GB1571473A - Accumulator battery - Google Patents

Description

(54) ACCUMULATOR BATTERY (71) We, ELBAK BATTERIEWERKE GESELLSCHAFT m.b.H., an Austrian Company, of Puntigamer Strasse 127, Graz-Puntigam, (Steiermark), Austria, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an accumulator battery comprising a plurality of cells having plastic boxes, which are inserted in a battery case and covers mounted on the top edge of the boxes and joined thereto by butt welding.

Such batteries. which are referred to as traction batteries, are used, e.g., in fork lift trucks and similar vehicles and have the advantage that the cells can be used in such a number and such a circuit arrangement that a battery having the desired capacity and voltage is obtained. It has been disclosed, e.g., in Printed German Application 1,910,352 and Opened German Specification 2,145,216 to join the covers to the plastic boxes of the cells of such batteries by butt welding. The butt-welded joints between the covers and boxes are absolutely acid-tight and such batteries can be manufactured much more simply than the previous welded batteries which have covers that are fitted into the box and then welded. Besides. the need for a potting compound for sealing each cell of the battery has been eliminated.

A difficulty arising in batteries of the kind mentioned first hereinbefore resides in that acid can enter between the cells of the battery and between the cells and the battery case when the battery is being recharged or serviced and even when the battery is being filled.

The presence of such acid results in a premature destruction of the battery case whereas the moisture permits of undesired leakage currents.

It is an object of the invention to provide an accumulator battery which is of the kind mentioned first hereinbefore and is free from the above-mentioned disadvantages and nevertheless can easily be manufactured. This is accomplished in accordance with the invention in that the side edges of the covers are bevelled or rounded and the grooves thus formed at the edges of the covers between adjacent cells and between the cover and the wall of the battery case are cast up with a potting compound.

Within the scope of the invention, the grooves are preferably cast up with asphalt or with a potting compound consisting of plastics material.

In an accumulator battery designed in accordance with the invention, acid and other impurities cannot enter between the several cells of the battery and between the cells of the battery and the battery case in which they are inserted.

Further details of the invention will become apparent from the subsequent description of a preferred illustrative embodiment shown on the accompanying drawing, in which Figure 1 is a partly sectional view showing a portion of an accumulator battery and Figure 2 is a top plan view showing the battery of Figure 1 when the grooves have not yet been cast up.

A battery case 1 of steel contains a plurality of cells 2 in a number and circuit arrangement which depend on the desired voltage and capacity. Each cell 2 comprises a box 3 and a cover 4, which is mounted on the top edge of the box 3 and connected to it by an acid tight butt-welded seam 5. The box 3 and the cover 4 consist preferably of plastics material, such as polypropylene. As is usual, the cells 2 comprise plates 7, which are secured to the cover 4 by plate straps 8. Those ends of the plate straps 8 which protrude above the cover 4 are connected by strap connectors 9 in accordance with the desired circuit diagram. The arrangement is such that the plate straps 8 and, if desired, the plates 7 connected thereto are permanently connected to the cover during the manufacture of the latter. This can be accomplished, e.g., in that material for the cover is injection-moulded around the plate straps and, if desired, the plates. The cover 4 has a filling opening for acid or distilled water. This opening can be sealed by a screw plug.

As has been shown in Figure 1, the side edges 6 of the covers 4 have bevelled surfaces which face upwardly so that open-topped grooves 11 are formed between adjacent cells 2 and between the covers 4 and the battery case 1. This is particularly well apparent from Figure 2. These grooves 11 are filled with a potting compound 12. Suitable potting compounds 12 are the conventional asphalt potting compounds as well as any potting compound of a plastics material which is compatible with the material of the cells 2.

The side edges of the covers may alternatively be rounded so that the resulting grooves are defined by convex and/or concave surfaces. The edges need not be bevelled throughout the thickness of the covers.

WHAT WE CLAIM 1. An accumulator battery comprising a plurality of cells having plastic boxes, which are inserted in a battery case, and covers mounted on the top edge of the box and joined thereto by butt welding, characterized in that the side edges of the covers are bevelled or rounded and the grooves thus formed at the edges of the covers between adjacent cells and between the cover and the wall of the battery case are filled with potting compound.

2. An accumulator battery as claimed in claim 1, characterized in that the grooves are filled with asphalt or with a potting compound of plastics material.

3. An accumulator battery as claimed in claim 1 or 2, characterized in that the grooves are open-topped and defined by upwardly facing, bevelled or rounded surfaces of the side edges of the covers.

4. An accumulator battery substantially as described hereinbefore with reference to or as shown on the accompanying drawing.

5. An accumulator cell for use in a battery case, said cell comprising a box of plastics material and a cover mounted on the top edge of the boxes and Joined hereto by butt-welding, characterized in that the side edges of the cover are bevelled or rounded and are adapted to define grooves with an edge of the cover of an adjacent cell in such battery case and with a wall of such battery case.

6. An accumulator cell as claimed in claim 5, characterized in that said side edges of the covers have upwardly facing, bevelled br rounded surfaces.

7. An accumulator cell, substantially as described hereinbefore with reference to or as shown on the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. above the cover 4 are connected by strap connectors 9 in accordance with the desired circuit diagram. The arrangement is such that the plate straps 8 and, if desired, the plates 7 connected thereto are permanently connected to the cover during the manufacture of the latter. This can be accomplished, e.g., in that material for the cover is injection-moulded around the plate straps and, if desired, the plates. The cover 4 has a filling opening for acid or distilled water. This opening can be sealed by a screw plug. As has been shown in Figure 1, the side edges 6 of the covers 4 have bevelled surfaces which face upwardly so that open-topped grooves 11 are formed between adjacent cells 2 and between the covers 4 and the battery case 1. This is particularly well apparent from Figure 2. These grooves 11 are filled with a potting compound 12. Suitable potting compounds 12 are the conventional asphalt potting compounds as well as any potting compound of a plastics material which is compatible with the material of the cells 2. The side edges of the covers may alternatively be rounded so that the resulting grooves are defined by convex and/or concave surfaces. The edges need not be bevelled throughout the thickness of the covers. WHAT WE CLAIM

1. An accumulator battery comprising a plurality of cells having plastic boxes, which are inserted in a battery case, and covers mounted on the top edge of the box and joined thereto by butt welding, characterized in that the side edges of the covers are bevelled or rounded and the grooves thus formed at the edges of the covers between adjacent cells and between the cover and the wall of the battery case are filled with potting compound.

2. An accumulator battery as claimed in claim 1, characterized in that the grooves are filled with asphalt or with a potting compound of plastics material.

3. An accumulator battery as claimed in claim 1 or 2, characterized in that the grooves are open-topped and defined by upwardly facing, bevelled or rounded surfaces of the side edges of the covers.

4. An accumulator battery substantially as described hereinbefore with reference to or as shown on the accompanying drawing.

5. An accumulator cell for use in a battery case, said cell comprising a box of plastics material and a cover mounted on the top edge of the boxes and Joined hereto by butt-welding, characterized in that the side edges of the cover are bevelled or rounded and are adapted to define grooves with an edge of the cover of an adjacent cell in such battery case and with a wall of such battery case.

6. An accumulator cell as claimed in claim 5, characterized in that said side edges of the covers have upwardly facing, bevelled br rounded surfaces.

7. An accumulator cell, substantially as described hereinbefore with reference to or as shown on the accompanying drawings.