GUN SILENCER

Abstract: The invention relates to a gun silencer, which comprises an essentially cylindrical jacket (17). The jacket (17), together with the barrel (13) of the gun (11) delimits an expansion chamber (16), into which the combustion gases released from the mouth of the barrel (13) are arranged to discharge, in order to attenuate the sound of the shot. The silencer (10) further includes a deflector cone (21) and an end piece that reflects the combustion gases. Most of the expansion chamber (16) is arranged backwards from the mouth of the barrel (13). The silencer (10) also includes a guide cone (20), which is set around the mouth of the barrel (13) and expands forwards from it and extends coaxially around the deflector cone (21). In the guide cone (20), there are also holes (22), to guide the combustion gases outside the guide cone (20).

Description: GUN SILENCER The present invention relates to a gun silencer, which comprises an essentially cylindrical jacket, and which is intended to be detachably attached particularly to the end of the barrel of a high-pressure gun, such as a rifle, and additionally partly round the barrel parallel it to, and into the expansion chamber delimited by which jacket and barrel are the combustion gases released from the mouth of the barrel after the bullet in connection with the shot arranged to discharge, in order to attenuate the sound of the shot, the silencer further including a deflector cone being arranged in front of the barrel to deflect the combustion gases from the trajectory of the bullet into the expansion chamber, which is restricted, at least in front, by an end piece that reflects the combustion gases. Silencers are used especially in connection with high-pressure guns, because in these the sound of firing is, in many situations, too loud. Generally, guns with a caliber of 0.222 and greater are classified as high-pressure. Known silencers are tubular constructions that fit over the end of the barrel of the gun. For attachment, there is usually an external thread in the barrel, with a corresponding internal thread in the silencer. Inside a tubular silencer, there are several baffles, through the central hole in which the bullet can travel. The baffles form small chambers inside the silencer. As the bullet closes one baffle at a time, the combustion gases remain to swirl in the chamber thus formed. Alternatively, there may be small holes in the baffles, from which the combustion gases can flow to the adjacent chamber. This is meant to prevent the overloading of the chambers and at the same time to improve the effectiveness of the silencer. In the chambers, the pressure and velocity of the combustion gases diminish. In this case, once the bullet has travelled through the whole silencer, the reduced pressure discharges through the silencer. Thus, the sound of firing is partly attenuated. To maximize the attenuation, an attempt is made to create as many chambers as possible in the silencer. The chambers then become very small. In addition, the baffles are usually attached by welding. Thus, the silencer cannot be opened, so that it is almost impossible to clean it. Gradually, the small chambers and the holes between them become blocked with dirt, in which case there is insufficient discharge space. This can result in the silencer being broken and becoming detached. Furthermore, it is difficult to arrange several baffles precisely in the trajectory of the bullet, which affects the accuracy of the gun' s aim. The fact that the silencer is only attached at one end also reduces the accuracy of aim. To avoid poor balance, some silencers also extend backwards from the end of the barrel, i.e. partly round the barrel. In such cases, in addition to the baffles, there is also an expansion space formed by two pipes, one inside the other, into which the combustion gases can discharge. This construction makes the silencer even more complicated than before. In addition, the combustion gases swirl uncontrollably inside the silencer, despite a separate deflector cone, which has a detrimental effect on the trajectory of the bullet. The silencer also cannot be opened, while the pressure of the combustion gases stresses the end piece. Such a silencer is disclosed in Finnish patent number 85307. The invention is intended to create a new kind of gun silencer, which does not have a detrimental effect on the accuracy of the aim of the gun, but which not only silences the sound but also effectively attenuates the recoil of the gun. The characteris- tic features of the present invention appear in the accompanying Claims. In the silencer according to the invention, the combustion gases are directed to turn, in a controlled manner, rapidly in the opposite direction to the direction of travel of the bullet, so that the force then created reduces the recoil of the gun. Though the change in direction of movement is rapid, it takes place in stages, to reduce the impulse loading the construction. The real effect is created by ensuring a continuous flow for the combustion gases, inside the silencer. At the same time, the sound is effectively reduced. In addition, the silencer according to the invention is composed of precisely dimensioned components, to that it can be dismantled and cleaned, without altering its properties. Further, most of the silencer is located behind the end of the barrel. Thus, the silencer does not significantly increase the imbalance of the gun. The silencer is also supported at two points, which ensures that the accuracy of the aim of the gun is retained. Thanks to its simple construction, the total weight of the silencer remains within the permitted limits, nor does it contain parts that are flexible or subject to wear. The simple parts can be manufactured economically, despite their precision, while the silencer can be assembled at its place of use, without special tools. As the sound and recoil diminish, the accuracy achieved by the shooter usually improves. This brings considerable advantages both when shooting game and in competitions on a shooting range. Correspondingly, beginners' prior fears are reduced, as the recoil is considerably less than usual. In the following, the invention is described with reference to the accompanying drawings, which illustrate some embodiments of the invention, in which Figure 1 shows a silencer according to the invention attached to a shooter' s gun, Figure 2a shows a side view of a silencer according to the invention, in partial cross-section, with a bullet emerging from the barrel, Figure 2b shows the silencer of Figure 2a a moment later, Figures 3a and 4a show an exploded side view of the structural components of a silencer according to the invention, Figures 3b, 4b-4d show part of the structural components of Figures 3a and 4a in a front view, Figure 5a shows a side view of another silencer according to the invention when assembled and in partial cross- section, when the bullet emerges from the silencer, Figure 5b shows an exploded view of the end-piece of the silencer of Figure 5a and the components to be fitted over it. Figure 1 shows silencer 10 according to the invention attached to a rifle 11. Usually, telescopic sights 12 are used with the silencer. The silencer 10, which is thicker than the barrel 13, does not, however, interfere with aiming, especially when higher mounting bases are used for the sights. The silencer according to the invention can be attached to nearly all kinds of guns, though the attenuation achieved with it is particularly significant in the case of high-pressure guns, such as rifles. In high-pressure guns, the pressure of the combustion gases discharging from the mouth of the barrel is about 600 bar. The pressure is naturally dependent on the charge in the cartridge. The range of such guns is great, so that the silencer should affect the flight of the bullet as little as possible, preferably not at all. Figure 2a shows the gun silencer assembled and attached to the barrel 13, when bullet 14 comes out of barrel 13 after firing. Figure 2b shows the same situation a moment later. Barrel 13 is only shown in part. Silencer 10 includes a cylindrical jacket 17, which, with barrel 13, delimits an expansion chamber 16. Unlike in the state of the art, expansion chamber 16 is arranged backwards from the mouth of barrel 13. Thus, the silencer has practically no effect on the length of the gun 11. In addition, silencer 10 includes a guide cone 20 set around the mouth of barrel 13. Guide cone 20 expands forwards and extends coaxially around deflector cone 21. There are also holes 22 in guide cone 20, to direct the combustion gases outside the guide cone. There may be a gap between the mouth of the barrel and the guide cone, which corresponds operationally to holes 22. In addition, guide cone 20, deflector cone 21, and the front end of the jacket 17 are arranged to create an opposing force to the recoil. In practice, this is implemented by arranging an effectively frontal surface area to the combustion gases discharging from the mouth of barrel 13 and turning the direction of movement of the combustion gases rapidly through 180°. Thus, not only is the sound caused by the shot attenuated, but also an opposing force to the recoil is created. In the embodiment example, jacket 17 is mainly formed by a special discharge pipe 15 and an end piece 19. The expansion chamber 16 is also delimited by the end formed in end piece 19 and seal component 23. Generally, the operation of the discharge pipe and at the same time of the whole silencer, is thus based on a rapid change, through 180 degrees, in the direction of flow of the combustion gases discharging from the mouth of the barrel, when a force in the opposite direction to the recoil, i.e. a recoil reducing force, in created. The recoil is also cancelled by the impact of the combustion gases against the frontal surfaces. Thanks to the large expansion chamber, a sufficiently large pressure difference is maintained, during the shot, between the mouth of the barrel and the rear end of the silencer. Thus, it is possible to maintain a rapid flow of combustion gases for the entire firing event, when a significant force arises from the change of direction of the combustion gases. To preserve the flow, the inner surface of the discharge pipe is smooth, with no protrusions. Thus, expansion chamber 16 is essentially backwards from the end of the barrel and is delimited mainly between discharge pipe 15 and barrel 13. Generally, at least 70 %, and preferably 75 - 85 % of the expansion chamber 16 of silencer 10 is behind the mouth of barrel 13. The same can be seen from Figure 1, which also shows end piece 19. Silencer 10 is attached to the end of barrel 13 by means of a collar 18. The structural components of the silencer are shown in greater detail in connection with Figures 3a and 4a, and the same reference numbers being used for functionally similar components. Both discharge pipe 15 and end piece 19 containing the deflector cone 21 and guide cone 20 are attached around collar 18. The holes 22 of the guide cone are formed radially and are aligned in one or more rows. The holes ensure that the operation of the silencer takes place in stages, but, on account of the great velocity of the firing event, the counter- force effect takes place in pulses. In the first stage, bullet 14 essentially closes the discharge route of the high-pressure combustion gases directly out of the silencer. Thus, the combustion gases travel from the holes 22 of guide cone 20 essentially to the side with the lower pressure. At the same time, the direction of travel of the combustion gases changes. Part of the combustion gases travel between deflector cone 21 and guide cone 20, as far as end piece 19, turning, however, towards discharge pipe 15. In Figures 2a and 2b, the movement of the combustion gases is shown by arrows. The combustion gases also have a route to deflector cone 21. This is not a problem, however, because the combustion gases do not reach it before bullet 14, as they have to travel over a complicated route with turns, unlike bullet 14. In addition, as bullet 14 progresses, the increase in the amount of gas rapidly increases the pressure in the end piece 19 of the silencer. This greater pressure forces the combustion gases, which always travel behind it, into the discharge pipe, in which there is a considerably lower pressure for the whole of the firing event. As bullet 14 continues to progress, it almost entirely closes the discharge route of the high-pressure combustion gases out of the silencer (Figure 2b) . For this purpose, a tubular component 33 is arranged extending backwards from end piece 19, by means of which the exit opening of the combustion gases is moved backwards. When bullet 14 closes tubular component 33, the rest of the high-pressure and high-velocity combustion gases are forced to turn to discharge pipe 15. The outer surface of tubular component 33 also forms an auxiliary cone, to direct the combustion gases outwards. Generally, the length of tubular component corresponds at least to the diameter of the aforesaid exit opening. The flow of the combustion gases remains rapid for the entire firing event, because the pressure difference between the mouth of barrel 13 and the rear end of silencer 10 is maintained. Due to this, the expansion chamber 16 delimited by discharge pipe 15 and barrel 13 is of a considerable size. Thus, the equalized pressure of the combustion gases in discharge pipe 15 inside the silencer remains relatively low, even less than 30 bar. The maintenance of the flows is also assisted by the size of the toroidal areas defined by the cones 20 and 21 and by deflector cone 21 and jacket 17. Generally, these surface areas are of essentially equal size. Once bullet 14 has exited from the interior of the silencer, the combustion gases discharge to normal pressure along the trajectory of the bullet, through guide cone 20 and deflector cone 21. Due to the small excess pressure, the discharge pipe can essentially empty before the following shot. One of the tasks of the guide cone is to separate the gas flows to travel in different directions. Figures 3a and 4a show the components of a silencer according to the invention separated from one another, in the assembly position. Usually, collar 18 and seal component 23 are first attached to discharge pipe 15. Collar 18 and seal component 23 are manufactured to suit a specific gun. The other components are essentially able to be used generally. Collar 18 has an internal thread 24 corresponding to thread 25 on barrel 13, for attachment to barrel 13. Collar 18 has also several drilled holes 26 to permit a flow from end piece 19 to discharge pipe 15. Collar 18 is shown in Figures 3b and 4d in a front view. In the embodiment, there are eight drilled holes 26 in collar 18. Generally, the surface area of the drilled holes is 20 - 50 %, preferably 30 - 40 % of the cross-sectional surface area of collar 18. In addition, the ends of both collar 18 and barrel 13 have precisely fitting machined areas 27 and 27', which ensures that the attachment of the silencer is correctly aligned. Corre- spondingly, a precise fit is arranged between seal component 23 and barrel 13. Practically no pressure passes through the attachment while at the same time a small amount of gas seals the seal component to the barrel. In addition, the attachment prevents the silencer from moving, unlike flexible seals. Both attachments are preferably so-called push fits, in which there are small clearances and tolerances. Despite its tightness, the attachment can be dismantled without tools. Collar 18 and seal component 23 are also attached to discharge pipe 15 by means of threads . Guide cone 20 and deflector cone 21 are fitted inside end piece 19 without actual securing members. Both cone components 20 and 21 rest on shoulder 28 of end piece 19. In addition, guide cone 20 fits into conical hole 29 machined in collar 18. In Figure 4c, the longitudinal projection of guide cone 20 has been turned through 45°, so that it lies inside deflector cone 21. Figure 4b also shows end face 21" of deflector cone 21, which, at a high pressure, provides a powerful counterforce to the recoil. Correspondingly, there are end faces in the prongs 21' of deflector cone 21, which have the same effect. The shoulder 28 of the end piece also forms a single end face. Mainly the combined action of the holes and various end faces of the cones, and especially of the guide cone, creates a phased and controlled counterforce to the recoil. A significant counter- force arises, when the high-pressure combustion gases collide with the end faces and turn rapidly through 180°. In addition, the phased nature of the collisions and changes in direction of travel distributes the stresses evenly over the various parts of the silencer, so that the silencer will withstand even powerful charges. Generally, the end-face surface area of deflector cone 21 is 2 - 5 times the square of the caliber of the gun. The diameters of the inner holes of cone components 20 and 21 and collar 18 are essentially larger that the diameter of bullet 14, so that they do not affect the trajectory of the bullet. End piece 19 is machined in the same way as the other components in front of the mouth of the barrel. In addition, the end piece is drilled and all its internal shapes are turned for the same fitting. Thus, the accuracy of the aim of the gun is retained, despite the opening of the silencer. After the fitting of cone components 20 and 21, end piece 19 screwed onto collar 18, when the silencer is ready for use. In practice, in order to create a sufficiently large expansion chamber, the length of the discharge pipe is 250 - 650 mm, preferably 350 - 550 mm. Despite the length of the discharge pipe, the silencer scarcely increases the length of the gun. There is also no increase in the front-heaviness of the gun. Generally, the discharge pipe preferably has a circular cross- section and an external diameter that is 6 - 20 %, preferably 8 - 14 % of the length of the discharge pipe. In practice, the external diameter of discharge pipe 15 is 35 - 65 mm, preferably 40 - 60 mm. By means of its phased operation, the silencer will withstand the stresses caused by even powerful charges. This reduces the impact stress, especially on the front piece. In addition, the silencer is simple and has no places in which impurities will tend to collect. On the other hand, the flow channels in the silencer are so large that there is no danger of blockages. Thus, the servicing interval of the silencer becomes about 1000 shots, or twice a year. The silencer is also easy to dismantle and clean of combustion debris. After cleaning, the gun is ready for use, without realignment. The entire silencer, or at least the discharge pipe, is manufactured from aluminium metal. This means that the total weight of the silencer is about 600 grammes. The aluminium metal is preferably an AlSil alloy, which is light, but durable and easily machined and anodized. Preferably all the components of the silencer are anodized. This makes it easier to clean the components and particularly the cone components, while anodizing makes the end piece and outside of the discharge pipe highly resistant to wear. If necessary, it is easy to increase the effect of the si- lencer. A second end piece, in which there are also guide members, can be added as an extension to the end piece, with suitable alterations. However, the additional piece has no flow connection to the discharge pipe. The additional piece is thus intended to attenuate the exhaust pressure discharging from the silencer. Furthermore, the effect and especially the pressure resistance of the silencer can be improved simply. Figure 5a shows another embodiment of the invention, in which an additional discharge pipe 15' is arranged on top of jacket 17. Together with jacket 17, additional discharge pipe 15' delimits an additional expansion chamber 16'. In addition, openings 30 are arranged in end piece 19, to guide the combustion gases to the aforesaid additional expansion chamber 16', from which there are other openings 30' to expansion chamber 16. Thus, the combustion gases are given a greater volume. In practice, openings 30 and 30' are drilled holes, of which there are both eight in the example. In Figures 5a and 5b, the drilled holes are shown shaded. The silencer according to Figure 5a operates during the initial stage of the shot in the manner described above. In the initial stage, the combustion gases turn, in this case, through the extended guide cone 20, to discharge pipe 15. There are several rows of holes 22 in guide cone 20, to lead the combustion gases in a controlled manner and in stages to expansion chamber 16. As bullet 14 continues to move forward, a new path is also opened, through the openings 30 machined in the extended end piece 19, and from there to addition expansion chamber 16' and then to expansion chamber 16 (Figure 5a) . At the same time, the combustion gases progressing in discharge pipe 15 suck the discharge gases with them through the openings 30' of addi- tional discharge pipe 15'. Figure 5b shows end piece 19 and additional discharge pipe 15' and locking piece 19', which are fitted onto it. The assembly of the silencer takes place in the manner described above. Finally, additional discharge pipe 15' is pushed onto end piece 19 and secured with locking piece 19'. For this purpose, there is a first thread 31 in the end of end piece 19, the corresponding thread 31' to which is in locking piece 19'. Additional discharge pipe 15' is sealed with a rubber seal 32. This, however, has no effect on the accuracy of aim of the gun, because additional discharge pipe 15' is attached to end piece 19. Additional discharge pipe 15' is, for example, 200 mm long and has a diameter of 56 mm. One typical application is a .308 caliber game-target event competition gun, which uses a telescopic sight with high mounting bases. The properties of the silencer are emphasized in connection with such a gun. The attenuation of the recoil improves the accuracy of aim and reduces the strain on the competitor, especially when firing series. The attenuation of the sound is especially advantageous to spectators. In addition, the total weight of the gun remains reasonable and, despite dismantling and cleaning, the accuracy of aim of the gun is retained.

Claims: CLAIMS 1. A gun silencer, which comprises an essentially cylindrical jacket (17), and which is intended to be detachably attached especially to the end of the barrel (13) of a high- pressure gun (11) , such as a rifle, and additionally partly around the barrel (13) parallel to it, and into the expansion chamber (16) delimited by which jacket (17) and the barrel (13), are the combustion gases, which are released from the mouth of the barrel (13) after the bullet (14) in connection with a shot, arranged to discharge, in order to attenuate the sound of the shot, the silencer (10) further including a deflector cone (21) being arranged in front of the barrel (13) to deflect the combustion gases from the trajectory of the bullet (14) into the expansion chamber (16), which is restricted, at least in front, by an end piece that reflects the combustion gases, characterized in that most of the expansion chamber (16) is arranged backwards from the mouth of the barrel (13), and that the silencer (10) includes a guide cone (20), which is set around the mouth of the barrel (13) and expands forwards from it and extends coaxially around the deflector cone (21), and in which there are holes (22), to guide the combustion gases partly outside the guide cone (20) . 2. A silencer according to Claim 1, characterized in that the guide cone (20) , the deflector cone (21) , and the front end of the jacket (17) are arranged to form a counter- force to the recoil, by arranging a substantial end face (21") to the combustion gases discharging from the mouth of the barrel (13) and turning the direction of travel of the combustion gases rapidly through 180°. 3. A silencer according to Claim 1 or 2, characterized in that at least 70 %, preferably 75 - 85 %, of the expansion chamber (16) of the silencer (10) is behind the mouth of the barrel (13) . 4. A silencer according to one of Claims 1 - 3, characterized in that the silencer (10) is arranged to be attached to the end of the barrel (13) by means of a collar (18), around which both the discharge pipe (15) as part of the jacket (17) and the end piece (19) containing the guide cone (20) and the deflector cone (21) are detachably attached. 5. A silencer according to Claim 4, characterized in that openings (26) parallel to the barrel (13) are arranged in the collar (18), to lead the combustion gases from the end piece (19) to the discharge pipe (15), the surface area of the openings (26) being 20 - 50 %, preferably 30 - 40 % of the cross-sectional surface area of the collar (18). 6. A silencer according to Claim 4 or 5, characterized in that the length of the discharge pipe (15) is 250 - 650 mm, preferably 350 - 550 mm. 7. A silencer according to one of Claims 4 - 6, characterized in that the discharge pipe (15) preferably has a circular cross-section and an external diameter that is 6 - 20 %, preferably 8 - 14 % of its own length. 8. A silencer according to one of Claims 4 - 7, characterized in that the external diameter of the discharge pipe (15) is 35 - 65 mm, preferably 40 - 60 mm. 9. A silencer according to one of Claims 4 - 8, characterized in that the entire silencer (10), or at least the discharge pipe (15) , is made from aluminium metal, which is preferably an AlSil alloy. 10. A silencer according one Claims 1 - 9, characterized in that an additional discharge pipe (15') is fitted on top of the jacket (17), and is arranged with the jacket (17) to delimit an additional expansion chamber (16'). 11. A silencer according to Claim 10, characterized in that primary openings (30) are arranged in the end piece (19) that is part of the jacket (17) to guide the combustion gases into the aforesaid additional expansion chamber (16'), from which there are secondary openings (30') into the expansion chamber (16) .

Inventors: SILVENNOINEN MARTTI, SILVENNOINEN, MARTTI
Applicants: SILVENNOINEN MARTTI, SILVENNOINEN, MARTTI
Application year: 2000
Main classification: F41A21
IPC codes: F41A21