U.S. patent application number 14/832532 was filed with the patent office on 2016-02-25 for gun sound moderator.
The applicant listed for this patent is William Westlake. Invention is credited to William Westlake.
Application Number | 20160054086 14/832532 |
Document ID | / |
Family ID | 51726895 |
Filed Date | 2016-02-25 |
United States Patent
Application |
20160054086 |
Kind Code |
A1 |
Westlake; William |
February 25, 2016 |
GUN SOUND MODERATOR
Abstract
A gun sound moderator 30 has an external moderator cylinder wall
50 inside which is a series of stages 54 each having a baffle 32
formed with a concentric hole 46 which is concentric with the
cylinder wall 50 and a deflector 38, gas passing through the
concentric hole being deflected by the deflector 38 so as to move
with a radial component towards an end to move with a circulatory
motion along/around inside the moderator cylinder wall 30 so as to
achieve improved heat transfer from the gas through the moderator
cylinder wall and into the ambient atmosphere outside the gun sound
moderator so as to achieve cooling of the gas so as to reduce its
volume and controlled gas release to atmosphere, so as to achieve a
relatively quiet report/noise when a projectile 20 is fired through
the gun sound moderator.
Inventors: |
Westlake; William;
(Cambridge, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Westlake; William |
Cambridge |
|
GB |
|
|
Family ID: |
51726895 |
Appl. No.: |
14/832532 |
Filed: |
August 21, 2015 |
Current U.S.
Class: |
89/14.4 ;
181/223 |
Current CPC
Class: |
F41A 21/30 20130101 |
International
Class: |
F41A 21/30 20060101
F41A021/30 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2014 |
GB |
1414871.2 |
Claims
1. A gun sound moderator which is adapted to mount at a gun barrel
muzzle, the moderator having a body, the body having a longitudinal
axis and having a moderator cylinder wall having an internal
surface within which are a plurality of moderating stages, each
stage having (A) a baffle formed across and inside the cylinder
wall and having a concentric hole which is concentric with the
moderator cylinder wall; and (B) a deflector adapted to deflect gas
flow from the concentric hole to move with a radial component so as
to impact the internal surface of the moderator cylinder wall and
be guided for circulation around the same.
2. A gun sound moderator as claimed in claim 1 in which the
deflectors in different stages are positioned rotated apart
relative to one another at each stage.
3. A gun sound moderator as claimed in claim 1 in which each stage
has more than one said deflector.
4. A gun sound moderator as claimed in claim 2 in which each stage
has more than one said deflector.
5. A gun sound moderator as claimed in claim 3 in which two said
deflectors at each stage are positioned angularly rotated
180.degree. relative to one another about the longitudinal axis of
the body.
6. A gun sound moderator as claimed in claim 4 in which two said
deflectors at each stage are positioned angularly rotated
180.degree. relative to one another about the longitudinal axis of
the body.
7. A gun sound moderator as claimed in claim 3 in which each
deflector, when viewed cutaway in a direction from a side of the
body, looks straight and angled at approximately 45.degree. to the
longitudinal axis of the body.
8. A gun sound moderator as claimed in claim 2 in which each
deflector is curved with a radius in a section viewed across the
longitudinal axis of the body.
9. A gun sound moderator as claimed in claim 5 in which each
deflector is curved with a radius in a section viewed across the
longitudinal axis of the body.
10. A gun sound moderator which is adapted to mount at a gun barrel
muzzle, the moderator having a body, the body having a longitudinal
axis and having a moderator external wall having an internal
surface within which is at least one moderating stage, each stage
having (A) a baffle formed across and inside the external wall and
having a gas passage formed for the flow of gas therepast; and (B)
a deflector adapted to deflect gas flow from the gas passage to
move so as to flow towards the inside of the moderator external
wall and be guided for circulation around the same.
11. A gun sound moderator as claimed in claim 10 in which the
moderator external wall is circularly cylindrical.
12. A gun sound moderator as claimed in claim 10 which includes a
plurality of said stages.
13. A gun sound moderator as claimed in claim 10 in which the gas
passage comprises a hole formed through the baffle and concentric
with a centre longitudinal axis of the body of the gun sound
moderator.
14. A gun sound moderator as claimed in claim 13 in which each
deflector includes a first wall surface which is curved so as to
deflect gas travelling from the hole towards the external wall, the
first wall surface preferably being an at least part circularly
cylindrical first wall surface and oriented with a longitudinal
direction thereof substantially perpendicular to the central
longitudinal axis of the body.
15. A gun sound moderator as claimed in claim 13 in which each
deflector includes a second wall surface which is planar or
substantially planar and which is oriented substantially parallel
to the longitudinal direction of the at least part circularly
cylindrical first wall surface.
16. A gun sound moderator as claimed in claim 13 in which each
deflector includes a second wall surface which is planar or
substantially planar and which is oriented substantially parallel
to the longitudinal axis of the body.
17. A gun sound moderator as claimed in claim 14 in which each
deflector includes a third wall surface, the third wall surface
together with the external wall forming a passage therebetween for
the flow of gas therethrough with a circulatory or rotational
motion around inside and guided by the external wall.
18. A gun sound moderator as claimed in claim 17 in which the third
wall surface has a curved profile and substantially comprises part
of a surface of revolution whose imaginary axis of rotation is on a
convex side of the curved profile.
19. A gun sound moderator as claimed in claim 18 in which the
curved profile is substantially semi-circular.
20. A gun sound moderator as claimed in claim 15 in which each
deflector includes a third wall surface, the third wall together
with the external wall forming a passage therebetween for the flow
of gas therethrough with a circulatory or rotational motion around
inside and guided by the external wall.
21. A gun sound moderator as claimed in claim 20 in which the third
wall has a curved profile and substantially comprises part of a
surface of revolution whose imaginary axis of rotation is on a
convex side of the curved profile.
22. A gun sound moderator as claimed in claim 21 in which the
curved profile is substantially semi-circular.
23. A gun sound moderator as claimed in claim 10 in which each
deflector is configured to deflect gas to adopt an at least partly
toroidal motion within the body of the moderator.
24. A gun sound moderator as claimed in claim 1 which has a
toroidal passage formed within the body for toroidal gas flow
therethrough, the passage including at least one flow guide
extending along within the toroidal passage.
25. A gun sound moderator as claimed in claim 10 which has a
toroidal passage formed within the body for toroidal gas flow
therethrough, the passage including at least one flow guide
extending along within the toroidal passage.
26. A gun sound moderator as claimed in claim 24 in which the at
least one flow guide comprises a fin or vane; optionally in which
the fin or vane is generally planar; optionally in which at least
one said fin or vane extends in a direction generally perpendicular
to or perpendicular to the longitudinal axis of the body.
27. A gun sound moderator as claimed in claim 25 in which the at
least one flow guide comprises a fin or vane; optionally in which
the fin or vane is generally planar; optionally in which at least
one said fin or vane extends in a direction generally perpendicular
to or perpendicular to the longitudinal axis of the body.
28. A gun having a gun barrel with a muzzle and a gun sound
moderator as claimed in claim 1 mounted at the muzzle.
29. A gun having a gun barrel with a muzzle and a gun sound
moderator as claimed in claim 10 mounted at the muzzle.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to gun sound moderators,
including those for use on guns and firearms, e.g. small arms.
BACKGROUND OF THE INVENTION
[0002] Gun sound moderators are used to make the report from the
end of gun barrel's muzzle quieter so that the operators of guns
and the surroundings have limited exposure to loud noise. Ideally,
gun sound moderators should combine quietening of the report of the
gun together with small size and lightness. Small size is preferred
to ensure that gun sound moderators do not obscure the target
through the sighting system of the gun and lightness is preferred
so as to not overly impact the balance and handling of the gun to
which the gun sound moderator is attached. Since the gun sound
moderator is located at the end of the gun, this can have a
significant impact due to the weight of the gun sound moderator
being at a distance from the place at which the gun is held and
high weight can adversely impact the package weight of the gun plus
the gun sound moderator.
[0003] Gun sound moderators are typically cylindrical with a
concentric hole through them, the moderator being attached, by some
means, to the end of the gun barrel such that a concentric hole
through the centre of the gun sound moderator is in alignment with
the bore of the gun barrel such that the projectile leaving the gun
barrel can pass directly through the gun sound moderator, the
projectile leaving the muzzle of the gun barrel and passing through
the concentric hole of the gun sound moderator. In doing so, the
report (noise) of the gun is reduced. Gun sound moderators
typically use a series of baffles so as to reduce the report/noise
of the gun when fired, the baffles reducing the report by
interfering with the exit of the high-pressure gas that has been
generated to push the projectile from the barrel.
[0004] To achieve a level of report/noise reducing properties,
however, known gun sound moderators tend to be relatively large.
Thus, it is difficult to produce a small, light gun sound moderator
that is also quiet.
SUMMARY OF THE INVENTION
[0005] The present invention aims to alleviate at least to a
certain extent the problems of the prior art.
[0006] According to one aspect hereof there is provided a gun sound
moderator which is adapted to mount at a gun barrel muzzle, the
moderator having a body, the body having a longitudinal axis and
having a moderator cylinder wall having an internal surface within
which are a plurality of moderating stages, each stage having (A) a
baffle formed across and inside the cylinder wall and having a
concentric hole which is concentric with the moderator cylinder
wall; and (B) a deflector adapted to deflect gas flow from the
concentric hole to move with a radial component so as to impact the
internal surface of the moderator cylinder wall and be guided for
circulation around the same.
[0007] Advantageously, the gas leaving the barrel upon firing a
projectile from the gun is deflected within the body such that the
gas is deflected to move with a radial component out to and in and
around the internal surface of the cylinder wall of the body before
finally exiting the moderator. The motion of gas flow around the
internal surface of the cylinder wall may substantially or at least
generally or partly comprise a toroidal motion. This allows for a
much smaller and lighter gun sound moderator than those available
in the prior art that with the same, or better, report/noise
reducing properties.
[0008] The report/noise of a gun is a result of the pressure wave
generated by the high-pressure, hot gas leaving the barrel of the
gun at the muzzle upon firing a round/projectile from the gun, for
example a rifle or other cartridge. Reduction in the
pressure/volume of the gas has a relationship in the reduction of
the report/noise of the gun.
[0009] The gas may be emitted from a hole through a baffle as a
generally conical jet, then being deflected within the moderator so
as to have a radial motion, or a motion first with a radial
component outwardly to the internal wall, and then a circulatory or
toroidal motion around inside the internal wall, within the body of
the moderator so as to work to reduce the report/noise by two
means. Firstly, the gas passing through the moderator spends more
time than in prior art moderators in contact with the material of
the moderator, cooling the gas. Rotating the gas around inside the
moderator, rather than merely interfering with its progress within
the moderator, ensures that the gas, which is hot since it is a
product of exothermic chemical reaction due to firing of the
cartridge or round, spends more time than in prior art moderators
in contact with the material of the construction of the moderator,
particularly of the moderator cylinder wall where heat transfer to
the atmosphere may occur, and the gas is therefore cooled further
than would normally be possible in a given volume with known gun
sound moderators. The radial movement and circulation of the gas
and the internal construction of the moderator ensure that the hot
gas spends as much time as possible within the external moderator
cylinder wall of the moderator. It is the external surface of the
moderator cylinder wall which has the greatest ability to lose heat
due to its direct contact with ambient temperature air which allows
the gun sound moderator to continue to work efficiently. Cooling
the gas reduces its volume, as described by Charles's law. The
volume of gas can approximate to being proportional to the
temperature of the gas and reducing the temperature of the gas
within the gun sound moderator reduces the volume of the gas and
therefore the pressure wave which creates the report/noise.
Secondly, deliberately rotating the gas within the gun sound
moderator ensures that the gas is retained within the body of the
gun sound moderator before finally exiting in a controlled way over
a greater period of time compared to that of the uncontrolled
release from a gun barrel alone.
[0010] The deflectors in different stages inside the gun sound
moderator may be positioned rotated apart relative to one another
at each stage. However, they may not be. The deflectors in at least
one said stage may be arranged to cause a circulatory or toroidal
gas flow within the moderator which is in a clockwise direction, or
in an anti-clockwise direction, when seen looking along in the
forward direction of movement of a projectile through the
moderator. Different stages within the moderator may rotate the gas
in opposite directions in some embodiments.
[0011] When deflectors in different stages are positioned rotated
apart relative to one another, the deflectors may serve a second
purpose in addition to their deflection function: the deflectors
may be structural. In particular, when stages have baffle plates
extending across a body of the moderator, the deflectors may ensure
that substantially all of the area of each baffle plate is
supplemented in thickness by the deflectors, noting that the
deflectors may be located on both sides of the baffles plates to
achieve this. Thus, the deflectors may serve to enable a core of
the moderator to withstand the substantial pressures generated when
firing projectiles.
[0012] Each stage may have one or more than one said deflector. In
this case, the gun sound moderator may have two said deflectors at
each stage which are positioned angularly rotated 180.degree.
relative to one another about the longitudinal axis of the
body.
[0013] Each deflector, when viewed cutaway in a direction from a
side of the body, may look straight and angled at approximately
45.degree. to the longitudinal axis of the body. Alternatively,
each deflector may be curved and with a radius in a section viewed
across the longitudinal axis of the body.
[0014] According to a further aspect hereof, there is provided a
gun having a gun barrel with a muzzle and a gun sound moderator as
set out in the first aspect hereof mounted at the muzzle.
[0015] According to a further aspect hereof, a gun sound moderator
has an external moderator cylinder wall inside which is a series of
stages, each having a baffle formed with a concentric hole which is
concentric with the cylinder wall and a deflector, gas passing
through the concentric hole being deflected by the deflector so as
to move with a radial component towards and then to move with a
circulatory motion along/around inside the moderator cylinder wall
so as to achieve improved heat transfer from the gas through the
moderator cylinder wall and into the ambient atmosphere outside the
gun sound moderator so as to achieve cooling of the gas so as to
reduce its volume and controlled gas release to atmosphere, so as
to achieve a relatively quiet report/noise when a projectile is
fired through the gun sound moderator.
[0016] A further aspect provides a gun sound moderator which is
adapted to mount at a gun barrel muzzle, the moderator having a
body, the body having a longitudinal axis and having a moderator
external wall having an internal surface within which is at least
one moderating stage, each stage having (A) a baffle formed across
and inside the external wall and having a gas passage formed for
the flow of gas therepast; and (B) a deflector adapted to deflect
gas flow from the gas passage to move so as to flow towards the
inside of the moderator external wall and be guided for circulation
around the same.
[0017] The moderator external wall may be cylindrical, such as
circularly cylindrical. In other embodiments it may be tapered or
stepped in cross-dimension or diameter.
[0018] The gun sound moderator may include a plurality of said
stages.
[0019] The gas passage may comprise a hole formed through the
baffle and concentric with a centre longitudinal axis of the body
of the gun sound moderator.
[0020] Each deflector may include a first wall surface which is
curved, for example concave, so as to deflect gas travelling from
the hole towards the external wall. In this case, the first wall
surface may be an at least part circularly cylindrical first wall
surface and oriented with a longitudinal direction thereof
substantially perpendicular to the central longitudinal axis of the
body. The first wall surface may be curved in other ways in other
embodiments such as by having a parabolic or hyperbolic cross
section, or a curved cross section which varies in a radial and/or
axial direction.
[0021] Each deflector may include a second wall surface which is
planar or substantially planar and which is oriented substantially
parallel to the longitudinal direction of the at least part
circularly cylindrical first wall surface.
[0022] Each deflector may include a second wall surface which is
planar or substantially planar and which is oriented substantially
parallel to the longitudinal axis of the body.
[0023] Each deflector may include a third wall surface, the third
wall surface together with the external wall forming a passage
therebetween for the flow of gas therethrough with a circulatory or
rotational motion around inside and guided by the external
wall.
[0024] The third wall surface may have a curved profile and may
substantially comprise part of a surface of revolution whose
imaginary axis of rotation is on a convex side of the curved
profile.
[0025] The curved profile may be substantially semi-circular.
[0026] The gun sound moderator may have a toroidal passage formed
within the body for toroidal gas flow therethrough, the passage
including at least one flow guide extending along within the
toroidal passage.
[0027] The at least one flow guide may comprise a fin or vane.
[0028] The fin or vane may be generally planar.
[0029] At least one said fin or vane may extend in a direction
generally perpendicular to or perpendicular to the longitudinal
axis of the body, or may be oriented at a slant thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 shows a side cutaway view of a typical known prior
art gun sound moderator with baffles, together with a gun
barrel/muzzle;
[0031] FIG. 2 shows a side cutaway schematic view of a first
embodiment of a gun sound moderator in accordance with the
invention;
[0032] FIG. 3 shows a schematic end view cross-section along a
longitudinal axis of the moderator shown in FIG. 2;
[0033] FIG. 4 schematically shows part of a gun sound moderator as
shown in FIGS. 2 and 3, but with a modified deflector;
[0034] FIG. 5 shows an isometric view of part of a second
embodiment of a gun sound moderator in accordance with the
invention;
[0035] FIG. 6 shows a further isometric view of the gun sound
moderator of FIG. 5;
[0036] FIG. 7 shows a gun with a gun sound moderator as shown in
FIGS. 2 and 3, or as modified with reference to FIG. 4 or as in
FIGS. 5 and 6, mounted at the muzzle of the gun barrel thereof;
[0037] FIG. 8 schematically shows in isometric a section, in a
plane coincident with a longitudinal axis of a body of the gun
sound moderator of FIGS. 5 and 6, through a toroidal flow path of
gas within a stage of the gun sound moderator; and
[0038] FIG. 9 shows a schematic side elevational cross section
through the gun sound moderator of FIGS. 5, 6 and 8, modified by
the inclusion of flow-guiding fins within a toroidal flow passage
thereof.
DETAILED DESCRIPTION
[0039] FIG. 1 shows a gun barrel 10 with a gun barrel muzzle 12 and
a typical known baffled gun sound moderator 14 with baffles 16, the
gun sound moderator 14 being mounted at the gun barrel muzzle 12.
Upon firing a projectile 20 with a direction of travel
(longitudinal moderator axis) 22 through the gun barrel 10 and gun
sound moderator 14, high velocity hot gas with a direction of
travel depicted by arrows 24 passes through the gun sound moderator
14 with turbulent gas flow as depicted by arrows 26. As the gas
from the gun barrel 10 exits the barrel 10 and passes within the
moderator 14, it expands, approximated to a cone (as shown by
arrows 24) in FIG. 1, with a velocity in the direction of an exit
28 of the gun sound moderator 14 furthest from the gun barrel
muzzle 12. The baffles 18 within this typical known moderator
"strip" the high velocity gas from the projectile 20, as shown
schematically in FIG. 1.
[0040] In one embodiment in accordance with the invention as shown
in FIG. 2, a gun sound moderator 30 with baffles 32 is mounted to a
gun barrel muzzle 34 of a gun barrel 36 and is provided with
deflectors 38 whereby, when a projectile 40 with direction of
travel 42 is fired through the gun barrel 36 and gun sound
moderator 30, along a longitudinal axis 44 of the gun sound
moderator 30, gas flows from concentric hole 46 in a baffle 32 of
the gun sound moderator 34 first along arrow 1 to deflector 38 then
is deflected off the deflector 38 in a radial direction 2, or at
least a direction with a radial component. Then, as shown in FIG.
3, the gas is, as shown by arrow 3, subjected to circulation around
and guidance from an internal surface 48 of moderator cylinder wall
50 with an external surface 52.
[0041] Thus, as shown in FIG. 3, at least some of the gas, upon
firing the projectile 40, exits the concentric hole 46 generally in
the form of a conical jet and travels along as schematically
depicted by arrow 1, at least some of the gas impacts radial
deflectors 38 and changes direction so as generally to have a
radial component travelling generally in the direction depicted by
arrow 2. At least some of this flow then impacts the internal
surface 48 of the moderator cylinder wall 50 to be deflected to
provide at least some of the gas with a generally circulatory or
toroidal motion or a circulation guided from internal surface 48 of
moderator cylinder wall 50, before passing to a next stage 54 of
the gun sound moderator 34 with a further baffle 32 and deflectors
38.
[0042] For clarity in FIG. 2, the deflectors 38 are shown in the
same plane but they may be positioned rotated apart at each stage
54 or have more than one deflector 38 in each stage 54. FIG. 3
shows two deflectors 38 which are located 180.degree. apart with
respect to one another. Each stage 54 includes a baffle 32 with its
concentric hole 46 and the downstream part of the cylinder wall and
deflectors 38 before the next baffle 32.
[0043] FIG. 2 shows the deflectors 38 as approximately 45.degree.
straight items. In practice, these can be shaped and angled for
better efficiency by looking at the multiple angles of the gas flow
expanding through the concentric hole 46. Each angle will have a
corresponding angle to which the deflector is shaped so as to
ensure that the gas is deflected in a radial fashion at an
approximately 90.degree. angle to the movement of the projectile
40. In practice, this means that the deflector may be curved in
shape and for the purposes of making a practical gun sound
moderator is a radius.
[0044] This is shown in FIG. 4 with only a single stage 54 for
clarity. FIG. 4 shows the projectile 40 with direction of travel 42
and the embodiment has radial deflectors 38, so this is an example
of an advanced shape of the radial deflector 38 and shows how gas
is sufficiently directed to travel in a radial way inside a single
stage 54 of the gun sound moderator 30.
[0045] In a further embodiment in accordance with the invention,
FIG. 7 shows a gun sound moderator body 100 mounted to a muzzle 102
of a barrel 104 of a gun 106. FIGS. 5 and 6 show the body with a
circularly cylindrical external wall 108 thereof removed to reveal
a central core 110 thereof. The central core 110 includes a
threaded attachment mounting flange 112 for mounting the body 100
to the muzzle 102 and a set of four angularly spaced tension arms
114 connecting the flange 112 to a first of four baffle plates 110,
each baffle plate 110 having a circular edge 134 which, together
with a circular outer edge of the flange 112 and an exit flange 130
may be sealingly engaged against the inner surface 101 of the
circularly cylindrical external wall 108, using mechanical or other
means (not shown). The moderator body is therefore preferably
sealed apart from where the projectile enters and leaves it.
[0046] The arms 114 form a pre-chamber 116 whose design may vary in
other embodiments, for example extending back over the muzzle 102.
The pre-chamber may thus form a pressurisable plenum in advance of
the moderating stages of the moderator.
[0047] Each baffle plate 110 comprises a circular disc with a
central hole 120 passing through it for the passage of hot gas
through the moderator body 100. Each baffle plate 110 is part of a
stage 103 of the moderator body 100 which also includes two
deflectors 105 linking the stage to the next downstream stage or
the final exit flange 130. The two deflectors 105 of each stage 103
are the same as one another and positioned rotated angularly
180.degree. relative to one another. The deflectors 105 of adjacent
stages are positioned rotated angularly 90.degree. relative to one
another. This can enable the material of the deflectors to perform
a second task in addition to gas deflection, namely to provide
mechanical strength to the core of the moderator by ensuring
relatively thick material, so a strong construction, in all regions
of each baffle plate 110. These constructions could differ in other
embodiments. For example, three deflectors could be provided
located 120.degree. apart from one another. Each stage could have
different numbers of deflectors, e.g. any number between one and
about six, and the deflector(s) in different stages may have
different axial lengths and dimensions to one another.
[0048] Each of the two deflectors in FIGS. 5 and 6 has three wall
surfaces 122, 124 and 126.
[0049] The first wall surface 122 is curved and this surface is
substantially part of the surface of an imaginary circular
cylinder, the axis of which is perpendicular to or substantially
perpendicular to and may substantially intersect with or actually
intersect with the longitudinal axis 127 of the body 100. The
diameter of the imaginary cylinder may be substantially the same as
the distance between the baffle plates 110 located adjacent each
deflector 105.
[0050] The second wall surface 124 also has a curved profile and
comprises part of an imaginary surface of revolution whose centre
is on a convex side of the curved profile (and may be on the
longitudinal axis 127 of the body 100), the curved profile
optionally being substantially semi-circular, in which case the
diameter of the curved profile is or may be substantially the same
as or the same as the distance between the baffle plates 110
located adjacent each deflector 105. The second wall surface 124
together with the interior surface 101 of the external cylindrical
wall 108 therefore forms a passage 129 between these surfaces for
the flow of gas therethrough with a circulatory rotational motion
around inside and guided by the inside surface 101 of the external
wall 108.
[0051] The third wall surface 126 is substantially planar or
planar, lying parallel to or substantially parallel to the
longitudinal axis 127 of the body 100. The plane of the third wall
surface 126 may also be substantially perpendicular to the axis of
the imaginary circular cylinder of the first wall surface 122.
Parallel to the third wall surface 126 but facing oppositely is an
optional relatively small planar eyelid-shaped surface 128 on each
deflector which intersects with the curved first wall surface 122.
The purpose of surface 128 is to split, separate and hold apart the
respective gas flows flowing towards different deflectors 105. This
therefore helps ensure that the gas flows to the intended
deflectors 105. The surface 128 may have other shapes in other
embodiments. Dependent upon geometry of the size or stages and the
number of deflectors, the surface 128 may be employed to enhance
noise reduction, being sometimes used but not necessarily always in
every stage. The surface 128 may be omitted entirely in some
embodiments or merely from one or more stages.
[0052] As depicted by flow path arrow 140, high-pressure gas
passing through each central hole 120 may first have an
outwardly-flaring first path 142 to the first wall surface 122 from
where it is deflected on a second path 144 with a radial component
out to where it reaches the interior surface 101 of the cylindrical
external wall 108 and is deflected into a circulatory or rotational
motion path 146 along the interior wall 101 and through the passage
129 before passing radially inwardly again and out through the next
central hole 120 of the moderator body 100 in one of the baffle
plates 110 or the end flange 130. The circulation of the flow,
including through the passage 129, ensures good cooling of the flow
and therefore a reduced report (noise) when the gun 106 is
fired.
[0053] As flow arrow 148 shows, flow exiting the internal hole 120
in the direction of the planar third wall surface 126 of each
deflector is not significantly deflected by the third wall surface
126 because the third wall surface 126 substantially intersects
with the longitudinal axis 127 and this flow is therefore drawn
around into the passage 129 together with the flow which has been
deflected by the curved first wall surface 122. Although some of
the flow passing generally along the flow arrow 140 or alongside it
may mix with flow exiting from the second of the two passages 129
in the same stage 103, the construction overall permits a
substantial rotational circulation of flow which is toroidal in
nature and/or form around the passages 129 before the pressure
differential across the stage 103 and between the stage 103 and to
the next stage 103 forces the flow to move radially inwardly and
out through the next central hole 120. The way in which the planar
third wall surface 126 of one deflector is adjacent to the curved
first wall surface 122 therefore assists in causing rotational flow
around through the two passages 129 of each stage 103. The toroidal
flow is highly advantageous, permitting significant heat transfer
from the gas within the moderator out to atmosphere by means of
conduction outwardly through the external wall, which may conduct
heat very well, such as when made of an aluminium alloy. The body
of the moderator including the baffle plates 110 and deflectors 105
may also be formed of such material.
[0054] It is noted that the deflectors 105 have a second purpose,
above deflection, which is structural: the deflectors 105 join
baffle plates 110 of the core together and take substantial load in
tension to hold the core together when the gun 106 is fired.
[0055] The construction described with respect to FIGS. 5 to 7
permits a gun sound moderator which is small and light yet which
has good performance in moderating or attenuating the report of a
gunshot and the shot is not heard so easily so as to limit the
sound of the shot in the surrounding area. Although a supersonic
projectile fired from the gun 106 may still create significant
noise due to the shockwave caused by supersonic flight through air,
the noise experienced by the operator firing the gun is
substantially reduced.
[0056] The moderator body 100 shown in FIG. 7 may be replaced on
the gun 106 if desired by the arrangement shown and described with
reference to FIGS. 2 and 3 above, or as modified with reference to
FIG. 4.
[0057] FIG. 8 schematically shows in isometric a section, through a
plane coincident with a longitudinal axis 127 of a body of the gun
sound moderator of FIGS. 5 and 6, a toroidal flow path of gas
within a stage 103 of the gun sound moderator next to the inner
surface 101 of the external wall 108. The section through the
toroidal flow path is D-shaped but may have other shapes in other
embodiments.
[0058] With the gun barrel 104 rifled so as spin the projectile,
all of the deflectors 105 may be configured to create the toroidal
gas spin round and through the passages 129 in the same rotational
direction as the direction of projectile spin. However, in other
embodiments only some deflectors may do so and some or all
deflectors may create similar gas rotation in the opposite
direction to projectile spin caused by rifling.
[0059] FIG. 9 shows how the passage 129 may be provided with one or
more flow fins or vanes 200, 202, dotted for the purposes of
clarity in FIG. 9 but in practice which may or may not be solid
plates or the like, aligned with the direction of intended toroidal
circulatory flow. The fins 200, 202 may be planar or curved and at
least when planar may be aligned perpendicular to the longitudinal
axis of the moderator body or at a slant to it as shown
schematically in FIG. 9. One or more fins or vanes 200, 202 in the
direction of toroidal gas flow depending on stage geometry enhances
sound reduction.
[0060] Various modifications may be made to the embodiments
described without departing from the scope of the invention.
[0061] Various modifications may be made to the embodiments
described without departing from the scope of the invention.
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