Battery pack enclosure with vent
Vented cells are held in a cell holder, which is also vented, to provide an escape path for gases that may be produced by failing or overloaded cells. The escape path leads to the outside of the cell holder, which is mounted in an enclosure forming the battery pack. The enclosure is also vented, via a pressure-relief valve, which allows for the escape of hot cell gases to the surrounding air. A cell holder is made up of a top tray, an intermediate tray and a frame. A venting path is formed between the top and intermediate trays.
1 . A battery pack comprising:
a plurality of cells, each cell having at least one vent;
a cell holder in which the cells are held;
at least one vent in the cell holder that provides a venting path from the vents in the cells to outside of the cell holder; and
an enclosure within which the cell holder is installed, the enclosure having a pressure-relief valve;
wherein the enclosure and the cell holder define another venting path, from the outside of the cell holder to the pressure-relief valve.
2 . The battery pack of claim 1 , wherein the cell holder is made with heat-resistant, fiber-reinforced plastic.
3 . The battery pack of claim 1 , wherein the cell holder is made using polycarbonate/acrylonitrile-butadiene-styrene.
4 . The battery pack of claim 1 , wherein the cell holder comprises:
a frame that hosts the cells such that a portion of each cell projects beyond a top of the frame;
an intermediate tray on top of the frame and having recesses each of which accommodate one of said portions of the cells; and
a top tray on top of the intermediate tray and fastened to the frame through the intermediate tray.
5 . The battery pack of claim 4 , comprising, in each recess, one or more protrusions on a wall of the recess to maintain the cell that is accommodated by the recess centered in the recess.
6 . The battery pack of claim 4 , wherein the frame defines a cavity for each cell that it hosts.
7 . The battery pack of claim 6 , wherein the recesses in the intermediate tray are aligned with the cavities in the frame.
8 . The battery pack of claim 7 , wherein each recess has a smaller diameter than the corresponding cavity.
9 . The battery pack of claim 6 , comprising, in each cavity, one or more protrusions on a wall of the cavity to maintain the cell that is in the cavity centered in the cavity.
10 . The battery pack of claim 6 , wherein each cavity has a ledge at a bottom section thereof that supports the cell in the cavity.
11 . The battery pack of claim 10 , wherein each cavity is open to a bottom of the frame.
12 . The battery pack of claim 11 , comprising a cooled plate that is glued to bottom surfaces of the cells when the cells are in the cell holder.
13 . The battery pack of claim 4 , wherein:
the top tray comprises studs each with a snap lock at its extremity;
the intermediate tray defines holes through each of which one of the studs passes; and
the frame defines further holes each with a retaining surface to which one of the snap locks engage.
14 . The battery pack of claim 13 , wherein each retaining surface is a step in a wall of one of the further holes.
15 . The battery pack of claim 13 , wherein a ratio of snap locks to cells is between 1:1 and 10:1.
16 . The battery pack of claim 13 , wherein the snap locks are irreversible.
17 . The battery pack of claim 13 , wherein the snap locks are reversible.
18 . The battery pack of claim 4 , comprising a negative busbar in the top tray and a positive busbar in the intermediate tray.
19 . The battery pack of claim 4 , comprising locating features in the frame and the intermediate tray that engage with each other.
20 . The battery pack of claim 4 , wherein the intermediate tray, the top tray, or both the intermediate and top trays define the venting path.