Vehicle lower structure

A vehicle lower structure includes: a passenger compartment front wall lower portion separating a vehicle-body front portion and a passenger compartment; and a tunnel portion extending toward a vehicle rear side from a central part of the passenger compartment front wall lower portion in a vehicle width direction and projecting toward a vehicle upper side relative to a vehicle body floor. The tunnel portion includes: a rear tunnel constituent portion, a sectional shape thereof perpendicular to an extending direction of the tunnel portion being a semipolygonal shape; and a front tunnel constituent portion, the front tunnel constituent portion being adjacent to a vehicle front side of the rear tunnel constituent portion, a sectional shape thereof perpendicular to the extending direction of the tunnel portion being a semipolygonal section and the number of corners thereof being larger than the number of corners of the rear tunnel constituent portion.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2013-252529 filed on Dec. 5, 2013 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vehicle lower structure.

2. Description of Related Art

There has been known a structure in which a tunnel portion is provided in a central part of a vehicle lower portion in a vehicle width direction (for example, see Japanese Patent Application Publication No. 2002-362419 (JP 2002-362419 A), Japanese Patent Application Publication No. 2013-184569 (JP 2013-184569 A)). In such a structure, a reinforcing member may be provided on a vehicle front side end of the tunnel portion. In such a configuration, a load from a vehicle-body front side can be stably supported by a front part of the tunnel portion.

However, weight increases due to addition of the reinforcing member in such a structure.

SUMMARY OF THE INVENTION

The present invention provides a vehicle lower structure that is able to stably support a load from a vehicle body front side by a front part of a tunnel portion, while restraining an increase in weight.

An aspect of the present invention relates to a vehicle lower structure. The vehicle lower structure includes: a passenger compartment front wall lower portion constituting a lower part of a passenger compartment front wall separating a vehicle-body front portion and a passenger compartment; and a tunnel portion extending toward a vehicle rear side from a central part of the passenger compartment front wall lower portion in a vehicle width direction and projecting toward a vehicle upper side relative to a general portion of a vehicle body floor. The tunnel portion includes: a rear tunnel constituent portion provided as a constituent portion that does not include a vehicle front side end of the tunnel portion, a sectional shape of the rear tunnel constituent portion perpendicular to an extending direction of the tunnel portion is a semipolygonal shape; and a front tunnel constituent portion provided as a constituent portion including the vehicle front side end of the tunnel portion, the front tunnel constituent portion being adjacent to a vehicle front side of the rear tunnel constituent portion, a sectional shape of the front tunnel constituent portion perpendicular to the extending direction of the tunnel portion is a semipolygonal shape and the number of corners of the semipolygonal shape of the front tunnel constituent portion is larger than the number of corners of the semipolygonal shape of the rear tunnel constituent portion.

According to the above aspect, the tunnel portion includes the front tunnel constituent portion including a vehicle front side end of the tunnel portion, and the rear tunnel constituent portion adjacent to a vehicle rear side of the front tunnel constituent portion, and respective sectional shapes thereof perpendicular to the extending direction of the tunnel portion are a semipolygonal shape. Here, the number of corners of the front tunnel constituent portion is set larger than the number of corners of the rear tunnel constituent portion. As a result, the front tunnel constituent portion is set to have higher rigidity than the rear tunnel constituent portion. In view of this, when a collision load is input to the tunnel portion from a side of the passenger compartment front wall lower portion, it is possible to stably support the load by the front tunnel constituent portion.

As described above, according to the vehicle lower structure according to the aspect of the present invention, it is possible to yield such an excellent effect that a load from a vehicle body front side can be stably supported by a front part of a tunnel portion, while restraining an increase in weight.

DETAILED DESCRIPTION OF EMBODIMENTS

Configuration of Embodiment

The following describes a vehicle lower structure according to one embodiment of the present invention with reference toFIGS. 1 and 2. Note that an arrow FR shown appropriately in each figure indicates a vehicle front side, an arrow UP indicates a vehicle upper side, and an arrow W indicates a vehicle width direction.

FIG. 1is a perspective view illustrating part of a vehicle lower structure10and its peripheral part thereof according to the present embodiment. Further,FIG. 2is a sectional side view illustrating part of the vehicle lower structure10and its peripheral part thereof according to the present embodiment, when viewed from a vehicle lateral side.

As illustrated inFIG. 1, an engine compartment (also referred to as “engine room”)14is disposed in a vehicle-body front portion12of an automobile A. An engine unit16is placed in the engine compartment14. Note that the engine unit16is simplified in the figure. The engine unit16generates a driving force for the automobile A to run. An output shaft of the engine unit16is a drive shaft (not shown) extending in the vehicle width direction. The drive shaft is connected to front wheels (not shown) and the drive shaft is a member that transmits a driving force to the front wheels.

Further, a rear part of the engine unit16is supported, via an engine mounting (a mounting member)18, by a vehicle-body constituent portion (not shown) of the vehicle-body front portion12in a vibration inhibiting manner. The engine mounting18is placed in the engine compartment14. Note that a given part of the engine unit16except the rear part thereof is also supported, via other engine mountings (not shown), by the vehicle-body constituent part (not shown) of the vehicle-body front portion12in a vibration inhibiting manner.

Further, in the engine compartment14, a steering gear box20is provided on a vehicle rear side of the engine unit16so as to extend in the vehicle width direction. The steering gear box20is connected to a steering wheel (not shown), and is also connected to front wheels (not shown). This enables steering by the steerage of the steering wheel.

The vehicle-body front portion12(the engine compartment14) and a passenger compartment22are separated from each other by a dash panel body portion26serving as a passenger compartment front wall in the dash panel24. The dash panel body portion26includes an up-down panel portion26A generally hanging down from an upper end of the dash panel body portion26in a generally up-down panel shape. Further, a toeboard portion26B having an inclined plate shape bent downward toward a vehicle rear side from a lower end of the up-down panel portion26A so as to be inclined toward a vehicle lower side and the vehicle rear side is formed, and the toeboard portion26B constitutes a lower end side of the dash panel body portion26. A dash panel body lower portion26U as a passenger-compartment-front-wall lower portion constituting a lower part of the dash panel body portion26is constituted by a lower end of the up-down panel portion26A and the toeboard portion26B.

A notch portion26K opened toward the vehicle lower side is formed in a central part of the dash panel body lower portion26U in the vehicle width direction. An edge of the notch portion26K on its upper side is formed in a lower end of the up-down panel portion26A, and an opening of the notch portion26K on its lower side is formed in a lower end of the toeboard portion26B.

A front end of a floor panel28as a vehicle body floor is joined, by spot welding or the like, to an edge of the dash panel body lower portion26U. The floor panel28constitutes a floor of the passenger compartment22, and includes general portions28A on both right and left sides, and a floor tunnel portion28B in a central part thereof in the vehicle width direction.

An outer end of the general portion28A of the floor panel28in the vehicle width direction is joined to a rocker38. The rocker38is provided in a lower end of a vehicle-body side portion so as to extend in a vehicle longitudinal direction. Further, a front end of the floor tunnel portion28B is joined to an edge side of the notch portion26K of the dash panel body lower portion26U via a flange. The floor tunnel portion28B is provided in the central part of the dash panel body lower portion26U in the vehicle width direction so as to extend toward the vehicle rear side therefrom, and projects toward the vehicle upper side relative to the general portions28A of the floor panel28. Thus, the floor tunnel portion28B constitutes a tunnel portion30solely.

The tunnel portion30constitutes part of a body framework portion having a predetermined offset yield strength with respect to a collision load. No reinforcing member such as a reinforcement is attached to the tunnel portion30in the present embodiment. The tunnel portion30includes a rear tunnel constituent portion34, which is a constituent portion that does not include a vehicle front side end of the tunnel portion30, and also includes a front tunnel constituent portion32, which is a constituent portion that includes the vehicle front side end of the tunnel portion30. The front tunnel constituent portion32is formed adjacent to a vehicle front side of the rear tunnel constituent portion34(in a successive manner). Further, the rear tunnel constituent portion34includes a vehicle rear side end of the tunnel portion30.

The rear tunnel constituent portion34includes an upper wall portion34A, and paired right and left side wall portions34B each hanging down from each outer end of the upper wall portion34A in the vehicle width direction, and a sectional shape thereof perpendicular to an extending direction of the tunnel portion30is a semipolygonal shape. A lower end of the side wall portion34B is connected to an inner end of the general portion28A of the floor panel28in the vehicle width direction and to an inner end of the toeboard portion26B in the vehicle width direction.

The rear tunnel constituent portion34is set to have two (even number of) corners (in other words, internal corners of the semipolygonal shape in the sectional shape) made, inside the semipolygonal shape, by the upper wall portion34A and the paired right and left side wall portions34B adjacent thereto. Note that two corners bent outwardly in the vehicle width direction are formed on lower sides of the paired right and left side wall portions34B. Further, that sectional shape of the rear tunnel constituent portion34which is perpendicular to the extending direction of the tunnel portion30is a bilaterally symmetrical shape. A linear edge line portion L3serving as a boundary portion between the upper wall portion34A and each of the paired right and left side wall portions34B extends in the vehicle longitudinal direction.

The front tunnel constituent portion32includes: an upper wall portion32A set on the same plane as the upper wall portion34A of the rear tunnel constituent portion34; side wall portions32B set on the same plane as the side wall portions34B of the rear tunnel constituent portion34; and connecting wall portions32C for connecting the upper wall portion32A to the side wall portions32B. That is, the front tunnel constituent portion32is configured such that its sectional shape perpendicular to the extending direction of the tunnel portion30is a semipolygonal shape, and the number of corners is set larger than the number of corners of the rear tunnel constituent portion34. A lower end of the side wall portion32B is connected to the inner end of the toeboard portion26B in the vehicle width direction.

The front tunnel constituent portion32is set to have four (even number of) corners (in other words, internal corners of the semipolygonal shape in the sectional shape) made, inside the semipolygonal shape, by the upper wall portion32A and the connecting wall portions32C and by the connecting wall portions32C and the side wall portions32B. Note that two corners bent outwardly in the vehicle width direction are formed on lower sides of the paired right and left side wall portions32B. Further, that sectional shape of the front tunnel constituent portion32which is perpendicular to the extending direction of the tunnel portion30is a bilaterally symmetrical shape.

The connecting wall portion32C is formed in a triangular shape in which a up-donw-panel-portion-26A side of the dash panel body portion26is a base and a front end side of the edge line portion L3of the rear tunnel constituent portion34is a vertex, and a base side (the up-down-panel-portion-26A side of the dash panel body portion26) is inclined outwardly in the vehicle width direction toward the vehicle lower side. Hereby, that sectional shape of the front tunnel constituent portion32which is perpendicular to the extending direction of the tunnel portion30is formed so as to gradually follow the sectional shape of a vehicle front side end of the rear tunnel constituent portion34(the sectional shape perpendicular to the extending direction of the tunnel portion30), as it goes toward the vehicle rear side. A linear edge line portion L1serving as a boundary portion between the upper wall portion32A and the connecting wall portion32C is inclined outwardly in the vehicle width direction toward the vehicle rear side, and is continuous with a front end of the edge line portion L3of the rear tunnel constituent portion34. Further, a linear edge line portion L2serving as a boundary portion between the side wall portion32B and the connecting wall portion32C is inclined upward in a vehicle up-down direction toward the vehicle rear side, and is continuous with the front end of the edge line portion L3of the rear tunnel constituent portion34.

Further, as illustrated inFIG. 2, a boundary portion (a position, in the vehicle longitudinal direction, of an intersection X where the edge line portions L1, L2, L3intersect with each other) between the front tunnel constituent portion32and the rear tunnel constituent portion34is set to a position on the vehicle front side relative to a seat36on which an occupant sits in the passenger compartment22.

Operation/Working-Effects of Embodiment

Operation/working-effects of the embodiment are described below.

As illustrated inFIG. 1, in the present embodiment, the number of corners of the front tunnel constituent portion32is set larger than the number of corners of the rear tunnel constituent portion34. In view of this, the front tunnel constituent portion32is set to have more edge line portions than the rear tunnel constituent portion34, so that its rigidity increases. Therefore, when a collision load F is input into the tunnel portion30via the dash panel body lower portion26U from the engine unit16or the like in the engine compartment14at the time of a front end collision, it is possible to stably support the collision load F by the front tunnel constituent portion32. Further, since a rigid difference is set between the front tunnel constituent portion32and the rear tunnel constituent portion34, when a collision load F of a predetermined value or more is input into the tunnel portion30from a dash-panel-body-lower-portion-26U side, the load is concentrated on the boundary portion (mainly, the intersection X where the edge line portions L1, L2, L3intersect with each other) between the front tunnel constituent portion32and the rear tunnel constituent portion34, thereby making it possible to deform the tunnel portion30by a stable deformation mode with the boundary portion as an origin of the deformation. Hereby, an impact is absorbed effectively.

Here, supplementary explanation is given with a comparative structure as follows. In a tunnel portion according to the comparative structure in which a sectional shape perpendicular to its extending direction is generally reverse U-shaped, for example, when a deformable bead to serve as an origin of deformation at the time of a front collision is formed in a front end of the tunnel portion, rigidity of the front end of the tunnel portion is decreased because of the deformable bead. On the other hand, in the present embodiment, even if the origin of deformation is set, such a decrease in rigidity does not occur, and it is possible to set the front tunnel constituent portion32to have high rigidity.

Further, in the present embodiment, the sectional shape of the front tunnel constituent portion32is formed so as to gradually follow the sectional shape of the vehicle front side end of the rear tunnel constituent portion34as it goes toward the vehicle rear side, and the edge line portions L1, L2of the front tunnel constituent portion32are continuous with the edge line portion L3of the rear tunnel constituent portion34. In view of this, when a collision load F is input into the front tunnel constituent portion32from the dash-panel-body-lower-portion-26U side, the collision load F is effectively transmitted to the rear tunnel constituent portion34from the front tunnel constituent portion32mainly via the edge line portions L1, L2, L3as a load transfer passage (see arrows a, b, c). According to the vehicle lower structure of the present embodiment, when a collision load is input at the time of a front end collision of the vehicle, such an excellent effect can be obtained that the load can be effectively transmitted from the front tunnel constituent portion to the rear tunnel constituent portion.

Further, as illustrated inFIG. 2, in the present embodiment, the boundary portion (the position, in the vehicle longitudinal direction, of the intersection X where the edge line portions L1, L2, L3intersect with each other) between the front tunnel constituent portion32and the rear tunnel constituent portion34, that is, a rigidity change part in the tunnel portion30, is set to a position on the vehicle front side relative to the seat36on which an occupant sits in the passenger compartment22. In view of this, when a collision load F of a predetermined value or more is input into the tunnel portion30via the dash panel body lower portion26U from a vehicle-body-front-portion-12side at the time of a front end collision, the load is concentrated on the boundary portion (mainly, the intersection X where the edge line portions L1, L2, L3intersect with each other) between the front tunnel constituent portion32and the rear tunnel constituent portion34in the tunnel portion30, so that the tunnel portion30is deformed stably in a position on the vehicle front side relative to the seat36with the boundary portion as the origin of the deformation. According to the vehicle lower structure of the present embodiment, such an excellent effect can be yielded that, when a collision load of a predetermined value or more is input at the time of a front end collision of the vehicle, the tunnel portion can be stably deformed in a position on the vehicle front side relative to the seat.

Note that, as illustrated inFIG. 1, those sectional shapes of the front tunnel constituent portion32and the rear tunnel constituent portion34which are perpendicular to the extending direction of the tunnel portion30are bilaterally symmetrical shapes. Hereby, it is possible to transmit the collision load F from the vehicle-body-front-portion-12side toward the vehicle rear side in a good right and left balance.

As described above, according to the vehicle lower structure10of the present embodiment, it is possible to stably support a load from the vehicle-body-front-portion-12side by the front part of the tunnel portion30, while restraining an increase in weight. Further, in the present embodiment, it is possible to achieve a compact body structure.

Further, in the present embodiment, those sectional shapes of the front tunnel constituent portion32and the rear tunnel constituent portion34which are perpendicular to the extending direction of the tunnel portion30are bilaterally symmetrical shapes, and, in addition to that, the number of internal corners of the semipolygonal shape in each of the sectional shapes is set to an even number. In view of this, top faces of the upper wall portions32A,34A are set to be horizontal, so that inner members such as a console box (not shown) can be provided easily, for example, thereby making it possible to effectively use a top face of the tunnel portion30.

Supplementary Description of Embodiment

Note that, as a modification of the embodiment, the tunnel portion may be configured such that: a dash tunnel portion is formed so as to extend from an opening edge of a notch portion (26K) of a dash panel (24) toward an inner side of a passenger compartment22and to integrally project toward the vehicle upper side from inner ends of right and left toeboard portion (26B) in the vehicle width direction; a floor tunnel portion is formed so as to integrally project toward the vehicle upper side from inner ends of general portions (28A) of a floor panel (28) in the vehicle width direction; and a rear end of the dash tunnel portion is joined to a front end of the floor tunnel portion. In this case, for example, a part constituted by the floor tunnel portion may be assumed a rear tunnel constituent portion having the same number of corners as the rear tunnel constituent portion34of the above embodiment, and a part constituted by the dash tunnel portion may be assumed a front tunnel constituent portion having the same number of corners as the front tunnel constituent portion32of the above embodiment. Further, in this case, an edge line portion of the front tunnel constituent portion and an edge line portion of the rear tunnel constituent portion are preferably continuous with each other similarly to the above embodiment. However, the edge line portion of the front tunnel constituent portion may be entirely or partially discontinuous with the edge line portion of the rear tunnel constituent portion.

Further, as a modification of the embodiment, the boundary portion between the front tunnel constituent portion and the rear tunnel constituent portion may not be set in a position on the vehicle front side relative to a front end of the seat on which the occupant sits in the passenger compartment.

Further, as a modification of the embodiment, the front tunnel constituent portion may be set such that the number of internal corners of the semipolygonal shape of the section thereof perpendicular to the extending direction of the tunnel portion is three, five, six or the like number except four and is set to the number larger than the number of internal corners of the semipolygonal shape of the rear tunnel constituent portion. Further, as a modification of the embodiment, the rear tunnel constituent portion may be set such that the number of internal corners of the semipolygonal shape of the section thereof perpendicular to the extending direction of the tunnel portion is three, four, or the like number except two and is set to the number less than the number of internal corners of the semipolygonal shape of the front tunnel constituent portion.

Note that the “semipolygonal shape” as described in claim1indicates a shape in which a polygonal shape surrounded by three or more line segments is divided in two, and the semipolygonal shape is not limited to the example in the above embodiment.

Further, as a modification of the embodiment, the front tunnel constituent portion and the rear tunnel constituent portion may be configured such that their sectional shapes perpendicular to the extending direction of the tunnel portion are set to be bilaterally asymmetrical.

Further, in the above embodiment, the engine compartment14in which the engine unit16is provided is disposed in the vehicle-body front portion12. However, the vehicle lower structure10of the above embodiment may be applied to an automobile in which a power unit chamber including an engine and an electric motor (power unit) is disposed in a vehicle-body front portion.

Note that the above embodiments and the plurality of modifications described above can be combined appropriately to perform the present invention.

The embodiment of the present invention has been described above, but the present invention is not limited to the above and may be modified in various ways to be performed as long as the modifications are not beyond the gist thereof.