Closure fasteners – Bolts – Multiple
Reexamination Certificate
2000-10-04
2002-08-06
Luu, Teri Pham (Department: 3677)
Closure fasteners
Bolts
Multiple
C292S163000, C292S164000, C277S637000
Reexamination Certificate
active
06428057
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to door latches, and more particularly to a door latch for retaining a cap on a muzzle during static and dynamic loading.
(2) Description of the Prior Art
In firing systems for various projectiles, muzzle doors, or caps, are used to prevent intrusion of foreign objects into the muzzle prior to firing of the projectile. The design of the muzzle door latch, i.e., its attachment to the muzzle, is such that the cap can easily detach from the muzzle upon firing the projectile. The caps are further designed to fall cleanly away from the muzzle upon detachment so as to provide a clear trajectory for the projectile.
FIG. 1
shows a prior art muzzle cap
10
in cross section. It is noted that the cap assembly components are generally symmetrical about the centerline of muzzle
12
. Thus, reference numerals may be indicated for only one of such symmetrical components. Cap
10
is sized to fit within muzzle
12
with a slight clearance
14
between cap
10
and muzzle wall
12
a
. Cap
10
includes a circumferential groove
10
a
about its edge
10
b
adjacent interior muzzle wall
12
a
. Elastomeric ring seal
16
is positioned in groove
10
a
, such that cap
10
is retained within muzzle
12
by friction between seal
16
and muzzle wall
12
a
. To ensure cap
10
exits muzzle
12
cleanly upon firing a projectile from muzzle
12
, two roller guides
18
are attached to cap
10
in diametrically opposed relation by means of bolts
20
. Each guide
18
is attached to front surface
10
c
of cap
10
and extends radially past the exterior
12
b
of muzzle
12
. Pin
22
and roller
24
are attached to end
18
a
of guide
18
, such that roller
24
is in a spaced apart relation with end
18
a
. Muzzle extension plate
26
is affixed to exterior
12
b
of muzzle
12
and extends slightly beyond end
12
c
of muzzle
12
. When cap
10
, with attached guide
18
, is positioned into muzzle
12
, roller
24
is seen to fit over plate
26
, with plate
26
extending between roller
24
and end
18
a
of guide
18
. Upon firing a projectile, the action of rollers
24
against plates
26
causes cap
10
to exit past end
12
c
of muzzle
12
without rotating within muzzle
12
. This prevents jamming of cap
10
within muzzle
12
and allows cap
10
to fall cleanly away from muzzle
12
. Additionally, rollers
24
assist in aligning cap
10
with muzzle
12
during insertion of cap
10
within muzzle
12
. It can also be seen from
FIG. 1
that guides
18
allow muzzle cap
10
to be inserted into muzzle
12
only until guides
18
contact muzzle end
12
c
, thus also ensuring proper positioning of cap
10
within muzzle
12
.
However, the prior art configuration of
FIG. 1
allows muzzle cap
10
to separate from muzzle
12
during vibrational loads. Seals
16
begin to wear with repeated insertion and detachment of cap
10
. As only frictional forces between seal
16
and muzzle
12
hold cap
10
in place, wearing of seal
16
can cause cap
10
to loosen within muzzle
12
. Shearing pins may be added between the cap and the muzzle such that the cap detaches at a predetermined load. However, installation of shearing pins requires additional operator training and involvement. Manual locking and unlocking of the cap to the muzzle would suffice to keep the cap within the muzzle. Such a design would require visual verification of the lock condition prior to a firing exercise. Further, each of these designs require the use of separate, small parts that may be misplaced or damaged during firing.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide muzzle door latch that provides additional resistance to vibration.
Another object of the present invention is to provide a vibration resistant muzzle door latch that does not require retraining of personnel for installation.
Still another object of the present invention is to provide a muzzle door latch that is integral with current muzzle caps.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a muzzle door latch, or attachment mechanism, incorporates spring-loaded plungers acting within concave surfaces to provide additional resistance to vibration. The door, or cap, has an elastomeric seal about its outer circumference, which fits snugly within the muzzle. Diametrically opposed guides are attached to the outer side of the cap and extend radially past the circumference of the muzzle, thus allowing the cap to be inserted into the muzzle only until the guides meet the edge of the muzzle. A plate is attached to the exterior of the muzzle, corresponding to each guide, and each plate extends slightly beyond the end of the muzzle. Each guide has a roller at its end furthest away from the cap and attached to the guide so as to have a gap between the roller and exterior of the muzzle. The axis of the roller is oriented such that the roller is orthogonal to the axis of the muzzle and tangential to its corresponding plate surface. When the cap is positioned within the muzzle, the portions of the plates extending beyond the end of the muzzle fit within the gap and the rollers engage the outer surface of the plates. The portions of the plates extending beyond the muzzle are machined to have a concave indentation on their inner surface, i.e., the surface facing towards the interior of the muzzle. Each guide has a pocket formed in its surface facing the concave indentation. The spring-loaded plunger fits within the pocket and is biased in a direction against the concave surface. As the cap is being placed within the end of the muzzle, the plungers are depressed against the spring within the pocket while clearing the end of the plate. Once the cap is fully seated into the muzzle, i.e., when the guides contact the outer edge of the muzzle, the springs force the plungers into the concave indentation on the plate. Thus, even if the frictional force between the seal and the muzzle is diminished by wear, the plungers serve to hold the muzzle door, or cap, in place. As the cap installs in the same manner as prior art caps, personnel need not be retrained to install the cap. Further, the spring-loaded plunger is an integral part of the cap so there are no additional, or small parts that can be misplaced.
REFERENCES:
patent: 884481 (1908-04-01), Glaus
patent: 1194636 (1916-08-01), Joy
patent: 2494956 (1950-01-01), Mendelsohn
patent: 6336641 (2002-01-01), Williams
Kasischke James M.
Lall Prithvi C.
Luu Teri Pham
McGowan Michael J.
The United States of America as represented by the Secretary of
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