Recombination device for storage batteries

A recombination device including a gas-tight enclosure connected to receive he discharge gases from a rechargeable storage battery. Catalytic material for the recombination of hydrogen and oxygen to form water is supported within the enclosure. The enclosure is sealed from the atmosphere by a liquid seal including two vertical chambers interconnected with an inverted U-shaped overflow tube. The first chamber is connected at its upper portion to the enclosure and the second chamber communicates at its upper portion with the atmosphere. If the pressure within the enclosure differs as overpressure or vacuum by more than the liquid level, the liquid is forced into one of the two chambers and the overpressure is vented or the vacuum is relieved. The recombination device also includes means for returning recombined liquid to the battery and for absorbing metal hydrides.

BACKGROUND OF THE INVENTION 
The present invention relates to a recombination device for use in 
conjunction with a storage battery for recombining hydrogen and oxygen 
gases discharged from the battery. It is particularly applicable to 
storage batteries and recombination devices that are to be enclosed in one 
gas tight housing or in two communicating housings with a pressure 
sensitive closure sealing against excess pressure or vacuum in respect to 
the outside atmosphere. 
The use of gas recombination devices with rechargeable storage batteries 
facilitates applying the topping or finishing charge to the battery. 
However, it has not been possible to use rechargeable storage batteries in 
the same way as gas-tight cells because the recombination devices are 
normally vented to the atmosphere. To prevent overpressure at high 
charging loads, the housing of the recombination device generally includes 
a small opening. Although this small opening presents a resistance to 
flow, a portion of the gases can escape from the recombination device. 
Water losses occur from non-stoichiometric gasing phases which produce 
surplus oxygen or hydrogen that are not catalytically recombined and from 
water vapor carried by the escaping gases. 
German patent publication DE-OS No. 28 04 583 shows the use of venting 
means in combination with a housing which contains a storage battery and a 
recombining device. The venting means is designed so that at a 
predetermined pressure in the housing, the vents open to permit escape or 
entry of gases depending on the pressure differential in respect to the 
outside atmosphere. Vents of this type may reduce water losses. However 
during extended use, the vents may not function properly due to corrosion 
or fatigue of the elastic materials. 
In view of these problems with prior devices, it is therefore an object of 
the invention to provide a pressure sensitive closure for a recombination 
device and storage battery which will permit the use under moderate 
operating conditions of a gas tight enclosure in conjunction with the 
storage battery. 
It is a further object to limit fluctuation of the gas equilibrium of a 
storage battery combined with a recombination device. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a device for catalytically 
recombing the discharge gases of a storage battery is presented in gas 
flow communication and in common gas-tight enclosure with the storage 
battery. The device is provided with a pressure sensitive closure 
employing a liquid-level seal to prevent excess pressure or vacuum within 
the gas-tight enclosure. 
In more specific aspects of the invention, the liquid-level seal includes 
two vertical partially liquid-filled chambers with an overflow tube 
communicating between the lower portions of the two chambers. One chamber 
is connected at is upper portion to the interior of the gas-tight 
enclosure and the other chamber has an opening in its upper portion to the 
atmosphere. 
In other aspects of the invention, the overflow tube is of inverted 
U-shaped with its ends positioned below the liquid level in the lower 
portions of the two chambers. 
The invention further contemplates means for preventing propagation of 
explosion by providing at least five centimeters of liquid level through 
which gases must vent from the gas-tight enclosure. 
In further aspects, an active carbon filter is included in the 
recombination device for absorbing metal hydrides.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the FIGURE, a gas recombination device 2 including a gas-tight enclosure 
2a is illustrated connected to a storage battery 1. A liquid lock or seal 
is shown as two vertical chambers 3, 4, which are partially filled with 
liquid. The chambers 3 and 4 are shown to communicate through a generally 
U-shaped overflow tube 5 with the inverted ends extending to the bottom 
portion of the chambers. The first chamber is connected at its upper end 
portion via tube 7 to the interior of gas-tight enclosure 2a of the 
recombination device 2. The second chamber is connected at its upper end 
portion to the atmosphere outside the gas-tight enclosure. The storage 
battery and recombination device are shown interconnected through a filter 
8 of active carbon through which the battery discharge gases flow. 
Other details shown in the drawing include a supplemental recombination 
catalyst 10 provided with a deflection plate 11. Supplemental catalyst 10 
will come into operation when the main recombination catalyst 9 is 
overloaded with gas flow. A gas conducting or distribution plate 12 
directs the gas flow from the storage battery 1 and active carbon filter 8 
into the channel formed between the main catalyst 9 and the supplemental 
catalyst 10. Water formed in the recombination device is returned to the 
battery through a return channel 13 connected to the storage battery via 
duct or conduit 14 and collars 15 and 16. Porous packing 17 and 18 are 
provided in the water return and gas flow channels. 
In the operation of the gas recombination device discharge gases from 
storage battery 1 enter through the porous packing 18 and the active 
carbon filter 8 where the metal hydrides are absorbed. The gas is directed 
by gas distribution plate 12 into the channel formed between sheets of 
catalytic material 9 and 10. It is at this point that gases such as 
hydrogen and oxygen are recombined to form water. In instances where there 
is an overload of gas flow, the excess will be diverted below catalytic 
material 10 and above distribution plate 12 to contact the active surface 
of catalytic material 10. Deflection plate 11 assists in directing the 
excess gas flow into contact with the catalyst. 
If an excess pressure occurs within the recombination device 2 it is 
communicated to closed chamber 4 through tubing 7. This forces the liquid 
from chamber 4 into chamber 3 through the overflow tube 5 until balance 
occurs. When the overpressure in the recombination chamber 2 is extreme, 
chamber 4 may be completely emptied and the resulting height of liquid in 
chamber 3 limits the excess pressure. 
Should a vacuum occur in the recombination device 2 the liquid will be 
drawn from chamber 3 into chamber 4 until a balance occurs. Should the 
amount of vacuum become so great as to force all of the liquid from 
chamber 3 into chamber 4 the resulting column of liquid in chamber 4 will 
limit the vacuum. 
During normal use of this storage battery and recombination device, the 
liquid lock or seal will provide a gas-tight and pressure controlled seal. 
Should liquid loss occur, recombination water may be used to refill either 
chamber 3 or 4 of the liquid seal. 
Since the liquid seal will permit the escape of gases both into and out of 
recombination device 2 when abnormal pressure differences occur, the seal 
functions as a safety pressure relief or vent. 
The liquid seal presented in accordance with the invention also provides 
protection against propagation of explosion. For this purpose, the column 
of liquid in the system through which escaping gas must pass should be at 
least 5 cm height. To further assist in this function, the overflow tube 5 
has a relatively low flow resistance and is arranged so that at least one 
of the chambers always contains liquid. 
The active carbon filter 8 is in the form of a bed of carbon particles 
which in combination with the liquid seal improves the security and life 
span of the storage battery. Poisonous gases such as stibine and arsine 
will be absorbed before coming into contact and poisoning the 
recombination catalysts. 
It is therefore seen that the present invention provides a liquid seal for 
use with a storage battery and recombination device in a common gas-tight 
enclosure. For instance the two may be in a single housing or in two 
communicating housings. The liquid seal prevents or limits escape of 
hydrogen or oxygen gases generated during non-stoichiometric operation. 
The moisture of the wet gases likewise is retained. The device also 
provides a vent or pressure relief when abnormally high pressure or vacuum 
occurs. Since the vent gases must always pass through a column of liquid 
an explosion prevention function is obtained. 
Although the present invention is described in terms of specific 
embodiments, materials, processes and techniques it will be clear to one 
skilled in the art that various modifications can be made in accordance 
with the invention as defined in the accompanying claims.