APPARATUS AND METHOD SUITABLE FOR USE WITH A MUNITION

Abstract

Apparatus and method suitable for use with a munition According to an aspect of the invention, there is provided a fuze arming system for a munition, comprising: an arming circuit arranged to detect a setback event and, in response to the setback event, generate a signal indicating that an arming event has occurred, wherein the arming circuit comprises a sensor configured to produce a graduated output when the setback event occurs, and fuze arming system is arranged to use that graduated output.

Claims

1. A fuze arming system for a munition, the fuze arming system comprising: an arming circuit arranged to detect a setback event and, in response to the setback event, generate a signal indicating that an arming event has occurred; wherein the arming circuit comprises a sensor configured to produce a graduated output when the setback event occurs, and the fuze arming system is arranged to use that graduated output; and wherein a graduation of the graduated output is proportional to a degree of setback detected during the setback event, and the graduation of the graduated output is used for providing information on one or more launch conditions of the munition.

2. The fuze arming system of claim 1, wherein the graduated output is used for arming a fuze, and/or programming a fuze, the fuze being in connection with or forming part of the fuze arming system.

3. The fuze arming system of claim 1, wherein the graduated output is used for programming a fuze, in addition to arming of the fuze.

4. The fuze arming system of claim 3, wherein the graduated output is used for programming a post-launch arming delay of the fuze.

5. The fuze arming system of claim 1, wherein the one or more launch conditions comprises an approximate muzzle velocity.

6. The fuze arming system of claim 1, wherein the sensor comprises a solid-state sensor, a piezoelectric sensor, or a magnetostrictive sensor.

7. The fuze arming system of claim 1, wherein a sensing axis of the sensor is aligned with a main acceleration axis of the munition.

8. The fuze arming system of claim 1, wherein the arming circuit further comprises: a capacitor arranged to store a voltage corresponding to the graduated output generated by the sensor.

9. The fuze arming system of claim 8, wherein the arming circuit further comprises: a rectifier; and/or a bleed resistor.

10. The fuze arming system of claim 1, wherein, in response to verifying that an arming event has occurred, the arming circuit is configured to output a signal to arm a fuze.

11. The fuze arming system of claim 10, wherein the fuze comprises an electronic fuze.

12. The fuze arming system of claim 1, wherein the sensor is configured to generate a charge when the setback event occurs.

13. The fuze arming system of claim 1, wherein the sensor is configured to produce the graduated output before a power source of the munition is activated.

14. A munition comprising the fuze arming system of claim 1.

15. A fuze arming method for a munition, the method comprising: detecting a setback event; responsive to the setback event, generating a signal that an arming event has occurred; and responsive to the setback event, producing a graduated output, and using that graduated output, wherein a graduation of the graduated output is proportional to a degree of setback detected during the setback event, and the graduation of the graduated output is used for providing information on launch conditions of the munition.

16. The method of claim 15, wherein the graduated output is used for arming a fuze and/or programming a fuze.

17. The fuze arming system of claim 8, wherein the arming circuit further comprises: a comparator circuit arranged to compare the voltage stored by the capacitor with a threshold value to verify whether an arming event has occurred.

18. A fuze arming system for a munition, the system comprising: an arming circuit arranged to detect a setback event and, responsive to the setback event, generate a signal indicating that an arming event has occurred; wherein the arming circuit includes a sensor configured to produce a graduated output responsive to the setback event, a graduation of the graduated output being proportional to a degree of setback detected during the setback event; wherein the graduation of the graduated output provides non-binary information about one or more launch conditions of the munition; and wherein the fuze arming system is arranged to use the non-binary information to arm a fuze and/or program the fuze.

19. The fuze arming system of claim 18, further comprising the fuze.

20. A munition comprising the fuze arming system of claim 19.

Description

[0043] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic Figures in which:

[0044] FIG. 1 schematically depicts a fuze arming system, in accordance with an example embodiment;

[0045] FIG. 2 schematically depicts an arming circuit, in accordance with an example embodiment;

[0046] FIG. 3 schematically depicts a munition comprising the fuze arming system, in accordance with an example embodiment;

[0047] FIG. 4 schematically depicts a fuze arming method for a munition, in accordance with an example embodiment.

[0048] As discussed above, there are numerous disadvantages associated with existing apparatus and fuze arming methods for munitions. These range from the inability to detect setback events that occur before its electrical power supply is available, to the limited design flexibility, or the significant expense associated with existing fuze arming systems. In general, there is exists no relatively inexpensive, flexible design that would provide a robust additional or alternative safety feature which may allow a particular type of fuzing, for example electronic fuzing, to be applied more safely, or more widely across a greater range of munition types, ranging anywhere from artillery shells to 5.56 mm bullets.

[0049] According to the present disclosure, it has been realised that the problems associated with existing approaches can be overcome in an inexpensive but effective manner. In particular, the present disclosure provides a fuze arming for a munition. The munition comprises an explosive charge and a fuze. The munition is adapted to be launched, into the air. Importantly, the munition may be adapted to be launched from a gun barrel. This means that the munition typically (and practically likely) includes, or is at least used in conjunction with, a propelling explosive, and is capable of being explosively propelled and withstanding such explosive propulsion.

[0050] The munition will typically be a projectile, therefore being unpropelled and/or including no form of self-propulsion. This means that the munition is relatively simple and inexpensive.

[0051] FIG. 1 schematically depicts a fuze arming system in accordance with an example embodiment. In this example, the fuze arming system 100 for a munition comprises an arming circuit 102 arranged to detect a setback event. The setback force is the rearward force of inertia resulting from the forward acceleration of a projectile (in this case, a munition) during its launching phase, applied in the direction along of the path of travel of the projectile. That is, the setback force is the force generated as the munition is initially accelerated. At least two separate environments must be detected in order to permit arming. Mechanical artillery fuzes typically use separate, independent mechanisms to detect setback and spin. Rotational arming requires that a munition reaches a certain rpm before an arming event occurs. Thus, by detecting a setback event, and using that to indicate that an arming event has occurred, earlier arming or safer might be achieved. Arming based on setback is beneficial in situations where early arming is requiredfor example, when the munition has a relatively short distance to travel to the target.

[0052] In response to detecting the setback event, the arming circuit 102 is configured to generate a signal indicating that an arming event has occurred. Throughout this specification, an arming event will be understood as an event representing a point in time at which the fuze may be armed; for example, the munition reaching its peak acceleration. It is noted that a plurality of different arming events might be required before the fuze is armed, in order to improve safety of the munition. This does not necessarily mean that the fuze can trigger an explosive charge, based on the detection of the setback event, and/or generation of the signal indicating that the arming event has occurred. Other conditions may need to be met. Important is that the generation of the signal indicating that the arming event has occurred may occur before a power source 104 of the system is fully activated. In other words, setback occurs, and is detected, before the power source 104 is usable or able to provide power to sensing or processing electronics. This is because a power source 104 of a munition is often itself triggered to be in an active or suitably power-supplying state based on launch of the munition. For example, component parts of the power source 104 may move or change state as the munition is launched, and this movement or state change moves the power source 104 to a power-supplying state. However, this takes time, and means that anything within or before that time simply cannot be detected by any sensor powered by that power supply.

[0053] The signal generated by the arming circuit 102 might be outputted via the output 106, and fed to another element of the fuze arming system, or another element of the munition, for example a control module within the munition.

[0054] In the example depicted in FIG. 1, the arming circuit 102 comprises a sensor 108 configured to produce a graduated output when the setback event, and the fuze arming system 100 is arranged to use that graduated output. The graduated output is used for arming a fuze, and/or programming a fuze, the fuze being in connection with or forming part of the fuze arming system 100. A graduation of the graduated output is proportional to a degree of setback detected during the setback event. In particular, the graduation of the graduated output is used for providing information on launch conditions of the munition, for example charge increment, which might or relate to an equivalent approximate muzzle velocity, corresponding to the detected degree of setback. Advantageously, the sensor 108 is configured to produce the graduated output before the power source 104 of the munition is activated.

[0055] In one example, said graduated output is used by the arming circuit 102 for generating the signal indicating that an arming event has occurred. The sensor 108 comprises anything that is able to generate a charge from a change in pressure (e.g. stress or strain) on the sensortypically, this is a solid-state sensor, such as a piezoelectric sensor, or a magnetostrictive sensor, or a combination thereof. The advantage of the aforementioned sensors is that they do not require an external power source to operatefor example, a piezoelectric sensor converts mechanical strain directly to electrical charge and thus does not require a power source to operate. A magnetostrictive sensor also change in mechanical energy to changes in electromagnetic energy. Thus, the sensor 108 is able to produce a graduated output when the setback event occurs, before a separate (e.g. external to and separate from the sensor 108) power source 104 becomes available. The fact that the sensor 108 does not require power from the separate power source 104 is particularly useful also for detecting peak acceleration of certain types of munitions, for example artillery munitions, as typically the peak acceleration of an artillery munition occurs before the separate power source 104 of the munition is fully activated.

[0056] A sensing axis of the sensor 108 is aligned with a main (e.g. longitudinal) acceleration axis of the munition such as to generate a graduated output proportional to the applied strain. The strain, in turn, is proportional to the magnitude of acceleration of the munition.

[0057] FIG. 2 schematically depicts an arming circuit, in accordance with an example embodiment. It will be appreciated that the arming circuit 200 of FIG. 2 is the same as the arming circuit 102 of FIG. 1. The arming circuit 200 comprises a sensor 208. Detailed description of the sensor 208 will be omitted as it will be appreciated that the sensor 208 of FIG. 2 is the same as the sensor 108 of FIG. 1.

[0058] A charge generated by the sensor 208 is converted to a voltage via the use of a capacitor 212. The capacitor behaves in a manner analogous to mathematical integration and thus the charge output from the setback event results in a distinct voltage magnitude being recorded on the capacitor 212. When a separate power source 204 (equivalent to the separate power source 104 of FIG. 1) becomes available later, the voltage on the capacitor 212 can be interrogated via a high impedance comparator circuit 214 and, if the voltage is of the correct magnitude, this can be used to indicate that a valid arming event has occurred. That is, the comparator circuit 214 is arranged to compare the voltage stored by the capacitor 212 with a threshold value. The output of the comparator circuit 218 is depicted schematically as output 206. The output 206 is equivalent to the output 106 of FIG. 1.

[0059] The arming circuit 200 further comprises a rectifier 216, located between the sensor 208 and the capacitor 212, intended to prevent charging under accelerations of the wrong polarity, thus further enhancing the safety of the fuze arming system, as accelerations of the wrong polarity will not be falsely interpreted as a setback event. In one example, the rectifier 216 comprises a rectifying diode. The arming circuit 200 also comprises a bleed resistor 218, connected in parallel with the capacitor 212, arranged to limit the storage time to a few tens of milliseconds and hence prevents potential interference and/or errors due to acceleration events experienced prior to firing, once again enhancing the safety of the fuze arming system.

[0060] While the magnitude of the integrated setback voltage stored by the capacitor 212 has so far been described as used for indicating that a setback event has occurred, it will be appreciated that other uses are also possible. In one example, the charge generated by the sensor 208 is converted by the capacitor 212 in order to produce a graduated output. For example, the magnitude of the integrated setback voltage may be used to provide information on the prevailing launch conditions, such as charge increment which might or relate to an equivalent approximate muzzle velocity. This graduated voltage output can be used to actively manage factors such as post-launch arming delay to allow safe separation distance to be relatively independent of charge increment, shell type, and other such factors. In one embodiment, the graduated output is used for arming a fuze, and/or programming a fuze. The provision of such graduated voltage output further improves the safety of the fuze arming system.

[0061] FIG. 3 schematically depicts a munition comprising the fuze arming system, in accordance with an example embodiment. The munition 300 comprises an explosive charge 301, a fuze 302, and a fuze arming system 303. The fuze arming system 303 is equivalent to the fuze arming system 100 of FIG. 1. The explosive charge 301 is activated by the fuze 302, causing the ammunition effectfor example, in case of the munition 300 being an artillery round, the exploding thereof. The fuze 302 is the detonator of the explosive charge 301. The fuze arming system 303 is arranged to produce an output indicating that an arming event has occurred in order to enable the fuze 302 to be armed, or to arm the fuze 302 directly. The munition 300 comprises (but is not limited to) artillery shells and charges, missiles, rockets, and mortar rounds, as well as small arms munitions such as bullets.

[0062] FIG. 4 schematically depicts a fuze arming method for a munition, in accordance with an example embodiment. In step 401, the method comprises detecting a setback event. As explained above in relation to FIG. 1, the setback force is the rearward force of inertia resulting from the forward acceleration of a projectile (in this case, a munition) during its launching phase, applied in the direction along of the path of travel of the projectile. That is, the setback force is the force generated as the munition is initially accelerated. At least two separate environments must be detected in order to permit arming. Mechanical artillery fuzes typically use separate, independent mechanisms to detect setback and spin. Rotational arming requires that a munition reaches a certain rpm before an arming event occurs. Thus, by detecting a setback event, and using that to indicate that an arming event has occurred, earlier arming might be achieved, which is beneficial in situation where early arming is requiredfor example, when the munition has a relatively short distance to travel to the target. In step 402, the method comprises the step of, in response the setback event being detected, generating a signal that an arming event has occurred. An arming event is understood as an event representing a point in time at which the fuze may be armed; for example, the munition reaching its peak acceleration. In step 403, the method comprises the step of, in response to the setback event occurring in response to the setback event occurring, producing a graduated output, and using that graduated output. Such graduated output is produced by the sensor before an external power source (that is, a power source used to power components of the munition, separate from the sensor) becomes available, allowing for earlier detection of an arming event. This does not necessarily mean that the fuze can trigger an explosive charge, based on the detection of the setback event, and/or generation of the signal indicating that the arming event has occurred. Other conditions may need to be met. Important is that the generation of the signal indicating that the arming event has occurred may occur before the power source of the fuze is fully activated.

[0063] As above, this all means that the sensor is effectively acting as a form of short-term memory, for use in programming post-launch functionality. The sensor is able to provide self-powered signals, and so information and context, about a launch, for use in detecting launch and setting post-launch conditions. This may allow for better safety, but also better target engagement (more accurate, reliable, or simpler implementation). Also, any accumulated energy is used for such detection, programming, and so on, and not necessarily for powering the munition. This means that a discharge route for the accumulated energy (e.g. used in processing the signal) may be intentional, to avoid false triggers due to events immediately prior to loading of the munition. Since the munition may be more generally powered by a separate, main power source (separate to the charge-generating sensor), this could provide additional safety. For example, parts of the fuze controlling initiation may not be powered until after launch. All of this may allow for better compliance with safety standards, or better safety standards.

[0064] Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.