Battery venting system

Abstract

A battery venting system that is useful for cordless power tools. The system can include a cell that may have a sleeve with a plurality of apertures surrounding a peripheral side face of the cell to enhance heat dissipation from the cell. A plurality of cells may be electrically connected to form a cell pack. A carrier includes an upper carrier and a lower carrier to sandwich a plurality of cells that are aligned parallel to each other. The carriers include at least one vent hole that are aligned with a gap formed from adjacent cells to define an elongated fluid flow path. A charger may be provided to receive a housing containing the carrier and may be provided with a fan to direct a flow into the fluid flow path.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates generally to a battery venting system that is useful for cordless power tools. The system includes one or more of battery cells, sleeves that may surround the battery cell, a carrier that can position and hold a number of battery cells to form a cell pack, and a charger useful with the battery cells and / or carrier. [0002] Rechargeable nickel-cadmium cells and nickel-metal hydride cells are widely used as a battery power source for portable apparatus, such as power tools. Typically, nickel-cadmium cells or nickel-metal hydride cells are used in the form of a cylindrical cell that has a cylindrical shape. In the portable apparatus, the cylindrical cells are used alone or more typically in the form of a cell pack in which a plurality of cells are connected and are contained within a housing that can be removably attached to an apparatus. [0003]FIG. 1 shows a typical cylindrical cell, which has a cylindrical case 1 that co...

AI Technical Summary

Benefits of technology

[0010] In yet another aspect of the present invention, a carrier of a plurality of battery cells is provided to arrange and hold the plurality of battery cells to define a cell pack. The carrier may be used with battery cells without an outer case, with battery cells having an outer case, or with battery cells having electrically non-conductive sleeves according to the present invention. In one embodiment, the carrier causes the terminals on each end of the cells to be positioned in a substantially same plane.

[0013] According to the present invention, a plurality of battery cells are held between the pair of upper and lower carriers and heat generated from the cells can be dissipated via the elongated fluid flow path. Since the outward-directed peripheral side faces of the battery cells may be free of electrically insulating material and are exposed to the exterior between the pair of upper and lower carriers, heat can also be dissipated from the peripheral side faces of each battery cell. Alternatively, if a sleeve according to the present invention is provided, i.e., with a plurality of apertures, a substantial portion the peripheral side faces of the battery cells will be exposed to the exterior between the pair of upper and lower carriers so that heat can be dissipated from the peripheral side faces of each battery cell.

[0014] The venting effect can be further enhanced by forcing a fluid such as air past and through the cell pack. For example, in another aspect of the present invention, a charger is provided with a fan to force a fluid into the cell pack where it can pass through adjacent cells. Advantageously, the charger may be configured to provide charging of more than a single cell pack, either sequentially or simultaneously. The charger is provided with a mechanism to simultaneously force fluid into two separate cell, while charging.

Problems solved by technology

A disadvantage to providing an electrically insulating case around each cell is that when a plurality of cells are provided to form a cell pack, heat generated upon discharge and upon recharging operations is not easily dissipated.

When the temperature of the cell is raised as a result of the heat generation, self-discharge may reduce the cell capacity or shorten the service life of the cell.

Although this solution may be useful, the plates take up space within the battery pack housing and by virtue of their size still hinder heat dissipation.

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