U.S. patent number 3,714,726 [Application Number 05/092,559] was granted by the patent office on 1973-02-06 for recoil stock.
Invention is credited to Paul E. Braun.
United States Patent |
3,714,726 |
Braun |
February 6, 1973 |
RECOIL STOCK
Abstract
A rubber membrane is sealed between a pair of front and back
plates forming a fluid filled chamber secured to the butt end of a
gun stock. The shock caused by the firing of the gun is translated
to the fluid chamber causing the rubber membrane to expand radially
with respect to the gun axis resulting in relative movement of the
front and back plates toward each other to absorb and relieve the
user of the shock impact. A pair of spring loaded pistons
longitudinally positioned between the front and back plates provide
proper realignment of the recoil pad after firing. A U-shaped
spring clamp prestresses the fluid chamber to provide immediate
shock absorbing expansion of the membrane when the gun is
fired.
Inventors: |
Braun; Paul E. (Miami, FL) |
Family
ID: |
22233833 |
Appl.
No.: |
05/092,559 |
Filed: |
November 25, 1970 |
Current U.S.
Class: |
42/74 |
Current CPC
Class: |
F41C
23/06 (20130101) |
Current International
Class: |
F41C
23/06 (20060101); F41C 23/00 (20060101); F41c
023/00 () |
Field of
Search: |
;42/74 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Jordan; C.T.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows.
1. A shock absorbing recoil device adapted to be secured to the
butt end of a gun comprising, in combination, a chamber means
filled with a generally incompressible fluid, said chamber means
having front and rear spaced end wall portions and an annular side
wall, said front and rear wall portions having a normal spacing
therebetween except when said gun is fired, at least said side wall
being comprised of a resilient and flexible membrane so that when
said gun is fired, the recoil shock is absorbed by the radial
expansion of said membrane with said normal spacing between said
front and rear wall portions being reduced.
2. A shock absorbing recoil device adapted to be secured to the
butt end of a gun comprising, in combination, a fluid filled
chamber means, said chamber having a first and second plate means
spaced axially with respect to the gun axis, said plate means
forming the ends of said chamber, and a flexible membrane secured
to the periphery of said plate means, said membrane forming the
sides of said chamber, one of said first and second plate means
movable axially with respect to the other between a set position
wherein said recoil device is ready in preparation for said gun to
be fired and a recoil position wherein said second plate means is
in closer proximity to said first plate means and said flexible
membrane has expanded radially with respect to said gun axis due to
the displacement of the fluid, said membrane expansion absorbing
the shock resulting from the firing of said gun causing the fluid
to displace.
3. The combination according to claim 2 wherein said fluid is
comprised of an incompressible liquid, and said flexible membrane
is comprised of a resilient rubber.
4. The combination according to claim 2 wherein said combination is
further characterized as including a realignment means cooperating
with said first and second plate means urging said plate means into
said set position.
5. The combination according to claim 4 wherein said alignment
means is comprised of a spring loaded piston-cylinder mounted
between said first and second plate means, said alignment means
providing a damper for said chamber movement when said gun is
fired, and further biasing said plate means into their set position
after said gun is fired.
6. The combination according to claim 5 wherein said combination is
detachably mounted to said gun stock to permit removal therefrom,
said combination further including a boot surrounding said chamber
and adaptable to fit various sized gun stocks, said boot being in
part spaced from said membrane to permit the expansion of said
membrane to absorb said gun shock.
7. The combination according to claim 2 wherein means are provided
for prestressing said chamber to reduce any lag time resulting in
said chamber compression and expansion when said gun is fired.
8. The combination according to claim 7 wherein said prestress
means is comprised of a U-shaped clip spring disposed around a
portion of said membrane, said U-shaped clip exerting a compressive
force on said membrane to prestress it.
9. The combination according to claim 1 wherein said combination is
further characterized as including an alignment means cooperating
with said first and second wall portions to urge said wall portions
into said normal spacing.
10. The combination according to claim 9 wherein said alignment
means is comprised of a spring loaded piston-cylinder mounted
between said first and second wall portions, said alignment means
providing a damper for said chamber movement when said gun is
fired, and further biasing said wall portions into their normal
spacing after said gun is fired.
11. The combination according to claim 1 wherein means are provided
for prestressing said chamber to reduce any lag time resulting in
said chamber compression and expansion when said gun is fired.
Description
BACKGROUND OF INVENTION
This invention relates to a novel recoil device particularly
adapted for use with a gun stock.
The advent of lighter fire arms has intensified the need for an
efficient mechanical shock absorber which is both practical and
economically feasible. The prior art suggests various devices which
force the hydraulic fluid through a restricted passageway or
orifice to absorb the shock. These proposals have proven to be
complex in their structure and expensive as well as difficult to
assemble. In addition, they have proven inadequate in properly
realigning or repositioning the absorbing mechanism after firing.
Failure to do so adversely affects the accuracy of the gun.
In addition, a common drawback to existing proposals has been the
fact that they are built completely into the gun stock and hence
not easily adaptable to older existing firearms. Also, where a
replacement is required, the entire stock must then be
replaced.
SUMMARY OF INVENTION
The recoil device provided by this invention is comprised of a
fluid filled chamber having plate means and expansion means so that
when the gun is fired, the shock acting on the chamber causes the
expansion means to expand radially with respect to the barrel axis
permitting the end plate means to move axially toward each other to
provide relief to the shoulder of a person firing the gun. In
addition, novel means are provided for resetting and realigning the
end plate means and chamber after the weapon is fired so that it
can be accurately fired again.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary view in elevation of the recoil device
provided by this invention;
FIG. 2 is a cross-sectional view taken along line 2--2 of FIG.
1;
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1;
and
FIG. 4 is an enlarged cross-sectional view of the encircled portion
shown in FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in detail, FIG. 1 shows the recoil
pad 10 proposed by this invention mounted to the butt end of a gun
stock 12. The pad is mounted to the stock by a pair of screws 14
which fit radially with respect to the gun axis through
counterholes 16. A frontal plate 20 having a pair of axially
extending brackets 18 are threadably engaged by screws 14 to join
the pad to the stock. The screw head 15 seats on the bottom surface
17 of the counterholes to draw the bracket up tight against the
stock. The butt end of stock 12 is cut out to permit insertion of
brackets 18 to provide positive mounting of the pad to the
stock.
A fluid filled chamber 22 is defined by a pair of front plates 24,
26 and a pair of end plates 28, 30. The plates form the respective
ends of the chamber while the sides are comprised of a flexible
membrane 32 which is joined along the periphery of the plates as
follows. The plates are generally oval in shape (FIG. 2) to conform
to the lateral cross section of the gun stock and recoil pad. Each
plate includes a continuous groove 34 along the peripheral edge so
that when frontal plates 24, 26 and end plates 28, 30 are
positioned in facial abutment, grooves 34 form an O-ring groove 36
as shown in FIG. 4. A pair of O-rings 38, 38 are integrally formed
with the membrane and depend from the interior surface of the
membrane along its edges. O-rings 38, 38 are compressed into groove
36 when the end and frontal plates are joined together to provide a
fluid tight seal between the plate and membrane. The compression
fit is provided by a plurality of threaded set screws 40 which join
the pair of front and end plates together as shown in FIG. 1.
Preferably, the chamber is filled with an incompressible liquid
such as an hydraulic fluid to provide recoil or shock absorbing
relief as follows. When the gun is fired, the recoil shock from the
gun travels down the stock or gun axis toward the shooter's
shoulder, causing the stock to move abruptly rearward. As the stock
moves backward, the shock or compression force is translated to the
liquid in the chamber, but since the preferred fluid is
incompressible, an equal pressure is exerted in all directions
through the fluid. As a result of the resilient and expandible
characteristics of the membrane, and the inflexibility of the end
and front plates, the pressure exerted through the fluid causes the
membrane to expand radially or outwardly with respect to the gun
axis. This expansion permits joint movement of the front and end
plates toward each other thereby providing shock absorption relief
for the shooter's shoulder. Preferably, the membrane is comprised
of rubber which has been found to provide excellent resilient
characteristics.
Preferably, the chamber and membrane are covered with a decorative
rubber hood 42 which is flexible to fit over various sized stocks
when the device is installed in different sized stocks.
Additionally, if the hood is too large, portions can be trimmed
from the sides or inner end of the hood to conform to the
particular size of the stock. A spacing 44 between the hood and
membrane is provided around the membrane so that when the gun is
fired and the membrane expands, there is sufficient room for it to
expand.
It has been found that in the use of a flexible membrane such as
that described above, it is advantageous in order to provide a
linear type shock absorbing movement of the pad with respect to
time that the chamber be slightly prestressed. That is, if the
chamber is not sufficiently prestressed, upon the firing of the
gun, there is a tendency for the pad to slightly mushroom prior to
full shock absorbing exertion on the pad. This provides an uneven
relief for the shooter and can affect the accuracy in firing the
gun. Thus, in order to provide positive response of the absorbing
chamber at the inception of the shock, the chamber is preferably
prestressed slightly by a U-shaped clip spring 46 which exerts a
slight inward or compression setting force on the membrane thereby
slightly prestressing the membrane. This prestressing of the
membrane eliminates the possibility of any lag time resulting from
being unable to completely fill the chamber with the hydraulic
fluid. As a result, a rapid and yet smooth continuous shock
absorption is provided.
After firing, the resiliency of the rubber membrane will bias the
plates back into a normal or preset alignment in preparation for
the next firing. However, the accuracy of the gun is in part
dependent on the proper realignment of the plates and this
alignment cannot be completely assured by the resiliency of the
membrane alone in light of the normal shock magnitude. Thus, a
means is preferably provided for positively resetting the plates
into accurate alignment.
The realignment means is provided by a pair of spring biased
pistons 50, only one of which is shown in detail in the drawings.
The pistons are spaced laterally and mounted through the front
plates 20, 24 and 26 to project into the gun stock. Describing the
upper piston mechanism in detail (shown in FIGS. 1 and 3), piston
50 is comprised of two portions, a main shaft 51 which is anchored
in end plates 28 and 30 by threaded engagement therewith and a
necked down or reduced cross section portion 70 which forms a
piston chamber 52 and extends through the piston body 54 into the
gun stock. The piston or chamber body 54 is comprised of a
cylindrical means extending into a counterbore 56 in the stock with
the front end of the cylinder in abutment with the bottom surface
58 of the counterbore. Counterbore 56 has an additional reduced
cross-sectional portion 72 which extends further into the stock and
is provided to receive portion 70 of the piston shaft.
Piston cylinder 54 is secured within the counterbore by a spring 74
mounted between end plates 28, 30 and the cylinder itself, spring
74 encircling the main shaft portion 51 of the piston. Spring 74
thus biases the cylinder into a fixed position relative to the gun
stock. Piston 50 slides relative to cylinder 54 and the gun stock
and is sealed to prevent any hydraulic fluid from entering into
chamber 52 by an O-ring 76 mounted in an O-ring groove 78 provided
on the main shaft portion 51 of the piston. This prevents any fluid
from entering chamber 52 and hence a seal is not required where the
necked down portion 70 of the piston passes through piston cylinder
54 into the gun stock.
Cylinder 54 is sealed with respect to the frontal plates in a
fashion similar to the connection of membrane 32 to the front and
end plates. An annular groove 60 is provided on the outer periphery
of cylinder 54 for receipt of an annular rubber sealing ring 62
which has an O-ring type projection 64. Projection 64 is compressed
into sealing engagement between front plates 24 and 26 which plates
include a continuous groove 66 and 69, respectively, to form an
O-ring groove 68 when the plates are in facial abutment. Again, the
O-ring projection 64 is preferably integral with the sealing ring
62. The reason for the axial width of sealing ring 62 is to provide
sufficient give between the piston 50 and cylinder 54 so that when
the gun is butted up against the shooter's shoulder, the piston and
cylinder do not become cocked out of alignment. Each shooter varies
considerably as to how and how hard he grips the gun. Therefore,
ring 62 compensates for this so that the operation of piston 50 is
smooth and hence accurate.
Thus, as the gun is fired, and the liquid filled chamber provides
shock absorption, piston 50 moves axially forward with respect to
front plates 24, 26 and stock 12 in unison with end plates 28 and
30. At the same time sprig 74 is compressed between end plate 28
and the piston cylinder to provide the proper bias required for
accurate realignment after firing. In addition to the piston and
spring arrangement providing the proper amount of resilient urging
necessary to realign the pad after firing, they also act as a
damper during firing to damp the movement of the shock absorption
liquid filled chamber in respective boot 32. This facilitates a
smooth operation of the recoil pad and prevents excessive
oscillation which could affect the accuracy of the gun. It also
provides for a rigid pad so that it can be firmly seated on the
shoulder of the user.
The recoil pad provided by this invention is extremely simple to
adapt to any existing gun stock. Of equal importance, the entire
mechanism is extremely straight forward in operation and therefore
not subject to jamming or cocking when it is realigned after
firing.
Although but one embodiment has been shown and described in detail,
it will be obvious to those having ordinary skill in this art that
the details of construction of this particular embodiment may be
modified in a great many ways without departing from the unique
concepts presented. It is therefore intended that the invention is
limited only by the scope of the appended claims rather than by
particular details of construction shown, except as specifically
stated in the claims.
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