Front vehicle body structure

A front vehicle body structure has a member provided at a side section of a vehicle body along a vehicle-body front-rear direction, a powertrain disposed on an inner side of the vehicle body relative to the member and fixed to a front section of the vehicle body, and a load transmission member provided on the member and configured to come into contact with one end portion, in a vehicle width direction, of the powertrain when receiving a collision load applied by an obstacle from a front side of the vehicle body, and to transmit the load from the obstacle to the powertrain in a state of being sandwiched between the obstacle and the powertrain. The load transmission member has a concave curved surface formed in a surface thereof along the vehicle-body front-rear direction. The concave curved surface is elastically deformed in the state of being sandwiched between the obstacle and the powertrain and receiving the load.

BACKGROUND

1. Technical Field

The present invention relates to a front vehicle body structure.

2. Related Art

A technique described in Japanese Patent Unexamined Publication No. 2008-213739 has heretofore been known as a measure for small overlap collision. The small overlap collision refers to a collision in which an obstacle collides with a vehicle body from the front side of the vehicle body at a position outward, in the vehicle width direction, from a side member provided at a side section of the vehicle body along the front-rear direction.

In the technique described in Japanese Patent Unexamined Publication No. 2008-213739, a bumper reinforcement is provided at the front end of the side member, the bumper reinforcement being provided along the vehicle width direction. Further, a reinforcement extension is provided to extend rearward from an outer end portion of the bumper reinforcement in the vehicle width direction. The reinforcement extension includes a protruding section formed to protrude toward the side member. At the time of the small overlap collision, the protruding section comes into contact with the side member to exert a resistive force. Moreover, at the moment of the contact, the protruding section is received by a stopper bracket provided on the side member so that the side member can be prevented from being displaced rearward.

SUMMARY

Meanwhile, the conventional front vehicle body structure may undergo, for example, full overlap collision or the like in which a collision load is exerted on each side member from the front side of the vehicle body. In this case, the reinforcement extension, which is disposed along the side member, interferes and makes it difficult for the side member to be crushed. Consequently, the amount of deformation of the side member is reduced, and the impact absorption performance may possibly be lowered.

A front vehicle body structure according to one or more embodiments of the present invention has enhanced performance of absorbing collision load from the front side of the vehicle.

A front vehicle body structure according to one or more embodiments of the present invention includes: a member provided at a side section of a vehicle body along a vehicle-body front-rear direction; and a powertrain disposed on an inner side of the vehicle body relative to the member. The front vehicle body structure further includes a load transmission member provided on the member and configured to come into contact with one end portion, in a vehicle width direction, of the powertrain when receiving a collision load applied by an obstacle from a front side of the vehicle body, and to transmit the collision load to the powertrain in a state of being sandwiched between the obstacle and the powertrain.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described in detail with reference to the drawings. In embodiments of the invention, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid obscuring the invention. Note that the dimensional proportions in the drawings may be exaggerated for convenience and may differ from the actual proportions.

First Embodiment

FIG. 1shows a front vehicle body structure according to a first embodiment of the present invention.FIG. 1shows the initial state of collision of a left front section of a vehicle body1with an obstacle3. Note that in the drawings, the direction shown by arrow FR is the front side of the vehicle body and the direction shown by arrow LH is the left side of the vehicle body.

A pair of front side members5as side members is provided along the vehicle-body front-rear direction (left-right direction inFIG. 1) at the opposite sections of the vehicle body1in the vehicle width direction. As shown inFIGS. 2 and 3, at a lower portion of each front side member5around the front side of the vehicle body, the upper end of a coupling member7provided along the vertical direction (the direction perpendicular to the plane of the sheet ofFIG. 2) is coupled. Further, the lower end of the coupling member7is coupled to an upper portion of a load transmission member9. Also, the load transmission member9is coupled to an end portion, in the vehicle width direction, of a cross member11provided along the vehicle width direction. Details of the shape of the load transmission member9will be described later.

As shown inFIG. 1, a dash panel13is disposed on the rear side of the vehicle body relative to the cross member11. Relative to the dash panel13, an engine compartment15is formed on the front side of the vehicle body and a cabin17is formed on the rear side of the vehicle body. The cabin17includes a floor panel19at the bottom. At the center of the floor panel19in the vehicle width direction, a center tunnel section21is formed which is provided along the vehicle-body front-rear direction and protrudes toward the upper side of the vehicle body (toward the front surface of the sheet ofFIG. 1).

The engine compartment15is an area surrounded by the left and right front side members5, the cross member11, and the dash panel13, and a powertrain23which includes an engine and a transmission is disposed in this area. Moreover, the powertrain23is mounted to the left and right front side members5through mount brackets not shown.

A hood ridge panel25is provided outward, in the vehicle width direction, from each front side member5in the engine compartment15. Moreover, a strut tower27is provided inward from the hood ridge panel25in the vehicle width direction near the dash panel13. A hood ridge lower front section28is formed on a front lower side of the strut tower27. Also, a front pillar29is located on the rear side of the vehicle relative to the hood ridge panel25. Further, the front end of a side sill31which is provided along the vehicle-body front-rear direction is coupled to the lower end of the front pillar29.

As shown inFIG. 3, the load transmission member9includes: a base section9awhich has a flat and substantially cuboidal shape and a protruding section9bwhich has a long and substantially cuboidal shape and protrudes upward from the top of the base section9a. Here, as for the load transmission member9inFIG. 3, its longitudinal direction in a plan view seen in the vertical direction of the vehicle body will be referred to as the X direction, and a direction perpendicular to the X direction will be referred to as the Y direction.

The protruding section9bis provided along the X direction substantially on the center of the base section9ain the Y direction. A front end surface9a1of the base section9aon the front side of the vehicle body is such that its inner side in the vehicle width direction is bent at a bent portion9a2toward the rear side of the vehicle body, thereby forming a bent surface9a11. Also, the bent portion9a2is located to substantially coincide with the inner edge of the protruding section9bin the vehicle width direction. As a result, the front end surface9a1is in a shape protruding toward the front side of the vehicle body. Likewise, as shown inFIG. 1, a rear end surface9a3of the base section9aon the rear side of the vehicle body is such that its inner side in the vehicle width direction is bent at a bent portion9a4toward the rear side of the vehicle body. Also, the bent portion9a4is located to coincide with the inner edge of the protruding section9bin the vehicle width direction. As a result, the rear end surface9a3is in a shape recessed toward the front side of the vehicle body.

As shown inFIGS. 2 and 3, an upper surface9b1of the protruding section9bis formed as a concave curved surface, and a side surface9b2of the protruding section9bon the outer side in the vehicle width direction is also formed as a concave curved surface. Moreover, an upper surface9a5of the base section9alocated on the outer side in the vehicle width direction is also formed as an concave curved surface like the upper surface9b1of the protruding section9b. In sum, in the first embodiment, concave curved surfaces are formed in the surface of the load transmission member9along the vehicle-body front-rear direction.

As shown inFIG. 1, while attached to the front side member5and the coupling member7, this load transmission member9as a whole is such that a section thereof on the front side of the vehicle body is located outward from a section thereof on the rear side of the vehicle body in the vehicle width direction. In order words, the load transmission member9is inclined in the vehicle-body left-right direction with respect to the vehicle-body front-rear direction.

Here, while the load transmission member9is attached to the vehicle body1, a side surface9a6of the base section9aon the inner side in the vehicle width direction, on the front side of the vehicle body, is in contact with and fixed to an end portion in the vehicle width direction11aof the cross member11through an attachment33. On the other hand, the lower end of the coupling member7shown inFIGS. 2 and 3is fixed substantially to the center, in the X direction, of the upper surface9a5of the base section9aon the outer side in the vehicle width direction. Thus, the load transmission member9is provided between the front side member5and the cross member11.

Moreover, as shown inFIG. 1, the rear end surface9a3of the base section9aand a rear end surface9b3of the protruding section9bon the rear side of the vehicle body face a corner portion23aof the powertrain23located at a front section thereof on the outer side in the vehicle width direction. Also, while the load transmission member9is attached as described above, the rear end surface9a3and the rear end surface9b3are spaced away from the corner portion23aby a certain distance.

Description will now be given of the path of transmission of a collision load applied when a vehicle including the above-described front vehicle body structure collides from the front side with the obstacle3such as another automobile, as shown inFIG. 1. Note that the collision here is assumed to be collision of the obstacle3with a spot around the front side member5on the left side in the vehicle width direction. This collision with the spot around the front side member5includes small overlap collision in which the obstacle collides at a position outward from the front side member5in the vehicle width direction.

In the small overlap collision, when the obstacle3reaches the load transmission member9through a front bumper35shown inFIG. 4, the load transmission member9is moved toward the rear side of the vehicle body along with the cross member11and the coupling member7, which are attached to the load transmission member9. By this movement, the rear end surfaces9a3,9b3on the rear side of the load transmission member9come into contact with the corner portion23aof the powertrain23, which is located at the front section thereof on the outer side in the vehicle width direction, and thereby transmit the collision load thereto. The direction of this load transmission is the direction of arrow F inFIG. 1which corresponds to the longitudinal direction of the load transmission member9. Here, the front side member5is formed to be more fragile at a section thereof on the front side of the vehicle body relative to the coupling member7than a section thereof on the rear side of the vehicle relative to the coupling member7. Hence, the fragile front section is crushed.

Moreover, since the direction of the load transmission is the direction of arrow F during the above-mentioned movement, the load transmission member9and the powertrain23turn counterclockwise inFIGS. 1 and 4with the load transmission member9sandwiched between the obstacle3and the powertrain23. Here, the load transmission member9and the powertrain23turn while maintaining substantially the same relative positions with each other. Note that the upper surface9b1and the side surface9b2on the outer side in the vehicle width direction of the protruding section9bof the load transmission member9as well as the upper surface9a5of the load transmission member9are formed as concave curved surfaces. Thus, when the load is transmitted, these curved surfaces are elastically deformed to be curved further, which reduces the likelihood of fracture of the load transmission member9. Hence, the load transmission can be done efficiently.

As shown inFIG. 4, the powertrain23, which turns as described above, turns counterclockwise about a fulcrum around a portion thereof mounted to the front side member5at an end portion on the right side in the vehicle width direction (upper side inFIG. 4). In this turn, the powertrain23transmits the load thereto such that a rear portion23bon the left side in the vehicle width direction comes into contact with around the center tunnel section21of the floor panel19. A stiffness of the center tunnel section21is higher than other flat portions of the floor panel19on which the occupants place their feet. Thus, the turn of the powertrain23can be stopped by the center tunnel section21at an earlier stage and the deformation of the cabin17can therefore be reduced to be smaller. Note that a section of the cabin17located on the lower side of the vehicle body relative to the dash panel13shown inFIG. 1is shown, and the dash panel13is therefore not shown inFIG. 4.

Moreover, using the inertia force of the powertrain23generated by its turn, the whole vehicle body moves laterally toward the right side in the vehicle width direction (upper side inFIG. 4) so as to bring the obstacle3away from the front pillar29. As a result, the deformation of the cabin17by the obstacle3is reduced. Meanwhile, broken line P inFIG. 1is the trajectory of the obstacle3after the collision. As the vehicle body1(front pillar29) moves laterally toward the upper side inFIG. 4, the obstacle3moves in the direction opposite to this lateral movement, which is toward the lower side inFIG. 4. By the above-described features, the front vehicle body structure of the first embodiment can achieve enhanced performance of absorbing collision load from the front side of the vehicle.

As mentioned above, the load transmission member9is disposed between the front side member5and the cross member11. Moreover, the end portion of the load transmission member9on the rear side of the vehicle body protrudes only slightly into the engine compartment15. Hence, flexibility is ensured for the layout of components inside the engine compartment15.

Also, in the first embodiment, the load transmission member9is elastically deformed in the state of being sandwiched between the obstacle3and the powertrain23and receiving a load, which reduces the likelihood of fracture of the load transmission member9. Hence, the load transmission to the powertrain23can be done efficiently.

Here, in the first embodiment, the load transmission member9has concave curved surfaces formed in the surface (the upper surface9b1, the side surface9b2, and the upper surface9a5) thereof along the vehicle-body front-rear direction. Also, the concave curved surfaces are elastically deformed to be curved further in the state of receiving the load, which further reduces the likelihood of fracture of the load transmission member9. Hence, the load transmission to the powertrain23can be done more efficiently.

Note that the shape of the rear end surfaces9a3,9b3, which are the portions of the load transmission member9at which it comes into contact with the powertrain23, is one important feature for the load transmission member9to remain sandwiched between the powertrain23and the obstacle3after coming into contact with the powertrain23.

For this reason, in the first embodiment, the rear end surface9a3is bent at the bent portion9a4to have a shape recessed toward the front side of the vehicle body. In this way, this recessed portion can receive the corner portion23aof the powertrain23and ensure the load transmission member9to remain sandwiched between the powertrain23and the obstacle3. In this case, the shape of the rear end surfaces9a3,9b3of the load transmission member9is designed in conformity with the shape of the corner portion23a, which is the portion of the powertrain23where it comes into contact with the load transmission member9. With this shape, the load transmission member9can remain sandwiched between the powertrain23and the obstacle3.

Alternatively, a shape as shown inFIG. 5may be employed as another example. Specifically, the rear end surface9a3of a load transmission member9A on the side where it comes into contact with the powertrain23may have a shape that accommodates the difference in strength (material) between an upper section23U and a lower section23L of a housing of the powertrain23.

In this case, as shown inFIG. 5, the housing of the powertrain23includes the upper section23U made of an aluminum alloy and the lower section23L serving as an oil pan made of iron higher in stiffness than the upper section23U. Here, when the load transmission member9comes into contact with the powertrain23as shown inFIG. 4, the upper section23U and the lower section23L are located to coincide with the protruding section9band the base section9a, respectively.

Also, a recessed section9cto enter for the lower section23L with higher stiffness is provided in the rear end surface9a3of the base section9awhich is located to coincide with the lower section23L. The recessed section9cis formed at a position which is substantially at the center in the Y direction and substantially under the protruding section9b. When the load transmission member9comes into contact with the powertrain23as shown inFIG. 4, the upper section23U with lower rigidity is crushed rearward to the position of a two-dot chain line shown inFIG. 5whereas the lower section23L with higher rigidity enters the recessed section9cof the load transmission member9since it is harder to crush. Note that the load transmission member9is made of iron like the lower section23L.

In this way, it is easier for the load transmission member9to remain sandwiched between the obstacle3and the powertrain23after coming into contact with the powertrain23. Hence, the load transmission by the following turning movement can be done efficiently.

UsingFIGS. 6 to 8, description will now be given of full overlap collision in which substantially the entire area of the vehicle body1in the vehicle width direction collides with an obstacle3A such as another automobile, or moderate overlap collision in which the obstacle3A collides at a position that covers at least one of the left and right front side members5.

In this case, the obstacle3A comes into contact with the load transmission member9at a contact portion Q through the front bumper not shown. This contact portion Q corresponds to the bent surface9a11located inward from the bent portion9a2in the vehicle width direction. Further, the contact portion Q is located outward, in the vehicle width direction, from the corner portion23aof the powertrain23, at which it comes into contact with the load transmission member9. In other words, in the first embodiment, the contact portion Q of the load transmission member9on the front side of the vehicle body which comes into contact with the obstacle3A is located outward, in the vehicle width direction, from a contact portion R of the load transmission member9on the rear side of the vehicle body which comes into contact with the powertrain23. Also, the direction of the load transmission during the contact mentioned above is the direction of arrow F which is substantially in parallel with the vehicle-body front-rear direction.

For this reason, after coming into contact at the contact portion Q with the powertrain23as shown inFIG. 6, the load transmission member9comes into contact at the rear end surface9a3with the corner portion23aof the powertrain23as shown inFIG. 7. Then, the whole powertrain23turns counterclockwise inFIG. 7about the contact portion R. Thereafter, as shown inFIG. 8, the load transmission member9moves such that the X direction (longitudinal direction) is substantially in parallel with the vehicle width direction with the front end surface9a1located on the outer side in the vehicle width direction and the rear end surface9a3located on the inner side in the vehicle width direction. In this case, the load transmission member9starts turning at an earlier stage than it does in the small overlap collision inFIGS. 1 and 4, so that the load transmission from the load transmission member9to the powertrain23is stopped at an earlier stage. Hence, the deformation of the cabin17by the powertrain23can be reduced.

Also, in this case, since the load transmission member9starts turning at an earlier stage as mentioned above, it is accordingly easier for the front side member5to be crushed. As a result, the front side member5is deformed by a sufficient amount. Hence, the impact absorption performance can be enhanced.

As described above, the front vehicle body structure according to the first embodiment includes: a member provided at the side section of the vehicle body along the vehicle-body front-rear direction; and the powertrain23disposed on the inner side of the vehicle body relative to the member and fixed to the front section of the vehicle body. The front vehicle body structure further includes the load transmission member provided on the member and configured to come into contact with one end portion, in the vehicle width direction, of the powertrain when receiving a collision load applied by an obstacle from the front side of the vehicle body, and to transmit the load to the powertrain in the state of being sandwiched between the obstacle and the powertrain.

Also, the front vehicle body structure according to the first embodiment further includes the cross member11provided along the vehicle width direction. Moreover, in the first embodiment, the member is a pair of left and right side members provided at the respective side sections of the vehicle body along the vehicle-body front-rear direction, and the cross member11couples the pair of left and right side members to each other. Furthermore, the load transmission member9is provided between each of the side members and the cross member and transmits the collision load to the powertrain23while turning along with the powertrain in the state of being sandwiched between the obstacle3and the powertrain. In this way, the collision load received by the load transmission member is efficiently transmitted to the vehicle body through the powertrain. Hence, the performance of absorbing collision load from the front side of the vehicle body can be enhanced.

While a first embodiment is described above as an example, the present invention is not limited to the first embodiment. For example, the load transmission member9is coupled to the end portion11aof the cross member11in the vehicle width direction in the first embodiment, but the load transmission member9can be coupled to the upper surface of the cross member11. In other words, in this case, the load transmission member9is coupled to the cross member11and the coupling member7in such a way as to be sandwiched between the cross member11on the lower side and the coupling member7on the upper side. Such a coupled state can also achieve similar advantageous effects. Note that although the left side of the vehicle body is described in the first embodiment, the load transmission member is also provided similarly on the right side of the vehicle body.

Second Embodiment

A front vehicle body structure according to a second embodiment of the present invention will be described with reference toFIGS. 9 to 25. Note that in the drawings, the direction shown by arrow FR is the front side of the vehicle body and the direction shown by arrow RR is the rear side of the vehicle body. Also, the direction shown by arrow RH is the right side of the vehicle body and the direction shown by arrow LH is the left side of the vehicle body.

First, a front vehicle body structure MK will be described with reference toFIGS. 9 and 10.FIG. 9is a perspective view of a front section of a vehicle body M as seen diagonally from a left front upper side for explaining the front vehicle body structure MK. Some members are omitted to facilitate the understanding.FIG. 10is a bottom view of the front section of the vehicle body M for explaining the front vehicle body structure MK.

A pair of front side members101L,101R are provided on the opposite sides of the front section of the vehicle body M in the vehicle width direction, the pair of front side members101L,101R being provided along the vehicle-body front-rear direction. Hereinafter, the pair of left and right front side members will also be referred to simply together as the front side members101.

The space between the pair of front side members101L,101R in the front section part of the vehicle body M is an engine compartment RM1. Inside the engine compartment RM1, a powertrain102is disposed and supported at the opposite sides in the width direction on the front side members101L,101R. The powertrain102includes an engine disposed on the right side of the vehicle body M and a transmission102B disposed on the left side of the vehicle body M. Support positions102SL,102SR of the powertrain102on the front side members101L,101R are shown by dashed lines inFIG. 9and by + symbols inFIG. 10.

A dash panel103is disposed behind the engine compartment RM1, and a cabin RM2is provided behind the dash panel103.

A suspension member104is provided below the front side members101L,101R. The suspension member104is formed in such a way as to couple a pair of left and right side sills109L,109R to each other and to surround the left, right, and rear sides of the powertrain102. The suspension member104includes: a side extension member104L provided on the left side of the vehicle body M along the vehicle-body front-rear direction; and a side extension member104R provided on the right side of the vehicle body M along the vehicle-body front-rear direction. The suspension member104further includes a coupling part104M coupling the rear end sides of the side extension members104L,104R to each other. The side extension member104L is formed by: a base member104La on the rear side; and an add-on member104Lb coupled to the front end of the base member104La through a coupling portion P1and extending forward therefrom.

The front side members101and the side extension members104L,104R of the suspension member104form a side member assembly KG. The pair of left and right side extension members104L,104R are disposed to sandwich the powertrain102therebetween.

Front end portions of the side extension members104L,104R of the suspension member104and front end portions of the front side members101L,101R are coupled respectively by strut parts105L,105R extending in the vertical direction of the vehicle body M. The front end portions of the side extension members104L,104R of the suspension member104are coupled to each other by a lower support (cross member)106configured to support a radiator core not shown.

Load transmission members107L,107R are attached to the side extension members104L,104R of the suspension member104behind the portions thereof where the strut parts105L,105R are coupled. Hereinafter, the load transmission members107L,107R will also be referred to simply together as the load transmission member107. Meanwhile, front wheels M1and a front bumper M2are also shown inFIG. 10.

The load transmission member107L and the load transmission member107R are formed substantially plane-symmetrical with each other. For this reason, the structure of the load transmission member107L will be representatively described with reference toFIGS. 11 to 14.

FIG. 11is a perspective view of the load transmission member107L in substantially the same posture as that shown inFIG. 9.FIG. 12is an exploded view of the load transmission member107L.FIG. 13is a set of views of the load transmission member107L at three different angles.FIGS. 13(a), 13(b), and 13(c)are front, bottom, and right-side views, respectively, in the state of being attached to the side extension member104L.FIG. 14is a cross-sectional view taken along line S1-S1inFIG. 13(b).

The load transmission member107L includes, as exterior members, an outer side wall section107a, an inner side wall section107b, a front wall section107c, a rear wall section107d, a top plate section107e, and a bottom wall section107f. By assembling these members, a housing107gis formed which has a space SP1therein. The outer side wall section107ahas an outer surface107a1formed as a curved surface, in particular, a surface curved concavely in an arch shape in a plan view. Moreover, the outer surface107a1is formed to include an upper surface107a1a(first surface) on the upper side of the vehicle body and a lower surface107a1b(second surface) on the lower side of the vehicle body. At the center of the outer surface107a1in the vertical direction, a stepped portion107a2is provided such that the lower surface107a1bprotrudes to a position outward from the upper surface107a1aand is formed with the same curvature as the upper surface107a1a.

As shown inFIG. 12, the housing107ghouses therein an upper plate107h1, a lower plate107h2, a stay107h3, a sub plate107h4, and a pipe107h5as a structural part assembly KG2. Housing the structural part assembly KG2can improve the stiffness of the load transmission member107L. Note that inFIG. 14, positions at which welding is performed on the structural part assembly KG2are shown with ▴ symbols. The welding can be arc welding or spot welding, for example.

The upper plate107h1, the lower plate107h2, the stay107h3, and the sub plate107h4include protruding portions, bent portions, and the like along the direction in which the outer side wall section107aand the inner side wall section107bare connected (the direction of arrow DR1). The pipe107h5is formed with its axis aligned in the direction of arrow DR1. In this way, the load transmission member107L is formed to have high stiffness in the direction of arrow DR1. Hereinafter, this direction in which the outer side wall section107aand the inner side wall section107bare connected will also be referred to as the load transmission direction DR1.

The housing107gof the load transmission member107L has bolt holes at three positions for fixing the load transmission member107L to its counterpart with bolts. Specifically, there are a bolt hole107gv(seeFIG. 11andFIG. 13(b)) for fixing in the vertical direction and bolt holes107gvat two positions for fixing in the horizontal direction. The bolt holes107ghare formed in the bottom wall section107f. In the front vehicle body structure MK, the counterpart to which the load transmission member107L is fixed through the bolt holes107gv,107ghat the three positions is the side extension member104L of the suspension member104.

The state where the load transmission member107L is fixed to the side extension member104L will now be described with reference toFIG. 15. The add-on member104Lb of the side extension member104L is formed in an angular tube shape having a substantially horizontal upper surface and a substantially vertical outer side surface (seeFIG. 24). The load transmission member107L is fixed to the add-on member104Lb of the side extension member104L with bolts BT1, BT2. Specifically, from the left side of the vehicle body M, two bolts BT1are inserted into the bolt holes107ghwhich are formed in the bottom wall section107fand fastened to internally threaded portions not shown provided in the outer side surface of the add-on member104Lb. Moreover, from the upper side, a bolt BT2is inserted into the bolt hole107gvand fastened to an internally threaded portion (not shown) provided in the upper surface of the add-on member104Lb. Hereinafter, the axis of the bolt BT2will also be referred to as the fixing axis CL7.

Thus, the load transmission member107L is fastened with bolts in two axial directions, namely, the width direction and the vertical direction of the vehicle body M, and the bottom wall section107fis fixed to both the upper surface and the outer side surface of the rectangular add-on member104Lb. In this way, displacement and loosening are less likely to occur. Hence, the load transmission member107L and the add-on member104Lb are firmly fixed to each other as one member.

The load transmission member107L fixed to the suspension member104has the following features in term of shape.FIG. 16is a view of a left front section of the vehicle body M as seen from a position under the front side member101L (see arrow Y1inFIG. 9).

The load transmission member107L is fixed to the add-on member104Lb in such a posture as to project therefrom diagonally forward while extending toward the outer side of the vehicle body M, and diagonally rearward while extending toward the inner side of the vehicle body M. In other words, the housing107gis attached in such a way as to straddle the add-on member104Lb in the width direction. In such a state, an angle λa between the load transmission direction DR1and an axis CL1in the vehicle-body front-rear direction is 0°<θa<90°. The angle θa is approximately 65°, for example.

On the outer surface107a1of the outer side wall section107aof the load transmission member107L, a rear end107a3is an apex107jwhich is the portion of the load transmission member107L protruding furthest in the width direction. Also, a straight line inFIG. 16connecting a tip107a4(first position) and the apex107j(second position) will be referred to as the inclination line LN1, the tip107a4being a portion of the outer surface107a1where it joins the add-on member104Lb. Here, an angle θb as the interior angle between the inclination line LN1and the axis CL1in the vehicle-body front-rear direction is equal to or smaller than 45°. Also, the outer surface107a1is a curved surface recessed inward from the inclination line LN1in the width direction of the vehicle body M.

An outer surface107b1of the inner side wall section107bof the load transmission member107L protrudes to a position on the inner side of the vehicle body relative to the side extension member104L, and faces a left front end portion (corner portion)102Lt of the powertrain102. Further, the outer surface107b1is formed to include a bent portion107b1awhere the outer surface107bis recessed at the center. This bent portion107b1ais formed in conformity with the shape of the left front end portion102Lt of the powertrain102.

The structures and configurations of the load transmission member107L and the add-on member104Lb described above apply also to the load transmission member107R and an add-on member104Rb which are symmetrical therewith about the center axis of the vehicle body M.

Description will now be given of the transmission of a collision load and the behavior of each member in a small overlap collision at the left front section of the vehicle body M with reference toFIGS. 17 to 20(d). An obstacle ST that collides with the vehicle body M in the small overlap collision is shown, for example, inFIG. 10in contact with the front bumper M2.

InFIG. 17, in relation toFIG. 10, a state where the vehicle body M undergoes a small overlap collision with the obstacle ST as a result of moving toward the left is shown as relative movement of the obstacle ST. InFIG. 17, the front bumper M2is not shown.FIG. 17shows a state where the obstacle ST has deformed the front end portion of the front side member101L and the front end portion of the side extension member104L of the suspension member104and collided with the outer surface107a1of the load transmission member107L.FIG. 18is a schematic view for explaining a collision load F resulting from the collision of the obstacle ST with the outer surface107a1.

FIG. 19is a graph for explaining the relationship between an axial force fx and a lateral force fy derived from the collision load F, and the angle of inclination of the collided portion. First, the component of the force of the collision load F will be described with reference toFIGS. 18 and 19.

The outer surface107a1is inclined to be separated outwardly further away from the vehicle body M as extending from the front side to the rear side of the vehicle body M. For this reason, as shown inFIG. 18, assuming that the obstacle ST collides with the outer surface107a1at a collision point P2, the collision load F applied to the load transmission member107L is divided into a component f1along a tangential line LN2at the collided portion and a component f2perpendicular to the tangential line LN2. Further, the component f2is divided into the axial force fx in parallel with the axis CL1in the front-rear direction and the lateral force fy perpendicular to the axis CL1. Here, the tangential line LN2is assumed to be inclined at an angle θc with respect to the axis CL1in the front-rear direction.

The relationship in magnitude between the axial force fx and the lateral force fy is dependent on the angle θc and is shown inFIG. 19. InFIG. 19, the horizontal axis shows the angle θc (0° to 90°) while the vertical axis shows the percentage of each force such that the axial force fx is 100% when the angle θc is 90°, i.e. when the collided surface is perpendicular to the direction of the collision. As is clear from the graph, the axial force fx and the lateral force fy match each other when the angle θc is 45°. Further, the axial force fx is greater than the lateral force fy when the angle θc is within a range of from above 45° to 90°. Furthermore, the lateral force fy is greater than the axial force fx when the angle θc is within a range of from above 0° to below 45°.

The collision of the obstacle ST with the load transmission member107L in the small overlap collision will be described under assumption of the points mentioned above. The obstacle ST collides with the outer surface107a1, which is inclined with respect to the direction of the collision load F to be located further outward as extending rearward. The load transmission member107L has relatively high stiffness since it is provided with the structural part assembly KG2. It is therefore mainly the add-on member104Lb that is greatly deformed, and the load transmission member107L is moved toward a rear inner side. By this movement toward the rear inner side, the inner side wall section107bof the load transmission member107L comes into contact with the left front end portion102Lt of the powertrain102.

Having high rigidity particularly in the load transmission direction DR1, the load transmission member107L is deformed only slightly even when colliding with the powertrain102. For this reason, as shown inFIG. 17, the collision load is transmitted efficiently to the powertrain102as a force toward a right rear side (moving force F7).

The powertrain102is large in mass and therefore large in inertia force. Moreover, the moving force F7, which originates from the collision of the obstacle ST, is large enough to change the moving direction of the vehicle body M along with the powertrain102. That is, upon receipt of the moving force F7applied from the load transmission member107L to the left front end portion102Lt, the powertrain102moves toward the right side of the vehicle body M. Due to this movement, the vehicle body M changes its direction in such a way as to move away from the obstacle ST toward the right side.

With the front vehicle body structure MK, the collision load applied to the load transmission member107L in the small overlap collision is transmitted to the powertrain102at high efficiency. Such load transmission changes the moving direction of the powertrain102, which is large in mass, and also changes the moving direction of the vehicle body M.

As described above, in the front vehicle body structure MK, the load transmission member107L is attached to the side extension member104L of the suspension member104. The load transmission member107L includes the outer side wall section107awhich protrudes outward further in the width direction as extending toward the rear side of the vehicle body, and the inner side wall section107bwhich projects from the side extension member104L to a position inward from the side extension member104L in the width direction and near the powertrain102. Then, when a collision load toward the rear side of the vehicle body M is applied to the outer side wall section107a, the side extension member104L is deformed and the inner side wall section107bcomes into contact with the powertrain102. As a result, the collision load applied to the outer side wall section107ais transmitted at high efficiency to the powertrain102, which is in contact with the inner side wall section107b, through the load transmission member107L. In this way, the performance of absorbing the collision energy applied by collision from the front side of the vehicle body is further improved.

Moreover, the front vehicle body structure MK consumes the collision energy not only by deforming the suspension member104but also by changing the moving directions of the powertrain102and the vehicle body M. That is, the collision energy can be absorbed by also converting it into an energy that moves the vehicle body M away from the obstacle ST. Thus, the front vehicle body structure MK can achieve improved performance of absorbing the collision energy applied by collision from the front side of the vehicle body.

The course of change in the direction of the vehicle body M by the application of the moving force F7to the powertrain102is shown inFIGS. 20(a)-20(d).FIGS. 20(a)-20(d)are schematic views of the vehicle body M as seen from below and shows changes in state in the small overlap collision with the obstacle ST. Note that inFIGS. 20(a)-20(d), a bumper reinforcement108is illustrated which couples the tips of the front side members101L,101R to each other. Also, in order to describe the trajectory of the vehicle body M, a center portion of the coupling part104M of the suspension member in the width direction is set as a reference point P3for convenience. Note that the center portion is a portion that deforms to a relatively small extent in the collision with the obstacle ST.

FIG. 20(a)shows a state immediately before the small overlap collision with the obstacle ST, and the vehicle body M is traveling forward in the direction of arrow DR2.FIG. 20(b)shows a state immediate after the small overlap collision with the obstacle ST. In this state, the bumper reinforcement108and the lower support106are deformed toward the right side (see arrow DR3) and the add-on member104Lb is crushed. By the crush of the add-on member104Lb and the collision of the obstacle ST with the outer surface107a1, the load transmission member107L is moved toward the right rear side and collides with the left front end portion102Lt of the powertrain102. This collision applies the moving force F7to the powertrain102. The reference point P3moves from a position P3ato a position P3b. The trajectory of that movement is shown as a trajectory LN4a.

SinceFIG. 20(b)shows the state immediately after the collision, the trajectory LN4ashifts slightly to the right side near the position P3bbut is mostly straight. Due to the application of the moving force F7, the traveling direction of the powertrain102shifts to a diagonally right forward direction. This directional shift of the powertrain102changes the posture of the vehicle body M such that its front section is swung toward the right side along with the powertrain102.

FIG. 20(c)shows a state after the collision where the load transmission member107L is moved away from the obstacle ST. In this state, the moving direction of the vehicle body M shifts toward the diagonally right forward direction with the front side swung toward the right side. For this reason, a trajectory LN4bof the reference point P3from the position P3bto a position P3cin the above state is inclined greatly toward a right front side.

FIG. 20(d)shows a state after a certain period of time has further elapsed. With the powertrain102swung greatly toward the right side by the moving force F7, collision between the obstacle ST and the side sill109L is avoided. This eliminates direct influences such as entrance of the obstacle ST into the cabin RM2. Hence, the deformation of the cabin RM2is reduced.

A trajectory LN4clarifies the movement of the vehicle body M. Specifically, the trajectory LN4of the reference point P3from the position P3ato a position P3dis straight from the position P3ato a position Ps at which the collision occurs, and abruptly changes its direction toward the right front side after the collision. Thus, the trajectory LN4passes a position far from the obstacle ST. Hence, the influence of the collision on the vehicle body M is reduced.

Here, behavior during the short period of time in which the obstacle ST and the load transmission member107L come into contact with each other due to the collision will be described with reference toFIGS. 16 and 19, for example. As mentioned above, the outer surface107a1of the load transmission member107L is recessed inward from the inclination line LN1in the width direction of the vehicle body M.

First of all, the outer surface107a1is formed as a curved surface which is inclined and recessed from the outer side, and therefore has a shape in conformity with the outer shape of the obstacle ST as compared to a case where the outer surface107a1is a simple flat surface. This curved surface allows a larger area of contact between the obstacle ST and the outer surface107a1and accordingly reduces the stress in the outer surface107a1and its periphery caused by the collision load F. As result, local deformation of the load transmission member107L is reduced, and the collision load F therefore attenuates only slightly at the load transmission member107L. The collision load F is then transmitted from the outer surface107a1of the outer side wall section107ato the outer surface107b1of the inner side wall section107b. Hence, the collision load F can be transmitted more efficiently to the powertrain102.

Also, the time of contact between the obstacle ST and the outer surface107a1is longer. As a result, the time for the load transmission member107L to transmit the collision load F to the powertrain102is longer. Hence, the collision load F can be transmitted more efficiently to the powertrain102.

The behavior will be described in more detail. In the following description, to facilitate the understanding, the obstacle ST is assumed to come into point contact in the collision inFIG. 16. Moreover, for convenience, the angle θc of a tangential line LN5at a contact point P5is assumed as the collision angle.

In this case, as shown inFIG. 16, since the outer surface107a1is a concave curved surface, the contact point P5for the obstacle ST is the tip107a4at the beginning of the collision. The collision angle at this tip107a4is an angle θc1between a tangential line LN6at the tip107a4and the axis CL1in the front-rear direction and is smaller than the angle θa. That is, the collision angle at the tip107a4represents a collision at a smaller angle than the angle θb between the inclination line LN1, which connects the tip107a4and the apex107j, and the axis CL1in the front-rear direction.

As described above, the front vehicle body structure MK is advantageously such that a portion of the outer side wall section107aon the front side of the vehicle body is formed in a concave arched shape in a plan view. In this way, the obstacle ST collides with the outer side wall section107aat a shallower angle. This reduces the generation of a force in the front-rear direction which the vehicle body M receives in the collision.

In the course of the collision, the contact point PS moves on the outer surface107a1from the tip107a4toward the apex107j, and the angle θc, which is the collision angle, increases with this movement. If, for example, the add-on member104Lb is not crushed or other members are not deformed by the collision, the angle θc becomes larger than the angle θb when the contact point P5reaches the apex107j.

On the other hand, the load transmission member107L changes its posture due to crush or the like of, for example, the add-on member104Lb by the collision such that the load transmission member107L is pushed in. In this change, as shown by arrow DR4inFIG. 16, the position of the apex107jmoves toward the center of the vehicle body M. Thus, the angle θb between the tangential line LN5at the apex107jafter the movement and the axis CL1in the front-rear direction is smaller than that before the collision.

In view of this, the initial position of the load transmission member107L, the curvature of the outer surface107b1and the like are advantageously set such that the angle θb in the pushed-in posture after the collision is not larger than 45°. In other words, the collision angle θc at the contact point P5is advantageously maintained to be not larger than 45° while the contact point P5moves from the tip107a4to the apex107jwith the elapse of time in the collision.

According toFIG. 19, the lateral force fy is dominant over the axial force fx when the angle θc, which is the collision angle, is equal to or smaller than 45°. For this reason, the outer side wall section107ais advantageously formed such that the interior angle between the inclination line LN1and the axis CL1in the front-rear direction of the vehicle body is equal to or smaller than 45°. Here, the inclination line LN1is a straight line connecting the tip107a4, as the first position at which the outer side wall section107ajoins the side extension member104L, and the apex107j, as the second position at which the outer side wall section107aprotrudes outwardly furthest in the vehicle width direction. In this way, the collision angle is such that the lateral force fy is always dominant at any point of time during the collision between the obstacle ST and the load transmission member107L. Hence, the load transmission to the powertrain102through the load transmission member107L is done more efficiently.

The absorption of the collision energy by the suspension member104will now be described with reference toFIG. 21.FIG. 21is a left-side view showing the side extension member104L of the suspension member104and the front side member101L along with the dash panel103. InFIG. 21, an area AR1on the front side of the side extension member104L and an area AR2on the front side of the front side member101L are formed as sections that are mainly deformed in a frontal collision. In other words, the area AR1and the area AR2are energy absorption areas E.

In particular, the side extension member104L is advantageously provided with an energy absorption portion104Lc between the load transmission member107L which is attached to the add-on member104Lb and the coupling portion P1through which the add-on member104Lb is coupled to the base member104La. The energy absorption portion104Lc has a structure that is easily deformable by pressure.

FIG. 22is a view showing a state after a frontal collision in relation toFIG. 21. The front side member101L is deformed mostly at the energy absorption area E to absorb the energy. The side extension member104L is deformed greatly at the energy absorption portion104Lc to absorb the energy, and the deformation of the rest of the energy absorption area E is small.

As described above, in the front vehicle body structure MK, the side extension member104L is advantageously provided with the energy absorption portion104Lc, which is deformable more easily than the rest of the side extension member104L, at a portion of the side extension member104L on the rear side of the vehicle body relative to the load transmission member. In this way, in a frontal collision, the side extension member104L is deformed mainly at the energy absorption portion, which allows the side extension member104L to be deformed in a predetermined manner. As a result, the posture of the load transmission member107L in which it comes into contact with the powertrain102is stabilized, and the collision load is therefore transmitted more reliably to the powertrain102. Hence, the performance of absorbing the collision energy applied by collision from the front side of the vehicle body is maintained at a light level.

The load transmission member107L may be a load transmission member107LA without the stepped portion107a2on the outer surface107a1. The load transmission member107LA, however, has a possibility of being turned about the longitudinal axis of the side extension member104L, i.e. about the axis CL1in the front-rear direction when the side extension member104L is deformed in a small overlap collision.

FIG. 23(a)is a front view of the load transmission member107LA for explaining a state where this turn occurs. As shown inFIG. 23(a), in the load transmission member107LA, the outer surface107a1of the outer side wall section107ais an even curved surface with no step.

Most part of the housing107gof the load transmission member107LA is disposed above the side extension member104L. InFIG. 23(a), an upper left section of the housing107grelative to a center P4projects greatly. Then, when the obstacle ST collides with an entire vertical region on the outer surface107a1(a region shown by a dashed line LN7inFIG. 23(a)) at once, a counterclockwise turning force is generated. Thus, the energy absorption portion104Lc is crushed and, at the same time, its posture is turned counterclockwise (see arrow DR5). As a result, the tip side of the side extension member104L relative to the energy absorption portion104Lc appears tilted toward the left side along with the load transmission member107LA, as shown inFIG. 23(b). In this way, the efficiency of load transmission to the powertrain102may possibly be lower than that with the load transmission member107L.

On the other hand, the load transmission member107L includes the stepped portion107a2on the outer surface107a1of the outer side wall section107a. Moreover, as shown inFIG. 24, the outer surface below the position of the center P4is the lower surface107a1b, and this lower surface107a1bprotrudes outward from the upper surface107a1aabove the position of the center P4. Then, when the obstacle ST collides with the outer surface107a1, it firstly collides with only the lower surface107a1b(a region shown by a dashed line LN8inFIG. 24) and then collides with the upper surface107a1aafter the elapse of a certain period of time.

In the collision with the lower surface107a1b, the obstacle ST collides at a position below the center P4, so that a clockwise turning force is generated (arrow DR6). On the other hand, in the collision with the upper surface107a1a, a counterclockwise turning force is generated (arrow DR5).

As described above, in the front vehicle body structure MK, the side extension member104L is formed in an angular tube shape. Moreover, the load transmission member107L is fixed to the upper surface and the outer side surface, in the vehicle width direction, of the side extension member104L. Further, the outer side wall section107aand the inner side wall section107bare coupled to each other in such a way as to straddle the upper side of the side extension member104L.

Moreover, the outer side wall section107ahas the upper surface107a1awhich is the first surface on the upper side and the lower surface107a1bwhich is the second surface on the lower side. Further, the second surface (lower surface107a1b) is advantageously formed to protrude outward from the first surface (upper surface107a1a) in the vehicle width direction. In this way, the clockwise turning force generated by the obstacle ST colliding firstly with the lower surface107a1bis cancelled out by the counterclockwise turning force generated by the obstacle ST colliding thereafter with the upper surface107a1a. The side extension member104L therefore hardly turns when the energy absorption portion104Lc is crushed. Thus, the load transmission member107L comes into contact with the powertrain102with substantially no turning. Hence, the load transmission member107L can transmit the collision load at high efficiency to the powertrain102.

FIG. 25is a schematic view of the powertrain102and the load transmission members107L,107R as seen from the lower side of the vehicle body M. The following assumes that either of the load transmission members107L,107R comes into contact at its inner side wall section107bwith the powertrain102at a position P7L, P7R (contact position P7L, P7R) in a small overlap collision with the obstacle ST. An imaginary straight line connecting a support position102SL and a support position102SR at which the powertrain102is supported on the front side members101L,101R will be referred to as the coupling line LN9.

Suppose that the positions P7L, P7R are located rearward of the coupling line LN9. In this case, when a moving force F7is transmitted to the powertrain102, the rear side of the powertrain102changes its direction to the direction of the moving force F7. For this reason, the vehicle body M traveling forward changes its direction to the direction opposite to the direction of the transmitted moving force F7. As a result, the vehicle body M moves toward the obstacle ST and is therefore more greatly influenced by the obstacle ST.

On the other hand, in the front vehicle body structure MK, these positions P7L, P7R are set forward of the coupling line LN9. For this reason, when the load transmission member107L,107R transmits a moving force F7to the powertrain102in a collision with the obstacle ST, the front side of the powertrain102changes its direction to the direction of the moving force F7. Thus, as shown inFIGS. 20(a)-20(d), the vehicle body M traveling forward moves while changing its direction to a direction corresponding to the transmitted moving force F7. Hence, the vehicle body M moves away from the obstacle ST. In this way, the influence of the obstacle ST on the vehicle body M can be reduced.

As described above, the front vehicle body structure MK includes the pair of front side members101L,101R, which are provided along the front-rear direction in such a way as to sandwich the powertrain102from the opposite sides in the vehicle width direction. Moreover, the pair of front side members101L,101R support the powertrain102at the pair of support positions102SL,102SR on the opposite sides in the width direction thereof. Furthermore, the positions P7L, P7R, at which the inner side wall sections107bcome into contact with the powertrain102, are advantageously located on the front side of the vehicle body relative to the coupling line LN9, which passes the support positions102SL,102SR. In this way, when the load transmission member107L,107R transmits a moving force F7to the powertrain102in a collision with the obstacle ST, the front side of the powertrain102changes its direction to the direction of the moving force F7. Then, the vehicle body M traveling forward moves while changing its direction to a direction corresponding to the transmitted moving force F7. In other words, the vehicle body M moves away from the obstacle ST. Hence, the influence of the collision of the obstacle ST on the vehicle body M can be reduced.

In the front vehicle body structure MK, the load transmission members107L,107R are provided not on the front side members101L,101R but on the side extension members104L,104R of the suspension member104. In this way, the collision performance of the front side members101L,101R against frontal collision such as full-overlap collision is not lowered. Hence, the front vehicle body structure MK has achieved improved performance of absorbing the collision energy applied to the vehicle body in a collision from the front side.

As compared to the conventional reinforcement extension, the front vehicle body structure MK can reduce the amount of projection toward the outer side in the vehicle width direction and therefore has a high degree of freedom in design for exteriors that narrow on the front side of the vehicle body.

As described above, like the first embodiment, the front vehicle body structure according to the second embodiment also includes: a member which is provided at the side section of the vehicle body along the vehicle-body front-rear direction; and the powertrain102disposed on the inner side of the vehicle body relative to the member and fixed to the front section of the vehicle body. The front vehicle body structure further includes the load transmission member provided on the member and configured to come into contact with one end portion, in the vehicle width direction, of the powertrain when receiving a collision load applied by an obstacle from the front side of the vehicle body, and to transmit the load to the powertrain in a state of being sandwiched between the obstacle and the powertrain.

Further, in the second embodiment, the member is the suspension member104including the pair of left and right side extension members104provided along the vehicle-body front-rear direction in such a way as to sandwich the powertrain102from the opposite sides in the vehicle width direction. Also, the load transmission member107is attached to the side extension member104. Moreover, the load transmission member includes: the outer side wall section107abeing formed to project outward further in the vehicle width direction from the side extension member as extending toward to the rear side of the vehicle body; and the inner side wall section107bprojecting from the side extension member to a position inward from the side extension member in the vehicle width direction and being disposed to face the powertrain. Further, the side extension member104is deformed to bring the inner side wall section107binto contact with the powertrain102when the collision load is applied to the outer side wall section107aof the load transmission member107. As described above, the collision load is transmitted at high efficiency through the load transmission member to the powertrain which is in contact with the inner side wall section. Hence, the collision energy applied by a collision from the front side of the vehicle body can be absorbed efficiently.

The entire contents of Japanese Patent Application No. 2013-079151 (filed on Apr. 5, 2013) and Japanese Patent Application No. 2013-173402 (filed on Aug. 23, 2013) are incorporated herein.

The present invention has been described above through specific embodiments. However, it is apparent to those skilled in the art that the present invention is not limited the above description, and various changes and modifications can be made.

According to one or more embodiments of the present invention, when receiving a collision load from the front side of the vehicle, the load transmission member transmits the load from the obstacle to the powertrain while turning along with the powertrain in the state of being sandwiched between the obstacle and the powertrain. Thus, the collision load received by the load transmission member is efficiently transmitted to the vehicle body through the powertrain. Hence, enhanced performance of absorbing collision load from the front side of the vehicle body can be achieved.

REFERENCE SIGNS LIST

1, M vehicle body3,3A obstacle5,101,101L,101R front side member9,9A,107,107L,107R,107LA load transmission member11cross member23,102powertrain102SL,102SR support position104suspension member104L,104R side extension member104Lc energy absorption portion107aouter side wall section107binner side wall sectionCL1axis in vehicle-body front-rear directionMK front vehicle body structure