Rear structure of vehicle body

The present invention is to provide a rear structure of a vehicle body that can ensure high body stiffness and suspension stiffness and that can disperse impact load to the whole body. In the rear structure of a vehicle body, a crossmember 20 bridged between right and left rear side frames 1, 5 is approximately an X-shape in plan view having a first crossmember 21 and a second crossmember 22, and at least one of the front ends of the first and second crossmembers and the rear ends of the first and second crossmembers is directly connected to a structure to be equipped with a suspension.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rear structure of a vehicle body, particularly the rear structure ensuring stiffness of the body and stiffness supporting suspension.

2. Description of the Related Art

In a lower structure of a vehicle body positioned in a rear portion of a body of a vehicle, as shown inFIG. 16illustrating a plan view of the principal portion of the structure, right and left rear side frames102whose front portions are each connected to rear portions of right and left side sills101extending along right and left sides of the vehicle body and which extend in a body fore-and-aft direction are disposed, and a frontward crossmember103and a backward crossmember104extending in a width direction of the body are disposed between the right and left rear side frames102to form a frame in the form of an approximate ladder.

JP-A-08-142909 describes, at columns 0026 to 0031 andFIG. 1, a rear body structure shown inFIG. 17illustrating a plan view of a principal portion of the rear body structure. In the rear body structure, a front crossmember106and a rear crossmember107extending in the width direction of the body are bridged between the front ends of the right and left rear side frames105and between the intermediate positions of the frames, respectively, the portions adjacent to the ends of the rear crossmember107are connected to the rear side frames105through auxiliary members108. Further, brackets109are attached to an approximate triangle area surrounded by these rear side frames105and the auxiliary members108, and shock absorbers110of a rear suspension are attached to this bracket109.

JP-A-09-118252 describes, at columns 0034 to 0039 andFIG. 29, a rear body structure shown inFIG. 18illustrating a plan view of a principal portion of the rear body structure. In the rear body structure, a front backward crossmember112and a rear backward crossmember113extending in the width direction of the body are bridged between right and left rear side frames111, and a central portion of the front rear crossmember112is connected to a rear end of a tunnel top reinforce114forming a closed cross section extending in a fore-and-aft direction together with a tunnel portion. Further, a pair of diagonal members115is disposed between the front backward crossmember112and the rear backward crossmember113by connecting the front ends of the diagonal members to a connecting portion of the front backward crossmember112and the tunnel top reinforce114and connecting the rear ends of the diagonal members to the rear portion111aof the side frame111.

SUMMARY OF THE INVENTION

According to the lower structure of a vehicle body shown inFIG. 16, the frontward crossmember103and the backward crossmember104extending in the width direction of the body are bridged between the right and left rear side frames102, and therefore relative connecting stiffness between the right and left rear side frames102can not be sufficiently obtained. Hence, vibration or torsion of the vehicle body generated when the vehicle is running causes relative deformation of the right and left rear side frames102as shown in a virtual line ofFIG. 16to occasionally reduce drivability and driving stability.

Further, the frontward crossmember103and the backward crossmember104extending in the width direction of the body are frequently formed in curved or bent shape to avoid contact with a fuel tank, a suspension member or a spare tire. Thus, in case impact load is applied to the body from its side or its rear, the impact load can not be efficiently dispersed and transmitted from the one of the rear side frames102to the other of the frames, whereby it occasionally makes impossible to disperse effectively the impact load to the whole body.

In the rear structure of the body ofFIG. 17, stiffness supporting the suspension can be enhanced by attaching the shock absorbers110of rear suspension to the brackets109attached to an approximate triangle area surrounded by these rear side frames105, the rear crossmember107and the auxiliary members108. However, vibration or torsion of the vehicle body generated when the vehicle is running causes relative deformation of the right and left rear side frames105in the same manner as inFIG. 16to occasionally reduce operation performance and driving stability. Further, the frontward crossmember106and the backward crossmember107are extended in the width direction of the body to be disposed between the right and left rear side frames105, and therefore in case impact load is applied to the body from its side or rear, the impact load can not be efficiently dispersed and transmitted from the one of the rear side frames105to the other of the frames105, whereby it occasionally makes impossible to disperse effectively the impact load throughout the body.

Further, in the rear body structure ofFIG. 18, stiffness of the body can be enhanced by disposing the pair of diagonal members115between the frontward crossmember112and the backward crossmember113extending in the width direction of the body and disposed between right and left rear side frames111. However, the disposition of the frontward crossmember112, the backward crossmember113and the pair of diagonal members115therebetween brings about complexation of each of the members and increase of the body weight. Moreover, the frontward crossmember112, the backward crossmember113and the diagonal members115each occupy a large area for disposing them to restrict freedom for vehicle body design.

Moreover, to ensure good drivability and driving stability, high suspension-supporting-stiffness for supporting a suspension to body members is required.

Hence, in view of the above-mentioned problems, the object of the present invention is to provide a rear structure of a vehicle body (generally car body) that can ensure high body stiffness and suspension-supporting-stiffness without bringing about complexation of the structure and increase of the body weight, and that can disperse impact load to to the whole body.

The present invention (first invention) to attain the object is provided by a rear structure of a vehicle body provided with right and left rear side frames disposed on right and left sides of the body and extending in the fore-and-aft direction of the body, and crossmembers bridged between the right and left rear side frames;the crossmembers being approximately an X-shape in plan view and comprising a first crossmember and a second crossmember,the first crossmember having a front end connected to one of the rear side frames and a rear end connected to the other of the rear side frames, and extending in the rear direction of the body from the front end to the rear end while receding from one of the rear side frames,the second crossmember having a front end connected to the other of the rear side frames and a rear end connected to one of the rear side frames, and extending in the rear direction of the body from the front end to the rear end while receding from the other of the rear side frames and intersecting with the first crossmember to be connected to one of the rear side frames;wherein at least one of the front ends of the first and second crossmembers and the rear ends of the first and second crossmembers is connected to the rear side frames in the vicinity of a structure to be equipped with a suspension.

According to the first invention, the approximately X-shaped crossmembers comprising a first crossmember and a second crossmember are bridged between the right and left rear side frames while at least one of the front ends of the first and second crossmembers and the rear ends of the first and second crossmembers is connected to the rear side frames in vicinity of a structure to be equipped with a suspension. Therefore, the first and second crossmembers suppress relative deformation of the right and left rear side frames to give high stiffness of the rear portion of the body and to enhance stiffness for supporting the suspension. Further, if impact load is applied to the body from its side or its rear, the impact load can be dispersed efficiently from the one of the rear side frames to the other of the frames through the approximately X-shaped crossmembers, whereby the impact load can be dispersed and transmitted to the whole body.

Further, the simple structure obtained by intersecting the first and second crossmembers to bridge between the right and left rear side frames can bring about improvement of the body stiffness and the stiffness for supporting a suspension and reduction of body weight.

The present invention (second invention) to attain the object is provided by a rear structure of a vehicle body provided with a pair of right and left rear side frames disposed on right and left sides of the body and extending in the fore-and-aft direction of the body, and crossmembers bridged between the right and left rear side frames;

the crossmembers being approximately an X-shape in plan view and comprising a first crossmember and a second crossmember,

the first crossmember having a front end connected to one of the rear side frames and a rear end connected to the other of the rear side frames, and extending in the rear direction of the body from the front end to the rear end while receding from one of the rear side frames,

the second crossmember having a front end connected to the other of the rear side frames and a rear end connected to one of the rear side frames, and extending in the rear direction of the body from the front end to the rear end while receding from the other of the rear side frames and intersecting with the first crossmember to be connected to one of the rear side frames;

wherein at least one of the front ends of the first and second crossmembers and the rear ends of the first and second crossmembers is directly connected to a structure to be equipped with a suspension.

According to the second invention, the approximately X-shaped crossmembers comprising a first crossmember and a second crossmember are bridged between the right and left rear side frames while at least one of the front ends of the first and second crossmembers is directly connected to a structure to be equipped with a suspension. Therefore, the first and second crossmembers suppress relative deformation of the right and left rear side frames to give high stiffness of the rear portion of the body and to enhance stiffness for supporting the suspension. Further, if impact load is applied to the body from its side or its rear, the impact load can be dispersed efficiently from the one of the rear side frames to the other of the frames through the X-shaped crossmembers, whereby the impact load can be dispersed and transmitted to the whole body.

Further, the simple structure obtained by intersecting the first and second crossmembers to bridge between the right and left rear side frames and by directly connecting the first and second crossmembers to a structure to be equipped with a suspension can bring about improvement of the body stiffness and the stiffness for supporting suspension and reduction of body weight.

The preferred embodiment (1) of the first and second inventions is provided by the rear structure of vehicle body wherein the structure to be equipped with a suspension is connected to the crossmember within the rear side frames.

According to the preferred embodiment (1), since the structure to be equipped with a suspension is connected to the crossmember within the rear side frames, the structure can be formed in compact within the rear side frames to reduce the space occupied by the structure whereby freedom for body design is ensured.

The preferred embodiment (2) of the first and second inventions is provided by the rear structure of a vehicle body wherein the structure to be equipped with a suspension is a pipe disposed within the rear side frames and attached to a member of the suspension to support it.

The preferred embodiment (2) is corresponded to an example of the preferred embodiment (1). According to the preferred embodiment (2), since the pipe to be equipped with a suspension is connected and supported to the rear side frames and the member of the suspension, the stiffness for supporting a suspension can be more improved.

The preferred embodiment (3) of the first and second inventions is provided by the rear structure of a vehicle body wherein the vehicle body has right and left C-pillars (rear pillars) extending in the vertical direction of the body, and the front ends of the first and second crossmembers are extended (and disposed) to the lower ends of the C-pillars.

According to the preferred embodiment (3), since the front ends of the first and second crossmembers are extended and disposed to the lower ends of the C-pillars, the connecting stiffness (bonding stiffness) between the lower portion of the body and the C-pillars are greatly improved to enhance stiffness of the body. Further, if impact load is applied to the body from its side or its rear, the impact load can be dispersed and transmitted to the whole lower portion of the body through the right and left rear side frames and the first and second crossmembers and simultaneously dispersed efficiently to the C-pillars, whereby the impact load can be also dispersed to the sides and the upper portion of the body to permit the impact load to efficiently disperse to the whole body.

The preferred embodiment (4) of the first and second inventions is provided by the rear structure of vehicle body wherein the vehicle body has right and left D-pillars (pillars to the rear of C-pillars) extending in the vertical direction of the body, and the rear ends of the first and second crossmembers are extended (and disposed) to the lower ends of the D-pillars to be disposed on the ends.

According to the preferred embodiment (4), because the rear ends of the first and second crossmembers each are extended to the lower ends of the right and left D-pillars, the high connecting stiffness between the lower portion of the body and D-pillars are ensured to greatly improve the stiffness of the body. Further, if impact load is applied to the body from its side or its rear, the impact load can be dispersed and transmitted to the whole lower portion of the body through the right and left rear side frames and the first and second crossmembers and simultaneously dispersed efficiently to the D-pillars, whereby the impact load can be dispersed from the D-pillars to the sides and the upper portion of the body to permit the impact load to efficiently disperse to the whole body.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the rear structure of a vehicle body according to the present invention are explained by reference of the drawings.

First Embodiment

FIG. 1is a perspective view showing schematically a first embodiment of the rear structure of vehicle body according to the present invention. InFIG. 1, an arrow F represents a front of the body and an arrow W represents a width of the body.

Examples of the vehicle (i.e., automobile) include a wagon type automobile in which a passenger room and a luggage room disposed in rear side of the passenger room are incorporated. In the automobile, side sills (not shown) are disposed opposite to each other along the right and left sides of the body in the lower portion of the rear body, and the front portions of the right and left rear side frames1,5extending in the fore-and-aft direction of the body are connected to the rear portions of the side sills, respectively.

Right and left side rails11,12are extended along the both sides of a lower surface of a roof panel10on the upper side of the body positioned in the upper side of the rear portion of the vehicle body, while right and left C-pillars13,14extending in a vertical direction along a rear side of an opening of a rear door and right and left D-pillars15,16extending in a vertical direction along a rear end of the body are formed in the right and left sides of the body. Further, the upper ends of the C-pillars13,14are connected directly to the side rails11,12, and the lower ends are connected directly to the rear side frames1,5or connected to the frames through floor panels etc. (inFIG. 1, the C-pillars13,14and D-pillars15,16are hatched). The upper ends of the D-pillars15,16are connected to the rear ends of the side rails11,12, respectively, while the lower ends of the D-pillars are connected to the rear side frames1,5through the floor panel, a reinforce etc.

The rear side frame1is, as shown inFIG. 2illustrating a section view taken along I—I line ofFIG. 1, has a closed section view in the form of an approximate rectangle (hollow) which is formed from an inner panel2and an outer panel3. The inner panel2extends in the fore-and-aft direction in the form of approximate “U” in section view and which has an upper surface2band a lower surface2cbent outwardly in the width direction of the body along an inner surface2aand its upper and lower edges, and the outer panel3is in the form of an approximate plane plate of which upper edge and lower edge are connected to each of flanges2d,2eformed by bending outwardly edges of an upper surface2band lower surface2cof an inner panel2. Further, the rear side frame5also has a closed section view in the form of an approximate rectangle (hollow) which extends in the fore-and-aft direction of the body and which is formed from an inner panel6bent and formed in the form of approximate “U” in section view having an inner surface6a, an upper surface6band a lower surface6c, and from the outer panel7in the form of plane plate.

The right and left rear side frames1and5are connected to each other by the front crossmember8extending in the width direction of the body, and the rear ends1aand5aof the frames are connected to each other by a rear skirt19and bumper beam (not shown) extending in the width direction of the body.

Further, a first crossmember21is obliquely bridged between the right and left rear side frames1and5. The first crossmember21has a front end21aconnected to one rear side frame1and a rear end21bconnected to the other rear side frame5, and extends in the form of linear line in the rear direction of the body with moving from the rear side frame1to the rear side frame5. The second crossmember22is also bridged between the right and left rear side frames1and5. The second crossmember22has a front end22aconnected to the rear side frame5and a rear end22bconnected to the rear side frame1, and extends in the form of linear line in the rear direction of the body with moving from the rear side frame1to the rear side frame5to intersect the first crossmember21at the middle position of the rear side frame5.

These first and second crossmembers21,22are in the form of cylinder, and connected each other at an intersecting portion23to form a crossmember20in the form of “X” in plan view.

As shownFIG. 3illustrating a perspective view shown by magnifying A portion of FIG.1andFIG. 4illustrating a section view taken along II—II line ofFIG. 3, the intersecting portion23is formed by compressing the intersecting portion of the first and second crossmembers21and22each other in a vertical direction to deform to a plane shape and control height h, and enlarging the intersecting portion contacting each other and then connecting the center portions of the first and second crossmembers21and22each other with welding.

In other words, a front area21A and a rear area21B of the first crossmember21, and a front area22A and a rear area21B of the second crossmember22are connected one another by the intersecting portion23to form a crossmember20in the form of an approximate “X” in plan view, and consequently the crossmember20is bridged and connected between the rear side frames1and5.

Subsequently, a structure of the connecting portion of the front end21aof the first crossmember21and the rear side frame1is explained by reference ofFIG. 2illustrating a section view,FIG. 5illustrating a principal perspective view of the connecting portion omitting outer panel3andFIG. 6illustrating an exploded perspective view.

A mounting hole2gfor mounting a structure to be equipped with a suspension is perforated on the lower surface2cof the inner panel2of the rear side frame1connected to the front end of the first crossmember21, and an opening2hin the form of rectangular is formed the inner surface2a. A pipe31mounting and supporting suspension members (mentioned later) and serving as a spacer between the upper surface2band the lower surface2cis extended in a vertical direction and formed so as to be insertable between the upper surface2band the lower surface2cof the rear side frame1.

On the other hand, a connecting portion25of the pipe in the form of semicylinder which can be fitted to a circumference of the pipe31and extends in a vertical direction is connected to the front end21aof the first crossmember21by welding, and the front end21aof the first crossmember21connected to the rear side frame1by an upper bracket26and a lower bracket27.

The upper bracket26has a crossmember connecting portion26ain the form of circular in section view that is fitted to the upper surface of the front end21aof the first crossmember21from the upper side, a frame connecting portion26bextending in the a fore-and-aft direction with overlapping a upper surface2bof the inner panel2from the upper side, and a pair of flanges26cextending from the front and rear ends of the frame connection portion26balong both sides of the crossmember26a, respectively. Further these crossmember connecting portion26a, frame connecting portion26band flanges26care monolithically formed through a connecting portion26d.

The lower bracket27has a crossmember connecting portion27ain the form of circular in section view that is fitted to the lower surface of the front end21aof the first cross member21from the lower side, a connecting portion27bof a lower surface of the frame extending in the a fore-and-aft direction and overlapping a lower surface2cof the inner panel2from the lower side, a pair of connecting portions27cof an inner surface of the frame bended at the front and rear ends of connecting portion27bof a lower surface of the frame to extend and overlap the inner surface2a, and a pair of flanges27dbent at the upper edges of the connecting portion27cof a lower surface of the frame to extend and overlap the flanges26cof the upper bracket26, and these are monolithically formed through a connecting portion27e. The mounting hole27fis perforated on the connecting portion27bof a lower surface of the frame.

The lower bracket27has a crossmember connecting portion27ain the form of circular in section view that is fitted to the lower surface of the front end21aof the first cross member21from the lower side, a connecting portion27bof a lower surface of the frame extending in the a fore-and-aft direction and overlapping a lower surface2cof the inner panel2from the lower side, a pair of connecting portions27cof an inner surface of the frame bended at the front and rear ends of connecting portion27bof a lower surface of the frame to extend and overlap the inner surface2a, and a pair of flanges27dbended at the upper edges of the connecting portion27cof a lower surface of the frame to extend and overlap the flanges26cof the upper bracket26, and these are monolithically formed through a connecting

The above connecting portions are each carried out by first inserting the pipe31between the upper surface2band lower surface2cof the inner panel2of the rear side frame1such that the location of the pipe31is corresponded to that of the mounting hole2gto be subjected to making the positioning, and then welding the pipe31to the upper surface2band lower surface2cof the inner panel2and welding a pipe connecting portion25to the front end of the first crossmember21.

The front end21aof the first crossmember provided with the pipe connecting portion25is inserted into the inner panel2from the opening2hformed on the inner surface2aof the inner panel2to fit the pipe connecting portion25to the pipe31and simultaneously welding the pipe connecting portion25and the pipe31to each other.

Subsequently, the crossmember connecting portion26aand the frame connecting portion26bof the upper bracket26are piled and fitted to the upper surface of the front end21aof the first crossmember21and the upper surface2bof the inner panel2from the upper side, respectively, and the crossmember connecting portion26ais welded to the upper surface of the first crossmember21and simultaneously the frame connecting portion26bis welded to the upper surface2bof the inner panel2. Similarly, the crossmember connecting portion27aof the lower bracket27, the connecting portion27bof a lower surface of the frame, the connecting portion27cof an inner surface of the frame and the flange27dare piled and fitted to the lower surface of the front end21aof the first crossmember21, the lower surface2cand the inner surface2aof the inner panel2and the flange26cof the upper bracket26from the lower side, respectively, and the positioning of the mounting hole27fand the mounting hole2gperforated on the lower surface2cof the inner panel2is made, and then the crossmember connecting portion27ais welded to the lower surface of the first crossmember21, the connecting portion27bof a lower surface of the frame and the connecting portion27cof an inner surface of the frame are welded to the lower surface2cand inner surface2aof the inner panel2, respectively, and simultaneously the flange26cof the upper bracket26and the flange27dof the lower bracket27are welded to each other.

Although detailed explanation is not described, similarly, the rear end21bof the first crossmember21and the front end22aand rear end22bof the second crossmember22are connected to the inner panel2,6of the rear side frames1,5through the upper bracket26and lower bracket27, respectively, and the pipe connecting portions welded to the rear end21b, the front end22aand the rear end22bare welded to the pipe.

Thereafter, the upper edge and lower edge of the outer panel3are welded to the flanges2d,2eof the inner panel to form the rear side frame1in the form of closed cross section (hollow). Similarly, the inner panel6and outer panel7form the rear side frame5in the form of closed cross section (hollow).

A structure for mounting a suspension including a pipe31provided in the rear side frames1and5is explained by reference ofFIG. 2illustrating a section view.

The pipe31, which disposed in the inner panel2of the rear side frame1by connecting to the front end21aof the first crossmember21, has a flange31aformed on its lower end, and a screw portion31cand spacer-fitting portion31dformed on a lower portion of a through hole31band is in the form of tube. The pipe31is welded such that the upper end and lower end are in contact with the upper surface2band lower surface2cof the inner panel2, respectively.

A bushing32is provided with an outer pipe32aand an inner pipe32bto which are connected to various arm members of the suspension, elastic members32cdisposed between these pipes and a pipe-shaped spacer32dto which is connected to the inside of the inner pipe32band of which upper end is capable of fitting to a spacer fitting portion31d. The bushing32is mounted on a lower surface of the rear side frame I by a mounting bolt33screwed to a screw mounting portion31cwhich is inserted in the spacer32dfrom the lower side to pass through a mounting hole27fof the under bracket27and a mounting hole2gof the lower surface2cand is consequently formed in a through hole31bof the pipe31. Similarly, various arm members are supported on the rear end21bof the first crossmember21, the front end22aand the rear end22bof the second crossmember22, and the connecting portion of the rear side frames1,5by the structure for supporting a suspension, whereby rear suspensions for supporting rear wheels are mounted.

By adopting the above-mentioned structure, load and vibration applied to the bushing32from the rear wheels through the suspensions during driving are transmitted to the pipe31from the bushing32through the mounting bolt33to be dispersed from the whole rear side frame1. Simultaneously a part of the load and vibration is transmitted from the pipe31to the front end21aof the first crossmember21and further transmitted from the rear end21bto the other rear side frame5through the first crossmember, while the part is also dispersed from the intersecting portion23to the second crossmember22, from the front end22aof the second crossmember22to the rear side frame5, and from the rear end22bto the rear side frame1, whereby it can be efficiently transmitted and dispersed throughout the rear portion of the body. Similarly, load and vibration applied from the suspensions are transmitted and dispersed to the rear end21bof the first crossmember21, the front end22aand rear end22bof the second crossmember22and the connecting portion of the rear side frames1,5through the rear side frames1,5and the first and second crossmembers21,22, whereby the load and vibration can be efficiently transmitted and dispersed throughout the rear portion of the body to ensure high stiffness for supporting the rear suspensions.

Subsequently, the rear structure of a vehicle body formed in the above manner is explained on its action.

In case impact load and vibration from the suspension members caused by driving bring about deformation in torsion of the body, counterforce (reaction) to the tension or compression caused by the impact load and vibration is generated in the first and second crossmembers21,22obliquely intersected and bridged between the right and left rear side frames1and5. The resultant counterforce depresses the relative deformation of the right and left rear side frames1,5to greatly enhance stiffness of the body such as stiffness in torsion of a whole body. Further, the enhanced stiffness of the rear body can ensure high stiffness of the whole body.

Further, since the pipe31for attaching the suspension members to the rear side frames1,5and supporting them is connected to the rear side frame1and the front end21aof the first crossmember21, impact load and vibration applied from the suspension member to the pipe31during driving are dispersed to the front and back of the body by the rear side frame1provided with the pipe31, and simultaneously dispersed and transmitted from the rear end21bto the other rear side frame5through the first crossmember21, and from the front end22aof the second crossmember22connected crosswise to the first crossmember21to the rear side frame5through the second crossmember22, and further from the rear end22bto the rear side frame1whereby the impact load and vibration are efficiently dispersed and transmitted throughout the rear portion of the body. Similarly, impact load and vibration applied to the pipe31from other suspension members are also sufficiently dispersed to the whole rear portion of the body through the rear side frames1,5, the first crossmember21and the second crossmember22. Hence, impact load and vibration applied to the pipe31from the suspension members during driving are sufficiently dispersed to the whole rear portion of the body by the right and left rear side frames1,5and the first and second crossmembers21,22whereby high stiffness for supporting the suspension is ensured to improve drivability and driving stability of vehicle.

As shown inFIG. 7, in case impact load given from the side of the body, e.g., impact load P1is applied to a whole surface of the rear portion of the body, or an interval between the connecting portion of the rear side frame1and the front end21aof the first crossmember21and the connecting portion of the rear side frame1and the rear end22bof the second crossmember22, the impact load P1is transmitted and dispersed to a wide area of the vehicle body in the fore-and-aft direction of the body through the rear side frame1, and simultaneously a part of the impact load P1is dispersed to the front end21aof the first crossmember21and the rear end22bof the second crossmember22through the rear side frame1to be applied to them.

The impact load applied at the front end21aof the first crossmember is transmitted from the rear end21bof the first crossmember21to the other rear side frame5through the first crossmember21, and a part of the impact load is dispersed from the intersecting portion23to the front area22A of the second crossmember22and further transmitted from the front end22ato the rear side frame5, whereby the impact load is dispersed to a wide area of the rear side frame5. On the other hand, the impact load applied to the rear end22bof the second crossmember22is transmitted from the front end22aof the second crossmember22to the other rear side frame5through the second crossmember22, and a part of the impact load is dispersed from the intersecting portion23to the rear area21B of the first crossmember21and further transmitted from the rear end21bto the rear side frame5, whereby the impact load is dispersed to a wide area of the rear side frame5.

Hence, the impact load P1is dispersed from the right and left rear side frames1,5and the first and second crossmember21,22to the whole rear portion of the body to be efficiently absorbed by the whole rear portion, whereby impact to the passenger can be relaxed to ensure safe of the passenger.

In case impact load P2is applied from the side of the vehicle body to the vicinity of the connecting portion of the rear side frame1and the front end21aof the first crossmember11, the impact load P2is transmitted and dispersed to a wide area of the vehicle body in the fore-and-aft direction of the body through the rear side frame1, and mainly dispersed and transmitted from the rear side frame1to the front end21aof the first crossmember21.

In this case, the impact load applied to the front end21aof the first crossmember21is transmitted from the rear end21bof the crossmember21to the other rear side frame5through the first crossmember21, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the front area22A of the second crossmember22and further transmitted from the front end22ato the rear side frame5. Further, the part is dispersed to the rear area22B of the second crossmember22and further transmitted from the rear end22bto the rear side frame1.

Hence, the impact load P2is dispersed from the right and left rear side frames1,5and the first and second crossmembers21,22to the whole rear portion of the body to be efficiently absorbed by the whole rear portion.

Further, in case impact load P3is applied from the side of the vehicle body to the vicinity of the connecting portion of the rear side frame1and the rear end22bof the second crossmember22, the impact load P3is transmitted and dispersed to a wide area of the vehicle body in the fore-and-aft direction of the body through the rear side frame1, and mainly dispersed and transmitted from the rear side frame1to the rear end22bof the second crossmember22.

In this case, the impact load applied to the rear end22bof the second crossmember22is transmitted from the front end22aof the second crossmember22to the other rear side frame5through the second crossmember22, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the rear area21B of the first crossmember21and further transmitted from the rear end21bof the rear area21B to the rear side frame5, whereby the part is dispersed and transmitted to the wide area of the rear side frame5. Further, the part is dispersed to the front area21A of the first crossmember21and further transmitted from the front end21ato the rear side frame1.

Hence, the impact load P3is dispersed from the right and left rear side frames1,5and the first and second crossmembers21,22to the whole rear portion of the body to be efficiently absorbed by the whole rear portion.

In case a relatively little impact load P4is applied to a central portion of the body in the width direction or the whole body from the back side, the impact load P4is dispersed and transmitted to the right and left rear side frame1,5and the rear ends1a,5athrough the rear skirt19, the bumper beam etc. Since the impact load is efficiently dispersed to the right and left rear side frames1,5, this dispersion (transmission) of the impact load to the right and left rear side frames1,5prevents generation of the phenomenon (referred to as frame opening) in which the rear ends1a,5aof the right and left rear side frames1,5are part from each other due to the connection of the rear ends1a,5aand the rear skirt19, the bumper beam etc.

The impact load applied to the rear end1a of the rear side frame1is dispersed and transmitted from the rear side frame1to the side sill to which the front area of the rear side frame1is connected and the rear end22bof the second crossmember22. The impact load applied to the rear end22bis transmitted from the front end22aof the second crossmember22to the rear side frame5through the second crossmember22, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the rear area21B of the first crossmember and then dispersed from the rear end21bof the rear area21B to the rear side frame5, whereby the impact load is dispersed and transmitted to the wide area of the rear side frame5. The part of the impact load is also dispersed from the intersecting portion23to the front area21A of the first crossmember21, and then dispersed from the front end22a21aof the front area21A to the rear side frame1.

On the other hand, the impact load applied to the rear end5aof the rear side frame5is dispersed and transmitted from the rear side frame5to the side sill to which the front area of the rear side frame5is connected and the rear end21bof the first crossmember21. The impact load transmitted to the rear end21bis transmitted from the front end21aof the first crossmember21to the rear side frame1through the first crossmember21, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the rear area22B of the second crossmember22and then dispersed from the rear end22bof the rear area22B to the rear side frame1, whereby the impact load is dispersed to the wide area of the rear side frame1. The part of the impact load is also dispersed from the intersecting portion23to the front area22A of the second crossmember22, and then dispersed from the front end22aof the front area22A to the rear side frame5.

Hence, the impact load P4is dispersed to the whole body through the right and left rear side frames1,5and the first and second crossmembers21,22to be efficiently absorbed by the whole body.

In case an excess impact load P4is applied to a central portion of the body in the width direction or the whole body, the impact load P4is dispersed and transmitted to the right and left rear side frames1,5and the rear ends1a,5athrough the rear skirt19, the bumper beam etc. This impact load applied dispersedly to the right and left rear side frames1,5is efficiently dispersed and transmitted to the rear side frames1,5and then dispersed to the whole body through the rear side frames1,5, the first crossmember21, the second crossmember22, etc. because the rear ends1a,5aof the right and left rear side frames1,5are connected to each other by the rear skirt19, the bumper beam etc. whereby generation of the frame opening is prevented.

In this case, the impact load remains partially without being dispersed and transmitted to the whole body. The remaining impact load causes collapsing deformation of the rear side frame1to be absorbed. In this case, the area of the rear side frame1in which the approximately X-shaped crossmember20is provided is set such that stiffness (i.e., counter force) against load in the fore-and-aft direction is ensured by the first and second crossmembers21and22while stiffness in the rear area protruded more rearwardly than this crossmember20is relatively low. Therefore, the impact load applied to the rear end1aof the rear side frame1depresses the rear area of the rear side frame1whereby the impact load is absorbed. Similarly, the area of the rear side frame5in which the approximately Xshaped crossmember20is provided is set such that stiffness, to load in the fore-and-aft direction is ensured by the first and second crossmembers21and22while stiffness in the rear area protruded more rearwardly than this crossmember20is relatively low, and therefore, the impact load applied to the rear end5aof the rear side frame5depresses the rear area of the rear side frame5whereby the impact load is absorbed.

Hence, when an excess impact load P4is applied to a central portion of the body in the width direction or the whole body from the back side, the rear areas of the rear side frames1and5are effectively utilized as crash stroke, i.e., the impact load is efficiently absorbed by smooth collapsing deformation of the rear side frames1,5whereby relaxation of the impact loads is brought about to ensure safety of crews of vehicle.

Further, in case a relative little impact load is offset in one side of width direction of the body, for example impact load P5offset in the side of the rear side frame1, is applied from the back side, the impact load P5is mainly applied to the rear end1aof the rear side frame1and simultaneously a part of the impact load P5is dispersed and transmitted to the rear end5aof the rear side frame5through the rear skirt19, bumper beam, etc.

The impact load applied to the rear end1aof the rear side frame1is dispersed and transmitted from the rear side frame1to the side sill to which the front portion of the rear side frame1is connected and the rear end22bof the second crossmember22. The impact load transmitted to the rear end22bof the second crossmember22is transmitted from the front end22aof the second crossmember22to the rear side frame5through the second crossmember22, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the rear area21B of the first crossmember, and also transmitted from the rear end21bto the rear side frame5whereby the impact load is transmitted to the wide area of the rear side frame5. Also, the part is dispersed from the intersecting portion23to the front area21A of the first crossmember21and then dispersed from the front end21ato the rear side frame1.

On the other hand, the impact load applied to the rear end5aof the rear side frame5is dispersed and transmitted from the rear side frame5to the side sill to which the front portion of the rear side frame5is connected and the rear end21bof the first crossmember21. The impact load transmitted to the rear end21bof the first crossmember21is transmitted from the front end21aof the first crossmember21to the rear side frame1through the first crossmember21, and simultaneously a part of the impact load is dispersed from the intersecting portion23to the rear area22B of the second crossmember22, and also transmitted from the rear end22bto the rear side frame1whereby the impact load is transmitted to the wide area of the rear side frame1. Also, the part is dispersed from the intersecting portion23to the front area22A of the second crossmember22and then dispersed from the front end22ato the rear side frame5. Hence, the impact load P5is efficiently dispersed to the whole body through the right and left rear side frames1,5and the first and second crossmembers21,22to be absorbed by the whole body.

Further, in case impact load P5offset and applied to the side of the rear side frame1from the back side is excess, the impact load P5is mainly applied to the rear end1aof the rear side frame1and simultaneously a part of the impact load P5is dispersed and transmitted to the rear end5aof the rear side frame5through the rear skirt19, bumper beam, etc. The impact load applied to the rear end1aof the rear side frame1is dispersed and transmitted from the rear side frame1to the side sill to which the front portion of the rear side frame1is connected and the rear end22bof the second crossmember22, and then dispersed and transmitted to the rear side frames1and5with the rear ends1a,5aof the right and left rear side frames1,5being connected to each other by the rear skirt19, the bumper beam etc. to prevent generation of the frame opening, whereby the impact load is dispersed to the whole body through the right and left rear side frames1,5, the first and second crossmembers21,22.

The impact load applied to the rear side frame1remains partially without being dispersed and transmitted to the whole body. The remaining impact load causes collapsing deformation of the rear side frame1to be absorbed. In this case, the area of the rear side frame1in which the approximately X-shaped crossmember20is provided is set such that stiffness against load in the fore-and-aft direction is ensured by the first and second crossmembers21and22while stiffness in the rear area is relatively low. Therefore, the impact load applied to the rear end1aof the rear side frame1depresses the rear area of the rear side frame1whereby the impact load is absorbed.

Hence, when an excess impact load P5is offset and applied to the side of the rear side frame1, the impact load P5is mainly absorbed by smooth collapsing deformation of the rear area of the rear side frame1, and simultaneously the impact load P5is also dispersed and transmitted to the other rear side frame5through the rear skirt9, bumper beam, etc. to be absorbed by collapsing deformation of the rear area of the rear side frame5, whereby relaxation of the impact loads is brought about to ensure safety of crews of vehicle.

Similarly, the area of the rear side frame5in which the approximately X-shaped crossmember20is provided is set such that stiffness against load in the fore-and-aft direction is ensured by the first and second crossmembers21and22while stiffness in the rear area at the rearward of the crossmember20is relatively low. Therefore, the impact load applied to the rear end5aof the rear side frame5depresses the rear area of the rear side frame5whereby the impact load is absorbed.

Hence, when an excess impact load P5is offset and applied to the side of the rear side frame1or5from the back side, the rear areas of the rear side frames1and5are effectively utilized as crash stroke, i.e., the impact load is efficiently absorbed by smooth collapsing deformation of the rear side frames1,5, whereby relaxation of the impact loads is brought about to ensure safety of crews of vehicle.

According to the rear structure of vehicle body of the embodiment, thus, by disposing the approximately X-shaped crossmember20is between the right and left rear side frames1,5, relative deformation between the right and left rear side frames1,5due to impact load or vibration brought out from suspension during driving is suppressed to ensure high stiffness of the whole body. Further stiffness for supporting the suspension can be also obtained to ensure drivability and driving stability. Also, in case impact load is applied to the body from its side or its back side, the impact load is efficiently dispersed and transmitted to the whole body to relax the impact against the crews ensuring safety of the crews.

Further, a simple structure of the crossmember20approximately in the form of “X” in plan view that is obtained by the first and second crossmembers21and22being bridged crosswise between the right and left rear side frames1,5ensures high stiffness of the body without increase of the body weight. Moreover, the crossmember20obtained by disposing crosswise the first and second crossmembers21and22is compact, and therefore the crossmember20occupies a little space to facilitate arrangement of a fuel tank or a part for mounting a spare tire, whereby freedom of body design can be ensured. Furthermore, the pipe31for mounting and supporting the suspension members are connected to the crossmember20in the rear side frames1,5, and hence this connecting portion can be arranged and compactly mounted within the rear side frames1,5. Thus, the space occupied by the connecting portion can be reduced to ensure freedom of body design.

In the explanation above, the intersecting portion in which the first crossmember21and the second crossmember22are connected each other is formed by deforming the center portions, in which the first crossmember21and the second crossmember22are intersected each other, so as to be on one plane and welding the center portions. However, the crossmember20can be also formed as shown inFIG. 8illustrating a perspective view, i.e., the first crossmember21is cut to the front area21A and the rear area21B and the second crossmember22is cut to the front area22A and the rear area22B, and then the rear end21cof the front area21A and the front end21dof the rear area21B of the first crossmember21, and the rear end22cof the front area22A and the front end22dof the rear area22B of the second crossmember22are fitted to inserting holes28a,28b,28c,28dof a cast-metal joint28, respectively to be welded, whereby the approximately X-shaped crossmember20monolithically connected one another is formed.

Further, the crossmember20can be also formed as shown inFIG. 9illustrating a perspective view, i.e., the first crossmember21is cut to the front area21A and the rear area21B and the second crossmember22is also cut to the front area22A and the rear area22B, and simultaneously a screw portion is formed on the rear end21cof the front area21A and the front end21dof the rear area21B of the first crossmember21, and the rear end22cof the front area22A and the front end22dof the rear area22B of the second crossmember22, and then the screw portions of the rear end21cof the front area21A and the front end21dof the rear area21B of the first crossmember21, and the rear end22cof the front area22A and the front end22dof the rear area22B of the second crossmember22are screwed into screw holes29a,29b,29c,29dof a cast-metal joint29, respectively to be welded, whereby the approximately X-shaped crossmember20monolithically connected one another is formed.

According to these structures, the front area21A and rear area21B of the first crossmember21, and the front area22A and rear area22B of the second crossmember22are connected to each other through the cast-metal joint28or29whereby the intersecting portion23of the first crossmember21and the second crossmember22is improved in its connecting stiffness to provide the crossmember20improved in stiffness.

In the explanation above, the front end21aand the rear end21bof the first crossmember21, and the front end22aand rear end22bof the second crossmember22are connected to the right and left rear side frames1,5. However, the following structure can be adopted; i.e., the front end21aof the first crossmember21is extended to the lower end of C-pillar13, similarly, the rear end21bto the lower end of the D-pillar16, the front end22aof the second crossmember22to the lower end of the C-pillar14, and the rear end22bto the lower end of the D-pillar15, respectively, whereby connecting stiffness between the front end21aof the first crossmember21and C-pillar13, that between the rear end21band D-pillar16, that between the front end22aof the crossmember22and C-pillar14and that between the rear end22band D-pillar15are enhanced to further improve the stiffness of the rear portion of the body, and simultaneously it is also possible that the impact load applied from the side or the back side of the body is transmitted to the side and the upper side of the body through C-pillar13,14and D-pillar15,16to be efficiently dispersed to the whole body.

Second Embodiment

The second embodiment is explained by reference ofFIG. 10to FIG.13. InFIG. 10toFIG. 13, parts corresponding toFIG. 1toFIG. 9are given the same reference numbers as inFIG. 1toFIG. 9to omit the detailed description of the parts.

FIG. 10is a schematically perspective view showing the rear structure of vehicle body. The first crossmember41is bridged between the right and left rear side frames1and5. The front end41aof first crossmember41is connected to the rear side frame1in the vicinity of a portion S for mounting a rear suspension, and simultaneously the rear, end41bof first crossmember41is connected to the other rear side frame5in the vicinity of a portion S for mounting suspension, the first crossmember41linearly shifting to the rear side of the body with moving form the rear side frame1to the other rear side frame5. On the other hand, the second crossmember42is bridged between the right and left rear side frames1and5. The front end42aof the second crossmember42is connected to the rear side frame5corresponding to a portion S for mounting a rear suspension, and simultaneously the rear end42bof second crossmember42is connected to the other rear side frame1corresponding to a portion S for mounting a rear suspension, the second crossmember42linearly shifting to the rear side of the body with moving form the rear side frame5to the rear side frame1and intersecting to the first crossmember41at its central portion.

These first and second crossmembers41and42are in the form of pipe having section view of rectangular which are formed by hydroforming. In the intersecting portion43of the crossmembers, the first and second crossmembers41and42are connected each other to form the crossmember40in the form of approximate “X” in plan view.

The intersecting portion43, as shown inFIG. 11illustrating a principal and exploded perspective view of the crossmember, is formed as follows: A concave part in the form of approx. rectangular is formed on the upper central portion of the first crossmember41to provide a fitting concave part41c, a concave part in the form of approx. rectangular is formed on the lower central portion of the second crossmember42to provide a fitting concave part42c, and the fitting concaves41cand42care fitted in and welded each other to connect the first crossmember41and the second crossmember42, which results in formation of the crossmember40in the form of approximate “X” in plan view.

The connecting portion of the front end41aof the first crossmember and the rear side frame1is performed, as shown inFIG. 11illustrating a exploded perspective view of the crossmember, as follows: Fitting parts41din which the inner panel2of the rear side frame1is fitted are formed on the front surface and rear surface of the front end41aof the first crossmember41, and the flanges41e,41fformed on the upper surface and lower surface of the front end41aare welded to the upper surface2band lower surface2cof the inner panel2to connect the front end41aof the first crossmember41to the rear side frame1. Similarly, the rear end41bof the first crossmember41, the front end42aand rear end42bof the second crossmember42and the rear side frames1,5are also connected one another in the same manner as above.

According to the present embodiment described above, in addition to the constitutions of the first embodiment, the first and second crossmembers41,42are formed by hydroforming having wide freedom of design of the shape and excellent processing characteristics, and the fitting concave part41cformed on the upper central portion of the first crossmember41and the fitting concave part42cformed on the central portion of the second crossmember42are fitted in and connected to each other whereby the connecting stiffness between the intersecting portion43of the first crossmember41and the second crossmember42is easily ensured to bring about the improved stiffness of the crossmember40. Further, the front ends41a,42aand the rear ends41b,42bof the first crossmember41and the second crossmember42are fitted in the rear side frame1or5and connected to each other by a flange formed by themselves, and therefore the rear side frames1,5and the crossmember40are directly connected to each other without a bracket to bring about simplification of the constitution and easily bring about high stiffness of the connecting portion.

As shown inFIG. 13illustrating a principal exploded view of the intersecting portion43, it is also possible that the width of the central portion of the first crossmember41where the fitting concave part41cis formed and the width of the central portion of the second crossmember42where the fitting concave part42cis formed are enlarged to enhance connecting stiffness of the intersecting portion43.

Similarly to the first embodiment, the front end41aof the first crossmember41is extended to the lower end of C-pillar13, the rear end41bto the lower end of the D-pillar16, the front end42aof the second crossmember42to the lower end of the C-pillar14, and the rear end42bto the lower end of the D-pillar15, respectively, whereby connecting stiffness between the front end41aof the first crossmember41and C-pillar14and that between the rear end41band D-pillar16, and that between the front end42aof the second crossmember42and C-pillar14and that between the rear end42band D-pillar15are enhanced to further improve stiffness of the rear portion of the body and simultaneously it is also possible that the impact load applied from the side or the back side of the body is transmitted to the sides and the upper side of the body through C-pillars13,14and D-pillars15,16to be efficiently dispersed to the whole body.

Third Embodiment

The third embodiment is explained by reference of FIG.14and FIG.15. This embodiment is characterized in that the crossmember50made of sheet metal is used instead of the crossmember20of the first embodiment or the crossmember40of the second embodiment, and therefore the other constitutions are the same as in the first embodiment or the second embodiment. Thus the crossmember50is mainly explained.

FIG. 14shows an exploded perspective view of the crossmember50, andFIG. 15shows a perspective view of the assembled crossmember50.

The crossmember50is made up of a front crossmember53monolithically formed from a front area51A of a first crossmember51and a front area52A of a second crossmember52, a rear crossmember57monolithically formed from a rear area51B of a first crossmember51and a rear area52B of a second crossmember52, and a connecting member61for connecting the front crossmember53and the rear crossmember57.

The front crossmember53is composed of a bottom surface54, a front surface55and a rear surface56and is in the form of “U” in section view, the front crossmember53extending approximately in the width direction of the body to be opened upward. Flanges55a,56a, which connect to a under surface of the floor panel, are formed on the upper edges of the front surface55by bending and the rear surface56, a flange54b, which connects to a under surface2cof the rear side frame1in the vicinity of the portion for mounting a suspension, is formed on one end of the bottom surface54, and flanges55b,56b, which connect to the inner surface2aof the rear side frame1, are formed on one end of the front surface55and one end of the rear surface56by bending. Similarly, a flange54c, which connects to a under surface6cof the rear side frame5in the vicinity of the portion for mounting a suspension, is formed on the other end of the bottom surface54, and flanges55c,56c, which connect to the inner surface6aof the rear side frame1, are formed on the other ends of the front surface55and the rear surface56by bending. This front crossmember53has a central portion53A positioned on a central portion in the width direction of the body and extending in the width direction, a linear front area51A shifting to the front side of the body with moving from the central portion53A to the rear side frame1, and a linear front area52A shifting to the front side of the body with moving from the central portion53A to the rear side frame5.

On the other hand, the rear crossmember57is composed of a bottom surface58, a front surface59and a rear surface60and is in the form of “U” in section view, the rear crossmember57extending approximately in the width direction of the body to be opened upward. Flanges59a,60a, which connect to a under surface of the floor panel, are formed on the upper edges of the front surface59and the rear surface60by bending, a flange58b, which connects to an under surface2cof the rear side frame1in the vicinity of the portion for mounting a suspension, is formed on one end of the bottom surface58, and flanges59b,60b, which connect to the inner surface2aof the rear side frame1, are formed on one end of the front surface59and one end of the rear surface60by bending. Similarly, a flange58c, which connects to a under surface6cof the rear side frame5in the vicinity of the portion for mounting a suspension, is formed on the other end of the bottom surface58, and flanges59c,60c, which connect to the inner surface6aof the rear side frame5, are bent and formed on the other end of the front surface59and the other end of the rear surface60by bending. This rear crossmember57has a central portion57A positioned on a central portion of the body in the width direction and extending in the width direction, a linear rear area52B shifting to the rear side of the body with moving from the central portion57A to the rear side frame1, and a linear rear area51B shifting to the rear side of the body with moving from the central portion57A to the rear side frame5.

The connecting member61is composed of a base portion62bridged between the bottom surface54of the central portion53A of the front crossmember53and the bottom surface58of the central portion57A of the rear crossmember57, a flange63formed on the front end of the base portion by bending and connected to the rear surface56of the front crossmember53, and a flange64formed on the rear end of the base portion by bending and connected to the front surface59of the rear crossmember57.

The front crossmember53and the rear crossmember57are monolithically combined with each other, as shown inFIG. 15illustrating the perspective view, by putting the base portion62of the connecting member61on both of the bottom surface54of the front crossmember53and the bottom surface58of the rear crossmember57and welding them, and simultaneously welding the flange63,64to the corresponding portions of the rear surface56of the front crossmember53and the front surface59of the rear crossmember57. By this connection (bonding), the front area51A of the front crossmember53and the rear area51B of the rear crossmember57extend continuously and linearly to form an approximate linear first crossmember51, and simultaneously the front area52A of the front crossmember53and the rear area51B of the rear crossmember57extend continuously and linearly to form an approximate linear second crossmember52, whereby a crossmember50in the form of approximate “X” in plan view, in which the first crossmember51and the second crossmember52are intersected each other, can be formed.

In the resultant crossmember, the flanges55a,56aof the front crossmember53and the flanges59a,60aof the rear crossmember57are welded to the floor panel between the right and left crossmembers1and5to form a hollow having closed cross section which consists of the front crossmember53and the floor panel and which continuously extends along the central portion53A and the front areas51A and52A of the crossmember53and to simultaneously form a hollow having closed cross section which continuously extends along the central portion57A and the rear areas51B and52B.

Further, the flange54bformed on one end of the bottom surface54of the front crossmember53is welded to the lower surface2cof the rear side frame1, and the flanges55b,56bformed on one ends of the bottom surfaces55and56are welded to the inner surface2aof the rear side frame1, whereby the front end51aof the front area51A of the front crossmember53is connected to the rear side frame1in the vicinity of a structure (portion) for mounting a suspension. Similarly, the flanges54c,55c,56care welded to the lower surfaces6cand inner surface6aof the other rear side frame5, whereby the front end52aof the front area52A of the front crossmember53is connected to the rear side frame5in the vicinity of a structure (portion) for mounting a suspension.

Further, the flange58bformed on one end of the bottom surface58of the rear crossmember57is welded to the lower surface2cof the rear side frame1, and the flanges59b,60bare welded to the inner surface2aof the rear side frame1, whereby the rear end52aof the rear area52B of the rear crossmember57is connected to the rear side frame1in the vicinity of a structure (portion) for mounting a suspension. Similarly, the flanges58c,59c,60cformed on one end of the bottom surface58, front surface59and rear surface60of the other rear crossmember57respectively are welded to the lower surfaces6cand inner surface6aof the other rear side frame5, whereby the rear end51bof the rear area51B of the rear crossmember57is connected to the rear side frame5in the vicinity of a structure (portion) for mounting a suspension.

In the rear structure of the vehicle body described above, similarly to the first embodiment, the crossmember50in the form of “X” in plan view obtained by obliquely intersecting and connecting the first crossmember51to the second crossmember52is bridged between the right and left rear side frames1,5, the first crossmember51in the form of straight line being formed from the front area51A of the front crossmember53and the rear area51B of the rear crossmember57, and the second crossmember52in the form of straight line being formed from the front area52A of the front crossmember53and the rear area52B of the rear crossmember57. Hence, in case impact load and vibration applied from the suspension members during driving cause deformation in torsion of the body, counter-force (reaction) to the tension or compression by the impact load and vibration generated in the first and second crossmembers21,22depresse the relative deformation of the right and left rear side frames1,5to greatly enhance stiffness of the body such as stiffness in torsion of the rear body. Further, the enhanced stiffness of the rear body can ensure high stiffness of the whole body, and high stiffness for supporting a suspension is also obtained to ensure drivability and driving stability. Further, in case impact load is applied from the side or the rear side, the impact load is efficiently dispersed and transmitted to the whole body to relax the impact against the crews ensuring safety of the crews.

In addition to the first embodiment, the third embodiment uses relative thin sheet metal for forming the crossmember50, whereby the weight of the vehicle body is reduced and the crossmember50can be prepared by a pressing having excellent productivity to bring about reduction of production cost.

Further, the front end51aof the first crossmember51is extended to the lower end of C-pillar13, similarly, the rear end51bto the lower end of the D-pillar16, the front end52aof the second crossmember52to the lower end of the C-pillar14, and the rear end52bto the lower end of the D-pillar15, respectively, whereby connecting stiffness between the front end51aof the first crossmember51and C-pillar13, that between the rear end52band D-pillar16, that between the front end52aof the second crossmember52and C-pillar14and that between the rear end51band D-pillar15, are enhanced to further improve the stiffness of the rear portion of the body and simultaneously it is also possible that the impact load applied from the side or the back side of the body is transmitted to the side and the upper side of the body through C-pillars13,14and D-pillars15,16to be efficiently dispersed to the whole body.

EFFECT OF THE INVENTION

According to the rear structure of the vehicle body of the invention, the crossmember in the form of approximate “X” in plan view formed by obliquely intersecting a first crossmember and a second crossmember is disposed between the right and left rear side frames, while at least one of the front ends of the first and second crossmembers and the rear ends of the first and second crossmembers is connected to the rear side frames in vicinity of a structure to be equipped with a suspension, or directly connected to the structure. Therefore, the first and second crossmembers suppress relative deformation of the right and left rear side frames to give high stiffness of the rear portion of the body and to enhance stiffness for supporting a suspension. Further, if impact load is applied to the body from its side or its rear, the impact load can be dispersed efficiently from the one of the rear side frames to the other of the frames through the X-shaped crossmembers, whereby the impact load can be dispersed to the whole body. Further, the simple structure obtained by intersecting the first and second crossmembers to bridge between the right and left rear side frames brings about improvement of the body stiffness and stiffness for supporting a suspension and reduction of body weight.

The disclosure of Japanese Patent Application No. 2002-320084, dated Nov. 1, 2002, including the specification, drawings and abstract, is hereby incorporated by reference in its entirety.

While the presently preferred embodiments of the present invention have been shown and described, it is to be understood that disclosures are for the purpose of illustration and that various changes and modification may be made without departing from the scope of the invention as set forth in the appended claims.