1. Field of the Invention
The present invention relates to a body structure for vehicle bodies, and in particular to a front body structure forming a front portion of a passenger compartment for automobiles that are one of typical vehicles.
2. Description of Related Art
Recently various kinds of so-called hydro-forming have been proposed as one type of methods of forming metal members in the automobile industries. Hydro-forming is a molding or forming method to form a high tensile strength steel pipe to a given shape. The pipe member is placed in a die cavity and filled with a fluid such as water or oil. The pipe member is expanded by pressurizing the fluid until the pipe member is deformed to an external shape reflecting the contour of the die cavity. Such hydro-forming is known from, for example, Japanese a Unexamined Patent Publications Nos. 10-218017 and 11-235963 as applied to forming a reinforcement having a rectangular closed cross-section for a side sill or a center pillar of a vehicle body. In the hydro-forming, a pipe member for a reinforcement of a side sill is placed between upper and lower dies between which a cavity having a contour identical to an external shape of the reinforcement is formed, and then, pressurizing fluid is introduced into the pipe member so as to expand the pipe member until the pipe member is deformed to a shape reflecting the given contour of the cavity. The reinforcement thus formed is put in a follow side frame of a vehicle body and welding to the side frame. According to another example, a reinforcement having a rectangular closed cross-section, which is used to reinforce a center pillar extending downward from a roof side rail, is formed from a pipe member by the hydro-forming. The reinforcement is put in an internal space of the center pillar comprising a center pillar outer and a center pillar outer.
The hydro-forming can provides a pipe member with any external shape according to the given contour of the die cavity. By using this technology it becomes possible to obtain more lightened but more rigid structural members having various desired shapes as compared with similar members that are made by welding a plurality of stamped steel plates.
Generally a cowl structure located in front of a cabin or passenger compartment of an automobile that is a typical one of vehicles is an important structural part for safety because the cowl structure is not only contributory to ensure a body rigidity but also works as a base which mounts thereon a steering shaft and an air-bag that require high-accuracy and delicate adjustment in fitting position. However, the cowl structure needs a large number of parts that are usually complicated in shape, so that many restraints are put on designing and assembling the parts. Although, it is desirable to form the cowl structure from a reduced number of parts formed by the hydro-forming in light of simplifying assembling the parts to a cowl structure, nevertheless, a more reliable structure is needed because the cowl structure is of very importance in the terms of sufficient rigidity and safety of the vehicle body.
An object of the present invention is to provide a front body structure for vehicles which provides the front body with light weight and high rigidity.
The above object of the present invention is accomplished by a front body structure that comprises a dash panel separating a cabin or passenger compartment from the remaining part of a vehicle body, a dash panel member extending in a transverse direction of the vehicle body which is welded to the dash panel or another member disposed in the close vicinity of the dash panel, and an instrument panel member extending in the transverse direction in the close vicinity of the dash panel and supported at opposite ends thereof by side panels. The dash panel member and/or the instrument panel member are formed from a hollow pipe formed by hydro-forming. Each of the dash panel member and the instrument panel member has opposite ends welded to the side panels of the vehicle body, respectively.
According to the preferred embodiment of the present invention, a pipe member as the instrument panel member has opposite ends welded to the side panels having door openings, respectively, and a generally U-shaped central portion opening upward and welded to a floor panel at a bottom thereof.
According to another preferred embodiment of the present invention, a pipe member formed as the dash panel member has opposite end portions, each of which extends downward on the inner wall of the side panel along the door opening so that the end of the dash panel member is welded to the dash panel member in the close vicinity of the side panel, and a pipe member formed as the instrument panel member has opposite ends welded to the dash panel member in the close vicinity of the side panels and a generally U-shape central portion opening upward and welded to the floor panel at a bottom thereof.
The instrument panel member may be provided with brackets welded thereto for mounting a steering shaft and an air-bag on a passengers seat side on an intermediate portion of the instrument panel member between the generally U-shape central portion and one of the opposite ends of the instrument panel member on the passenger seat side. Further, the dash panel member may be provided with a cowl member extending in the transverse direction of the vehicle body and having a closed cross-section.
The front body structure of the present invention, including at least one of the dash panel member and the instrument panel member which are formed from a pipe member by hydro-forming, is comprised by an decreased number of parts by spot-welding them at a reduced number of points. This provides the front body with lighter weight and higher structural rigidity as compared with prior art front bodies. In consequent, the front body structure realizes firm and reliable installation of brackets for mounting steering shaft and an air-bag to one of the intermediate portions of the instrument panel member.
The front body structure of the present invention, including the dash panel member formed from a pipe member which as the end portion extending downward along the door opening of the side panels and welded to the side sill, provides a wide area for welding. This wide area of welding provides the front body with high structural rigidity.
The front body structure of the present invention, including the dash panel member and the instrument panel member formed from pipe members, respectively, which are welded to the inner wall of the vehicle body, improves the structural rigidity of the vehicle body and provides a light weighted front body due to a reduced number of parts.
Furthermore, the front body structure of the present invention, including the dash panel member formed from a pipe member ensures a sufficient structural rigidity of the front body. This increases the degree of designing a cowl structure because the dash panel member formed from a pipe member provides the front body with a high rigidity.