Vehicle front body structure

Front upper members and front side members located laterally inward of the front upper members are joined with connecting members of pipe form. A first end portion of each connecting member extends through the front side member and is welded to both sides of the side member. The joint has high rigidity. When impact energy acts on either front upper member, the energy is transmitted to the front side member via the connecting member, and the front side member and the front upper member plastically deform.

FIELD OF THE INVENTION

The present invention relates to an improvement in a vehicle front body structure. A “front body part” herein means a portion forward of front pillars and a dashboard.

BACKGROUND OF THE INVENTION

A vehicle front body structure designed to allow a front body part to absorb collision energy in a vehicle frontal crash is disclosed, for example, in Japanese Patent No. 2516212. The vehicle front body structure will be described with reference toFIGS. 12 and 13.

A conventional vehicle body200has a pair of right and left front side members201,201extending longitudinally of the body on the right and left sides of its front part. Right and left front upper members202,202(only the right one shown) extend longitudinally of the body, laterally outside of and above the front side members201,201. Right and left wheel houses203,203are provided between the right and left front side members201,201and the right and left front upper members202,202, respectively.

In front of the right wheel house203, the right front side member201and the right front upper member202are connected at their front portions with front and rear connecting members204,205. The left side of the vehicle body200has the same configuration.

Reference numeral206denotes a front fender. A panel207is extended over the front and rear connecting members204,205. A subframe member208is extended between the right and left front side members201,201. Reference numeral209denotes a front wheel.

When an impact energy En acts from the vehicle front at a position laterally outside of either front side member201in the front part of the body200, or at what is called an offset collision at the front of the body200, the impact energy En acts on the front upper member202, and also acts on the front side member201through the connecting members204,205. The front side member201and the front upper member202plastically deform, thereby mitigating the impact energy En acting toward the passenger compartment. That is, the impact energy En acting on the front upper member202is absorbed not only by the front upper member202but also by the front side member201to some extent.

In order to efficiently absorb such an impact energy En by the front part of the body200, it is conceivable to allow more impact energy En to be transmitted to the front side member201. For this, it is required to increase the rigidity of the connecting members204,205and the rigidity of joined portions of the connecting members204,205.

In the conventional structure, the connecting members204,205are butt-joined at their respective opposite ends to a laterally outer surface201aof the front side member201and a laterally inner surface202aof the front upper member202. With this structure, it is relatively easy to increase the rigidity of the connecting members204,205. However, with this structure as it is, there is a limit to increase the rigidity of the joined portions.

It is thus desired to be able to efficiently absorb an impact energy at an offset impact on the front of a vehicle body, by a front body part with a simple configuration.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a vehicle front body structure which comprises: right and left front side members extending longitudinally of a vehicle body on the right and left sides of a front body part; right and left front upper members provided laterally outside and above the front side members and extending longitudinally of the vehicle body; right and left wheel houses disposed between the right and left front side members and the right and left front upper members, respectively; and right and left connecting members disposed in such a manner as to extend transversely in front of the right and left wheel houses, the right connecting member having a first end portion and a second end portion, the first end portion extending transversely through the right front side member and being weld connected both sides of the right front side member, the second end portion being joined to the right front upper member, the left connecting member having a first end portion and a second end portion, the first end portion of the left connecting member extending transversely through the left front side member and being weld connected to both sides of the left front side member, the second end portion of the left connecting member being joined to the left front upper member.

Thus, in this invention, since the first end portions of the right and left connecting members are transversely extended through the front side members in front of the right and left wheel houses, respectively, each of which being welded to the both sides of the front side member it extends through, the rigidity of joints at which the first end portions of the connecting members are joined to the front side members (that is, base portions of the connecting members) is sufficiently increased by the simple configuration.

As a result, when impact energy acts on either front upper member from the front of the body, the impact energy is transmitted from the front upper member to the front side member via the connecting member and the joint (the base portion of the connecting member) of high rigidity. The front side member and the front upper member then plastically deform, thereby sufficiently mitigating the impact energy acting toward the passenger compartment. That is, the impact energy acting on the front upper member is absorbed not only by the front upper member but also by the front side member sufficiently.

As described above, in this invention, the simple configuration allows impact energy at an offset impact on the front of the body to be dispersed into the front side member and the front upper member, so that the impact energy is efficiently absorbed by the front body part. As a result, the impact energy acting toward the passenger compartment is further mitigated.

Since front portions of the front side members and front portions of the front upper members are connected by the connecting members, the rigidity of the front body part is increased, and the rigidity of the body as a whole including a passenger compartment part is increased.

Further, since the first end portion of each connecting member is attached to the front side member in a transversely penetrating manner, the mounting position of the connecting member relative to the front side member is more easily improved in accuracy.

Preferably, the right and left front side members each comprises a hollow member having an inner side member half toward a vehicle width center line and an outer side member half laterally outside, the inner and outer side member halves having a through-hole formed to allow the first end portion of the connecting member to extend therethrough, and the first end portions of the right and left connecting members are each joined to a joining flange placed against and joined to the outer side member half from laterally outside. Thus, the welding operation for the joints between the connecting members and the front side members can be performed in stages at different times to prevent welding heat distortion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicle10shown inFIG. 1has a body20(i.e., a body frame20) partitioned into a front engine compartment22and a rear passenger compartment23by a dashboard21, and has right and left front pillars24,24put upright near the dashboard21.

A front structure of the body20having a monocoque structure will be described below. A “front part of the body20” herein means a portion forward of the dashboard21and the front pillars24,24in the body20. The dashboard21is a partition board and is also called a dash panel. The front pillars24,24are column supports disposed between a windshield and side glasses.

The front part of the body20has the structure in which a pair of right and left front side members31,31are extended longitudinally on the right and left sides of the front body part; right and left upper members32,32are extended forward from the right and left front pillars24,24, laterally outside of and above the front side members31,31; right and left drooped portions33,33are extended from the front ends of the upper members32,32below the right and left front side members31,31; a front bulkhead40is joined to front portions of the right and left front side members31,31and front portions of the right and left drooped portions33,33; and right and left front damper housings34,34and right and left wheel houses35,35are individually extended between the front side members31,31and the upper members32,32.

Each upper member32and the corresponding drooped portion33are combined into one piece, constituting a front upper member38.

As is clear from the above description, the body20has the right and left front upper members38,38extended longitudinally, laterally outside of and above the right and left front side members31,31, and the right and left front damper housings34,34and the right and left wheel houses35,35individually extended between the right and left front side members31,31and the right and left front upper members38,38.

Right and left front wheels51(Only the left one shown in the figure.) are disposed laterally outside of the front side members31,31.

The rear ends of the front side members31,31are connected to right and left center side members36,36. Each front damper housing34supports an upper portion of a front suspension (not shown) for the front wheel51. Each wheel house35is a cover bulging toward the vehicle center line, covering an upper portion of the front wheel51, and is joined to the front damper housing34.

The front bulkhead40includes a front upper crossmember41extended between upper portions of the right and left drooped portions33,33, a front lower crossmember42extended between lower portions of the right and left drooped portions33,33, and right and left side stays43,43extended between the front upper and lower crossmembers41,42.

The front upper crossmember41is located above the right and left front side members31,31, supporting a radiator (not shown). The front lower crossmember42is located below the right and left front side members31,31, bearing the radiator (not shown). The upright right and left side stays43,43can also be joined to the right and left front side members31,31, increasing the rigidity of the body20.

The body20also has a front bumper beam52extended between front ends31a,31aof the right and left front side members31,31. In the figure, reference numeral27denotes a roof, and37a side sill.

FIG. 2shows the front body part when viewed from the side. The center side member36has an extension39extending forward and upward from its front end. To the front end of the extension39, the rear end of the front side member31is joined. The front pillar24includes a lower pillar portion25as the lower half and an upper pillar portion26as the upper half.

The upper member32is located above the front wheel51, extending from the upper end of the lower pillar portion25, with a forward and downward inclination. The drooped portion33extends from the front end of the upper member32in a downward curve, drooping in front of the front wheel51, and further extends downward nearly vertically.

As shown inFIG. 3, the front lower crossmember42is arranged rearward of the front ends31a,31aof the right and left front side members31,31. The front upper crossmember41is arranged rearward of the front lower crossmember42.

The front upper crossmember41and the front lower crossmember42are transversely elongated round pipes of substantially linear shapes in a plan view.

Longitudinal ends41a,41aof the front upper crossmember41are joined by welding or the like to inside surfaces33b,33bof the right and left drooped portions33,33via right and left joining members44,44. The joining members44,44are gusset plates of a substantially triangular shape in a plan view.

FIG. 4shows the front of the front body part. The front upper crossmember41has a hat-like shape in a front view. The front lower crossmember42has a substantially linear shape also in a front view. Longitudinal ends42a,42aof the front lower crossmember42are joined by bolting, welding or the like to front ends33a,33aof the right and left drooped portions33,33via vertical plate-shaped joining members45,45(seeFIG. 2).

Here, also referring toFIGS. 1 to 3, description will be made. Right and left connecting members60,60connecting the front side members31,31and the drooped portions33,33of the front upper members38,38are arranged forward of the right and left wheel houses35,35and rearward of the front upper crossmember41, extending nearly horizontally from the right and left front side members31,31laterally outward. The connecting members60,60are circular-section round pipes.

The connecting structures of the connecting members60,60will be described in detail below with reference toFIGS. 5 to 7andFIGS. 8A to 8C. The right and left connecting members60,60and the connecting structures are symmetrical with respect to the vehicle width center line CL, and therefore only the left side structure will be shown and the right side structure will not be described.

As shown inFIGS. 5 to 7, the left connecting member60is a round pipe bent in its longitudinal direction. Here, the “round pipe” indicates a generally circular cross section, and may have a perfectly circular cross section or an elliptical cross section. Specifically, as shown inFIG. 6, the connecting member60, when viewed from the top, has a first end portion61extending linearly in a transverse direction and a second end portion62bent forward in a curve at angle θ with respect to the first end portion61.

In the connecting structure of the left connecting member60, (1) the first end portion61of the connecting member60transversely extends through the left front side member31, and is welded to both sides of the front side member31through which it extends, that is, to an inner side member half70and an outer side member half80, and (2) the second end portion62of the connecting member60is joined to the left front upper member38.

As shown inFIG. 7, the front side member31is a hollow member consisting of the inner side member half70toward the vehicle width center line CL and the outer side member half80laterally outside.

The inner side member half70is a sheet-steel press-molded part of a substantially inverted L shape in a front view, a member integrally formed with an upper flange71extending upward from its top edge and a lower flange72extending downward from its lower edge. The outer side member half80is a sheet-steel press-molded part of a substantially L shape in a front view, a member integrally formed with an upper flange81extending upward from its upper edge and a lower flange82extending downward from its lower edge.

The outer side member half80is put on the inner side member half70to be joined by spot welding the upper flanges71,81and the lower flanges72,82, thereby to form the front side member31of a closed section structure of a substantially rectangular shape in a front view.

The inner and outer side member halves70,80have through holes73,83concentric with one another, through which the first end portion61of the connecting member61extends.

The left connecting member60has a joining flange90joined onto the first end portion61, to be put against and joined to the outer side member half80from laterally outside (right side inFIG. 7).

The joining flange90is a joining member called a neck flange, having a rectangular or circular flange91integrally formed with a tubular neck92. The thickness of the flange91is set greater than that of the inner and outer side member halves70,80, increasing the rigidity. The neck92has an insertion hole93through which the first end portion61of the connecting member60extends.

The first end portion61extending through the joining flange90is welded to the neck92. The first end portion61is inserted through the through holes73,83. The flange91is welded to the outer side member half80, and the end of the first end portion61is welded to the inner side member half70. Thus, the first end portion61of the connecting member60is joined to the front side member31. The welding is MIG welding, for example, for increasing the reliability of the joints.

Since the first end portion61of the connecting member60is attached to the front side member31in a transversely penetrating manner, the mounting position of the connecting member60relative to the front side member31is easily improved in accuracy.

Now, the process of joining the first end portion61of the connecting member60to the front side member31will be described with reference toFIGS. 8A to 8C.

First, as shown inFIG. 8A, the first end portion61of the connecting member60is inserted into the joining flange90, and the joining flange90is set at a predetermined position of depth dimension De from an end61aof the first end portion61. An outer peripheral surface of the first end portion61of the connecting member60is intermittently or continuously welded to an end of the neck92of the joining flange90. Intermittent welding is preferable for preventing welding heat distortion.

Then, as shown inFIG. 8B, the first end portion61is inserted into the through hole83of the outer side member half80from laterally outside (right side in the figure), putting the flange91onto the outer side member half80from laterally outside. Then, the flange91is spot-welded to the outer side member half80.

As shown inFIG. 8C, after inserting the first end portion61into the through hole73of the inner side member half70, the inner side member half70and the outer side member half80are put together. Then, the upper flanges71,81and the lower flanges72,82are spot-welded.

Finally, an outer peripheral surface of the end61aof the first end portion61is intermittently or continuously welded to the inner side member half70, completing the operation of joining the first end portion61of the connecting member60to the front side member31. Intermittent welding is preferable for preventing welding heat distortion.

The operation of welding the upper flanges71,81and the lower flanges72,82and the operation of welding the first end portion61to the inner side member half70may be reversed in order.

The welding operation for the joints between the connecting member60and the front side member31may be performed in stages at different times to prevent welding heat distortion in the front side member31and the connecting member60.

Now, the connecting structure of the second end portion62of the connecting member60will be described with reference toFIGS. 5 to 7andFIGS. 9 to 10.

As shown inFIGS. 6,7,9and10, the second end portion62of the connecting member60is connected to the front upper member38via a bracket100and a stay110.

The bracket100is, as shown inFIGS. 6,7and9, a sheet-steel press-molded part extending horizontally from the drooped portion33of the front upper member38toward the front side member31. Specifically, the bracket100consists of a base portion101welded to the drooped portion33, a support portion102extending from the base portion101toward the front side member31, and flanges103,103extending upward and downward from the upper and lower edges of the support portion102.

The support portion102has a substantially U shape, as viewed in cross-section, bent toward the opposite side of the second end portion62of the connecting member60so as not to interfere with the second end portion62(seeFIG. 9). The upper and lower flanges103,103are in parallel with the first end portion61of the connecting member60.

The stay110is a pipe-like member for attaching the connecting member60of a bent round pipe to the bracket100. Hereinafter, the connecting member60is referred to as a “round pipe60” when appropriate, and the stay110is referred to as a “pipe stay110” when appropriate.

The stay110is a pipe stay consisting of a pair of upper and lower flat-plate flanges111,111for sandwiching the round pipe60slidably along its outer surface63, and a connecting portion112connecting the flanges111,111, and is a sheet-steel press-molded part having a substantially U-shaped cross section opening toward the opening side of the support portion102of the bracket100.

The pair of upper and lower flanges111,111have plate surfaces opposite to one another in parallel. The stay110is positioned relative to the round pipe60in a pipe radial direction. For welding the flanges111,111to the outer surface63of the round pipe60, the flanges111,111are formed with elongate holes113,113, respectively. The elongate holes113,113are formed subparallel with the axially longitudinal center line Lp (seeFIG. 10) of the round pipe60.

As shown inFIGS. 6 and 9, after slidingly positioning the pipe stay110relative to the round pipe60, edges113a,113aforming the elongate holes113,113are welded to the outer surface63of the round pipe60, whereby the stay110is joined to the round pipe60. In joining the round pipe60and the stay110, the elongate holes113,113allow the weld length to be set freely, providing necessary joint rigidity.

The pair of upper and lower flanges111,111have integrally formed joining flanges114,114, respectively, to be put onto and joined to the respective flanges103,103of the bracket100. As shown inFIG. 9, the flanges103,103of the bracket100and the joining flanges114,114of the stay110are joined by spot welding. As a result, the bent round pipe60is easily joined to the front upper member38via the stay110.

Now, the functions of the vehicle front body structure of the above configuration will be described with reference toFIG. 11.

FIG. 11schematically shows the relationship between the front side member31, the front upper member38and the connecting member60on the left side.

The first end portion61of the connecting member60transversely extends through the front side member31in front of the wheel house35(seeFIG. 1). The first end portion61is welded to the both sides it extends through, that is, the inner and outer side member halves70,80of the front side member31. Thus, the simple configuration sufficiently increases the rigidity of a joined portion31bof the front side member31to which the first end portion61of the connecting member60is joined. Details will be described below.

Suppose here that the connecting member60is a cantilever with the first end portion61fixed. The joined portion31bto which the first end portion61is joined is a base portion of the cantilever. When the second end portion62is under a bending load, the joined portion31b(base portion31b) is subjected to the maximum bending moment.

However, since the first end portion61of the connecting member60is joined both to the inner side member half70and to the outer side member half80, the base portion31bhas very large rigidity. The maximum bending moment on the base portion31bis thus received by the front side member31as a whole having a closed cross-section structure.

Since the first end portion61is joined to the outer side member half80via the necked flange90of high rigidity, the load is dispersed into the outer side member half80. This prevents stress concentration at the outer side member half80, ensuring sufficient rigidity of the front side member31as a whole.

When an impact energy En acts on the front upper member38from the front of the body20, the impact energy En is sufficiently transmitted from the front upper member38to the front side member31via the connecting member60and the base portion31bof high rigidity. The front side member31and the front upper member38then plastically deform, thereby sufficiently mitigating the impact energy En acting toward the passenger compartment23(seeFIG. 1). That is, the impact energy En acting on the front upper member38is absorbed not only by the front upper member38but also by the front side member31sufficiently.

With this simple structure, an impact energy En at an offset impact on the front of the body20is sufficiently dispersed into the front side member31and the front upper member38, thus being efficiently absorbed. Then, the impact energy En acting toward the passenger compartment23(seeFIG. 1) is mitigated.

The connecting member60connects a front portion of the front side member31and a front portion of the front upper member38, thus increasing the rigidity of the body20front part. As a result, the rigidity of the body20as a whole including a passenger compartment23part is increased.

The right connecting member60and its connecting structure are identical to the left connecting member60and its connecting structure, and have the same functions and effects. Specifically, the right connecting member60has a first end portion61transversely extending through the right front side member31, welded to both sides it extends through, that is, inner and outer side member halves70,80, and has a second end portion62joined to the right front upper member38.

Each connecting member60shown in this embodiment is a bent round pipe, but the present invention is not limited thereto. It may be a hollow or solid linear member of a round cross section or a square cross section.

As described above, the vehicle front body structure of the present invention is useful especially for automobiles having right and left front side members31,31and right and left front upper members38,38.

Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.