EP0093211B1

EP0093211B1 - Adjustable sound suppressor for weapon

Info

Publication number: EP0093211B1
Application number: EP82302242A
Authority: EP
Inventors: Charles Albert Finn
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-04-30
Filing date: 1982-04-30
Publication date: 1987-12-16
Also published as: EP0093211A1; ATE31453T1; DE3277848D1

Abstract

A sleeve 30 is slidably longitudinally of a can 14, on a weapon 12, containing sound suppressing means 10, between a first position retracted onto the can and a second position extending forwardly from the can with only adjacent ends lapping, to enhance sound suppressing action when the sleeve 30 is moved to the second extended position. A longitudinally extending slot 80 in the sleeve, with laterally extending notches 82, and a stop 84 disposed in the slot 80 to limit movement of the sleeve 30 on the can 14. A knob with lock means to secure the stop in a selected notch of the slot.

Description

This invention relates to a sound suppressor for a firearm and particularly to means for increasing sound suppression in a sound suppressor when desired by increasing its length and to reduce the length of the suppressor on the weapon when desired by retraction.
Sound suppressors for use with weaponry are well known and have taken the form of a single sound suppressor can attachable to the muzzle of a rifle barrel, for example. Efficient sound reduction is dependent to a large extent on baffles within the suppressor can. However, such suppressors are not able to cope successfully with the precursor wave, that is, the compressed air volume in front of a projectile nor with the expansion of gases within the can thereby reducing the efficiency of the sound suppression.
These problems have to some extent been reduced by increasing the lateral dimension of the suppressor can, relative to the projectile path. However, much known sound suppressors are bulky and difficult to handle. Further attempts to overcome the above mentioned problems and the unacceptable increase in size of the suppressor can, has substantially been overcome by providing an additional expansion chamber on the exit end of the sound suppressor can.
A telescopic suppressor is disclosed in U.S. Patent 4,203,347 positioned at the rear end and not muzzle end of the barrel of a rocket launcher and is closed for transportation and extended when mounted on the rocket launcher. However, once extended the suppressor remains extended and is discarded after a single round. The suppressor has only two positions and is not movable to intermediate positions between the extremities of movement. Furthermore, the length of the individual sections of the telescopic sections is short and an insufficient noise reduction is achieved because the shock wave resulting from the emission of the rear plug of the launcher passes quickly through the extended suppressor. Moreover the disclosed suppressor is not an attachment to the existing suppressor.
DE-C-214226 discloses a sound suppressor for attachment to firearms of the type defined in preamble of claim 1 and is adjustable laterally by twisting superimposed cylindrical tubes to open or close slits in the side walls of the tubes. However, no significant longitudinal movement between the tubes is considered possible. Furthermore, grasping the casing during a firing sequence to adjust the slits would result in a burned hand since hot gases are emitted from the slits. This latter emission of gases through the slits reduces the efficiency of the sound suppressor.
The present invention seeks to overcome the above problems and to obtain considerable sound reduction by providing a telescopic sound suppressor in which a secondary expansion chamber receives and dampens sound caused by the precursory wave in front of the projectile as defined by claim 1. The secondary chamber is adjustable by mechanical interlocking of the telescopic sections to vary the size of the expansion chamber according to operating conditions. The can defining the secondary chamber is mountable on an existing sound suppressor and allows the projectile, in each operative condition, to exit prior to the precursory wave thus considerably reducing sound emission.
Whilst seeking to achieve these ends, particularly to maximize sound suppression it is also advantageous to minimize the bulk or length of the suppressor for easier handling.
The structure is of a simple, safe and reliable action, and seeks to devise means for operation even in the dark, to provide means to lock the structure in a selected position, and to devise a low cost device and one requiring minimum maintenance.
The invention will now be described by way of example with reference to the accompanying drawings, in which

Figure 1 is a longitudinal view, partly in section of a specific embodiment of my new adjustable sound suppressor for a weapon;
Figure 2 is another longitudinal view, partly in section;
Figure 3 is an exploded perspective view;
Figure 4 is a view, partly in section, taken on line 4-4 of Figure 1; and
Figure 5 is a view, partly in section, taken on line 5-5 of Figure 1.

The applicant's concepts of an adjustable sound suppressor can be summarized in part as follows:

1. Provide a telescoping sleeve on a sound suppressor can that may be extended to provide an expansion chamber forward of the can. The forward chamber can accommodate the precursor wave, i.e., the compressed air volume in front of a projectile. Depending on the speed of the projectile relative to the speed of sound, this can be a shock wave. In other words, the compressed air may expand or displace to the side thereby permitting the projectile to exit before the precursor wave, instead of the precursor wave having to exit from the sound suppressor before the projectile. By exiting after the projectile, the wave or volume of compressed air may exit over a longer duration of time and therefore exit at a considerably lower sound level.
2. When the sleeve is extended, a large secondary expansion chamber is provided in the sleeve forward of the end of the can. The extra chamber allows for further expansion of gases, in addition to the expansion of gases that occur in the can. In this way, gases not only expand more before exiting from the suppressor but also the gases escape over a longer duration of time and produce a lower sound level.
3. The sleeve concept, by its collapsible nature and its efficiency, makes it possible to reduce the overall size of a sound suppressor, i.e., for a given amount of sound suppression, the collapsed suppressor will have less length or volume than the normal non-collapsible suppressor.
4. The sleeve concept lends itself to basically every known suppressor type.
5. Preliminary tests of a prototype have shown 68% greater sound suppression by adding the sleeve to the can of an existing type of sound suppressor.

It should be understood that the preceding discussion of the operation of compressed air, etc., involved in the addition of an extended sleeve to a sound suppressor, as shown and described, is theoretical. The important thing is the results obtained, which are not theoretical, whether or not the technical explanation of operation is correct or complete. As far as is known, the 68% improvement is representative of what can be achieved with my invention, whether or not my description of why or how it works is completely accurate technically or scientifically. When sleeves of various lengths, etc., are added to other suppressors, possibly greater or less sound reductions will be achieved, but I have demonstrated that results can be quite significant.
In the drawings a suppressor 10 is added to weapon 12 symbolized by its barrel. A sound suppressor can 14 has sound suppressing means 16 indicated by a general block. The sound suppression means 16 can be of any conventional or suitable type which will commonly involve baffles.
Can 14 has a bored projectile entrance plug 20 and a bored projectile exit plug 22 shown as threadedly secured in place by threads 24 on the interior of the can and by threads 26 on the exterior of the plugs. The flange 28 on exit plug 22 should be small enough to fit within sleeve 30, whereas the flange 32 on entrance plug 24 may be of sufficient diameter to lap the ends of sleeve 30 when the sleeve is retracted although other stop means for the retraction of sleeve 30 are provided.
Sleeve 30 is slidably mounted on can 14 and is movable between a first fully retracted position and a second fully extended position with only the adjacent ends of sleeve and can lapping. It will be observed that when sleeve 30 is fully extended it forms another secondary sound suppressing expansion chamber 34 in addition to the chamber of can 14. The chamber 34 is closed by a bored projectile exit plug 40 secured in place by threads 42 on plug 40 and by threads 44 on the inside of sleeve 30. Plug 40 has a flange 46.
The sound suppressing action of sleeve chamber 34 presumably has something to do with providing expansion room for gas exiting with or ahead of a projectile. As above indicated, the correct analysis of the reason for its effectiveness is not necessarily known but its effectiveness has been measured at 68% increase in sound suppression in one model.
The sound suppressor 10 is suitably attached to the barrel 12 of a weapon. In the attaching structure shown, it is part of can entrance plug 20 and includes the threaded bore 50 of plug 20 which engages with threads 52 on barrel 12. To secure suppressor 10 from becoming unthreaded from barrel 12, the rear portion or boss 54 of plug 20 is diametrically split at 56. Boss 54 has external threads 58 and a split nut 60 with internal threads 62 engages threads 58. Set screws 64 extend through openings 66 and are threaded into openings 68 on opposite sides of the split 70 of nut 60, whereby screws 64 can be tightened to compress boss 54 on barrel 12 to lock plug 20 from becoming unthreaded from the barrel. Surface 72 inside boss 54 is not threaded but may be scored in the process of making threads 50 whereby surface 72 will have additional functional gripping on barrel 12.
Sleeve 30 has a longitudinal slot 80 and a series of notches 82 extending laterally therefrom. A stop 84 attached to can 14 extends into slot 80. When stop 84 is at one end of slot 80, sleeve 30 is fully extended, and when stop 84 is at the other end of slot 80, sleeve is fully retracted. Notches 82 represent other selected positions which, along with the extreme ends of slot 80, may be sensed tactilely without looking or even in the dark, so that positioning of sleeve 30 on can 14 does not depend on light or on having time to look, but instead can be done rapidly by sense of feeling as the user gains experience with use of suppressor 10.
Stop 84 is a bolt screwed into can 14 and having a knurled head 86 and a locking washer 88. Thus, stop 84 can be secured in adjusted position in slot 80 or in one of the notches 82 by manually tightening the bolt by means of knurled head 86.

Claims

1. A sound suppressor for firearms in which the sound suppressor (10) comprises a cylindrical can (14) having a projectile entrance plug (20) at one end which is attachable to the muzzle (12) of a firearm, internal sound suppressing means (16) and an opposite end having an end plug (22) with a projectile exit opening, characterised by a secondary cylindrical sleeve (30) having an internal diameter dimensioned to slidably fit over the sound suppressor can (14), said secondary cylindrical sleeve having an end plug (46) with a bore therein to allow the exiting of a projectile therethrough, said end plug (46) and secondary cylindrical sleeve (30) defining a secondary suppressor chamber of variable volume depending upon the extent of overlap of the secondary cylindrical sleeve over the cylindrical wall of the standard sound suppressor, said secondary cylindrical sleeve including securing means (20) having multiple securing positions (82) to allow securing of the second cylindrical sleeve at any of a number of extended positions, said securing means (60) including a manual control operable by the user of the firearm by tactilely selecting and locking the secondary cylindrical sleeve at the desired position while the firearm is in a firing position.

2. A sound suppressor as claimed in Claim 1, characterised in that said securing means includes a slot (80) in said sleeve extending longitudinally of said suppressor (10) in a stop (84) extending from said can into said slot (80) thereby limiting movement of said sleeve (30) relative to said can (14).

3. A sound suppressor as claimed in Claim 2, characterised in that the stop (84) is a threaded body with a manually operable knob (86) with lock means (88) whereby said stop can be tightened to lock said sleeve in position on said can.

4. A sound suppressor as claimed in Claim 3, characterised in that the securing positions (82) are provided by a plurality of notches (82) extending laterally from said slot (80) in which said stop can be selectively positioned to index extension of said sleeve relative to said can (14) and for locking of said stop in a selected position.

5. A sound suppressor as claimed in any preceding claim, characterised in that said exit end plug (28) of said can (14) has a flange fitting the interior of said sleeve (30) and in which said entrance end wall on said can (14) is a bored entrance end plug (20) having an external flange (32) against which said sleeve abuts in said first position of said sleeve as an inner stop, and in which said plugs are threadably secured in place in said can and sleeve.