GB2192977A - Silencer - Google Patents

Abstract

A silencer for firearms or i.c. engine exhausts comprises a hollow body having an inlet formation (10) with an entry sound absorption chamber (13) surrounding a through passage (12), a tubular resonance absorption chamber (21) downstream thereof having a spiral interior ridge (22) or other disconformities eg. a plurality of small cup-shaped formations, and an outlet formation (30), preferably including an annular flame suppression chamber (32) surrounding a through passage (31) and provided with a volute coil (34) of flat metal strip or other labyrinth formation, and a pair of open-ended branch passages (36) at right angles to through passage (31). <IMAGE>

Description

SPECIFICATION Silencer This invention relates to silencers particularly for use with firearms though the invention may have application to the silencing of high velocity propulsion or discharge of gases through or from conduits or apertures other than firearms e.g. in connection with internal combustion engine exhausts.

The object of the invention is to provide a silencer which is of simple and durable construction, which does not substantially affect the performance or output of the device to which it is operatively fitted, and which is particularly effective in use.

According to the invention there is provided a silencer including a hollow elongate body having an inlet formation adapted for mounting on or connection to a firearm barrel or other conduit or aperture through or from which high velocity gas flows are propelled or discharged in use an outlet formation apertured for passage of gas flow and any projectile or other body carried thereby from the silencer, and at least one resonance absorption chamber of substantially greater average cross section area than that of the passages through the inlet and outlet formations, said chamber having interior turbulence inducing ridges, grooves or other disconformities on or in its peripheral wall structure.

While the thickness of said wall structure may be substantially uniform along its length as by its exterior surface being provided with complementary grooves, ridges or other disconformities, e.g. by the wall structure itself being corrugated, it is preferred that the exterior surface is substantially uniform and smooth, said disconformities being provided by variations in wall thickness.

Said disconformities may consist of or in dude one or more spiral ridges and or grooves around the interior of a cylindrical wall structure.

Additionally to said resonance absorption chamber, the inlet formation may include an entry sound absorption chamber opening laterally of a main passage through said formation and preferably containing or being filled with a body or bodies of a sound absorbing fibrous, porous, cellular, particulate or similar material. Subsidiary passages may be provided opening from the latter chamber into the upstream end of the resonance absorption chamber in parallel with the main passage.

The silencer may further include, either in combination with said entry chamber or otherwise, one or more suppression chambers opening laterally of a main through passage of said formation or formations, preferably of the outlet formation and containing one or more labyrinth formations, typicaly volute coils of flat strip metal or other material into the interstices of which passes a laterally expanding portion of the flame or other gas flow in use.

The outlet formation may further include one or more laterally opening apertures branching from the main through passage for lateral discharge or dispersal of a proportion of the gases and/or the sound emanating from their discharge as a projectile propelled thereby exits from the main passage.

One example of the invention is now more particularly described with reference to the accompanying drawings wherein: Figure 1 is a partly sectioned perspective view of a silencer for fitting to the barrel of a firearm and Figure 2 is a longitudinal section of the silencer.

The silencer is built up from generally cylindrical tubular components to form a hollow body.

Said components include inlet formation 10 including an end socket 11 to be operatively secured on the end of the firearm barrel eg. by means of a clamp screw.

A distal end part of formation 10 defines a central through passage 12 of at least the diameter of the firearm bore and in coaxial alignment therewith in use and an annular entry sound absorption chamber 13 in surrounding relationship to passage 12 and connected therewith by a plurality of ports 14 opening laterally of said passage at equi-angular positions, e.g. four in number.

Chamber 13 contains a filling of a heat-resistant sound absorbing material, preferably having a degree of resilience. Various said materials may be used, for example a fibrous material, and/or a particulate or foamed cellular elastomeric material.

Small subsidiary passages 16 open from chamber 13 in the downstream direction parallel to central passage 12.

Immediately downstream of formation 10 is an increased diameter tubular section 20 having a uniform external diameter equivalent to that of formation 10 so that the silencer has a generally smooth exterior and defining a resonance absorbtion chamber 21 of substantial axial length e.g. just over twice the overall diameter of section 20.

The interior wall structure of chamber 21 includes disconformities along its length in this example constituted by the axially spaced turns or coils of a spiral ridge 22 forming part of or mounted on the interior wall structure of the chamber. In this example the ridge is square in cross section and projects from the general envelope of the interior wall by about one tenth or more of the chamber diameter. It is to be understood that other forms of ridges or grooving could be used to provide said disconformities.

The. purpose of the disconformities is to introduce a degree of turbulence into the gas flow along chamber 20 modifying the propul sion of the gases therethrough and, in particular, their boundary layer adjacent to the chamber wall so as to reduce the sound level and resonance by creating vortices and preventing or interfering with the formation of standing waves within the chamber. In the preferred form as a ridge or ridges within the chamber the disconformities may also provide a degree of stiffening or enhanced rigidity to the chamber walls reducing the resonance of the chamber structure itself and its ability to transmit sound vibrations to the chamber exterior.

The distal end of tubular section 20 mounts an outlet formation 30 defining an axial main through passage 31 aligned with and of substantially equivalent diameter to through passage 12.

The upstream end part of formation 30 defines an annular flame suppression chamber 32 in surrounding relationship to part of passage 31 and in communication therewith by way of lateral ports 33 similar to the arrangements of chamber 13 in formation 10.

Chamber 32 contains a labyrinth formation in the form of a volute coil 34 of flat metal strip similar in shape to a clock spring disposed coaxially to passage 31. The expanding gases and flames passing from chamber 21 along passage 31 can expand laterally into and be dispersed, absorbed and cooled by the interstices between the turns of coil 34 within chamber 32.

In an alternative construction one or more of the coiled or other labyrinth formations is mounted in or possibly on the exterior of outlet formation 30 in coaxial relationship to lateral ports 33 to act in the same way.

The downstream distal end portion of formation 30 includes a pair of open ended branch passages 36 extending at right angles to through passage 31 adjacent the exit open ing of the latter from the silencer. These passages permit further dispersal of the propellent gases and sound laterally immediately before the projectile leaves the silencer. This further reduces the level of sound projected forwardly from the firearm on discharge.

While use of all three chambers 13, 20 and 32 and their associated formations is preferred in combination, conveniently together with the provision of the branch passages 36, it is to be understood that either or both the entry and flame suppression chambers 13 and 32 may be dispensed with in some forms of the invention, as may the branch passages 36, e.g. a form of silencer is contemplated in which only the resonance absorption chamber 21 is provided with its ridging or other internal discomformities.

It is contemplated that the spiral ridge 22 or other interior disconformities of chamber 21 may be provided in the form of a shaped insert positioned within section 20 on assembiy.

The disconformities may comprise a plurality of small cup shaped formations.

Further insulation and sound damping may be provided using materials such as a urethane foam based sheet material coated with a lead film eg as supplied by Bestobell Ltd; and/or a heat-resistant silicone elastomer as sold under the trade mark or trade name "Silastomer"; and/or a tumescent foam material which will expand and cure either as part of the assembly process or as a result of early use of the silencer both to locate the components and secure them against vibration or rattling and to dampen or otherwise modify the sound. Such materials might be used as an adjunct to the metal volute coil 34 in chamber 32 to position and secure it. Such tumescent materials include fluorocarbon based plastics material. One suchproduct is the tumescent foam supplied by Woodville Polymer Engineering Ltd.

Claims (13)

1.. A silencer including a hollow elongate body having an inlet formation adapted for mounting on or connection to a firearm barrel or other conduit or aperture through or from which high velocity gas flows are propelled or discharged in use, an outlet formation apertured for passage of gas flow and any projectile or other body carried thereby from the silencer, and at least one resonance absorption chamber of substantially greater average cross section area than that of the passages through the inlet and outlet formations, said chamber having interior tubulence-inducing ridges, grooves or other disconformities on or in its peripheral wall structure.

2. A silencer as in Claim 1 wherein the thickness of said wall structure is substantially uniform along its length as by its exterior surface being provided with complementary grooves, ridges or other disconformities.

3. A silencer as in Claim 2 wherein the wall structure itself is corrugated.

4. A silencer as in Claim 1 wherein the exterior surface of the wall structure is substantially uniform and smooth, said disconformities being provided by variations in wall thickness.

5. A silencer as in Claim 4 wherein the disconformities consist of or include one or more spiral ridges and/or grooves around the interior of a cylindrical wall structure.

6. A silencer as in any preceding claim wherein additionally to said resonance absorption chamber, the inlet formation includes an entry sound absorption chamber opening laterally of a main passage through said formation.

7. A silencer as in Claim 6 wherein the entry sound absorption chamber contains or is filled with a body or bodies of a sound absorbing fibrous or similar material.

8. A silencer as in Claim 6 or 7 including opening from said entry chamber into the up stream end of the resonance absorption chamber in parallel with the main passage.

9. A silencer as in any preceding claim including one or more suppression chambers opening laterally of a main through passage of said formation or formations and containing one or more labyrinth formations into the interstices of which passes a laterally expanding portion of the flame or other gas flow in use.

10. A silencer as in Claim 9 wherein said suppression chamber or chambers open laterally of a main through passage of the outlet formation.

11. A silencer as in Claim 9 or 10 wherein the labyrinth formation or formations include coils of flat strip material.

12. A silencer as in any preceding claim wherein the outlet formation includes one or more laterally opening apertures branching from the main through passage for lateral discharge or dispersal of a proportion of the gases and/or the sound emanating from their discharge as a projectile propelled thereby exits from the main passage.

13. A silencer substantially as hereinbefore described with reference to and as shown in the accompanying drawings.