Chemistry: electrical current producing apparatus – product – and – Having specified venting – feeding or circulation structure – Venting structure
Reexamination Certificate
1999-01-18
2001-07-03
Chaney, Carol (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Having specified venting, feeding or circulation structure
Venting structure
C429S087000, C429S161000
Reexamination Certificate
active
06255014
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electric storage batteries, and more particularly to an arrangement for venting gases from thin metal film battery cells.
Thin metal film (TMF) battery technology provides a compact high power battery cell. Cells of this type are well known and their construction and manufacture have been described in, for example, U. S. Pat. Nos. 3,494,800; 5,045,086; 5,047,300; 5,198,313 and 5,368,961 the disclosures of which are hereby incorporated by reference. A thin metal film battery cell includes thin metal film plates sealed within a valve-regulated, sealed cell container. The cells include absorptive glass-mat (AGM) separator technology in an electrolyte starved system. The thin metal film plates are made from very thin lead film pasted on both surfaces with an active material. Plates having positive active material and plates having negative active material are spiral wound with separator material, and terminations are cast-on or soldered to the ends of the spiral roll. The roll is encapsulated in a container which is filled with electrolyte and then sealed.
When thin metal film batteries are charged, the excitation of the positive and negative active materials tends to heat the electrolytic fluid which causes some of the electrolytic fluid to change from a liquid to a gas. This gas accumulates and increases the pressure within the battery case. In extreme overcharging conditions, the accumulated gas can rupture the battery enclosure. Prior art inventions place openings in the battery enclosure to release the gas and prevent built-up pressure within the enclosure; however, the electrolyte may also exit through such openings. Thus, the present invention is directed to the venting of gases accumulated in a thin metal film battery housing while preventing electrolyte from exiting the housing.
SUMMARY OF THE INVENTION
In accordance with the invention, the apparatus includes a battery housing containing at least one cavity for holding a battery cell. The housing is enclosed by a cover having a vent opening at the base of a venting well that is substantially centered and recessed within one end of the cavity so as to substantially fill the top of the cavity. The venting well also includes a pipe, or well aperture, at its center extending outwardly from the vent opening. A baffle is disposed at an inner end of the well aperture that partially interrupts direct flow through the vent opening.
Preferably, a flexible valve cap is mounted on the top of, and seals to, the well aperture. The valve cap is preferably made of a flexible rubber material that expands at a venting pressure to allow gases from within the cavities to escape and contracts when below the venting pressure to reseal to the well aperture. A well lid or cover closes the top of the well.
Such a vent arrangement is provided above each cell in a multiple cell battery. The vent may be formed in a top that closes the body into which the cells are mounted. Preferably, the top is interchangeable with a bottom that does not include the vents.
The foregoing and other objects and advantages of the invention will be found in the detailed description that follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.
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Andrew Michael G.
Dougherty Thomas J.
Lenz James A.
Chaney Carol
Johnson Controls Technology Company
Quarles & Brady LLP
Tsang Susy
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