RU2260228C2 - Pyrotechnical electric current supply - Google Patents

Abstract

FIELD: conversion of chemical energy of exothermic compositions into electrical energy.

SUBSTANCE: proposed stand-by expendable high-temperature pyrotechnical current supply has electrodes made of pyrotechnical compositions with separator also made of pyrotechnical composition in-between. In addition, pyrotechnical current supply has electrolyte which is, essentially, mixture of asbestos and inorganic salt, their proportion being as follows, mass percent: asbestos, 3 - 10; inorganic salt, 90 - 97. Butt-end surface area of electrolyte makes up 5 to 50% of that of separator and ratio of butt-end surface area of separator to that of each electrode is 1.03 to 1.4.

EFFECT: enhanced operating time and effectiveness of pyrotechnical current supply.

1 cl, 3 dwg

Description

The invention relates to devices for the direct conversion of chemical energy into electrical energy, in particular to high-temperature standby sources of electric current of a single action, designed to work in standby mode. They are used to autonomously activate and power on-board equipment, instruments and devices (incandescent bridges, pyroenergy sensors, microelectric motors, relays, etc.), as well as warning systems, automatic fire extinguishing systems, interlocks, etc.

Known pyrotechnic source (generator) of electric current (PGET) according to the patent of the Russian Federation No. 2095745 MKI F 42 C 11/00; H 01 M 6/20 dated 10.11.97, consisting of an anode and a cathode separated by a separator, made of pyrotechnic compositions with an excess of fuel — an anode, an excess of oxidizing agent — a cathode and current leads, the anode, cathode and separator containing asbestos and made with the ratio of their maximum size (diameter) to thickness 20 ... 130; as a fuel, the anode and cathode contain zirconium; as an oxidizing agent, the anode contains barium chromate or copper oxide; the cathode is copper oxide, and the separator contains molten ion-conducting salts - lithium fluoride, or alkaline earth metal fluoride, or a mixture thereof. In addition, the separator may additionally contain zirconium oxide in an amount up to 60% by weight.

The main disadvantages of the known device are the short time (generating electric current) and a long exit to the mode. This is due to the low burning rate of pyrotechnic electrodes due to the intense heat removal from the combustion zone to the electrolyte material of the separator that contacts them and melts when the electrodes burn. In addition, the characteristics of PGET are not stable enough due to leakage of molten electrolyte and melt short circuit of electrodes and cells.

The closest technical solution (prototype) is a pyrotechnic electric current generator according to the patent of the Russian Federation No. 2137263, MKI N 01 M 6/20; From 06 to 33/00. PGET consists of an anode and a cathode separated by a separator, made of pyrotechnic compositions, and current leads, and the anode, cathode and separator as a binder contain asbestos and are made with a ratio of the maximum overall size to thickness from 25 to 135. The separator is a mixture of fuel and oxidizing agent with asbestos in the following ratio of components (in% by weight):

metal fuel 14 ... 42 oxidizing agent 50 ... 84 asbestos 2 ... 8

The main disadvantages of the prototype are the long exit time of the device to the operating mode, short time (generating electric current) and low stability characteristics.

The objective of the present invention is to provide a small-sized pyrotechnic source of electric current (PIT) with increased operating time (up to 130 s), with a reduced exit time to operating mode up to 0.2 s, and high stability of characteristics. This problem is solved by the fact that in the known device, consisting of metal current leads and electrodes made of pyrotechnic compositions separated by a separator made of pyrotechnic composition, the PIT additionally contains an electrolyte made of a mixture of asbestos with inorganic salt (in% ratio by weight of components) :

asbestos 3 ... 10 inorganic salt 90 ... 97

wherein the area of the end surface of the electrolyte is from 5 to 50% of the area of the end surface of the separator, and the ratio of the area of the end surface of the separator to the area of the end surface of each of the electrodes is from 1.03 to 1.4.

The electrolyte can be placed between the separator and each of the electrodes, in addition, the separator can be made with a hole, and the electrolyte is placed in the hole of the separator. One of the electrodes can also be made with a hole, and the electrolyte can be placed both in the aforementioned hole and in the holes of one of the electrodes and the separator.

The main differences of the claimed device from the prototype are:

- the ratio of the area of the end surface of the separator to the area of the end surface of each of the electrodes from 1.03 to 1.4;

- the introduction of an electrolyte made from a mixture of asbestos with an inorganic salt (in% mass ratio of components: asbestos 3 ... 10; inorganic salt - 90 ... 97), and the area of the electrolyte end surface is from 5 to 50% of the end surface separator surfaces;

- placement of the electrolyte between the separator and each of the electrodes;

- making holes in the separator and placing the electrolyte separator in the hole;

- making a hole in one of the electrodes and placing an electrolyte in it (and in the separator hole).

A separator made with an end surface area larger than that of pyrotechnic electrodes is quickly and easily ignited, which reduces the time required to ignite the free (protruding beyond the electrodes) edge of the separator, and accordingly the pyrotechnic electrodes. This reduces the time from the moment the device is initiated to the moment the maximum value of the electric current is reached. At the same time, an increase in the duration of electric current generation is achieved due to better preservation of the operating temperature in the cell and battery of cells due to the formation of additional thermal insulation of the device from the products of closed porosity of the combustion products of the separator edge protruding beyond the boundaries of the electrodes, which ensures heat conservation and increases the duration of current generation.

An additionally introduced electrolyte between the separator and each of the electrodes increases the operation time of the PIT due to the optimization of the thermal regime of the PIT and the improvement of the ionic conductivity between the electrodes. Placing the electrolyte on an area of 5 to 50% of the area of the end surface of the separator eliminates the possibility of leakage of electrolyte outside the cell and shorting the electrodes and cells with each other, which improves the stability of the PIT parameters.

The implementation of the separator with the hole and the placement in the said hole of the electrolyte ensures minimal heat removal from the molten electrolyte, increasing the duration of its stay in the molten state while eliminating the possibility of leakage, which increases the operating time of the PIT and the stability of its characteristics, and also helps to increase the burning rate due to the minimum contact area separator with electrolyte, which reduces the delay time PIT.

The execution of one of the electrodes with a hole and the placement of the electrolyte in the aforementioned hole or in the hole of the separator and in the hole of one of the electrodes, in addition to the mentioned positive effects, stabilizes the characteristics of the PIT at significant negative temperatures.

However, the design of the inventive device provides heat after passing the combustion front due to the interaction of the reaction products of the anode, separator and cathode with each other in diffusion mode in an amount that compensates for the heat loss of the device into the environment, which ensures uniform temperature distribution throughout the entire volume of the claimed device (heat is generated in each thin-layer element of the electrochemical cell). All this helps to increase the duration of the work. In addition, the claimed design of the PIT increases the stability of its characteristics, eliminates the possibility of overheating, short circuits, noise and other manifestations of instability of current and voltage.

Inorganic salts that make up the electrolyte, such as lithium fluorides, alkaline earth metals - magnesium, calcium, strontium, barium, other salts, as well as mixtures of these and other salts when the separator and pyrotechnic electrodes are burned, completely or partially melt. The molten salts, together with asbestos and the products of the separator combustion, provide ionic conductivity between the anode and cathode. The electrolyte, additionally introduced into the inventive device, improves the ionic conductivity between the electrodes, stabilizes the combustion (heat release) and current generation processes due to the heat of phase transitions, primarily at the point of contact of the pyrotechnic electrodes and the separator with a mixture of asbestos and inorganic salt.

In the inventive device, asbestos is a binder. He also takes part in current-forming processes after the thermochemical effect of molten salts and the products of combustion of the separator and electrodes on it. Together with molten fluorides, their mixtures with other salts and the mentioned combustion products, asbestos provides ionic conductivity between the anode and cathode, which is a necessary condition for generating electric current by the proposed device.

When the ratio of the area of the end surface of the separator to the area of the end surface of each electrode is less than 1.03, the PIT characteristics are not improved. When the value of the mentioned parameter is greater than 1.4, the cell assembly process becomes non-technological, in addition, the thermal balance of the cells and the device as a whole is violated, in particular, due to a possible violation of the symmetry of the separator relative to the axis of the electrochemical cell and device, which reduces the stability of the released heat in the volume of the claimed device and its technical characteristics.

When the area of the end surface of the electrolyte is less than 5% of the area of the end surface of the separator, an increase in the duration of the generation of electric current is not provided. With an area of more than 50% - the product becomes low-tech. The decrease in the time for the PIT to enter the operating mode, due to the increase in the burning rate of the separator and the electrodes, becomes insignificant (insignificant). The amount of heat released decreases below the permissible value, which reduces the duration of the current generation and the stability of the characteristics. Only the claimed aspect ratio provides an improvement in the performance of PIT and their stability.

When the asbestos content in the electrolyte (its mixture with an inorganic salt) is less than 3%, the stability of the electrolyte formulation is not ensured, which reduces the stability of all characteristics of the claimed device. When the asbestos content in the mixture is more than 10%, an increase in the duration of the current generation time is not provided compared with the prototype.

The design of the inventive PIT provides the possibility of forming thin-layer pyrotechnic electrodes and a separator with a high sensitivity of each to the initiating pulse, which contributes to reliable ignition, fast and complete combustion, ensures the flow of electrochemical processes between the anode and cathode for a given time. The consequence of this is speed, high electrical characteristics, the ability to create multi-cell batteries of minimum height. In addition, the claimed design of the PIT provides the ability to manufacture electrodes, separators and electrolyte on semi-automatic lines using a high-performance and safe slip casting method (by vacuum deposition of an aqueous suspension of components).

The inventive PIT, figa, figb, figv, is an elementary electrochemical cell, in which the anode 1, cathode 3 and the separator 2 are made of pyrotechnic compositions and placed coaxially between the metal current leads 5 and 7. Electrolyte 4 can be placed between the separator 2 and each of the electrodes 1 and 3, figa. The electrolyte can also be placed in the hole of the separator 2, FIG. 1B, or in the hole of one of the electrodes, or in the holes of the separator and one of the electrodes, FIG. 1B (in FIG. 1B, the hole in one of the electrodes is conventionally shown on the cathode).

The ratio of the area of the end surface of the separator to the area of the end surface of each of the electrodes is from 1.03 to 1.4. The surface area of the additionally introduced electrolyte 4 is from 5 to 50% of the surface area of the separator in the following ratio of components (in% by weight):

asbestos 3 ... 10 inorganic salt 90 ... 97

The inorganic salt used is lithium fluoride, or alkaline earth metal fluoride, or a mixture of fluorides, or a mixture of metal fluoride, or a mixture of metal fluorides with other inorganic salts.

From the claimed PIT can be collected batteries (sets of any number of the above devices connected in series or in parallel) to provide the necessary electrical parameters.

The inventive PIT works as follows. Separator 2 made of a pyrotechnic composition ignites and burns from the initiating pulse, for example, as in RF patent No. 2137263. Moreover, depending on the specific formulations of the anode 1 and cathode 3, the cathode 3 or (and) anode 1 can be ignited and burned, made of pyrotechnic compositions. (For example, a cathode with an excess of oxidizing agent, as in RF patents No. 2088558, No. 2095745, No. 2137263, etc., and (or) an anode made of a pyrotechnic composition with excess fuel, as in RF patents No. 2088558, No. 2095745, 2137263, etc.).

In the claimed PIT already at the moment of ignition of the separator 2 and electrodes 1, 3 (or one of them), the generation of electric current begins - the transfer of electrons through the external circuit from the anode 1 through the anode current output 7, the load (resistance) 6, the cathode current output 5 to the cathode 3 The movement of charged particles (electrons and ions) is due to the electrochemical oxidation of the spatially separated fuel separator 2 in the anode 1 and the electrochemical reduction of the oxidizer in the cathode 3 due to the simultaneous contact of the electrodes with the ion-conducting electron ektrolitom 4.

The insignificant thickness of the electrodes 1 and 3, the separator 2 and the electrolyte 4, forming the inventive device, provides, along with speed, long time of generation of electric current and stability of characteristics, the minimum dimensions of PIT and batteries from the inventive device. In this case, additional heat is generated in each cell during the generation of current, which compensates for heat loss to the environment and stabilizes the characteristics.

The design optimization of PIT was carried out on the basis of laboratory (bench) and field tests, which showed the high efficiency of the proposed facility.

The inventive PIT provides autonomous activation and power supply for 130 s on-board equipment, instruments and devices, as well as pyroautomatics systems for various purposes (fire extinguishing, alarm, warning, blocking, etc.). As part of the PIT sensors, it independently and remotely turns on extinguishing and warning means when the sensor reaches the specified critical temperature, for example, in storage and (or) production rooms with fire and explosive materials or technological processes, etc.

The test results confirmed the high efficiency of the claimed device. The delay time for starting the operation of the PIT (the time it takes to operate) is up to 0.2 s, which is 1.3 ... 2 times less, and the duration of operation (current generation) is 130 s, which is 30% more than the prototype . Combustion products shrink 1.5 to 3 times less, which improves the specific characteristics of PIT and their stability by 30 ... 40%. Batteries of two or more of the claimed devices connected in series provide a long and stable current generation after the initiation pulse is supplied. The larger the number of cells in the battery, the shorter the time it takes to reach the operating value of the parameters, the longer the operation time, and the lower the rate of decline in performance over time. In particular, a battery of 24 PIT generates a current at a load of 300 ohms for 130 s. The time to reach the operating voltage value is not more than 0.2 s.

Claims (1)

Pyrotechnic electric current source, consisting of current leads and electrodes made of pyrotechnic compositions separated by a separator made of pyrotechnic composition, characterized in that it additionally contains an electrolyte made of a mixture of asbestos with inorganic salt (in% weight ratio of components): Asbestos 3 ... 10 Inorganic salt 90 ... 97 wherein the area of the end surface of the electrolyte is from 5 to 50% of the area of the end surface of the separator, and the ratio of the area of the end surface of the separator to the area of the end surface of each of the electrodes is from 1.03 to 1.4.

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