Patent ID: 12187111

DETAILED DESCRIPTION

A lower structure for a vehicle1of the present disclosure will hereinafter be described with reference to drawings, the lower structure being applied as an embodiment of the present disclosure to a plug-in hybrid automobile (PHEV).

Further, in the drawings, an arrow F indicates a front direction of the vehicle1, an arrow R indicates a right direction of the vehicle1, an arrow L indicates a left direction of the vehicle1, and an arrow U indicates an upper direction of the vehicle.

As illustrated inFIG.1andFIG.2, the vehicle1of the present disclosure is configured to include a vehicle body2, battery units20disposed under a floor of the vehicle body2, and so forth.

Note that in the vehicle body2, in front of a vehicle cabin, a power unit room is provided which houses a power unit configured with an engine, a motor, and so forth appropriately used for electricity generation or driving.

As illustrated inFIG.1andFIG.2, in a lower portion of the vehicle cabin of in the vehicle body2, a floor panel4constituting a vehicle body floor is disposed.

The floor panel4includes a front floor panel5and a rear floor panel6, and the front floor panel5and the rear floor panel6are joined together to be continuous with each other between front and rear sides via a kick-up portion which is.

In the front floor panel5, a tunnel portion7(also referred to as “floor tunnel7”) is integrally or substantially integrally formed which swells upward (toward the vehicle cabin) in a vehicle-width-direction center portion and is provided to extend in a front-rear direction of the vehicle1.

This tunnel portion7serves as a center of vehicle body rigidity and is formed in the front-rear direction throughout substantially the whole length of the floor panel4.

As illustrated inFIG.1andFIG.2, left and right tunnel side members8are provided which extend in the front-rear direction of the vehicle body2along both of left and right lower edges of the tunnel portion7under the floor panel4. Closed cross-sections8sextending in the front-rear direction of the vehicle1are respectively formed between the tunnel side members8and the above-described floor panel4.

Further, as illustrated inFIG.1andFIG.2, side sills9extending in the front-rear direction are connected with both outer sides (both of left and right sides) of the above-described floor panel4in its width direction. The side sill9is a frame member in which a side sill inner9a(seeFIG.1) and a side sill outer9bare joined together and which has a closed cross-section9sextending throughout substantially the whole length of the floor panel4in the front-rear direction.

Floor frames10as left and right frame members which protrude downward and extend in the front-rear direction are provided under the floor panel4and between side ends of the floor panel4and the tunnel portion7, specifically between the side sill inners9aand the tunnel side members8. A closed cross-section10sextending in the front-rear direction is formed between the floor frame10and the floor panel4.

A rear portion10rof the floor frame10is adjacent to the side sill9on an inner side in a vehicle width direction and extends in the front-rear direction substantially in parallel with the side sill9.

As described above, the rear floor panel6is disposed in the rear of the front floor panel5. On both outer sides of the rear floor panel6in the vehicle width direction, rear side frames11are disposed which extend in the front-rear direction of the vehicle1. A front portion11fof the rear side frame11extends forward to a vehicle-width-direction outer side of a rear portion of the front floor panel5. That is, the front portion11fof the rear side frame11is adjacent to a rear portion of the side sill9on the inner side in the vehicle width direction and extends in the front-rear direction substantially in parallel with the side sill9. Furthermore, a front end of the rear side frame11is joined to a back end of the floor frame10.

Front portions10fof the floor frames10are inclined and linearly extend to be positioned vehicle-width-direction inner sides toward the front, and front ends of the front portions10fare joined to back ends of front side frames as frame members which extend in the front-rear direction on both sides of the power unit room provided in front of the vehicle cabin in the vehicle body2.

Further, as illustrated inFIG.2, in an intermediate position of the side sill9in the front-rear direction, a center pillar12(the center pillar12on a left side of the vehicle body2is illustrated) is provided which extends upward from the intermediate position. The center pillar12is a frame member which includes a center pillar outer12aand a center pillar inner and in which a closed cross-section12sextending in an up-down direction is formed.

Further, an exhaust apparatus60(seeFIG.1) is connected, via an exhaust manifold, with exhaust ports provided to the engine installed in front of the vehicle cabin in the vehicle body2. The exhaust apparatus60is disposed to be continuous in the front-rear direction of the vehicle1in a lower position than a lower end of the floor panel4.

As illustrated inFIG.1, the exhaust apparatus60includes various kinds of exhaust system members61, such as a catalytic unit, a silencer, and a tail pipe, and includes exhaust pipes62which are arranged among the various kinds of exhaust system members61and connect together the exhaust system members61neighboring in the front-rear direction.

A reference character61ain the drawings denotes the catalytic unit among the exhaust system members61. Further,FIG.2does not illustrate the exhaust apparatus60.

The exhaust apparatus60formed with those elements is disposed to be continuous in the front-rear direction of the vehicle1in a lower position than the lower end of the floor panel4.

Specifically, as illustrated inFIG.1, the exhaust apparatus60is routed to make a detour on one side (the right side in this example) of vehicle-width-direction outer sides of the tunnel portion7in a front portion of the front floor panel5and in a rear portion of the rear floor panel6in the front-rear direction. Meanwhile, the exhaust apparatus60is routed immediately below the tunnel portion7in the rear portion of the front floor panel5in the front-rear direction.

Under the floor panel4, insulators65,66, and67are disposed along the longitudinal direction (exhaust path) of the exhaust apparatus60. The insulators65,66, and67are formed in shapes protruding upward such that their orthogonal cross-sections in the longitudinal direction of the exhaust apparatus60open downward. Furthermore, the insulators65,66, and67house the exhaust apparatus60in their internal portions to prevent a periphery from being damaged by heat of the exhaust apparatus60.

As the insulators65,66, and67, a front portion insulator65, an intermediate portion insulator66, and a rear portion insulator67are provided. Those insulators65,66, and67are formed while being divided from each other and are mounted on the vehicle body2in a state where those are coupled together to be continuous in the front-rear direction.

As illustrated inFIG.1andFIG.2, the battery units20are disposed on lower sides of the rear portion of the front floor panel5.

However, as in the vehicle1of the present disclosure, in a plug-in hybrid vehicle (PHEV) which is capable of being charged with electrical energy directly from a commercial electric outlet, because a battery is large-sized and has a large capacity, to handle this, the battery units20are disposed while being spaced apart from each other on left and right sides across the tunnel portion7on the lower side of the floor panel4.

Here, of the battery units20on the left and right sides, a battery unit20L on the left side will also be referred to as “a first battery unit20L”, and the right battery unit20on the right side will also be referred to as “a second battery unit20R”.

Note that the first battery unit20L and the second battery unit20R are spaced apart from each other on the left and right sides across the tunnel portion7but are electrically connected with each other.

As illustrated inFIG.1andFIG.2, each of the first and second battery units20L and20R is configured as a battery pack which has a battery module21(battery module) and a battery case22as a battery case for housing the battery module21. The vehicle1travels by using electrical energy stored in the battery modules21housed in the battery cases22in addition to drive by the engine.

In one or more aspects of the disclosed subject matter, the battery module21is configured in a state where plural battery cells, which are formed into flat plate shapes extending in the up-down direction and the front-rear direction, are stacked in the vehicle width direction. For example, the battery cell is a secondary battery such as a lithium-ion battery and a nickel-metal hydride battery.

The battery case22is formed into a box shape with a tray221which supports the battery module21from a lower side and a lid222(the lid222on the left side of the vehicle1is illustrated) which covers the battery module21from above. A flange portion221ais formed in an outer peripheral edge of the tray221in a planar view, and the flange portion221ais fastened to an outer peripheral edge of the lid222in a planar view in a state where the battery module21is housed in an internal portion.

Further, as illustrated inFIG.1andFIG.2, the first and second battery units20L and20R are disposed on the vehicle-width-direction inner sides of the rear portions10rof the floor frame10and the front portions11fof the rear side frames11, the rear portions10rand front portions11frespectively corresponding to the battery units20L and20R on the left and right, and on the vehicle-width-direction outer sides of the tunnel portion7.

Further, each of the first and second battery units20L and20R is fastened and fixed to plural frame members, around which the battery case22is disposed and which will be described later, through plural parts by using bolts and so forth, via brackets15,30, and so forth.

Specifically, on the vehicle-width-direction inner side, each of the first and second battery units20L and20R is fixed to the tunnel portion7as a frame member, which is adjacent thereto on the vehicle-width-direction inner side, via a bracket.

Meanwhile, on the vehicle-width-direction outer sides, both of the first and second battery units20L and20R are fixed to the rear portions10rof the floor frames10as frame members, which are adjacent thereto on the vehicle-width-direction outer sides, via the intermediate brackets15and are fixed to the front portions11fof the rear side frames11via rear-side brackets30L and30R. Specific structures of the above-described intermediate bracket15and rear-side brackets30L and30R will be described later.

Further, the above-described intermediate portion insulator66is positioned between the first and second battery units20L and20R below the tunnel portion7. Furthermore, as illustrated inFIG.1andFIG.2, below the above-described intermediate portion insulator66and between the first and second battery units20L and20R, a coupling member24is disposed which couples those first and second battery units20L and20R with each other.

Specifically, the coupling member24extends in the vehicle width direction so as to close, from below, the intermediate portion insulator66opening downward and couples together, in the vehicle width direction, a vehicle-width-direction inner side of a bottom surface of the first battery unit20L and a vehicle-width-direction inner side of a bottom surface of the second battery unit20R.

Below a front portion of the floor panel4, that is, in front of the first battery unit20L, the inverter13as a high-voltage device is provided.

The inverter13is a conversion device which performs mutual conversion between power of a direct-current circuit in which the battery units20are interposed and power of an alternating-current circuit in which a motor is interposed.

The inverter13is arranged between a front portion of the floor frame10and a front portion of the tunnel side member8on one side (the left side of the vehicle1in this example) in the vehicle width direction and is attached and fixed to the front portion10fof the floor frame10and the front portion of the tunnel side member8.

The first battery unit20L and the inverter13are coupled with each other via a high-voltage cable14(high-voltage harness). In the present embodiment, as for the high-voltage cable14, a front-side plug14fis connected with a rear portion of the inverter13, a rear-side plug14ris connected with a front portion of the first battery unit20L (specifically, a portion in front of the position of the center of gravity of the first battery unit20L), and the high-voltage cable14extends in a substantially front-rear direction between the front portion of the first battery unit20L and the rear portion of the inverter13.

Accordingly, when the motor is driven, alternating-current driving electric power is supplied from the first and second battery units20L and20R side to the motor side via the high-voltage cable14. When the motor generates electricity, direct-current charging electric power is supplied from the motor side to the first and second battery units20L and20R side via the high-voltage cable14.

Note that front areas of the battery units20around a lower surface of the floor panel4are covered by undercovers. The undercovers are respectively provided to a region on one side and a region on the other side in the vehicle width direction with respect to the insulator65, the regions being on a lower side of the front portion of the floor panel4. Both of the pair of undercovers are arranged at heights substantially flush with lower surfaces of the battery units20and with a lower end of the insulator65, and portions of the undercovers are joined to the lower surfaces of the battery units20and the lower end of the insulator65, the portions being adjacent to those.

Further, as illustrated inFIG.1andFIG.2, as for the above-described intermediate bracket15, the pair of left and right intermediate brackets15are provided, and both of those are provided in the positions corresponding to the center pillars12(seeFIG.2) (substantially intermediate positions of the side sills9in the front-rear direction) in the front-rear direction and on the vehicle-width-direction outer sides respectively corresponding to the first and second battery unit20L and20R. The intermediate bracket15is formed into a general L-shape with a battery-side mounting piece151which extends in the up-down direction in an orthogonal cross-sectional view to the front-rear direction and a vehicle-body-side mounting piece152which extends from a lower portion of the battery-side mounting piece151to the vehicle-width-direction outer side.

Furthermore, in the intermediate bracket15, the battery-side mounting piece151is fastened and fixed to a side surface of the battery case22on the vehicle-width-direction outer side by bolts and so forth, and the vehicle-body-side mounting piece152is fastened and fixed to the rear portion10rof the floor frame10by bolts and so forth.

Further, the above-described rear-side brackets30L and30R are provided on left and right sides, and each of those is a bracket which fixes the battery case22to the vehicle body2(a bottom face portion of the front portion11fof the rear side frame11) in a rear portion (specifically, a rear area relative to the position of the center of gravity of the battery case22) and on a side surface of the battery case22on the vehicle-width-direction outer side and is formed by performing a bending process for a steel plate or the like by press molding or the like.

Between the pair of left and right rear-side brackets30L and30R, the rear-side bracket30L on a vehicle left side is a bracket which fixes a rear portion of the first battery unit20L to the vehicle body2(the bottom face portion of the front portion11fof the rear side frame11) from the vehicle-width-direction outer side and corresponds to a fixing member of the present disclosure.

This rear-side bracket30L is configured to be capable of being fractured when an inward collision load in the vehicle width direction is input from the left side of the vehicle1to a position in front of the position of the center of gravity of the first battery unit20L (for example, the position corresponding to the center pillar12in the front-rear direction) (in other words, when a side collision from the left side of the vehicle1occurs).

Meanwhile, between the pair of left and right rear-side brackets30L and30R, the rear-side bracket30R on a vehicle right side is formed stronger than the rear-side bracket30L on the vehicle left side while priority is given to durability (rigidity) against a vibration input from the second battery unit20R in usual traveling.

In the following, a configuration of the rear-side bracket30L on the vehicle left side will be described.

As illustrated inFIG.3toFIG.5, the rear-side bracket30L is integrally formed with a vehicle-width outward extension piece31which extends in the vehicle width direction and a downward extension piece32which extends downward from a vehicle-width-direction inner end of the vehicle-width outward extension piece31in the vehicle width direction. A bent portion36positioned at a corner portion between the vehicle-width outward extension piece31and the downward extension piece32is formed throughout substantially the whole length of the rear-side bracket30L in the front-rear direction.

In the vehicle-width outward extension piece31, a front-side flange33is provided to a front portion, a vehicle-body-side mounting portion34is provided to an intermediate portion in the front-rear direction, a rear-side flange35is provided to a rear portion, and those are continuously formed in the front-rear direction. Each of the front-side flange33, the vehicle-body-side mounting portion34, and the rear-side flange35extends to the vehicle-width-direction outer side and is formed in an eaves shape with respect to the downward extension piece32. The vehicle-body-side mounting portion34is formed to protrude to the vehicle-width-direction outer side of the front-side flange33and the rear-side flange35.

The front-side flange33is inclined and linearly extends from a front end of the vehicle-body-side mounting portion34along the bent portion36to be positioned lower toward the front. Meanwhile, the rear-side flange35extends rearward from a back end of the vehicle-body-side mounting portion34along the bent portion36.

In a front-side section of the vehicle-body-side mounting portion34, a pin insertion hole341is formed which passes through in the up-down direction and through which a pin P (seeFIG.3andFIG.4) is capable of being inserted. A rear-side section of the vehicle-body-side mounting portion34, a bolt insertion hole342is formed which passes through in the up-down direction and through which a bolt B34(seeFIG.3andFIG.4) is capable of being inserted.

Accordingly, the rear-side bracket30L is positioned to the vehicle body2(the bottom face of the front portion11fof the rear side frame11) by using the pin P in the pin insertion hole341of the vehicle-body-side mounting portion34. In addition, in such a positioned state, the rear-side bracket30L is fastened and fixed to the vehicle body2(the bottom face) by using the bolt B34and so forth in the bolt insertion hole342of the vehicle-body-side mounting portion34. That is, the bolt B34which is inserted through the bolt insertion hole342of the vehicle-body-side mounting portion34is formed as a vehicle-body fastening portion B34which is fastened to the vehicle body2.

In the downward extension piece32in the rear-side bracket30L, a battery-side mounting piece41is formed from a front portion to an intermediate portion in the front-rear direction, a rearward extension piece47is formed in a rear portion, and those battery-side mounting piece41and the rearward extension piece47are continuously formed throughout the downward extension piece32in the front-rear direction. Each of the battery-side mounting piece41and the rearward extension piece47extends downward in a perpendicular direction from the vehicle-width-direction inner end of the vehicle-width outward extension piece31via the bent portion36, and the battery-side mounting piece41is formed to protrude to a lower area than the rearward extension piece47.

In a vehicle side view, the above-described rearward extension piece47substantially horizontally extends from a base portion of the battery-side mounting piece41(that is, a joint portion between an upper edge side41uand a rear edge side41r, which will be described later). The rearward extension piece47is formed while having a bent portion46in an intermediate portion in the front-rear direction such that a rear portion (distal end portion) is slightly directed to the vehicle-width-direction inner side with respect to a front portion (base portion). In the rear portion of the rearward extension piece47, a through hole48for mounting a harness is formed.

As illustrated inFIG.3toFIG.5, the battery-side mounting piece41is integrally formed to include the upper edge side41uwhich is inclined and substantially linearly extends in an upper edge of the battery-side mounting piece41to be positioned lower toward the front in a vehicle side view, the rear edge side41rwhich is inclined and linearly extends in a rear edge of the battery-side mounting piece41at a steeper slope than the upper edge side41uto be positioned lower toward the front in a vehicle side view, a front edge side41fwhich linearly extends downward in the perpendicular direction from a front lower end of the upper edge side41u, and a lower edge side41dwhich linearly extends in the front-rear direction to connect together a front lower end of the rear edge side41rand a lower end of the front edge side41f. Because the lower end of the front edge side41fand the front lower end of the rear edge side41rare positioned at substantially the same height, the lower edge side41dextends horizontally in the front-rear direction.

In other words, in a center portion of the battery-side mounting piece41in a side view, a hole portion41his formed which passes through the battery-side mounting piece41in the vehicle width direction (plate-thickness direction). The hole portion41his defined by the upper edge side41u, the rear edge side41r, the front edge side41f, and the lower edge side41dwhich are positioned in an outer periphery of the battery-side mounting piece41.

In the above-described battery-side mounting piece41, plural (three in this example) bolt insertion holes42,43, and44are formed which pass through in the vehicle width direction (plate thickness direction) and through which bolts B42, B43, and B44are capable of being inserted.

The bolt insertion hole42is formed in an upper portion of the front edge side41fof the battery-side mounting piece41, the bolt insertion hole43is formed in a lower end portion of the rear edge side41r(a corner portion between the rear edge side41rand the lower edge side41d) in the battery-side mounting piece41, the bolt insertion hole44is formed in a lower end portion of the front edge side41f(a corner portion between the front edge side41fand the lower edge side41d) in the battery-side mounting piece41, and those are respectively set as a first bolt insertion hole42, a second bolt insertion hole43, and a third bolt insertion hole44.

Furthermore, as illustrated inFIG.3andFIG.4, the above-described rear-side bracket30L is fastened and fixed to the side surface of the battery case22on the vehicle-width-direction outer side by using the bolts B42, B43, and B44and so forth in the respective bolt insertion holes42,43, and44of the battery-side mounting piece41. That is, the bolt B42which is inserted through the first bolt insertion hole42is formed as a first battery fastening portion B42which is fastened to the battery case22. Similarly, the bolt B43which is inserted through the second bolt insertion hole43is formed as a second battery fastening portion B43which is fastened to the battery case22, and the bolt B44which is inserted through the third bolt insertion hole44is formed as a third battery fastening portion B44which is fastened to the battery case22.

Each of the first to third battery fastening portions B42, B43, and B44is positioned lower than the vehicle-body fastening portion B34. Further, the first battery fastening portion B42and the third battery fastening portion B44is positioned in front of the second battery fastening portion B43, and the second battery fastening portion B43and the third battery fastening portion B44are positioned below the first battery fastening portion B42.

In addition, the third battery fastening portion B44is positioned immediately below the first battery fastening portion B42and is positioned at substantially the same height as the second battery fastening portion B43.

Further, as illustrated inFIG.4andFIG.6, the first and second battery fastening portions B42and B43are provided such that a front-rear direction length L1′ between the vehicle-body fastening portion B34and the first battery fastening portion B42(the length L1′ of a front-rear direction component of a length L1between the vehicle-body fastening portion B34and the first battery fastening portion B42) becomes longer than a front-rear direction length L2′ between the vehicle-body fastening portion B34and the second battery fastening portion B43(the length L2′ of a front-rear direction component of a length L2between the vehicle-body fastening portion B34and the second battery fastening portion B43).

In addition, the battery-side mounting piece41of the rear-side bracket30L is configured to be capable of being fractured when an inward collision load in the vehicle width direction is input from the left side of the vehicle1to a position in front of the position of the center of gravity of the first battery unit20L (for example, the position corresponding to the center pillar12(seeFIG.2) in the front-rear direction) (in other words, when a side collision from the left side of the vehicle1occurs).

Specifically, as illustrated inFIG.3toFIG.5, a constricted portion45as a strength lowered portion is formed in a vicinity section in the first battery fastening portion B42to the vehicle-body fastening portion B34side (in this example, a corner portion (boundary portion) between the upper edge side41uand the front edge side41f).

Specifically, in the constricted portion45, at least one edge portion, in a width direction, of the vicinity section in the first battery fastening portion B42to the vehicle-body fastening portion B34side (in this example, an edge portion in front of and above the corner portion between the upper edge side41uand the front edge side41f) is formed in a shape recessed rearward and downward. Accordingly, the constricted portion45is formed, as a strength lowered portion, to locally have a small width compared to a peripheral portion and is formed as a fragile portion (small width portion) to be preferentially fractured in a side collision.

Here, in a side collision from the left side of the vehicle1, behavior occurs where the side sill9or the like as a frame member (outside frame member) positioned on the vehicle-width-direction outer side (in this example, the left side of the vehicle1) of the first battery unit20L is subjected to bending deformation to the vehicle-width-direction inner side and pushes the front portion of the first battery unit20L into the vehicle-width-direction inner side. In response to that, the rear portion of the first battery unit20L is pulled to the vehicle-width-direction outer side by the front portion11fof the rear side frame11via the rear-side bracket30L.

Due to this, in the rear-side bracket30L, between the first and second battery fastening portions B42and B43and the vehicle-body fastening portion B34, respective load transmission paths are configured which connect those in the shortest lengths.

As illustrated inFIG.4, between those load transmission paths, the load transmission path between the first battery fastening portion B42and the vehicle-body fastening portion B34is set as a first load transmission path P1, and the load transmission path between the second battery fastening portion B43and the vehicle-body fastening portion B34is set as a second load transmission path P2.

That is, the first load transmission path P1is formed along the upper edge side41uof the battery-side mounting piece41, and the second load transmission path P2is formed along the rear edge side41rof the battery-side mounting piece41.

Here, the front-side flange33extends in an upper edge of the first load transmission path P1which is formed along the upper edge side41uof the battery-side mounting piece41.

However, a front lower end33a(an end portion on the first battery fastening portion B42side) in the front-side flange33is positioned in an edge portion above and in the rear of the constricted portion45. That is, the front-side flange33extends forward along the first load transmission path P1to the edge portion above and in the rear of the constricted portion45. Thus, above the constricted portion45, the front-side flange33is not formed.

Next, a description will be made, by usingFIG.7about behavior in a case where, as described above, in a side collision, a tension load to the vehicle-width-direction outer side is input to the rear-side bracket30L of the present disclosure and the rear-side bracket30L is thereby fractured.

FIG.7is a perspective view which, in a manner corresponding toFIG.3, illustrates results of a simulation analysis of behavior of the rear-side bracket30L in a side collision.FIG.7(a)illustrates a side collision early period,FIG.7(b)illustrates a side collision intermediate period, andFIG.7(c)illustrates a side collision later period.

Note thatFIG.7(a),FIG.7(b), andFIG.7(c)illustrate the distribution of bending stress (moment load) in each portion of the rear-side bracket30L based on shades by dots and illustrate that a portion with denser dots has high bending stress.

First, in a side collision, a tension load to the vehicle-width-direction outer side is input from the vehicle body2to the vehicle-body fastening portion B34of the rear-side bracket30L. In other words, as illustrated inFIG.6, a load F1by which the first battery fastening portion B42is pulled to a vehicle-width inner side and a load F2by which the second battery fastening portion B43is pulled to the vehicle width inner side are input from the first battery unit20L.

Specifically, a load input from the vehicle-body fastening portion B34to the rear-side bracket30L is transmitted to the first battery fastening portion B42along the first load transmission path P1and is transmitted to the second battery fastening portion B43along the second load transmission path P2.

Here, as described above, the front-rear direction length L1′ (also referred to as “front moment length L1′”) between the vehicle-body fastening portion B34and the first battery fastening portion B42is set longer than the front-rear direction length L2′ (also referred to as “rear moment length L2′”) between the vehicle-body fastening portion B34and the second battery fastening portion B43.

Thus, when the tension load to the vehicle-width-direction outer side is input from the vehicle body2to the vehicle-body fastening portion B34of the rear-side bracket30L in the side collision early period, a larger moment acts on the first battery fastening portion B42than the second battery fastening portion B43.

Accordingly, as illustrated inFIG.7(a), in the side collision early period, stress (moment load) can be concentrated more in the vicinity of the first battery fastening portion B42than the vicinity of the second battery fastening portion B43.

Here, because, in the rear-side bracket30L, the tension load acting on the rear-side bracket30L in a side collision causes stress to be concentrated in the vicinities in the first battery fastening portion B42and the second battery fastening portion B43to the vehicle-body fastening portion B34side, as illustrated inFIG.4, those can be fractured along a fracturing line CL which linearly connects those together.

Furthermore, the second battery fastening portion B43is set to be positioned below the first battery fastening portion B42, and the fracturing line CL can thereby be set as a linear shape extending in an upper-front-to-lower-rear direction as illustrated inFIG.4.

On the other hand, as illustrated inFIG.4, in a case where a fastening portion B′ is hypothetically present in a predetermined position between the vehicle-body fastening portion B34and the second battery fastening portion B43, stress to be more actively transmitted from the vehicle body2side (the vehicle-body fastening portion B34side) to the first battery fastening portion B42than the second battery fastening portion B43is also dispersed to the fastening portion B′ in addition to the first battery fastening portion B42and the second battery fastening portion B43. Then, stress which should basically be transmitted to the first battery fastening portion B42becomes small, and the rear-side bracket30L might not be capable of being detached from the first battery unit20L at a desired timing.

Thus, as described above, the fracturing line CL is set as the linear shape extending in the upper-front-to-lower-rear direction, and further a configuration is made such that another fastening portion such as the fastening portion B′ is not provided on the vehicle-body fastening portion B34side of the fracturing line CL between the vehicle-body fastening portion B34and the second battery fastening portion B43(seeFIG.4). Accordingly, in the side collision early period, stress can be concentrated in the first battery fastening portion B42.

In addition, as illustrated inFIG.3andFIG.4, as described above, the constricted portion45is provided in the vicinity section in the first battery fastening portion B42to the vehicle-body fastening portion B34side. Thus, stress can be concentrated in the constricted portion45in the vicinity of the first battery fastening portion B42(see the dotted region inFIG.7(a)which corresponds to the constricted portion45).

Thus, as illustrated inFIG.7(b), in the side collision intermediate period, the constricted portion45is fractured in which stress is concentrated, as described above, in the vicinity of the first battery fastening portion B42. Accordingly, because stress is concentrated in the vicinity of the second battery fastening portion B43, in the side collision later period, as illustrated inFIG.7(c), the vicinity of the second battery fastening portion B43is fractured.

In short, the rear-side bracket301, is configured to stepwise fracture the vicinity of the first battery fastening portion B42and the vicinity of the second battery fastening portion B43in a side collision and to thereby certainly fracture both of those.

As illustrated inFIG.1andFIG.2, the above-described lower structure for the vehicle includes the first battery unit20L (battery unit) provided under the floor panel4constituting the vehicle body floor, a frame member which extends in the front-rear direction on the vehicle-width-direction outer side of the first battery unit20L and which will be described later, the high-voltage cable14which extends forward from the front portion of the first battery unit20L, and the rear-side bracket30L as a fixing member which fixes the rear portion of the first battery unit20L to a frame member.

In addition, as illustrated inFIG.1andFIG.2, the lower structure for the vehicle1includes the side sills9and the floor frames10and rear side frames11which are adjacent to the side sills9on the vehicle-width-direction inner sides and extend in the front-rear direction. The floor frame10is provided in front of the rear side frame11, the back end of the floor frame10and the front portion11fof the rear side frame11are joined to each other, and the rear portion of the first battery unit20L is fixed to the front portion11fof the rear side frame11as a frame member via the rear-side bracket30L.

Furthermore, the lower structure for the vehicle1is characterized in that the rear-side bracket30L is configured to be capable of being fractured when an inward collision load in the vehicle width direction is input to a position in front of the position of the center of gravity of the first battery unit20L.

In the above configuration, because rotation behavior of the first battery unit20L can be inhibited in a side collision, an excessive tension can be inhibited from being exerted on the high-voltage cable14which extends forward from the front portion of the first battery unit20L.

In detail, when from a normal (ordinary) state illustrated inFIG.1, as illustrated inFIG.8, a collision object80such as a pole collides, inward in the vehicle width direction from the vehicle-width-direction outer side (in this example, the left side of the vehicle body2), with the vehicle body2in a front area of the vehicle1relative to the position of the center of gravity of the first battery unit20L, the side sill9deforms in a V-shape in a vehicle planar view.

Then, because the front portion11fof the rear side frame11which is positioned in the rear of a collision position of the collision object80is likely to be displaced to the vehicle-width-direction inner side toward the front, a tension load to the vehicle-width-direction outer side is input from the rear side frame11(vehicle body2) side to the rear-side bracket30L fixed to the front portion11fof the rear side frame11.

Here, a rear-side bracket300included in a lower structure100for a vehicle in a prior art example (comparative example) as illustrated inFIG.9is formed strong while priority is given to durability (rigidity) against a vibration input from the first battery unit20L in usual traveling. Thus, in the lower structure100for a vehicle in the prior art, even when a tension load to the vehicle-width-direction outer side is input from the vehicle body2side as described above in a side collision, as illustrated inFIG.10, the first battery unit20L and the front portion11fof the rear side frame11are maintained in a state where those are fixed to each other via the rear-side bracket300.

In this case, in a side collision, the rear portion of the first battery unit20L is likely to be displaced to the vehicle-width-direction outer side following deformation of the front portion11fof the rear side frame11in which the front portion11fis inclined to the vehicle-width-direction inner side toward the front.

That is, as illustrated inFIG.10, the front portion of the first battery unit20L is pushed into the vehicle-width-direction inner side due to an inward collision by the collision object80in the vehicle width direction, the tunnel portion7is thereby subjected to compressive deformation in the vehicle width direction, the rear portion of the first battery unit20L is pulled to the vehicle-width-direction outer side by the front portion11fof the rear side frame11via the rear-side bracket30L (see an arrow D1inFIG.10), and the first battery unit20L thereby exhibits behavior of rotating counterclockwise in a bottom view (see an arrow D2inFIG.10). In such a case, it is concerned that in response to the rotation behavior of the first battery unit20L, a tension load is exerted on the high-voltage cable14which extends forward from the front portion of the first battery unit20L.

On the other hand, in the lower structure for the vehicle1, as illustrated inFIG.8, the rear-side bracket30L is configured to be fractured by an input, from the vehicle body2side, of a tension load to the vehicle-width-direction outer side in a side collision from the left side of the vehicle1. Thus, the rear portion of the first battery unit20L can be detached from the front portion11fof the rear side frame11(vehicle body2) (seeFIG.8).

Thus, in a side collision, the rear portion of the first battery unit20L is not pulled to the vehicle-width-direction outer side by the side sill9and so forth via the rear-side bracket30L and does not follow deformation in rear portions of the side sill9and so forth in which the rear portions are inclined to the vehicle-width-direction inner side toward the front.

Consequently, in a side collision, counterclockwise rotation behavior of the first battery unit20L in which the front portion is more largely displaced to the vehicle-width-direction inner side than the rear portion can be inhibited, and a tension load can be inhibited from being exerted on the high-voltage cable14, which extends forward from the front portion of the first battery unit20L, in response to the rotation behavior.

In addition, because the high-voltage cable14extending forward does not have to be formed excessively long by being provided with an extra length portion for an actual length taking exertion of a tension load in a side collision into consideration, an increase in an electric resistance of the high-voltage cable14can be inhibited.

As illustrated inFIG.3andFIG.4, as a form of a working example of the present disclosure, the rear-side bracket30L is configured to have the vehicle-body fastening portion B34, the first and second battery fastening portions B42and B43which are positioned below the vehicle-body fastening portion B34and are spaced apart in the front-rear direction, and the hole portion41hwhich is formed between the first battery fastening portion B42and the second battery fastening portion B43.

In the above configuration, the load transmission paths P1and P2(seeFIG.4) of loads transmitted from the vehicle-body fastening portion B34to the first battery unit20L side can be divided into both sides across the hole portion41hprovided between the first battery fastening portion B42and the second battery fastening portion B43. Thus, in a side collision, a load input from the vehicle body2to the rear-side bracket30tvia the vehicle-body fastening portion B34is not dispersed between the first battery fastening portion B42and the second battery fastening portion B43but can be concentrated in the vicinities of those battery fastening portions B42and B43.

Further, because the hole portion41hcontributes to lowering of strength of the vicinities of the first and second battery fastening portions B42and B43, a portion between the first battery fastening portion B42and the second battery fastening portion B43is stretched in a side collision, and the vicinities of the first and second battery fastening portions B42and B43are thereby not hindered from being fractured.

Consequently, in a side collision, the vicinity of the first battery fastening portion B42and the vicinity of the second battery fastening portion B43can certainly be fractured.

As illustrated inFIG.4, as a form of a working example of the present disclosure, the first battery fastening portion B42is configured to be positioned in front of the second battery fastening portion B43, the front-rear direction length L1′ between the vehicle-body fastening portion B34and the first battery fastening portion B42is configured to be longer than the front-rear direction length L2′ between the vehicle-body fastening portion B34and the second battery fastening portion B43.

That is the front moment length L1′ is set longer than the rear moment length L2′.

In a side collision, because the rear-side bracket30L is pulled to the vehicle-width-direction outer side by the vehicle body2, a tension load F1to the vehicle-width-direction inner side acts on the first battery fastening portion B42, and a tension load F2to the vehicle-width-direction inner side acts on the second battery fastening portion B43(seeFIG.6).

Thus, in the above configuration, in a side collision, because a moment load can more be concentrated in the vicinity of the first battery fastening portion B42than the vicinity of the second battery fastening portion B43, the vicinity of the first battery fastening portion B42and the vicinity of the second battery fastening portion B43can stepwise be fractured in this order.

Consequently, in a side collision, both of the vicinity of the first battery fastening portion B42and the vicinity of the second battery fastening portion B43can certainly be fractured.

As illustrated inFIG.3andFIG.4, as a form of a working example of the present disclosure, the second battery fastening portion B43is configured to be positioned below the first battery fastening portion B42.

In the above configuration, as illustrated inFIG.4, the desired fracturing line CL of the rear-side bracket30L fractured by a tension load acting on the rear-side bracket30L in a side collision can be set as a straight line which connects together, in the upper-front-to-lower-rear direction, the respective vicinities in the first battery fastening portion B42and the second battery fastening portion B43to the vehicle-body fastening portion B34side.

That is, as described above, the second battery fastening portion B43is positioned below the first battery fastening portion B42, and the rear-side bracket30L is thereby configured such that the fastening portion B′ is not provided in a position between the vehicle-body fastening portion B34and the second battery fastening portion B43, that is, on the vehicle-body fastening portion B34side of the fracturing line CL (seeFIG.4). Accordingly, in a side collision, stress is not dispersed to the fastening portion B′, but stress can be concentrated in the first battery fastening portion B42.

As illustrated inFIG.3andFIG.5, as a form of a working example of the present disclosure, the constricted portion45as a strength lowered portion is provided in the vicinity in the first battery fastening portion B42to the vehicle-body fastening portion B34side, the constricted portion45being formed to have the smallest path width in the first load transmission path P1(load transmission path) which connects together the vehicle-body fastening portion B34and the first battery fastening portion B42in the shortest length (seeFIG.4).

In the above configuration, in a side collision, the vicinity of the first battery fastening portion B42can certainly and easily be fractured, and a section to be fractured can easily be controlled.

As illustrated inFIG.3toFIG.5, as a form of a working example of the present disclosure, the rear-side bracket30L is configured to include the front-side flange33(flange portion) which is formed to bend with respect to the first load transmission path P1along an upper edge (at least one edge portion) of the first load transmission path P1in a path width direction (a direction orthogonal to the first load transmission path P1in a side view), and the front lower end33a(the end portion on the first battery fastening portion B42side) in the front-side flange33is configured to be positioned in the vicinity of the constricted portion45.

In the above configuration, because, in the first load transmission path P1, a rigidity difference is present between the vicinity of the first battery fastening portion P42and the other portions, in a side collision, the vicinity of the first battery fastening portion B42can certainly be fractured.

Further, durability (rigidity) against a vibration input from the first battery unit201, in usual traveling can be enhanced.

Consequently, achievement of both of certain fracture of the vicinity of the first battery fastening portion B42in a side collision and durability against a vibration input from the first battery unit201, in usual traveling can be intended.

The present disclosure is not limited only to the configurations of the above-described working examples but can be formed as various embodiments.

For example, a frame member is not limited to the rear side frame11as in the above-described embodiment as long as a rear portion of the battery unit20is capable of being mounted on the frame member via the rear-side bracket30L, and at least one of the side sill9and the floor frame10may be used, for example.

Further, a strength lowered portion of the present disclosure is not limited to formation as the constricted portion45as in the above-described embodiment, and a section in the first load transmission path P1which is formed to have the thinnest thickness, a section provided with a hole portion (a through hole or a non-through hole), or a configuration formed by combining at least two of those can be employed.

Further, in the above-described embodiment, the first battery unit20L on the left side of the vehicle1is provided with the inverter13as a high-voltage device; however, this is not restrictive, and a high-voltage device may be provided to the second battery unit20R on a right side of the vehicle1. In such a case, a fixing member (rear-side bracket30L) of the present disclosure can be provided to a right side of a vehicle.

Further, application of the present disclosure is not limited to a plug-in hybrid automobile (PHEV) as the vehicle1as long as a vehicle includes a motor and an engine, and application may be made to other vehicles such as a hybrid automobile (HV) and an electric automobile with a range extension function (range extender) (REEV), for example.