Vehicle-body structure of vehicle

A side door comprises a door panel portion and a reinforcement portion (a lower-side reinforcement portion and others). The door panel portion is provided to cover an opening portion for entrance and configured such that its peripheral part overlaps with an opening-portion-forming vehicle-body frame member (a side sill and others) in a vehicle side view. The reinforcement portion is provided at the peripheral part of the door panel portion such that it overlaps with the opening-portion-forming vehicle-body frame member in the vehicle side view, thereby reinforcing the peripheral part of the door panel portion against a collision load applied to the side door from a vehicle side. The reinforcement portion is provided at a portion of the peripheral part of the door panel portion which includes a part corresponding to the vehicle-width-direction-extending vehicle-body frame member (a first floor cross member and others).

BACKGROUND OF THE INVENTION

The present invention relates to a vehicle-body structure of a vehicle.

Conventionally, in a vehicle which comprises a vehicle-body frame member (a center pillar, a side sill, and others) which forms an opening portion for entrance at a vehicle side part and a side door provided so as to open and close the opening portion, a structure of the side door to cope with a vehicle side collision has been developed (see Japanese Patent Laid-Open Publication No. 2018-52138, for example).

The above-described patent document discloses a door (side door) for a vehicle which is provided with panel portions which are arranged on a cabin inward side and on a cabin outward side, a frame portion which is arranged between the panel portions and configured to have a closed-cross section, and a reinforcement portion which is connected to the frame portion. The frame portion of the door for the vehicle comprises front and rear parts which respectively extend in a vertical direction at vehicle front-side and rear-side portions of the panel portions and a lower part which interconnects respective lower portions of the front and rear parts. The reinforcement portion comprises a first reinforcement which interconnects the above-described front and rear parts and a second reinforcement which interconnects the first reinforcement and the above-described lower part.

Herein, a vehicle-body structure of the vehicle is required to suppress a center pillar from coming into a cabin as much as possible in the vehicle side collision. Recently, weight reduction of the vehicle (light-weight vehicle) is also required from viewpoints of the fuel economy and the like. Therefore, it is necessary to compatibly attain the further weight reduction of the vehicle and increasing of the amount of absorption of the collision load (the collision-load absorption performance) in the vehicle side collision. In the door disclosed in the above-described patent document, however, since it is necessary to provide both the frame portion and the reinforcement portion, the weight of the door and therefore the weight of the vehicle is so increased that it may be difficult to satisfy the above-described requirements.

SUMMARY OF THE INVENTION

The present invention has been devised in view of the above-described matter, and an object of the present invention is to provide a vehicle-body structure of a vehicle which can compatibly attain the weight reduction of the vehicle and increasing of the amount of absorption of the collision load in the vehicle side collision.

The present invention is a vehicle-body structure of a vehicle, comprising an opening-portion-forming vehicle-body frame member forming an opening portion for entrance at a vehicle side part, a side door provided so as to open and close the opening portion, and a vehicle-width-direction-extending vehicle-body frame member extending in a vehicle width direction from a portion, in a peripheral direction of the opening portion, of the opening-portion-forming vehicle-body frame member, wherein the side door comprises a door panel portion and a reinforcement portion, the door panel portion being provided to cover the opening portion and configured such that a peripheral part thereof overlaps with the opening-portion-forming vehicle-body frame member in a vehicle side view (i.e., when viewed from the vehicle width direction), the reinforcement portion being provided at the peripheral part of the door panel portion such that the reinforcement portion overlaps with the opening-portion-forming vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction), thereby reinforcing the peripheral part of the door panel portion against a collision load applied to the side door from a vehicle side, and the reinforcement portion is provided at a portion of the peripheral part of the door panel portion which includes a part corresponding to the vehicle-width-direction-extending vehicle-body frame member.

According to the present invention, the side door closing the opening portion is moved (pushed) toward the cabin and comes to contact the vehicle-body frame member in the vehicle side collision. At this moment, the door panel portion of the side door receives a reaction load from the vehicle-body frame member in addition to the collision load. Since the reinforcement portion is provided to overlap with the opening-portion-forming vehicle-body frame member in the vehicle side view, the door panel portion has high rigidity against the reaction load from the opening-portion-forming vehicle-body frame member. Accordingly, deformation of the peripheral part of the door panel portion is suppressed by the reinforcement portion. Thereby, even if the door panel portion receives the collision load and the reaction load from the opening-portion-forming vehicle-body frame member, it is suppressed that the peripheral part of the door panel portion comes into the cabin through the opening portion of the opening-portion-forming vehicle-body frame member, so that the above-described peripheral part of the door panel portion remains contacting with the opening-portion-forming vehicle-body frame member (i.e., a connection state of the above-described portions of the peripheral part of the door panel portion and the vehicle-body frame member is maintained). Consequently, the collision load of the vehicle side collision is transmitted from the side door to the vehicle-body frame member, being dispersed to the peripheral part of the door panel portion.

Further, since the reinforcement portion is provided at the portion of the peripheral part of the door panel portion which corresponds to the vehicle-width-direction-extending vehicle-body frame member, the collision load of the vehicle side collision is properly transmitted to the vehicle-width-direction-extending vehicle-body frame member. Consequently, the above-described dispersion and transmission of the collision load of the vehicle side collision is effectively attained.

Meanwhile, the above-described reinforcement portion can be made of a plate member, for example. Thereby, it is unnecessary that the plate thickness of an impact bar which is conventionally provided is made thick or this impact bar is made of a frame member having a closed-cross section in order to increase the amount of absorption of the collision load in the vehicle side collision. It is also unnecessary that the number of impact bar is increased or a new impact bar is added. Consequently, any weight increase of the door panel portion, thereby any weight increase of the vehicle can be suppressed.

Accordingly, the weight reduction of the vehicle and increasing of the amount of absorption of the collision load in the vehicle side collision can be compatibly attained.

In an embodiment of the above-described vehicle-body structure of the vehicle according to the present invention, the reinforcement portion provided to overlap with a side sill which constitutes the opening-portion-forming vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction) is provided at the peripheral part of the door panel portion such that the reinforcement portion overlaps with a floor cross member which constitutes the vehicle-width-direction-extending vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction).

According to this embodiment, the peripheral part of the door panel, particularly its lower portion is so reinforced that the collision load of the vehicle side collision can be properly transmitted from this lower portion to the opening-portion-forming vehicle-body frame member (the side sill) and the vehicle-width-direction-extending vehicle-body frame member (the floor cross member).

In another embodiment of the above-described vehicle-body structure of the vehicle according to the present invention, the reinforcement portion provided to overlap with a hinge pillar which constitutes the opening-portion-forming vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction) is provided at the peripheral part of the door panel portion such that the reinforcement portion overlaps with an instrument-panel member which constitutes the vehicle-width-direction-extending vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction).

According to this embodiment, the peripheral part of the door panel, particularly its front-side portion is so reinforced that the collision load of the vehicle side collision can be properly transmitted from this front-side portion to the opening-portion-forming vehicle-body frame member (the hinge pillar) and the vehicle-width-direction-extending vehicle-body frame member (the instrument-panel member).

In further another embodiment of the above-described vehicle-body structure of the vehicle according to the present invention, the reinforcement portion provided to overlap with a roof side rail which constitutes the opening-portion-forming vehicle-body frame member in the vehicle side view (i.e., when viewed from the vehicle width direction) is provided at the peripheral part of the door panel portion such that at least a part of the reinforcement portion is located substantially at the same position, in a vehicle longitudinal direction, as a roof cross member which constitutes the vehicle-width-direction-extending vehicle-body frame member.

According to this embodiment, the peripheral part of the door panel, particularly its upper portion is so reinforced that the collision load of the vehicle side collision can be properly transmitted from this upper portion to the opening-portion-forming vehicle-body frame member (the roof side rail) and the vehicle-width-direction-extending vehicle-body frame member (the roof cross member).

The present invention will become apparent from the following description which refers to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

Hereafter, an embodiment of the present invention will be described referring to the drawings. In the following description, front, rear, left, right, upper and lower which respectively mean directions relative to a vehicle1will be simply referred to as “front,” “rear,” “left,” “right,” “upper,” and “lower.”

FIG. 1shows a left-side side part of the vehicle1to which a vehicle-body structure according to the present embodiment is applied. The vehicle1is a 4-door type of passenger car. In the present embodiment, since the vehicle-body structure of the vehicle1is configured to be laterally symmetrical, the vehicle-body structure of the left-side part of the vehicle1will be described specifically only, and detailed explanation of the one of a right-side part of the vehicle1will be omitted. Further, in the following description, there is a case where an inward side, in a vehicle width direction, of the vehicle1will be simply referred to as “right side” and also an outward side, in the vehicle width direction, of the vehicle1will be simply referred to as “left side.”

The vehicle1comprises, as shown inFIGS. 1 and 2, a vehicle-body frame member2which forms front-side and rear-side opening portions for entrance3,4at its left-side side part, through which a passenger gets on or gets off. A front side door5is arranged at the front-side opening portion3so as to open and close this opening portion3. A rear side door6is arranged at the rear-side opening portion4so as to open and close this opening portion4.

The vehicle-body frame member2comprises, as shown inFIG. 2, a side sill10which is arranged at a lower part of the vehicle1and extends in a longitudinal direction, a hinge pillar20which extends upwardly from a front-side end portion of the side sill10, a front pillar30which extends obliquely rearwardly-and-upwardly from an upper-side end portion of the hinge pillar20, and a roof side rail31which continuously extends rearwardly from a rear-side end portion of the front pillar30. The vehicle-body frame member2further comprises a center pillar40which extends in a vertical direction and interconnects a central part, in the longitudinal direction, of the side sill10and a central part, in the longitudinal direction, of the roof side rail31. The front-side opening portion3is partitioned by the side sill10, the hinge pillar20, the front pillar30, the roof side rail31, and the center pillar40.

Further, the vehicle-body frame member2comprises a wheel arch50which extends upwardly-and-rearwardly in an arch shape from a rear-side end portion of the side sill10and forms a part of a wheel house and a quarter pillar51which extends vertically and interconnects the wheel arch50and the roof side rail31. The rear-side opening portion4is partitioned by the side sill10, the roof side rail31, the center pillar40, the wheel arch50, and the quarter pillar51.

The side sill10comprises, as shown inFIG. 4, a side-sill inner panel11which is positioned on the inward side, in the vehicle width direction, of the vehicle1(on the right side in this figure) and has a hat-shaped cross section and a side-sill outer panel12which is positioned on the outward side, in the vehicle width direction, of the vehicle1(on the left side in this figure) and has a hat-shaped cross section. The cross section of the side-sill inner panel11is opened to the left side, and the cross section of the side-sill outer panel12is opened to the right side. Each of the side-sill inner panel11and the side-sill outer panel12has side-sill flanges13which extend in the vertical direction and in the longitudinal direction at its upper-side end portion and its lower-side end portion. The respective side-sill flanges13overlap with each other in the vehicle width direction and are welded together. Thus, a closed-cross section is formed by the side-sill inner panel11and the side-sill outer panel12.

The side-sill outer panel12comprises, as shown inFIG. 4, a side-sill upper wall portion12awhich extends toward the left side from a lower-side end portion of the upper-side side-sill flange13, a side-sill lower wall portion12bwhich extends, facing the side-sill upper wall portion12ain the vertical direction, and a side-sill side wall portion12cwhich interconnects a left-side end portion of the side-sill upper wall portion12aand a left-side end portion of the side-sill lower wall portion12bin the vertical direction.

A first side-sill reinforcement14and a second side-sill reinforcement15are provided inside the side sill10. The first side-sill reinforcement14is configured to have a hat-shaped cross section which is opened to the right side, and arranged along the side-sill outer panel12. The second side-sill reinforcement15is of a flat plate shape. Respective end portion, in the vertical direction, of the first side-sill reinforcement14overlap with the respective side-sill flanges13in the vehicle width direction and are welded together with the side-sill flanges13.

As shown inFIG. 4, a left-side end portion of a floor panel16which expands in the longitudinal direction and in the vehicle width direction is joined to a lower-side portion of the side-sill inner panel11. Further, a left-side end portion of a first floor cross member17which extends in the vehicle width direction is joined to an upper-side portion of the side-sill inner panel11. A floor side rail18which extends in the longitudinal direction is joined to a lower face of the floor panel16. The first floor cross member17is a vehicle-width-direction-extending vehicle-body frame member which extends in the vehicle width direction.

The hinge pillar20comprises two front-door hinges21to support the front side door5(seeFIG. 2). The two front-door hinges21are provided to be spaced apart from each other in the vertical direction.

The hinge pillar20comprises, as shown inFIG. 5, a hinge-pillar inner panel22which is positioned on the inward side, in the vehicle width direction, of the vehicle1(on the right side in this figure) and has a hat-shaped cross section and a hinge-pillar outer panel23which is positioned on the outward side, in the vehicle width direction, of the vehicle1(on the left side in this figure) and has a hat-shaped cross section. The cross section of the hinge-pillar inner panel22is opened to the left side, and the cross section of the hinge-pillar outer panel23is opened to the right side. Each of the hinge-pillar inner panel22and the hinge-pillar outer panel23has hinge-pillar flanges24which extend in the vertical direction and in the longitudinal direction at its front-side end portion and its rear-side end portion. The respective hinge-pillar flanges24overlap with each other in the vehicle width direction and are welded together. Thus, a closed-cross section is formed by the hinge-pillar inner panel22and the hinge-pillar outer panel23.

The hinge-pillar outer panel23comprises, as shown inFIG. 5, a hinge-pillar front wall portion23awhich extends toward the left side from a rear-side end portion of the upper-side hinge-pillar flange24, a hinge-pillar rear wall portion23bwhich extends, facing the hinge-pillar front wall portion23ain the longitudinal direction, and a hinge-pillar side wall portion23cwhich interconnects a left-side end portion of the hinge-pillar front wall portion23aand a left-side end portion of the hinge-pillar rear wall portion23bin the longitudinal direction.

A hinge-pillar reinforcement25is provided inside the hinge pillar20. The hinge-pillar reinforcement25is configured to have a hat-shaped cross section which is opened to the right side, and arranged along the hinge-pillar outer panel23. Respective end portions, in the longitudinal direction, of the hinge-pillar reinforcement25overlap with the respective hinge-pillar flanges24in the vehicle width direction and are welded together with the hinge-pillar flanges24.

As shown inFIG. 5, a left-side end portion of an instrument-panel member26extending in the vehicle width direction is joined to an upper part of the hinge-pillar inner panel22. The instrument-panel member26is provided with hinges26ato pivotably support a glove box in the vertical direction and others. A dash panel27which partitions a cabin from an engine room is joined to a front-side end portion of the hinge-pillar inner panel22. The instrument-panel member26is another vehicle-width-direction-extending frame member.

As shown inFIG. 2, the center pillar40is provided with two rear-door hinges41to support the openable rear side door6. The two rear-door hinges41are provided to be spaced apart from each other in the vertical direction. The center pillar40is further provided with a striker42at its front-side position which is located slightly below the upper-side rear-door hinge41. The striker42is a member to lock the front side door5in a closed state.

The center pillar40comprises, as shown inFIG. 6, a center-pillar inner panel43which is positioned on the inward side, in the vehicle width direction, of the vehicle1(on the right side in this figure) and has a hat-shaped cross section and a center-pillar outer panel44which is positioned on the outward side, in the vehicle width direction, of the vehicle1(on the left side in this figure) and has a hat-shaped cross section. The cross section of the center-pillar inner panel43is opened to the left side, and the cross section of the center-pillar outer panel44is opened to the right side. Each of the center-pillar inner panel43and the center-pillar outer panel44has center-pillar flanges45which extend in the vertical direction and in the longitudinal direction at its front-side end portion and its rear-side end portion. The respective center-pillar flanges45overlap with each other in the vehicle width direction and are welded together. Thus, a closed-cross section is formed by the center-pillar inner panel43and the center-pillar outer panel44.

The center-pillar outer panel44comprises, as shown inFIG. 6, a center-pillar front wall portion44awhich extends toward the left side from a rear-side end portion of the front-side center-pillar flange45, a center-pillar rear wall portion44bwhich extends, facing the center-pillar front wall portion44ain the longitudinal direction, and a center-pillar side wall portion44cwhich interconnects a left-side end portion of the center-pillar front wall portion44aand a left-side end portion of the center-pillar rear wall portion44bin the longitudinal direction.

A center-pillar reinforcement46is provided inside the center pillar40. The center-pillar reinforcement46is configured to have a hat-shaped cross section which is opened to the right side, and arranged along the center-pillar outer panel44. Respective end portion, in the longitudinal direction, of the center-pillar reinforcement46overlap with the respective center-pillar flanges45in the vehicle width direction and are welded together with the center-pillar flanges45.

As shown inFIG. 2, a lower-side end portion of the center pillar40is located substantially at the same position as a second floor cross member47. The second floor cross member47is another vehicle-width-direction-extending vehicle-body frame member.

The roof side rail31comprises, as shown inFIG. 7, a roof-side inner panel32which is positioned on the inward side, in the vehicle width direction, of the vehicle1(on the right side in this figure) and a roof-side outer panel33which is positioned on the outward side, in the vehicle width direction, of the vehicle1(on the left side in this figure) and has a C-shaped cross section. The cross section of the roof-side outer panel33is opened to the right side. The roof-side outer panel33has a roof-side flange34which extends in the vertical direction and in the longitudinal direction at its lower-side end portion. The roof-side flange34overlaps with a lower-side end portion of the roof-side inner panel32in the vehicle width direction and these are welded together. An upper-side end portion of the roof-side outer panel33overlaps with an upper-side end portion of the roof-side inner panel32in the vehicle width direction and these are welded together. Thus, a closed-cross section is formed by the roof-side inner panel32and the roof-side outer panel33.

A roof-side reinforcement35is provided inside the roof side rail31. The roof-side reinforcement35is configured to have a hat-shaped cross section which is opened to the right side, and arranged along the roof-side outer panel33. A lower-side end portion of the roof-side reinforcement35overlaps with a lower-side end portion of the roof-side inner panel32and the roof-side flange34of the roof-side outer panel33in the vehicle width direction and these are welded together. Meanwhile, an upper-side end portion of the roof-side reinforcement35overlaps with an upper-side end portion of the roof-side inner panel32and an upper-side end portion of the roof-side outer panel33in the vehicle width direction and these are welded together.

As shown inFIG. 7, a roof cross member36which extends in the vehicle width direction is provided on the right side of the roof side rail31. A left-side end portion of the roof cross member36is joined to the roof side rail31. The roof cross member36is another vehicle-width-direction-extending vehicle-body frame member.

Herein, a structure of a cross section of the front pillar30is similar to that of a cross section of the roof side rail31which is continuous to the front pillar30.

Next, the front side door5will be described as an example of a side-door structure. In the following description, a state where the front side door5closes the front-side opening portion3is a premise. Herein, while detailed description of the rear side door6is omitted, the rear side door6has substantially the same structure as the front side door5except a shape of its door panel portion60and arrangement and a shape of its reinforcement portions, which will be described later.

The front side door5comprises, as shown inFIGS. 4-8, the door panel portion60which has a door inner panel61which is positioned on the inward side, in the vehicle width direction, of the vehicle (on the right side in this figure) and a door outer panel62which is positioned on the outward side, in the vehicle width direction, of the vehicle (on the left side in this figure). The door inner panel61and the door outer panel62are welded together so as to have a closed-cross section formed thereby. A door trim is joined to a face of the door inner panel61which is opposite to the door outer panel62, which is not illustrated. The door panel portion60(the door inner panel61and the door outer panel62) closes the front-side opening portion3, and the peripheral part of the door panel portion60covering the front-side opening portion3overlaps with the vehicle-body frame member2in a vehicle side view (i.e., when viewed from the vehicle width direction).

The door inner panel61is made of a single-sheet steel plate. The door inner panel61is configured such that its peripheral part is positioned along a periphery of the front-side opening portion3(the vehicle-body frame member2) as shown inFIG. 3. The door inner panel61comprises an inner front portion63which extends in the vertical direction along the hinge pillar20, an inner rear portion64which extends in the vertical direction along a lower part of the center pillar40, and an inner lower portion65which extends along the side sill10and interconnects a lower-side end portion of the inner front portion63and a lower-side end portion of the inner rear portion64. The door inner panel61further comprises a beltline portion66which extends straightly in the longitudinal direction and interconnects an upper-side end portion of the inner front portion63and an upper-side end portion of the inner rear portion64. The door inner panel61further comprises a window frame portion67which forms a quarter-window opening portion which is closed with a window glass together with the beltline portion66.

In the vehicle side view (i.e., when viewed from the vehicle width direction), the inner front portion63overlaps with the hinge pillar20, the inner rear portion64overlaps with the center pillar40, the inner lower portion65overlaps with the side sill10, and the window frame portion67overlaps with the front pillar30and the roof side rail31.

The door inner panel61is provided with a curved wall portion68which is provided at an inside part of a corner portion which is positioned between the inner rear portion64and the inner lower portion65(i.e., a corner portion which is formed at a peripheral portion of the door inner panel61and corresponds to a connection portion of the side sill10and the center pillar40). This curved wall portion68is configured to be smoothly curved from the inner rear portion64toward the inner lower portion65in the vehicle side view (i.e., when viewed from the vehicle width direction) (seeFIGS. 3 and 9). That is, the curved wall portion68is curved forwardly and downwardly in the vehicle side view. Thus, the curved wall portion68is curved convexly toward an outside part of the corner portion positioned between the inner rear portion64and the inner lower portion65in the vehicle side view. The curved wall portion68extends in the vehicle width direction and in a peripheral direction of the peripheral portion of the door inner panel61.

The inner front portion63comprises, as shown inFIG. 5, a front-side outer wall portion63awhich is positioned at the outside, in a surface direction, of the door inner panel61(on the front side in this figure), a front-side inner wall portion63bwhich is positioned on the inside, in the surface direction, (on the rear side in this figure) of the front-side outer wall portion63a, and a front-side connection wall portion63cwhich interconnects the front-side outer wall portion63aand the front-side inner wall portion63bin the vehicle width direction. Herein, the surface direction of the door inner panel61(the surface direction of the door panel portion60) matches a surface direction of the front-side opening portion3.

The front-side outer wall portion63acomprises a part which expands in the longitudinal direction and in the vertical direction (which extends substantially along the surface direction of the front-side opening portion3) and another part which expands (extends) in the vehicle width direction and in the vertical direction continuously from a front-side end portion of the above-described part. The front-side inner wall portion63bexpands in the longitudinal direction and in the vertical direction. The front-side connection wall portion63cexpands in the vehicle width direction and in the vertical direction (extends in the vehicle width direction and in the peripheral direction of the peripheral portion of the door inner panel61) so as to interconnect a rear-side end portion of the front-side outer wall portion63aand a front-side end portion of the front-side inner wall portion63b. The front-side connection wall portion63cforms a ridgeline between the front-side outer wall portion63aand the front-side connection wall portion63c. The front-side outer wall portion63aextends in the vertical direction such that this portion63aoverlaps with the rear-side hinge-pillar flange24and the hinge-pillar side wall portion23cof the hinge pillar20in the vehicle side view (i.e., when viewed from the vehicle width direction). The front-side inner wall portion63bextends in the vertical direction such that this portion63boverlaps with the rear-side hinge-pillar flange24of the hinge pillar20in the vehicle side view (i.e., when viewed from the vehicle width direction).

The inner rear portion64comprises, as shown inFIG. 6, a rear-side outer wall portion64awhich is positioned at the outside, in the surface direction, of the door inner panel61(on the rear side in this figure), a rear-side inner wall portion64bwhich is positioned on the inside, in the surface direction, (on the front side in this figure) of the rear-side outer wall portion64a, and a rear-side connection wall portion64cwhich interconnects the rear-side outer wall portion64aand the rear-side inner wall portion64bin the vehicle width direction.

The rear-side outer wall portion64acomprises a part which expands in the longitudinal direction and in the vertical direction (which extends substantially along the surface direction of the front-side opening portion3) and another part which expands (extends) in the vehicle width direction and in the vertical direction continuously from a rear-side end portion of the above-described part. The rear-side inner wall portion64bexpands in the longitudinal direction and in the vertical direction. The rear-side connection wall portion64cexpands in the vehicle width direction and in the vertical direction (extends in the vehicle width direction and in the peripheral direction of the peripheral portion of the door inner panel61) so as to interconnect a front-side end portion of the rear-side outer wall portion64aand a rear-side end portion of the rear-side inner wall portion64b. A ridgeline is formed between the rear-side connection wall portion64cand the rear-side outer wall portion64a. The rear-side outer wall portion64aextends in the vertical direction such that this portion64aoverlaps with the front-side center-pillar flange45and the center-pillar side wall portion44cof the center pillar40in the vehicle side view (i.e., when viewed from the vehicle width direction). The rear-side inner wall portion64bextends in the vertical direction such that this portion64boverlaps with the front-side center-pillar flange45of the center pillar40in the vehicle side view (i.e., when viewed from the vehicle width direction).

An opening portion for exposing the striker42to a door inside (to a space between the door inner panel61and the door outer panel62) is provided at a part of the door-inner rear portion64which corresponds to the striker42. A door latch is provided at a position of this opening portion of the inner rear portion64, which is not illustrated. An engagement state of this door latch with the striker42is controlled by operating a door handle5a(seeFIG. 1).

The inner lower portion65comprises, as shown inFIG. 4, a lower-side outer wall portion65awhich is positioned at the outside, in the surface direction, of the door inner panel61(on the lower side in this figure), a lower-side inner wall portion65bwhich is positioned on the inside, in the surface direction, (on the upper side in this figure) of the lower-side outer wall portion65a, and a lower-side connection wall portion65cwhich interconnects the lower-side outer wall portion65aand the lower-side inner wall portion65bin the vehicle width direction.

The lower-side outer wall portion65aand the lower-side inner wall portion65bexpand in the longitudinal direction and in the vertical direction (which extends substantially along the surface direction of the front-side opening portion3). The lower-side connection wall portion65cexpands in the vehicle width direction and in the longitudinal direction (extends in the vehicle width direction and in the peripheral direction of the peripheral portion of the door inner panel61) so as to interconnect an upper-side end portion of the lower-side outer wall portion65aand a lower-side end portion of the lower-side inner wall portion65b. A ridgeline is formed between the lower-side connection wall portion65cand the lower-side outer wall portion65a. The lower-side outer wall portion65aextends in the longitudinal direction such that this portion65aoverlaps with the upper-side side-sill flange13and the side-sill side wall portion12cof the side sill10in the vehicle side view (i.e., when viewed from the vehicle width direction). The lower-side inner wall portion65bextends in the longitudinal direction such that this portion65boverlaps with the upper-side side-sill flange13of the side sill10in the vehicle side view (i.e., when viewed from the vehicle width direction).

The rear-side connection wall portion64cand the lower-side connection wall portion65care smoothly connected by the curved wall portion68, and the front-side connection wall portion63cand the lower-side connection wall portion65care smoothly connected by the above-described front-lower curved wall portion provided at the inside part of the corner portion positioned between the inner front portion63and the inner lower portion65.

The window frame portion67comprises, as shown inFIG. 7, an upper-side outer wall portion67awhich is positioned at the outside, in the surface direction, of the door inner panel61(on the upper side in this figure), an upper-side inner wall portion67bwhich is positioned on the inside, in the surface direction, of the door inner panel61(on the lower side in this figure) relative to the upper-side outer wall portion67a, and an upper-side connection wall portion67cwhich interconnects the upper-side outer wall portion67aand the upper-side inner wall portion67bin the vertical direction and in the vehicle width direction. The upper-side outer wall portion67aexpands in the longitudinal direction and in the vehicle width direction and slants downwardly toward the right side. The upper-side inner wall portion67bexpands in the longitudinal direction and in the vertical direction. The lower-side connection wall portion65cis curved downwardly toward the left side from a right-side end portion of the upper-side outer wall portion67aso as to interconnect a right-side end portion of the upper-side outer wall portion67aand an upper-side end portion of the upper-side inner wall portion67b. The upper-side outer wall portion67aand the upper-side connection portion67cextend such that they overlap with the roof-side flange34in the vehicle sideview (i.e., when viewed from the vehicle width direction).

As shown inFIG. 3, a first impact bar81which is made of a plate member and a second impact bar82are attached to the door inner panel61. The first impact bar81extends obliquely rearwardly-and-downwardly and interconnects an upper-side end portion of the inner front portion63and a lower-side end portion of the inner rear portion64. The second impact bar82extends obliquely rearwardly-and-downwardly so as to interconnect a middle part, in the longitudinal direction, of the beltline portion66and a middle part, in the vertical direction, of the inner rear portion64. The first impact bar81is configured such that both-side end portions, in the longitudinal direction, thereof have a hat-shaped cross section and a middle portion, in the longitudinal direction, thereof has an M-shaped cross section as shown inFIGS. 4 and 6.

As shown inFIGS. 3-8, plural reinforcement portions are provided at the peripheral portion of the door inner panel61, wherein the peripheral portion of the door inner panel61is reinforced by the reinforcement portions against a collision load which is inputted (applied) to the front side door5from an outward side, in the vehicle width direction, of the front side door5. Specifically, the reinforcement portions include a front-side reinforcement portion71which is provided along the inner front portion63, a rear-side reinforcement portion72which is provided along the inner rear portion64, a lower-side reinforcement portion73which is provided along the inner lower portion65, and an upper-side reinforcement portion74which is provided at the window frame portion67. The reinforcement portions71-74may be made of a plate member, which is made from hot material, for example.

The front-side reinforcement portion71is, as shown inFIG. 3, a patch member which is attached along the front-side outer wall portion63a, the front-side inner wall portion63b, and the front-side connection wall portion63c. That is, the front-side reinforcement portion71is provided to straddle a ridgeline between the front-side outer wall portion63aand the front-side connection wall portion63c, whereby the inner front portion63(particularly, the front-side connection wall portion63c) is reinforced against the collision load.

The front-side reinforcement portion71is, as shown inFIG. 5, provided to overlap with the hinge-pillar side wall portion23cof the hinge pillar20in the vehicle side view (i.e., when viewed from the vehicle width direction). Further, the front-side reinforcement portion71is provided substantially over an entire part of the inner front portion63, including a portion of the peripheral portion of the door inner panel61(an upper part of the inner front portion63) which corresponds to the instrument-panel member26. That is, the front-side reinforcement portion71is provided at the peripheral portion of the door inner panel61so as to overlap with the instrument-panel member26in the vehicle side view (i.e., when viewed from the vehicle width direction).

The front-side reinforcement portion71is provided to overlap with an upper-side end portion of the first impact bar81in the vehicle side view (i.e., when viewed from the vehicle width direction) as shown inFIGS. 3 and 8. The front-side reinforcement portion71is welded to the inner front portion63in a state where this portion71overlaps with the first impact bar81and the inner front portion63(specifically, the front-side outer wall portion63a) at a joint position of the first impact bar81to the door inner panel61, which is not illustrated.

The rear-side reinforcement portion72is a patch member which is attached along the rear-side outer wall portion64a, the rear-side connection wall portion64c, the curved wall portion68, and a corner portion positioned between the rear-side outer wall portion64aand the lower-side outer wall65aas shown inFIGS. 3, 6 and 9. That is, the rear-side reinforcement portion72is provided to straddle a ridgeline between the rear-side outer wall portion64aand the rear-side connection wall portion64cand a ridgeline between the curved wall portion68and the above-described corner portion, whereby the inner rear portion64(particularly, the rear-side connection wall portion64c) and the corner portion positioned between the inner rear portion64and the inner lower portion65(particularly, the curved wall portion68) are reinforced against the above-described collision load.

The rear-side reinforcement portion72is, as shown inFIG. 6, provided to overlap with the front-side center-pillar flange45and the center-pillar-side wall portion44cof the center pillar40in the vehicle side view (i.e., when viewed from the vehicle width direction). The rear-side reinforcement portion72is provided at a lower-side part of the inner rear portion64and the corner portion positioned between the inner rear portion64and the inner lower65of the peripheral portion of the door inner panel61. A portion of the rear-side reinforcement portion72which corresponds to the above-described corner portion (a front-side lower portion of the rear-side reinforcement portion72) is provided at a portion of the peripheral portion of the door inner panel61which corresponds to the second floor cross member47. That is, the front-side lower portion of the rear-side reinforcement portion72is located substantially at the same position, in the longitudinal direction, as the second floor cross member47.

The rear-side reinforcement portion72is, as shown inFIGS. 3 and 8, provided to overlap with a lower-side end portion of the first impact bar81in the vehicle side view (i.e., when viewed from the vehicle width direction). The lower-side end portion of the first impact bar81is fixed to the corner portion positioned between the inner rear portion64and the inner lower portion65(i.e., the corner portion which is formed at the peripheral portion of the door inner panel61and corresponds to a connection portion of the side sill10and the center pillar40). The rear-side reinforcement portion72is welded to the inner rear portion64in a state where this portion72overlaps with the first impact bar81and the inner rear portion64(specifically, the rear-side outer wall portion64a) at a joint position of the first impact bar81to the door inner panel61, which is not illustrated.

As shown inFIG. 9, the rear-side reinforcement portion72is provided with a rear-side curved portion72aat an inside part of the corner portion positioned between the inner rear portion64and the inner lower portion65where the rear-side reinforcement portion72is provided. This curved portion72ais configured to be curved convexly toward an outside part of the above-described corner portion in the vehicle side view (i.e., when viewed from the vehicle width direction). The curved portion72aextends along the above-described curved wall portion68and is fixed to this curved wall portion68. That is, the rear-side curved portion72aextends in the vehicle width direction and in the peripheral direction of the peripheral portion of the door inner panel61as well as the curved wall portion68. The curved portion72ais continuous to a portion of the rear-side reinforcement portion72which is attached and fixed to the rear-side connection wall portion64c.

The lower-side reinforcement portion73is, as shown inFIG. 4, configured to have a U-shaped cross section which is opened to the right side and to form a closed-cross section cooperatively with the side sill10. Specifically, the lower-side reinforcement portion73is joined to the lower-side outer wall portion65aand the lower-side connection wall portion65csuch that this portion73straddles the ridgeline between the lower-side outer wall portion65aand the lower-side connection wall portion65cand thereby the closed-cross section is formed. Thereby, the lower-side reinforcement portion73reinforces the inner lower portion65(particularly, the lower-side connection portion65c) against the above-described collision load.

The lower-side reinforcement portion73is provided to overlap with the upper-side side-sill flange13and the side-sill side wall portion12cof the side sill10in the vehicle side view (i.e., when viewed from the vehicle width direction). Further, the lower-side reinforcement portion73is provided over a nearly entire part of the inner lower portion65(except a portion near its rear end), including a portion of the peripheral portion of the door inner panel61which corresponds to the first floor cross member17(a central portion, in the longitudinal direction, of the inner lower portion65). That is, the lower-side reinforcement portion73is provided at the peripheral portion of the door inner panel61so as to overlap with the first floor cross member17in the vehicle side view (i.e., when viewed from the vehicle width direction).

The upper-side reinforcement portion74is a patch member which is attached along a left-side face of the upper-side connection wall portion67cof the window frame portion67as shown inFIG. 7, and this reinforcement portion74reinforces the window frame portion67(particularly, the upper-side outer wall portion67aand the upper-side connection wall portion67c) against the collision load. The upper-side reinforcement portion74is provided to overlap with the roof-side flange34of the roof-side outer panel33in the vehicle side view (i.e., when viewed from the vehicle width direction). Further, the upper-side reinforcement portion74is provided at a portion of the peripheral portion of the door inner panel61which includes a portion corresponding to the roof cross member36. That is, the upper-side reinforcement portion74is provided at the peripheral portion of the door inner panel61such that at least a part of the upper-side reinforcement portion74is located substantially at the same position, in the longitudinal direction, as the roof cross member36.

The door outer panel62is made by processing a sheet of steel plate similarly to the door inner panel61. The door outer panel62determines an outer shape (contour) of the front side door5, when viewed from an outward side, in the vehicle width direction, of the vehicle1as shown inFIG. 1.

Herein, the rear side door6also comprises, similarly to the front side door5, a door panel portion which is configured to close the rear-side opening portion4and such that its peripheral part overlaps with the vehicle-body frame member2(the side sill10, the roof side rail31, the center pillar40, the wheel arch50, and the quarter pillar51) in the vehicle side view and plural reinforcement portions which are provided at a peripheral part of the door panel portion (at a peripheral part of its door inner panel, for example) so as to reinforce this peripheral part against a collision load inputted (applied) to the rear side door6from the vehicle outward side. These reinforcement portions are provided at respective portions of the peripheral part of the door panel portion of the rear side door6which overlap with the center pillar40, the wheel arch50, the side sill10, and the roof side rail31in the vehicle side view (i.e., when viewed from the vehicle width direction).

The reinforcement portion provided at the portion of the peripheral part of the door panel portion of the rear side door6so as to overlap with the side sill10in the vehicle side view is provided to overlap with a third floor cross member which extends in the vehicle width direction in back of the second floor cross member47in the vehicle side view.

The reinforcement portion provided at the portion of the peripheral part of the door panel portion of the rear side door6so as to overlap with the wheel arch50in the vehicle side view is provided to overlap with a cross member which extends in the vehicle width direction and interconnects right-and-left rear side frames in the vehicle side view.

The reinforcement portion provided at the portion of the peripheral part of the door panel portion of the rear side door6so as to overlap with the roof side rail31in the vehicle side view is provided such that at least a part of this reinforcement portion is located substantially at the same position, in the longitudinal direction, as a roof cross member which extends in the vehicle width direction in back of the roof cross member36.

Herein, the vehicle-body structure of the vehicle1is required to suppress the center pillar40from coming into the cabin as much as possible in the vehicle side view. In the case where the first and second impact bars81,82are provided like the present embodiment, the collision load of the vehicle side collision can be absorbed to a certain degree by these impact bars81,82. However, since the vehicle-body frame member2receives the load transmitted from the impact bars81,82at a point, there is a concern that the efficiency of the collision-load transmission to the vehicle-body frame member2may be low.

If a door frame member (a member having a closed-cross section, for example) is arranged between the door inner panel61and the door outer panel62like a conventional side door, the transmission efficiency of the collision load may be improved. However, since the weight reduction of the vehicle1is recently required from viewpoints of the fuel efficiency and the like, it is preferable that no door frame member be arranged.

Herein, according to the present embodiment of the invention, buckling deformation of the door inner panel61is so suppressed in the vehicle side collision by providing the reinforcement portions71-74at the peripheral part of the door inner panel61(particularly, at the portion which includes a part corresponding to the vehicle-width-direction-extending vehicle-body frame member in the vehicle side view) as described above that the collision load can be efficiently transmitted to the vehicle-body frame member2. Further, the collision load can be efficiently transmitted to the vehicle-width-direction-extending vehicle-body frame member.

Hereafter, a motion of the door panel portion60in the vehicle side collision will be described referring to an example of the vehicle side collision shown inFIGS. 10-14. Herein,FIGS. 10-14show a case where a collision object A collides with the left-side part of the vehicle1. Further,FIGS. 10-14show the motion of the door panel portion60of the front side door5, omitting illustration of a motion regarding the rear side door6.

A situation where the collision object A (another vehicle, for example) moves toward the center pillar40and then contacts the left-side part of the vehicle1as shown inFIG. 10is assumed here. Herein, the inner rear portion64is in a state where it is interposed between the center pillar40and the collision object A.

When the collision object A comes in as shown inFIG. 11from the state shown inFIG. 10, a load directed to a cabin inside (to the right side in this figure) is inputted (applied). Herein, the front side door5is moved (pushed) to the right side and deformed such that its rear side is positioned at the right side. Accordingly, as shown inFIG. 11, the inner front portion63and the rear-side hinge-pillar flange24of the hinge pillar20come to contact each other, and the inner rear portion64and the front-side center-pillar flange45of the center pillar40come to contact each other. At this moment, the inner front portion63transmits the collision load to the hinge pillar20and also receives a reaction load from the hinge pillar20. Further, the inner front portion63receives a force directed to the inside, in the surface direction, of the door inner panel61(to the rear side in this figure) through this coming-in of the collision object A. Meanwhile, the inner rear portion64transmits the collision load to the center pillar40and also receives a reaction load from the center pillar40.

Further, as shown inFIG. 12, the inner lower portion65comes to contact the upper-side side-sill flange13and the side-sill side wall portion12cof the side sill10. Accordingly, the inner lower portion65transmits the collision load to the side sill10and also receives a reaction force from the side sill10. Further, the inner lower portion65receives the force directed to the inside, in the surface direction, of the door inner panel61(to the upper side in this figure) through the coming-in of the collision object A.

Also, the widow frame portion67comes to contact the roof side rail31, which is not illustrated. Accordingly, the widow frame portion67transmits the collision load to the roof side rail31and also receives a reaction force from the roof side rail31. Further, the roof side rail31receives the force directed to the inside, in the surface direction, of the door inner panel61(to the lower side in this figure) through the coming-in of the collision object A.

A situation where the collision object A further comes to the right side from the state ofFIG. 11as shown inFIG. 13is assumed here. The inner front portion63is suppressed from being deformed by the front-side reinforcement portion71. Particularly, the front-side reinforcement portion71suppresses the front-side outer wall portion63afrom being rotated (rotational deformation) to the inside, in the surface direction, of the door inner panel61with a support point of the ridgeline between the front-side outer wall portion63aand the front-side connection wall portion63cand also suppresses the front-side connection wall portion63cfrom being bent (bucking deformation) to the inside, in the surface direction, of the door inner panel61. Thereby, the inner front portion63maintains its contact state (or its connection state) with the hinge pillar20, without coming into the cabin at a position right behind the hinge pillar20. Meanwhile, in this example of the vehicle side collision, since the inner rear portion64is interposed between the collision object A and the center pillar40in this collision situation, a contact state (or a connection state) of the inner rear portion64and the center pillar40is maintained. Thus, the transmission of the collision load from the inner front portion63to the hinge pillar20can be maintained and also the transmission of the collision load from the inner rear portion64to the center pillar40can be maintained.

As described above, since the front-side reinforcement portion71overlaps with the instrument-panel member26in the vehicle side view (i.e., when viewed from the vehicle width direction), the collision load of the vehicle side collision is transmitted from the door inner panel61(the portion where the front-side reinforcement portion71is provided) to the instrument-panel member26by way of the hinge pillar20. Since it is the vehicle-body frame member extending in the vehicle width direction, the instrument-panel member26can receive the collision load properly. Further, since the front-side lower portion of the rear-side reinforcement portion72is located substantially at the same position, in the vehicle longitudinal direction, as the second floor cross member47as described above, the collision load of the vehicle side collision is transmitted from the door inner panel61(the portion where the rear-side reinforcement portion72is provided) to the second floor cross member47by way of the center pillar47and the side sill10. Herein, since it is the vehicle-width-direction-extending vehicle-body frame member extending in the vehicle width direction, the second floor cross member47can receive the collision load properly.

Further, as shown inFIG. 14, it is suppressed by the lower-side reinforcement portion73that the inner lower portion65is deformed in such a manner that this inner lower portion65rides over the side sill10. Particularly, the lower-side reinforcement portion73suppresses the lower-side outer wall portion63afrom being rotated (rotational deformation) to the inside, in the surface direction, of the door inner panel61with a support point of the ridgeline between the lower-side outer wall portion63aand the lower-side connection wall portion65cand also suppresses the lower-side connection wall portion65cfrom being bent (buckling deformation) to the inside, in the surface direction, of the door inner panel61. Thereby, the inner lower portion65maintains its contact state (or its connection state) with the side sill10, without coming into the cabin at a position right above the side sill10. Consequently, the transmission of the collision load from the inner lower portion65to the side sill10can be maintained.

As described above, since the lower-side reinforcement portion73overlaps with the first floor cross member17in the vehicle side view (i.e., when viewed from the vehicle width direction), the collision load of the vehicle side collision is transmitted from the door inner panel61(the portion where the lower-side reinforcement portion73is provided) to the first floor cross member17by way of the side sill10. Since it is the vehicle-width-direction-extending vehicle-body frame member extending in the vehicle width direction, the first floor cross member17can receive the collision load properly.

Further, the upper-side outer wall portion67aand the upper-side connection wall portion67cof the window frame portion67are suppressed from having buckling deformation by the upper-side reinforcement portion74, which is not illustrated. Thereby, the contact state (or the connection state) of the window frame portion67and the roof side rail31is maintained, without coming into the cabin at a position right below the roof side rail31. Consequently, the transmission of the collision load from the window frame portion67to the rood side rail31can be maintained.

Since at least part of the upper-side reinforcement portion74is located substantially at the same position, in the vehicle longitudinal direction, as the roof cross member36at the peripheral portion (upper portion) of the door inner panel61as described above, the collision load of the vehicle side collision is transmitted from the door inner panel61(the portion where the upper-side reinforcement portion74is provided) to the roof cross member36by way of the roof side rail31. Since it is the vehicle-width-direction-extending vehicle-body frame member extending in the vehicle width direction, the roof cross member36can receive the collision load properly.

As described above, the collision load of the vehicle side collision is transmitted from the front side door5to the vehicle-body frame member2, being dispersed to the peripheral part of the door panel portion60, by maintaining the contact state of the peripheral part of the door panel portion60of the front side door5and the vehicle-body frame member2in the vehicle side collision. Further, the collision load of the vehicle side collision is properly transmitted to the vehicle-width-direction-extending vehicle-body frame member (the instrument-panel member26, the first floor cross member17, the second floor cross member47, and the roof cross member36). This situation also happens to the rear side door6similarly. Thus, the amount of absorption of the collision load of the vehicle side collision can be increased.

Meanwhile, it is unnecessary that the plate thickness of the first impact bar81and the second impact bar82is made thick or these bars are made of a frame member having a closed-cross section in order to increase the amount of absorption of the collision load in the vehicle side collision. It is also unnecessary that the number of impact bar is increased or a new impact bar is added. Consequently, the weight reduction of the front side door5can be attained. The weight reduction of the rear side door6can be attained as well.

Accordingly, the weight reduction of the vehicle1and increasing of the amount of absorption of the collision load in the vehicle side collision can be compatibly attained.

The present invention should not be limited to the above-described embodiment and any other modifications or improvements may be applied within the scope of a spirit of the present invention.

For example, while the reinforcement portions71-74are provided at the door inner panel61in the above-described embodiment, these portions may be provided at a portion of a peripheral portion of the door outer panel62as the door panel portion60which includes a part corresponding to the vehicle-width-direction-extending vehicle-body frame member. Even in a case where the reinforcement portions71-74are provided at the door outer panel62, it is suppressed that the side door is pushed into the cabin in the vehicle side collision, so that a contact state of the door outer panel62and the vehicle-body frame member2is maintained like the above-described embodiment.

Further, while the case where the contact state of the door inner panel61and the vehicle-body frame member2is maintained in the vehicle side collision is described in the above-described embodiment, an engagement state of the door panel portion60and the vehicle-body frame member2may be maintained by providing catcher pins as the reinforcement portions71-74.

Moreover, while the door inner panel61(the inner lower portion65) forms the closed-cross section together with only the lower-side reinforcement portion73in the above-described embodiment, the front-side reinforcement portion71, the rear-side reinforcement portion72, or the upper-side reinforcement portion74may form a closed-cross section together with the door inner panel61. On the contrary, the lower-side reinforcement portion73may be a patch member attached along the wall portions of the door inner panel61, similarly to the front-side reinforcement portion71and so on.

Also, a part or a whole part of the reinforcement portions71-74may not be configured to be a separate member from the door inner panel61. In this case, the reinforcement portions71-74can be configured by making the plate thickness of a portion of the door inner panel61which corresponds to the reinforcement portions71-74thicker than the other part of the door inner panel61, for example.

Further, while the reinforcement portions are the front-side reinforcement portion71, the rear-side reinforcement portion72, the lower-side reinforcement portion73, and the upper-side reinforcement portion74in the above-described embodiment, the front-side reinforcement portion71and the upper-side reinforcement portion74may be omitted as long as the rear-side reinforcement portion72and the lower-side reinforcement portion73are provided at the portions of the peripheral part of the door panel portion which include the parts corresponding to the vehicle-width-direction-extending vehicle-body frame member (the second floor cross member47and the first floor cross member17). In this case, it is preferable that the rear-side reinforcement portion72be configured to extend in the vertical direction as long as possible and the lower-side reinforcement portion73be configured to extend in the longitudinal direction as long as possible. Alternatively, the front-side reinforcement portion71and the lower-side reinforcement portion74may be provided only as the reinforcement portion and these portions71,73may be provided at the portions of the peripheral part of the door panel portion which include the parts corresponding to the vehicle-width-direction-extending vehicle-body frame member (the instrument-panel member26and the first floor cross member17). Further, the front-side reinforcement portion71, the rear-side reinforcement portion72, and the lower-side reinforcement portion73may be provided only as the reinforcement portion and these portions71,72,73may be provided at the portions of the peripheral part of the door panel portion which include the parts corresponding to the vehicle-width-direction-extending vehicle-body frame member (the instrument-panel member26, the second floor cross member47, and the first floor cross member17).

Moreover, it is possible that at least two reinforcement portions among the front-side reinforcement portion71, the rear-side reinforcement portion72, the lower-side reinforcement portion73, and the upper-side reinforcement portion74are formed integrally. For example, the front-side reinforcement portion71and the lower-side reinforcement portion73, the rear-side reinforcement portion72and the lower-side reinforcement portion73, or the front-side reinforcement portion71, the rear-side reinforcement portion72and the lower-side reinforcement portion73may be respectively formed integrally. These integrated reinforcement portions can be regarded as a single reinforcement portion.