Note: Descriptions are shown in the official language in which they were submitted.
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IIighly porous separators are generally used in galvanic
elements to separate electrodes of different polarity. In lead
accumulators, these separators are usually wider and higher than
the corresponding electrode plates. The resulting overhang
should be as equal as possible on each side to prevent the
occurrence of short-circuits as a result of electrode growth o~
an outgrowth of conductive material. Instead of individual
separators, use is being made to an increasing extent of so-called
pockets made of an appropriate, preferably formable, material,
each pocket generally enclosing one plate of one of the two
types of electrodes and being open only at the top.
Such separators need no lateral projection beyond the
width of the electrodes in order to prevent short-circuiting.
However, the separator-pockets are generally made out of sections
of strip material which are folded in the vicinity of the lower
edge of the electrode and are welded laterally, for example by
heat or ultrasonics. As a result the lateral seams thus formed,
pro~ect beyond the width of the plate to the same extent as the
individual separators traditionally used.
The electrode separation which is achievable by means
of pockets disclosed in &erman Patent 2 330 134 reveals this
problem very clearly. This enclosing of the plates has the
disadvantage that the electrode does not occupy the full width
of the cell of the galvanic element. r~oreover, the fact that
separators and separator-pockets are wider than the electrodes
interferes with the correct alignment, transportation and
positioning of the block of plates necessary for the satisfactory
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assembly of the cell. These difficulties increase substantially
as the number of plates per element increases and as the thickness
of plates and separators decreases.
A separator which eliminates major projection of the
covering foil beyond the edges of the plate is disclosed in
German OS 2 45~ 824. In this case, the edges of the covering foil,
which project only slightly beyond the contour of the electrode,
are joined together by a flat, rigid strip and the edges of the
electrode are closed off as if by a smooth strip. However, since
this strip is applied in the form of an adhesive compound which
hardens only gradually, the production process is costly and time-
consuming.
It is therefore an object of the invention to provide
separation, especially for lead aeeumulators, whieh will allow
the eleetrode plates to make better use of the width of the eell
but does not make it difficult to install the stack of plates in
the cell, which also ensures reliable insulation of the lateral
edges of the plates, and the manufacturing process of which is
not detrimental to mass-production.
According to the invention, this object is achieved by
use of laterally projecting separator edge-strips which are bent
and cover at least the edge of each eleetrode.
It is partieularly advantageous for the separator
material used for the complete covering of the edges of the
eleetrodes to be a thermoplastic synthetic material, since this
allows the edge-strips to be welded or glued together.
However, aeeording to the invention, a less easily
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workable synthe-tic material may also be used for the separators.
Individual separators of this kind, made for example of hard
PVC, may be provided, with profiled strips of more easily formed
material, for example soft PVC, instead of projecting edge-strips.
~his anticipates the bending of the edge-strips which should be
bent over, if possible through more than 60, up to a maximum of
90, parallel with the sides of the electrodes.
In the case of separator-pockets, which may also be
used instead of individual separators and which contain a single
electrode plate of one polarity or the other, the material used
is naturally a thermoplastically formable material. In forming
these pockets, by welding the edges laterally, it is desirable
to carry out this procedure with a welding unit designed in such
a manner that the welded edges are simultaneously bent over as
far as possible.
In all of the above-mentioned cases, stacking the plates
with their separators produces an electrode assembly in which the
alignment from electrode to electrode is accommodated to a large
degree by the projecting edges of the interleaved separators.
Although the width of these edge-strips and the amount of the
original lateral projection, or of the weld seams in the case of
pockets, must be adapted to the relevant cell design and method
of assembly~ the edge-strips must at least cover the edges of
the electrode. All of the edge-strips overlap on each side like
louvres, and it is possible to press the raised edges of t:he
separator material, which is generally resilient, directly against
the edges of the p~ates or the lateral surface of the plate
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assembly. A stack of electrodes thus separated can be gripped~ transported
and positioned - either manually or, in particular, mechanically - without
sacrificing the alignment thereby avoiding the need for restoring alignment
through additional operational steps. According to the invention, this
advantage may be still further increased in that the edge-strips, pressed
laterally to the plate assembly, may be we'ded or glued together.
Depending upon the design of the cell~ care must be taken, under
certain circumstances and by means of assembly-aids or by means of an
additional folding over of the raised edges of the uppermost separator or
separator-pocket, to ensure that the latter do not interfere with the assembl-
ing of the battery if~ in the raised position~ they would increase the height
of the plate assembly beyond the available cell height.
In accordance with the present invention, there is provided an
electrical accumulator having a porous separator which insulates the plates
of an assembly of electrodes from each other and projects beyond the contour
of the said plates, characteri~ed in that the laterally projecting edge-strips
of the separator are bent through an angle of between 60 and 90 so that the
edge-strip covers at least the edge of each electrode.
The object of the invention is explained hereinafter in conjunction
with Figures 1 and 2 wherein:
Figure 1 illustrates ends of electrode plates mounted with
separators according to the present invention;
Figure 2(a) illustrates conventional separating devices;
Figure 2(b) illustrates ends of electrode plates mounted with
separators according to another embodiment of the present invention.
Figure 1 shows positive electrode plates 1 assembled into a stack
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with negative electrode plates 2 and intervening individual separators 4,
the edges 5 of which are bent through approximately 90 and are welded to-
gether. End-electrode 1 requires an additional fold 6 and an attachment 7.
The distance
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z between the container wall 8 and the ends of the plates 1 and
2 in the case of conventional separation corresponds to the width
of unbent edge 4, and thus used inefficiently. This distance
is reduced by the arrangement according to the invention to z'.
Figure 2(a) illustrates a conventional pocket-separation
9 in which the width s of the weld-seams, and an additional
tolerance and transition area ù, determine projection 5 and thus
distance z.
As shown in Figure 2(b), a reduced distance z' ls
obtained, according to the invention, by welding edge-projections
5 together and bending them in a single operation
