Lower structure of vehicle

A suspension member is mounted on the side members of an underbody. On the rear portion of the suspension member, spacers are provided between the suspension member and the underbody. Each spacer includes a bracket. The front end surface of the bracket is opposed to the rear wall surface of a main suspension body. During a frontal collision, the rear wall surface of the suspension member abuts against the bracket, whereby retreat of the suspension member is reduced.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2018-133016 filed on Jul. 13, 2018 which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract.

TECHNICAL FIELD

The present disclosure relates to the lower structure of a vehicle, and in particular, to control of the distance between components during a collision.

BACKGROUND

The lower structure of a vehicle includes an underbody and a suspension member mounted on the underbody, for operably supporting movable components of a suspension. Patent Document 1 below describes a suspension member (35) securely mounded on a front-side member (1). The rear end portion of the suspension member (35) is fixed to the front-side member (1) at a rear connection portion (37) via a separate component. Patent Document 1 also describes that an under-floor unit component (17) including a fuel cell stack (13) is mounted under the floor of the vehicle. Note that the reference numerals in the parentheses, or ( ), above are those used in Patent Document 1 mentioned below and are not related to the reference numerals used in the description of the embodiments of this specification.

CITATION LIST

Patent Literature

SUMMARY

During a frontal collision, such as a full-on or offset frontal collision, a front suspension member moves rearward relative to the underbody. There is room for improvement in reducing rearward movement of the front suspension member.

The present disclosure aims to reduce retreat, or a rearward movement, of a front suspension member relative to an underbody during a frontal collision.

According to one aspect of the present disclosure, there is provided a lower structure of a vehicle including an underbody including a framework member extending in the longitudinal direction of the vehicle; a front suspension member positioned below the front portion of the underbody and mounted on the framework member of the underbody; and a spacer provided between the underbody and the front suspension member. The spacer has a front end surface opposed to the rear wall surface of the front suspension member. During a frontal collision, the rear wall surface of the front suspension member abuts against the front end surface.

The spacer reduces retreat of the front suspension member during a frontal collision.

In one embodiment of the present disclosure, the spacer may have at least one bolt hole for penetration of a bolt for fixing the spacer to the framework member. The spacer may include an extending portion that extends forward of the vehicle from a portion where a bolt hole positioned foremost in the vehicle is defined. The front end surface of the extending portion is the front end surface of the spacer mentioned above that abuts against the rear wall surface of the front suspension member.

Provision of the extending portion enables determination of a position where the spacer abuts against the front suspension free from restriction imposed by the position where the spacer is fixed with a bolt.

In one embodiment of the present disclosure, the front suspension member may include tongue-like rear mounts extending rearward from the lower portion of the rear wall surface of the front suspension member and connected to the respective spacers. Each rear mount may have a weak structure between the portion connected to the spacer and the rear end surface.

When a collision force is applied to the front suspension member from the forward direction of the front suspension member, the rear mount having a weak structure will bend. This reduces the collision force to be transmitted to the spacer, and thus reduces retreat of the front suspension member and also retreat of the spacer.

In one embodiment of the present disclosure, the lower structure may include a battery mounted below the underbody and behind the front suspension member, the battery being for storing power for driving the vehicle. Since the spacer reduces retreat of the front suspension member during a frontal collision, the battery and the front suspension member can be kept spaced apart from each other.

In one embodiment of the present disclosure, a power line may be disposed between the front suspension member and the battery, the power line being connected to the battery. During a frontal collision, the spacer reduces retreat of the front suspension member whereby reducing the likelihood of the front suspension member to approach the power line.

DESCRIPTION OF EMBODIMENTS

Embodiments of this disclosure will now be described by reference to the drawings. In the description below, terms indicating directions or orientations, such as front, forward, back, backward, left, right, side or lateral, up or above, upward, down, and downward, indicate those relative to a vehicle unless otherwise stated. The direction extending in the front-back direction of a vehicle will be referred to as a longitudinal direction, and the direction extending in the right and left direction is referred to as a lateral direction. In the respective drawings, an arrow FR indicates the forward direction; an arrow UP indicates the upward direction; and an arrow LH indicates the leftward direction.

FIG. 1is a schematic view of a lower structure10of a vehicle; more particularly, a major part of the front portion of the lower structure10viewed upward from below. The lower structure10includes an underbody12and a front suspension member14(hereinafter referred to as a suspension member14) positioned below the front portion of the underbody12. The underbody12includes a floor16of a cabin, a dash panel18that defines the front end of the cabin, and a pair of right and left side members20extending in the longitudinal direction below the floor16and further in the forward direction. The dash panel18makes a partition for separating the cabin and a motor compartment positioned ahead of the cabin, for storing a motor, such as an electric motor. The right and left side members20bend inward below the floor16such that the respective front ends approach each other with the interval between right and left side members20becoming shorter as getting forward. A portion of each side member20more forward than the remaining portion below the floor16extends while curving upward along the dash panel18towards the forward end until a predetermined height where the portion then extends forward substantially horizontally inside the motor compartment. The pair of side members20function as framework members extending in the longitudinal direction on the respective right and left sides of the underbody12. The suspension member14is made from a sheet metal by combining and attaching a plurality of parts formed in predetermined shapes. The suspension member14may be made from a different material using a different manufacturing method. For example, extruded or cast aluminum may be used.

The suspension member14is mounted on the side members20, and constitutes a support point on the vehicle body side for movable parts of the suspension, such as lower arms. The suspension member14has a main suspension body22. Support points for movable parts of the suspension are defined on the respective right and left end portions of the main suspension body22. Mount arms24are disposed on the respective right and left sides of the front portion of the main suspension body22. The respective upper ends of the mount arms24are connected to the side members20in the motor compartment. Further, tongue-like rear mounts26extending rearward are formed on the respective right and left sides of the rear portion of the main suspension body22. The respective rear mounts26are connected to the side members20below the floor16. Between the rear mounts26and the underbody12, more particularly, the side members20, spacers28are provided. Changing the dimensions of the mount arms24and the spacers28in the up-down direction enables changing the position of the suspension member14relative to the underbody12in the up-down direction.

A battery30is mounted below the floor16. The battery30is supported from below by a gridded support frame32fixed to the right and left side members20. The support frame32has a plurality of support beams34that extend in the lateral direction and whose ends are connected to the respective right and left side members20. The battery30is fixed to the support beams34. On the front end surface of the battery30, a receptacle for connecting a power line36and a signal line38is mounted. The power line36supplies power stored in the battery30to a motor for driving a vehicle, and supplies power generated by a motor through regenerative braking to the battery30. The signal line38sends detection signals indicating parameters on the conditions of the battery30, such as the current, voltage, temperature, or the like, of the battery30.

FIG. 2is a perspective view of the suspension member14with the spacers28mounted thereon. The main suspension body22has a rear wall surface22afacing substantially rearward. The rear wall surface22ais curved in the lateral direction. The curved rear wall surface22ais disposed with the middle portion thereof positioned forward and both the end portions thereof rearward. The respective rear mounts26extend rearward from the lower portions of the both end portions of the rear wall surface22a. The dimension (thickness) of each rear mount26in the up-down direction is shorter, as compared with the thickness of the main suspension body22. On the upper surface of each rear mount26, the spacer28is attached, for example, through welding. The suspension member14is mounted on the underbody12with the respective mount arms24connected to the side members20in the front portion of the suspension member14and the respective rear mounts26and the spacers28connected to the side members20in the rear portion of the suspension member14. Each rear mount26is secured to the side member20with a bolt42, which penetrates the rear mount26and the spacer28, and with a bolt44, which penetrates the spacer28. The front-side bolt42, together with the side member20, sandwiches the rear mount26and a collar48to be described later.

FIG. 3toFIG. 5illustrate the spacer28.FIG. 3is a perspective view;FIG. 4is a side view; andFIG. 5is a cross-sectional view along the line A-A inFIG. 4. The spacer28includes a bracket46extending in the longitudinal direction, and the collar48penetrating the bracket46in the up-down direction. The bracket46has an upside-down U-shaped cross section orthogonal to the longitudinal direction, and is made from a sheet metal. The bracket46is not limited to be made from a sheet metal. For example, extruded or cast aluminum may be used. At a position more forward than the middle of the bracket46, the collar48penetrates the bracket46in the up-down direction. The portion of the bracket46penetrated by the collar48will be referred to as a penetrated collar portion46a. The bracket46has an extending portion46bthat extends forward from the penetrated collar portion46a. The collar48is a part subjected to the tightening force of the bolt42. The portion of the bracket46extending more forward than the portion subjected to the tightening force corresponds to the extending portion46b. The bracket46extends also rearward from the penetrated collar portion46a. A through hole is formed on the rear end portion46cof the rearwardly extending portion. The throughout hole corresponds to a rear bolt hole28aof the spacer28through which the bolt44is to penetrate.

A front end surface46fof the bracket46(the front end surface of the extending portion46b) is opposed to the rear wall surface22aof the main suspension body22(refer toFIG. 2andFIG. 6). The bracket46is a part of the spacer28, and the front end surface46fof the bracket46is also the front end surface of the spacer28.

The collar48has a column shape, whose upper end surface48ais positioned at the same height as the upper surface46dof the rear end portion46cof the bracket, and whose lower end surface48bis positioned at the same height as the lower edge46eof the penetrated collar portion46aof the bracket. The collar48is attached to the bracket46through welding, for example. Specifically, the side surface of the collar48is welded to the upper surface of the penetrated collar portion46aof the bracket. The collar48constitutes the front bolt hole28bof the spacer, through which the bolt42is to penetrate. The upper end surface48aand the upper surface46dof the rear end portion46cof the bracket may have different heights to fit the shape of the surface to which the spacer28is attached.

The spacer28is attached by welding the lower edge46eof the penetrated collar portion46aof the bracket to the rear mount26of the suspension member14. Meanwhile, the lower edge46gof the extending portion46bis not welded to the rear mount26.

A corner46hdefined by the front end surface46fand the lower edge46gof the bracket46is chamfered; in particular, round-chamfered. The front end surface46fof the bracket has an upside-down U-shape, with the corner46hof the lower end portion of each of the two parallel portions of the U-shaped portion being round-chamfered.

FIG. 6andFIG. 7are schematic side views of a structure of the suspension member14; in particular, around the rear mount26. In particular,FIG. 6illustrates the positional relationship between the suspension member14and the spacer28; andFIG. 7illustrates the positional relationship between the suspension member14and the power line36. InFIG. 7, the inside structure of the main suspension body22is not illustrated.

As well illustrated inFIG. 6, the thickness of the rear mount26is smaller, as compared with that of the main suspension body22, and the thickness of the suspension member14becomes suddenly and remarkably reduced toward the rearward direction in an area near the rear wall surface22a. As well illustrated inFIG. 2, in the lateral direction as well, the lateral dimension (width) of the rear mount26is smaller, as compared with the main suspension body22, and becomes remarkably and suddenly reduced. Such a portion whose thickness reduces suddenly and remarkably is weak and thus will start deforming earlier than other portions upon receipt of a force during a collision. That is, the root of the rear mount26and its surrounding portion are weak portions that will start deforming earlier than other portions.

The spacer28is provided between the suspension member14and the side member20, and defines the position of the suspension member14in the up-down direction relative to the underbody12. The position of the suspension member14in the up-down direction can be changed depending on whether the spacer28is present or by changing the thickness of the spacer28. The spacer28is fixed to the side member20at two points in the longitudinal direction. Specifically, the spacer28is attached to the side member20together with the suspension member14with the bolt42on the front side, and also to the side member20with the bolt44on the rear side. The extending portion46bof the bracket of the spacer28extends forward from the position where the spacer28is fixed with the bolt42such that the front end surface46fof the extending portion46bis opposed to the rear wall surface22aof the suspension member14. The extending portion46bof the bracket will abut against the rear wall surface22aof the suspension member14, which will retreat, or move backward, during a full-on frontal collision or an offset frontal collision. Changing the length of the extending portion46benables changing the position where the extending portion46babuts against the suspension member14. This enables controlling the amount of retreat of the suspension member14.

Since the rear wall surface22aof the main suspension body22is curved, a portion of the rear wall surface22aopposed to the power line36is positioned more forward than a portion of the rear wall surface22aopposed to the spacer28, as illustrated inFIG. 7.

FIG. 8illustrates the lower structure10that is deforming during a frontal collision under a predetermined condition. Assume that the condition at a frontal collision can be, for example, the same as the condition in a predetermined full-on frontal collision test or offset frontal collision test. For example, in a full-on frontal collision test, a vehicle is brought into frontal collision against a wall surface at the speed of 55 km/h. In an offset frontal collision, a vehicle is brought into collision against an object having a predetermined structure with the overlap rate of 40% at 64 km/h.

While the cabin of a vehicle has a rigid structure to protect an occupant, the portion more forward than the cabin has a structure that is relatively readily deformable in order to absorb the energy during a collision. When the lower structure10receives a collision force F during a frontal collision, the front portion of the lower structure10deforms. Accordingly, the suspension member14retreats. Meanwhile, since the spacer28is fixed to a rigid portion under the floor of the side member20, the rear mounts26of the suspension member14will not be largely displaced. Consequently, the weak portion of the rear mounts26will bend. As illustrated inFIG. 8, the rear mount26bends into a V-shape, upon which the rear wall surface22aof the main suspension body is caused to abut against the front end surface46fof the bracket. With the above, retreat of the suspension member14is reduced. Consequently, deformation of the underbody12, such as the floor16, caused by the suspension member14can be reduced. Further, as the retreat of the suspension member14is reduced, the likelihood of the suspension member14to crash into the battery30can be reduced. Also, it is possible to reduce the likelihood of the power line36to be inserted into the space between the suspension member14and the underbody12.

Desirable setting of the length of the extending portion46bof the bracket enables controlling the position where the suspension member14will abut against the bracket46and the retreat amount of the suspension member14.

During a frontal collision, since the rear mount26deforms at earlier timing, the likelihood of the deformation or removal of the spacer28earlier than the rear mount26can be reduced. This can enhance the reliability in receiving the retreating suspension member14. Since the extending portion46bof the bracket is not attached to the rear mounts26, the rear mount26can freely bend into a V-shape. Further, the extending portion46bdoes not receive a force due to deformation of the rear mounts26. This makes it possible to reduce deformation of the extending portion46b, so that the extending portion46bcan be held opposed to the rear wall surface22aof the main suspension body.

Chamfering a part of the peripheral edge of the front end surface46fof the bracket enables reducing the likelihood of the bracket46to stick into the rear wall surface22aof the main suspension body. If the bracket46sticks, the bracket46will not be able to sufficiently support the retreating suspension member14, thereby weakening the effect of reducing the retreating movement. As the front end surface46fis chamfered, the likelihood of the bracket46to stick into the rear wall surface22acan be reduced, and the retreat of the suspension member14can be efficiently reduced. Further, if the bracket46sticks into the rear wall surface22a, the suspension member14will be blocked from moving downward. Consequently, the collision force will not be released, so as not to be transmitted to the underbody12. Chamfering the front end surface46fenables releasing the collision force, so that the collision force will not be transmitted to the underbody12and the battery30.

The structure of the spacer is not limited to a structure constituted of two components; namely, the bracket46and the collar48, but can be made from a single component. The shape of the front end surface of the spacer is not limited to a U-shape, but can be, for example, a solid quadrilateral or a quadrilateral frame shape. The whole peripheral edge of the front end surface may be chamfered, or only a part of the peripheral edge may be chamfered. Alternatively, only a corner may be chamfered.

Another aspect of the present disclosure will be described below.

(1) A lower structure of a vehicle includes an underbody including a framework member extending in the longitudinal direction of the vehicle; a front suspension member positioned below the front portion of the underbody and mounted on the framework member of the underbody; and a spacer provided between the underbody and the front suspension member and having at least one bolt hole for penetration of a bolt for fixing to the framework member. The spacer includes an extending portion extending forward of the vehicle from a portion where a foremost bolt hole in the vehicle is defined. The front end surface of the extending portion is opposed to the rear wall surface of the front suspension member.

REFERENCE SIGNS LIST