Strap for battery module, battery module comprising same, and jig for compressing strap
Disclosed is a strap, which compresses an outer surface of a battery module to prevent the battery module from being deformed by swelling of a battery cell, and the strap has a closed loop structure larger than an outer peripheral of the battery module, and at least a portion of the strap is folded at the closed loop to provide a welding portion at which the folded portions overlap each other when a predetermined compression is applied thereto.
1 . A battery module, comprising:
a cell assembly having a plurality of battery cells and a cell stacking frame;
an end plate configured to encircle the cell assembly, the end plate having a tubular shape with four wall portions and two open ends;
at least three metal straps surrounding the end plate, each strap being a single-body, integrally formed endless closed loop structure that is larger than an outer peripheral of the battery module, each strap including a first strap region, a second strap region, a third strap region and a fourth strap region, which are provided to surround a lower surface, a left surface, a right surface and an upper surface of the battery module, respectively; and
two sensing assemblies located at the two open ends of the end plate,
wherein the end plate includes at least three grooves corresponding to the at least three metal straps, the at least three grooves including a centrally located groove and two grooves located at the two open ends of the end plate,
wherein, prior to welding, a maximum length of the first strap region is less than a maximum length of the fourth strap region,
wherein at least a portion of each strap is folded in the fourth region to provide a welding portion at which folded portions overlap such that outer surfaces of each strap at the welding portion directly contact each other when a predetermined compression is applied thereto,
wherein, prior to folding the at least the portion of each strap, the fourth strap region further includes a horizontal region extending horizontally with respect to a ground on the basis of the welding portion and an inclined region extending with a slope with respect to the ground,
wherein the welding portion is welded,
wherein, when the inclined region is pressed, the second strap region is deformed integrally with the inclined region,
wherein, prior to folding the at least the portion of each strap, the second strap region is connected to the inclined region while forming an obtuse angle with respect to the ground, and the third strap region is perpendicular with respect to the ground, and
wherein none of the at least three metal straps extend across the two open ends of the end plate.
2 . The battery module according to claim 1 , wherein the welding portion is folded in a zigzag pattern.
3 . The battery module according to claim 1 , wherein the folded portions for each strap overlap in a vertical direction relative to the ground.
4 . The battery module according to claim 1 , wherein the end plate includes a base plate and a cover plate having a u-shape.