NO20240945A1 - - Google Patents

Description

METHOD AND SYSTEM FOR COUNTING NUMBER OF SHOTS FIRED FROM

A WEAPON

TECHNICAL FIELD

The invention relates to the field of weapons, and more specifically to a method and system for registering number of shots fired from a weapon while a trigger mechanism is activated.

BACKGROUND

There are different types of weapons ranging from small hand weapons to large and remotely operated weapons. How they operate depends on the type of weapon.

Manual or semi-automatic weapons shoot one shot each time a trigger is pulled. For a manual weapon, a user loads one bullet at a time before pulling a trigger firing the weapon. A semi-automatic weapon automatically loads a bullet that will be fired each time a trigger is pulled. Fully automatic weapons will release a burst of several shots while a trigger mechanism is activated. Activation of a trigger mechanism can be done manually or automatically.

For remote activation of a trigger mechanism of automatic weapons, electromagnetic induction generators with a movable plunger, such as solenoids, are typically used. For weapons with no inherent remote triggering by design, it is common to retrofit a solenoid to act on the weapons mechanical trigger mechanism. A solenoid is typically mounted close to a trigger mechanism such that when powered, a plunger will move from a retracted position when the solenoid is in a de -energized state to an extracted position when the solenoid is in an energized state, thereby activating the trigger mechanism of the weapon. For an automatic weapon a burst of shots is fired during continuous activation of the solenoid.

Reliable counting of the number of shots fired from an automatic weapon when firing a series of shots has been difficult to do in a reliable manner. Previous methods include using microphones to listen for sound impulses, where each impulse indicates a shot. This is however sensitive to nearby sound sources that may affect counting. Optical gyroscopes and accelerometers detecting vibrations and movements of a weapon, or a weapon mount are also used as means for counting a series of shots fired.

US 7669356 B2 describes an example of using an accelerometer for detecting the number of shots fired from an automatic firearm. The device is attached to the firearm and detects recoils after each shot of the weapon.

Systems detecting movements or vibrations are sensitive to movements other than those caused solely by the recoil of an automatic weapon.

Yet another way of counting the number of shots fired in a series of shots is to detect light triggered by flashes from a weapon muzzle. This way of detection is not sensitive to movements or vibrations of the weapon but may detect additional flashes from other sources than the weapon it is meant to detect light flashes from.

Common methods for retrofitting and adding shot counting capabilities to weapons are prone to false triggering and may give unreliable readings.

The present solution suggests using a solenoid as both the activation device for a trigger mechanism of a weapon and a sensor for detecting if a shot has been fired, and for an automatic weapon, the actual number of shots fired while the trigger mechanism is activated. This means that no further modifications must be made to the weapon for registering shots.

SUMMARY OF THE INVENTION

The present invention is defined by the appended claims and in the following.

Automatic weapons fire a series of shots while a trigger mechanism is activated. The invention is defined by a system for registering number of shots fired while a trigger mechanism of a weapon is activated.

In general terms and in a first aspect of the invention, there is provided a system comprising a weapon and a solenoid with a movable plunger configured to activate a trigger mechanism of the weapon. A power supply is connected to an activation device and the activation device is connected to the solenoid. The trigger mechanism of the weapon comprises several cooperative devices integrated in a bolt assembly of the weapon. These devices are a firing pin driven by a driving spring, a cocking lever, a sear and a sear slide. When loaded, the driving spring is compressed and arranged to push the firing pin forward to hit the primer of a bullet. The driving spring is held back by a cocking lever mechanism until the driving spring is released. This occurs when the sear slide, also called the trigger, presses down the slide thereby releasing the firing pin.

In one embodiment, activation of the activation device powering the solenoid of the weapon is performed locally where the weapon is located. In another embodiment, activation is performed from a remote location. In this embodiment, the activation device comprises signal receiving means and a controller connected to the activation device. The activation device is then configured for receiving remote trigger signals for powering the solenoid.

The system comprises voltage and/or current measuring means configured to continuously measure voltage across the solenoid or current through the solenoid.

The system comprises signal detecting means configured to detect and register voltage or current signal fluctuations while the trigger mechanism is activated, i.e. while the solenoid is powered. Each fluctuation deviating from the applied voltage and current powering the solenoid is detected.

The system comprises counting means configured for counting detected signal fluctuations while the trigger mechanism is activated.

In one embodiment, at least one of: the activation device, the voltage and current measuring means, the signal detection means, or the counting means are integrated in the solenoid and/or the power supply cable of the solenoid or arranged as an in-line installation with the power supply cable. An in-line installation will have an input connected to the power supply cable, and an output connected to the coil of the solenoid. All these embodiments are suitable for retrofitting a solenoid to activate a trigger mechanism of an originally manually operated weapon.

In one embodiment, the system comprises signal conditioning means converting analogue voltage and/or current signals to digital signals. The signal conditioning means are in one embodiment integrated in the solenoid. In another embodiment, the signal conditioning means are integrated in a power supply cable of the solenoid, or as an in-line installation with the power supply cable. In yet another embodiment, one part of the signal conditioning means is integrated in the solenoid while another part of the signal conditioning means is integrated in the power supply cable or as an in-line installation.

The system comprises presenting means configured for presenting number of shots fired in the series of shots based on counted number of signal fluctuations. The presenting means can be a display showing the number of shots fired and/or number of shots left. The presenting means can in another embodiment be verbally presented through a speaker.

In a second aspect of the invention, there is provided a method for registering number of shots fired while a trigger mechanism of a weapon is activated. A solenoid with a movable plunger is configured to activate a trigger mechanism of the weapon. The solenoid is connected to an activation device powering the solenoid when activated.

The method comprises receiving a trigger signal in the activation device powering the solenoid. The movable plunger will then activate the trigger mechanism of the weapon.

The method comprises detecting voltage across the solenoid or current through the solenoid by the voltage and current measuring means.

The method comprises detecting and registering signal fluctuations of the voltage across the solenoid or current through the solenoid while the trigger mechanism of the weapon is activated by the signal detection means. Voltage fluctuations are detected as voltage signal pulses superimposed on the voltage powering the solenoid. Current fluctuations are detected as variations in supplied current powering the solenoid.

The method comprises counting number of signal pulses while the trigger mechanism is activated by the counting means.

In one embodiment, the time between each signal fluctuation is detected. A repeating pattern of fluctuations with a fixed time between each signal fluctuation is established. When this repeating pattern has been established, signal noise obscuring measurements in-between the repeating pattern of signal fluctuations are removed from the registered counted number of fluctuations. This is performed in the signal detecting means.

According to one embodiment, the time between each signal fluctuation detected during the series of shots from the automatic weapon is compared with time between each shot according to a rate of fire specified for the automatic weapon. By comparing the time between each signal fluctuation detected with the time between each shot, according to the rate of fire, signal pulses caused by noise occurring in -between expected signal fluctuations are removed from the registered counted number of signal fluctuations.

In one aspect of the method, detected signals are transformed to digital signals before being processed. In one aspect, an electrical frequency spectrum across the solenoid is analysed and filtered to amplify the expected signal frequency.

The method comprises presenting, by the presentation means, the number of shots fired in the series of shots or shots left based on counted number of signal pulses during activation of the trigger mechanism of the automatic weapon.

SHORT DESCRIPTION OF THE FIGURES

The present invention will be described in detail by reference to an example embodiment shown in the following figures, in which:

Figure 1 is an isometric view of an automated weapon actuated by a solenoid.

Figure 2 is an isometric and a cross-sectional view of a solenoid illustrating the operation principle.

Figure 3 is an isometric view of a section of the automated weapon showing arrangement of the bolt assembly.

Figure 4 illustrates details of the bolt assembly.

Figure 5 illustrates details of the mechanical interaction between a solenoid and a side trigger mechanism of a weapon.

Figure 6 illustrates the impact point between the bolt assembly and the solenoid and the devices controlling the solenoid.

Figure 7 is a graph illustrating displacement of the plunger of the solenoid when it is powered.

Figure 8 is a graph illustrating a resulting voltage signal where each recoil kick produces voltage signals superimposed on a voltage signal powering the solenoid.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described by examples and with reference to the accompanying figures illustrating an embodiment of the invention. These figures are provided to facilitate the understanding of the disclosed solution and shall not be considered limiting of the breadth, scope, or applicability thereof.

The invention comprises a method and system configured for registering number of shots fired while a trigger mechanism of a weapon is activated by a plunger of a solenoid.

This is achieved by detecting and registering voltage signal fluctuations across the solenoid or current signal fluctuations through the solenoid while the trigger mechanism is activated. Each signal fluctuation reflects a shot.

Figure 1 is an isometric view of an automated weapon 50 actuated by a solenoid 10. In this embodiment, the weapon 50 can be triggered for firing a series of shots by activating and powering the solenoid 10.

Figure 2 is an isometric view and a cross-sectional view of a solenoid 10 illustrating the operating principle. The solenoid 10 is a tubular construction made by a wound conducting coil 20 placed inside a housing 15. A plunger 24 with a ferromagnetic core is placed inside the wound conducting coil 20. Power is provided to the conducting coil 20 through connected power pins 22 installed in the wall of the housing 15. Generally, when powered, the plunger 24 will be pulled to the centre of the coil 20. Depending on the arrangement of the movable plunger 24 and the electric coil 20 in the housing 15, the plunger 24 will either be pulled to an inner position 28 or pushed to an outer position 29. The movement of the plunger 24 is due to an electric force produced by the interaction between the electric coil 20 and a generated electric field, which is a known induction principle. The plunger 24 of the solenoid 10 used for activating the trigger mechanism of the weapon 50 is pushed out from the housing 15 when powered and pulled into the housing 15 by a plunger spring 26 inside the solenoid 10 when not powered.

Figure 3 is an isometric view of a section of the weapon 50 showing an arrangement of the bolt assembly 60. During firing of the weapon 50, the bolt assembly 60 moves between a rear and a front position of the weapon 50. When in the front position, a firing pin of the bolt assembly 60 is loaded by a spring inside the bolt assembly 60. When a trigger mechanism is activated the firing pin is pushed forward until it hits a primer of a bullet which then is fired. The recoil of the weapon 50 will push the bolt assembly 60 back to the rear position and in the same motion charge the charging lever 68 loading the firing pin by means of mechanical interaction between charging lever 68 and the housing of the weapon 50, ejecting the spent bullet casing and feeding a new bullet to the bolt assembly 60. The movement is halted and reversed by a spring 70 and pushed forward to the front position. This cycle of movements is repeated while the trigger mechanism is activated, and ammunition is present to feed the cycle.

Figure 4 illustrates details of the bolt assembly 60. A feed and ejector mechanism working in conjunction to the movement of the bolt assembly 60 enabling ejecting empty shells from the fired weapon 50 and inserting new ammunition into the barrel of the weapon 50 is well known and is outside the scope of this invention. The trigger mechanism comprises a sear slide 64 that when pushed into the bolt assembly 60 presses down a sear 66 which will release the firing pin hitting the primer of a bullet that then will fire.

Figure 5 illustrates details of the mechanical interaction between a solenoid 10 and a side trigger mechanism of the automatic weapon 50. The solenoid 10 is the activating device for a trigger mechanism of the weapon 50. The solenoid 10 is mounted to the side of the weapon 50 such that its plunger 24 is close to a sear slide 64 of the trigger mechanism of the bolt assembly 60 of the weapon 50. When the solenoid 10 is powered, the plunger 24 will move to an outer position 29 pushing the sear slide 64 triggering the weapon 50.

Figure 5 shows that the bolt assembly 60 is in the front position, i.e. the firing pin is loaded and ready to be released for firing the weapon 50 when the triggering mechanism is activated by the plunger 24 of the solenoid 10. After firing, the bolt assembly will be pushed back to the rear position while the movement is dampened by the driving spring 70, which will be compressed and in turn push the bolt assembly 60 to the front position.

Figure 6 illustrates the different means arranged to activate the trigger mechanism of the weapon 50 as well as the mechanical interaction and the impact point 40 between the sear slide 64 of the bolt assembly 60 and the solenoid 10. When the solenoid 10 is powered via the power pins 22, the plunger 24 of the solenoid 10 moves to the outer position 29, ref. fig.2. As a result, the plunger 24 will push the sear slide 64 into the bolt assembly 60. The sear slide 64 will then activate the trigger mechanism by pushing down the sear 66 of the weapon 50 that will fire a series of shots until the plunger 24 is pulled back into the solenoid 10. During the series of shots fired, the bolt assembly 60 will move between its front and rear positions. Each time the bolt assembly 60 moves forward to the front position, the sear slide 64 will hit the plunger 24, as illustrated by the impact point 40 in fig. 6. The impact depresses the sear slide 64 triggering the weapon 50. This impact to the angled face of the end of the plunger 24 will produce detectable fluctuation signals in the power supplied to the solenoid 10 by exerting a force to the plunger 24 forcing the plunger 24 against the applied magnetic field created by the coil 20.

Figure 6 shows a power supply 30, e.g. a battery, connected to an activation device 32. The activation device 32 will power to the solenoid 10 when the activation device 23 is activated. In one embodiment, the activation device 32 comprises a switch that when pressed activates the activation device 32. In another embodiment, the activation device 32 comprises signal receiving means and a controller configured for receiving remote trigger signals activating the activating device 32 which then will power the solenoid 10. The plunger 24 of the solenoid 10 will move to the outer position 29 while the solenoid 10 is powered from the activation device 32.

The voltage and/or current supplied to the solenoid 10 are measured by voltage and current measuring means 33. Signal detection means 34 detects fluctuations in the supplied voltage or current. Each fluctuation will be detected and counted by counting means 35. Voltage fluctuations are detected as voltage pulses superimposed on the voltage powering the solenoid 10. Current fluctuations are detected as variations in supplied current powering the solenoid 10. Each voltage or current fluctuation represents a shot fired, and the number of shots fired in a series of shots is presented by presenting means 36. The signal detection means 34 may comprise signal conditioning means and be an integrated part of the solenoid 10. It may also be retrofitted to a power cable powering the solenoid 10. The signal detection means 34 may in one embodiment convert analogue signals to digital signals.

Figure 7 is a graph illustrating displacement of the plunger 24 of the solenoid 10 when it is powered and activated. The plot shows two graphs A and B. Graph A represents the voltage across the solenoid 10 and graph B represents the displacement of the plunger 24. The solenoid 10 is powered after 0.2s. The voltage rises rapidly to just above 20V and stabilizes at about 20V when the coil 20 is fully energized and the plunger 24 becomes stationary at a fully extended outer position 29 pushing and activating the sear slide 64 of the trigger mechanism. When the activation device 32 turns off the power after about 1.5s, the voltage drops rapidly to a negative value before returning to 0V, as shown in voltage graph A. This is due to a separate electrical circuit dissipating the induced magnetic field in the coil 20 as quickly as possible when de-energized. This falls outside of the scope of this invention and will not be addressed further. When the plunger 24 comes to rest, the trigger mechanism of the automatic weapon 50 has been activated for about 1.3s. During this time, the bolt assembly 60 has, for a series of shots fired, cycled between the front and the rear positions.

As mentioned, the bolt assembly 60 will be pushed back from the front position to the back position by the recoil of the weapon 50 when firing. When the bolt assembly 60 passes the fully extended plunger 24, the sear slide 64 of the bolt assembly 60 will hit the plunger 24 each time. This impact will push the plunger 24 slightly back into the solenoid 10, against its applied magnetic force before returning to the outer position 29. This movement will produce an electromagnetic voltage with an opposite polarity than the polarity of the voltage powering the solenoid 10 and pushing the plunger 24 out of the solenoid 10. As a result, the voltage across the solenoid 10 will drop for a short time before the plunger 24 returns to its outer position 29. This action is seen as voltage fluctuations. The drops in voltage are detected as signal pulses superimposed on the voltage powering the solenoid 10.

Likewise, the current powering the solenoid 10 will, during the movement of the plunger 24 to the impact point 40, for a short time be disrupted. As a result, the current will be reduced for a short time, shown as fluctuations in the current powering the solenoid 10.

Fluctuations in voltage and current due to small movements of the plunger 24 is detected by the signal detecting means 34. Each voltage or current fluctuation represent a shot fired from the automatic weapon 50. This means that the solution can be used for detecting if a single shot has been fired during activation of the trigger mechanism, and the number of shots fired if a series of shots has been fired during activation of the trigger mechanism.

Figure 8 is a graph illustrating a resulting voltage signal where each recoil kick of an automatic weapon 50, during a series of shots fired, produces voltage signals superimposed on the voltage powering the solenoid. The figure shows that the solenoid 10 is activated with about 17.61V for about 3.9s. During this time, four signal pulses are detected, meaning that the plunger 24 is hit four times by the sear slide 64 of the bolt assembly 60. This in turn means that a series of four shots has been fired during the period the solenoid 10 has been powered and activated.

The solution presented herein provides a method for using a solenoid 10 for activating a trigger mechanism of a weapon 50 as well as a sensor for detecting the number of shots fired in a series of shots. This means that existing weapons provided with a solenoid for activating the weapon can easily be equipped with signal detecting means and presenting means connected to the solenoid for keeping track of shots fired or shots left for firing. Retrofitting of a solenoid and the system disclosed herein is also feasible for originally manually operated weapons without a solenoid.

List of references

10 – solenoid

15 – housing

20 – coil

22 – power pins

24 – plunger

26 – plunger spring

28 – inner position

29 – outer position

30 – power supply

32 – activation device

33 – voltage and current measuring means

34 – signal detecting means

35 – counting means

36 – presenting means

40 – impact point

50 – weapon

60 – bolt assembly

62 – cocking lever

64 – sear slide

66 – sear

70 – driving spring

Claims (13)

1. A system for registering number of shots fired while a trigger mechanism of a weapon (50) is activated thereby firing one or more shots,

the system comprises:

- the weapon (50) and a solenoid (10) with a movable plunger (24) configured to activate a trigger mechanism of the weapon (50);

- a power supply (30) connected to an activation device (32) which is connected to the solenoid (10);

- voltage and current measuring means (33) configured to continuously measure voltage across the solenoid (10) or current through the solenoid (10);

- signal detecting means (34) configured for detecting and registering voltage or current signal fluctuations while the trigger mechanism is activated;

- counting means (35) configured for counting detected signal fluctuations while the trigger mechanism is activated;

- presenting means (36) configured for presenting number of shots fired based on counted number of signal fluctuations.

2. The system according to claim 1, comprising signal receiving means and a controller connected to the activation device (32) configured for receiving remote trigger signals activating the solenoid (10).

3. The system according to claim 1 or 2, wherein at least one of the activation device (32), the voltage and current measuring means (33), the signal detection means (34), or the counting means (35) are integrated in the solenoid (10).

4. The system according to claim 1 or 2, wherein at least one of the activation device (32), the voltage and current measuring means (33), the signal detection means (34), or the counting means (35) are integrated in a power supply cable of the solenoid (10) or arranged in-line with the power supply cable.

5. The system according to claims 1 or 2, wherein the signal detection means (34) are integrated in a power supply cable of the solenoid or arranged inline with the power supply cable.

6. The system according to any of the previous claims, comprising signal conditioning means converting analogue voltage and/or current signals to digital signals.

7. The system according to claim 6, wherein the signal conditioning means are integrated in the solenoid (10) or in a power supply cable of the solenoid (10) or arranged in-line with the power supply cable.

8. A method of registering number of shots fired while a trigger mechanism of a weapon (50) is activated, the method comprises:

- receiving a trigger signal in an activation device (32) enabling powering of a solenoid (10) with a movable plunger (24) configured to activate the trigger mechanism of the weapon (50);

- detecting voltage across the solenoid (10) or current through the solenoid (10) by voltage and current measuring means (33);

- detecting and registering voltage or current signal fluctuations while the trigger mechanism is activated by signal detection means (34);

- counting number of detected signal fluctuations while the trigger mechanism is activated by counting means (35);

- presenting number of shots fired based on counted number of signal fluctuations by presentation means (36).

9. The method according to claim 8, wherein time between each signal fluctuation is detected.

10. The method according to claim 9, wherein a repeating pattern of fluctuations with fixed time between each signal fluctuation is established, wherein signal noise obscuring measurement in-between the repeating pattern of signal fluctuations are removed from the registered counted fluctuations.

11. The method according to claim 9, wherein the time between each signal fluctuation detected during the series of shots is compared with time between each shot according to a rate of fire specified for an automatic weapon, wherein signal pulses caused by noise occurring in-between expected signal fluctuations, according to the rate of fire specified for the automatic weapon, are removed from the counted number of registered counted fluctuations.

12. The method according to any of the claims 8 to 11, wherein detected signals are transformed to digital signals before being processed.

13. The method according to any of the claims 8 to 12, where an electrical frequency spectrum across the solenoid is analysed and filtered to amplify the expected signal frequency.