Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
2000-03-28
2003-06-03
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S175000, C523S134000
Reexamination Certificate
active
06572999
ABSTRACT:
The finding concerns a container especially suited for electric “recombination” type batteries but not solely limited to these.
It is known that “recombination” batteries are special batteries where the electrolyte cannot be identified as a liquid separated from the other components making up the battery cells, but is a substance that impregnates a basically spongy material called a “separator” which is in close contact with a metal “matrix”.
The chemical interaction between separator, made of suitable material and impregnated with electrolyte, and metal matrix, allow the passage of electric current.
Each battery cell consists of an alternating sequence of separators and matrices in close contact with each other.
Since the electrolyte is not liquid but rather impregnated in the separator, it is evident that the close contact between separator and matrix is an essential condition for achieving the ion exchange and subsequent “recombination” that gives rise to the rejoining of the original molecule and releasing of energy that is the basis of the battery's operation. As a consequence, to make sure that separators and matrices do not come apart, current technology houses each cell in a space enclosed by rigid walls suited to resisting even the internal pressure surges that may develop during the electrochemical reactions. The most common types of containers for recombination batteries essentially comprise an open case, with a basically parallelepiped form, and a cover hermetically coupled to the case along the outer rim and holding the battery terminals.
With the aforesaid scope of supporting internal surges in pressure, the inside volume of the battery case is partitioned by a series of rigid baffles, set vertically and parallel to one another, defining a sequence of chambers each of which designated to receive a battery cell.
What's more, current technology prescribes that the case containing the battery cells and the cover connected to it are constructed in high quality plastic, such as ABS, in order to guarantee an adequate rigidity and therefore a considerable resistance to deformation.
An additional inconvenience in known containers per recombination batteries is related to the transmission of heat out of the container. This heat transmission is particularly critical through the side faces of the case.
Normal kinds of acid batteries, such as for example automobile starter batteries, have containers made from moulded polypropylene. Although even these kinds of batteries have the problem of deformation in the walls, above all in the walls parallel to the baffles separating the various chambers. This problem is even more marked in batteries that are wider than average and with their walls parallel to the baffles being larger. In order to prevent too great a deformation, current technology prescribes the use of thicker polypropylene than required under normal conditions, with thicknesses even reaching up to 5 mm.
This finding intends to remedy the aforementioned inconveniences. Therefore the intention is to produce a container for batteries that has greater rigidity properties, with equal thickness, than known containers.
More specifically, concerning recombination batteries made of ABS, the intention is to produce a container made from moulded polypropylene with the addition of an appropriate reinforcement so that the rigidity properties of ABS are maintained.
On the other hand, with regards to batteries already produced in polypropylene, the intention is to limit deformation of containers to a minimum while still producing a container in polypropylene with sufficient reinforcement to increase its rigidity.
Another intended scope is to produce containers for normal or recombination type batteries that, even though they have greater material performances, maintain a low cost and ease of manufacture.
An additional scope of the finding is to increase the degree of efficiency in dissipating the heat produced internally by the battery cells.
All the aforementioned scopes and others that will be better explained below are achieved by a container for batteries that, in accordance with the contents of the main claim, comprises an open, prism-shaped case with its inside having a series of vertical baffles suited to creating chambers for the cells of said battery and having a watertight cover coupled to it, which holds the battery terminals, said container being characterised in that at least the case of said container is made from moulded polypropylene bonding mica in granular powder.
According to a preferred form of execution of the finding the mica bonding is made from crystals with particle sizes that vary from 0,5 to 100 &mgr;m.
An advantage of the finding is that the plastic-bonded mica, which is an Aluminium compound, significantly increases the case's rigidity preventing deformation of the walls parallel to the baffles, them being the weakest walls since they are not sustained by the baffles, as occurs in the opposite walls. Another advantage that is obtained from the use of plastic-bonded mica is excellent heat conductivity because the mica is a mixture of more or less complex aluminium compounds which, being finely dispersed throughout the polypropylene because of the fine particle size used, achieves excellent heat exchange taking the heat developed by the recombination battery from inside to outside the actual battery, which is essential to guaranteeing its good longterm operation.
With the material under this finding both cases and covers of the batteries can be moulded and all this can be done with the wall thickness being little more than normal batteries, but still keeping a clear cost advantage over the use of ABS.
It should also be said that the use of polypropylene-bonded mica, against ABS, simplifies the moulding operations since the same moulds suited to moulding batteries in normal polypropylene can be used, while containers in ABS for known types of recombination batteries require moulds of different technology to polypropylene injection. This is because ABS is a much more viscous material and therefore the equipment has to be adapted to this special material.
A variant in execution of the finding prescribes that the rigidity of polypropylene-bonded mica is combined with a special configuration of the walls parallel to the baffles of the battery case, making a series of protruding ribbing in these walls suited to reinforcing said case to counteract the pressure inside the actual container.
An advantage of this variant is that the protruding ribbing is set on the outside of said case and is preferably spaced apart and intersecting thereby defining a grid construction.
Other ways of producing the protruding ribbing prescribe forming a honeycomb type construction on the outside surfaces of the case with polygon-shaped pockets.
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Alejandro R
Dykema Gossett PLLC
Kalafut Stephen
LandOfFree
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