Battery module having battery guiding portions

1. A battery module comprising:

a battery group configured of a plurality of cylindrical batteries;

a holder configured to retain the battery group so that the plurality of cylindrical batteries are bundled in parallel to each other, respectively; and

a casing being closed by the holder and including a storing space for housing the battery group, wherein

the casing includes an opposing wall portion facing the holder,

the opposing wall portion includes hole portions that retain the plurality of cylindrical batteries by peripheries and/or inner circumferential surfaces of the hole portions, and guiding portions formed on the peripheries or the inner circumferential surfaces of the hole portions and configured to guide the plurality of cylindrical batteries during insertion into the storing space by causing the plurality of cylindrical batteries to come closer to centers of the hole portions, such that central axis lines of each of the plurality of cylindrical batteries pass through the centers of each of the hole portions, respectively,

the holder includes a plurality of retaining holes that each include an inner circumferential surface along which each of the plurality of cylindrical batteries, respectively, is inserted and which retains a peripheral surface of each of the plurality of cylindrical batteries,

the centers of the hole portions of the casing are positioned on central axis lines of the retaining holes, and

in each of the guiding portions, an outermost portion of the guiding portion is positioned farther on an outer side than a position that is separated by a distance of D·H/L on a radially outer side of the corresponding hole portion from a position of a straight line extending in a central axis line direction of the retaining holes and passing through an inner opening end of the corresponding retaining hole, where a difference between an opening diameter of the retaining hole and a diameter of a battery of the plurality of cylindrical batteries is denoted H, a length of the retaining hole in the central axis line direction is denoted L, and a distance between a straight perpendicular-line extending from the inner opening end of the retaining hole to a central axis line of the retaining hole and a straight perpendicular-line extending from the outermost portion of the guiding portion, which is a portion that is farthest away from the hole portion, to the central axis line of the retaining hole is denoted D.

2. The battery module according to claim 1 , wherein the guiding portions are tapered surfaces inclined radially inward toward an inserting direction of the plurality of cylindrical batteries.

3. The battery module according to claim 1 , wherein the guiding portions are surfaces of protrusions that protrude toward the storing space from the peripheries of the hole portions on the opposing wall portion.

4. The battery module according to claim 1 , further comprising

receiving surfaces for engaging ends of the plurality of batteries located farther on a radially inner side than the guiding portions, the receiving surfaces are provided on peripheries and/or inner circumferential surfaces of the hole portions.

5. The battery module according to claim 1 , wherein a bottom of the storing space of the casing is configured of the opposing wall portion.