Battery unit mounting structure of electric vehicle

1. A battery unit mounting structure of an electric vehicle, comprising:

a floor panel;

a pair of right-and-left floor frames provided below the floor panel, each of which forms a closed-cross section extending longitudinally cooperatively with the floor panel; and

a battery unit supporting plural battery modules and mounted at the pair of floor frames,

wherein said battery unit comprises a pair of right-and-left side frames attached to said pair of floor frames, a cross frame extending in a vehicle width direction and interconnecting said pair of side frames, and the plural battery modules,

said plural battery modules are respectively formed in a rectangular shape in a plan view and have substantially the same size comprising a longitudinal dimension which corresponds to a longitudinal direction of said rectangular shape, a lateral dimension which corresponds to a direction perpendicular to said longitudinal direction of the rectangular shape, and a height dimension which corresponds to a vehicle vertical direction perpendicular to said longitudinal direction and said direction perpendicular to the longitudinal direction of the rectangular shape,

said plural battery modules are respectively mounted at said side frames and/or said cross frame in the same position and arranged in plural rows adjacently to the vehicle width direction and/or a vehicle longitudinal direction such that the direction of said longitudinal dimension of the rectangular shape is substantially parallel to the vehicle longitudinal direction or the vehicle width direction, and

mounting rigidity of the battery modules positioned at a part of said plural rows is set to be different from that of the battery modules positioned at another part of said plural rows.

2. The battery unit mounting structure of the electric vehicle of claim 1 , wherein said plural battery modules are arranged in three or more rows extending in the vehicle width direction, and the mounting rigidity of the battery modules positioned at any one-end-side row of said three or more rows is set to be different from that of the battery modules positioned at the other row of said three or more rows.

3. The battery unit mounting structure of the electric vehicle of claim 2 , wherein said plural battery modules are arranged in the longitudinal direction in three or more rows, the battery modules positioned at a foremost row of said three or more rows are arranged in a single-layer state and the battery modules positioned at a rearmost row of said three or more rows are arranged below a kick-up portion of said floor panel in a two-layer state of upper-and-lower two stages, and the mounting rigidity of said battery modules positioned at the foremost row is set to be different from that of the battery modules positioned at the other row.

4. The battery unit mounting structure of the electric vehicle of claim 3 , wherein said plural battery modules are mounted at said side frames and/or said cross frame by mounting brackets.

5. The battery unit mounting structure of the electric vehicle of claim 4 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

6. The battery unit mounting structure of the electric vehicle of claim 4 , wherein the number of mounting points of said mounting brackets to mount the battery modules positioned at the part of the plural rows is set to be larger than the number of mounting points of said mounting brackets to mount the battery modules positioned at the other part of the plural rows.

7. The battery unit mounting structure of the electric vehicle of claim 3 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

8. The battery unit mounting structure of the electric vehicle of claim 2 , wherein said plural battery modules are arranged in the longitudinal direction in three or more rows, the battery modules positioned at a foremost row and a second row behind the foremost row of said three or more rows are arranged in a single-layer state and the battery modules positioned at another row behind said second row are arranged in the two-layer state of the upper-and-lower two stages, and the mounting rigidity of said battery modules positioned at the foremost row is set to be different from that of said battery modules positioned at the second row.

9. The battery unit mounting structure of the electric vehicle of claim 8 , wherein said plural battery modules are mounted at said side frames and/or said cross frame by mounting brackets.

10. The battery unit mounting structure of the electric vehicle of claim 9 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

11. The battery unit mounting structure of the electric vehicle of claim 9 , wherein the number of mounting points of said mounting brackets to mount the battery modules positioned at the part of the plural rows is set to be larger than the number of mounting points of said mounting brackets to mount the battery modules positioned at the other part of the plural rows.

12. The battery unit mounting structure of the electric vehicle of claim 8 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

13. The battery unit mounting structure of the electric vehicle of claim 2 , wherein said plural battery modules are mounted at said side frames and/or said cross frame by mounting brackets.

14. The battery unit mounting structure of the electric vehicle of claim 13 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

15. The battery unit mounting structure of the electric vehicle of claim 13 , wherein the number of mounting points of said mounting brackets to mount the battery modules positioned at the part of the plural rows is set to be larger than the number of mounting points of said mounting brackets to mount the battery modules positioned at the other part of the plural rows.

16. The battery unit mounting structure of the electric vehicle of claim 2 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

17. The battery unit mounting structure of the electric vehicle of claim 1 , wherein said plural battery modules are mounted at said side frames and/or said cross frame by mounting brackets.

18. The battery unit mounting structure of the electric vehicle of claim 17 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.

19. The battery unit mounting structure of the electric vehicle of claim 17 , wherein the number of mounting points of said mounting brackets to mount the battery modules positioned at the part of the plural rows is set to be larger than the number of mounting points of said mounting brackets to mount the battery modules positioned at the other part of the plural rows.

20. The battery unit mounting structure of the electric vehicle of claim 1 , wherein said mounting rigidity of the battery modules positioned at the part of the plural rows is set to be higher than said mounting rigidity of the battery modules positioned at the other part of the plural rows.