectively prevented that the deformation of the lower portion of the center pillar5is hindered by the side sill9in the vehicle side collision, so that a desired deformation mode (FIG. 13) may not be obtained.

That is, it is necessary for the lower portion (portion corresponding to the lower portion24of the pillar reinforcement13) of the center pillar5to be deformed greatly and bend in order that the center pillar5can be deformed in the deformation mode shown by the one-dotted broken line inFIG. 13. Therefore, it is also necessary that the side sill9is relatively greatly deformed accordingly. In this case, however, if the rigidity of the side sill9is too high, the deformation may be restrained too much, so that there is a concern that the deformation of the center pillar5in the above-described mode would be deteriorated by the side sill9. According to the present embodiment, however, since the concaved portion37is formed at the joint portion of the side sill9to the center pillar5, the deformation of the side sill9can be promoted in the vehicle side collision by an existence of the concaved portion37, so that the deformation in the desired mode shown by the one-dotted broken line inFIG. 13can be securely provided.

Moreover, since the openings38are formed at the specified portion of the upper face of the reinforcement21of the side sill9where the concaved portion37are positioned in the present embodiment, the rigidity of this portion of the side sill9can be lower than that of the other portion of the side sill9. Thereby, the improper situation where the side sill9hinders the deformation of the center pillar5so that the desired deformation mode may not be obtained can be prevented effectively.

Particularly, according to the present embodiment, since the opening38is of the rectangular shape and arranged such that its four sides match the vehicle longitudinal direction and the vehicle width direction, respectively, the desired deformations of the side sill9both in the vehicle longitudinal direction and the vehicle width direction can be promoted by the opening38. Thus, the above-described deformation of the center pillar5in the desired mode can be more securely achieved.

Herein, while the material of the pillar reinforcement13has not been described in particular, it may be preferable that it be made of a press member which is formed through a thermal pressing (hot stamping), for example. The thermal pressing means a process in which a steel plate in its heated state is pressed by using a die. In this process, the rigidity of the steel plate can be increased considerably through its hardening which is caused by a quick cooling with the die. In case the pillar reinforcement13is made of the press member formed through the thermal pressing, the center pillar5can be reinforced without increasing its weight, and bending of its middle portion in the vehicle side collision can be prevented securely.

While using the press member formed through the thermal pressing for the pillar reinforcement13may cause reinforcing the lower part of the center pillar5which is required to be deformed relatively greatly, the load resistance of this lower part of the center pillar5against the side-collision load can be properly decreased relatively by configuring the shape of the lower portion24of the pillar reinforcement13as described above (i.e., the vertical-wall portions30of the lower portion24slant greatly and the like). Consequently, even if the pillar reinforcement13is made of the press member formed through the thermal pressing, the desired deformation mode shown inFIG. 13can be obtained properly.

Further, in case the vertical-wall portion30of the lower portion24is formed in the bend shape in which the corner portion C is formed between the base portion30aand the slant portion30b(seeFIG. 10) like the present embodiment, there occurs a difference in the cooling speed during the thermal pressing between the base portion30aand the slant portion30b, so that there exists a specified difference in the rigidity between them as well. This rigidity difference can secure the situation where the corner portion C causes the deformation in the vehicle side collision, and thereby the lower portion24can be crushed more easily. Thus, the lower part of the center pillar5including the lower portion24is greatly deformed relatively in the vehicle side collision, so that the bending of the middle portion of the center pillar5can be prevented more securely.

While both the concaved portion37and the openings38are formed at the joint portion of the side sill9to the center pillar5as the formation promotion portion to promote the side sill9in the side collision in the present embodiment, only any one of the concaved portion37and the openings38may be provided because it is fine that the deformation of the side sill9is promoted to a degree in that the deformation of the center pillar5in the desired deformation mode may not be hindered.

While the two beads54are formed to secure the length L3of the covering portion52aof the lower portion52of the pillar inner panel12in the present embodiment, the present invention should not be limited to this. For example, as shown inFIGS. 16A and 16B, a pillar inner panel112(a lower portion152) and a pillar inner panel212(a lower portion252) may be formed to have a U-shaped cross section, respectively, so that the above-described length of a covering portion152aand a covering portion252acan be secured. Herein, the same components as those of the above-described embodiment are denoted by the same reference characters, descriptions of which are omitted here.

In an example shown inFIG. 16A, a side-face portion154which is formed between both end portions153,153of the pillar inner panel112is formed to project inwardly in the vehicle width direction. In another example shown inFIG. 16B, meanwhile, a side-face portion254which is formed between the both end portions253,253of the pillar inner panel212is formed to project outwardly, i.e., toward the pillar reinforcement13.

Further, in the examples shown inFIGS. 16A and 16B, respective inside ends153i,253iof the both end portions153,253of the pillar inner panels112,212(lower portions152,252) are located outside away from the flange-ridgeline portion32of the pillar reinforcement13as well as the above-described embodiment. Thereby, as described in the above-described embodiment, some gap G is formed between the flange-ridgeline portion32of the pillar reinforcement13and the pillar inner panels112,212.

However, the present invention should not be limited to the above-described structure in which the inside ends of the end portions of the pillar inner panel are located outside away from the flange-ridgeline portions of the pillar reinforcement such that the gap are formed between the flange-ridgeline portions of the pillar reinforcement and the pillar inner panel as long as the length L3of the covering portion is longer than the distance between the pair of flange-ridgeline portions. For example, as shown inFIG. 16C, the flange-ridgeline portions32,32of the pillar reinforcement13may contact a pillar inner panel312as long as the above-described necessary length of a covering portion352aof the pillar inner panel312(lower portion352), that is, the length from an inside end353iof its end portion353to another inside end353iof the end portion353, is secured by forming beads354,354. Herein, inFIGS. 16A-16C, reference numerals155,255,355denote openings which correspond to the opening55formed at the pillar inner panel12(lower portion52), respectively.