Ammunition and explosives – Mines – Marine type
Reexamination Certificate
1998-09-18
2001-03-20
Jordan, Charles T. (Department: 3641)
Ammunition and explosives
Mines
Marine type
C102S416000, C102S229000, C102S200000
Reexamination Certificate
active
06202559
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to actuators that operate when submersed in a fluid environment, and more particularly to an air-safed mechanical actuator that operates in deep or shallow water (and/or cold water environments) only when the actuator is properly readied for operation and submersed in the fluid environment.
BACKGROUND OF THE INVENTION
Ordnance such as grenades, bombs, mines and torpedoes typically have an actuator in the form of a fuze or detonator which permits initiation of a main charge only when certain conditions are met. For example, if the ordnance is only supposed to detonate underwater, the fuze is designed to prevent in-air detonation. Several such fuzes are known in the prior art.
U.S. Pat. Nos. 3,765,331 (the '331 patent) and 3,765,332 (the '332 patent) disclose water-armed air-safetied detonators in which a plurality of small explosives are aligned in a spaced-apart fashion in a fuze housing. The first of these small explosives is a delay charge which ignites when the ordnance is launched or released. The delay charge eventually burns and flashes down an adjacent housing bore to ignite a transfer charge. Detonation of the transfer charge releases energy that is either used to move a piston (the '331 patent) or is in the form of a shock wave (the '332 patent). This released energy is delivered to a chamber that is flooded with either air or water depending on the environment in which the fuze is immersed. Adjacent the flooded chamber is a firing pin/percussion primer (the '331 patent) or just a percussion primer (the '332 patent). If the flooded chamber is filled with air, the released energy in the form of a moving piston (the '331 patent) or shock wave (the '332 patent) will not transfer through to the next stage of the fuze. If, however, the fuze is submerged in water, the flooded chamber is filled with water and the released energy entering the flooded chamber is transferred therethrough to the next stage of the fuze.
Although being air-safed, these devices still have several disadvantages. The use of explosives as part of the fuze train can be inherently problematic. These problems range from the safety concerns related to the construction and storage of such devices to the fact that these fuzes are not reusable. In general, use of stored energy for arming and firing is considered bad design practice because the energy is available at all times during storage and transportation, and may therefore be released due to unforeseen causes or situations. Further, the use of explosives eliminates these devices from consideration as an all-purpose actuator that is water-armed and air-safed.
To overcome the problems inherent with the use of explosives, a mechanical underwater firing mechanism is disclosed in U.S. Pat. No. 2,660,952. Briefly, a spring-loaded plunger is mounted in a housing. The head of the plunger is formed with a recess. Fitted in the housing coaxial with the plunger is a plug having a central bored portion in which a firing pin is temporarily positioned intermediately therein by a shear pin. As a result, small chambers are defined in the central bored portion on either side of the firing pin. The central bored portion of the plug opposes the plunger's recess and is sized at its exterior to fit within the recess. When the spring-loaded plunger is cocked, the head of the plunger is spaced apart from the central bored portion of the plug to define a chamber within the housing. An opening in the side of the housing at the chamber allows the environment surrounding the housing (e.g., air or water) to fill the chamber.
When the spring-loaded plunger is released, the plunger recess envelops the central bored portion of the plug to compress any fluid trapped in the small chamber of the central bored portion between the firing pin and the head of the plunger. If the trapped fluid is air, the compression thereof will not develop forces sufficient to cause the firing pin's shear pin to fail. However, if the trapped fluid is water, the compression forces imparted by the plunger will be sufficient to cause failure of the firing pin's shear pin thereby allowing movement of the firing pin to impact a primer.
While eliminating the use of explosives in the firing mechanism, this device has other disadvantages. For example, the requirement that a small chamber be defined in the central bored portion opposing the head of the plunger raises the possibility that an air bubble will form therein when the device is submerged in water. The presence of such an air bubble could prevent the mechanism from functioning underwater. At the same time, the requirement that the small chamber be present in the central bored portion could also bring about an unwanted firing. This could occur if the mechanism were not cocked and inadvertently dropped in water. Water could seep into the mechanism and fill the small chamber. Then, an in-air release of the (cocked) plunger could bring about movement of the firing pin just as if the mechanism were submerged in water. This is because surface tension in the small chamber could cause enough water to be retained therein to bring about this undesirable situation. Another disadvantage brought about by the requirement of the small chamber arises in sub-freezing environments. Specifically, water in the small chamber could quickly freeze due to its small volume. If this occurs, the mechanism will not function.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a mechanical actuator that is air-safed.
Another object of the present invention is to provide an air-safed mechanical actuator that can be used to bring about actuating movement only when submerged in an incompressible fluid.
Still another object of the present invention is to provide an air-safed mechanical actuator that operates reliably even in sub-freezing temperatures.
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 mechanical device for generating actuating movement has a housing defining a first bore and a second bore contiguous with one another. The second bore can have a smaller diameter than the first bore. The housing also defines at least one radial port allowing an environment about the housing to communicate with the first bore. A first piston is slidably mounted in the first bore. A second piston is slidably mounted in the second bore and is positioned so that it is flush with the first bore. A spring, coupled to the first piston, is capable of an at-rest state in which the first piston is positioned in the first bore to seal off the radial port(s) while being spaced apart from the second piston. The spring is also capable of a compressed state in which the first piston is positioned such that the radial port(s) communicate with the first bore between the first piston and the second piston. When the housing is submerged in an incompressible fluid and the spring is in its compressed state, the radial port(s) admit fluid into the first bore. Then, when the spring is released from its compressed state and allowed to transition to its at-rest state, the first piston moves to seal off the radial port(s) and subsequently pressurize the fluid in the first bore between the first piston and the second piston. The pressurized fluid drives the second piston along the second bore to create the actuating movement.
REFERENCES:
patent: 2660952 (1953-12-01), Mohaupt
patent: 3765331 (1973-10-01), Montesi
patent: 3765332 (1973-10-01), Baker et al.
patent: 4100855 (1978-07-01), O'Callaghan
Lewis Keith B.
Sanford Matthew J.
Bechtel, Esq. James B.
Bergen, Esq. Peter J. Van
Jordan Charles T.
The United States of America as represented by the Secretary of
Thomson M.
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