WO2014076357A1

WO2014076357A1 - Device to control the exhaust of propellant gas from a firearm

Info

Publication number: WO2014076357A1
Application number: PCT/FI2012/051125
Authority: WO
Inventors: Jarno PIETILÄ
Original assignee: Sako Oy
Priority date: 2012-11-15
Filing date: 2012-11-15
Publication date: 2014-05-22

Abstract

A device (6) for a firearm (7) to control the exhaust of the propellant gas flow from the firearm muzzle (71). The device (6) comprises an exit aperture (60) formed as a flow nozzle having a trailing edge (62) which is formed to comprise a number of V-shaped notches (64). Invention relates also to a firearm suppressor (1) comprising a suppressor housing (10) defining the outer surface of the suppressor (1), an interior arranged to form a number of compartments (30), mounting means (2) for fastening / detaching the suppressor with a barrel (70) of the firearm (7) and having an aperture (2) for a projectile (8) and propellant gases of the firearm (7) to enter to the interior of the suppressor (1), an exit aperture (60) for the projectile (8) and the propellant gases to exit the suppressor (1). The exit aperture (60) is formed as a flow nozzle having a trailing edge (62) which is formed to comprise a number of V-shaped notches (64).

Description

Device to control the exhaust of propellant gas from a firearm

[001 ] The present invention relates to a device for a firearm to control the exhaust of the propellant gas flow from the firearm muzzle. The present invention relates also to a firearm suppressor comprising:

- a suppressor housing defining the outer surface of the suppressor,

- an interior arranged to form a number of compartments,

- mounting means for fastening / detaching the suppressor with a barrel of the firearm and having an aperture for a projectile and propellant gases of the firearm to enter to the interior of the suppressor,

- an exit aperture for the projectile and the propellant gases to exit the suppressor.

The present invention relates also a firearm comprising a device to control the exhaust of the propellant gas flow from the firearm muzzle and a firearm comprising said suppressor. [002] In the field of noise and flash reduction of firearms there has presented quite many different constructions and devices for the same purpose i.e. to dampen the noise and flash caused by the rapidly burning of propellants when the firearm is fired. As the benefits of this reduction are quite obvious, the noise of undamped firearm may exceed 130 dB, even 160 dB, and can be harmfull for firearm users or anyone nearby and disturb large surrounding areas, for example by a hunting area or by a shooting range. It is also preferred to be avoided or at least minimized in military applications where the sound of the firing immediately attracts the attention of parties concerned. The better the suppressor is in terms of noise reduction and if combined to easy or simple manufacturability, the better the suppressor is in terms of commercial interest.

[003] A firearm bullet or in general a projectile, is rapidly accelerated at firing to an initial velocity of 300 to 1 100 m/s depending the type of the firearm. The initial velocity means here the velocity of the projectile when it exits the barrel or corresponding part of a firearm. This means that the initial velocity may be within range of about 0,8 to 3,3 Mach (where 1 Mach is the speed of the sound when the medium is normal athmospheric air in about normal temperature and pressure (ntp)). Thus the flow dynamics range conserned may vary from slightly subsonic to highly supersonic flows. [004] In case of supersonic noise dampening, the suppressor is not capable of reducing the noise originating from the projectile breaking the sound barrier during the flight to a destination. Thus the aim of the suppressor is to reduce as much as possible the noise generated by the phase when the bullet is no longer in front of that high pressure gas and the pressure is rapidly normalizing to an athmospheric pressure, the burning propellant is exiting the barrel and when the propellant residuals are burning outside the barrel.

[005] From the state of the art it is know various of different constructions, but the science behind the theory is still in some extent unknown. One rather re- cent publication is EP 2 191 233 B1 , which presents one theory and a firearm suppressor applying that theory. The construction shows a suppressor comprising a number of mixer/ejector type nozzles located within the suppressor housing and that the suppressor housing is provided with vent holes for providing ambient air to mixed with propellant gases at the nozzles. [006] From the state of the art it is also known EP 0 660 915 B1 , which presents a firearm suppressor that can be adapted for use with a wide range of ammunition types by virtue of the following features: an adapter designed to be attached to the mouth of the barrel; an end-piece forming the mouth of the silencer, with an aperture designed to allow the projectile to pass out; a central element, located between the adapter and the end-piece, with a number of compartments disposed one behind the other in a straight line, each compartment having an aperture designed to allow the projectile to pass through; each compartment being attached in modular fashion to the next compartment and the outer walls of the series of compartments forming the outer wall of the si- lencer.

[007] From the state of the art it is also know US7905170B1 , which presents a flash suppressor. The body of the flash suppressor surrounding the exit chamber has three equally-spaced 45 degree angled cuts or transition portions running the length of exit chamber and angled forward toward three slots defined in a forward portion of the flash suppressor. Transition portions have radius ends at their proximal ends and are open at their distal ends, thereby defining a concave profile, having three adjacent slots deflector cones for guiding the gas flow. [008] The objective of the present invention is to provide a device for firearm capable of reducing noise caused by firing of a firearm. As the flow dynamics of the erupting propellant gases from the firearm is rather complicated chain of phenomenon, the invention aims to offer a device to be mounted on the muz- zle of a firearm for reducing the noise as such or as a combination with a suppressor.

[009] One aspect of the present invention is characterized in that the device comprises an exit aperture formed as a flow nozzle having a trailing edge which is formed to comprise a number of V-shaped notches. [010] Another aspect of the present invention is a firearm suppressor characterized in that the exit aperture is formed as a flow nozzle having a trailing edge which is formed to comprise a number of V-shaped notches.

[01 1 ] Still an aspect of the present invention is a firearm comprising such device and still an other aspect is a firearm comprising such suppressor. [012] The device for a firearm to control the exhaust of the propellant gas flow from the firearm muzzle, which device comprises an exit aperture formed as a flow nozzle having a trailing edge which is formed to comprise a number of V- shaped notches. The purpose of this trailing edge is to break the formation of the pressure wave and turn the large scale turbulence into small scale turbu- lence, thus decreasing the peak values of that pressure i.e. sound pressure level. The applicant has noted that this flow nozzle type construction has a signifficant effect on the propellant gas exhaust from the muzzle and thus it reduces the noise in some extent. Naturally with the plain muzzle mounting the effect in noise reduction is limited, but when mounted to a conventional or in general any suppressor, the effect is even better. This may be due to a prolonging effect of suppressor for the gas flow out from the suppressor housing. However, since this type of supersonic flows are not very well studied in all applications and they are rather complicated to simulate in theroretical level, the applicant is not bound to this theory. [013] According to one embodiment of the invention the V-shaped notches are arranged to open in the direction parallel to the projectile path. Thus the V- shape is divergent in the same direction as the main direction of the flow. With this feature the propellant gas flow just about to begin to expand in the ambient athmosphere still has partially some steering surface around and partially di- verging openings in between, to start the residuals burning in athmosphere and hot gases to expand.

[014] According to one embodiment the number of V-shaped notches is 8. According to still another embodiment the number of V-shaped notches is 6. These numbers of V-shaped notches located on the circumference of the trailing edge are noticed to work particularly well in this application. Naturally also some other number of V-shaped notches may also work.

[015] The flow nozzle V-shape has a V-angle within range of 30 to 60 degrees, preferably 45 degrees. These are also the design parameters that seem to work better than some other parameters. Also the flow nozzle V-shape has a bottom radius r smaller than 1 mm. This bottom radius may well be smaller than 1 mm, for example 0,5 mm, 0,2 mm or even 0,1 mm, but the limit of man- ufacturability comes close with these values. However this also differentiates the V-shape from an U-shape. There are plenty of flash suppressors having U- shaped channels like previously mentioned US7905170B1 . In general the U- shape has some kind of bottom radius of typically about 5 mm and the walls are parallel, not continuously divergent as it is with the V-shape.

[016] In the following the invention is disclosed in more detail in connection with the accompanying drawings where,

FIG. 1 presents an embodiment of a firearm comprising a suppressor,

FIG 2 presents an embodiment of a firearm comprising a device to control the exhaust of the propellant gas flow from the firearm muzzle,

FIG 3 presents an isometric view of an embodiment of the device,

FIG 4 presents a cross sectional view of an embodiment of the device,

FIG 5 presents a outer side view of the embodiment of Fig. 4,

FIG. 6 presents a suppressor.

[017] In Fig 1 it is presented a firearm 7 with a suppressor 1 comprising

- suppressor housing 10 defining the outer surface of the suppressor 1 ,

- an interior arranged to form a number of compartments (not shown),

- mounting means 2 for fastening / detaching the suppressor with a barrel 70 of the firearm and having an aperture for a projectile and propellant gases of the firearm to enter to the interior of the suppressor 1 ,

- an exit aperture 60 for the projectile and the propellant gases to exit the suppressor 1 , - the exit aperture 60 is formed as a flow nozzle having a trailing edge which is formed to comprise a number of V-shaped notches (the flow nozzle is not shown in Fig. 1 ).

[018] In Fig. 2 it is presented a firearm with a device 6 for a firearm 7 to control the exhaust of the propellant gas flow from the firearm muzzle 71 . The device comprises an exit aperture 60 formed as a flow nozzle having a trailing edge 62 which is formed to comprise a number of V-shaped notches 64.

[019] In Fig. 3 it is presented a device 6 for a firearm to control the exhaust of the propellant gas flow from the firearm muzzle. The device comprises an exit aperture 60 formed as a flow nozzle having a trailing edge 62 which is formed to comprise a number of V-shaped notches 64. The V-shaped notches 64 are arranged to open in the direction parallel to the projectile path PP (in Fig. 3 the arrowhead shows the direction of the advancing projectile). The device in Fig. 3 has eight V-shaped notches 64. This number could also be something else, like six notches is working also pretty well. The flow nozzle V-shape has an outer tip 65 comprising a sharp edge 651 at inner diameter and flat edge 652 at outer diameter thus forming a triangular in a plane about perpendicular to the projectile path.

[020] Fig 4 shows a side cross sectional view along the projectile path PP of one embodiment of the device 6. The flow nozzle V-shape has a V-angle Θ within range of 30 to 60 degrees, preferably 45 degrees. In V-shape the bottom in is shaped so that the flow nozzle V-shape has a bottom radius r smaller than 1 mm. It is not intended that the bottom radius r is too large and thus the V-shape notch would turn to a U-shaped notch. The trailing edge 62 of the V- shaped notches 64 are preferably rather sharp in shape so that the flow

[021 ] Suitably the exit aperture 60 diameter d is selected according to the firearm caliber by increasing the projectile diameter by about +10%. Thus the projectile has some clearance to the aperture walls of the device, it is highly unwanted that the projectile touches the device during the flight inside the device - it negatively affects the accuracy of the firearm immediately.

[022] In Fig 5 it is shown a outer view of the device of Fig. 4. In this embodiment the outer diameter is formed as a mounting surface 67, comprising for example a outer thread connectable to an inner thread at the end of a firearm suppressor. If the device is intended as a stand alone mounting for a firearm muzzle, a normal suppressor type inner thread at the device would be among preferable embodiments. Thus the device is a flow nozzle interchangeably mountable to the suppressor 1 or to a firearm 7.

[023] In Fig. 6 it is still presented an embodiment wherein the device 6 has been mounted as the exit aperture 60 of a firearm suppressor. The suppressor 1 comprises a suppressor housing 10 defining the outer surface of the suppressor 1 , an interior arranged to form a number of compartments 30 (for example 3 to 12 compartments, which are separated by baffles 3), mounting means 2 for fastening / detaching the suppressor with a barrel 70 of the fire- arm and having an aperture for a projectile 8 and propellant gases of the firearm to enter to the interior of the suppressor 1 , an exit aperture 60 for the projectile and the propellant gases to exit the suppressor 1 , the exit aperture 60 is formed as a flow nozzle having a trailing edge which is formed to comprise a number of V-shaped notches. [024] As evident to those skilled in the art, the invention and its embodiments are not limited to the above-described embodiment examples. Expressions representing the existence of characteristics, such as "the device comprises an exit aperture", are non-restrictive such that the description of characteristics does not exclude or prerequisite the existence of such other characteristics which are not presented in the independent or dependent claims.

[025] Reference numbers in figures:

1 suppressor

10 housing

2 mounting means

3 baffle

30 compartment

6 exit aperture flow nozzle 60 exit aperture

62 trailing edge

64 V-shaped notch

r botton radius of V-shaped notch

Θ V-angle

65 outer tip

651 sharp edge

652 flat edge

67 mounting surface

7 firearm

70 firearm barrel

71 firearm muzzle

8 projectile

PP projectile path

d diameter

Claims

Patentclaims

1 . A device (6) for a firearm (7) to control the exhaust of the propellant gas flow from the firearm muzzle (71 ), characterized in that, the device (6) comprises an exit aperture (60) formed as a flow nozzle having a trailing edge (62) which is formed to comprise a number of V-shaped notches (64).

2. The device (6) of patent claim 1 , characterized in that, the V-shaped notches (64) are arranged to open in the direction parallel to the projectile path (PP).

3. The device (6) of patent claim 1 , characterized in that, the number of V- shaped notches (64) is eight.

4. The device (6) of patent claim 1 , characterized in that, the number of V- shaped notches (64) is six.

5. The device (6) of patent claim 1 , characterized in that, the flow nozzle V- shape has a V-angle (Θ) within range of 30 to 60 degrees, preferably 45 de- grees.

6. The device (6) of patent claim 1 , characterized in that, the flow nozzle V- shape has a bottom radius (r) smaller than 1 mm.

7. The device (6) of patent claim 1 , characterized in that, the flow nozzle V- shape has a outer tip (65) comprising a sharp edge (651 ) at inner diameter and flat edge (652) at outer diameter thus forming a triangular in a plane perpendicular to the projectile path.

8. A firearm suppressor (1 ) comprising

- suppressor housing (10) defining the outer surface of the suppressor (1 ),

- an interior arranged to form a number of compartments (30),

- mounting means (2) for fastening / detaching the suppressor with a barrel (70) of the firearm (7) and having an aperture (2) for a projectile (8) and propellant gases of the firearm (7) to enter to the interior of the suppressor (1 ),

- an exit aperture (60) for the projectile (8) and the propellant gases to exit the suppressor (1 ),

characterized in that,

the exit aperture (60) is formed as a flow nozzle having a trailing edge (62) which is formed to comprise a number of V-shaped notches (64).

9. The suppressor (1 ) of patent claim 8, characterized in that the number of compartments (30), which are separated by baffles (3), is 3 to 12 compartments (30).

10. The suppressor (1 ) of patent claim 8, characterized in that, the V-shaped notches (64) are arranged to open in the direction parallel to the projectile path

(PP).

1 1 . The suppressor (1 ) of patent claim 8, characterized in that, the number of V-shaped notches (64) is 8 or 6.

12. The suppressor (1 ) of patent claim 8, characterized in that, the flow nozzle V-shape has a V-angle (Θ) within range of 30 to 60 degrees, preferably

45 degrees.

13. The suppressor (1 ) of patent claim 8, characterized in that, the flow nozzle is interchangeably mountable to the suppressor (1 ).

14. A firearm (7) comprising a device (6) according to claim 1 .

15. A firearm (7) comprising a suppressor (1 ) according to claim 8.