The present invention relates to a vehicle-body structure of an automotive vehicle which comprises a frame provided at a side portion of a vehicle body to extend in a vehicle longitudinal direction, such as a front side frame or a rear side frame.
In general, the front side frame or the rear side frame which extends in the vehicle longitudinal direction is provided at the side portion of the vehicle body, and these side frames contribute to ensuring the vehicle-body rigidity and absorbing a collision load.
When a vehicle has a so-called small overlap collision at its front side in which the collision load is not inputted to the front side frame, the collision load is directly inputted to a front pillar of the vehicle, so that a vehicle body may deform greatly.
A vehicle compartment (cabin) is required to be protected properly for ensuring a cabin space. Herein, while there are provided a front pillar, a roof side rail, a side sill, and a door as members for protecting the vehicle compartment against the collision at a vehicle-body side, the door is an openable member and therefore the connectivity of the door is rather low, so that a cabin-protecting structure with the front pillar and the side sill is generally applied.
For example, when the vehicle has an offset collision in which a collision point is located on an outward side, in a vehicle width direction, of the front side frame, like the collision with a small overlap of 25% or less, the sufficient load absorption may not be expected at the front side frame. Therefore, it is desired that a load absorption portion is provided in back of a front end of the front side frame on the outward side, in the vehicle width direction, of the front side frame, or a vehicle body is controlled to be displaced having a lateral slide. In a case of providing the load absorption portion, while it may be considered that the front pillar is set to be thick (big), this thick front pillar may not only increase the weight but deteriorate a front view. This problem may happen to a vehicle-body rear portion as well as the vehicle-body front portion.
Meanwhile, US Patent Application Publication No. 2004/0195862 A1 discloses a structure in which there are provided a pair of side members, each of which has a bifurcated part comprising an outward side portion and an inward side portion, a bumper reinforcement is provided to extend in the vehicle width direction between respective front end portions of the right-and-left side members, and first and second notches are formed at a specified portion of the bifurcated side member, whereby a front end portion of the side member can be controlled to interfere with a powertrain in a vehicle collision, thereby generating a lateral-slide load.
Since the conventional structure disclosed in the above-described patent document is configured to receive the collision load by utilizing blocking of an engine or transmission, the lateral-slide load is generated at the timing the front end portion of the side member which is spaced apart from the powertrain before the vehicle collision comes to contact the powertrain, so that there is a problem that generation of the lateral-slide load may get delayed improperly. Further, since the powertrain is generally connected to the sub frame via a bush, there is another problem that the load transmission may get delayed.
Further, US Patent Application Publication No. 2012/0248820 A1 discloses a structure in which there is provided a branch frame which extends obliquely forward and outward from a middle portion, in the vehicle longitudinal direction, of the front side frame, and the offset-collision load is received, in the vehicle width direction, at a joint portion of the branch frame and the front side frame, thereby generating the lateral-slide load.
However, since the conventional structure disclosed in the second patent document is configured to receive the collision load at the above-described joint portion positioned at the longitudinal-middle portion of the front side frame, there is a problem that the position of the joint portion is located so rearward that the design flexibility may be improperly low.