Automobile frontbody structure

Abstract: An outer reinforcement panel supports a toe board (2) which connects a front frame (1) and a floor panel (3) from the undersurface of the toe board and an inner reinforcement panel (9) supports the toe board from the topsurface of the toe board. On the outer reinforcement panel, three frames (81-83) having U-shaped cross sections are integrally formed with the outer reinforcement panel in a radial manner and these frames are welded at the ends thereof to primary body skeletons such as a side sill, a wheel house, a side frame and the like. Similarly, on the inner reinforcement panel, two frames (91,92) having inverse U-shaped cross sections are integrally formed with the inner reinforcement panel in a radial manner and these frames are also welded at the ends thereof to those primary body skeletons. Thus, a plurality of frames having closed cross sections are formed on inner and outer surfaces of the toe board and the floor panel. Even in the event of an offset collision or an oblique collision, since an impact energy is transmitted well diffusively to these body skeletons through these frames, the damage to passengers can be minimized.

Description: BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a frontbody structure for an automobile and more particularly to a frame structure of a frontal portion of an automobile body. 2. Description of the prior art In a frame structure of the front portion of a conventional automobile, respective rear ends of left and right front frames extending longitudinally along respective left and right side walls of an engine room are connected at an inclined portion of a toe board partitioning between the engine room and a passenger compartment with front ends of left and right side frames connected to the underneath of a floor, in the event of a collision, so as to diffusively transfer an impact load inputted from the front frame to the floor and the like through the toe board and the side frame. A drawback of this frame structure is a difficulty in transferring the impact load to the side frame in a stable manner in the event of a collision and as a result it has such a problem that a lower curved portion of the toe board is deformed being projected in the direction of the passenger compartment due to a concentrated impact load. Hitherto, numerous approaches have been made to increase the rigidity of the connecting portion of the front frame with the toe board. For example, Japanese Utility Model Application Laid-Open No. Jitsu-Kai-Shou 63-43881 discloses an approach in which a reinforcement member is secured from the passenger compartment side to the lower curved portion of the toe board at the connecting portion of the front frame with the toe board so as to be connected at one end thereof with an upper central portion of the toe board and at the other end thereof with the side frame. This approach contemplates that the reinforced curved portion of the toe board enable a diffusion of the impact load transmitted from the front frame to the toe board toward the side frame and the floor tunnel. JP-A-9175434 discloses a frontbody structure for a vehicle having a pair of left and right front frames (2) extending longitudinally, a toe board (1) rigidly connected to a rear end of said front frame, and a floor panel (implicit), comprising: a pair of left and right inner reinforcement panels (12a), each said inner reinforcement panel rigidly secured from above to a top surface of said toe board and rigidly secured from above at a rear end thereof to a top surface of said floor panel according to the preamble of claim 1. However, this prior art such as exemplified by the aforesaid approach is still inadequate in the diffusion of the impact load at the event of an offset collision or an oblique collision. Yet, an additional use of the reinforcement member leads to a further increase of the vehicle weight and this is retrogressive in terms of the weight reduction. Accordingly, the present invention has been made with a view to substantially eliminating the above discussed problems inherent in the prior art frontbody structure and its object is to provide an improved frontbody structure of an automobile having an increased rigidity. To achieve this object, the present invention provides a vehicle frame structure for comprising: a pair of left and right front frame members extending longitudinally, a toe board rigidly connected to a rear end of said front frame members, a floor panel extending in a widthwise direction of said vehicle, a pair of left and right wheel housings, a pair of left and right side sills extending in a longitudinal direction of said vehicle, a center tunnel extending longitudinally in a central region of said vehicle, and a pair of left and right side frames extending in a longitudinal direction of said vehicle between said centre tunnel and side sill, characterised by a branched frame structure including: a pair of left and right outer reinforcement panels, each of said outer reinforcement panels being rigidly secured from below to an undersurface of said toe board and rigidly secured at its front end to the rear end of said each front frame member, and also having its rear end rigidly secured from below to the undersurface of said floor panel; a pair of left and right inner reinforcement panels, each of said inner reinforcement panels being rigidly secured from above to the upper surface of said toe board and rigidly secured from above at a rear end thereof to an upper surface of said floor panel, and three rearwardly extending curved prong like frame members which comprise: a first outer frame member having a closed cross section and formed integrally with each said outer reinforcement panel, said first outer frame having a rear end rigidly secured to each said wheel housing and each said side sill, respectively; a second outer frame member having a closed cross-section and formed integrally with each said outer reinforcement panel, said second outer frame member having a rear end secured to the side frame; a third outer frame member having a closed cross section and formed integrally with each said outer reinforcement panel, said third outer frame member having a rear end rigidly secured to said center tunnel ; and a first inner frame member having a closed cross section and formed integrally with each said inner reinforcement panel, said first inner frame member having a rear end rigidly secured to each said wheel housing and each said side sill, respectively. BRIEF DESCRIPTION OF THE DRAWINGS The object and feature of the present invention will become more clearly understood from the following description of a preferred embodiment thereof with reference to the accompanying drawings, in which: Fig. 1a is a fragmentary perspective view of a front body structure as viewed from the rear center of the passenger compartment; Fig. 1b is a fragmentary perspective view of a front body structure as viewed from the front of the vehicle; Fig. 2a is a fragmentary sectional view taken along the line A-A of Fig. 1a; and Fig. 2b is a fragmentary sectional view taken along the line B-B of Fig. 1a. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to Fig. 1a, reference numerals 1, 1 are left and right front frames provided longitudinally along left and right side walls of an engine room. The front frames 1, 1 are batt-welded at the rear ends thereof respectively to a curved portion ranging from a vertical portion of a toe board 2 for partitioning between the engine room and the passenger compartment to its rearwardly slanted portion. The toe board 2 is reinforced by an outer reinforcement panel 8 and an inner reinforcement panel 9 from its curved portion to its connecting portion with a floor panel 3. Further, the front frame 1 is connected at the rear ends thereof with the front end of the outer reinforcement panel 8. The outer reinforcement panel 8 is formed in such a way that its width becomes gradually broader as it goes rearward and has a front frame connecting portion 8a connecting the rear end of the front frame 1 with the outer reinforcement panel 8 such that the outer reinforcement panel 8 enclose the front frame 1 from below. Further, the outer reinforcement panel 8 is rigidly secured at the rear end thereof to the toe board 2 and the floor panel 3, respectively. Further, three outer frames having U-shaped cross sections are formed integrally with the outer reinforcement panel 8. That is, a first outer frame 81, a second outer frame 82 and a third outer frame 83 are formed being pronged slightly downward of the front frame connecting portion 8a backward in a radial manner. The first outer frame 81 is spot-welded at the rear end thereof to a wheel house 4 and the lower end of a front pillar 7 (front end of a side sill 5), respectively, the second outer frame 82 is spot-welded at the rear end thereof to a side frame 6 which is connected with the floor panel 3 from underneath and the third outer frame 83 is spot-welded at the rear end thereof to the front bottom portion of a floor tunnel 30 which is formed at the central portion in the widthwise direction of the floor panel 3. On the inner reinforcement panel 9, a first inner frame 91 with an inverse U-shaped cross section and a second inner frame 92 with an inverse U-shaped cross section are formed integrally with the inner reinforcement panel 9 in the same manner as in the case of the outer reinforcement panel 8. The first inner frame 91 serves as connecting the rear end of the front frame 1 with the wheel house 4 and the front end of the side sill 5, respectively and the second inner frame 92 serves as connecting the rear end of the front frame 1 with the front end of the side frame 6. Specifically, as illustrated in Figs. 2a and 2b, the first inner frame 91 is spot-welded at the rear end thereof to the wheel house 4 and the inner panel of the side sill 5, respectively. Further, the second inner frame 92 is spot-welded at the front portion thereof to the vertical portion of the toe board 2 and it is spot-welded at the rear end thereof to the side frame 6 with the floor panel 3 between. In thus constituted structure, a plurality of outer and inner frames having respective closed cross sections are formed in a radial manner on both surfaces of the toe board 2 and the floor panel 3. Accordingly, an impact load inputted from the front end of the front frame 1 is widely transmitted through these frames to a plurality of primary body skeleton members such as the wheel house 4, the side sill 5, the side frame 6, the floor panel 3 and the center tunnel 30. Further, even in case of an offset collision or an oblique collision, the impact load is transmitted and absorbed effectively because it spreads radially through these frames. Further, since respective flat portions between two opposite frames function as doublers (two laminated sheets), those further raise the rigidity of the toe board 2 and the floor panel 3. According to the present invention, a plurality of frames having closed cross sections are formed rearwardly in a radial manner by rigidly connecting the outer reinforcement panel to the inner reinforcement panel with the toe board and the floor panel between and these frames connect the rear end of the front frame with the primary body structures such as side sills, side frames, floor tunnel and the like. Thus formed frontbody structure brings not only a great increase of the rigidity of the toe board, the floor panel and the surrounding components, but also reductions of the number of components and labor hours. Further, since the radially formed frames, even in the event of an offset collision or an oblique collision, diffusively transmit the impact load to the primary body skeletons, the deformation of the toe board and the floor panel can be minimized, this leading to small damages of occupants. While the presently preferred embodiment of the present invention has been shown and described, it is to be understood that this disclosure is for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claim.

Claims: A vehicle frame structure for comprising: a pair of left and right front frame members (1, 1) extending longitudinally, a toe board (2) rigidly connected to a rear end of said front frame members (1), a floor panel (3) extending in a widthwise direction of said vehicle, a pair of left and right wheel housings (4), a pair of left and right side sills (5, 5) extending in a longitudinal direction of said vehicle, a center tunnel (30) extending longitudinally in a central region of said vehicle, and a pair of left and right side frames (6.6) extending in a longitudinal direction of said vehicle between said centre tunnel (30) and side sill (5), characterised by a branched frame structure including: a pair of left and right outer reinforcement panels (8, 8), each of said outer reinforcement panels being rigidly secured from below to an undersurface of said toe board (2) and rigidly secured at its front end to the rear end of said each front frame member (1,1), and also having its rear end rigidly secured from below to the undersurface of said floor panel (3); a pair of left and right inner reinforcement panels (9, 9), each of said inner reinforcement panels being rigidly secured from above to the upper surface of said toe board (2) and rigidly secured from above at a rear end thereof to an upper surface of said floor panel (3), and three rearwardly extending curved prong like frame members which comprise: a first outer frame member (81) having a closed cross section and formed integrally with each said outer reinforcement panel (8), said first outer frame (81) having a rear end rigidly secured to each said wheel housing and each said side sill, respectively; a second outer frame member (82) having a closed cross-section and formed integrally with each said outer reinforcement panel (8), said second outer frame member having a rear end secured to the side frame 6; a third outer frame member (83) having a closed cross section and formed integrally with each said outer reinforcement panel (8), said third outer frame member (83) having a rear end rigidly secured to said center tunnel (30); and a first inner frame member (91) having a closed cross section and formed integrally with each said inner reinforcement panel (9), said first inner frame member (91) having a rear end rigidly secured to each said wheel housing (4) and each said side sill (5), respectively. A frame structure according to claim 1, wherein said branched frame structure further comprises a second inner frame member (92) having a closed cross section and formed integrally with each of the inner reinforcement panel (9), the second inner frame member having a rear end rigidly secured to each of said side frames (6).

Inventors: MASUDA TOSHIO, MASUDA, TOSHIO, Masuda, Toshio, Fuji Jukogyo K.K.
Applicants: FUJI HEAVY IND LTD, FUJI JUKOGYO KABUSHIKI KAISHA
Application year: 1998
Main classification: B62D25
IPC codes: B62D25