Structure for mounting batteries onto electric vehicles

A structure for mounting a battery onto an electric vehicle comprises: a body member forming a body of the electric vehicle; a battery case containing a battery; a supporting member, which is connected to the body member, fixed to a bottom of the battery case; and a clash-proof block connecting between the battery case and the body member.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a structure for mounting a battery onto an electric vehicle.

(2) Description of Related Art

Structures for mounting batteries onto electric vehicles have been known in the art. The following related document 1 discloses an example of such a structure.

In the related document 1, as shown in FIGS. 1-4, a battery box (30) is fixed to side frames (20a and 20b) by front fixing portions (56a) and rear fixing portions (56b).[Related Document 1] Japanese Laid-Open Publication H05-193369

However, by the technique of the related document 1, it is difficult to keep the battery box (30) in the correct position if a electric vehicle (10) is crashed.

For example, if a front end of the electric vehicle (10) is subject to impact, the battery box (30) moves forward due to inertia. Particularly, as the battery box (30) contains heavy batteries, the kinetic energy of the battery box (30) is considerable.

It is very difficult to keep the battery box (30) in the correct position by such a technique disclosed in the related document 1 whereby the front fixing portions (56a) and rear fixing portions (56b) fix the battery box (30) to the side frames (20a and 20b). Further, if the battery box (30) is fixed to the side frames (20a and 20b) by the structure shown in the related document 1, it is necessary to increase the size of the front and rear fixing portions (56a and 56b), and consequently, the weight and costs increase.

SUMMARY OF THE INVENTION

The present invention has been developed in consideration of this situation, and it is therefore an object of the invention to provide a structure for mounting a battery onto an electric vehicle to improve the crash-resistant capability of the battery mounted on the electric vehicle while preventing increased weight and cost.

For this purpose, in accordance with an aspect of the present invention, there is provided a structure for mounting the battery onto the electric vehicle comprising: a body member forming a body of the electric vehicle; a battery case containing a battery; a supporting member which is connected to the body member, fixed to a bottom of the battery case; and a clash-proof block connecting between the battery case and the body member.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIG. 1, side members (also called ‘body members’ or ‘first body members’)11and11are mounted on the left and right sides of an electric vehicle10. The side members11and11extend in the longitudinal direction of the electric vehicle10.

Further, a battery cross member (also called ‘body member’ or ‘second body member’)12, which extends in the transversal direction (left-right direction) and which connects the pair of side members11and11, is also mounted in the electric vehicle10.

The side members11and11and the battery cross member12are made of iron, and constitute a body of the electric vehicle10.

At a position between the pair of side members11and11and rear of the battery cross member12, a battery case13is disposed. The battery case13, which is made from polybutylene resin including glass fibers, contains and holds batteries20(shown inFIG. 4) inside thereof while avoiding ventilation between outside and inside by keeping the inside of battery case13airtight.

As shown inFIG. 2, the battery case13mainly comprises a battery tray14and a battery cover15.

As shown inFIG. 3, a front-end wall16, a left-end wall17, a right-end wall18, a rear-end wall19, a front partition21, a middle partition22and a rear partition23are fixed in the battery tray14.

The front partition21, the middle partition22and the rear partition23are walls extending between the left-end wall17and the right-end wall18in the left-right direction of the battery tray14.

The front partition21is disposed at the front of the middle partition22. The rear partition23is disposed at the rear of the middle partition22.

Further, in the battery tray14, front-battery partitions24A,24B,24C and24D are fixed. The front-battery partitions24A,24B,24C and24D are walls extending between the front-end wall16and the front partition21in the longitudinal direction (front-rear direction).

Furthermore, in the battery tray14, rear-battery partitions27A,27B,27C and27D are fixed. The rear-battery partitions27A,27B,27C and27D are walls extending between the rear-end wall19and the rear partition23in the front-rear direction.

Still further, in the battery tray14, front reinforcing walls25A and25B and concave side walls29and29are formed. The front reinforcing walls25A and25B are walls extending between the front partition21and the middle partition22in the front-rear direction. The concave side walls29and29are walls to individually make concave portions28A and28B.

Between the rear partition23and the middle partition22, middle-battery partitions26A and26B are formed which walls extend in the front-rear direction.

Further, between the middle-battery partitions26A and26B, rear reinforcing walls31A and31B are formed which walls extend in the front-rear direction.

As shown inFIG. 4, batteries20are fixed securely inside the battery case13in such a way that after the batteries20are individually disposed at the correct positions on the battery tray14, the batteries20are supported by battery holders (not shown), then the battery holders are fixed to the battery tray14by bolts (not shown).

As shown inFIG. 5, in the battery tray14, a frame set (also called ‘metal frame’)32is included. The frame set32, which is made from iron, mainly comprises front frame set33and rear frame set34.

The front-left frame38is an L-shaped part. On a left surface of the front-left frame38, nuts38A,38B,38C and38D are welded. Further, on a front surface of the front-left frame38, a nut38E is welded. The front-left frame38is embedded in the left-end wall17and the front-end wall16of the battery tray14shown inFIG. 3.

Likewise, the front-right frame37shown inFIG. 5is an L-shaped part. On a right surface of the front-right frame37, nuts (not shown) are welded. Further, on a front surface of the front-right frame37, a nut37E is welded. The front-right frame37is embedded in the right-end wall18and the front-end wall16of the battery tray14as shown inFIG. 3.

The front-middle frame36shown inFIG. 5is a U-shaped part. On the front surface of the front-middle frame36, two nuts36A and36B are welded.

Additional plates39A and39B, which are parts of the front-middle frame36, extend in the front-rear direction. The additional plate39A is embedded in the front-battery partition24A, which is disposed between imaginary lines L1and L2and extends rearward from a front block (also called ‘first clash-proof block’)63A shown inFIG. 3. Likewise, the other additional plate39B is embedded in the front-battery partition24D, which is disposed between imaginary lines L3and L4extending rearward from another front block (also called ‘first clash-proof block’)63B. A front wall36C, which is a part of the front-middle frame36, extends in the left-right direction. The front wall36C is embedded in the front-end wall16. Into the nuts38A,38B,38C,38D,38E and37E, bolts67are fitted.

The rear-lateral-left frame41is a part embedded in the left-end wall17shown inFIG. 3. On a left surface of the rear-lateral-left frame41, nuts41A,41B,41C and41D are welded.

The iron built-in nut51comprises an upper nut52, a middle stem53and a lower nut54.

The upper nut52is a cylindrical part which extends in the vertical direction and has an upper opening52A which opens upwardly. Inside the upper nut52, a bolt groove52B is formed.

The lower nut54is identical to the upper nut52except that the upper nut52is in an upside-down position. In other words, the lower nut54is also a cylindrical part which extends in the vertical direction and has a lower opening54A which opens downwardly. Inside the lower nut54, a bolt groove54B is formed.

The middle stem53is a cylindrical part between the upper nut52and the lower nut54. On the surface of the middle stem53, a plurality of notches (serrated portion)53A are formed.

Between the upper nut52and the middle stem53, an upper constriction55A is formed. Also, between the middle stem53and the lower nut54, a lower constriction55B is formed.

The upper constriction55A and the lower constriction55B are cylindrical parts whose outer diameter (second diameter) D2is smaller than the outer diameter (first diameter) D1of the upper nut52, the lower nut54and the middle stem53.

Because of the serrated portion53A formed on the middle stem53, it is possible to avoid loosening and spinning of the built-in nut51embedded in the battery tray14even if a rotational torque is inputted to the built-in nut51around the center axis C51.

Further, according to the upper constriction55A and the lower constriction55B, it is possible to avoid the built-in nut51dropping from the battery tray14even if the force is inputted to the built-in nut51along the direction of the center axis C51.

As shown inFIG. 8andFIG. 9, lateral-end supporting members (also called ‘supporting members’ or ‘first supporting members’)61A,61B,61C and61D are fixed to the bottom surface14A of the battery tray14.

The lateral-end supporting member61A is disposed at the front row called an A-supporting member61A. The lateral-end supporting member61B disposed rear of the A-supporting member61A is called a B-supporting member61B.

Further, the lateral-end supporting member61C disposed rear of the B-supporting member61B is called a C-supporting member61C. Likewise, the lateral-end supporting member61D disposed rear of the C-supporting member61C is called a D-supporting member61D.

As shown inFIG. 1, each of the lateral-end supporting members61A,61B,61C and61D extends in the transversal direction connecting between the side members11and11to support the bottom surface14A. The lateral-end supporting members61A,61B,61C and61D are made from iron.

As shown inFIG. 8, on the A-supporting member61A, front-end supporting members (also called ‘supporting members’ and ‘second supporting members’)62A and62B are fixed. Each of the front-end supporting members61A and62B is a part which extends in the longitudinal direction of the vehicle10and is projected forward from the front end of battery tray14.

As shown inFIG. 10, the front-end supporting members62A and62B are only connected to the A-supporting member61A and are not connected to the B-supporting member61B, C-supporting member61C and D-supporting member61D (see ‘X’ inFIG. 10).

As shown inFIG. 1, the front-end supporting members62A and62B connect between the battery cross member12and A-supporting member61A via front blocks63A and63B which will be described just below. In addition, the front-end supporting members62A and62B are made from iron.

On the front-end supporting members62A and62B, each of the front blocks (also called ‘clash-proof blocks’ or ‘first clash-proof blocks’)63A and63B is welded respectively. The front blocks63A and63B are fixed to the front-end wall16by bolts64(shown inFIG. 8) and are fixed to the battery cross member12by bolts65(shown inFIG. 1).

In other words, the front blocks63A and63B are parts which individually connect between the battery cross member12and the A-supporting member61A and are disposed between the battery cross member12and the battery tray14. Further, the front blocks63A and63B are made from iron.

As shown inFIG. 1, second clash-proof blocks (also called “clash-proof blocks’ or ‘second clash-proof blocks’)66A,66B,66C and66D are respectively welded on both ends of each of the lateral-end supporting members61A,61B,61C and61D.

The lateral clash-proof block66A fixed on the A-supporting member61A is called an A-lateral clash-proof block66A. The lateral clash-proof block66B fixed on the B-supporting member61B is called a B-lateral clash-proof block66B. The lateral clash-proof block66C fixed on the C-supporting member61C is called a C-lateral clash-proof block66C. The lateral clash-proof block66D fixed on the D-supporting member61D is called a D-lateral clash-proof block66D.

As shown inFIG. 8, the lateral clash-proof blocks66A,66B,66C and66D are fixed to the left-end wall17and the right-end wall18of the battery tray14by bolts67, and are fixed to the side members11and11by bolts68as shown inFIG. 1.

As shown inFIG. 2, the lateral clash-proof blocks66A,66B,66C and66D, which connect between side member11and the battery case13, are respectively disposed between the bottom surface of the side member11and the lateral-end supporting members61A,61B,61C and61D. Each of the lateral clash-proof blocks66A,66B,66C and66D is made from iron and is a hollow square pillar in shape.

Further, each of the A-lateral clash-proof block66A and the B-lateral clash-proof block66B is directly fixed to the side member11, whereas, as shown inFIG. 2, the C-lateral clash-proof block66C is fixed to the side member11via a C-connecting block69C. Also, the D-lateral clash-proof block66D is fixed to the side member11via a D-connecting block69D.

Although the side member11is extended from a point (shown as an arrow A inFIG. 2) backwardly and upwardly, the battery tray14is kept in a horizontal position because the C-connecting block69C is interposed between the side member11and the C-supporting member61C, also the D-connecting block69D is interposed between side member11and the D-supporting member61D.

As shown inFIG. 11, the A-supporting member61A is fixed by the bolt68engaged with a cap nut11B mounted in the reinforcing member11A of the side member11. The B-supporting member61B is also fixed to the side member11by the structure shown inFIG. 11, description of which is omitted in the drawings.

As shown inFIG. 12, the C-supporting member61C is connected to the side member11via the C-connecting block69C. The C-connecting block69C is a hollow iron part in which a cap nut11C is mounted. The C-supporting member61C is fixed to the C-connecting block69C by the bolt68engaged with the cap nut11C

As shown inFIG. 13, the D-supporting member61D is connected to the side member11via the D-connecting block69D. The D-connecting block69D is a hollow iron part. The D-supporting member61D is fixed to the side member11by the bolt68engaged with the cap nut11D mounted in the side member11.

Further, a nut69D1is welded on the bottom of the D-connecting block69D. The D-supporting member61D is fixed to the D-connecting block69D by a bolt71which engages with the nut69D1.

As shown inFIG. 9, between the left-end wall17of the battery tray14and the side member11and between the right-end wall18of the battery tray14and the side member11, two high-voltage cables72are respectively disposed. The high-voltage cables72, which are capable of carrying about 300V, connect between the batteries20mounted in the battery case13and an inverter (also called ‘external device) not shown in the drawings.

Each of the high-voltage cables72has a hole connector73connected to an electric-output socket (not shown) in the battery case13.

At both the lateral surface of the battery tray14facing the side members11(namely, at the left-end wall17and the right-end wall18) and the bottom surface14A of the battery tray14, dent portions28A and28B are formed.

Each of the dent portions28A and28B has a concave side wall29, which extends parallel to the side member11, a concave front wall74, which extends from the front end of the concave side wall29in the lateral direction, and a concave rear wall75, which extends from the rear end of the concave side wall29in the lateral direction.

Further, as shown inFIG. 14, casing bolt-hole portions76, a casing low-voltage cable hole portion77, a casing center-hole portion78and a casing high-voltage cable hole portion (cable hole portion)79are formed at the concave side wall29.

A cover plate81shown inFIG. 15is fixed on the back surface of the concave side wall29. Cover plate81will be described below in detail.

Each of the casing bolt-hole portions76shown inFIG. 14is a hole through which a plate fixing bolt (not shown) is engaged with a plate bolt-hole portion82formed on the cover plate81.

Low-voltage cables89(shown inFIG. 16) used for supplying about 12V electric power to electrical equipment pass through the casing low-voltage cable hole portion77. Further, the casing low-voltage cable hole portion77communicates with a plate low-voltage cable hole portion83.

The casing center hole portion78communicates with a venting hole84formed at the cover plate81.

High-voltage cable72(shown inFIG. 9) passes through each of the casing high-voltage cable hole portions79and79. The casing high-voltage cable hole portions79and79respectively communicate with plate high-voltage cable hole portions85A and85B formed at the cover plate81.

Further, each concave side wall29is kept at a distance L5(shown inFIG. 9) defined based on the outer diameter D3of the high-voltage cable72from the side member11.

The greater the outer diameter D3(thickness) of the high-voltage cable72, the greater distance L5between the concave side wall29and the side member11becomes to permit bending of cable72. Conversely, the smaller outer diameter D3, the shorter distance L5may be.

As shown inFIG. 15, the cover plate81is fixed to the back surface of concave side wall29of the battery tray14. The cover plate81is a plate made from aluminum covering the casing bolt-hole portions76, the casing low-voltage cable hole portion77, the casing center hole portion78and the casing high-voltage cable hole portions79as discussed with reference toFIG. 14.

Aluminum is used for cover plate81because both rigidity and weight saving are required, and it is also necessary to avoid detachment between the cover plate81and battery tray14even if the resin material of battery tray14expands or contracts due to temperature variation.

One point the inventors have focused attention on is that the linear expansion coefficients of the main material of the battery tray14which is polybutylene resin including glass fiber and the material of the cover plate81which is aluminum, are almost the same, and accordingly, the cover plate81is made from aluminum.

At the cover plate81, the plate bolt-hole portions82, the plate low-voltage cable hole portion83, the venting hole84and the plate high-voltage hole portions (cable hole portions)85A and85B are formed.

Each of the plate bolt-hole portions82is a hole in which each of the plate fixing bolts104shown inFIG. 17are engaged.

The plate bolt-hole portions82open to the front side (near side inFIG. 15) of the cover plate81. However, the plate bolt-hole portions82do not open to the back (far side inFIG. 15) of the cover plate81. Consequently, the cover plate81is not penetrated by the plate bolt-hole portions82.

In the plate low-voltage cable hole portion83, as shown inFIG. 16, a rubber cap88is fitted. The low-voltage cables89are inserted through the rubber cap88.

The venting hole84is a hole for venting air from the battery case13when the air pressure increases in the battery case13. In venting hole84, a one-way valve (not shown) is fitted, thereby maintaining airtightness in the battery case13.

As shown inFIG. 15andFIG. 18, each of the plate high-voltage cable hole portions85A and85B is a hole into which individual socket ends101A and101A of cable holders101and101are inserted. The plate high-voltage cable hole portions85A and85B are respectively communicated with the casing high-voltage cable hole portions79and79shown inFIG. 14.

Into the cable holders101and101, each of the high-voltage cables72and72is individually inserted. Each of the socket ends101A and101A of the cable holders101and101has a rubber O-shaped ring103individually equipped to secure airtightness in the battery case13.

The cable holders101and101are fixed to the cover plate81by holder fixing bolts102and102, respectively. The holder fixing bolts102and102are bolts which are individually engaged with cable holder hole portions86A and86B.

The cable holder hole portions86A and86B are holes which are respectively formed adjacent to the plate high-voltage cable hole portions85A and85B. The cable holder hole portions86A and86B open to the front side of the cover plate81and do not open to the back side of the cover plate81.

The inner surface of each of the plate high-voltage cable hole portions85A and85B is mirror finished so that the O-shaped ring103fits each of the plate high-voltage cable hole portions85A and85B without leaving a gap.

Further, because of the mirror finished inner surface, it is possible to protect the O-shaped ring103from any damage when the O-shaped ring103is inserted into each of the plate high-voltage cable hole portions85A and85B.

Additionally, a sealing groove87is formed around the outer edge of the cover plate81. Sealing agent (not shown) is filled into sealing groove87avoid to leaving a gap between the concave side wall29of the battery tray14and the cover plate81as shown inFIG. 17.

As shown inFIG. 19andFIG. 20, the battery cover13has a front raised portion91, a middle raised portion92and a rear raised portion93.

The front raised portion91is a portion which is raised near the front end of the battery cover13. The rear raised portion93is a portion which is raised near the rear end of the battery cover13. On the front raised portion91, a maintenance hole portion94is formed.

The maintenance hole portion94is formed for maintaining inside the battery case13and is normally covered by a covering plate (not shown).

The middle raised portion92is a portion which is raised between the front raised portion91and the rear raised portion93, however, the middle raised portion92is lower than the front raised portion91and the rear raised portion93in height.

A flange95, on which cover bolt hole portions96are formed, is formed around the edge of the battery cover13.

As shown inFIG. 3, tray bolt hole portions105, corresponding to the location of the cover bolt hole portions96, are formed on the front-end wall16, the left-end wall17, right-end wall18, and rear-end wall19of the battery tray14(namely, around the edge of battery tray14).

According to this arrangement, the cover bolt hole portions96and the tray bolt hole portions105respectively communicate with each other when the battery cover15is put on the battery tray14. Thus, it is allowed that bolts (not shown) are individually inserted into the cover bolt hole portions96and the tray bolt hole portions105to fix the battery tray14and the battery cover15.

Namely, the embodiment of the present invention can provide the following effects or/and advantages.

For example, if the front side of the electric vehicle10is crashed, the battery case13containing batteries20moves forward due to inertia. Particularly, the batteries20are comparatively heavy, therefore, it is impossible to omit kinetic energy of the battery case13when the electric vehicle10is crashed.

However, according to the present invention in this embodiment, it is possible to avoid the battery case13moving forward and being crashed against the battery cross member12because the lateral-end supporting members61A,61B,61C and61D and the front-end supporting members62A and62B are provided.

Namely, it is possible to maintain the gap (see GFinFIG. 1) between the battery case13and the battery cross member12even if the electric vehicle10is crashed, and therefore, it is possible to avoid damage to cables (not shown) installed in the gap GFso that the reliability of the electric vehicle10is improved.

The front-end supporting members62A and62B are not connected to all of the lateral-end supporting members61A,61B,61C and61D, however, the front-end supporting members62A and62B are connected to only the lateral-end supporting member61A which is disposed at the front row. Accordingly, it is possible to reduce the length of the front-end supporting members62A and62B, and therefore, it is possible to suppress the weight and cost of front-end supporting members62A and62B.

Namely, it is possible to improve crash-resisting capability of the batteries20mounted on the electric vehicle10while preventing increased weight and cost.

Further, the lateral-end supporting members61A,61B,61C and61D and front-end supporting members62A and62B are made from iron. In addition, the battery case13is made from polybutylene resin including glass fibers. According to this arrangement, it is possible to reduce the weight of the battery case13at a reasonably low cost in mass production. Further, it is also possible to improve the mounting stiffness of the battery case13in relation to the electric vehicle10.

The battery case13containing the batteries20is robustly supported by the lateral-end supporting members61A,61B,61C and61D, and further, the front blocks63A and63B prevent collision of the battery case13with the battery cross member12if the battery case13moves forward due to inertia even if the front side of the vehicle10is crashed.

Further, the lateral clash-proof blocks66A,66B,66C and66D are inserted between the side surface of the battery case13and the side member11, and accordingly, it is possible to avoid a collision of the battery case13with the side member11if the battery case13moves laterally due to inertia even if the lateral side of the vehicle10is crashed.

Namely, it is possible to keep the gap (see GSand GSinFIG. 1) between the battery case13and the side members11even if the electric vehicle10is crashed, therefore, it is possible to prevent damage of the high-voltage cables72and low-voltage cables89installed in the gap GSand GSso that the reliability of the electric vehicle10is improved.

Additionally, the lateral-end supporting members61A,61B,61C and61D and front-end supporting members62A and62B and battery cross member12are made from iron. Further, the battery case13is made from polybutylene resin including glass fibers.

According to this arrangement, it is possible to reduce the weight of the battery case13at a reasonably low cost in mass production. Further, it is also possible to improve the mounting rigidity of the battery case13on the electric vehicle10.

The front-end supporting members62A and62B and the battery cross member12are connected via the front blocks63A and63B. Further, the lateral-end supporting members61A,61B,61C and61D and the side members11are connected via the lateral clash-proof blocks66A,66B,66C and66D. According to this arrangement, it is possible to lower the center of gravity of the battery case13containing the heavy batteries20.

Further, due to inserting the front blocks63A and63B between the battery case13and the battery cross member12and inserting the lateral-end supporting members61A,61B,61C and61D between the battery case13and the side members11, it is possible to avoid collisions between the cross member12or the side member11if the battery case13moves due to inertia even if the vehicle10is crashed.

Therefore, it is possible to improve the crash-resistant capability of the batteries20mounted on the electric vehicle10.

Namely, if the front side of the electric vehicle10is crashed, it is possible to avoid collision with the battery cross member12if the battery case13moves forward due to inertia. Likewise, if the lateral side of the electric vehicle10is crashed, it is possible to avoid collision with the side members11if the battery case13moves laterally due to inertia.

As discussed previously withFIG. 9, the high-voltage cables72and72are individually inserted into the plate high-voltage cable hole portions85A and85B formed at the cover plates81respectively fixed on the dent portions28A and28B of the battery case13. Further, the high-voltage cables72and72, which are disposed between the side members11and the battery case13, are curved in an arc shape with a bending radius.

Further, each of the concave side walls29of the dent portions28A and28B is distanced L5, which is defined corresponding to the outer diameter D3of the high-voltage cable72, from the side member11. Accordingly, it is possible to avoid damaging the high-voltage cables72due to bending the high-voltage cables72with excessively small radius and it is also possible to avoid wasting the space in the battery case13due to curving the high-voltage cables72with excessively large radius.

In other words, it is possible to easily install the high-voltage cables72connected to the batteries20mounted on the electric vehicle10while utilizing limited space in the electric vehicle10

Further, the high-voltage cables72are connected to the batteries20via the hole connectors73, and accordingly, it is possible to secure the connection between the high-voltage cables72and the batteries20at a lower cost.

Particularly, it is possible to avoid unwanted disconnection of the high-voltage cables72from the batteries20in the battery case13due to using the hole connectors73to connect between the batteries20and the high cables72as compared with using conventional detachable connectors.

Therefore, it is possible to improve the reliability of the electric vehicle10by preventing accidental disconnection between the high-voltage cables72and the batteries20.

Further, it is possible to reduce cost and weight of the electric vehicle10by using the hole connectors73as compared with using conventional detachable connectors.

Each of the high-voltage cables72is drawn from inside the battery case13through the plate high-voltage cable hole portions85A and85B formed at the aluminum cover plate81, and accordingly, it is possible to avoid excessively varying the inner diameter of the plate high-voltage cable hole portions85A and85B due to variation of air temperature.

Further, it is possible to avoid external air flowing into the battery case13due to sealing by each O-shaped ring103between the outer surface of the high-voltage cables72and72and the inner surface of the plate high-voltage cable hole portions85A and85B.

Additionally, although the plate bolt-hole portions82open to the front side of the cover plate81, the plate bolt-hole portions82do not open to the back side of the cover plate81, and accordingly, it is possible to secure the airtightness in the battery case13while allowing the plate fixing bolts104, for fixing the cover plate81to the battery case13, to be engaged with the plate bolt-hole portions82.

As shown inFIG. 6andFIG. 7, portions whose outer diameter is locally small (second diameter D2) at the built-in nut51, namely, the upper constriction55A and the lower constriction55B in which resin of battery tray14is entered. Accordingly, it is possible to avoid the built-in nut51dropping from the battery tray14even if force is vertically inputted to the built-in nut51.

Further, due to the serrated portion53A formed on the middle stem53, it is possible to avoid spinning of the built-in nut51embedded in the battery tray14even if torque is inputted to the built-in nut51to rotate the built-in nut51around the center axis C51, accordingly, it is possible to surely engage the bolt (not shown) with the built-in nut51.

From the present invention is not limited to the above embodiment, but covers all changes and modifications which do not constitute departures from the spirit and scope of the invention.

In the embodiment, as shown inFIG. 21, the A-supporting member61A, which supports the bottom of the battery case13, is connected to the A-lateral clash-proof block66A (see A4inFIG. 21). Further, the A-lateral clash-proof block66A is connected to the side member11(see A2inFIG. 21). Still further, the A-lateral clash-proof block66A is also connected to the battery case13(see A3inFIG. 21).

However, the present invention is not limited to this embodiment. For example, as shown inFIG. 22, in addition to the structure shown inFIG. 21, the A-supporting member61A may be connected directly to the side member11(see A1inFIG. 22).

According to this arrangement, it is possible to further improve the crash-resisting capability of the batteries.

Additionally, as shown inFIG. 23, the A-supporting member61A may be connected directly to the side member11(see A1inFIG. 22) and not be connected to the A-lateral clash-proof block66A. Accordingly, it is possible to define the position of the A-lateral clash-proof block66A irrespective of the position of the A-supporting member61A.