U.S. patent number 3,667,570 [Application Number 05/019,829] was granted by the patent office on 1972-06-06 for silencers for firearms, internal combustion engines, or the like.
This patent grant is currently assigned to Michael H. Adair, Rosser S. Reeves, III. Invention is credited to Mitchell L. WerBell, III.
United States Patent |
3,667,570 |
WerBell, III |
June 6, 1972 |
SILENCERS FOR FIREARMS, INTERNAL COMBUSTION ENGINES, OR THE
LIKE
Abstract
Silencers for use in conjunction with firearms and as mufflers
for internal combustion engines and the like are provided with
entry, suppression and resonant chambers arranged coaxially within
a tubular housing. A plurality of helical suppressor elements are
axially disposed in the suppression chamber and arranged in
opposition to each other. The entry and resonate chambers may be
provided with baffles. The entry chamber may be provided with an
excess pressure relief valve. Orificed resilient plugs may be
provided in the vicinity of the discharge end of the silencer
particularly for use in conjunction with firearms. At the entry end
of the silencer there may be provided a tube with an L-shaped slot
permitting ready mounting of the silencer on the barrel of a
firearm.
Inventors: |
WerBell, III; Mitchell L.
(Powder Springs, GA) |
Assignee: |
Adair; Michael H. (New York,
NY)
Reeves, III; Rosser S. (New York, NY)
|
Family
ID: |
26692659 |
Appl.
No.: |
05/019,829 |
Filed: |
March 16, 1970 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
700239 |
Jan 24, 1968 |
3500955 |
Mar 17, 1970 |
|
|
Current U.S.
Class: |
181/223;
89/14.4 |
Current CPC
Class: |
F41A
21/30 (20130101) |
Current International
Class: |
F41A
21/00 (20060101); F41A 21/30 (20060101); F41f
017/12 (); F41c 021/18 (); F01n 001/08 () |
Field of
Search: |
;89/14,14.2,14.3,14.4
;181/36,36.4,44-46,47,57,58,68,70,72,47.1,64.2,65,37,45,66,67,33A,61 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
493,462 |
|
May 1919 |
|
FR |
|
317,577 |
|
Dec 1919 |
|
DD |
|
629,404 |
|
Apr 1936 |
|
DD |
|
6,701 |
|
1899 |
|
GB |
|
498,775 |
|
Jan 1939 |
|
GB |
|
581,974 |
|
Oct 1946 |
|
GB |
|
242,743 |
|
Nov 1925 |
|
GB |
|
Primary Examiner: Ward, Jr.; Robert S.
Parent Case Text
This is a continuation-in-part of U.S. Pat. application Ser. No.
700,239, filed Jan. 24, 1968, now U.S. Pat. No. 3,500,955, issued
Mar. 17, 1970.
Claims
What is claimed is:
1. In a firearms silencer adapted to be mounted on a firearm in
alignment with the firing chamber of the firearm to receive a
bullet discharged from the firing chamber and comprising means
defining a passage for the discharged bullet, the improvement
comprising positioned in the passage a plug of a resilient material
having therethrough in axial alignment with the passage a circular
orifice of smaller diameter than the bullet and at least one radial
cut communicating with the orifice, the radial cut together with
the radius of the orifice being at least equal to the radius of the
bullet, the resiliency of the material and the radial cut
permitting the discharged bullet to pass through the orifice.
2. In the firearms silencer improvement according to claim 1, a
second radial cut communicating with the orifice, said second
radial cut being of length at least equal to that of the first
radial cut and in diametrical opposition to the first radial
cut.
3. In a firearms silencer adapted to be mounted on a firearm in
alignment with the firing chamber of the firearm to receive a
bullet discharged from the firing chamber and comprising means
defining a passage for the discharged bullet, the improvement
comprising positioned in the passage a first plug of a resilient
material having therethrough in axial alignment with the passage an
orifice of smaller diameter than the bullet, the resiliency of the
material permitting the discharged bullet to pass through the
orifice, and a second plug of a resilient material abutting against
the bullet exit side of the first plug and having therethrough in
axial alignment with the orifice through the first plug an orifice
of larger diameter than the bullet.
4. In a firearms silencer improvement according to claim 3, a third
plug of a resilient material having therethrough in axial alignment
with the orifice through the second plug an orifice of smaller
diameter than the bullet, the resiliency of the material of the
third plug permitting the bullet to pass through the orifice of the
third plug, and a fourth plug of a resilient material abutting
against the bullet exit side of the third plug and having
therethrough in axial alignment with the orifice of the third plug
an orifice of larger diameter than the bullet.
5. In a firearms silencer improvement according to claim 3, in
which the first plug is provided with at least one radial cut
communicating with the orifice of the first plug, the radial cut
together with the radius of the orifice being at least equal to the
radius of the bullet, the radial cut assisting in the permitting of
the discharged bullet to pass through the orifice of the first
plug.
6. In a firearms silencer improvement according to claim 5, in
which the first plug is provided with a second radial cut
communicating with the orifice, said second radial cut being of
length at least equal to that of the first radial cut and in
diametrical opposition to the first radial cut.
7. In a firearms silencer improvement according to claim 4, in
which the third plug is provided with at least one radial cut
communicating with the orifice of the third plug, the radial cut
together with the radius of the orifice being at least equal to the
radius of the bullet, the radial cut assisting in the permitting of
the discharged bullet to pass through the orifice of the third
plug.
8. In a firearms silencer improvement according to claim 7, in
which the third plug is provided with a second radial cut
communicating with the orifice, said second radial cut being of
length at least equal to that of the first radial cut and in
diametrical opposition to the first radial cut.
9. A silencer comprising aligned entry and suppression chambers,
the suppression chamber containing helical suppressor elements and
the entry chamber being upstream from the suppression chamber, in
the entry chamber at least one baffle comprising a plate having an
aperture therethrough surrounded by a wall which arcuately flares
outwardly to define increasingly greater diameters of the aperture
as the distance from the baffle to the suppression zone
decreases.
10. A silencer comprising aligned suppression and resonance
chambers, the resonance chamber being positioned downstream from
the suppression chamber, a plurality of helical suppressor elements
disposed coaxially in the suppression chamber with adjacent helical
elements arranged in opposition to each other, means defining an
axial passageway through said helical elements and a plurality of
radial ports by which communication is established between said
passageway and said helical elements, said ports being spaced
axially along said passageway whereby gaseous material in said
passageway is supplied sequentially to said helical elements
through said ports so that self-neutralizing opposed vibrations are
produced, at least one baffle positioned in the resonance chamber,
the baffle comprising a plate having an aperture therethrough
surrounded by a wall which arcuately flares outwardly to define
increasingly greater diameters of the aperture as the distance from
the baffle to the suppression zone increases.
11. A silencer according to claim 9, in which a plurality of said
baffles are positioned in the entry chamber.
12. A silencer according to claim 10, in which a plurality of said
baffles are positioned in the resonance chamber.
13. A silencer comprising aligned entry, suppression and resonance
chambers, the suppression chamber containing helical suppressor
elements, the entry chamber being upstream from the suppression
chamber and the resonance chamber being downstream from the
suppression chamber, a plurality of baffles positioned in each of
the entry chamber and resonance chamber, each of the baffles
comprising a plate having an aperture therethrough surrounded by a
wall which arcuately flares outwardly to define increasingly
greater diameters of the aperture, the baffles in the entry chamber
being so oriented that the diameter of the aperture of a respective
baffle increases as the distance from the baffle to the suppression
chamber decreases and the baffles in the resonance chamber being so
oriented that the diameter of the aperture of a respective baffle
increases as the distance from the baffle to the suppression
chamber increases.
14. A silencer according to claim 13, further comprising a
plurality of helical suppressor elements disposed coaxially in the
suppression chamber with adjacent helical elements arranged in
opposition to each other, means defining an axial passageway
through said helical elements and a plurality of radial ports by
which communication is established between said passageway and said
helical elements, said ports being spaced axially along said
passageway whereby gaseous material in said passageway is supplied
sequentially to said helical elements through said ports so that
self-neutralizing opposed vibrations are produced.
15. A silencer according to claim 14, further comprising a tubular
outer housing defining the outer wall of the aligned chambers and
wherein the thickness of the housing irregularly varies along the
length thereof.
16. A silencer according to claim 14 further comprising a relief
valve communicating between the interior of the entry chamber and
the exterior of the suppressor.
17. A silencer according to claim 14, further comprising a mounting
means in the form of a hollow element defining the entry end of the
silencer and in axial alignment with the entry chamber, said hollow
element being provided with a L-shaped slot having a longitudinal
arm parallel to the axis of the element and opening at the free end
of the element and a second arm communicating with the longitudinal
arm and being oriented at right angles to the longitudinal arm.
18. A firearms silencer according to claim 14, further comprising
positioned in the resonance chamber a plug of resilient material
having therethrough in axial alignment with the passage an orifice
of smaller diameter than the bullet to be discharged from the
firearm and at least one radial cut communicating with the orifice,
the radial cut together with the radius of the orifice being at
least eaual to the radius of the bullet, the resiliency of the
material and the radial cut permitting the discharged bullet to
pass through the orifice.
19. A firearms silencer according to claim 18, in which the plug is
provided with a second radial cut of length at least equal to that
of the first radial cut and in diametrical opposition to the first
radial cut.
20. A firearms silencer according to claim 17, further comprising
positioned in the resonance chamber a first plug of resilient
material having therethrough an orifice of smaller diameter than
the bullet to be discharged by the firearm, the resiliency of the
material permitting the discharged bullet to pass through the
orifice, and a second plug of resilient material abutting against
the bullet exit side of the first side and having therethrough in
axial alignment with the orifice through the first plug an orifice
of larger diameter than the bullet.
21. A firearms silencer according to claim 20, further comprising
in the resonance chamber a third plug of resilient material having
therethrough in axial alignment with the orifice through the second
plug an orifice of smaller diameter than the bullet, the resiliency
of the material of the third plug permitting the bullet to pass
through the orifice of the third plug, and a fourth plug of
resilient material abutting against the bullet exit side of the
third plug and having therethrough in axial alignment with the
orifice of the third plug an orifice of larger diameter than the
bullet.
22. A firearms silencer according to claim 21, in which the first
plug and the third plug are each provided with at least one radial
cut communicating with the orifice of the respective plug, the
radial cut together with the radius of the orifice of the
respective plug being at least equal to the radius of the bullet,
the radial cut assisting in the permitting of the discharged bullet
to pass through the orifice of the respective plug.
23. In a silencer comprising a housing having an entry end and
containing helical suppressor elements and a discharge end, the
improvement comprising non-uniform variations of the thickness of
the housing.
24. In a silencer comprising aligned entry and suppression
chambers, the suppression chamber being downstream from the entry
chamber and containing helical suppressor elements, the improvement
comprising a relief valve communicating between the interior of the
entry chamber and the exterior of the silencer.
25. In a silencer improvement according to claim 24, in which the
relief valve comprises means defining a conduit communicating
between the interior and the exterior of the silencer, closure
means for the conduit mounted for reversible movement from a closed
position to an open positon and spring means biasing the closure in
a closed position toward the interior of the entry chamber.
26. In a silencer improvement according to claim 25, in which the
closure comprises a wall.
27. In a silencer improvement according to claim 24, in which the
relief valve comprises means defining a tortuous and constricted
path between the interior of the entry chamber and the exterior of
the silencer.
Description
This invention relates to silencers for use in conjunction with
firearms and as a muffler for internal combustion engines and, more
generally, in any instance in which it is desired to decrease the
level of noise carried by a fluid. The silencers of the present
invention are particularly adapted to decreasing the sound level
resulting from the sudden expansion of a gas.
A silencer constructed according to one embodiment of this
invention may comprise a plurality of helical suppressor elements
disposed about an axial passageway together with a plurality of
radially disposed ports arranged to establish communication from
the passageway to the suppressor elements so that out-of-phase
vibrations are supplied from the axial passageway to the suppressor
units in such manner as substantially to neutralize each other. A
suppression chamber is disposed adjacent to and in axial alignment
with the suppression chamber and is provided with end walls having
concave inwardly dished inner surfaces and an inwardly protruding
throat portion is formed on the inner surface of the outer end
wall, the resonant chamber being effective to damp and
substantially to silence any unneutralized frequencies which escape
from the suppression chamber. An entry chamber, disposed within the
tubular outer housing and between the muzzle of the associated gun
barrel and the entry end of the suppressor chamber functions as a
pressure reducing chamber for supplying gaseous material to the
suppression chamber following expulsion from the muzzle of the gun
barrel.
According to another aspect of the invention, in the entry and/or
the resonance chamber there may be positioned at least one and
preferably a plurality of baffles each comprising a plate having an
aperture therethrough surrounded by a wall which arcuately flares
outwardly to define increasing diameters of the aperture. When such
a baffle is positioned in the entry chamber, it is oriented so that
diameter of the aperture increases as the distance from the baffle
to the suppression zone decreases. Conversely, when such a baffle
is placed in the resonance chamber, it is oriented so that the
aperture diameter increases as the distance from the baffle to the
suppression chamber increases. It is found that such baffles,
particularly in conjunction with the helical element containing
suppression zone provide greater suppression of sound. Insofar as
firearms are concerned, this baffle is particularly useful in
suppressors for higher caliber rifles and automatic weapons.
A further feature of the present invention is directed to greatly
decreasing or eliminating the popping sound characteristic of a
bullet discharging from a bore in alignment with the firing chamber
of the firearm. To this end there is provided near the discharge of
the silencer a plug of a resilient material, such as a rubber or a
polyurethane or other resilient plastic. Through the plug is
provided an aperture for passage of the bullet. The aperture is of
diameter smaller than the bullet. The resiliency of the material of
the plug permits passage of the bullet through the aperture. In a
preferred embodiment, the plug is provided with at least one radial
cut communicating with the orifice, the cut together with the
radius of the orifice being at least equal to the radius of the
bullet whereby the cut aids the passage of the bullet through the
aperture and increases the useful life of the plug. Preferably,
there is provided at least one diametrically opposed pair of such
radial cuts. Moreover, against the discharge side of this first
plug may be provided a second plug of a resilient material, the
second plug having an orifice of greater diameter than the bullet.
The second plug acts as a backup for the first plug. Specifically,
the passage of the bullet through the orifice of the first plug
causes the first plug to protrude into the orifice in the second
plug. The support provided by the second plug helps decrease any
tendency of the first plug to shear during passage of the bullet.
There may be provided two or more abutting pairs of these
plugs.
In yet another aspect of the invention, there is provided a
mounting means for a silencer which utilizes the front sight on the
barrel of a firearm for retaining the silencer on the firearm. This
feature is particularly useful for use in conjunction with pistols.
More particularly, at the entry end of the silencer is provided a
tubular element of diameter slightly greater than the diameter of
the barrel of the firearm and having a L-shaped slot. One arm of
the L extends parallel to the axis of the tubular element, opens at
the end of the tubular element which is free when the tubular
element is associated with a silencer and is of a width at least
slightly greater than the width of the front sight of the firearm
in a direction perpendicular both to the axis of the barrel of the
firearm and the height of the sight. At its opposite end this arm
of the L-shaped slot communicates with the other arm of the
L-shaped slot. The other arm is of a width taken on a line parallel
to the axis of the tubular element at least slightly greater than
the length of the front sight.
Hence, the tubular element carrying at its far end the suppressor
is slid onto the barrel of the firearm with the front sight of the
firearm being guided in the longitudinal arm of the slot and when
the second arm of the slot is adjacent the front sight the entire
silencer assembly including the tubular element is rotated in a
direction counter to the direction in which the second arm extends
from the first arm whereby the front sight is received in the
second arm and the silencer is thereby prevented from being slid
from the barrel of the firearm. Preferably, relatively snug fit is
provided between the front sight and the second arm in order that
the silencer not inadvertently be rotated to a position in which it
may slide off the barrel.
In another feature of the invention, there is provided in
communication with the interior of the silencer an excess pressure
relief valve. This valve communicates preferably with the entry
chamber of the silencer. The valve may be provided with a spring
biased closure or may operate on a principle of provision of small
cross section tortuous passages for the escaping gas whereby
provision of moving parts may be avoided.
The invention will now be further described with reference to the
accompanying drawing in which:
FIG. 1 is a side view of a rifle to the muzzle of which a silencer
constructed according to this invention is affixed;
FIG. 2 is an enlarged cross-sectional view of a silencer
constructed according to the invention;
FIG. 3 is an exploded view depicting the internal parts of the
silencer in perspective after their removal from the tubular outer
housing;
FIG. 4 is an enlarged cross-sectional view of one of the suppressor
elements depicted in FIGS. 2 and 3;
FIG. 5 is an enlarged cross-sectional view of an axially apertured
partition which separates the entry chamber from the suppression
chamber;
FIG. 6 is a cross-sectional view of another silencer constructed
according to the invention;
FIG. 7 is an isometric view of means according to the invention
mounting a silencer on the barrel of a firearm;
FIG. 8 is a modification of the entry chamber in a silencer such as
of FIG. 2 to incorporate baffles according to the invention;
FIG. 9 is a modification of a resonance chamber in a silencer as of
FIG. 2 to incorporate baffles according to the invention; and
FIGS. 10 and 11 are relief valves according to the invention to be
incorporated in a silencer.
In FIG. 1 the numeral 1 designates generally a rifle to which a
silencer generally designated by the numeral 2 is affixed.
Silencer 2 as best shown in FIG. 2 comprises an outer housing 3
which is internally threaded along a substantial portion of its
inner surface and which therefore is adapted to receive the inner
elements which constitute principal features of the invention.
At the entry end of tubular outer housing element 3, an entry
chamber 4 is defined by flanged end wall element 5 which is
externally threaded as indicated at 8 for cooperation with the
internal threads of tubular outer housing 3. End wall 5 is
internally threaded as indicated at 6 for receiving external
threads formed on the exterior surface of the muzzle of the barrel
of gun 1. A flange 7 forms an abutment ledge for engagement with
the end of tubular outer housing 3.
At the opposite end of the entry chamber 4, an axially apertured
partition 9 is disposed. Partition 9 is provided with external
threads 10 which cooperate with the inner threads of tubular outer
housing 3. The axial aperture 11 formed in partition 9 is of
progressively diminishing diameter and is of stepped configuration
as indicated at 12.
Thus as a projectile passes through the entry chamber in the
direction indicated by the arrow A, relatively high pressure gas is
admitted to the entry chamber as the projectile (bullet) clears the
muzzle of the gun barrel. Similarly, when the device is employed as
a muffler for an internal combustion engine, relatively high
pressure gas would be admitted into the entry chamber. This high
pressure gas is allowed quickly to expand and then to pass through
the aperture 11, in the case of use with a firearm as the
projectile completes its passage through partition 9.
The suppression chamber constructed according to this invention is
defined at its ends by partition 9 and by partition 14. Partition
14 is externally threaded as designated at 15 and hence may be
adjustably mounted with the tubular outer housing 10 in any desired
axial position by simply rotating the partition 14 and thus causing
axial movement thereof.
In order to provide for the application of out-of-phase vibrations
to the oppositely disposed reversely wound helical suppressor
elements 16-20 inclusive, a plurality of radial ports designated by
the numerals 21-30 are spaced along passageway 13 so that these
ports are progressively uncovered. Fluid is thus admitted first
through radial port 30 and subsequently through radial port 29 and
so on as the fluid proceeds from right to left as viewed in FIG. 2.
Frequencies which are characteristic of the fluid adjacent to
helical suppressor 20 must necessarily be out-of-phase with
subsequently supplied vibrations adjacent the helical suppressor
19. Since suppressor elements 19 and 20 are reversely wound, the
opposed vibrations tend to neutralize each other. Furthermore, this
neutralizing action may, if desired, be emphasized by the use of
more than a pair of suppressor elements such as 19 and 20,
additional suppressor elements 16, 17, and 18 being depicted in the
drawing. Of course, it will be understood that more than five
suppressor units may be used if desired although satisfactory
results may be achieved with only two such oppositely wound units
particularly if the number of helical windings is sufficiently
great of the order of six or eight, for example.
Any unsuppressed vibrations which pass through the aperture 31
formed axially in partition 14 are admitted to the resonant chamber
defined by partition 14 and outer configuration as indicated by the
numeral 33 about its aperture 31. Similarly, the inner surface of
end wall 32 is dished as indicated at 34 and a throat portion 35 is
formed on the inner surface of end wall 32. The throat portion 35
defines a part of the axial passageway 36 formed in end wall
32.
A sound deadening action is achieved by variations in the thickness
of the tubular outer housing 3. Furthermore, these portions of
different thicknesses are of varying lengths axially of the outer
surface of tubular housing 3. For example, thick knurled portion 37
is of less axial length than thick knurled portion 38 as best shown
for example in FIG. 3. Furthermore, thin unknurled portion 39 is of
greater length axially than thin unknurled portion 40. These random
variations have been found to be particularly effective as sound
dampening means.
A suppressor 2' in FIG. 6 is a variant from suppressor 2 of FIGS. 2
and 3. End wall element 5 is divided with external threads which
engage internal threads in the housing 3'. Partition 14' is
provided with external threads which engage internal threads in the
housing 2'. A slot 14" is provided in the partition 14' to permit
its being threaded into the housing 3' by means of a tool such as a
screw driver. A partition 9' is slidingly received in the housing
3' and is separated from the end wall 5 to define an entry chamber
4' by means of a spacer element 45. Between partition 9' and
partition 14' are retained oppositely wound helical suppressors 19'
and 20'.
Provided at the discharge end of the suppressor 2' is an assembly
46 which defines both at least the greater part of the resonance
chamber, all of which lies between partition 14' and end wall
32',and a means for eliminating the otherwise occurring "popping"
sound of a bullet exiting from the silencer.
Assembly 46 consists of apertured end wall defining elements 32'
and 50, a sleeve 51 and apertured plugs 52, 53, 54, and 55 of a
resilient material such as a polyurethane. Sleeve 51 is press fit
on end wall 50 and end wall 32' it press fit onto sleeve 51. The
assembly 46 is retained in the housing 3' by means of external
threads provided on the end wall 32' which engage internal threads
provided in the housing 3'.
The apertures in the plugs 52 and 53 are of smaller diameter than
the bullet. However, each of these plugs is provided with
diametrically opposed radial cuts which communicate with the
aperture and which together with the aperture define a diameter at
least equal to and preferably exceeding the diameter of the bullet.
These radial cuts are designated 52' and 53' relative to plugs 52
and 53, respectively. Passage of the bullet through the aperture in
the plug 52 causes the plug 52 to protrude into the aperture
through the plug 54 and the plug 54 acts as a back-up to help
prevent shearing of the plug 52. The plugs 53 and 55 likewise
cooperate together. In some instances, it may preferred to provide
that the plugs 54 and 55 be of a softer material than plugs 52 and
53.
When the plugs have worn out, the assembly 46 may simply be
unthreaded from the housing and a new assembly threaded into the
housing.
In FIG. 7 is illustrated a device which may be incorporated with a
suppressor, such as that of FIGS. 2 and 3 or FIG. 6, to permit
mounting of the suppressor on the barrel of a firearm, particularly
a pistol, by means of the sight, in the form of, for example, an
ear, conventionally provided at the muzzle end of the barrel. The
mounting device 60 is in the configuration of a tube 61 provided
with a L-shaped slot 62 and an apertured and externally threaded
extension 63. The device 60 may be mounted on the suppressor of
FIGS. 2 and 3 or that of FIG. 6 by means of the external threads on
the extension 63 engaging the internal threads in the end wall 5.
The internal diameter of the tube 61 is greater, preferably only
slightly greater, than the external diameter of the barrel of the
firearm. The longitudinal arm of the slot 62 which is parallel to
the axis of the tube 61 is of a width at least slightly greater
than the width of the sight at the muzzle of the barrel. The other
arm of the slot 62 which is at right angles to the longitudinal
arm, is of a dimension parallel to the axis of the tube 61 greater
than the length of the sight and preferably only slightly greater.
Hence, mounting of the suppressor is effected simply by sliding the
tube 60 onto the barrel with the longitudinal arm of the slot 62 in
alignment with and thereby receiving the front sight. Then, when
the front sight reaches the other arm of the slot 62, the
suppressor is rotated to position the sight in the other arm of the
slot. If it is provided that the fit between the sight and the
other arm of the slot be relatively snug, the suppressor will not
inadvertently rotate from the position from which it is locked onto
the barrel to the position in which it may be slid off the
barrel.
In FIGS. 8 and 9 are illustrated the entry and resonance chambers,
respectively, of a silencer according to the invention modified by
incorporation therein of baffles according to the invention.
In FIG. 8, the entry chamber 4" is defined between the end wall 5
having external threads engaging internal threads in the housing 3"
and the partition 9' slidingly received in the housing 3". The
spacer element 45 defines an initial portion of the chamber 4"
which initial portion does not contain baffle construction. Between
the spacer element 45 and the partition 9' are serially arranged
identical baffles 70. Each of the baffles 70 consists of arcuate
walls 71 defining an aperture 72 of continually unidirectionally
changing diameter and a cylindrical annular wall 73 joining with
the wall 71 at the wide end of the aperture 72. It will be
appreciated that the actual structure operating as a baffle is the
apertured wall 71 and that the wall 73 merely functions as a spacer
element. It will be noted that in the embodiment illustrated in
FIG. 9 the end wall 32' is provided with an internal configuration
closely similar to the configuration of the baffles 70.
Excess pressure interfering with the most effective operation of
the silencer may develop in the silencer housing particularly in
the entry chamber. With this problem in mind, a relief valve
communicating with the interior of the housing, particularly the
entry chamber, may be provided. Two examples of such relief valves
through the housing 3 are illustrated in FIGS. 10 and 11.
In FIG. 10, received in a threaded aperture in the housing 3 is an
externally threaded hollow element 80 having a chamfered internal
shoulder 81 defining a valve seat. A valve closure in the form of a
ball 81a, such as a common ball bearing, rests on the valve seat
81. The free end of an upwardly extending extension 82 of the
element 80 is provided with both internal threads and external
threads. Received on the extension 82 by means of the internal
threads is an element 83 having an externally threaded shoulder 84
and a projection 85 defining a valve stop. Around the valve stop 85
and between the shoulder 84 and the ball 81a is retained a spring
86. A predetermined pressure such as 200 p.s.i., on the side of the
ball facing inwardly of the housing 3 is required to compress the
spring 86 thereby to lift the ball 81a from the seat 81. The valve
stop 85 prevents over-compression of the spring 86. Gas thereby
released from with the housing 3 escapes through radial ports 87
provided in the extension 82 and radial ports 88 provided in a cap
89 mounted on the extension 82 by means of internal threads
engaging the external threads of the extension 82.
Another valve construction is illustrated in FIG. 11. This valve
construction has no moving parts and provides a continual bleed off
to prevent excessive pressure build up. This valve consists of a
nipple 90 having an externally threaded portion 91 which portion
engages internal threads through the housing 3. Portion 92 of the
nipple 91 is in the configuration of a hexagonal nut to facilitate
insertion into or removal from the housing 3 of the nipple 90 by
means of a wrench. Extending upwardly from the portion 92 is a
portion 93 provided with external threads. An axial bore 94 in the
nipple 90 communicates with four radial apertures 95 (only one of
which is shown in FIG. 11) in the portion 93. The apertures 95 are
equidistantly spaced at 90.degree. intervals around the periphery
of the portion 93. A wall defining element 96 provided with an
axial bore slightly greater in diameter than the diameter of the
nipple portion 93 is slidingly received onto the nipple portion 93.
The element 96 is provided with six radial apertures 97 (only two
of which appear in FIG. 11) equidistantly spaced at 60.degree.
intervals about the periphery of the element 96. Element 96 is so
oriented relative to nipple 90 that the apertures 97 are not in
alignment with the apertures 95. A cap 98 is provided with an
internally threaded axial bore which threading engages the external
threading on the nipple portion 93 whereby the cap 98 is secured to
the nipple portion 93 and firmly retains the element 96 against the
upper surface of the nipple portion 92. The elements are so
dimensioned with the internal diameter of the cap 98 slightly
exceeding the diameter of the nipple portion 92 and the annular
cylindrical side wall 99 of the cap 98 not quite reaching the
housing 3 that a constricted and tortuous flow path for escaping
gas thereby is defined. The path is further tortuous insofar as the
apertures 95 and 97 are not aligned with each other. Hence, the
valve serves to relieve excess pressure; on the other hand,
excessive bleed off is prevented by means of a structure which
causes a considerable pressure drop. An advantage of this
construction is the absence of moving parts.
Not only does a silencer of this invention function effectively as
a silencer, but when used with a firearm it also functions as a
flash inhibitor so as effectively to render the flames of the
associated powder burning action invisible.
While particular embodiments of the invention have been shown and
described, the invention is not limited thereto and it is intended
in the appended claims to cover such changes and modifications as
fall within the true spirit and scope of the invention.
* * * * *