Batteries: thermoelectric and photoelectric – Thermoelectric – Adjuncts
Reexamination Certificate
1999-06-04
2001-09-25
Gorgos, Kathryn (Department: 1741)
Batteries: thermoelectric and photoelectric
Thermoelectric
Adjuncts
C136S203000, C062S003300
Reexamination Certificate
active
06294721
ABSTRACT:
BACKCGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system that uses thermoelectrics to control the ambient air temperature of an enclosure designed to house, protect and extend the useful life of batteries used in the telecommunications industry. Particularly, the temperature regulated enclosure is used to house hydrogen producing batteries which supply back up or supplemental power for telephone services in the event of commercial AC electric power failure.
2. Description of the Related Art
Telecommunications equipment, such as switches and repeaters, necessarily is placed in central and remote geographic locations in a network. Most of this telecommunications equipment is powered by alternating current (AC) supplied by electrical power lines. However, a backup power source is used to provide electrical power if an outage occurs on the AC power lines so that the equipment will remain operational. Hydrogen producing batteries are commonly used to provide this backup power. In some instances, these types of batteries are used for the primary source of electrical power.
Typically, batteries used in these environments are housed in protective enclosures designed to shield the batteries from vandalism, weather conditions and more particularly extremes in ambient temperatures. Unfortunately, these enclosures generally exacerbate the temperature conditions to which the batteries are subjected. It is well known by those within the commercial battery industry, that the effective life span of a battery is significantly diminished by extreme ambient temperatures.
It is well established that temperature is critical to battery longevity and many commercial battery manufacturers will only provide a warranty on the life of commercial batteries stored and used at temperatures not exceeding 77° F.+/−5° F. Some manufacturers even prorate or void warranties for batteries kept at higher temperatures based on a decrease of 50% of battery life for every 15 to 17° F. above the recommended 77° F. temperature which the battery is subjected to on a cumulative basis. High temperatures greatly accelerate the production of hydrogen gas from the batteries. Therefore, it is very desirable to control the ambient temperature within the storage enclosure housing telecommunication batteries.
It would be ideal to have a battery enclosure which is well insulated and unventilated for the batteries to facilitate ambient air temperature control within the enclosure. However, most batteries used in the telecommunications industry, in applications such as that described produce hydrogen gas. The buildup of hydrogen gas within a battery enclosure is dangerous and incidents of explosions resulting from hydrogen gas have been documented. It is common to vent battery enclosures used to house hydrogen batteries in order to prevent accumulation of hydrogen gas. Unfortunately, by venting the battery enclosure, it becomes increasingly difficult to maintain consistent temperatures within the enclosure, thereby diminishing the longevity of the batteries. A heat exchanger and a hydrogen vent system are desirable to safely facilitate long battery storage and use.
Controlling temperature within a battery storage compartment is achieved with the inventive device which utilizes the principles of thermoelectrics which have been known since the early 1800's when the Peltier effect was discovered. The Peltier effect is the resultant temperature change which occurs when electric current is passed through a selected material forming a junction between two conductors. With the introduction of semi-conductor materials, practical applications of this principle have flourished. Today, doped bismuth telluride is commonly used to create the n-type and p-type junction necessary for the temperature change to occur.
A typical device consists of p-type and n-type couples arranged electrically in series and thermally in parallel between two metalized ceramic plates. Heat moves from one side to the other creating a hot side and a cold side. By reversing the polarity between the conductors, the device can selectively provide either a cooling effect or a heating effect. Fan equipped heat exchangers then are placed in intimate contact with each of the distinct sides to facilitate the exchange of heat into the surrounding environment, comprising a system commonly referred to as a “heat pump.”
Known inventions utilize the Peltier effect to stabilize battery temperature rather than the ambient air temperature within a battery storage enclosure. One example of such a device may be found at U.S. Pat. No. 4,314,008 issued to Blake. The Blake device uses a Peltier type heat pump to manage battery temperature of rechargeable electrochemical cells by wrapping the battery in thermal insulation, such as a suitable thermally conductive “blanket”, which directly contacts the heat pump.
While the Blake device is suited to small cell type batteries it is not adaptable for use with large batteries, such as those used in the telecommunications industry. Encapsulating telecommunications-type batteries with any thermal “blanket” exacerbates problems of hydrogen accumulation within the battery enclosure. During the recharging phase, batteries generate hydrogen gas which can accumulate to explosive levels which may be exacerbated by a thermal blanket. Further, a battery insulating blanket such as that described and claimed by Blake would be unduly burdensome, would be too costly to manufacture and use, and would necessitate much work to substitute, add, or remove serially connected batteries.
What is needed is an environmental control system for a telecommunications battery system that incorporates a thermoelectric device into a remote standby battery storage enclosure such that ambient air temperature in the enclosure is reliably maintainable within selected parameters calculated to provide maximum remote battery life for telecommunication systems. Further, a device is needed which diminishes the problem of hydrogen gas buildup within the battery storage enclosure while allowing efficient maintenance of ambient air temperature within the enclosure. It is desirable to provide a device as described which may readily be retrofitted onto existing battery enclosures with minimal effort at a reasonable cost.
SUMMARY OF THE INVENTION
A new device is provided for controlling and maintaining the ambient air temperature within a remote telecommunications battery enclosure. The device includes a preferably modular housing enclosure of sufficient size to accommodate a predetermined number of commercial telecommunication batteries arranged for receiving power from an external power source, and at least one electrically powered thermoelectric device located in intimate contact with heat exchangers and fans configured such that at least one heat exchanger is positioned within or spaced in thermal communication with the interior of the battery enclosure, and at least one heat exchanger is positioned outside of or spaced in thermal communication with a thermal dissipation arrangement exterior to the battery enclosure.
The system further has a sensor and a microprocessor operably connected to the thermoelectric device configured to control the system to heat or cool the battery enclosure by responsively reversing polarity of the thermoelectric device as indicated by ambient air temperature or battery temperature to maintain the air temperature within predetermined limitations. The device will provide ventilation openings for the exchange of air between the environment and the battery enclosure. The provided vents will be designed to minimize condensation and evacuate accumulated hydrogen gas when present from within the enclosure with the vents of sufficient size and configuration to maintain sub Lower Explosive Limits (LEL) of hydrogen gas within the enclosure.
By applying the apparatus as described in the present invention, several advantages are realized. The battery enclosure may be insulated and sealed to control temperatures mo
Oravetz Thomas A.
Thompson Clyde J.
Gorgos Kathryn
Parsons Thomas H.
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