This invention pertains to a Reserve Battery activated by shock with spin which can reliably deliver electrical power. This Reserve Battery has a long storage life and high power capabilities which makes them useful for military applications especially for Fuzes used in ammunitions which need to be fired using Propellant charges with low mass. The increased shelf-life, higher energy density and faster activation make it more attractive when compared with the batteries under this class.

In military operations, the role of fuzing system for the projectile war head/ shell is very important, which is responsible for the safety in handling as well as for the timely initiation of the explosion of the projectile. Hence for a projectile during it's flight, a reliable power source with adequate power density with rapid activation is an essential requirement to the Electronic fuze. Fuze has many parts like controllers, timing circuitry, and various sensors. Additionally, the fuze has a safety and arming device to ensure that both the arming and detonation of the projectile occur only at a desired moment.

As part of our endeavour to develop power source for the Fuze of the ammunition with propellant of low charge, with quick activation and long storage life, we have developed yet another state of the art battery which comply the requirement of MIL-STD 331C, and MIL-STD 810G. Such batteries are very effective in operation in environments that may be subjected to very low sub-zero temperatures or very high terrestrial temperatures.

The Battery under our invention has been provided utilizing such high density battery cells, so that they will be available for desired applications, though the battery may be kept in storage for relatively long periods of time before being called into service. They should be able to be activated for immediate service when required. The uniqueness of our design is its 100% reliability when compared to the batteries available at present.

The state of the art Reserve Battery under our invention can be activated by shock and simultaneous spin. This battery is more appropriately used for the Fuze for all smart ammunitions. In such applications, the battery should activate when the ammunition is fired using propellant charges having different charge mass. Contemporary Reserve Batteries are not reliable when using ammunition with propellant having low charge mass, as one cannot be sure of the battery activation and may render the ammunition unreliable during combat operations.

The Battery under our invention has plurality of cell stacks of annular lithium electrodes and carbon electrodes separated by a glass separator and placed one over the other and further separated by a plastic annular disc or a plastic cup and connected to each other in series. The connections are suitably potted with a sealant on the outside of the stack arrangement or heat sealed to avoid shorting or current leakages. An ampoule filled with
Thionyl chloride electrolyte is kept under tension by means of a spring fixed to the base of the former, below the ampoule. An activating system consisting of an anvil fixed to the former below the ampoule causes to break the ampoule during activation resulting in the flow of electrolyte from confinement. The entire assembly is housed in a battery case. On firing the ammunition, the ampoule kept under tension by the spring is broken by the anvil due to set back action and makes the electrolyte to flow out of the ampoule and enter into the electrode arrangement due to the spin of the projectile in which the battery is assembled, commencing the electrochemical reaction and electrical power can be drawn.

Accordingly our invention pertains to a reserve battery activated by shock and spin comprising a cell stack of electrodes; an ampoule containing an electrolyte; an activating system; a former; a battery case in which the said cell-stack, ampoule and activating system are placed and closed by a battery lid characterized wherein the cell-stack of electrodes has annular shape comprising of carbon electrode and lithium electrode separated by a glass separator placed one over the other, wherein the said stack arrangement is isolated from one another by means of another separator selected from non - conducting plastic or phenolic disc or a plastic or phenolic cup and a glass ampoule protected with a flexible rubber sleeve over which a lead weight is assembled as a proportional weight compensation element for the ampoule having Thionyl Chloride electrolyte, positioned at the hollow portion of the former above the activating system of the battery which comprises of an anvil and a spring fixed firmly at the cell support disc at the base of the battery and capable of breaking the ampoule/ resting on the spring, at a predetermined acceleration and capable of distributing the electrolyte into the void space of the cells, thereby activate the cells and generate electrical power, wherein the above sub assembly is enclosed in a battery case and closed with the battery lid and further covered by inserting in a plastic battery cover tightly and suitably closed with a plastic lid.

Now the invention will be described in more detail with reference to the accompanying drawings bringing out the embodiments of the arrangement according to the invention.

Fig. 1 Exploded view of Reserve Battery activated by Shock and spin

Fig. 2 Exploded view of Reserve Battery activated by Shock and spin in another embodiment under the invention

Fig. 3 Sectional view of the Reserve Battery activated by shock and spin

Fig. 4 Sectional view of the Reserve battery activated by Shock in another embodiment under the invention

Fig. 5 Isometric view of the cell stack arrangement,

Fig. 6 Isometric view of the cell stack arrangement in another embodiment under the invention

Fig. 7 Isometric view of the Battery lid

Fig. 8 Isometric view of cell cup

Fig. 9 Battery activation graph at different temperatures

Fig. 10 Battery performance curve at different temperatures Wherein

1) Plastic battery cover, 2) Metallic Battery case, 3) Lead weight, 4) Flexible rubber sleeve, 5) Glass ampoule, 6) Spring, 7) Anvil, 8) Former, 9) Cell stack, 10) cell support disc, 11) Battery lid, 12) Positive terminal, 13) Fuze locater pin, 14) glass to metal seal, 15) Plastic lid, 16) electrolyte entry slot, 17) cell locking arrangement, 18) Groove for terminals, 19) Lip for heat sealing, 20) cell cup/ plastic or phenolic disc, 21) Carbon electrode, 22) Separator, 23) Lithium electrode, (24) Slit for electrolyte to flow into the cell stack arrangement, (H.T) High temperature, (R.T) Rroom temperature and (L.T) Low temperature.

The major parts of the reserve battery under our invention are, Cell stack (9) of electrodes; Glass ampoule (5) containing electrolyte; an activating system comprising of anvil (7) and spring (6); a former (8) to hold ampoule and to keep the cell stack and the activating system in position. Further, the said cell stack of electrodes, anvil and spring are held over a cell support disc (10) which insulates the cell stack arrangement from the metallic battery lid (11); the above components are assembled inside a specially designed metallic battery case (2) and closed by the battery lid having the positive terminal (12) and fuze locater pin (13). A plastic battery cover is provided to cover the battery to protect it against accidental shocks.

In one of the embodiments under our invention, the electrodes are monopolar. The cell stack arrangement in the said invention is comprising of metallic lithium sheet blanked in the shape of an annular disc pressed on a metal wire mesh selected from' nickel, stainless steel, silver, or any suitable metal which is also blanked in the shape of an annualr disc, forming the lithium electrode (23) to function as cathode, and carbon powder pasted on a metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal forms the carbon electrode (21) followed by curing and blanking the carbon pasted and cured sheet in the shape of an annular disc and functions as anode. The lithium electrode is made by pressing the blanked annular shaped metallic lithium sheet of predefined thickness on the selected wire mesh, to which a Nickel strip is attached preferably by resistance. welding, prior to pressing lithium. This nickel strip functions as the lead for drawing electric power. Later on, this nickel strip is soldered to the body of the Battery case (2), once the former with electrode assembly is inserted into the Battery case (2).
The process is done in a dry inert atmosphere with a very low relative humidity and low temperature, as lithium is highly reactive and hydrolyzes even if subjected to atmospheric moisture and can form nitrate compounds with atmospheric air in presence of moisture.
The carbon electrode (21) is made by pasting a mixture of carbon powder and a binder preferably polytetrafluoroethylene suspension on a metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal, followed by curing and blanking the sheet in the shape of an annular disc, to which a nickel strip is attached preferably by resistance welding. This nickel strip which functions as the positive lead is welded to the positive terminal (12) of the battery lid (11), once the former with electrode assembly is inserted in the Battery case. The electrodes are separated by an insulating material, selected form cellulosic paper, polythene film, nylon film, and glass mat, preferably a non woven glass mat insulating medium called herein after as separator (22) in the present invention. The cells are made by placing the annular lithium electrode (23), separator (22) and carbon electrode (21) one over the other in the respective order, such that the electrodes insulated from each other by the separator, and this arrangement is located in the cell cup. The cell cup is provided with a groove on the outer side for drawing the terminals of the electrodes and joining them suitably. The area where welding is done is insulated by applying a sealant mixture containing a resin and accelerator. This arrangement is cured to ensure effective sealing. The cell cups thus arranged one over the other are locked to one another by locating the cell cups into the cell locking arrangements, and the lips (19) provided on the outer side of the cell cups are heat sealed or potted or both heat sealed and potted to prevent seepage of electrolyte and subsequent cell shorting during battery operation. Once the cell assembly is completed, this cell stack is placed suitably, over the cell support disc (10).

In another embodiment under our invention, electrodes are designed as monopolar. In this model, Lithium electrode is made by pressing a blanked annular lithium metal disc to a metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal and welding it to a metal sheet selected from nickel, stainless steel, silver, or any suitable metal which is pasted with metal powder selected from nickel, stainless steel, silver, or any suitable metal powder slurry made by the addition of suitable binder and sintered to which a Nickel strip is attached preferably by resistance welding, prior to pressing lithium. This nickel strip functions as the lead for drawing electric power. Later on, this nickel strip is soldered to the body of the Battery case (2), once the former with electrode assembly is inserted into the Battery case (2). The carbon electrode (21) is made by pasting a mixture of carbon powder and a binder preferably polytetrafluoroethylene suspension on a metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal and curing followed by welding it to a metal sheet selected from nickel, stainless steel, silver, or any suitable metal which is pasted with metal powder selected from nickel, stainless steel, silver, or any suitable metal powder slurry made by the addition of suitable binder and sintered. The said sheet, is blanked in the shape of annular disc to which a nickel strip is attached preferably by resistance welding. This nickel strip which functions as the positive lead is welded to the positive terminal (12) of the battery lid (11), once the former with electrode assembly is inserted in the Battery case. The electrodes are separated by an insulating material, selected form cellulosic paper, polythene film, nylon film, and glass mat, preferably a non woven glass mat insulating medium called herein after as separator (22) in the present invention. The cells are made by placing the annular lithium electrode (23), separator (22) and carbon electrode (21) one over the other in the respective order, such that the electrodes insulated from each other by the separator, and this arrangement is located in the cell cup. The cell cup is provided with a groove on the outer side for drawing the terminals of the electrodes and joining them suitably. The area where welding is done is insulated by applying a sealant mixture containing a resin and accelerator. This arrangement is cured to ensure effective sealing. The cell cups thus arranged one over the other are locked to one another by locating the cell cups into the cell locking arrangements, and the lips (19) provided on the outer side of the cell cups are heat sealed or potted or both heat sealed and potted to prevent seepage of electrolyte and subsequent cell shorting during battery operation. Once the cell assembly is completed, this cell stack is placed suitably, over the cell support disc (10).

In one other embodiment, Electrodes are designed as bipolar. In this model, Plastic or phenolic sheet with or with out copper mask on either side and plated with suitable metal is blanked in the shape of annular disc, to one side of the said sheet, metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal is placed. To this mesh, Metallic Lithium sheet which is blanked in the shape of annular disc is pressed. On the other side of the said disc, a carbon electrode blanked in the shape of an annular disc is placed, which is made by pasting carbon powder followed by curing, over a metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal. These two electrodes are welded at 3 spots along the annular space of the plastic disc. Bipolar electrode is thus made. Series of such bipolar electrodes are placed one over another with lithium and carbon electrodes facing one another, and separated by a non woven glass mat separator.

In yet another embodiment under our invention, electrodes are designed as' bipolar. In this model, metal sheet selected from nickel, stainless steel, silver, or any suitable metal is pasted with metal powder selected from nickel, stainless steel, silver, or any suitable metal powder slurry made by the addition of suitable binder on both sides and sintered.
To one side of the said sintered sheet, carbon paste is applied and cured. The said sintered sheet, after curing is blanked in the shape of annular disc. To the other side of the sintered sheet, metallic Lithium sheet, blanked in the shape of an annular disc is pasted. Series of such electrodes are placed one over the other, such that lithium and carbon face one another and are separated by a non woven glass mat separator.

The Glass ampoule (5) is made from glass tube, preferably of boro silicate glass and will hold the electrolyte in it, as boro silicate glasses are known for having very low coefficients of thermal expansion (~3x10_06/oC at 20°C), making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and is commonly used for the construction of reagent bottles also. The electrolyte is filled in the ampoule, preferably in a dry inert atmosphere with a very low relative humidity and low temperature, and then the neck is closed suitably by TIG welding or flame welding or laser welding to prevent the electrolyte to come out of the ampoule before the battery is activated. The neck of the ampoule (5) is protected by putting a flexible rubber sleeve (4), preferably made of viton rubber. This flexible rubber sleeve protects the neck of the glass ampoule from shocks arising out of accidental fall as well as during transportation of the battery, which may damage the ampoule and cause the electrolyte to leak into the cell stack arrangement. Further, lead weight (3) is assembled over this viton rubber sleeve and the weight is decided based on the weight of ampoule. It functions as weight compensation element corresponding to the weight of the ampoule so chosen. Under the present invention, the weight of the ampoule plays a significant role during activation during firing conditions. As an illustration, if the glass ampoule chosen is weighing 10 grams and the firing shock is 1500 'g' then the apparent weight of the ampoule becomes 15Kg.

Hence even a reduction of 1 gram in the weight of the ampoule would bring down its apparent weight during firing by 1.5 Kg, which may lead to non activation of the battery. So the difference of this 1 gram weight is compensated by way of putting a lead weight over the flexible rubber sleeve, complimenting the weight of the ampoule and thus ensuring reliable activation of the battery. Electrolyte used for this type of reserve battery is Thionyl chloride, with Bromine, chlorides of Potassium, Aluminium, and Lithium as additives.

The former (8) houses the glass ampoule (5), spring (6) and the anvil (7). The former can be of cylindrical shape for comfortably housing of the glass ampoule which also is in cylindrical shape. In one of the embodiments, the former assembly comprises of two parts. Viz., a top cylindrical portion for housing the ampoule essentially called the former (8), and a cell support disc (10) at the base at the cell stack arrangement. The cell support disc supports the cell stack arrangement and has provision for locating the anvil (7), and spring (6).

In another embodiment, the former is made in the form of a hollow cylinder (8) with a flat base which also functions as the cell support disc (10). This flat base has a diameter larger than the diameter of the cylinder for holding the cell stack arrangement. Anvil (7) and spring (6) will be assembled inside the hollow cylindrical space of the former. The shape of the former is chosen strategically, so as to ensure effective protection for ampoule from lateral shocks and also to ensure uniform movement of the ampoule onto the anvil, as well as to locate the electrode stack firmly and precisely. In this embodiment, the former is provided with vertical or angular or parabolic or intermittent or alternating slits (24) on the sides, which act as channels for electrolyte to flow. These slits also prevent the glass pieces from entering into the cell stacks and thus protect them from getting damaged. This type of former is generally preferred, when the cell stack arrangement is in the form of bipolar stacks.

The cell support disc (10) holds the anvil (7), spring and cell stack firmly. The spring is assembled over the anvil (7) and the glass ampoule is placed over the spring. The anvil is made from foil or block of solid metal or plastic, in the form of a shear cutter or a plurality of pins located strategically to puncture and simultaneously break the ampoule preferably a shear cut. The shock received by the anvil during the ammunition firing is imparted to the glass ampoule (5) holding the electrolyte kept under tension by means of spring, when the ampoule apparently travels backwards during firing, thereby enabling the ampoule to be crushed, allowing the electrolyte to flow out of the ampoule and enter into the voids in cell stacks by way of set back effect.

The battery case (2) can be made of metal, preferably Nickel, SS 304 or Plated MS to withstand the corrosive action of electrolyte. In the preffered embodiment, the material selected battery case is SS 304. The Battery The shape is selected from any suitable profiles like cylindrical, square, conical, or based on the customer's requirement. In one of the embodiments under our invention, the shape of the battery case is as shown in the figures 1,2,3 and 4. The truncated cone shape on top of the battery followed by cylindrical portion prevents the crumbling of the battery due to the shock generated during firing. Further, it facilitates to employ a longer spring which provides more cushioning effect by bringing down the threshold value of the setback shock. This in turn helps the activation of the battery with a lower propellant charge. The Battery case can hold one or more cells, as defined by the voltage requirements. In the preferred embodiment, the battery case is constructed to house multi-cell system.

The Battery lid (11) is having two holes, one for fixing the positive terminal (12) for the power out put and second for assembling the fuze locater pin (13), which enables the battery to get it locked into the fuze. Battery body acts as the negative terminal. The battery lid is finally welded to the battery case by laser welding or tig welding. The Battery case, after complete assembly of the battery and closing by the battery lid is further covered by inserting in a plastic battery cover (1) tightly and suitably closed with a plastic top lid (15). This arrangement not only facilitates extra protection for the battery by protecting them from accidental activation due to mishandling of the Fuze systems, but also facilitates in preventing the battery from collapsing when the fuzes are subjected to firing using propellant with high charge mass. Further this arrangement has the distinct advantage of giving customised shape to the battery as stipulated by the end user regarding the space available for accommodating the battery inside the fuze.'

Special features of the battery under our invention are as under

• This battery is designed to reliably activate when subjected to shocks in excess of 1500'g's and a spin in excess of 2000 rpm, when the ammunition is fired with low weight propellant charge. This kind of reliability cannot be expected from the contemporary Lithium Reserve batteries presently.

• The former is designed in such a way that the inner walls of the former act as guide for the ampoule for direct fall on to the anvil

• Flexibility in design is available for increasing the voltage by introducing plurality of electrode stacks

• The Battery is designed in such a way that it does not activate when dropped from a mandatory height of up to 1.5 meters, as required by the MIL-STD wherein a momentary high shock in the order of 6000 'g' is effected on the former, but at the same time can activate the battery when subjected to a sustained shock of the order of 1500 'g' or more. This is one of the special features of this battery.

Some of the features as per one of the embodiments under which proto type is made are given below by way of reference and is not a limitation, as possibilities exist to increase the capacity and mode of activation by suitably altering without deviating from the ambit of this invention.

General Characteristics

1. Electro chemistry: Lithium/Thionyl Chloride(Li/SOCI2)
2. Storage Life: 20 years
3. Configuration: multi cell stack as per voltage requirement

Performance Characteristics

1. Operating Voltage: >27.0 Volts
2. Current: 30 mA
3. Capacity: >10.0 mAh
4. Activation Time: <250 milli seconds (> 15.0 Volts)
5. Run Time: >180 seconds

Dimensions

1. Diameter (nominal): 38.0 mm
2. Length (nominal): 32.0 millimetres (w/o terminals)
3. Weight (nominal): <50.0 grams Physical Characteristics
1. Operating Temperature Range: -40°C to +70°C
2. Storage Temperature: -54°C to +70°C
3. Connector: 2 Pins: One pin as the Power terminal (the second terminal being the body).The other one is locating pin.
4. Activation Mechanism: Shock +Simultaneous spin
5. Case & Mounting Flange: Stainless Steel

Environmental Characteristics

Designed to meet the requirements of MIL-STD 331C & MIL-STD 810G Environmental safety requirements.

Applications: Smart ammunitions., Electronic Fuzes for artillery tank shells, Howitzers etc.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments, thereof, variations and modifications can be effected within the spirit and scope of the invention as described herein above and as defined in the appended claims.

We claim

1. A reserve battery activated by shock and spin comprising a cell stack of electrodes; an ampoule containing an electrolyte; an activating system; a former; a battery case in which the said cell-stack, ampoule and activating system are placed and closed by a battery lid characterized wherein the cell-stack of electrodes has annular shape comprising of carbon electrode (21) and lithium electrode(23) separated by a glass separator (22) placed one over the other, wherein the said stack arrangement is isolated from one another by means of another separator selected from non-conducting plastic or phenolic disc or a plastic cup (20) and a glass ampoule (5) protected with a flexible rubber sleeve (4) over which a lead weight (3) is assembled as a proportional weight compensation element for the ampoule having Thionyl Chloride electrolyte, positioned at the hollow portion of the former (8) above the activating system of the battery which comprises of an anvil (7) and a spring (6) fixed firmly to the cell support disc (10) at the base of the battery and capable of breaking the ampoule, resting on the spring, at a predetermined acceleration and capable of distributing the electrolyte into the void space of the cells, there by activate the cells and generate electrical power wherein the above sub assembly is enclosed in a battery case (2) and closed with the battery lid (11) and further covered by inserting in a plastic battery cover (1) tightly and suitably closed with a plastic lid (15).

2. A reserve battery activated by shock and spin as claimed in claim 1 wherein the battery case (2) is made of metal selected from Nickel or SS 304, or Plated MS or any suitable alloy/ metal and the shape is selected from any suitable profiles like cylindrical, square, and conical.

3. A reserve battery activated by simultaneous shock and spin as claimed in claim 1 wherein the battery case (2) is in the shape of truncated cone on top followed by cylindrical portion to prevent the crumbling or deformation of the battery due to the shock generated during firing the ammunition and to facilitates to employ a longer spring which is capable of providing more cushioning effect even in the event of accidental drop and also to bring down the threshold value of the set back shock which in turn helps the activation of the battery with propellant of low charge mass.

4. A reserve battery activated by shock and spin as claimed in claim 1 wherein the electrode stack comprises of annular lithium electrode (23), separator (22) and carbon electrode (21) one over the other in the respective order, such that the electrodes are insulated from each other by a non woven glass mat separator (22), and located in another separator selected from non-conducting plastic or phenolic disc or a plastic cup (20) and positioned one over the other and locked into the cell locking arrangements (17) wherein the lips (19) provided at the outer side of the cell cups can be heat sealed or potted or both heat sealed and potted to prevent seepage of electrolyte and consequent cell shorting during battery operation, forming stack of single cells which in turn are connected in series out side the stacks with high reliability.

5. A reserve battery activated by shock and spin as claimed in claim 1 wherein the electrode stack is made from plastic/ phenolic annular disk with copper mask on either side and plated with suitable metal with inter connection between the metallic surfaces, pressed with a combination of metal wire mesh selected from nickel, stainless steel, silver, or any suitable metal and Lithium metal sheet on one side, and a wire mesh selected from Nickel, stainless steel, silver or any suitable metal mesh pasted with carbon powder followed by curing on the other side and the said electrode set is welded at plurality of spots on the surface to form a bipolar electrode which are placed one over the other with lithium and carbon electrodes facing one another and separated by a non woven glass mat separator and such set of electrodes further separated by cell cup or cell disc and capable of placing suitably, over the cell support disc (10).

6. A reserve battery activated by shcck and spin as claimed in claim 1 wherein metal sheet selected from Nickel, stainless steel, silver, or any suitable metal is pasted on both side with slurry made from the metal powder selected from Nickel, stainless steel, silver/or any suitable metal by the addition of suitable binder and sintered and to one side of the said sintered sheet, carbon paste is applied and cured and blanked in the shape of annular disc and to the other side of the sintered disc, Lithium metal sheet blanked in the shape of an annular disc is pressed and series of such electrodes capable of placing one over the other, such that lithium and carbon electrode face one another and are separated by a non woven glass mat separator, and such sets of electrodes further separated by cell cups or cell disc placed suitably, over the cell support disc (10), wherein the outer surface of such stack is potted with suitable binder or heat sealed and insulated prior to assembly in to the battery case (2).

7. A reserve battery activated by shock and spin as claimed in claim 1 wherein the shape of the former (8) is chosen to ensure effective protection for the ampoule from lateral shocks and for the uniform movement of the ampoule onto the anvil as well as to locate the electrode stack firmly and the said former is provided with vertical or angular or parabolic or intermittent or alternating slits (24) on the sides to facilitate to function as channels for the flow of electrolyte.

8. A reserve battery activated by shock and spin as claimed in claim 1 wherein the neck of the ampoule (5) is protected with a flexible rubber sleeve (4), preferably made of Viton rubber and assembled with lead weight (3) over the said rubber sleeve as weight compensation element corresponding to the weight of the ampoule so chosen.

9. A reserve battery activated by shock and spin as claimed in claim 1 wherein the anvil (7) is made from foil or block of solid metal or plastic, in the form of a shear cutter or a plurality of pins located strategically to puncture and simultaneously crush the ampoule preferably a shear cut.

10. A reserve battery activated by shock and spin as claimed in claim 1 substantially herein described with reference to and illustrated in figure 1 to 10 of the accompanying drawings.