Chemistry: electrical current producing apparatus – product – and – With control means responsive to battery condition sensing... – Temperature control
Patent
1992-11-12
1994-06-28
Kalafut, Stephen
Chemistry: electrical current producing apparatus, product, and
With control means responsive to battery condition sensing...
Temperature control
429120, H01M 1050
Patent
active
053245970
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a thermal shunt for a battery, in particular, a battery which must be thermally insulated to retain heat, such as a battery made up of cells having a solid electrolyte and electrodes of molten materials.
A typical example of such a cell is a sodium sulphur cell which will employ liquid sodium as the anode and liquid sulphur as the cathode, the two being separated by a solid electrolyte of beta alumina which is electronically insulating but conductive to cations of the alkali metal.
A battery will comprise several of the cells connected together within a thermally-insulated container or battery box. Because the electrochemical reaction will only proceed efficiently at elevated temperatures, the typical operating temperature is about 350.degree. C.
During charging and discharging of the cells, heat is generated due to internal resistances, for example, and builds up within the battery box. Although some of this internal heat energy is offset to some extent by the slow natural cooling of the battery, this cooling is not sufficient to keep the temperature at the desired operating value, especially in cases where the insulation of the battery box is particularly efficient or the duty particularly arduous.
Since increases in temperature are undesirable and if allowed to proceed too far will lead to overheating of the battery which could result in damage, ways have been considered of providing means whereby heat is allowed to be conducted out through the insulating battery container.
Accordingly, the present invention provides a thermal shunt for a battery contained in a thermally-insulating container comprising an external heat sink and means, connected between the heat sink and the battery, which at a predetermined temperature are actuated to conduct heat from the battery to the heat sink, thereby increasing the heat loss from the battery.
Preferably, the means connecting the heat sink to the battery is a thermally conductive fluid which makes thermal contact with both the battery and heat sink only when the predetermined temperature is reached.
Preferably, the thermal shunt further comprises a pump which at the predetermined temperature urges the thermally conductive fluid to make a thermal contact between one or more selected points on the battery surface and heat sink.
Preferably, the pump supplies fluid to one or more containers connected between the battery and the heat sink.
Preferably, the containers are bellows.
Preferably, the thermal shunt is arranged on the lower surface of the battery.
In a second embodiment of the present invention the thermal shunt further comprises a pump which supplies pressurised gas or vapour to one or more containers holding the thermally conductive fluid.
Preferably, the container or containers for the fluid is a concentric bellows arrangement, the gas or vapour being delivered to the bellows arrangement to urge the fluid to make thermal contact between the battery and the heat sink.
Preferably, the gas or vapour is delivered to the inner bellows and the fluid is urged between the inner and outer bellows to make thermal contact between the battery and heat sink.
Preferably, the thermal shunt is arranged on the upper surface of the battery.
In a third embodiment of the present invention the means connecting the battery to the heat sink is one or more partially filled containers of liquid located between the heat sink and battery, the liquid being maintained at a given pressure such that it will boil at the predetermined temperature to release vapour which will condense in the vicinity of the heat sink to effect heat conduction from the battery to the heat sink.
Preferably, the liquid is mercury pressurised to substantially 1.034.times.10.sup.5 Nm.sup.2 which will boil at substantially 350.degree. C.
Preferably, the thermal shunt is arranged on the upper surface of the battery.
Preferred embodiments of the present invention will now be described in detail, by way of example only, with reference to the accompanying drawings of which:
FIG. 1 is a s
REFERENCES:
patent: 3837918 (1974-09-01), Nakabayashi
patent: 3865630 (1975-02-01), Reimers
patent: 4042757 (1977-08-01), Jones
patent: 4138692 (1979-02-01), Meeker et al.
patent: 4207386 (1980-06-01), Meinhold
patent: 4314008 (1982-02-01), Blake
patent: 4329407 (1982-05-01), Gross et al.
patent: 4376809 (1983-03-01), Bindin
patent: 4443525 (1984-04-01), Hasenauer
patent: 4517263 (1985-05-01), Reiss et al.
Leadbetter Alan
Mangan Michael F.
Molyneux John
Kalafut Stephen
Silent Power GmbH fur Energiespeichertechnik
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