JPH0531206A - Fire detector in sodium-sulfur battery - Google Patents

Abstract

PURPOSE:To extinguish the fire of the batteries in a case in an early period and to prevent the burn of the normal batteries by the spreading fire by detecting the fire of the batteries in the case in an early period. CONSTITUTION:A discharge pipe 10 which discharges the gas in the case 1 housing the integrated batteries 5 consisting of the sodium-sulfur batteries to the outside is provided through the side wall of the case and a temp. sensor 12 for fire detection is disposed in a part of a flow passage to this discharge pipe 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detection device in a sodium-sulfur battery, and more specifically, when an abnormality occurs in the sodium-sulfur battery and a chemical reaction between active materials of an anode and a cathode inside the battery causes The present invention relates to a fire detection device that detects a fire that has occurred.

[0002]

2. Description of the Related Art In recent years, research and development of a sodium-sulfur battery which operates at a temperature of about 300 ° C. has been promoted as a secondary battery for electric vehicles and nighttime power storage. This sodium-sulfur battery is a large number of single cells assembled and housed in a case, and has excellent characteristics in both performance and economy,
In terms of performance, it has a higher theoretical energy density than lead-acid batteries, has no side effects such as the generation of hydrogen and oxygen during charge and discharge, and has a high utilization rate of the bipolar active material. Further, in terms of economy, it has an advantage that sodium metal and sulfur are inexpensive.

And, this sodium-sulfur battery has about 3
By heating to 00 ° C., metallic sodium and sulfur as active materials are melted, and ions of the active materials are moved in the molten state to cause electrochemical reaction with each other to obtain predetermined electric energy. ing.

[0004]

However, in this type of sodium-sulfur battery, if an overcurrent such as an accidental short circuit current flows, the solid electrolyte tube inside the battery may be destroyed. At the time of this destruction, the molten metal sodium and molten sulfur, which are divided into the inside and outside by the solid electrolyte tube, come into direct contact with each other, and they are mixed with each other to cause a chemical reaction. Then, the reaction heat destroys the cover of the battery itself, which causes a problem of fire in the case. This fire may spread in a chain from abnormal cells that first triggered the fire to normal cells, and it is necessary to detect it immediately and activate the fire extinguisher.

Since the above-mentioned abnormality of the unit cell starts from a very small number of hundreds of unit cells, even if the electrical change of the output voltage, current, etc. is observed from the outside, the change becomes clear. Since it does not appear, it is difficult to realize a fire detection device based on this electric signal.

There is also a device for sucking the air in the case and detecting an internal abnormality depending on the presence or absence of a component of sulfur dioxide contained therein, but even if a small amount of sulfur leaks from a single battery that does not cause a fire. Since it reacts, there is a problem that it is not reliable as a device for detecting a fire.

[0007] Further, there is a device which is regarded as a fire when a temperature sensor made of a thermocouple is placed inside the case and a temperature obviously higher than the operating temperature (300 ° C) is detected. The temperature of the cell itself is measured by making close contact with the side surface of the cell at a typical position, and the temperature sensor can detect the fire of cells other than this cell only after the fire spreads considerably. Become. Although it is possible to attach all temperature sensors to a large number of single cells, the feasibility is extremely low in terms of manufacturing and cost.

The present invention has been made by paying attention to the problems existing in such a conventional technique, and the purpose thereof is to detect the fire of the battery in the case at an early stage so as to make an initial extinction. It is an object of the present invention to provide a fire detection device for a sodium-sulfur battery that can realize the above and prevent the normal battery from being burnt.

[0009]

In order to achieve the above object, according to the present invention, a vent pipe is provided on a side wall of a case accommodating an assembled battery of sodium-sulfur batteries, the vent pipe penetrating the inside and outside of the case. The temperature sensor for fire detection is arranged in the gas pipe or a part of the gas flow path passing through the gas pipe.

[0010]

[Operation] In the sodium-sulfur battery configured as above, when an abnormal reaction occurs in the sodium-sulfur battery and a fire occurs in the case, the temperature in the case rises and Since the internal pressure rises due to the gas generated by the reaction with, the gas inside the case and the generated gas flow toward the vent pipe and are discharged from the vent pipe to the outside of the case. At this time, the temperature of the heated gas is detected by a temperature sensor arranged in the ventilation pipe or a part of the gas passage passing through the ventilation pipe, and the detection signal from this temperature sensor is discriminated. Detected in.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment embodying the present invention will be described below with reference to the drawings. As shown in FIG. 1, case 1
Is formed in a rectangular box shape and has a double wall structure of inner and outer walls, and a heat insulating material 2 is disposed between the inner and outer walls. A mounting table 4 is disposed inside the case 1 via a support member 3. A large number of unit cells 5 are erected on the mounting table 4. Although not shown, each unit cell 5 may house a single sodium-sulfur battery or a plurality of single sodium-sulfur batteries that are vertically stacked and connected in series, or one unit. It may be a battery.

[0012] The single sodium-sulfur battery separately stores metallic sodium and sulfur via a solid electrolyte tube. An electric heater 6 is installed between the bottom of the case 1 and the mounting table 4 to keep the temperature in the case 1 at about 3 degrees.
By heating to 00 ° C., metallic sodium and sulfur in the unit cell 5 are melted.

A ventilation pipe 10 is attached to an upper part of one side of the case 1 so as to penetrate the inside and outside of the case 1, and a cap 11 is fitted to the outer end thereof. This ventilation pipe 10
The cap 11 may be opened at all times, but the cap 11 is opened or detached even when the pressure in the case 1 slightly rises.

On the inner wall surface of the case 1, a temperature sensor 12 for detecting a fire of the unit cell 5 is located in a gas passage passing through the ventilation pipe 10 in close proximity to the internal opening 10a of the ventilation pipe 10. Is supported by a bracket 13. Further, a discriminating circuit 15 for discriminating that a fire has occurred in the case when the temperature detected by the temperature sensor 12 becomes equal to or higher than a set temperature is connected to the temperature sensor 12 via a lead wire 14. ..

When the inside of the case 1 is maintained at about 300 ° C., the metallic sodium and sulfur of the sodium-sulfur battery constituting the unit cell 5 is in a molten state. Here, if the solid electrolyte tube of the sodium-sulfur battery that constitutes the unit cell 5 is damaged for some reason, the molten metal sodium in the solid electrolyte tube directly contacts and mixes with the molten sulfur. Then, the following chemical reaction is performed as a main reaction to produce sodium polysulfide, and finally, sodium trisulfide.

At this time, a large amount of heat of chemical reaction is generated, the case of the unit cell 5 itself is thermally destroyed, and metallic sodium and sulfur flow into the case 1. Then, metallic sodium not only reacts with sulfur, but also the product and unreacted sodium and sulfur further react with oxygen in the air to reach a high temperature state, which causes not only thermal expansion of internal gas but also generation of high temperature. Due to the pressure increase due to the gas, the cap 11 of the ventilation pipe 10 is detached from the inside of the case 1, and the internal gas is released to the outside. This outflow operation is usually continued by vigorous reaction for 20 to 60 seconds or more. Since the flow path of the high-temperature generated gas is a single flow path, the gas flow surely touches the temperature sensor 12 arranged near the inlet of the ventilation pipe 10, and the accident battery is stored in the case 1. Temperature sensor 12 that can detect temperature rise due to the accident
Only possible.

This detection signal is transmitted to the discriminating circuit 15 via the lead wire 14, and this circuit discriminates whether or not the detection signal exceeds the set value. When the detected signal exceeds the set value, it means that a fire has occurred. Is determined, and accordingly, a display device and an alarm device (not shown) are activated.

By the way, when sodium or sulfur alone flows out, they react only with oxygen in the air and do not undergo a violent reaction such as between sodium and sulfur. Since the cap 11 is not opened and no air flow is generated, there is a possibility that the occurrence of fire cannot be detected. However, there is almost no fear that such a state will spread to the adjacent healthy assembled battery 5, and even if the abnormality cannot be detected, there is no particular problem.
Such an abnormality is caused by the SO placed near the temperature sensor 12.
It is detected by _two sensors (not shown). It is possible to detect the occurrence of a fire that spreads to the adjacent healthy unit cells 5 by the detection signals of both the SO ₂ sensor and the temperature sensor 12. In the case of this combined use method, the unit cell does not cause a fire, and even if the temperature inside the case 1 is abnormally heated due to an external factor, it is not considered as a fire, so the reliability of fire detection should be improved. Will be possible.

[0019]

Another Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the change rate of the temperature signal input from the temperature sensor 12 to the temperature change rate determination circuit 21 is determined, and when the change rate is larger than the set change rate, it is determined that a fire has occurred in Case 1. It was done. In this embodiment, the fire can be discriminated earlier than in the above embodiments.

Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the case 1
An injection nozzle 9 for injecting the extinguishant S together with the inert gas G into the case 1 is connected to the left upper side wall of the. Further, the case 1 is an exhaust pipe serving as a ventilation pipe for discharging the inert gas G in the case 1 at a position separated from the injection nozzle 9 so as to be at the same height position as the injection port 9a of the injection nozzle 9. The pipe 10 is connected. This exhaust pipe 1
A cap 11 for suppressing heat loss (heat release) inside the case is fitted to the outer end portion of 0. The exhaust pipe 10 may be opened at all times, but the cap 11 is detached even when the pressure in the case 1 slightly rises.
The sensor 1 is arranged so as to be located in a gas passage passing through the exhaust pipe 10 in close proximity to the internal opening 10a of the exhaust port 10.
2 is provided.

The extinguishant supply device 16 is operated by the discriminating circuit 15, and the inert gas G and the extinguishant S are supplied according to the operation signal from the discriminating circuit 15. The types of the inert gas G are helium, neon, argon gas,
Nitrogen gas is suitable. Further, ceramic particles are used as the fire extinguishing agent S.

Now, when the temperature sensor 12 detects a fire, the discrimination circuit 15 is operated and the extinguishant supply device 1 is operated.
6 is operated, and the ceramic grains S are supplied into the case 1 by the injection nozzle 9 together with the inert gas G. The ceramic particles S first fly horizontally in the space R and collide with the inner surface of the right side wall of the case 1, and then enter between the unit cells 5 by their own weight. Further, the ceramic grains S are sequentially filled between the innermost cells 5 in the case 1, and the space R is also filled with the ceramic grains S from the innermost part to the left side to extinguish the fire. ..

Further, since the inert gas G in the case 1 is convected in the space R and then discharged from the exhaust port 10a of the exhaust pipe 10 to the outside of the case, the ceramic particles injected and supplied together with the new inert gas. The supply of S is performed smoothly.
At this time, with respect to the same left side wall surface of the case 1, the exhaust port 1
Since 0a is opened at the same height as the injection port 9a of the nozzle 9 and at a position separated in the horizontal direction, only the inert gas is discharged from the exhaust port 10a, and the ceramic particles S are separated from the space R. Exhaust port 1 until the entire interior is filled
0a is never closed.

Further, the present invention is not limited to the above-mentioned respective embodiments, and for example, the position of the temperature sensor 12 is provided inside the vent pipe 10, near the inlet or the outlet, or the cap 11 is omitted. For example, the configurations of the respective units can be arbitrarily modified and embodied without departing from the spirit of the present invention.

[0025]

As described above in detail, the present invention has an effect of enabling early fire extinguishing and preventing burning of a normal battery by detecting a fire of the battery in the case at an early stage.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a fire detection device in a sodium-sulfur battery embodying the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a partial circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a plan sectional view showing a third embodiment of the present invention.

[Explanation of symbols]

1 case, 5 assembled batteries, 10 ventilation pipe (exhaust pipe),
10a Opening (exhaust port), 12 Temperature sensor.

Claims (1)

Claim: What is claimed is: 1. A gas passage that penetrates the inside and outside of the case is provided on a side wall of a case that houses an assembled battery of sodium-sulfur batteries, and a gas flow path inside or through the ventilation pipe. A fire detection device in a sodium-sulfur battery, wherein a temperature sensor for fire detection is arranged in a part of the above.