Actuating Mechanism

Abstract

An actuating mechanism in which a source of fluid is directed against an end wall of a rigid body portion having an open cavity formed therein to create pressure waves of fluid which pass through the length of the cavity to the closed end thereof to cause a temperature rise at the closed end. This temperature rise is utilized to ignite an explosive device which, in turn, is utilized to accomplish work.

Description

BACKGROUND OF THE INVENTION

The invention herein described was made in the course of or under a contract or subcontract thereunder, with the Department of the Army.

This invention relates to an actuating mechanism and, more particularly, to such a mechanism utilizing a fluidic device to produce thermal energy.

Many existing actuating mechanisms employ electrical devices, such as spark gaps or resistance wires, which require electrical inputs. For example, the igniter for an oil burner in a home heating system uses a high-voltage spark gap. Also, on many aerospace and ordinance systems it is desirable to initiate operations from a remote location, in which case pyrotechnic devices are used and the igniter thereof is energized by a hot resistance wire. Further, explosive-actuated valves, as well as solid grain hot gas generators, normally utilize an electrical initiated squib or exploding bridge to trigger the explosive charge. However, due to the low-power consumption of the electrical igniter in these devices, false triggering can be induced by lightning, static electricity, radiofrequency interference, nuclear radiation, etc.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an actuating mechanism which is free from electrical components and connections, and which therefore eliminates the above disadvantages associated with an electrical actuating mechanism.

Toward the fulfillment of this object, the actuating mechanism of the present invention comprises a rigid body portion having a cavity formed therein, said cavity having an open end and a closed end, means to direct a source of fluid against an end wall of said body portion and toward said open end to create pressure waves of fluid which pass through the length of said cavity to said closed end to cause a temperature rise at said closed end, and means responsive to said temperature rise for accomplishing work.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings for a better understanding of the nature and objects of the present invention. The drawings illustrate the best mode presently contemplated for carrying out the objects of the invention and are not to be construed as restrictions or limitations on its scope. In the drawings:

FIG. 1 is a cross-sectional view depicting the actuating mechanism of the present invention used in conjunction with a valve; and

FIG. 2 is a view similar to FIG. 1 but showing the actuating mechanism of the present invention used in conjunction with a hot gas generator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring specifically to the embodiment of FIG. 1, the reference numeral 10 refers to a housing in which a nozzle 12 is formed having an internally threaded entrance 14 adapted to accommodate a corresponding externally threaded tube or the like (not shown) for the introduction of pressurized fluid, such as gas, into the nozzle in the direction indicated by the arrow. The exit end of the nozzle 12 converges as shown, and communicates with an opening 16 formed in the housing 10.

A tubular resonance cavity 18 is formed in a rigid body portion 19 of the housing 10, and the entrance to the cavity 18 communicates with the opening 16. The other end of the cavity 18 is closed by a pyrotechnic explosive 20, in the form of a lead azide, or other similar material, which is adapted to ignite upon the latter end portion of the cavity 18 reaching a certain temperature, as will be explained in detail later.

An additional housing 21 is provided which has one end threadably engaging end of the housing 10, and two chambers 22 and 24 formed therein. A piston 26 is reciprocally mounted in the chamber 22 with the stem of the piston slideably extending through a partition 28 formed through the housing 21 and into the chamber 24. A guillotine 30 is formed on the other end of the stem in the chamber 24 and is disposed in proximity to a diaphragm 32 extending across the chamber 24 and adapted to prevent flow of an additional fluid through the chamber 24 from an inlet port 34 to an outlet port 36.

In operation, pressurized fluid, such as gas, is introduced into the nozzle 12 and flows outwardly therefrom into the opening 16 in the direction indicated by the arrows, whereby a small portion enters the cavity 18 and the remaining portion impinges upon the front wall of the body portion 19 and exits from the system in a direction at right angles to the direction of flow into the cavity 18. After a very short time the cavity fills up and the entire flow impinges off of the wall and exits from the housing. In this manner an unstable wave will be formed at the entrance to the cavity 18, which wave oscillates back and forth and causes small pressure waves to travel the length of the cavity 18 and compress the gas trapped at the closed end thereof, thus adding energy to the gas at every cycle of oscillation. Accumulation of this energy input per cycle causes the temperature at the closed end of the cavity 18 to rise appreciably to a point whereby it ignites the explosive 20.

The thermal energy thus created drives the piston 26 in a direction from left to right as viewed in FIG. 1, and causes the guillotine 30 to sever the diaphragm 32 and thus permit flow of the additional fluid from the inlet port 34 through the chamber 24 and out the outlet port 36.

It is thus seen that an effective valve is formed in the chamber 24 which is actuated by gas flow into the nozzle 12, while all electrical components and connections are eliminated.

In the embodiment of FIG. 2, a housing is provided which is identical to the housing 10 of the embodiment of FIG. 1 and therefore will not be described in detail. As in the previous embodiment, a pyrotechnic explosive 20 closes the exit end of the cavity 18 formed in the housing 10.

According to this embodiment, an additional housing 40 is threadably engaged to an end of the housing 10, and houses a solid grain propellant 42 which may be in the form of an ammonium perchlorate. The propellant 42 is cast in the form of a tube having a hollow portion 44 and is adapted to be ignited by the thermal energy created by the explosive charge 20, to produce a hot gas. In this manner, upon the temperature at the closed end of the cavity 18 reaching a temperature sufficient to ignite the explosive charge 20, the thermal energy created ignites the solid grain propellant 42, and generates the hot gas which passes from the housing 40 through an outlet port 46. The presence of the hollow portion 44 in the propellant 42 aids in the distribution of the thermal energy to the propellant 42 and in the flowing of the hot gas to the outlet port 46. The hot gas thus created may be used for many applications, such as to ignite a rocket engine, etc.

It is noted that, in each embodiment, the flow from the nozzle 12 can be supersonic, in which case the wave created at the entrance to the cavity 18 will be a shock wave.

It is thus seen that, by use of the actuating mechanism of the present invention, electrical inductions and other cross-coupling inputs from an adverse environment are eliminated, as well as the cost and vulnerability of spark gaps to outside weather environments. Also, since high-pressured air is normally readily available, the mechanism is relatively inexpensive in operation.

It can be appreciated that several variations in the above embodiments are possible without departing from the scope of the invention. For example, although the cavity 18 has been shown with a cylindrical cross section, it is understood that it can take other configurations such as rectangular, conical, etc. Also, various alternate configurations of the nozzle 12 may be employed such as a convergent-divergent type, and various stagings of the flow of the gas can be utilized.

Of course, other variations of the specific construction and arrangement of the mechanism disclosed above can be made by those skilled in the art without departing from the invention as defined in the appended claims.

Claims

I claim:

1. An actuating mechanism comprising a first rigid body portion having a longitudinal axis having a cavity formed therein coaxially therewith, said cavity having an open end and a closed end, means to direct a source of fluid against a wall of said first body portion and towards said open end to create pressure waves of fluid which pass through the length of said cavity to said closed end to cause a temperature rise at said closed end, and means responsive to said temperature rise for accomplishing work, wherein said means to direct a source of fluid against the wall of said first rigid body portion includes a second rigid body portion fixedly connected to said first rigid body portion, said second rigid body portion having a longitudinal passage connected to said cavity coaxially therewith, said second rigid body portion having a transverse passage connected to said longitudinal passage and to said cavity and extending transverse to said longitudinal passage, said second rigid body portion having a radially outer surface, said longitudinal passage having a converging end portion having an outlet opening, said outlet opening facing said cavity open end coaxially therewith, said transverse passage having a radially inner inlet end disposed adjacent said cavity open end and having a radially outer outlet end having a vent opening extending through said exterior surface.

2. The mechanism of claim 1 wherein said means for accomplishing work comprising an explosive charge in heat exchange relation with said closed end, said temperature rise causing said explosive charge to ignite, and wherein said actuating mechanism is a one-piece rigid housing arranged so that said first rigid body portion and said second rigid body portion are axially spaced portions thereof, and wherein said transverse passage is disposed substantially at right angles to said longitudinal passage, and wherein said first body portion has an axially outer end face having a recess receiving said explosive charge forming said cavity closed end.